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/* pngvalid.c - validate libpng by constructing then reading png files.
* * Last changed in libpng 1.5.2 [March 31, 2011] * Copyright (c) 2011 Glenn Randers-Pehrson * Written by John Cunningham Bowler * * This code is released under the libpng license. * For conditions of distribution and use, see the disclaimer * and license in png.h * * NOTES: * This is a C program that is intended to be linked against libpng. It * generates bitmaps internally, stores them as PNG files (using the * sequential write code) then reads them back (using the sequential * read code) and validates that the result has the correct data. * * The program can be modified and extended to test the correctness of * transformations performed by libpng. */
#include "png.h"
#if PNG_LIBPNG_VER < 10500
/* This delibarately lacks the PNG_CONST. */typedef png_byte *png_const_bytep;
/* This is copied from 1.5.1 png.h: */#define PNG_INTERLACE_ADAM7_PASSES 7
#define PNG_PASS_START_ROW(pass) (((1U&~(pass))<<(3-((pass)>>1)))&7)
#define PNG_PASS_START_COL(pass) (((1U& (pass))<<(3-(((pass)+1)>>1)))&7)
#define PNG_PASS_ROW_SHIFT(pass) ((pass)>2?(8-(pass))>>1:3)
#define PNG_PASS_COL_SHIFT(pass) ((pass)>1?(7-(pass))>>1:3)
#define PNG_PASS_ROWS(height, pass) (((height)+(((1<<PNG_PASS_ROW_SHIFT(pass))\
-1)-PNG_PASS_START_ROW(pass)))>>PNG_PASS_ROW_SHIFT(pass))#define PNG_PASS_COLS(width, pass) (((width)+(((1<<PNG_PASS_COL_SHIFT(pass))\
-1)-PNG_PASS_START_COL(pass)))>>PNG_PASS_COL_SHIFT(pass))#define PNG_ROW_FROM_PASS_ROW(yIn, pass) \
(((yIn)<<PNG_PASS_ROW_SHIFT(pass))+PNG_PASS_START_ROW(pass))#define PNG_COL_FROM_PASS_COL(xIn, pass) \
(((xIn)<<PNG_PASS_COL_SHIFT(pass))+PNG_PASS_START_COL(pass))#define PNG_PASS_MASK(pass,off) ( \
((0x110145AFU>>(((7-(off))-(pass))<<2)) & 0xFU) | \ ((0x01145AF0U>>(((7-(off))-(pass))<<2)) & 0xF0U))#define PNG_ROW_IN_INTERLACE_PASS(y, pass) \
((PNG_PASS_MASK(pass,0) >> ((y)&7)) & 1)#define PNG_COL_IN_INTERLACE_PASS(x, pass) \
((PNG_PASS_MASK(pass,1) >> ((x)&7)) & 1)
/* These are needed too for the defualt build: */#define PNG_WRITE_16BIT_SUPPORTED
#define PNG_READ_16BIT_SUPPORTED
#endif
#include "zlib.h" /* For crc32 */
#include <float.h> /* For floating point constants */
#include <stdlib.h> /* For malloc */
#include <string.h> /* For memcpy, memset */
#include <math.h> /* For floor */
/* Unused formal parameter errors are removed using the following macro which is
* expected to have no bad effects on performance. */#ifndef UNUSED
# if defined(__GNUC__) || defined(_MSC_VER)
# define UNUSED(param) (void)param;
# else
# define UNUSED(param)
# endif
#endif
/***************************** EXCEPTION HANDLING *****************************/#include "contrib/visupng/cexcept.h"
struct png_store;define_exception_type(struct png_store*);
/* The following are macros to reduce typing everywhere where the well known
* name 'the_exception_context' must be defined. */#define anon_context(ps) struct exception_context *the_exception_context = \
&(ps)->exception_context#define context(ps,fault) anon_context(ps); png_store *fault
/******************************* UTILITIES ************************************//* Error handling is particularly problematic in production code - error
* handlers often themselves have bugs which lead to programs that detect * minor errors crashing. The following functions deal with one very * common class of errors in error handlers - attempting to format error or * warning messages into buffers that are too small. */static size_t safecat(char *buffer, size_t bufsize, size_t pos, PNG_CONST char *cat){ while (pos < bufsize && cat != NULL && *cat != 0) buffer[pos++] = *cat++;
if (pos >= bufsize) pos = bufsize-1;
buffer[pos] = 0; return pos;}
static size_t safecatn(char *buffer, size_t bufsize, size_t pos, int n){ char number[64]; sprintf(number, "%d", n); return safecat(buffer, bufsize, pos, number);}
static size_t safecatd(char *buffer, size_t bufsize, size_t pos, double d, int precision){ char number[64]; sprintf(number, "%.*f", precision, d); return safecat(buffer, bufsize, pos, number);}
static PNG_CONST char invalid[] = "invalid";static PNG_CONST char sep[] = ": ";
/* NOTE: this is indexed by ln2(bit_depth)! */static PNG_CONST char *bit_depths[8] ={ "1", "2", "4", "8", "16", invalid, invalid, invalid};
static PNG_CONST char *colour_types[8] ={ "greyscale", invalid, "truecolour", "indexed-colour", "greyscale with alpha", invalid, "truecolour with alpha", invalid};
/* To get log-bit-depth from bit depth, returns 0 to 7 (7 on error). */static unsigned intlog2depth(png_byte bit_depth){ switch (bit_depth) { case 1: return 0;
case 2: return 1;
case 4: return 2;
case 8: return 3;
case 16: return 4;
default: return 7; }}
/* A numeric ID based on PNG file characteristics. The 'do_interlace' field
* simply records whether pngvalid did the interlace itself or whether it * was done by libpng. Width and height must be less than 256. */#define FILEID(col, depth, interlace, width, height, do_interlace) \
((png_uint_32)((col) + ((depth)<<3) + ((interlace)<<8) + \ (((do_interlace)!=0)<<15) + ((width)<<16) + ((height)<<24)))
#define COL_FROM_ID(id) ((png_byte)((id)& 0x7U))
#define DEPTH_FROM_ID(id) ((png_byte)(((id) >> 3) & 0x1fU))
#define INTERLACE_FROM_ID(id) ((int)(((id) >> 8) & 0x3))
#define DO_INTERLACE_FROM_ID(id) ((int)(((id)>>15) & 1))
#define WIDTH_FROM_ID(id) (((id)>>16) & 0xff)
#define HEIGHT_FROM_ID(id) (((id)>>24) & 0xff)
/* Utility to construct a standard name for a standard image. */static size_tstandard_name(char *buffer, size_t bufsize, size_t pos, png_byte colour_type, int log_bit_depth, int interlace_type, png_uint_32 w, png_uint_32 h, int do_interlace){ pos = safecat(buffer, bufsize, pos, colour_types[colour_type]); pos = safecat(buffer, bufsize, pos, " "); pos = safecat(buffer, bufsize, pos, bit_depths[log_bit_depth]); pos = safecat(buffer, bufsize, pos, " bit ");
if (interlace_type != PNG_INTERLACE_NONE) pos = safecat(buffer, bufsize, pos, "interlaced"); if (do_interlace) pos = safecat(buffer, bufsize, pos, "(pngvalid)"); else pos = safecat(buffer, bufsize, pos, "(libpng)"); if (w > 0 || h > 0) { pos = safecat(buffer, bufsize, pos, " "); pos = safecatn(buffer, bufsize, pos, w); pos = safecat(buffer, bufsize, pos, "x"); pos = safecatn(buffer, bufsize, pos, h); }
return pos;}
static size_tstandard_name_from_id(char *buffer, size_t bufsize, size_t pos, png_uint_32 id){ return standard_name(buffer, bufsize, pos, COL_FROM_ID(id), log2depth(DEPTH_FROM_ID(id)), INTERLACE_FROM_ID(id), WIDTH_FROM_ID(id), HEIGHT_FROM_ID(id), DO_INTERLACE_FROM_ID(id));}
/* Convenience API and defines to list valid formats. Note that 16 bit read and
* write support is required to do 16 bit read tests (we must be able to make a * 16 bit image to test!) */#ifdef PNG_WRITE_16BIT_SUPPORTED
# define WRITE_BDHI 4
# ifdef PNG_READ_16BIT_SUPPORTED
# define READ_BDHI 4
# define DO_16BIT
# endif
#else
# define WRITE_BDHI 3
#endif
#ifndef DO_16BIT
# define READ_BDHI 3
#endif
static intnext_format(png_bytep colour_type, png_bytep bit_depth){ if (*bit_depth == 0) { *colour_type = 0, *bit_depth = 1; return 1; }
*bit_depth = (png_byte)(*bit_depth << 1);
/* Palette images are restricted to 8 bit depth */ if (*bit_depth <= 8# ifdef DO_16BIT
|| (*colour_type != 3 && *bit_depth <= 16)# endif
) return 1;
/* Move to the next color type, or return 0 at the end. */ switch (*colour_type) { case 0: *colour_type = 2; *bit_depth = 8; return 1;
case 2: *colour_type = 3; *bit_depth = 1; return 1;
case 3: *colour_type = 4; *bit_depth = 8; return 1;
case 4: *colour_type = 6; *bit_depth = 8; return 1;
default: return 0; }}
static unsigned intsample(png_const_bytep row, png_byte colour_type, png_byte bit_depth, png_uint_32 x, unsigned int sample_index){ png_uint_32 bit_index, result;
/* Find a sample index for the desired sample: */ x *= bit_depth; bit_index = x;
if ((colour_type & 1) == 0) /* !palette */ { if (colour_type & 2) bit_index *= 3;
if (colour_type & 4) bit_index += x; /* Alpha channel */
if (colour_type & (2+4)) bit_index += sample_index * bit_depth; /* Multiple channels: select one */ }
/* Return the sample from the row as an integer. */ row += bit_index >> 3; result = *row;
if (bit_depth == 8) return result;
else if (bit_depth > 8) return (result << 8) + *++row;
/* Less than 8 bits per sample. */ bit_index &= 7; return (result >> (8-bit_index-bit_depth)) & ((1U<<bit_depth)-1);}
/* Copy a single pixel, of a given size, from one buffer to another -
* while this is basically bit addressed there is an implicit assumption * that pixels 8 or more bits in size are byte aligned and that pixels * do not otherwise cross byte boundaries. (This is, so far as I know, * universally true in bitmap computer graphics. [JCB 20101212]) * * NOTE: The to and from buffers may be the same. */static voidpixel_copy(png_bytep toBuffer, png_uint_32 toIndex, png_const_bytep fromBuffer, png_uint_32 fromIndex, unsigned int pixelSize){ /* Assume we can multiply by 'size' without overflow because we are
* just working in a single buffer. */ toIndex *= pixelSize; fromIndex *= pixelSize; if (pixelSize < 8) /* Sub-byte */ { /* Mask to select the location of the copied pixel: */ unsigned int destMask = ((1U<<pixelSize)-1) << (8-pixelSize-(toIndex&7)); /* The following read the entire pixels and clears the extra: */ unsigned int destByte = toBuffer[toIndex >> 3] & ~destMask; unsigned int sourceByte = fromBuffer[fromIndex >> 3];
/* Don't rely on << or >> supporting '0' here, just in case: */ fromIndex &= 7; if (fromIndex > 0) sourceByte <<= fromIndex; if ((toIndex & 7) > 0) sourceByte >>= toIndex & 7;
toBuffer[toIndex >> 3] = (png_byte)(destByte | (sourceByte & destMask)); } else /* One or more bytes */ memmove(toBuffer+(toIndex>>3), fromBuffer+(fromIndex>>3), pixelSize>>3);}
/* Compare pixels - they are assumed to start at the first byte in the
* given buffers. */static intpixel_cmp(png_const_bytep pa, png_const_bytep pb, png_uint_32 bit_width){ if (memcmp(pa, pb, bit_width>>3) == 0) { png_uint_32 p;
if ((bit_width & 7) == 0) return 0;
/* Ok, any differences? */ p = pa[bit_width >> 3]; p ^= pb[bit_width >> 3];
if (p == 0) return 0;
/* There are, but they may not be significant, remove the bits
* after the end (the low order bits in PNG.) */ bit_width &= 7; p >>= 8-bit_width;
if (p == 0) return 0; }
return 1; /* Different */}
/*************************** BASIC PNG FILE WRITING ***************************//* A png_store takes data from the sequential writer or provides data
* to the sequential reader. It can also store the result of a PNG * write for later retrieval. */#define STORE_BUFFER_SIZE 500 /* arbitrary */
typedef struct png_store_buffer{ struct png_store_buffer* prev; /* NOTE: stored in reverse order */ png_byte buffer[STORE_BUFFER_SIZE];} png_store_buffer;
#define FILE_NAME_SIZE 64
typedef struct png_store_file{ struct png_store_file* next; /* as many as you like... */ char name[FILE_NAME_SIZE]; png_uint_32 id; /* must be correct (see FILEID) */ png_size_t datacount; /* In this (the last) buffer */ png_store_buffer data; /* Last buffer in file */} png_store_file;
/* The following is a pool of memory allocated by a single libpng read or write
* operation. */typedef struct store_pool{ struct png_store *store; /* Back pointer */ struct store_memory *list; /* List of allocated memory */ png_byte mark[4]; /* Before and after data */
/* Statistics for this run. */ png_alloc_size_t max; /* Maximum single allocation */ png_alloc_size_t current; /* Current allocation */ png_alloc_size_t limit; /* Highest current allocation */ png_alloc_size_t total; /* Total allocation */
/* Overall statistics (retained across successive runs). */ png_alloc_size_t max_max; png_alloc_size_t max_limit; png_alloc_size_t max_total;} store_pool;
typedef struct png_store{ /* For cexcept.h exception handling - simply store one of these;
* the context is a self pointer but it may point to a different * png_store (in fact it never does in this program.) */ struct exception_context exception_context;
unsigned int verbose :1; unsigned int treat_warnings_as_errors :1; unsigned int expect_error :1; unsigned int expect_warning :1; unsigned int saw_warning :1; unsigned int speed :1; unsigned int progressive :1; /* use progressive read */ unsigned int validated :1; /* used as a temporary flag */ int nerrors; int nwarnings; char test[128]; /* Name of test */ char error[256];
/* Read fields */ png_structp pread; /* Used to read a saved file */ png_infop piread; png_store_file* current; /* Set when reading */ png_store_buffer* next; /* Set when reading */ png_size_t readpos; /* Position in *next */ png_byte* image; /* Buffer for reading interlaced images */ size_t cb_image; /* Size of this buffer */ store_pool read_memory_pool;
/* Write fields */ png_store_file* saved; png_structp pwrite; /* Used when writing a new file */ png_infop piwrite; png_size_t writepos; /* Position in .new */ char wname[FILE_NAME_SIZE]; png_store_buffer new; /* The end of the new PNG file being written. */ store_pool write_memory_pool;} png_store;
/* Initialization and cleanup */static voidstore_pool_mark(png_byte *mark){ /* Generate a new mark. This uses a boring repeatable algorithm and it is
* implemented here so that it gives the same set of numbers on every * architecture. It's a linear congruential generator (Knuth or Sedgewick * "Algorithms") but it comes from the 'feedback taps' table in Horowitz and * Hill, "The Art of Electronics". */ static png_uint_32 u0 = 0x12345678, u1 = 1;
/* There are thirty three bits, the next bit in the sequence is bit-33 XOR
* bit-20. The top 1 bit is in u1, the bottom 32 are in u0. */ int i; for (i=0; i<4; ++i) { /* First generate 8 new bits then shift them in at the end. */ png_uint_32 u = ((u0 >> (20-8)) ^ ((u1 << 7) | (u0 >> (32-7)))) & 0xff; u1 <<= 8; u1 |= u0 >> 24; u0 <<= 8; u0 |= u; *mark++ = (png_byte)u; }}
/* Use this for random 32 bit values, this function makes sure the result is
* non-zero. */static png_uint_32random_32(void){
for(;;) { png_byte mark[4]; png_uint_32 result;
store_pool_mark(mark); result = png_get_uint_32(mark);
if (result != 0) return result; }}
static voidstore_pool_init(png_store *ps, store_pool *pool){ memset(pool, 0, sizeof *pool);
pool->store = ps; pool->list = NULL; pool->max = pool->current = pool->limit = pool->total = 0; pool->max_max = pool->max_limit = pool->max_total = 0; store_pool_mark(pool->mark);}
static voidstore_init(png_store* ps){ memset(ps, 0, sizeof *ps); init_exception_context(&ps->exception_context); store_pool_init(ps, &ps->read_memory_pool); store_pool_init(ps, &ps->write_memory_pool); ps->verbose = 0; ps->treat_warnings_as_errors = 0; ps->expect_error = 0; ps->expect_warning = 0; ps->saw_warning = 0; ps->speed = 0; ps->progressive = 0; ps->validated = 0; ps->nerrors = ps->nwarnings = 0; ps->pread = NULL; ps->piread = NULL; ps->saved = ps->current = NULL; ps->next = NULL; ps->readpos = 0; ps->image = NULL; ps->cb_image = 0; ps->pwrite = NULL; ps->piwrite = NULL; ps->writepos = 0; ps->new.prev = NULL;}
/* This somewhat odd function is used when reading an image to ensure that the
* buffer is big enough - this is why a png_structp is available. */static voidstore_ensure_image(png_store *ps, png_structp pp, size_t cb){ if (ps->cb_image < cb) { if (ps->image != NULL) { free(ps->image-1); ps->cb_image = 0; }
/* The buffer is deliberately mis-aligned. */ ps->image = malloc(cb+1); if (ps->image == NULL) png_error(pp, "OOM allocating image buffer");
++(ps->image); ps->cb_image = cb; }
/* And, for error checking, the whole buffer is set to '1' - this
* matches what happens with the 'size' test images on write and also * matches the unused bits in the test rows. */ memset(ps->image, 0xff, cb);}
static voidstore_freebuffer(png_store_buffer* psb){ if (psb->prev) { store_freebuffer(psb->prev); free(psb->prev); psb->prev = NULL; }}
static voidstore_freenew(png_store *ps){ store_freebuffer(&ps->new); ps->writepos = 0;}
static voidstore_storenew(png_store *ps){ png_store_buffer *pb;
if (ps->writepos != STORE_BUFFER_SIZE) png_error(ps->pwrite, "invalid store call");
pb = malloc(sizeof *pb);
if (pb == NULL) png_error(ps->pwrite, "store new: OOM");
*pb = ps->new; ps->new.prev = pb; ps->writepos = 0;}
static voidstore_freefile(png_store_file **ppf){ if (*ppf != NULL) { store_freefile(&(*ppf)->next);
store_freebuffer(&(*ppf)->data); (*ppf)->datacount = 0; free(*ppf); *ppf = NULL; }}
/* Main interface to file storeage, after writing a new PNG file (see the API
* below) call store_storefile to store the result with the given name and id. */static voidstore_storefile(png_store *ps, png_uint_32 id){ png_store_file *pf = malloc(sizeof *pf); if (pf == NULL) png_error(ps->pwrite, "storefile: OOM"); safecat(pf->name, sizeof pf->name, 0, ps->wname); pf->id = id; pf->data = ps->new; pf->datacount = ps->writepos; ps->new.prev = NULL; ps->writepos = 0;
/* And save it. */ pf->next = ps->saved; ps->saved = pf;}
/* Generate an error message (in the given buffer) */static size_tstore_message(png_store *ps, png_structp pp, char *buffer, size_t bufsize, size_t pos, PNG_CONST char *msg){ if (pp != NULL && pp == ps->pread) { /* Reading a file */ pos = safecat(buffer, bufsize, pos, "read: ");
if (ps->current != NULL) { pos = safecat(buffer, bufsize, pos, ps->current->name); pos = safecat(buffer, bufsize, pos, sep); } }
else if (pp != NULL && pp == ps->pwrite) { /* Writing a file */ pos = safecat(buffer, bufsize, pos, "write: "); pos = safecat(buffer, bufsize, pos, ps->wname); pos = safecat(buffer, bufsize, pos, sep); }
else { /* Neither reading nor writing (or a memory error in struct delete) */ pos = safecat(buffer, bufsize, pos, "pngvalid: "); }
if (ps->test[0] != 0) { pos = safecat(buffer, bufsize, pos, ps->test); pos = safecat(buffer, bufsize, pos, sep); } pos = safecat(buffer, bufsize, pos, msg); return pos;}
/* Log an error or warning - the relevant count is always incremented. */static voidstore_log(png_store* ps, png_structp pp, png_const_charp message, int is_error){ /* The warning is copied to the error buffer if there are no errors and it is
* the first warning. The error is copied to the error buffer if it is the * first error (overwriting any prior warnings). */ if (is_error ? (ps->nerrors)++ == 0 : (ps->nwarnings)++ == 0 && ps->nerrors == 0) store_message(ps, pp, ps->error, sizeof ps->error, 0, message);
if (ps->verbose) { char buffer[256]; size_t pos;
if (is_error) pos = safecat(buffer, sizeof buffer, 0, "error: "); else pos = safecat(buffer, sizeof buffer, 0, "warning: ");
store_message(ps, pp, buffer, sizeof buffer, pos, message); fputs(buffer, stderr); fputc('\n', stderr); }}
/* Functions to use as PNG callbacks. */static voidstore_error(png_structp pp, png_const_charp message) /* PNG_NORETURN */{ png_store *ps = png_get_error_ptr(pp);
if (!ps->expect_error) store_log(ps, pp, message, 1 /* error */);
/* And finally throw an exception. */ { struct exception_context *the_exception_context = &ps->exception_context; Throw ps; }}
static voidstore_warning(png_structp pp, png_const_charp message){ png_store *ps = png_get_error_ptr(pp);
if (!ps->expect_warning) store_log(ps, pp, message, 0 /* warning */); else ps->saw_warning = 1;}
static voidstore_write(png_structp pp, png_bytep pb, png_size_t st){ png_store *ps = png_get_io_ptr(pp);
if (ps->pwrite != pp) png_error(pp, "store state damaged");
while (st > 0) { size_t cb;
if (ps->writepos >= STORE_BUFFER_SIZE) store_storenew(ps);
cb = st;
if (cb > STORE_BUFFER_SIZE - ps->writepos) cb = STORE_BUFFER_SIZE - ps->writepos;
memcpy(ps->new.buffer + ps->writepos, pb, cb); pb += cb; st -= cb; ps->writepos += cb; }}
static voidstore_flush(png_structp pp){ UNUSED(pp) /*DOES NOTHING*/}
static size_tstore_read_buffer_size(png_store *ps){ /* Return the bytes available for read in the current buffer. */ if (ps->next != &ps->current->data) return STORE_BUFFER_SIZE;
return ps->current->datacount;}
/* Return total bytes available for read. */static size_tstore_read_buffer_avail(png_store *ps){ if (ps->current != NULL && ps->next != NULL) { png_store_buffer *next = &ps->current->data; size_t cbAvail = ps->current->datacount;
while (next != ps->next && next != NULL) { next = next->prev; cbAvail += STORE_BUFFER_SIZE; }
if (next != ps->next) png_error(ps->pread, "buffer read error");
if (cbAvail > ps->readpos) return cbAvail - ps->readpos; }
return 0;}
static intstore_read_buffer_next(png_store *ps){ png_store_buffer *pbOld = ps->next; png_store_buffer *pbNew = &ps->current->data; if (pbOld != pbNew) { while (pbNew != NULL && pbNew->prev != pbOld) pbNew = pbNew->prev;
if (pbNew != NULL) { ps->next = pbNew; ps->readpos = 0; return 1; }
png_error(ps->pread, "buffer lost"); }
return 0; /* EOF or error */}
/* Need separate implementation and callback to allow use of the same code
* during progressive read, where the io_ptr is set internally by libpng. */static voidstore_read_imp(png_store *ps, png_bytep pb, png_size_t st){ if (ps->current == NULL || ps->next == NULL) png_error(ps->pread, "store state damaged");
while (st > 0) { size_t cbAvail = store_read_buffer_size(ps) - ps->readpos;
if (cbAvail > 0) { if (cbAvail > st) cbAvail = st; memcpy(pb, ps->next->buffer + ps->readpos, cbAvail); st -= cbAvail; pb += cbAvail; ps->readpos += cbAvail; }
else if (!store_read_buffer_next(ps)) png_error(ps->pread, "read beyond end of file"); }}
static voidstore_read(png_structp pp, png_bytep pb, png_size_t st){ png_store *ps = png_get_io_ptr(pp);
if (ps == NULL || ps->pread != pp) png_error(pp, "bad store read call");
store_read_imp(ps, pb, st);}
static voidstore_progressive_read(png_store *ps, png_structp pp, png_infop pi){ /* Notice that a call to store_read will cause this function to fail because
* readpos will be set. */ if (ps->pread != pp || ps->current == NULL || ps->next == NULL) png_error(pp, "store state damaged (progressive)");
do { if (ps->readpos != 0) png_error(pp, "store_read called during progressive read");
png_process_data(pp, pi, ps->next->buffer, store_read_buffer_size(ps)); } while (store_read_buffer_next(ps));}
/***************************** MEMORY MANAGEMENT*** ***************************//* A store_memory is simply the header for an allocated block of memory. The
* pointer returned to libpng is just after the end of the header block, the * allocated memory is followed by a second copy of the 'mark'. */typedef struct store_memory{ store_pool *pool; /* Originating pool */ struct store_memory *next; /* Singly linked list */ png_alloc_size_t size; /* Size of memory allocated */ png_byte mark[4]; /* ID marker */} store_memory;
/* Handle a fatal error in memory allocation. This calls png_error if the
* libpng struct is non-NULL, else it outputs a message and returns. This means * that a memory problem while libpng is running will abort (png_error) the * handling of particular file while one in cleanup (after the destroy of the * struct has returned) will simply keep going and free (or attempt to free) * all the memory. */static voidstore_pool_error(png_store *ps, png_structp pp, PNG_CONST char *msg){ if (pp != NULL) png_error(pp, msg);
/* Else we have to do it ourselves. png_error eventually calls store_log,
* above. store_log accepts a NULL png_structp - it just changes what gets * output by store_message. */ store_log(ps, pp, msg, 1 /* error */);}
static voidstore_memory_free(png_structp pp, store_pool *pool, store_memory *memory){ /* Note that pp may be NULL (see store_pool_delete below), the caller has
* found 'memory' in pool->list *and* unlinked this entry, so this is a valid * pointer (for sure), but the contents may have been trashed. */ if (memory->pool != pool) store_pool_error(pool->store, pp, "memory corrupted (pool)");
else if (memcmp(memory->mark, pool->mark, sizeof memory->mark) != 0) store_pool_error(pool->store, pp, "memory corrupted (start)");
/* It should be safe to read the size field now. */ else { png_alloc_size_t cb = memory->size;
if (cb > pool->max) store_pool_error(pool->store, pp, "memory corrupted (size)");
else if (memcmp((png_bytep)(memory+1)+cb, pool->mark, sizeof pool->mark) != 0) store_pool_error(pool->store, pp, "memory corrupted (end)");
/* Finally give the library a chance to find problems too: */ else { pool->current -= cb; free(memory); } }}
static voidstore_pool_delete(png_store *ps, store_pool *pool){ if (pool->list != NULL) { fprintf(stderr, "%s: %s %s: memory lost (list follows):\n", ps->test, pool == &ps->read_memory_pool ? "read" : "write", pool == &ps->read_memory_pool ? (ps->current != NULL ? ps->current->name : "unknown file") : ps->wname); ++ps->nerrors;
do { store_memory *next = pool->list; pool->list = next->next; next->next = NULL;
fprintf(stderr, "\t%lu bytes @ %p\n", (unsigned long)next->size, (PNG_CONST void*)(next+1)); /* The NULL means this will always return, even if the memory is
* corrupted. */ store_memory_free(NULL, pool, next); } while (pool->list != NULL); }
/* And reset the other fields too for the next time. */ if (pool->max > pool->max_max) pool->max_max = pool->max; pool->max = 0; if (pool->current != 0) /* unexpected internal error */ fprintf(stderr, "%s: %s %s: memory counter mismatch (internal error)\n", ps->test, pool == &ps->read_memory_pool ? "read" : "write", pool == &ps->read_memory_pool ? (ps->current != NULL ? ps->current->name : "unknown file") : ps->wname); pool->current = 0;
if (pool->limit > pool->max_limit) pool->max_limit = pool->limit;
pool->limit = 0;
if (pool->total > pool->max_total) pool->max_total = pool->total;
pool->total = 0;
/* Get a new mark too. */ store_pool_mark(pool->mark);}
/* The memory callbacks: */static png_voidpstore_malloc(png_structp pp, png_alloc_size_t cb){ store_pool *pool = png_get_mem_ptr(pp); store_memory *new = malloc(cb + (sizeof *new) + (sizeof pool->mark));
if (new != NULL) { if (cb > pool->max) pool->max = cb;
pool->current += cb;
if (pool->current > pool->limit) pool->limit = pool->current;
pool->total += cb;
new->size = cb; memcpy(new->mark, pool->mark, sizeof new->mark); memcpy((png_byte*)(new+1) + cb, pool->mark, sizeof pool->mark); new->pool = pool; new->next = pool->list; pool->list = new; ++new; }
else store_pool_error(pool->store, pp, "out of memory");
return new;}
static voidstore_free(png_structp pp, png_voidp memory){ store_pool *pool = png_get_mem_ptr(pp); store_memory *this = memory, **test;
/* First check that this 'memory' really is valid memory - it must be in the
* pool list. If it is, use the shared memory_free function to free it. */ --this; for (test = &pool->list; *test != this; test = &(*test)->next) { if (*test == NULL) { store_pool_error(pool->store, pp, "bad pointer to free"); return; } }
/* Unlink this entry, *test == this. */ *test = this->next; this->next = NULL; store_memory_free(pp, pool, this);}
/* Setup functions. *//* Cleanup when aborting a write or after storing the new file. */static voidstore_write_reset(png_store *ps){ if (ps->pwrite != NULL) { anon_context(ps);
Try png_destroy_write_struct(&ps->pwrite, &ps->piwrite);
Catch_anonymous { /* memory corruption: continue. */ }
ps->pwrite = NULL; ps->piwrite = NULL; }
/* And make sure that all the memory has been freed - this will output
* spurious errors in the case of memory corruption above, but this is safe. */ store_pool_delete(ps, &ps->write_memory_pool);
store_freenew(ps);}
/* The following is the main write function, it returns a png_struct and,
* optionally, a png_info suitable for writiing a new PNG file. Use * store_storefile above to record this file after it has been written. The * returned libpng structures as destroyed by store_write_reset above. */static png_structpset_store_for_write(png_store *ps, png_infopp ppi, PNG_CONST char * volatile name){ anon_context(ps);
Try { if (ps->pwrite != NULL) png_error(ps->pwrite, "write store already in use");
store_write_reset(ps); safecat(ps->wname, sizeof ps->wname, 0, name);
/* Don't do the slow memory checks if doing a speed test. */ if (ps->speed) ps->pwrite = png_create_write_struct(PNG_LIBPNG_VER_STRING, ps, store_error, store_warning);
else ps->pwrite = png_create_write_struct_2(PNG_LIBPNG_VER_STRING, ps, store_error, store_warning, &ps->write_memory_pool, store_malloc, store_free);
png_set_write_fn(ps->pwrite, ps, store_write, store_flush);
if (ppi != NULL) *ppi = ps->piwrite = png_create_info_struct(ps->pwrite); }
Catch_anonymous return NULL;
return ps->pwrite;}
/* Cleanup when finished reading (either due to error or in the success case).
*/static voidstore_read_reset(png_store *ps){ if (ps->pread != NULL) { anon_context(ps);
Try png_destroy_read_struct(&ps->pread, &ps->piread, NULL);
Catch_anonymous { /* error already output: continue */ }
ps->pread = NULL; ps->piread = NULL; }
/* Always do this to be safe. */ store_pool_delete(ps, &ps->read_memory_pool);
ps->current = NULL; ps->next = NULL; ps->readpos = 0; ps->validated = 0;}
static voidstore_read_set(png_store *ps, png_uint_32 id){ png_store_file *pf = ps->saved;
while (pf != NULL) { if (pf->id == id) { ps->current = pf; ps->next = NULL; store_read_buffer_next(ps); return; }
pf = pf->next; }
{ size_t pos; char msg[FILE_NAME_SIZE+64];
pos = standard_name_from_id(msg, sizeof msg, 0, id); pos = safecat(msg, sizeof msg, pos, ": file not found"); png_error(ps->pread, msg); }}
/* The main interface for reading a saved file - pass the id number of the file
* to retrieve. Ids must be unique or the earlier file will be hidden. The API * returns a png_struct and, optionally, a png_info. Both of these will be * destroyed by store_read_reset above. */static png_structpset_store_for_read(png_store *ps, png_infopp ppi, png_uint_32 id, PNG_CONST char *name){ /* Set the name for png_error */ safecat(ps->test, sizeof ps->test, 0, name);
if (ps->pread != NULL) png_error(ps->pread, "read store already in use");
store_read_reset(ps);
/* Both the create APIs can return NULL if used in their default mode
* (because there is no other way of handling an error because the jmp_buf * by default is stored in png_struct and that has not been allocated!) * However, given that store_error works correctly in these circumstances * we don't ever expect NULL in this program. */ if (ps->speed) ps->pread = png_create_read_struct(PNG_LIBPNG_VER_STRING, ps, store_error, store_warning);
else ps->pread = png_create_read_struct_2(PNG_LIBPNG_VER_STRING, ps, store_error, store_warning, &ps->read_memory_pool, store_malloc, store_free);
if (ps->pread == NULL) { struct exception_context *the_exception_context = &ps->exception_context;
store_log(ps, NULL, "png_create_read_struct returned NULL (unexpected)", 1 /*error*/);
Throw ps; }
store_read_set(ps, id);
if (ppi != NULL) *ppi = ps->piread = png_create_info_struct(ps->pread);
return ps->pread;}
/* The overall cleanup of a store simply calls the above then removes all the
* saved files. This does not delete the store itself. */static voidstore_delete(png_store *ps){ store_write_reset(ps); store_read_reset(ps); store_freefile(&ps->saved);
if (ps->image != NULL) { free(ps->image-1); ps->image = NULL; ps->cb_image = 0; }}
/*********************** PNG FILE MODIFICATION ON READ ************************//* Files may be modified on read. The following structure contains a complete
* png_store together with extra members to handle modification and a special * read callback for libpng. To use this the 'modifications' field must be set * to a list of png_modification structures that actually perform the * modification, otherwise a png_modifier is functionally equivalent to a * png_store. There is a special read function, set_modifier_for_read, which * replaces set_store_for_read. */typedef struct png_modifier{ png_store this; /* I am a png_store */ struct png_modification *modifications; /* Changes to make */
enum modifier_state { modifier_start, /* Initial value */ modifier_signature, /* Have a signature */ modifier_IHDR /* Have an IHDR */ } state; /* My state */
/* Information from IHDR: */ png_byte bit_depth; /* From IHDR */ png_byte colour_type; /* From IHDR */
/* While handling PLTE, IDAT and IEND these chunks may be pended to allow
* other chunks to be inserted. */ png_uint_32 pending_len; png_uint_32 pending_chunk;
/* Test values */ double *gammas; unsigned int ngammas;
/* Lowest sbit to test (libpng fails for sbit < 8) */ png_byte sbitlow;
/* Error control - these are the limits on errors accepted by the gamma tests
* below. */ double maxout8; /* Maximum output value error */ double maxabs8; /* Absolute sample error 0..1 */ double maxpc8; /* Percentage sample error 0..100% */ double maxout16; /* Maximum output value error */ double maxabs16; /* Absolute sample error 0..1 */ double maxpc16; /* Percentage sample error 0..100% */
/* Logged 8 and 16 bit errors ('output' values): */ double error_gray_2; double error_gray_4; double error_gray_8; double error_gray_16; double error_color_8; double error_color_16;
/* Flags: */ /* Whether or not to interlace. */ int interlace_type :9; /* int, but must store '1' */
/* Run the standard tests? */ unsigned int test_standard :1;
/* Run the odd-sized image and interlace read/write tests? */ unsigned int test_size :1;
/* Run tests on reading with a combiniation of transforms, */ unsigned int test_transform :1;
/* When to use the use_input_precision option: */ unsigned int use_input_precision :1; unsigned int use_input_precision_sbit :1; unsigned int use_input_precision_16to8 :1;
/* Which gamma tests to run: */ unsigned int test_gamma_threshold :1; unsigned int test_gamma_transform :1; /* main tests */ unsigned int test_gamma_sbit :1; unsigned int test_gamma_strip16 :1;
unsigned int log :1; /* Log max error */
/* Buffer information, the buffer size limits the size of the chunks that can
* be modified - they must fit (including header and CRC) into the buffer! */ size_t flush; /* Count of bytes to flush */ size_t buffer_count; /* Bytes in buffer */ size_t buffer_position; /* Position in buffer */ png_byte buffer[1024];} png_modifier;
static double abserr(png_modifier *pm, png_byte bit_depth){ return bit_depth == 16 ? pm->maxabs16 : pm->maxabs8;}
static double pcerr(png_modifier *pm, png_byte bit_depth){ return (bit_depth == 16 ? pm->maxpc16 : pm->maxpc8) * .01;}
static double outerr(png_modifier *pm, png_byte bit_depth){ /* There is a serious error in the 2 and 4 bit grayscale transform because
* the gamma table value (8 bits) is simply shifted, not rounded, so the * error in 4 bit greyscale gamma is up to the value below. This is a hack * to allow pngvalid to succeed: */ if (bit_depth == 2) return .73182-.5;
if (bit_depth == 4) return .90644-.5;
if (bit_depth == 16) return pm->maxout16;
return pm->maxout8;}
/* This returns true if the test should be stopped now because it has already
* failed and it is running silently. */static int fail(png_modifier *pm){ return !pm->log && !pm->this.verbose && (pm->this.nerrors > 0 || (pm->this.treat_warnings_as_errors && pm->this.nwarnings > 0));}
static voidmodifier_init(png_modifier *pm){ memset(pm, 0, sizeof *pm); store_init(&pm->this); pm->modifications = NULL; pm->state = modifier_start; pm->sbitlow = 1U; pm->maxout8 = pm->maxpc8 = pm->maxabs8 = 0; pm->maxout16 = pm->maxpc16 = pm->maxabs16 = 0; pm->error_gray_2 = pm->error_gray_4 = pm->error_gray_8 = 0; pm->error_gray_16 = pm->error_color_8 = pm->error_color_16 = 0; pm->interlace_type = PNG_INTERLACE_NONE; pm->test_standard = 0; pm->test_size = 0; pm->test_transform = 0; pm->use_input_precision = 0; pm->use_input_precision_sbit = 0; pm->use_input_precision_16to8 = 0; pm->test_gamma_threshold = 0; pm->test_gamma_transform = 0; pm->test_gamma_sbit = 0; pm->test_gamma_strip16 = 0; pm->log = 0;
/* Rely on the memset for all the other fields - there are no pointers */}
/* One modification structure must be provided for each chunk to be modified (in
* fact more than one can be provided if multiple separate changes are desired * for a single chunk.) Modifications include adding a new chunk when a * suitable chunk does not exist. * * The caller of modify_fn will reset the CRC of the chunk and record 'modified' * or 'added' as appropriate if the modify_fn returns 1 (true). If the * modify_fn is NULL the chunk is simply removed. */typedef struct png_modification{ struct png_modification *next; png_uint_32 chunk;
/* If the following is NULL all matching chunks will be removed: */ int (*modify_fn)(struct png_modifier *pm, struct png_modification *me, int add);
/* If the following is set to PLTE, IDAT or IEND and the chunk has not been
* found and modified (and there is a modify_fn) the modify_fn will be called * to add the chunk before the relevant chunk. */ png_uint_32 add; unsigned int modified :1; /* Chunk was modified */ unsigned int added :1; /* Chunk was added */ unsigned int removed :1; /* Chunk was removed */} png_modification;
static void modification_reset(png_modification *pmm){ if (pmm != NULL) { pmm->modified = 0; pmm->added = 0; pmm->removed = 0; modification_reset(pmm->next); }}
static voidmodification_init(png_modification *pmm){ memset(pmm, 0, sizeof *pmm); pmm->next = NULL; pmm->chunk = 0; pmm->modify_fn = NULL; pmm->add = 0; modification_reset(pmm);}
static voidmodifier_reset(png_modifier *pm){ store_read_reset(&pm->this); pm->modifications = NULL; pm->state = modifier_start; pm->bit_depth = pm->colour_type = 0; pm->pending_len = pm->pending_chunk = 0; pm->flush = pm->buffer_count = pm->buffer_position = 0;}
/* Convenience macros. */#define CHUNK(a,b,c,d) (((a)<<24)+((b)<<16)+((c)<<8)+(d))
#define CHUNK_IHDR CHUNK(73,72,68,82)
#define CHUNK_PLTE CHUNK(80,76,84,69)
#define CHUNK_IDAT CHUNK(73,68,65,84)
#define CHUNK_IEND CHUNK(73,69,78,68)
#define CHUNK_cHRM CHUNK(99,72,82,77)
#define CHUNK_gAMA CHUNK(103,65,77,65)
#define CHUNK_sBIT CHUNK(115,66,73,84)
#define CHUNK_sRGB CHUNK(115,82,71,66)
/* The guts of modification are performed during a read. */static voidmodifier_crc(png_bytep buffer){ /* Recalculate the chunk CRC - a complete chunk must be in
* the buffer, at the start. */ uInt datalen = png_get_uint_32(buffer); png_save_uint_32(buffer+datalen+8, crc32(0L, buffer+4, datalen+4));}
static voidmodifier_setbuffer(png_modifier *pm){ modifier_crc(pm->buffer); pm->buffer_count = png_get_uint_32(pm->buffer)+12; pm->buffer_position = 0;}
/* Separate the callback into the actual implementation (which is passed the
* png_modifier explicitly) and the callback, which gets the modifier from the * png_struct. */static voidmodifier_read_imp(png_modifier *pm, png_bytep pb, png_size_t st){ while (st > 0) { size_t cb; png_uint_32 len, chunk; png_modification *mod;
if (pm->buffer_position >= pm->buffer_count) switch (pm->state) { static png_byte sign[8] = { 137, 80, 78, 71, 13, 10, 26, 10 }; case modifier_start: store_read_imp(&pm->this, pm->buffer, 8); /* size of signature. */ pm->buffer_count = 8; pm->buffer_position = 0;
if (memcmp(pm->buffer, sign, 8) != 0) png_error(pm->this.pread, "invalid PNG file signature"); pm->state = modifier_signature; break;
case modifier_signature: store_read_imp(&pm->this, pm->buffer, 13+12); /* size of IHDR */ pm->buffer_count = 13+12; pm->buffer_position = 0;
if (png_get_uint_32(pm->buffer) != 13 || png_get_uint_32(pm->buffer+4) != CHUNK_IHDR) png_error(pm->this.pread, "invalid IHDR");
/* Check the list of modifiers for modifications to the IHDR. */ mod = pm->modifications; while (mod != NULL) { if (mod->chunk == CHUNK_IHDR && mod->modify_fn && (*mod->modify_fn)(pm, mod, 0)) { mod->modified = 1; modifier_setbuffer(pm); }
/* Ignore removal or add if IHDR! */ mod = mod->next; }
/* Cache information from the IHDR (the modified one.) */ pm->bit_depth = pm->buffer[8+8]; pm->colour_type = pm->buffer[8+8+1];
pm->state = modifier_IHDR; pm->flush = 0; break;
case modifier_IHDR: default: /* Read a new chunk and process it until we see PLTE, IDAT or
* IEND. 'flush' indicates that there is still some data to * output from the preceding chunk. */ if ((cb = pm->flush) > 0) { if (cb > st) cb = st; pm->flush -= cb; store_read_imp(&pm->this, pb, cb); pb += cb; st -= cb; if (st <= 0) return; }
/* No more bytes to flush, read a header, or handle a pending
* chunk. */ if (pm->pending_chunk != 0) { png_save_uint_32(pm->buffer, pm->pending_len); png_save_uint_32(pm->buffer+4, pm->pending_chunk); pm->pending_len = 0; pm->pending_chunk = 0; } else store_read_imp(&pm->this, pm->buffer, 8);
pm->buffer_count = 8; pm->buffer_position = 0;
/* Check for something to modify or a terminator chunk. */ len = png_get_uint_32(pm->buffer); chunk = png_get_uint_32(pm->buffer+4);
/* Terminators first, they may have to be delayed for added
* chunks */ if (chunk == CHUNK_PLTE || chunk == CHUNK_IDAT || chunk == CHUNK_IEND) { mod = pm->modifications;
while (mod != NULL) { if ((mod->add == chunk || (mod->add == CHUNK_PLTE && chunk == CHUNK_IDAT)) && mod->modify_fn != NULL && !mod->modified && !mod->added) { /* Regardless of what the modify function does do not run
* this again. */ mod->added = 1;
if ((*mod->modify_fn)(pm, mod, 1 /*add*/)) { /* Reset the CRC on a new chunk */ if (pm->buffer_count > 0) modifier_setbuffer(pm);
else { pm->buffer_position = 0; mod->removed = 1; }
/* The buffer has been filled with something (we assume)
* so output this. Pend the current chunk. */ pm->pending_len = len; pm->pending_chunk = chunk; break; /* out of while */ } }
mod = mod->next; }
/* Don't do any further processing if the buffer was modified -
* otherwise the code will end up modifying a chunk that was * just added. */ if (mod != NULL) break; /* out of switch */ }
/* If we get to here then this chunk may need to be modified. To
* do this it must be less than 1024 bytes in total size, otherwise * it just gets flushed. */ if (len+12 <= sizeof pm->buffer) { store_read_imp(&pm->this, pm->buffer+pm->buffer_count, len+12-pm->buffer_count); pm->buffer_count = len+12;
/* Check for a modification, else leave it be. */ mod = pm->modifications; while (mod != NULL) { if (mod->chunk == chunk) { if (mod->modify_fn == NULL) { /* Remove this chunk */ pm->buffer_count = pm->buffer_position = 0; mod->removed = 1; break; /* Terminate the while loop */ }
else if ((*mod->modify_fn)(pm, mod, 0)) { mod->modified = 1; /* The chunk may have been removed: */ if (pm->buffer_count == 0) { pm->buffer_position = 0; break; } modifier_setbuffer(pm); } }
mod = mod->next; } }
else pm->flush = len+12 - pm->buffer_count; /* data + crc */
/* Take the data from the buffer (if there is any). */ break; }
/* Here to read from the modifier buffer (not directly from
* the store, as in the flush case above.) */ cb = pm->buffer_count - pm->buffer_position;
if (cb > st) cb = st;
memcpy(pb, pm->buffer + pm->buffer_position, cb); st -= cb; pb += cb; pm->buffer_position += cb; }}
/* The callback: */static voidmodifier_read(png_structp pp, png_bytep pb, png_size_t st){ png_modifier *pm = png_get_io_ptr(pp);
if (pm == NULL || pm->this.pread != pp) png_error(pp, "bad modifier_read call");
modifier_read_imp(pm, pb, st);}
/* Like store_progressive_read but the data is getting changed as we go so we
* need a local buffer. */static voidmodifier_progressive_read(png_modifier *pm, png_structp pp, png_infop pi){ if (pm->this.pread != pp || pm->this.current == NULL || pm->this.next == NULL) png_error(pp, "store state damaged (progressive)");
/* This is another Horowitz and Hill random noise generator. In this case
* the aim is to stress the progressive reader with truely horrible variable * buffer sizes in the range 1..500, so a sequence of 9 bit random numbers * is generated. We could probably just count from 1 to 32767 and get as * good a result. */ for (;;) { static png_uint_32 noise = 1; png_size_t cb, cbAvail; png_byte buffer[512];
/* Generate 15 more bits of stuff: */ noise = (noise << 9) | ((noise ^ (noise >> (9-5))) & 0x1ff); cb = noise & 0x1ff;
/* Check that this number of bytes are available (in the current buffer.)
* (This doesn't quite work - the modifier might delete a chunk; unlikely * but possible, it doesn't happen at present because the modifier only * adds chunks to standard images.) */ cbAvail = store_read_buffer_avail(&pm->this); if (pm->buffer_count > pm->buffer_position) cbAvail += pm->buffer_count - pm->buffer_position;
if (cb > cbAvail) { /* Check for EOF: */ if (cbAvail == 0) break;
cb = cbAvail; }
modifier_read_imp(pm, buffer, cb); png_process_data(pp, pi, buffer, cb); }
/* Check the invariants at the end (if this fails it's a problem in this
* file!) */ if (pm->buffer_count > pm->buffer_position || pm->this.next != &pm->this.current->data || pm->this.readpos < pm->this.current->datacount) png_error(pp, "progressive read implementation error");}
/* Set up a modifier. */static png_structpset_modifier_for_read(png_modifier *pm, png_infopp ppi, png_uint_32 id, PNG_CONST char *name){ /* Do this first so that the modifier fields are cleared even if an error
* happens allocating the png_struct. No allocation is done here so no * cleanup is required. */ pm->state = modifier_start; pm->bit_depth = 0; pm->colour_type = 255;
pm->pending_len = 0; pm->pending_chunk = 0; pm->flush = 0; pm->buffer_count = 0; pm->buffer_position = 0;
return set_store_for_read(&pm->this, ppi, id, name);}
/***************************** STANDARD PNG FILES *****************************//* Standard files - write and save standard files. *//* There are two basic forms of standard images. Those which attempt to have
* all the possible pixel values (not possible for 16bpp images, but a range of * values are produced) and those which have a range of image sizes. The former * are used for testing transforms, in particular gamma correction and bit * reduction and increase. The latter are reserved for testing the behavior of * libpng with respect to 'odd' image sizes - particularly small images where * rows become 1 byte and interlace passes disappear. * * The first, most useful, set are the 'transform' images, the second set of * small images are the 'size' images. * * The transform files are constructed with rows which fit into a 1024 byte row * buffer. This makes allocation easier below. Further regardless of the file * format every row has 128 pixels (giving 1024 bytes for 64bpp formats). * * Files are stored with no gAMA or sBIT chunks, with a PLTE only when needed * and with an ID derived from the colour type, bit depth and interlace type * as above (FILEID). The width (128) and height (variable) are not stored in * the FILEID - instead the fields are set to 0, indicating a transform file. * * The size files ar constructed with rows a maximum of 128 bytes wide, allowing * a maximum width of 16 pixels (for the 64bpp case.) They also have a maximum * height of 16 rows. The width and height are stored in the FILEID and, being * non-zero, indicate a size file. */
/* The number of passes is related to the interlace type. There wass no libpng
* API to determine this prior to 1.5, so we need an inquiry function: */static intnpasses_from_interlace_type(png_structp pp, int interlace_type){ switch (interlace_type) { default: png_error(pp, "invalid interlace type");
case PNG_INTERLACE_NONE: return 1;
case PNG_INTERLACE_ADAM7: return PNG_INTERLACE_ADAM7_PASSES; }}
static unsigned intbit_size(png_structp pp, png_byte colour_type, png_byte bit_depth){ switch (colour_type) { case 0: return bit_depth;
case 2: return 3*bit_depth;
case 3: return bit_depth;
case 4: return 2*bit_depth;
case 6: return 4*bit_depth;
default: png_error(pp, "invalid color type"); }}
#define TRANSFORM_WIDTH 128U
#define TRANSFORM_ROWMAX (TRANSFORM_WIDTH*8U)
#define SIZE_ROWMAX (16*8U) /* 16 pixels, max 8 bytes each - 128 bytes */
#define STANDARD_ROWMAX TRANSFORM_ROWMAX /* The larger of the two */
/* So the maximum image sizes are as follows. A 'transform' image may require
* more than 65535 bytes. The size images are a maximum of 2046 bytes. */#define TRANSFORM_IMAGEMAX (TRANSFORM_ROWMAX * (png_uint_32)2048)
#define SIZE_IMAGEMAX (SIZE_ROWMAX * 16U)
static size_ttransform_rowsize(png_structp pp, png_byte colour_type, png_byte bit_depth){ return (TRANSFORM_WIDTH * bit_size(pp, colour_type, bit_depth)) / 8;}
/* transform_width(pp, colour_type, bit_depth) current returns the same number
* every time, so just use a macro: */#define transform_width(pp, colour_type, bit_depth) TRANSFORM_WIDTH
static png_uint_32transform_height(png_structp pp, png_byte colour_type, png_byte bit_depth){ switch (bit_size(pp, colour_type, bit_depth)) { case 1: case 2: case 4: return 1; /* Total of 128 pixels */
case 8: return 2; /* Total of 256 pixels/bytes */
case 16: return 512; /* Total of 65536 pixels */
case 24: case 32: return 512; /* 65536 pixels */
case 48: case 64: return 2048;/* 4 x 65536 pixels. */
default: return 0; /* Error, will be caught later */ }}
/* The following can only be defined here, now we have the definitions
* of the transform image sizes. */static png_uint_32standard_width(png_structp pp, png_uint_32 id){ png_uint_32 width = WIDTH_FROM_ID(id); UNUSED(pp)
if (width == 0) width = transform_width(pp, COL_FROM_ID(id), DEPTH_FROM_ID(id));
return width;}
static png_uint_32standard_height(png_structp pp, png_uint_32 id){ png_uint_32 height = HEIGHT_FROM_ID(id);
if (height == 0) height = transform_height(pp, COL_FROM_ID(id), DEPTH_FROM_ID(id));
return height;}
static png_uint_32standard_rowsize(png_structp pp, png_uint_32 id){ png_uint_32 width = standard_width(pp, id);
/* This won't overflow: */ width *= bit_size(pp, COL_FROM_ID(id), DEPTH_FROM_ID(id)); return (width + 7) / 8;}
static voidtransform_row(png_structp pp, png_byte buffer[TRANSFORM_ROWMAX], png_byte colour_type, png_byte bit_depth, png_uint_32 y){ png_uint_32 v = y << 7; png_uint_32 i = 0;
switch (bit_size(pp, colour_type, bit_depth)) { case 1: while (i<128/8) buffer[i] = v & 0xff, v += 17, ++i; return;
case 2: while (i<128/4) buffer[i] = v & 0xff, v += 33, ++i; return;
case 4: while (i<128/2) buffer[i] = v & 0xff, v += 65, ++i; return;
case 8: /* 256 bytes total, 128 bytes in each row set as follows: */ while (i<128) buffer[i] = v & 0xff, ++v, ++i; return;
case 16: /* Generate all 65536 pixel values in order, which includes the 8 bit
* GA case as well as the 16 bit G case. */ while (i<128) buffer[2*i] = (v>>8) & 0xff, buffer[2*i+1] = v & 0xff, ++v, ++i;
return;
case 24: /* 65535 pixels, but rotate the values. */ while (i<128) { /* Three bytes per pixel, r, g, b, make b by r^g */ buffer[3*i+0] = (v >> 8) & 0xff; buffer[3*i+1] = v & 0xff; buffer[3*i+2] = ((v >> 8) ^ v) & 0xff; ++v; ++i; }
return;
case 32: /* 65535 pixels, r, g, b, a; just replicate */ while (i<128) { buffer[4*i+0] = (v >> 8) & 0xff; buffer[4*i+1] = v & 0xff; buffer[4*i+2] = (v >> 8) & 0xff; buffer[4*i+3] = v & 0xff; ++v; ++i; }
return;
case 48: /* y is maximum 2047, giving 4x65536 pixels, make 'r' increase by 1 at
* each pixel, g increase by 257 (0x101) and 'b' by 0x1111: */ while (i<128) { png_uint_32 t = v++; buffer[6*i+0] = (t >> 8) & 0xff; buffer[6*i+1] = t & 0xff; t *= 257; buffer[6*i+2] = (t >> 8) & 0xff; buffer[6*i+3] = t & 0xff; t *= 17; buffer[6*i+4] = (t >> 8) & 0xff; buffer[6*i+5] = t & 0xff; ++i; }
return;
case 64: /* As above in the 32 bit case. */ while (i<128) { png_uint_32 t = v++; buffer[8*i+0] = (t >> 8) & 0xff; buffer[8*i+1] = t & 0xff; buffer[8*i+4] = (t >> 8) & 0xff; buffer[8*i+5] = t & 0xff; t *= 257; buffer[8*i+2] = (t >> 8) & 0xff; buffer[8*i+3] = t & 0xff; buffer[8*i+6] = (t >> 8) & 0xff; buffer[8*i+7] = t & 0xff; ++i; } return;
default: break; }
png_error(pp, "internal error");}
/* This is just to do the right cast - could be changed to a function to check
* 'bd' but there isn't much point. */#define DEPTH(bd) ((png_byte)(1U << (bd)))
/* Make a standardized image given a an image colour type, bit depth and
* interlace type. The standard images have a very restricted range of * rows and heights and are used for testing transforms rather than image * layout details. See make_size_images below for a way to make images * that test odd sizes along with the libpng interlace handling. */static voidmake_transform_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type, png_byte PNG_CONST bit_depth, int interlace_type, png_const_charp name){ context(ps, fault);
Try { png_infop pi; png_structp pp = set_store_for_write(ps, &pi, name); png_uint_32 h;
/* In the event of a problem return control to the Catch statement below
* to do the clean up - it is not possible to 'return' directly from a Try * block. */ if (pp == NULL) Throw ps;
h = transform_height(pp, colour_type, bit_depth);
png_set_IHDR(pp, pi, transform_width(pp, colour_type, bit_depth), h, bit_depth, colour_type, interlace_type, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
if (colour_type == 3) /* palette */ { unsigned int i = 0; png_color pal[256];
do pal[i].red = pal[i].green = pal[i].blue = (png_byte)i; while(++i < 256U);
png_set_PLTE(pp, pi, pal, 256); }
png_write_info(pp, pi);
if (png_get_rowbytes(pp, pi) != transform_rowsize(pp, colour_type, bit_depth)) png_error(pp, "row size incorrect");
else { /* Somewhat confusingly this must be called *after* png_write_info
* because if it is called before, the information in *pp has not been * updated to reflect the interlaced image. */ int npasses = png_set_interlace_handling(pp); int pass;
if (npasses != npasses_from_interlace_type(pp, interlace_type)) png_error(pp, "write: png_set_interlace_handling failed");
for (pass=0; pass<npasses; ++pass) { png_uint_32 y;
for (y=0; y<h; ++y) { png_byte buffer[TRANSFORM_ROWMAX];
transform_row(pp, buffer, colour_type, bit_depth, y); png_write_row(pp, buffer); } } }
png_write_end(pp, pi);
/* And store this under the appropriate id, then clean up. */ store_storefile(ps, FILEID(colour_type, bit_depth, interlace_type, 0, 0, 0));
store_write_reset(ps); }
Catch(fault) { /* Use the png_store returned by the exception. This may help the compiler
* because 'ps' is not used in this branch of the setjmp. Note that fault * and ps will always be the same value. */ store_write_reset(fault); }}
static voidmake_standard(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type, int bdlo, int PNG_CONST bdhi){ for (; bdlo <= bdhi; ++bdlo) { int interlace_type;
for (interlace_type = PNG_INTERLACE_NONE; interlace_type < PNG_INTERLACE_LAST; ++interlace_type) { char name[FILE_NAME_SIZE];
standard_name(name, sizeof name, 0, colour_type, bdlo, interlace_type, 0, 0, 0); make_transform_image(ps, colour_type, DEPTH(bdlo), interlace_type, name); } }}
static voidmake_transform_images(png_store *ps){ /* This is in case of errors. */ safecat(ps->test, sizeof ps->test, 0, "make standard images");
/* Arguments are colour_type, low bit depth, high bit depth
*/ make_standard(ps, 0, 0, WRITE_BDHI); make_standard(ps, 2, 3, WRITE_BDHI); make_standard(ps, 3, 0, 3 /*palette: max 8 bits*/); make_standard(ps, 4, 3, WRITE_BDHI); make_standard(ps, 6, 3, WRITE_BDHI);}
/* The following two routines use the PNG interlace support macros from
* png.h to interlace or deinterlace rows. */static voidinterlace_row(png_bytep buffer, png_const_bytep imageRow, unsigned int pixel_size, png_uint_32 w, int pass){ png_uint_32 xin, xout, xstep;
/* Note that this can, trivially, be optimized to a memcpy on pass 7, the
* code is presented this way to make it easier to understand. In practice * consult the code in the libpng source to see other ways of doing this. */ xin = PNG_PASS_START_COL(pass); xstep = 1U<<PNG_PASS_COL_SHIFT(pass);
for (xout=0; xin<w; xin+=xstep) { pixel_copy(buffer, xout, imageRow, xin, pixel_size); ++xout; }}
static voiddeinterlace_row(png_bytep buffer, png_const_bytep row, unsigned int pixel_size, png_uint_32 w, int pass){ /* The inverse of the above, 'row' is part of row 'y' of the output image,
* in 'buffer'. The image is 'w' wide and this is pass 'pass', distribute * the pixels of row into buffer and return the number written (to allow * this to be checked). */ png_uint_32 xin, xout, xstep;
xout = PNG_PASS_START_COL(pass); xstep = 1U<<PNG_PASS_COL_SHIFT(pass);
for (xin=0; xout<w; xout+=xstep) { pixel_copy(buffer, xout, row, xin, pixel_size); ++xin; }}
/* Build a single row for the 'size' test images, this fills in only the
* first bit_width bits of the sample row. */static voidsize_row(png_byte buffer[SIZE_ROWMAX], png_uint_32 bit_width, png_uint_32 y){ /* height is in the range 1 to 16, so: */ y = ((y & 1) << 7) + ((y & 2) << 6) + ((y & 4) << 5) + ((y & 8) << 4); /* the following ensures bits are set in small images: */ y ^= 0xA5;
while (bit_width >= 8) *buffer++ = (png_byte)y++, bit_width -= 8;
/* There may be up to 7 remaining bits, these go in the most significant
* bits of the byte. */ if (bit_width > 0) { png_uint_32 mask = (1U<<(8-bit_width))-1; *buffer = (png_byte)((*buffer & mask) | (y & ~mask)); }}
static voidmake_size_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type, png_byte PNG_CONST bit_depth, int PNG_CONST interlace_type, png_uint_32 PNG_CONST w, png_uint_32 PNG_CONST h, int PNG_CONST do_interlace){ context(ps, fault);
Try { png_infop pi; png_structp pp; unsigned int pixel_size;
/* Make a name and get an appropriate id for the store: */ char name[FILE_NAME_SIZE]; PNG_CONST png_uint_32 id = FILEID(colour_type, bit_depth, interlace_type, w, h, do_interlace);
standard_name_from_id(name, sizeof name, 0, id); pp = set_store_for_write(ps, &pi, name);
/* In the event of a problem return control to the Catch statement below
* to do the clean up - it is not possible to 'return' directly from a Try * block. */ if (pp == NULL) Throw ps;
png_set_IHDR(pp, pi, w, h, bit_depth, colour_type, interlace_type, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
/* Same palette as make_transform_image - I don' think there is any
* benefit from using a different one (JB 20101211) */ if (colour_type == 3) /* palette */ { unsigned int i = 0; png_color pal[256];
do pal[i].red = pal[i].green = pal[i].blue = (png_byte)i; while(++i < 256U);
png_set_PLTE(pp, pi, pal, 256); }
png_write_info(pp, pi);
/* Calculate the bit size, divide by 8 to get the byte size - this won't
* overflow because we know the w values are all small enough even for * a system where 'unsigned int' is only 16 bits. */ pixel_size = bit_size(pp, colour_type, bit_depth); if (png_get_rowbytes(pp, pi) != ((w * pixel_size) + 7) / 8) png_error(pp, "row size incorrect");
else { int npasses = npasses_from_interlace_type(pp, interlace_type); png_uint_32 y; int pass; png_byte image[16][SIZE_ROWMAX];
/* To help consistent error detection make the parts of this buffer
* that aren't set below all '1': */ memset(image, 0xff, sizeof image);
if (!do_interlace && npasses != png_set_interlace_handling(pp)) png_error(pp, "write: png_set_interlace_handling failed");
/* Prepare the whole image first to avoid making it 7 times: */ for (y=0; y<h; ++y) size_row(image[y], w * pixel_size, y);
for (pass=0; pass<npasses; ++pass) { /* The following two are for checking the macros: */ PNG_CONST png_uint_32 wPass = PNG_PASS_COLS(w, pass);
/* If do_interlace is set we don't call png_write_row for every
* row because some of them are empty. In fact, for a 1x1 image, * most of them are empty! */ for (y=0; y<h; ++y) { png_const_bytep row = image[y]; png_byte tempRow[SIZE_ROWMAX];
/* If do_interlace *and* the image is interlaced we
* need a reduced interlace row, this may be reduced * to empty. */ if (do_interlace && interlace_type == PNG_INTERLACE_ADAM7) { /* The row must not be written if it doesn't exist, notice
* that there are two conditions here, either the row isn't * ever in the pass or the row would be but isn't wide * enough to contribute any pixels. In fact the wPass test * can be used to skip the whole y loop in this case. */ if (PNG_ROW_IN_INTERLACE_PASS(y, pass) && wPass > 0) { /* Set to all 1's for error detection (libpng tends to
* set unset things to 0). */ memset(tempRow, 0xff, sizeof tempRow); interlace_row(tempRow, row, pixel_size, w, pass); row = tempRow; } else continue; }
/* Only get to here if the row has some pixels in it. */ png_write_row(pp, row); } } }
png_write_end(pp, pi);
/* And store this under the appropriate id, then clean up. */ store_storefile(ps, id);
store_write_reset(ps); }
Catch(fault) { /* Use the png_store returned by the exception. This may help the compiler
* because 'ps' is not used in this branch of the setjmp. Note that fault * and ps will always be the same value. */ store_write_reset(fault); }}
static voidmake_size(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type, int bdlo, int PNG_CONST bdhi){ for (; bdlo <= bdhi; ++bdlo) { png_uint_32 width;
for (width = 1; width <= 16; ++width) { png_uint_32 height;
for (height = 1; height <= 16; ++height) { /* The four combinations of DIY interlace and interlace or not -
* no interlace + DIY should be identical to no interlace with * libpng doing it. */ make_size_image(ps, colour_type, DEPTH(bdlo), PNG_INTERLACE_NONE, width, height, 0); make_size_image(ps, colour_type, DEPTH(bdlo), PNG_INTERLACE_NONE, width, height, 1); make_size_image(ps, colour_type, DEPTH(bdlo), PNG_INTERLACE_ADAM7, width, height, 0); make_size_image(ps, colour_type, DEPTH(bdlo), PNG_INTERLACE_ADAM7, width, height, 1); } } }}
static voidmake_size_images(png_store *ps){ /* This is in case of errors. */ safecat(ps->test, sizeof ps->test, 0, "make size images");
/* Arguments are colour_type, low bit depth, high bit depth
*/ make_size(ps, 0, 0, WRITE_BDHI); make_size(ps, 2, 3, WRITE_BDHI); make_size(ps, 3, 0, 3 /*palette: max 8 bits*/); make_size(ps, 4, 3, WRITE_BDHI); make_size(ps, 6, 3, WRITE_BDHI);}
/* Return a row based on image id and 'y' for checking: */static voidstandard_row(png_structp pp, png_byte std[STANDARD_ROWMAX], png_uint_32 id, png_uint_32 y){ if (WIDTH_FROM_ID(id) == 0) transform_row(pp, std, COL_FROM_ID(id), DEPTH_FROM_ID(id), y); else size_row(std, WIDTH_FROM_ID(id) * bit_size(pp, COL_FROM_ID(id), DEPTH_FROM_ID(id)), y);}
/* Tests - individual test cases *//* Like 'make_standard' but errors are deliberately introduced into the calls
* to ensure that they get detected - it should not be possible to write an * invalid image with libpng! */static voidsBIT0_error_fn(png_structp pp, png_infop pi){ /* 0 is invalid... */ png_color_8 bad; bad.red = bad.green = bad.blue = bad.gray = bad.alpha = 0; png_set_sBIT(pp, pi, &bad);}
static voidsBIT_error_fn(png_structp pp, png_infop pi){ png_byte bit_depth; png_color_8 bad;
if (png_get_color_type(pp, pi) == PNG_COLOR_TYPE_PALETTE) bit_depth = 8;
else bit_depth = png_get_bit_depth(pp, pi);
/* Now we know the bit depth we can easily generate an invalid sBIT entry */ bad.red = bad.green = bad.blue = bad.gray = bad.alpha = (png_byte)(bit_depth+1); png_set_sBIT(pp, pi, &bad);}
static PNG_CONST struct{ void (*fn)(png_structp, png_infop); PNG_CONST char *msg; unsigned int warning :1; /* the error is a warning... */} error_test[] = { { sBIT0_error_fn, "sBIT(0): failed to detect error", 1 }, { sBIT_error_fn, "sBIT(too big): failed to detect error", 1 }, };
static voidmake_error(png_store* volatile ps, png_byte PNG_CONST colour_type, png_byte bit_depth, int interlace_type, int test, png_const_charp name){ context(ps, fault);
Try { png_structp pp; png_infop pi;
pp = set_store_for_write(ps, &pi, name);
if (pp == NULL) Throw ps;
png_set_IHDR(pp, pi, transform_width(pp, colour_type, bit_depth), transform_height(pp, colour_type, bit_depth), bit_depth, colour_type, interlace_type, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
if (colour_type == 3) /* palette */ { unsigned int i = 0; png_color pal[256];
do pal[i].red = pal[i].green = pal[i].blue = (png_byte)i; while(++i < 256U);
png_set_PLTE(pp, pi, pal, 256); }
/* Time for a few errors, these are in various optional chunks, the
* standard tests test the standard chunks pretty well. */# define exception__prev exception_prev_1
# define exception__env exception_env_1
Try { /* Expect this to throw: */ ps->expect_error = !error_test[test].warning; ps->expect_warning = error_test[test].warning; ps->saw_warning = 0; error_test[test].fn(pp, pi);
/* Normally the error is only detected here: */ png_write_info(pp, pi);
/* And handle the case where it was only a warning: */ if (ps->expect_warning && ps->saw_warning) Throw ps;
/* If we get here there is a problem, we have success - no error or
* no warning - when we shouldn't have success. Log an error. */ store_log(ps, pp, error_test[test].msg, 1 /*error*/); }
Catch (fault) ps = fault; /* expected exit, make sure ps is not clobbered */#undef exception__prev
#undef exception__env
/* And clear these flags */ ps->expect_error = 0; ps->expect_warning = 0;
/* Now write the whole image, just to make sure that the detected, or
* undetected, errro has not created problems inside libpng. */ if (png_get_rowbytes(pp, pi) != transform_rowsize(pp, colour_type, bit_depth)) png_error(pp, "row size incorrect");
else { png_uint_32 h = transform_height(pp, colour_type, bit_depth); int npasses = png_set_interlace_handling(pp); int pass;
if (npasses != npasses_from_interlace_type(pp, interlace_type)) png_error(pp, "write: png_set_interlace_handling failed");
for (pass=0; pass<npasses; ++pass) { png_uint_32 y;
for (y=0; y<h; ++y) { png_byte buffer[TRANSFORM_ROWMAX];
transform_row(pp, buffer, colour_type, bit_depth, y); png_write_row(pp, buffer); } } }
png_write_end(pp, pi);
/* The following deletes the file that was just written. */ store_write_reset(ps); }
Catch(fault) { store_write_reset(fault); }}
static intmake_errors(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type, int bdlo, int PNG_CONST bdhi){ for (; bdlo <= bdhi; ++bdlo) { int interlace_type;
for (interlace_type = PNG_INTERLACE_NONE; interlace_type < PNG_INTERLACE_LAST; ++interlace_type) { unsigned int test; char name[FILE_NAME_SIZE];
standard_name(name, sizeof name, 0, colour_type, bdlo, interlace_type, 0, 0, 0);
for (test=0; test<(sizeof error_test)/(sizeof error_test[0]); ++test) { make_error(&pm->this, colour_type, DEPTH(bdlo), interlace_type, test, name);
if (fail(pm)) return 0; } } }
return 1; /* keep going */}
static voidperform_error_test(png_modifier *pm){ /* Need to do this here because we just write in this test. */ safecat(pm->this.test, sizeof pm->this.test, 0, "error test");
if (!make_errors(pm, 0, 0, WRITE_BDHI)) return;
if (!make_errors(pm, 2, 3, WRITE_BDHI)) return;
if (!make_errors(pm, 3, 0, 3)) return;
if (!make_errors(pm, 4, 3, WRITE_BDHI)) return;
if (!make_errors(pm, 6, 3, WRITE_BDHI)) return;}
/* Because we want to use the same code in both the progressive reader and the
* sequential reader it is necessary to deal with the fact that the progressive * reader callbacks only have one parameter (png_get_progressive_ptr()), so this * must contain all the test parameters and all the local variables directly * accessible to the sequential reader implementation. * * The technique adopted is to reinvent part of what Dijkstra termed a * 'display'; an array of pointers to the stack frames of enclosing functions so * that a nested function definition can access the local (C auto) variables of * the functions that contain its definition. In fact C provides the first * pointer (the local variables - the stack frame pointer) and the last (the * global variables - the BCPL global vector typically implemented as global * addresses), this code requires one more pointer to make the display - the * local variables (and function call parameters) of the function that actually * invokes either the progressive or sequential reader. * * Perhaps confusingly this technique is confounded with classes - the * 'standard_display' defined here is sub-classed as the 'gamma_display' below. * A gamma_display is a standard_display, taking advantage of the ANSI-C * requirement that the pointer to the first member of a structure must be the * same as the pointer to the structure. This allows us to reuse standard_ * functions in the gamma test code; something that could not be done with * nested funtions! */typedef struct standard_palette_entry /* pngvalid format palette! */{ png_byte red; png_byte green; png_byte blue; png_byte alpha;} standard_palette[256];
typedef struct standard_display{ png_store* ps; /* Test parameters (passed to the function) */ png_byte colour_type; png_byte bit_depth; png_byte red_sBIT; /* Input data sBIT values. */ png_byte green_sBIT; png_byte blue_sBIT; png_byte alpha_sBIT; int interlace_type; png_uint_32 id; /* Calculated file ID */ png_uint_32 w; /* Width of image */ png_uint_32 h; /* Height of image */ int npasses; /* Number of interlaced passes */ png_uint_32 pixel_size; /* Width of one pixel in bits */ png_uint_32 bit_width; /* Width of output row in bits */ size_t cbRow; /* Bytes in a row of the output image */ int do_interlace; /* Do interlacing internally */ int is_transparent; /* Transparecy information was present. */ struct { png_uint_16 red; png_uint_16 green; png_uint_16 blue; } transparent; /* The transparent color, if set. */ standard_palette palette;} standard_display;
static voidstandard_display_init(standard_display *dp, png_store* ps, png_uint_32 id, int do_interlace){ dp->ps = ps; dp->colour_type = COL_FROM_ID(id); dp->bit_depth = DEPTH_FROM_ID(id); dp->alpha_sBIT = dp->blue_sBIT = dp->green_sBIT = dp->alpha_sBIT = dp->bit_depth; dp->interlace_type = INTERLACE_FROM_ID(id); dp->id = id; /* All the rest are filled in after the read_info: */ dp->w = 0; dp->h = 0; dp->npasses = 0; dp->pixel_size = 0; dp->bit_width = 0; dp->cbRow = 0; dp->do_interlace = do_interlace; dp->is_transparent = 0; /* Preset the transparent color to black: */ memset(&dp->transparent, 0, sizeof dp->transparent); /* Preset the palette to full intensity/opaque througout: */ memset(dp->palette, 0xff, sizeof dp->palette);
}
/* Call this only if the colour type is 3 - PNG_COLOR_TYPE_PALETTE - otherwise
* it will png_error out. The API returns true if tRNS information was * present. */static intstandard_palette_init(standard_palette palette, png_structp pp, png_infop pi){ png_colorp pal; png_bytep trans_alpha; int num;
pal = 0; num = -1; if (png_get_PLTE(pp, pi, &pal, &num) & PNG_INFO_PLTE) { int i;
for (i=0; i<num; ++i) { palette[i].red = pal[i].red; palette[i].green = pal[i].green; palette[i].blue = pal[i].blue; }
/* Mark the remainder of the entries with a flag value: */ for (; i<256; ++i) palette[i].red = palette[i].green = palette[i].blue = 126; }
else /* !png_get_PLTE */ png_error(pp, "validate: missing PLTE with color type 3");
trans_alpha = 0; num = -1; if (png_get_tRNS(pp, pi, &trans_alpha, &num, 0) & PNG_INFO_tRNS) { int i;
/* Any of these are crash-worthy - given the implementation of
* png_get_tRNS up to 1.5 an app won't crash if it just checks the * result above and fails to check that the variables it passed have * actually been filled in! Note that if the app were to pass the * last, png_color_16p, variable too it couldn't rely on this. */ if (trans_alpha == 0 || num <= 0 || num > 256) png_error(pp, "validate: unexpected png_get_tRNS (palette) result");
for (i=0; i<num; ++i) palette[i].alpha = trans_alpha[i];
for (; i<256; ++i) palette[i].alpha = 255;
return 1; /* transparency */ }
else { /* No transparency - just set the alpha channel to opaque. */ int i;
for (i=0; i<256; ++i) palette[i].alpha = 255;
return 0; /* no transparency */ }}
/* By passing a 'standard_display' the progressive callbacks can be used
* directly by the sequential code, the functions suffixed "_imp" are the * implementations, the functions without the suffix are the callbacks. * * The code for the info callback is split into two because this callback calls * png_read_update_info or png_start_read_image and what gets called depends on * whether the info needs updating (we want to test both calls in pngvalid.) */static voidstandard_info_part1(standard_display *dp, png_structp pp, png_infop pi){ if (png_get_bit_depth(pp, pi) != dp->bit_depth) png_error(pp, "validate: bit depth changed");
if (png_get_color_type(pp, pi) != dp->colour_type) png_error(pp, "validate: color type changed");
if (png_get_filter_type(pp, pi) != PNG_FILTER_TYPE_BASE) png_error(pp, "validate: filter type changed");
if (png_get_interlace_type(pp, pi) != dp->interlace_type) png_error(pp, "validate: interlacing changed");
if (png_get_compression_type(pp, pi) != PNG_COMPRESSION_TYPE_BASE) png_error(pp, "validate: compression type changed");
dp->w = png_get_image_width(pp, pi);
if (dp->w != standard_width(pp, dp->id)) png_error(pp, "validate: image width changed");
dp->h = png_get_image_height(pp, pi);
if (dp->h != standard_height(pp, dp->id)) png_error(pp, "validate: image height changed");
/* Record (but don't check at present) the input sBIT according to the colour
* type information. */ { png_color_8p sBIT = 0;
if (png_get_sBIT(pp, pi, &sBIT) & PNG_INFO_sBIT) { int sBIT_invalid = 0;
if (sBIT == 0) png_error(pp, "validate: unexpected png_get_sBIT result");
if (dp->colour_type & PNG_COLOR_MASK_COLOR) { if (sBIT->red == 0 || sBIT->red > dp->bit_depth) sBIT_invalid = 1; else dp->red_sBIT = sBIT->red;
if (sBIT->green == 0 || sBIT->green > dp->bit_depth) sBIT_invalid = 1; else dp->green_sBIT = sBIT->green;
if (sBIT->blue == 0 || sBIT->blue > dp->bit_depth) sBIT_invalid = 1; else dp->blue_sBIT = sBIT->blue; }
else /* !COLOR */ { if (sBIT->gray == 0 || sBIT->gray > dp->bit_depth) sBIT_invalid = 1; else dp->blue_sBIT = dp->green_sBIT = dp->red_sBIT = sBIT->gray; }
/* All 8 bits in tRNS for a palette image are significant - see the
* spec. */ if (dp->colour_type & PNG_COLOR_MASK_ALPHA) { if (sBIT->alpha == 0 || sBIT->alpha > dp->bit_depth) sBIT_invalid = 1; else dp->alpha_sBIT = sBIT->alpha; }
if (sBIT_invalid) png_error(pp, "validate: sBIT value out of range"); } }
/* Important: this is validating the value *before* any transforms have been
* put in place. It doesn't matter for the standard tests, where there are * no transforms, but it does for other tests where rowbytes may change after * png_read_update_info. */ if (png_get_rowbytes(pp, pi) != standard_rowsize(pp, dp->id)) png_error(pp, "validate: row size changed");
/* The palette is never read for non-palette images, even though it is valid
* - this could be changed. */ if (dp->colour_type == 3) /* palette */ { int i;
dp->is_transparent = standard_palette_init(dp->palette, pp, pi);
/* And validate the result. */ for (i=0; i<256; ++i) if (dp->palette[i].red != i || dp->palette[i].green != i || dp->palette[i].blue != i) png_error(pp, "validate: color type 3 PLTE chunk changed"); }
/* In any case always check for a tranparent color: */ { png_color_16p trans_color = 0;
if (png_get_tRNS(pp, pi, 0, 0, &trans_color) & PNG_INFO_tRNS) { if (trans_color == 0) png_error(pp, "validate: unexpected png_get_tRNS (color) result");
switch (dp->colour_type) { case 0: dp->transparent.red = dp->transparent.green = dp->transparent.blue = trans_color->gray; dp->is_transparent = 1; break;
case 2: dp->transparent.red = trans_color->red; dp->transparent.green = trans_color->green; dp->transparent.blue = trans_color->blue; dp->is_transparent = 1; break;
case 3: /* Not expected because it should result in the array case
* above. */ png_error(pp, "validate: unexpected png_get_tRNS result"); break;
default: png_error(pp, "validate: invalid tRNS chunk with alpha image"); } } }
/* Read the number of passes - expected to match the value used when
* creating the image (interlaced or not). This has the side effect of * turning on interlace handling (if do_interlace is not set.) */ dp->npasses = npasses_from_interlace_type(pp, dp->interlace_type); if (!dp->do_interlace && dp->npasses != png_set_interlace_handling(pp)) png_error(pp, "validate: file changed interlace type");
/* Caller calls png_read_update_info or png_start_read_image now, then calls
* part2. */}
/* This must be called *after* the png_read_update_info call to get the correct
* 'rowbytes' value, otherwise png_get_rowbytes will refer to the untransformed * image. */static voidstandard_info_part2(standard_display *dp, png_structp pp, png_infop pi, int nImages){ /* Record cbRow now that it can be found. */ dp->pixel_size = bit_size(pp, png_get_color_type(pp, pi), png_get_bit_depth(pp, pi)); dp->bit_width = png_get_image_width(pp, pi) * dp->pixel_size; dp->cbRow = png_get_rowbytes(pp, pi);
/* Validate the rowbytes here again. */ if (dp->cbRow != (dp->bit_width+7)/8) png_error(pp, "bad png_get_rowbytes calculation");
/* Then ensure there is enough space for the output image(s). */ store_ensure_image(dp->ps, pp, nImages * dp->cbRow * dp->h);}
static voidstandard_info_imp(standard_display *dp, png_structp pp, png_infop pi, int nImages){ /* Note that the validation routine has the side effect of turning on
* interlace handling in the subsequent code. */ standard_info_part1(dp, pp, pi);
/* And the info callback has to call this (or png_read_update_info - see
* below in the png_modifier code for that variant. */ png_start_read_image(pp);
/* Validate the height, width and rowbytes plus ensure that sufficient buffer
* exists for decoding the image. */ standard_info_part2(dp, pp, pi, nImages);}
static voidstandard_info(png_structp pp, png_infop pi){ standard_display *dp = png_get_progressive_ptr(pp);
/* Call with nImages==1 because the progressive reader can only produce one
* image. */ standard_info_imp(dp, pp, pi, 1 /*only one image*/);}
static voidprogressive_row(png_structp pp, png_bytep new_row, png_uint_32 y, int pass){ PNG_CONST standard_display *dp = png_get_progressive_ptr(pp);
/* When handling interlacing some rows will be absent in each pass, the
* callback still gets called, but with a NULL pointer. This is checked * in the 'else' clause below. We need our own 'cbRow', but we can't call * png_get_rowbytes because we got no info structure. */ if (new_row != NULL) { png_bytep row;
/* In the case where the reader doesn't do the interlace it gives
* us the y in the sub-image: */ if (dp->do_interlace && dp->interlace_type == PNG_INTERLACE_ADAM7) { /* Use this opportunity to validate the png 'current' APIs: */ if (y != png_get_current_row_number(pp)) png_error(pp, "png_get_current_row_number is broken");
if (pass != png_get_current_pass_number(pp)) png_error(pp, "png_get_current_pass_number is broken");
y = PNG_ROW_FROM_PASS_ROW(y, pass); }
/* Validate this just in case. */ if (y >= dp->h) png_error(pp, "invalid y to progressive row callback");
row = dp->ps->image + y * dp->cbRow;
/* Combine the new row into the old: */ if (dp->do_interlace) { if (dp->interlace_type == PNG_INTERLACE_ADAM7) deinterlace_row(row, new_row, dp->pixel_size, dp->w, pass); else memcpy(row, new_row, dp->cbRow); } else png_progressive_combine_row(pp, row, new_row); } else if (dp->interlace_type == PNG_INTERLACE_ADAM7 && PNG_ROW_IN_INTERLACE_PASS(y, pass) && PNG_PASS_COLS(dp->w, pass) > 0) png_error(pp, "missing row in progressive de-interlacing");}
static voidsequential_row(standard_display *dp, png_structp pp, png_infop pi, PNG_CONST png_bytep pImage, PNG_CONST png_bytep pDisplay){ PNG_CONST int npasses = dp->npasses; PNG_CONST int do_interlace = dp->do_interlace && dp->interlace_type == PNG_INTERLACE_ADAM7; PNG_CONST png_uint_32 height = standard_height(pp, dp->id); PNG_CONST png_uint_32 width = standard_width(pp, dp->id); PNG_CONST size_t cbRow = dp->cbRow; int pass;
for (pass=0; pass<npasses; ++pass) { png_uint_32 y; png_uint_32 wPass = PNG_PASS_COLS(width, pass); png_bytep pRow1 = pImage; png_bytep pRow2 = pDisplay;
for (y=0; y<height; ++y) { if (do_interlace) { /* wPass may be zero or this row may not be in this pass.
* png_read_row must not be called in either case. */ if (wPass > 0 && PNG_ROW_IN_INTERLACE_PASS(y, pass)) { /* Read the row into a pair of temporary buffers, then do the
* merge here into the output rows. */ png_byte row[STANDARD_ROWMAX], display[STANDARD_ROWMAX];
/* The following aids (to some extent) error detection - we can
* see where png_read_row wrote. Use opposite values in row and * display to make this easier. */ memset(row, 0xff, sizeof row); memset(display, 0, sizeof display);
png_read_row(pp, row, display);
if (pRow1 != NULL) deinterlace_row(pRow1, row, dp->pixel_size, dp->w, pass);
if (pRow2 != NULL) deinterlace_row(pRow2, display, dp->pixel_size, dp->w, pass); } } else png_read_row(pp, pRow1, pRow2);
if (pRow1 != NULL) pRow1 += cbRow;
if (pRow2 != NULL) pRow2 += cbRow; } }
/* And finish the read operation (only really necessary if the caller wants
* to find additional data in png_info from chunks after the last IDAT.) */ png_read_end(pp, pi);}
static voidstandard_row_validate(standard_display *dp, png_structp pp, png_const_bytep row, png_const_bytep display, png_uint_32 y){ png_byte std[STANDARD_ROWMAX];
memset(std, 0xff, sizeof std); standard_row(pp, std, dp->id, y);
/* At the end both the 'row' and 'display' arrays should end up identical.
* In earlier passes 'row' will be partially filled in, with only the pixels * that have been read so far, but 'display' will have those pixels * replicated to fill the unread pixels while reading an interlaced image. * The side effect inside the libpng sequential reader is that the 'row' * array retains the correct values for unwritten pixels within the row * bytes, while the 'display' array gets bits off the end of the image (in * the last byte) trashed. Unfortunately in the progressive reader the * row bytes are always trashed, so we always do a pixel_cmp here even though * a memcmp of all cbRow bytes will succeed for the sequential reader. */ if (row != NULL && pixel_cmp(std, row, dp->bit_width) != 0) { char msg[64]; sprintf(msg, "PNG image row %d changed", y); png_error(pp, msg); }
/* In this case use pixel_cmp because we need to compare a partial
* byte at the end of the row if the row is not an exact multiple * of 8 bits wide. */ if (display != NULL && pixel_cmp(std, display, dp->bit_width) != 0) { char msg[64]; sprintf(msg, "display row %d changed", y); png_error(pp, msg); }}
static voidstandard_image_validate(standard_display *dp, png_structp pp, png_const_bytep pImage, png_const_bytep pDisplay){ png_uint_32 y;
for (y=0; y<dp->h; ++y) { standard_row_validate(dp, pp, pImage, pDisplay, y);
if (pImage != NULL) pImage += dp->cbRow;
if (pDisplay != NULL) pDisplay += dp->cbRow; }
/* This avoids false positives if the validation code is never called! */ dp->ps->validated = 1;}
static voidstandard_end(png_structp pp, png_infop pi){ standard_display *dp = png_get_progressive_ptr(pp);
UNUSED(pi)
/* Validate the image - progressive reading only produces one variant for
* interlaced images. */ standard_image_validate(dp, pp, dp->ps->image, NULL);}
/* A single test run checking the standard image to ensure it is not damaged. */static voidstandard_test(png_store* PNG_CONST psIn, png_uint_32 PNG_CONST id, int do_interlace){ standard_display d; context(psIn, fault);
/* Set up the display (stack frame) variables from the arguments to the
* function and initialize the locals that are filled in later. */ standard_display_init(&d, psIn, id, do_interlace);
/* Everything is protected by a Try/Catch. The functions called also
* typically have local Try/Catch blocks. */ Try { png_structp pp; png_infop pi;
/* Get a png_struct for reading the image. This will throw an error if it
* fails, so we don't need to check the result. */ pp = set_store_for_read(d.ps, &pi, d.id, d.do_interlace ? (d.ps->progressive ? "pngvalid progressive deinterlacer" : "pngvalid sequential deinterlacer") : (d.ps->progressive ? "progressive reader" : "sequential reader"));
/* Introduce the correct read function. */ if (d.ps->progressive) { png_set_progressive_read_fn(pp, &d, standard_info, progressive_row, standard_end);
/* Now feed data into the reader until we reach the end: */ store_progressive_read(d.ps, pp, pi); } else { /* Note that this takes the store, not the display. */ png_set_read_fn(pp, d.ps, store_read);
/* Check the header values: */ png_read_info(pp, pi);
/* The code tests both versions of the images that the sequential
* reader can produce. */ standard_info_imp(&d, pp, pi, 2 /*images*/);
/* Need the total bytes in the image below; we can't get to this point
* unless the PNG file values have been checked against the expected * values. */ { PNG_CONST png_bytep pImage = d.ps->image; PNG_CONST png_bytep pDisplay = pImage + d.cbRow * d.h;
sequential_row(&d, pp, pi, pImage, pDisplay);
/* After the last pass loop over the rows again to check that the
* image is correct. */ standard_image_validate(&d, pp, pImage, pDisplay); } }
/* Check for validation. */ if (!d.ps->validated) png_error(pp, "image read failed silently");
/* Successful completion. */ }
Catch(fault) d.ps = fault; /* make sure this hasn't been clobbered. */
/* In either case clean up the store. */ store_read_reset(d.ps);}
static inttest_standard(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type, int bdlo, int PNG_CONST bdhi){ for (; bdlo <= bdhi; ++bdlo) { int interlace_type;
for (interlace_type = PNG_INTERLACE_NONE; interlace_type < PNG_INTERLACE_LAST; ++interlace_type) { standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), interlace_type, 0, 0, 0), 0/*do_interlace*/);
if (fail(pm)) return 0; } }
return 1; /* keep going */}
static voidperform_standard_test(png_modifier *pm){ /* Test each colour type over the valid range of bit depths (expressed as
* log2(bit_depth) in turn, stop as soon as any error is detected. */ if (!test_standard(pm, 0, 0, READ_BDHI)) return;
if (!test_standard(pm, 2, 3, READ_BDHI)) return;
if (!test_standard(pm, 3, 0, 3)) return;
if (!test_standard(pm, 4, 3, READ_BDHI)) return;
if (!test_standard(pm, 6, 3, READ_BDHI)) return;}
/********************************** SIZE TESTS ********************************/static inttest_size(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type, int bdlo, int PNG_CONST bdhi){ /* Run the tests on each combination.
* * NOTE: on my 32 bit x86 each of the following blocks takes * a total of 3.5 seconds if done across every combo of bit depth * width and height. This is a waste of time in practice, hence the * hinc and winc stuff: */ static PNG_CONST png_byte hinc[] = {1, 3, 11, 1, 5}; static PNG_CONST png_byte winc[] = {1, 9, 5, 7, 1}; for (; bdlo <= bdhi; ++bdlo) { png_uint_32 h, w;
for (h=1; h<=16; h+=hinc[bdlo]) for (w=1; w<=16; w+=winc[bdlo]) { /* First test all the 'size' images against the sequential
* reader using libpng to deinterlace (where required.) This * validates the write side of libpng. There are four possibilities * to validate. */ standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), PNG_INTERLACE_NONE, w, h, 0), 0/*do_interlace*/);
if (fail(pm)) return 0;
standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), PNG_INTERLACE_NONE, w, h, 1), 0/*do_interlace*/);
if (fail(pm)) return 0;
standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), PNG_INTERLACE_ADAM7, w, h, 0), 0/*do_interlace*/);
if (fail(pm)) return 0;
standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), PNG_INTERLACE_ADAM7, w, h, 1), 0/*do_interlace*/);
if (fail(pm)) return 0;
/* Now validate the interlaced read side - do_interlace true,
* in the progressive case this does actually make a difference * to the code used in the non-interlaced case too. */ standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), PNG_INTERLACE_NONE, w, h, 0), 1/*do_interlace*/);
if (fail(pm)) return 0;
standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), PNG_INTERLACE_ADAM7, w, h, 0), 1/*do_interlace*/);
if (fail(pm)) return 0; } }
return 1; /* keep going */}
static voidperform_size_test(png_modifier *pm){ /* Test each colour type over the valid range of bit depths (expressed as
* log2(bit_depth) in turn, stop as soon as any error is detected. */ if (!test_size(pm, 0, 0, READ_BDHI)) return;
if (!test_size(pm, 2, 3, READ_BDHI)) return;
/* For the moment don't do the palette test - it's a waste of time when
* compared to the greyscale test. */#if 0
if (!test_size(pm, 3, 0, 3)) return;#endif
if (!test_size(pm, 4, 3, READ_BDHI)) return;
if (!test_size(pm, 6, 3, READ_BDHI)) return;}
/******************************* TRANSFORM TESTS ******************************//* A set of tests to validate libpng image transforms. The possibilities here
* are legion because the transforms can be combined in a combinatorial * fashion. To deal with this some measure of restraint is required, otherwise * the tests would take forever. */typedef struct image_pixel{ /* A local (pngvalid) representation of a PNG pixel, in all its
* various forms. */ unsigned int red, green, blue, alpha; /* For non-palette images. */ unsigned int palette_index; /* For a palette image. */ png_byte colour_type; /* As in the spec. */ png_byte bit_depth; /* Defines bit size in row */ png_byte sample_depth; /* Scale of samples */ int have_tRNS; /* tRNS chunk may need processing */
/* For checking the code calculates double precision floating point values
* along with an error value, accumulated from the transforms. Because an * sBIT setting allows larger error bounds (indeed, by the spec, apparently * up to just less than +/-1 in the scaled value) the *lowest* sBIT for each * channel is stored. This sBIT value is folded in to the stored error value * at the end of the application of the transforms to the pixel. */ double redf, greenf, bluef, alphaf; double rede, greene, bluee, alphae; png_byte red_sBIT, green_sBIT, blue_sBIT, alpha_sBIT;} image_pixel;
/* Shared utility function, see below. */static voidimage_pixel_setf(image_pixel *this, unsigned int max){ this->redf = this->red / (double)max; this->greenf = this->green / (double)max; this->bluef = this->blue / (double)max; this->alphaf = this->alpha / (double)max;
if (this->red < max) this->rede = this->redf * DBL_EPSILON; else this->rede = 0; if (this->green < max) this->greene = this->greenf * DBL_EPSILON; else this->greene = 0; if (this->blue < max) this->bluee = this->bluef * DBL_EPSILON; else this->bluee = 0; if (this->alpha < max) this->alphae = this->alphaf * DBL_EPSILON; else this->alphae = 0;}
/* Initialize the structure for the next pixel - call this before doing any
* transforms and call it for each pixel since all the fields may need to be * reset. */static voidimage_pixel_init(image_pixel *this, png_const_bytep row, png_byte colour_type, png_byte bit_depth, png_uint_32 x, standard_palette palette){ PNG_CONST png_byte sample_depth = (png_byte)(colour_type == PNG_COLOR_TYPE_PALETTE ? 8 : bit_depth); PNG_CONST unsigned int max = (1U<<sample_depth)-1;
/* Initially just set everything to the same number and the alpha to opaque.
* Note that this currently assumes a simple palette where entry x has colour * rgb(x,x,x)! */ this->palette_index = this->red = this->green = this->blue = sample(row, colour_type, bit_depth, x, 0); this->alpha = max; this->red_sBIT = this->green_sBIT = this->blue_sBIT = this->alpha_sBIT = sample_depth;
/* Then override as appropriate: */ if (colour_type == 3) /* palette */ { /* This permits the caller to default to the sample value. */ if (palette != 0) { PNG_CONST unsigned int i = this->palette_index;
this->red = palette[i].red; this->green = palette[i].green; this->blue = palette[i].blue; this->alpha = palette[i].alpha; } }
else /* not palette */ { unsigned int i = 0;
if (colour_type & 2) { this->green = sample(row, colour_type, bit_depth, x, 1); this->blue = sample(row, colour_type, bit_depth, x, 2); i = 2; } if (colour_type & 4) this->alpha = sample(row, colour_type, bit_depth, x, ++i); }
/* Calculate the scaled values, these are simply the values divided by
* 'max' and the error is initialized to the double precision epsilon value * from the header file. */ image_pixel_setf(this, max);
/* Store the input information for use in the transforms - these will
* modify the information. */ this->colour_type = colour_type; this->bit_depth = bit_depth; this->sample_depth = sample_depth; this->have_tRNS = 0;}
/* Convert a palette image to an rgb image. This necessarily converts the tRNS
* chunk at the same time, because the tRNS will be in palette form. */static voidimage_pixel_convert_PLTE(image_pixel *this, const standard_display *display){ if (this->colour_type == PNG_COLOR_TYPE_PALETTE) { PNG_CONST unsigned int i = this->palette_index;
this->bit_depth = this->sample_depth; this->red = display->palette[i].red; this->green = display->palette[i].green; this->blue = display->palette[i].blue; this->red_sBIT = display->red_sBIT; this->green_sBIT = display->green_sBIT; this->blue_sBIT = display->blue_sBIT;
if (this->have_tRNS) { this->alpha = display->palette[i].alpha; this->colour_type = PNG_COLOR_TYPE_RGB_ALPHA; this->have_tRNS = 0; } else { this->alpha = 255; this->colour_type = PNG_COLOR_TYPE_RGB; } this->alpha_sBIT = 8;
/* And regenerate the scaled values and all the errors, which are now set
* back to the initial values. */ image_pixel_setf(this, 255); }}
/* Add an alpha channel, this will glom in the tRNS information because tRNS is
* not valid in an alpha image. The bit depth will invariably be set to at * least 8. Palette images will be converted to alpha (using the above API). */static voidimage_pixel_add_alpha(image_pixel *this, const standard_display *display){ if (this->colour_type == PNG_COLOR_TYPE_PALETTE) image_pixel_convert_PLTE(this, display);
if ((this->colour_type & PNG_COLOR_MASK_ALPHA) == 0) { if (this->colour_type == PNG_COLOR_TYPE_GRAY) { if (this->bit_depth < 8) this->bit_depth = 8;
if (this->have_tRNS) { this->have_tRNS = 0;
/* Check the input, original, channel value here against the
* original tRNS gray chunk valie. */ if (this->red == display->transparent.red) this->alphaf = 0; else this->alphaf = 1; } else this->alphaf = 1;
this->colour_type = PNG_COLOR_TYPE_GRAY_ALPHA; }
else if (this->colour_type == PNG_COLOR_TYPE_RGB) { if (this->have_tRNS) { this->have_tRNS = 0;
/* Again, check the exact input values, not the current transformed
* value! */ if (this->red == display->transparent.red && this->green == display->transparent.green && this->blue == display->transparent.blue) this->alphaf = 0; else this->alphaf = 1;
this->colour_type = PNG_COLOR_TYPE_RGB_ALPHA; } }
/* The error in the alpha is zero and the sBIT value comes from the
* original sBIT data (actually it will always be the original bit depth). */ this->alphae = 0; this->alpha_sBIT = display->alpha_sBIT; }}
struct transform_display;typedef struct image_transform{ /* The name of this transform: a string. */ PNG_CONST char *name;
/* Each transform can be disabled from the command line: */ int enable;
/* The global list of transforms; read only. */ struct image_transform *PNG_CONST list;
/* The global count of the number of times this transform has been set on an
* image. */ unsigned int global_use;
/* The local count of the number of times this transform has been set. */ unsigned int local_use;
/* The next transform in the list, each transform must call its own next
* transform after it has processed the pixel successfully. */ PNG_CONST struct image_transform *next;
/* A single transform for the image, expressed as a series of function
* callbacks and some space for values. * * First a callback to set the transform on the current png_read_struct: */ void (*set)(PNG_CONST struct image_transform *this, struct transform_display *that, png_structp pp, png_infop pi);
/* Then a transform that takes an input pixel in one PNG format or another
* and modifies it by a pngvalid implementation of the transform (thus * duplicating the libpng intent without, we hope, duplicating the bugs * in the libpng implementation!) The png_structp is solely to allow error * reporting via png_error and png_warning. */ void (*mod)(PNG_CONST struct image_transform *this, image_pixel *that, png_structp pp, PNG_CONST struct transform_display *display);
/* Add this transform to the list and return true if the transform is
* meaningful for this colour type and bit depth - if false then the * transform should have no effect on the image so there's not a lot of * point running it. */ int (*add)(struct image_transform *this, PNG_CONST struct image_transform **that, png_byte colour_type, png_byte bit_depth);} image_transform;
typedef struct transform_display{ standard_display this;
/* Parameters */ png_modifier* pm; PNG_CONST image_transform* transform_list;
/* Local variables */ png_byte output_colour_type; png_byte output_bit_depth;} transform_display;
/* Two functions to end the list: */static voidimage_transform_set_end(PNG_CONST image_transform *this, transform_display *that, png_structp pp, png_infop pi){ UNUSED(this) UNUSED(that) UNUSED(pp) UNUSED(pi)}
/* At the end of the list recalculate the output image pixel value from the
* double precision values set up by the preceding 'mod' calls: */static unsigned intsample_scale(double sample_value, unsigned int scale){ sample_value = floor(sample_value * scale + .5);
/* Return NaN as 0: */ if (!(sample_value > 0)) sample_value = 0; else if (sample_value > scale) sample_value = scale;
return (unsigned int)sample_value;}
static voidimage_transform_mod_end(PNG_CONST image_transform *this, image_pixel *that, png_structp pp, PNG_CONST transform_display *display){ PNG_CONST unsigned int scale = (1U<<that->sample_depth)-1;
UNUSED(this) UNUSED(pp) UNUSED(display)
/* At the end recalculate the digitized red green and blue values according
* to the current sample_depth of the pixel. * * The sample value is simply scaled to the maximum, checking for over * and underflow (which can both happen for some image transforms, * including simple size scaling, though libpng doesn't do that at present. */ that->red = sample_scale(that->redf, scale);
/* The error value is increased, at the end, according to the lowest sBIT
* value seen. Common sense tells us that the intermediate integer * representations are no more accurate than +/- 0.5 in the integral values, * the sBIT allows the implementation to be worse than this. In addition the * PNG specification actually permits any error within the range (-1..+1), * but that is ignored here. Instead the final digitized value is compared, * below to the digitized value of the error limits - this has the net effect * of allowing (almost) +/-1 in the output value. It's difficult to see how * any algorithm that digitizes intermediate results can be more accurate. */ that->rede += 1./(2*((1U<<that->red_sBIT)-1));
if (that->colour_type & PNG_COLOR_MASK_COLOR) { that->green = sample_scale(that->greenf, scale); that->blue = sample_scale(that->bluef, scale); that->greene += 1./(2*((1U<<that->green_sBIT)-1)); that->bluee += 1./(2*((1U<<that->blue_sBIT)-1)); } else { that->blue = that->green = that->red; that->bluef = that->greenf = that->redf; that->bluee = that->greene = that->rede; }
if ((that->colour_type & PNG_COLOR_MASK_ALPHA) || that->colour_type == PNG_COLOR_TYPE_PALETTE) { that->alpha = sample_scale(that->alphaf, scale); that->alphae += 1./(2*((1U<<that->alpha_sBIT)-1)); } else { that->alpha = scale; /* opaque */ that->alpha = 1; /* Override this. */ that->alphae = 0; /* It's exact ;-) */ }}
/* Static 'end' structure: */static image_transform image_transform_end ={ "(end)", /* name */ 1, /* enable */ 0, /* list */ 0, /* global_use */ 0, /* local_use */ 0, /* next */ image_transform_set_end, image_transform_mod_end, 0 /* never called, I want it to crash if it is! */};
/* Reader callbacks and implementations, where they differ from the standard
* ones. */static voidtransform_display_init(transform_display *dp, png_modifier *pm, png_uint_32 id, PNG_CONST image_transform *transform_list){ /* Standard fields */ standard_display_init(&dp->this, &pm->this, id, 0/*do_interlace*/);
/* Parameter fields */ dp->pm = pm; dp->transform_list = transform_list;
/* Local variable fields */ dp->output_colour_type = 255; /* invalid */ dp->output_bit_depth = 255; /* invalid */}
static voidtransform_info_imp(transform_display *dp, png_structp pp, png_infop pi){ /* Reuse the standard stuff as appropriate. */ standard_info_part1(&dp->this, pp, pi);
/* Now set the list of transforms. */ dp->transform_list->set(dp->transform_list, dp, pp, pi);
/* Update the info structure for these transforms: */ png_read_update_info(pp, pi);
/* And get the output information into the standard_display */ standard_info_part2(&dp->this, pp, pi, 1/*images*/);
/* Plus the extra stuff we need for the transform tests: */ dp->output_colour_type = png_get_color_type(pp, pi); dp->output_bit_depth = png_get_bit_depth(pp, pi);
/* Validate the combination of colour type and bit depth that we are getting
* out of libpng; the semantics of something not in the PNG spec are, at * best, unclear. */ switch (dp->output_colour_type) { case PNG_COLOR_TYPE_PALETTE: if (dp->output_bit_depth > 8) goto error; /*FALL THROUGH*/ case PNG_COLOR_TYPE_GRAY: if (dp->output_bit_depth == 1 || dp->output_bit_depth == 2 || dp->output_bit_depth == 4) break; /*FALL THROUGH*/ default: if (dp->output_bit_depth == 8 || dp->output_bit_depth == 16) break; /*FALL THROUGH*/ error: { char message[128]; size_t pos;
pos = safecat(message, sizeof message, 0, "invalid final bit depth: colour type("); pos = safecatn(message, sizeof message, pos, dp->output_colour_type); pos = safecat(message, sizeof message, pos, ") with bit depth: "); pos = safecatn(message, sizeof message, pos, dp->output_bit_depth);
png_error(pp, message); } }
/* Use a test pixel to check that the output agrees with what we expect -
* this avoids running the whole test if the output is unexpected. */ { image_pixel test_pixel;
memset(&test_pixel, 0, sizeof test_pixel); test_pixel.colour_type = dp->this.colour_type; /* input */ test_pixel.bit_depth = dp->this.bit_depth; if (test_pixel.colour_type == PNG_COLOR_TYPE_PALETTE) test_pixel.sample_depth = 8; else test_pixel.sample_depth = test_pixel.bit_depth; /* Don't need sBIT here */ test_pixel.have_tRNS = dp->this.is_transparent;
dp->transform_list->mod(dp->transform_list, &test_pixel, pp, dp);
if (test_pixel.colour_type != dp->output_colour_type) { char message[128]; size_t pos = safecat(message, sizeof message, 0, "colour type ");
pos = safecatn(message, sizeof message, pos, dp->output_colour_type); pos = safecat(message, sizeof message, pos, " expected "); pos = safecatn(message, sizeof message, pos, test_pixel.colour_type);
png_error(pp, message); }
if (test_pixel.bit_depth != dp->output_bit_depth) { char message[128]; size_t pos = safecat(message, sizeof message, 0, "bit depth ");
pos = safecatn(message, sizeof message, pos, dp->output_bit_depth); pos = safecat(message, sizeof message, pos, " expected "); pos = safecatn(message, sizeof message, pos, test_pixel.bit_depth);
png_error(pp, message); }
/* If both bit depth and colour type are correct check the sample depth.
* I believe these are both internal errors. */ if (test_pixel.colour_type == PNG_COLOR_TYPE_PALETTE) { if (test_pixel.sample_depth != 8) /* oops - internal error! */ png_error(pp, "pngvalid: internal: palette sample depth not 8"); } else if (test_pixel.sample_depth != dp->output_bit_depth) { char message[128]; size_t pos = safecat(message, sizeof message, 0, "internal: sample depth ");
pos = safecatn(message, sizeof message, pos, dp->output_bit_depth); pos = safecat(message, sizeof message, pos, " expected "); pos = safecatn(message, sizeof message, pos, test_pixel.sample_depth);
png_error(pp, message); } }}
static voidtransform_info(png_structp pp, png_infop pi){ transform_info_imp(png_get_progressive_ptr(pp), pp, pi);}
static voidtransform_range_check(png_structp pp, unsigned int r, unsigned int g, unsigned int b, unsigned int a, unsigned int in_digitized, double in, unsigned int out, png_byte sample_depth, double err, PNG_CONST char *name){ /* Compare the scaled, digitzed, values of our local calculation (in+-err)
* with the digitized values libpng produced; 'sample_depth' is the actual * digitization depth of the libpng output colors (the bit depth except for * palette images where it is always 8.) */ unsigned int max = (1U<<sample_depth)-1; double in_min = ceil((in-err)*max - .5); double in_max = floor((in+err)*max + .5); if (!(out >= in_min && out <= in_max)) { char message[256]; size_t pos;
pos = safecat(message, sizeof message, 0, name); pos = safecat(message, sizeof message, pos, " output value error: rgba("); pos = safecatn(message, sizeof message, pos, r); pos = safecat(message, sizeof message, pos, ","); pos = safecatn(message, sizeof message, pos, g); pos = safecat(message, sizeof message, pos, ","); pos = safecatn(message, sizeof message, pos, b); pos = safecat(message, sizeof message, pos, ","); pos = safecatn(message, sizeof message, pos, a); pos = safecat(message, sizeof message, pos, "): "); pos = safecatn(message, sizeof message, pos, out); pos = safecat(message, sizeof message, pos, " expected: "); pos = safecatn(message, sizeof message, pos, in_digitized); pos = safecat(message, sizeof message, pos, " ("); pos = safecatd(message, sizeof message, pos, (in-err)*max, 3); pos = safecat(message, sizeof message, pos, ".."); pos = safecatd(message, sizeof message, pos, (in+err)*max, 3); pos = safecat(message, sizeof message, pos, ")");
png_error(pp, message); }}
static voidtransform_image_validate(transform_display *dp, png_structp pp, png_infop pi, png_const_bytep pRow){ /* Constants for the loop below: */ PNG_CONST png_byte in_ct = dp->this.colour_type; PNG_CONST png_byte in_bd = dp->this.bit_depth; PNG_CONST png_uint_32 w = dp->this.w; PNG_CONST png_uint_32 h = dp->this.h; PNG_CONST size_t cbRow = dp->this.cbRow; PNG_CONST png_byte out_ct = dp->output_colour_type; PNG_CONST png_byte out_bd = dp->output_bit_depth; PNG_CONST png_byte sample_depth = (png_byte)(out_ct == PNG_COLOR_TYPE_PALETTE ? 8 : out_bd); PNG_CONST png_byte red_sBIT = dp->this.red_sBIT; PNG_CONST png_byte green_sBIT = dp->this.green_sBIT; PNG_CONST png_byte blue_sBIT = dp->this.blue_sBIT; PNG_CONST png_byte alpha_sBIT = dp->this.alpha_sBIT; PNG_CONST int have_tRNS = dp->this.is_transparent;
standard_palette out_palette; png_uint_32 y;
UNUSED(pi)
/* Read the palette corresponding to the output if the output colour type
* indicates a palette, othewise set out_palette to garbage. */ if (out_ct == PNG_COLOR_TYPE_PALETTE) (void)standard_palette_init(out_palette, pp, pi); else memset(out_palette, 0x5e, sizeof out_palette);
for (y=0; y<h; ++y, pRow += cbRow) { png_uint_32 x;
/* The original, standard, row pre-transforms. */ png_byte std[STANDARD_ROWMAX];
transform_row(pp, std, in_ct, in_bd, y);
/* Go through each original pixel transforming it and comparing with what
* libpng did to the same pixel. */ for (x=0; x<w; ++x) { image_pixel in_pixel, out_pixel; unsigned int r, g, b, a;
/* Find out what we think the pixel should be: */ image_pixel_init(&in_pixel, std, in_ct, in_bd, x, dp->this.palette);
in_pixel.red_sBIT = red_sBIT; in_pixel.green_sBIT = green_sBIT; in_pixel.blue_sBIT = blue_sBIT; in_pixel.alpha_sBIT = alpha_sBIT; in_pixel.have_tRNS = have_tRNS;
/* For error detection, below. */ r = in_pixel.red; g = in_pixel.green; b = in_pixel.blue; a = in_pixel.alpha;
dp->transform_list->mod(dp->transform_list, &in_pixel, pp, dp);
/* Read the output pixel and compare it to what we got, we don't
* use the error field here, so no need to update sBIT. */ image_pixel_init(&out_pixel, pRow, out_ct, out_bd, x, out_palette);
/* We don't expect changes to the index here even if the bit depth is
* changed. */ if (in_ct == PNG_COLOR_TYPE_PALETTE && out_ct == PNG_COLOR_TYPE_PALETTE) { if (in_pixel.palette_index != out_pixel.palette_index) png_error(pp, "unexpected transformed palette index"); }
/* Check the colours for palette images too - in fact the palette could
* be separately verified itself in most cases. */ if (in_pixel.red != out_pixel.red) transform_range_check(pp, r, g, b, a, in_pixel.red, in_pixel.redf, out_pixel.red, sample_depth, in_pixel.rede, "red/gray");
if ((out_ct & PNG_COLOR_MASK_COLOR) != 0 && in_pixel.green != out_pixel.green) transform_range_check(pp, r, g, b, a, in_pixel.green, in_pixel.greenf, out_pixel.green, sample_depth, in_pixel.greene, "green");
if ((out_ct & PNG_COLOR_MASK_COLOR) != 0 && in_pixel.blue != out_pixel.blue) transform_range_check(pp, r, g, b, a, in_pixel.blue, in_pixel.bluef, out_pixel.blue, sample_depth, in_pixel.bluee, "blue");
if ((out_ct & PNG_COLOR_MASK_ALPHA) != 0 && in_pixel.alpha != out_pixel.alpha) transform_range_check(pp, r, g, b, a, in_pixel.alpha, in_pixel.alphaf, out_pixel.alpha, sample_depth, in_pixel.alphae, "alpha"); } /* pixel (x) loop */ } /* row (y) loop */
/* Record that something was actually checked to avoid a false positive. */ dp->this.ps->validated = 1;}
static voidtransform_end(png_structp pp, png_infop pi){ transform_display *dp = png_get_progressive_ptr(pp);
transform_image_validate(dp, pp, pi, dp->this.ps->image);}
/* A single test run. */static voidtransform_test(png_modifier *pmIn, PNG_CONST png_uint_32 idIn, PNG_CONST image_transform* transform_listIn, PNG_CONST char *name){ transform_display d; context(&pmIn->this, fault);
transform_display_init(&d, pmIn, idIn, transform_listIn);
Try { png_structp pp; png_infop pi;
/* Get a png_struct for writing the image. */ pp = set_modifier_for_read(d.pm, &pi, d.this.id, name);
# if 0
/* Logging (debugging only) */ { char buffer[256];
(void)store_message(&d.pm->this, pp, buffer, sizeof buffer, 0, "running test");
fprintf(stderr, "%s\n", buffer); }# endif
/* Introduce the correct read function. */ if (d.pm->this.progressive) { /* Share the row function with the standard implementation. */ png_set_progressive_read_fn(pp, &d, transform_info, progressive_row, transform_end);
/* Now feed data into the reader until we reach the end: */ modifier_progressive_read(d.pm, pp, pi); } else { /* modifier_read expects a png_modifier* */ png_set_read_fn(pp, d.pm, modifier_read);
/* Check the header values: */ png_read_info(pp, pi);
/* Process the 'info' requirements. Only one image is generated */ transform_info_imp(&d, pp, pi);
sequential_row(&d.this, pp, pi, NULL, d.this.ps->image);
transform_image_validate(&d, pp, pi, d.this.ps->image); }
modifier_reset(d.pm); }
Catch(fault) modifier_reset((png_modifier*)fault);}
/* The transforms: */#define ITSTRUCT(name) image_transform_##name
#define IT(name,prev)\
static image_transform ITSTRUCT(name) =\{\ #name,\
1, /*enable*/\ &ITSTRUCT(prev), /*list*/\ 0, /*global_use*/\ 0, /*local_use*/\ 0, /*next*/\ image_transform_png_set_##name##_set,\ image_transform_png_set_##name##_mod,\ image_transform_png_set_##name##_add\}
/* To save code: */static intimage_transform_default_add(image_transform *this, PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth){ UNUSED(colour_type) UNUSED(bit_depth)
this->next = *that; *that = this;
return 1;}
/* png_set_palette_to_rgb */static voidimage_transform_png_set_palette_to_rgb_set(PNG_CONST image_transform *this, transform_display *that, png_structp pp, png_infop pi){ png_set_palette_to_rgb(pp); this->next->set(this->next, that, pp, pi);}
static voidimage_transform_png_set_palette_to_rgb_mod(PNG_CONST image_transform *this, image_pixel *that, png_structp pp, PNG_CONST transform_display *display){ if (that->colour_type == PNG_COLOR_TYPE_PALETTE) image_pixel_convert_PLTE(that, &display->this);
this->next->mod(this->next, that, pp, display);}
static intimage_transform_png_set_palette_to_rgb_add(image_transform *this, PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth){ UNUSED(bit_depth)
this->next = *that; *that = this;
return colour_type == PNG_COLOR_TYPE_PALETTE;}
IT(palette_to_rgb, end);
/* png_set_tRNS_to_alpha */static voidimage_transform_png_set_tRNS_to_alpha_set(PNG_CONST image_transform *this, transform_display *that, png_structp pp, png_infop pi){ png_set_tRNS_to_alpha(pp); this->next->set(this->next, that, pp, pi);}
static voidimage_transform_png_set_tRNS_to_alpha_mod(PNG_CONST image_transform *this, image_pixel *that, png_structp pp, PNG_CONST transform_display *display){ /* LIBPNG BUG: this always forces palette images to RGB. */ if (that->colour_type == PNG_COLOR_TYPE_PALETTE) image_pixel_convert_PLTE(that, &display->this);
/* This effectively does an 'expand' only if there is some transparency to
* covert to an alpha channel. */ if (that->have_tRNS) image_pixel_add_alpha(that, &display->this);
/* LIBPNG BUG: otherwise libpng still expands to 8 bits! */ else { if (that->bit_depth < 8) that->bit_depth =8; if (that->sample_depth < 8) that->sample_depth = 8; }
this->next->mod(this->next, that, pp, display);}
static intimage_transform_png_set_tRNS_to_alpha_add(image_transform *this, PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth){ UNUSED(bit_depth)
this->next = *that; *that = this;
/* We don't know yet whether there will be a tRNS chunk, but we know that
* this transformation should do nothing if there already is an alpha * channel. */ return (colour_type & PNG_COLOR_MASK_ALPHA) == 0;}
IT(tRNS_to_alpha,palette_to_rgb);
/* png_set_gray_to_rgb */static voidimage_transform_png_set_gray_to_rgb_set(PNG_CONST image_transform *this, transform_display *that, png_structp pp, png_infop pi){ png_set_gray_to_rgb(pp); this->next->set(this->next, that, pp, pi);}
static voidimage_transform_png_set_gray_to_rgb_mod(PNG_CONST image_transform *this, image_pixel *that, png_structp pp, PNG_CONST transform_display *display){ /* NOTE: we can actually pend the tRNS processing at this point because we
* can correctly recognize the original pixel value even though we have * mapped the one gray channel to the three RGB ones, but in fact libpng * doesn't do this, so we don't either. */ if ((that->colour_type & PNG_COLOR_MASK_COLOR) == 0 && that->have_tRNS) image_pixel_add_alpha(that, &display->this);
/* Simply expand the bit depth and alter the colour type as required. */ if (that->colour_type == PNG_COLOR_TYPE_GRAY) { /* RGB images have a bit depth at least equal to '8' */ if (that->bit_depth < 8) that->sample_depth = that->bit_depth = 8;
/* And just changing the colour type works here because the green and blue
* channels are being maintained in lock-step with the red/gray: */ that->colour_type = PNG_COLOR_TYPE_RGB; }
else if (that->colour_type == PNG_COLOR_TYPE_GRAY_ALPHA) that->colour_type = PNG_COLOR_TYPE_RGB_ALPHA;
this->next->mod(this->next, that, pp, display);}
static intimage_transform_png_set_gray_to_rgb_add(image_transform *this, PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth){ UNUSED(bit_depth)
this->next = *that; *that = this;
return (colour_type & PNG_COLOR_MASK_COLOR) == 0;}
IT(gray_to_rgb,tRNS_to_alpha);
/* png_set_expand */static voidimage_transform_png_set_expand_set(PNG_CONST image_transform *this, transform_display *that, png_structp pp, png_infop pi){ png_set_expand(pp); this->next->set(this->next, that, pp, pi);}
static voidimage_transform_png_set_expand_mod(PNG_CONST image_transform *this, image_pixel *that, png_structp pp, PNG_CONST transform_display *display){ /* The general expand case depends on what the colour type is: */ if (that->colour_type == PNG_COLOR_TYPE_PALETTE) image_pixel_convert_PLTE(that, &display->this); else if (that->bit_depth < 8) /* grayscale */ that->sample_depth = that->bit_depth = 8;
if (that->have_tRNS) image_pixel_add_alpha(that, &display->this);
this->next->mod(this->next, that, pp, display);}
static intimage_transform_png_set_expand_add(image_transform *this, PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth){ UNUSED(bit_depth)
this->next = *that; *that = this;
/* 'expand' should do nothing for RGBA or GA input - no tRNS and the bit
* depth is at least 8 already. */ return (colour_type & PNG_COLOR_MASK_ALPHA) == 0;}
IT(expand,gray_to_rgb);
/* png_set_expand_gray_1_2_4_to_8
* LIBPNG BUG: this just does an 'expand' */static voidimage_transform_png_set_expand_gray_1_2_4_to_8_set( PNG_CONST image_transform *this, transform_display *that, png_structp pp, png_infop pi){ png_set_expand_gray_1_2_4_to_8(pp); this->next->set(this->next, that, pp, pi);}
static voidimage_transform_png_set_expand_gray_1_2_4_to_8_mod( PNG_CONST image_transform *this, image_pixel *that, png_structp pp, PNG_CONST transform_display *display){ image_transform_png_set_expand_mod(this, that, pp, display);}
static intimage_transform_png_set_expand_gray_1_2_4_to_8_add(image_transform *this, PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth){ return image_transform_png_set_expand_add(this, that, colour_type, bit_depth);}
IT(expand_gray_1_2_4_to_8, expand);/* png_set_expand_16 */static voidimage_transform_png_set_expand_16_set(PNG_CONST image_transform *this, transform_display *that, png_structp pp, png_infop pi){ png_set_expand_16(pp); this->next->set(this->next, that, pp, pi);}
static voidimage_transform_png_set_expand_16_mod(PNG_CONST image_transform *this, image_pixel *that, png_structp pp, PNG_CONST transform_display *display){ /* Expect expand_16 to expand everything to 16 bits as a result of also
* causing 'expand' to happen. */ if (that->colour_type == PNG_COLOR_TYPE_PALETTE) image_pixel_convert_PLTE(that, &display->this);
if (that->have_tRNS) image_pixel_add_alpha(that, &display->this);
if (that->bit_depth < 16) that->sample_depth = that->bit_depth = 16;
this->next->mod(this->next, that, pp, display);}
static intimage_transform_png_set_expand_16_add(image_transform *this, PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth){ UNUSED(colour_type)
this->next = *that; *that = this;
/* expand_16 does something unless the bit depth is already 16. */ return bit_depth < 16;}
IT(expand_16, expand_gray_1_2_4_to_8);
/* png_set_strip_16 */static voidimage_transform_png_set_strip_16_set(PNG_CONST image_transform *this, transform_display *that, png_structp pp, png_infop pi){ png_set_strip_16(pp); this->next->set(this->next, that, pp, pi);}
static voidimage_transform_png_set_strip_16_mod(PNG_CONST image_transform *this, image_pixel *that, png_structp pp, PNG_CONST transform_display *display){ if (that->bit_depth == 16) { that->sample_depth = that->bit_depth = 8; if (that->red_sBIT > 8) that->red_sBIT = 8; if (that->green_sBIT > 8) that->green_sBIT = 8; if (that->blue_sBIT > 8) that->blue_sBIT = 8; if (that->alpha_sBIT > 8) that->alpha_sBIT = 8;
# ifndef PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
/* The strip 16 algoirithm drops the low 8 bits rather than calculating
* 1/257, so we need to adjust the permitted errors appropriately: */ { PNG_CONST double d = (255-128.5)/65535; that->rede += d; that->greene += d; that->bluee += d; that->alphae += d; }# endif
}
this->next->mod(this->next, that, pp, display);}
static intimage_transform_png_set_strip_16_add(image_transform *this, PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth){ UNUSED(colour_type)
this->next = *that; *that = this;
return bit_depth > 8;}
IT(strip_16, expand_16);
/* png_set_strip_alpha */static voidimage_transform_png_set_strip_alpha_set(PNG_CONST image_transform *this, transform_display *that, png_structp pp, png_infop pi){ png_set_strip_alpha(pp); this->next->set(this->next, that, pp, pi);}
static voidimage_transform_png_set_strip_alpha_mod(PNG_CONST image_transform *this, image_pixel *that, png_structp pp, PNG_CONST transform_display *display){ if (that->colour_type == PNG_COLOR_TYPE_GRAY_ALPHA) that->colour_type = PNG_COLOR_TYPE_GRAY; else if (that->colour_type == PNG_COLOR_TYPE_RGB_ALPHA) that->colour_type = PNG_COLOR_TYPE_RGB;
that->have_tRNS = 0; that->alphaf = 1; that->alphae = 0;
this->next->mod(this->next, that, pp, display);}
static intimage_transform_png_set_strip_alpha_add(image_transform *this, PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth){ UNUSED(bit_depth)
this->next = *that; *that = this;
return (colour_type & PNG_COLOR_MASK_ALPHA) != 0;}
IT(strip_alpha,strip_16);
/* png_set_rgb_to_gray(png_structp, int err_action, double red, double green)
* png_set_rgb_to_gray_fixed(png_structp, int err_action, png_fixed_point red, * png_fixed_point green) * png_get_rgb_to_gray_status * * At present the APIs are simply tested using the 16.16 fixed point conversion * values known to be used inside libpng: * * red: 6968 * green: 23434 * blue: 2366 * * NOTE: this currently ignores the gamma because no gamma is being set, the * tests on gamma need to happen in the gamma test set. */static voidimage_transform_png_set_rgb_to_gray_set(PNG_CONST image_transform *this, transform_display *that, png_structp pp, png_infop pi){ PNG_CONST int error_action = 1; /* no error, no defines in png.h */
# ifdef PNG_FLOATING_POINT_SUPPORTED
png_set_rgb_to_gray(pp, error_action, -1, -1);# else
png_set_rgb_to_gray_fixed(pp, error_action, -1, -1);# endif
this->next->set(this->next, that, pp, pi);}
static voidimage_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this, image_pixel *that, png_structp pp, PNG_CONST transform_display *display){ if ((that->colour_type & PNG_COLOR_MASK_COLOR) != 0) { if (that->colour_type == PNG_COLOR_TYPE_PALETTE) image_pixel_convert_PLTE(that, &display->this);
/* Image now has RGB channels... */ that->bluef = that->greenf = that->redf = (that->redf * 6968 + that->greenf * 23434 + that->bluef * 2366) / 32768; that->bluee = that->greene = that->rede = (that->rede * 6968 + that->greene * 23434 + that->bluee * 2366) / 32768 * (1 + DBL_EPSILON * 6);
/* The sBIT is the minium of the three colour channel sBITs. */ if (that->red_sBIT > that->green_sBIT) that->red_sBIT = that->green_sBIT; if (that->red_sBIT > that->blue_sBIT) that->red_sBIT = that->blue_sBIT; that->blue_sBIT = that->green_sBIT = that->red_sBIT;
/* And zap the colour bit in the type: */ if (that->colour_type == PNG_COLOR_TYPE_RGB) that->colour_type = PNG_COLOR_TYPE_GRAY; else if (that->colour_type == PNG_COLOR_TYPE_RGB_ALPHA) that->colour_type = PNG_COLOR_TYPE_GRAY_ALPHA; }
this->next->mod(this->next, that, pp, display);}
static intimage_transform_png_set_rgb_to_gray_add(image_transform *this, PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth){ UNUSED(bit_depth)
this->next = *that; *that = this;
return (colour_type & PNG_COLOR_MASK_COLOR) != 0;}
IT(rgb_to_gray,strip_alpha);
/* png_set_background(png_structp, png_const_color_16p background_color,
* int background_gamma_code, int need_expand, double background_gamma) * png_set_background_fixed(png_structp, png_const_color_16p background_color, * int background_gamma_code, int need_expand, * png_fixed_point background_gamma) * * As with rgb_to_gray this ignores the gamma.*/static voidimage_transform_png_set_background_set(PNG_CONST image_transform *this, transform_display *that, png_structp pp, png_infop pi){ png_color_16 back;
/* Since we don't know the output bit depth at this point we must use the
* input values and ask libpng to expand the chunk as required. */ back.index = 255; /* Should not be used */ back.gray = back.blue = back.green = back.red = (png_uint_16)((1U << that->this.bit_depth) >> 1);
# ifdef PNG_FLOATING_POINT_SUPPORTED
png_set_background(pp, &back, PNG_BACKGROUND_GAMMA_FILE, 1, 0);# else
png_set_background_fixed(pp, &back, PNG_BACKGROUND_GAMMA_FILE, 1, 0);# endif
this->next->set(this->next, that, pp, pi);}
static voidimage_transform_png_set_background_mod(PNG_CONST image_transform *this, image_pixel *that, png_structp pp, PNG_CONST transform_display *display){ /* Check for tRNS first: */ if (that->have_tRNS && that->colour_type != PNG_COLOR_TYPE_PALETTE) image_pixel_add_alpha(that, &display->this);
/* This is only necessary if the alpha value is less than 1. */ if (that->alphaf < 1) { /* Repeat the calculation above and scale the result: */ unsigned int tmp = (1U << display->this.bit_depth); double component = (tmp >> 1)/(double)(tmp-1);
/* Now we do the background calculation without any gamma correction. */ if (that->alphaf <= 0) { that->bluef = that->greenf = that->redf = component; that->bluee = that->greene = that->rede = component * DBL_EPSILON; that->blue_sBIT = that->green_sBIT = that->red_sBIT = that->bit_depth; }
else { component *= 1-that->alphaf; that->redf = that->redf * that->alphaf + component; that->rede = that->rede * that->alphaf + that->redf * 3 * DBL_EPSILON; that->greenf = that->greenf * that->alphaf + component; that->greene = that->greene * that->alphaf + that->greenf * 3 * DBL_EPSILON; that->bluef = that->bluef * that->alphaf + component; that->bluee = that->bluee * that->alphaf + that->bluef * 3 * DBL_EPSILON; }
/* Remove the alpha type and set the alpha. */ that->alphaf = 1; that->alphae = 0;
if (that->colour_type == PNG_COLOR_TYPE_RGB_ALPHA) that->colour_type = PNG_COLOR_TYPE_RGB; else if (that->colour_type == PNG_COLOR_TYPE_GRAY_ALPHA) that->colour_type = PNG_COLOR_TYPE_GRAY; }
this->next->mod(this->next, that, pp, display);}
#define image_transform_png_set_background_add image_transform_default_add
IT(background,rgb_to_gray);
static image_transform *PNG_CONST image_transform_first = &ITSTRUCT(background);
static voidtransform_enable(PNG_CONST char *name){ /* Everything starts out enabled, so if we see an 'enable' disabled
* everything else the first time round. */ static int all_disabled = 0; int found_it = 0; image_transform *list = image_transform_first;
while (list != &image_transform_end) { if (strcmp(list->name, name) == 0) { list->enable = 1; found_it = 1; } else if (!all_disabled) list->enable = 0;
list = list->list; }
all_disabled = 1;
if (!found_it) { fprintf(stderr, "pngvalid: --transform-enable=%s: unknown transform\n", name); exit(1); }}
static voidtransform_disable(PNG_CONST char *name){ image_transform *list = image_transform_first;
while (list != &image_transform_end) { if (strcmp(list->name, name) == 0) { list->enable = 0; return; }
list = list->list; }
fprintf(stderr, "pngvalid: --transform-disable=%s: unknown transform\n", name); exit(1);}
static voidimage_transform_reset_count(void){ image_transform *next = image_transform_first; int count = 0;
while (next != &image_transform_end) { next->local_use = 0; next->next = 0; next = next->list; ++count; }
/* This can only happen if we every have more than 32 transforms (excluding
* the end) in the list. */ if (count > 32) abort();}
static intimage_transform_test_counter(png_uint_32 counter, unsigned int max){ /* Test the list to see if there is any point contining, given a current
* counter and a 'max' value. */ image_transform *next = image_transform_first;
while (next != &image_transform_end) { /* For max 0 or 1 continue until the counter overflows: */ counter >>= 1;
/* Continue if any entry hasn't reacked the max. */ if (max > 1 && next->local_use < max) return 1; next = next->list; }
return max <= 1 && counter == 0;}
static png_uint_32image_transform_add(PNG_CONST image_transform **this, unsigned int max, png_uint_32 counter, char *name, size_t sizeof_name, size_t *pos, png_byte colour_type, png_byte bit_depth){ for (;;) /* until we manage to add something */ { png_uint_32 mask; image_transform *list;
/* Find the next counter value, if the counter is zero this is the start
* of the list. This routine always returns the current counter (not the * next) so it returns 0 at the end and expects 0 at the beginning. */ if (counter == 0) /* first time */ { image_transform_reset_count(); if (max <= 1) counter = 1; else counter = random_32(); } else /* advance the counter */ { switch (max) { case 0: ++counter; break; case 1: counter <<= 1; break; default: counter = random_32(); break; } }
/* Now add all these items, if possible */ *this = &image_transform_end; list = image_transform_first; mask = 1;
/* Go through the whole list adding anything that the counter selects: */ while (list != &image_transform_end) { if ((counter & mask) != 0 && list->enable && (max == 0 || list->local_use < max)) { /* Candidate to add: */ if (list->add(list, this, colour_type, bit_depth) || max == 0) { /* Added, so add to the name too. */ *pos = safecat(name, sizeof_name, *pos, " +"); *pos = safecat(name, sizeof_name, *pos, list->name); }
else { /* Not useful and max>0, so remvoe it from *this: */ *this = list->next; list->next = 0;
/* And, since we know it isn't useful, stop it being added again
* in this run: */ list->local_use = max; } }
mask <<= 1; list = list->list; }
/* Now if anything was added we have something to do. */ if (*this != &image_transform_end) return counter;
/* Nothing added, but was there anything in there to add? */ if (!image_transform_test_counter(counter, max)) return 0; }}
#ifdef THIS_IS_THE_PROFORMA
static voidimage_transform_png_set_@_set(PNG_CONST image_transform *this, transform_display *that, png_structp pp, png_infop pi){ png_set_@(pp); this->next->set(this->next, that, pp, pi);}
static voidimage_transform_png_set_@_mod(PNG_CONST image_transform *this, image_pixel *that, png_structp pp, PNG_CONST transform_display *display){ this->next->mod(this->next, that, pp, display);}
static intimage_transform_png_set_@_add(image_transform *this, PNG_CONST image_transform **that, char *name, size_t sizeof_name, size_t *pos, png_byte colour_type, png_byte bit_depth){ this->next = *that; *that = this;
*pos = safecat(name, sizeof_name, *pos, " +@");
return 1;}
IT(@);#endif
/* png_set_quantize(png_structp, png_colorp palette, int num_palette,
* int maximum_colors, png_const_uint_16p histogram, int full_quantize) * * Very difficult to validate this! *//*NOTE: TBD NYI */
/* The data layout transforms are handled by swapping our own channel data,
* necessarily these need to happen at the end of the transform list because the * semantic of the channels changes after these are executed. Some of these, * like set_shift and set_packing, can't be done at present because they change * the layout of the data at the sub-sample level so sample() won't get the * right answer. *//* png_set_invert_alpha *//*NOTE: TBD NYI */
/* png_set_bgr *//*NOTE: TBD NYI */
/* png_set_swap_alpha *//*NOTE: TBD NYI */
/* png_set_swap *//*NOTE: TBD NYI */
/* png_set_filler, (png_structp png_ptr, png_uint_32 filler, int flags)); *//*NOTE: TBD NYI */
/* png_set_add_alpha, (png_structp png_ptr, png_uint_32 filler, int flags)); *//*NOTE: TBD NYI */
/* png_set_packing *//*NOTE: TBD NYI */
/* png_set_packswap *//*NOTE: TBD NYI */
/* png_set_invert_mono *//*NOTE: TBD NYI */
/* png_set_shift(png_structp, png_const_color_8p true_bits) *//*NOTE: TBD NYI */
static inttest_transform(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type, int bdlo, int PNG_CONST bdhi, png_uint_32 max){ for (; bdlo <= bdhi; ++bdlo) { PNG_CONST png_byte bit_depth = DEPTH(bdlo); png_uint_32 counter = 0; size_t base_pos; char name[64];
base_pos = safecat(name, sizeof name, 0, "transform:");
for (;;) { size_t pos = base_pos; PNG_CONST image_transform *list = 0;
counter = image_transform_add(&list, max, counter, name, sizeof name, &pos, colour_type, bit_depth);
if (counter == 0) break;
/* The command line can change this to checking interlaced images. */ transform_test(pm, FILEID(colour_type, bit_depth, pm->interlace_type, 0, 0, 0), list, name);
if (fail(pm)) return 0; } }
return 1; /* keep going */}
static voidperform_transform_test(png_modifier *pm){ /* Test each colour type over the valid range of bit depths (expressed as
* log2(bit_depth) in turn, stop as soon as any error is detected. */ if (!test_transform(pm, 0, 0, READ_BDHI, 1)) return;
if (!test_transform(pm, 2, 3, READ_BDHI, 1)) return;
if (!test_transform(pm, 3, 0, 3, 1)) return;
if (!test_transform(pm, 4, 3, READ_BDHI, 1)) return;
if (!test_transform(pm, 6, 3, READ_BDHI, 1)) return;}
/********************************* GAMMA TESTS ********************************//* Gamma test images. */typedef struct gamma_modification{ png_modification this; png_fixed_point gamma;} gamma_modification;
static intgamma_modify(png_modifier *pm, png_modification *me, int add){ UNUSED(add) /* This simply dumps the given gamma value into the buffer. */ png_save_uint_32(pm->buffer, 4); png_save_uint_32(pm->buffer+4, CHUNK_gAMA); png_save_uint_32(pm->buffer+8, ((gamma_modification*)me)->gamma); return 1;}
static voidgamma_modification_init(gamma_modification *me, png_modifier *pm, double gammad){ double g;
modification_init(&me->this); me->this.chunk = CHUNK_gAMA; me->this.modify_fn = gamma_modify; me->this.add = CHUNK_PLTE; g = floor(gammad * 100000 + .5); me->gamma = (png_fixed_point)g; me->this.next = pm->modifications; pm->modifications = &me->this;}
typedef struct srgb_modification{ png_modification this; png_byte intent;} srgb_modification;
static intsrgb_modify(png_modifier *pm, png_modification *me, int add){ UNUSED(add) /* As above, ignore add and just make a new chunk */ png_save_uint_32(pm->buffer, 1); png_save_uint_32(pm->buffer+4, CHUNK_sRGB); pm->buffer[8] = ((srgb_modification*)me)->intent; return 1;}
static voidsrgb_modification_init(srgb_modification *me, png_modifier *pm, png_byte intent){ modification_init(&me->this); me->this.chunk = CHUNK_sBIT;
if (intent <= 3) /* if valid, else *delete* sRGB chunks */ { me->this.modify_fn = srgb_modify; me->this.add = CHUNK_PLTE; me->intent = intent; }
else { me->this.modify_fn = 0; me->this.add = 0; me->intent = 0; }
me->this.next = pm->modifications; pm->modifications = &me->this;}
typedef struct sbit_modification{ png_modification this; png_byte sbit;} sbit_modification;
static intsbit_modify(png_modifier *pm, png_modification *me, int add){ png_byte sbit = ((sbit_modification*)me)->sbit; if (pm->bit_depth > sbit) { int cb = 0; switch (pm->colour_type) { case 0: cb = 1; break;
case 2: case 3: cb = 3; break;
case 4: cb = 2; break;
case 6: cb = 4; break;
default: png_error(pm->this.pread, "unexpected colour type in sBIT modification"); }
png_save_uint_32(pm->buffer, cb); png_save_uint_32(pm->buffer+4, CHUNK_sBIT);
while (cb > 0) (pm->buffer+8)[--cb] = sbit;
return 1; } else if (!add) { /* Remove the sBIT chunk */ pm->buffer_count = pm->buffer_position = 0; return 1; } else return 0; /* do nothing */}
static voidsbit_modification_init(sbit_modification *me, png_modifier *pm, png_byte sbit){ modification_init(&me->this); me->this.chunk = CHUNK_sBIT; me->this.modify_fn = sbit_modify; me->this.add = CHUNK_PLTE; me->sbit = sbit; me->this.next = pm->modifications; pm->modifications = &me->this;}
/* Reader callbacks and implementations, where they differ from the standard
* ones. */typedef struct gamma_display{ standard_display this;
/* Parameters */ png_modifier* pm; double file_gamma; double screen_gamma; png_byte sbit; int threshold_test; PNG_CONST char* name; int speed; int use_input_precision; int strip16;
/* Local variables */ double maxerrout; double maxerrpc; double maxerrabs;} gamma_display;
static voidgamma_display_init(gamma_display *dp, png_modifier *pm, png_uint_32 id, double file_gamma, double screen_gamma, png_byte sbit, int threshold_test, int speed, int use_input_precision, int strip16){ /* Standard fields */ standard_display_init(&dp->this, &pm->this, id, 0/*do_interlace*/);
/* Parameter fields */ dp->pm = pm; dp->file_gamma = file_gamma; dp->screen_gamma = screen_gamma; dp->sbit = sbit; dp->threshold_test = threshold_test; dp->speed = speed; dp->use_input_precision = use_input_precision; dp->strip16 = strip16;
/* Local variable fields */ dp->maxerrout = dp->maxerrpc = dp->maxerrabs = 0;}
static voidgamma_info_imp(gamma_display *dp, png_structp pp, png_infop pi){ /* Reuse the standard stuff as appropriate. */ standard_info_part1(&dp->this, pp, pi);
/* If requested strip 16 to 8 bits - this is handled automagically below
* because the output bit depth is read from the library. Note that there * are interactions with sBIT but, internally, libpng makes sbit at most * PNG_MAX_GAMMA_8 when doing the following. */ if (dp->strip16)# ifdef PNG_READ_16_TO_8_SUPPORTED
png_set_strip_16(pp);# else
png_error(pp, "strip16 (16 to 8 bit conversion) not supported");# endif
png_read_update_info(pp, pi);
/* Now we may get a different cbRow: */ standard_info_part2(&dp->this, pp, pi, 1 /*images*/);}
static voidgamma_info(png_structp pp, png_infop pi){ gamma_info_imp(png_get_progressive_ptr(pp), pp, pi);}
static voidgamma_image_validate(gamma_display *dp, png_structp pp, png_infop pi, png_const_bytep pRow){ /* Get some constants derived from the input and output file formats: */ PNG_CONST png_byte sbit = dp->sbit; PNG_CONST double file_gamma = dp->file_gamma; PNG_CONST double screen_gamma = dp->screen_gamma; PNG_CONST int use_input_precision = dp->use_input_precision; PNG_CONST int speed = dp->speed; PNG_CONST png_byte in_ct = dp->this.colour_type; PNG_CONST png_byte in_bd = dp->this.bit_depth; PNG_CONST png_uint_32 w = dp->this.w; PNG_CONST png_uint_32 h = dp->this.h; PNG_CONST size_t cbRow = dp->this.cbRow; PNG_CONST png_byte out_ct = png_get_color_type(pp, pi); PNG_CONST png_byte out_bd = png_get_bit_depth(pp, pi); PNG_CONST unsigned int outmax = (1U<<out_bd)-1; PNG_CONST double maxabs = abserr(dp->pm, out_bd); PNG_CONST double maxout = outerr(dp->pm, out_bd); PNG_CONST double maxpc = pcerr(dp->pm, out_bd);
/* There are three sources of error, firstly the quantization in the
* file encoding, determined by sbit and/or the file depth, secondly * the output (screen) gamma and thirdly the output file encoding. * * Since this API receives the screen and file gamma in double * precision it is possible to calculate an exact answer given an input * pixel value. Therefore we assume that the *input* value is exact - * sample/maxsample - calculate the corresponding gamma corrected * output to the limits of double precision arithmetic and compare with * what libpng returns. * * Since the library must quantize the output to 8 or 16 bits there is * a fundamental limit on the accuracy of the output of +/-.5 - this * quantization limit is included in addition to the other limits * specified by the paramaters to the API. (Effectively, add .5 * everywhere.) * * The behavior of the 'sbit' paramter is defined by section 12.5 * (sample depth scaling) of the PNG spec. That section forces the * decoder to assume that the PNG values have been scaled if sBIT is * present: * * png-sample = floor( input-sample * (max-out/max-in) + .5); * * This means that only a subset of the possible PNG values should * appear in the input. However, the spec allows the encoder to use a * variety of approximations to the above and doesn't require any * restriction of the values produced. * * Nevertheless the spec requires that the upper 'sBIT' bits of the * value stored in a PNG file be the original sample bits. * Consequently the code below simply scales the top sbit bits by * (1<<sbit)-1 to obtain an original sample value. * * Because there is limited precision in the input it is arguable that * an acceptable result is any valid result from input-.5 to input+.5. * The basic tests below do not do this, however if * 'use_input_precision' is set a subsequent test is performed below. */ PNG_CONST int processing = (fabs(screen_gamma*file_gamma-1) >= PNG_GAMMA_THRESHOLD && !dp->threshold_test && !speed && in_ct != 3) || in_bd != out_bd;
PNG_CONST unsigned int samples_per_pixel = (out_ct & 2U) ? 3U : 1U;
PNG_CONST double gamma_correction = 1/(file_gamma*screen_gamma);/* Overall */
double maxerrout = 0, maxerrabs = 0, maxerrpc = 0; png_uint_32 y;
for (y=0; y<h; ++y, pRow += cbRow) { unsigned int s, x; png_byte std[STANDARD_ROWMAX];
transform_row(pp, std, in_ct, in_bd, y);
if (processing) { for (x=0; x<w; ++x) for (s=0; s<samples_per_pixel; ++s) { /* Input sample values: */ PNG_CONST unsigned int id = sample(std, in_ct, in_bd, x, s);
PNG_CONST unsigned int od = sample(pRow, out_ct, out_bd, x, s);
PNG_CONST unsigned int isbit = id >> (in_bd-sbit);
double i, input_sample, encoded_sample, output; double encoded_error, error; double es_lo, es_hi;
/* First check on the 'perfect' result obtained from the
* digitized input value, id, and compare this against the * actual digitized result, 'od'. 'i' is the input result * in the range 0..1: * * NOTE: sBIT should be taken into account here but isn't, * as described above. */ i = isbit; i /= (1U<<sbit)-1;
/* Then get the gamma corrected version of 'i' and compare
* to 'od', any error less than .5 is insignificant - just * quantization of the output value to the nearest digital * value (nevertheless the error is still recorded - it's * interesting ;-) */ encoded_sample = pow(i, gamma_correction) * outmax; encoded_error = fabs(od-encoded_sample);
if (encoded_error > maxerrout) maxerrout = encoded_error;
if (encoded_error < .5+maxout) continue;
/* There may be an error, so calculate the actual sample
* values - unencoded light intensity values. Note that * in practice these are not unencoded because they * include a 'viewing correction' to decrease or * (normally) increase the perceptual contrast of the * image. There's nothing we can do about this - we don't * know what it is - so assume the unencoded value is * perceptually linear. */ input_sample = pow(i, 1/file_gamma); /* In range 0..1 */ output = od; output /= outmax; output = pow(output, screen_gamma);
/* Now we have the numbers for real errors, both absolute
* values as as a percentage of the correct value (output): */ error = fabs(input_sample-output);
if (error > maxerrabs) maxerrabs = error;
/* The following is an attempt to ignore the tendency of
* quantization to dominate the percentage errors for low * output sample values: */ if (input_sample*maxpc > .5+maxabs) { double percentage_error = error/input_sample; if (percentage_error > maxerrpc) maxerrpc = percentage_error; }
/* Now calculate the digitization limits for
* 'encoded_sample' using the 'max' values. Note that * maxout is in the encoded space but maxpc and maxabs are * in linear light space. * * First find the maximum error in linear light space, * range 0..1: */ { double tmp = input_sample * maxpc; if (tmp < maxabs) tmp = maxabs;
/* Low bound - the minimum of the three: */ es_lo = encoded_sample - maxout;
if (es_lo > 0 && input_sample-tmp > 0) { double low_value = outmax * pow(input_sample-tmp, 1/screen_gamma); if (low_value < es_lo) es_lo = low_value; }
else es_lo = 0;
es_hi = encoded_sample + maxout;
if (es_hi < outmax && input_sample+tmp < 1) { double high_value = outmax * pow(input_sample+tmp, 1/screen_gamma); if (high_value > es_hi) es_hi = high_value; }
else es_hi = outmax; }
/* The primary test is that the final encoded value
* returned by the library should be between the two limits * (inclusive) that were calculated above. At this point * quantization of the output must be taken into account. */ if (od+.5 < es_lo || od-.5 > es_hi) { /* There has been an error in processing. */ double is_lo, is_hi;
if (use_input_precision) { /* Ok, something is wrong - this actually happens in
* current libpng sbit processing. Assume that the * input value (id, adjusted for sbit) can be * anywhere between value-.5 and value+.5 - quite a * large range if sbit is low. */ double tmp = (isbit - .5)/((1U<<sbit)-1);
if (tmp > 0) { is_lo = outmax * pow(tmp, gamma_correction) - maxout; if (is_lo < 0) is_lo = 0; }
else is_lo = 0;
tmp = (isbit + .5)/((1U<<sbit)-1);
if (tmp < 1) { is_hi = outmax * pow(tmp, gamma_correction) + maxout; if (is_hi > outmax) is_hi = outmax; }
else is_hi = outmax;
if (!(od+.5 < is_lo || od-.5 > is_hi)) continue; } else is_lo = es_lo, is_hi = es_hi;
{ char msg[256];
sprintf(msg, "error: %.3f; %u{%u;%u} -> %u not %.2f (%.1f-%.1f)", od-encoded_sample, id, sbit, isbit, od, encoded_sample, is_lo, is_hi);
png_warning(pp, msg); } } } }
else if (!speed && memcmp(std, pRow, cbRow) != 0) { char msg[64];
/* No transform is expected on the threshold tests. */ sprintf(msg, "gamma: below threshold row %d changed", y);
png_error(pp, msg); } } /* row (y) loop */
dp->maxerrout = maxerrout; dp->maxerrabs = maxerrabs; dp->maxerrpc = maxerrpc; dp->this.ps->validated = 1;}
static voidgamma_end(png_structp pp, png_infop pi){ gamma_display *dp = png_get_progressive_ptr(pp);
gamma_image_validate(dp, pp, pi, dp->this.ps->image);}
/* A single test run checking a gamma transformation.
* * maxabs: maximum absolute error as a fraction * maxout: maximum output error in the output units * maxpc: maximum percentage error (as a percentage) */static voidgamma_test(png_modifier *pmIn, PNG_CONST png_byte colour_typeIn, PNG_CONST png_byte bit_depthIn, PNG_CONST int interlace_typeIn, PNG_CONST double file_gammaIn, PNG_CONST double screen_gammaIn, PNG_CONST png_byte sbitIn, PNG_CONST int threshold_testIn, PNG_CONST char *name, PNG_CONST int speedIn, PNG_CONST int use_input_precisionIn, PNG_CONST int strip16In){ gamma_display d; context(&pmIn->this, fault);
gamma_display_init(&d, pmIn, FILEID(colour_typeIn, bit_depthIn, interlace_typeIn, 0, 0, 0), file_gammaIn, screen_gammaIn, sbitIn, threshold_testIn, speedIn, use_input_precisionIn, strip16In);
Try { png_structp pp; png_infop pi; gamma_modification gamma_mod; srgb_modification srgb_mod; sbit_modification sbit_mod;
/* Make an appropriate modifier to set the PNG file gamma to the
* given gamma value and the sBIT chunk to the given precision. */ d.pm->modifications = NULL; gamma_modification_init(&gamma_mod, d.pm, d.file_gamma); srgb_modification_init(&srgb_mod, d.pm, 127 /*delete*/); sbit_modification_init(&sbit_mod, d.pm, d.sbit);
modification_reset(d.pm->modifications);
/* Get a png_struct for writing the image. */ pp = set_modifier_for_read(d.pm, &pi, d.this.id, name);
/* Set up gamma processing. */#ifdef PNG_FLOATING_POINT_SUPPORTED
png_set_gamma(pp, d.screen_gamma, d.file_gamma);#else
{ png_fixed_point s = floor(d.screen_gamma*100000+.5); png_fixed_point f = floor(d.file_gamma*100000+.5); png_set_gamma_fixed(pp, s, f); }#endif
/* Introduce the correct read function. */ if (d.pm->this.progressive) { /* Share the row function with the standard implementation. */ png_set_progressive_read_fn(pp, &d, gamma_info, progressive_row, gamma_end);
/* Now feed data into the reader until we reach the end: */ modifier_progressive_read(d.pm, pp, pi); } else { /* modifier_read expects a png_modifier* */ png_set_read_fn(pp, d.pm, modifier_read);
/* Check the header values: */ png_read_info(pp, pi);
/* Process the 'info' requirements. Only one image is generated */ gamma_info_imp(&d, pp, pi);
sequential_row(&d.this, pp, pi, NULL, d.this.ps->image);
gamma_image_validate(&d, pp, pi, d.this.ps->image); }
modifier_reset(d.pm);
if (d.pm->log && !d.threshold_test && !d.speed) fprintf(stderr, "%d bit %s %s: max error %f (%.2g, %2g%%)\n", d.this.bit_depth, colour_types[d.this.colour_type], d.name, d.maxerrout, d.maxerrabs, 100*d.maxerrpc);
/* Log the summary values too. */ if (d.this.colour_type == 0 || d.this.colour_type == 4) { switch (d.this.bit_depth) { case 1: break;
case 2: if (d.maxerrout > d.pm->error_gray_2) d.pm->error_gray_2 = d.maxerrout;
break;
case 4: if (d.maxerrout > d.pm->error_gray_4) d.pm->error_gray_4 = d.maxerrout;
break;
case 8: if (d.maxerrout > d.pm->error_gray_8) d.pm->error_gray_8 = d.maxerrout;
break;
case 16: if (d.maxerrout > d.pm->error_gray_16) d.pm->error_gray_16 = d.maxerrout;
break;
default: png_error(pp, "bad bit depth (internal: 1)"); } }
else if (d.this.colour_type == 2 || d.this.colour_type == 6) { switch (d.this.bit_depth) { case 8:
if (d.maxerrout > d.pm->error_color_8) d.pm->error_color_8 = d.maxerrout;
break;
case 16:
if (d.maxerrout > d.pm->error_color_16) d.pm->error_color_16 = d.maxerrout;
break;
default: png_error(pp, "bad bit depth (internal: 2)"); } } }
Catch(fault) modifier_reset((png_modifier*)fault);}
static void gamma_threshold_test(png_modifier *pm, png_byte colour_type, png_byte bit_depth, int interlace_type, double file_gamma, double screen_gamma){ size_t pos = 0; char name[64]; pos = safecat(name, sizeof name, pos, "threshold "); pos = safecatd(name, sizeof name, pos, file_gamma, 3); pos = safecat(name, sizeof name, pos, "/"); pos = safecatd(name, sizeof name, pos, screen_gamma, 3);
(void)gamma_test(pm, colour_type, bit_depth, interlace_type, file_gamma, screen_gamma, bit_depth, 1, name, 0 /*speed*/, 0 /*no input precision*/, 0 /*no strip16*/);}
static voidperform_gamma_threshold_tests(png_modifier *pm){ png_byte colour_type = 0; png_byte bit_depth = 0;
while (next_format(&colour_type, &bit_depth)) { double test_gamma = 1.0; while (test_gamma >= .4) { /* There's little point testing the interlacing vs non-interlacing,
* but this can be set from the command line. */ gamma_threshold_test(pm, colour_type, bit_depth, pm->interlace_type, test_gamma, 1/test_gamma); test_gamma *= .95; }
/* And a special test for sRGB */ gamma_threshold_test(pm, colour_type, bit_depth, pm->interlace_type, .45455, 2.2);
if (fail(pm)) return; }}
static void gamma_transform_test(png_modifier *pm, PNG_CONST png_byte colour_type, PNG_CONST png_byte bit_depth, PNG_CONST int interlace_type, PNG_CONST double file_gamma, PNG_CONST double screen_gamma, PNG_CONST png_byte sbit, PNG_CONST int speed, PNG_CONST int use_input_precision, PNG_CONST int strip16){ size_t pos = 0; char name[64];
if (sbit != bit_depth) { pos = safecat(name, sizeof name, pos, "sbit("); pos = safecatn(name, sizeof name, pos, sbit); pos = safecat(name, sizeof name, pos, ") "); }
else pos = safecat(name, sizeof name, pos, "gamma ");
if (strip16) pos = safecat(name, sizeof name, pos, "16to8 ");
pos = safecatd(name, sizeof name, pos, file_gamma, 3); pos = safecat(name, sizeof name, pos, "->"); pos = safecatd(name, sizeof name, pos, screen_gamma, 3);
gamma_test(pm, colour_type, bit_depth, interlace_type, file_gamma, screen_gamma, sbit, 0, name, speed, use_input_precision, strip16);}
static void perform_gamma_transform_tests(png_modifier *pm, int speed){ png_byte colour_type = 0; png_byte bit_depth = 0;
/* Ignore palette images - the gamma correction happens on the palette entry,
* haven't got the tests for this yet. */ while (next_format(&colour_type, &bit_depth)) if (colour_type != 3) { unsigned int i, j;
for (i=0; i<pm->ngammas; ++i) for (j=0; j<pm->ngammas; ++j) if (i != j) { gamma_transform_test(pm, colour_type, bit_depth, pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], bit_depth, speed, pm->use_input_precision, 0 /*do not strip16*/);
if (fail(pm)) return; } }}
static void perform_gamma_sbit_tests(png_modifier *pm, int speed){ png_byte sbit;
/* The only interesting cases are colour and grayscale, alpha is ignored here
* for overall speed. Only bit depths 8 and 16 are tested. */ for (sbit=pm->sbitlow; sbit<(1<<READ_BDHI); ++sbit) { unsigned int i, j;
for (i=0; i<pm->ngammas; ++i) { for (j=0; j<pm->ngammas; ++j) { if (i != j) { if (sbit < 8) { gamma_transform_test(pm, 0, 8, pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], sbit, speed, pm->use_input_precision_sbit, 0 /*strip16*/);
if (fail(pm)) return;
gamma_transform_test(pm, 2, 8, pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], sbit, speed, pm->use_input_precision_sbit, 0 /*strip16*/);
if (fail(pm)) return; }
#ifdef DO_16BIT
gamma_transform_test(pm, 0, 16, pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], sbit, speed, pm->use_input_precision_sbit, 0 /*strip16*/);
if (fail(pm)) return;
gamma_transform_test(pm, 2, 16, pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], sbit, speed, pm->use_input_precision_sbit, 0 /*strip16*/);
if (fail(pm)) return;#endif
} } } }}
/* Note that this requires a 16 bit source image but produces 8 bit output, so
* we only need the 16bit write support. */#ifdef PNG_READ_16_TO_8_SUPPORTED
static void perform_gamma_strip16_tests(png_modifier *pm, int speed){# ifndef PNG_MAX_GAMMA_8
# define PNG_MAX_GAMMA_8 11
# endif
/* Include the alpha cases here. Note that sbit matches the internal value
* used by the library - otherwise we will get spurious errors from the * internal sbit style approximation. * * The threshold test is here because otherwise the 16 to 8 conversion will * proceed *without* gamma correction, and the tests above will fail (but not * by much) - this could be fixed, it only appears with the -g option. */ unsigned int i, j; for (i=0; i<pm->ngammas; ++i) { for (j=0; j<pm->ngammas; ++j) { if (i != j && fabs(pm->gammas[j]/pm->gammas[i]-1) >= PNG_GAMMA_THRESHOLD) { gamma_transform_test(pm, 0, 16, pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], PNG_MAX_GAMMA_8, speed, pm->use_input_precision_16to8, 1 /*strip16*/);
if (fail(pm)) return;
gamma_transform_test(pm, 2, 16, pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], PNG_MAX_GAMMA_8, speed, pm->use_input_precision_16to8, 1 /*strip16*/);
if (fail(pm)) return;
gamma_transform_test(pm, 4, 16, pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], PNG_MAX_GAMMA_8, speed, pm->use_input_precision_16to8, 1 /*strip16*/);
if (fail(pm)) return;
gamma_transform_test(pm, 6, 16, pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], PNG_MAX_GAMMA_8, speed, pm->use_input_precision_16to8, 1 /*strip16*/);
if (fail(pm)) return; } } }}#endif /* 16 to 8 bit conversion */
static voidperform_gamma_test(png_modifier *pm, int speed, int summary){ /* First some arbitrary no-transform tests: */ if (!speed && pm->test_gamma_threshold) { perform_gamma_threshold_tests(pm);
if (fail(pm)) return; }
/* Now some real transforms. */ if (pm->test_gamma_transform) { perform_gamma_transform_tests(pm, speed);
if (summary) { printf("Gamma correction error summary\n\n"); printf("The printed value is the maximum error in the pixel values\n"); printf("calculated by the libpng gamma correction code. The error\n"); printf("is calculated as the difference between the output pixel\n"); printf("value (always an integer) and the ideal value from the\n"); printf("libpng specification (typically not an integer).\n\n");
printf("Expect this value to be less than .5 for 8 bit formats,\n"); printf("less than 1 for formats with fewer than 8 bits and a small\n"); printf("number (typically less than 5) for the 16 bit formats.\n"); printf("For performance reasons the value for 16 bit formats\n"); printf("increases when the image file includes an sBIT chunk.\n\n");
printf(" 2 bit gray: %.5f\n", pm->error_gray_2); printf(" 4 bit gray: %.5f\n", pm->error_gray_4); printf(" 8 bit gray: %.5f\n", pm->error_gray_8); printf(" 8 bit color: %.5f\n", pm->error_color_8);#ifdef DO_16BIT
printf(" 16 bit gray: %.5f\n", pm->error_gray_16); printf(" 16 bit color: %.5f\n", pm->error_color_16);#endif
} }
/* The sbit tests produce much larger errors: */ if (pm->test_gamma_sbit) { pm->error_gray_2 = pm->error_gray_4 = pm->error_gray_8 = pm->error_gray_16 = pm->error_color_8 = pm->error_color_16 = 0; perform_gamma_sbit_tests(pm, speed);
if (summary) { printf("Gamma correction with sBIT:\n");
if (pm->sbitlow < 8U) { printf(" 2 bit gray: %.5f\n", pm->error_gray_2); printf(" 4 bit gray: %.5f\n", pm->error_gray_4); printf(" 8 bit gray: %.5f\n", pm->error_gray_8); printf(" 8 bit color: %.5f\n", pm->error_color_8); }
#ifdef DO_16BIT
printf(" 16 bit gray: %.5f\n", pm->error_gray_16); printf(" 16 bit color: %.5f\n", pm->error_color_16); #endif
} }
#ifdef PNG_READ_16_TO_8_SUPPORTED
if (pm->test_gamma_strip16) { /* The 16 to 8 bit strip operations: */ pm->error_gray_2 = pm->error_gray_4 = pm->error_gray_8 = pm->error_gray_16 = pm->error_color_8 = pm->error_color_16 = 0; perform_gamma_strip16_tests(pm, speed);
if (summary) { printf("Gamma correction with 16 to 8 bit reduction:\n"); printf(" 16 bit gray: %.5f\n", pm->error_gray_16); printf(" 16 bit color: %.5f\n", pm->error_color_16); } }#endif
}
/* INTERLACE MACRO VALIDATION *//* This is copied verbatim from the specification, it is simply the pass
* number in which each pixel in each 8x8 tile appears. The array must * be indexed adam7[y][x] and notice that the pass numbers are based at * 1, not 0 - the base libpng uses. */static PNG_CONSTpng_byte adam7[8][8] ={ { 1,6,4,6,2,6,4,6 }, { 7,7,7,7,7,7,7,7 }, { 5,6,5,6,5,6,5,6 }, { 7,7,7,7,7,7,7,7 }, { 3,6,4,6,3,6,4,6 }, { 7,7,7,7,7,7,7,7 }, { 5,6,5,6,5,6,5,6 }, { 7,7,7,7,7,7,7,7 }};
/* This routine validates all the interlace support macros in png.h for
* a variety of valid PNG widths and heights. It uses a number of similarly * named internal routines that feed off the above array. */static png_uint_32png_pass_start_row(int pass){ int x, y; ++pass; for (y=0; y<8; ++y) for (x=0; x<8; ++x) if (adam7[y][x] == pass) return y; return 0xf;}
static png_uint_32png_pass_start_col(int pass){ int x, y; ++pass; for (x=0; x<8; ++x) for (y=0; y<8; ++y) if (adam7[y][x] == pass) return x; return 0xf;}
static intpng_pass_row_shift(int pass){ int x, y, base=(-1), inc=8; ++pass; for (y=0; y<8; ++y) for (x=0; x<8; ++x) if (adam7[y][x] == pass) { if (base == (-1)) base = y; else if (base == y) {} else if (inc == y-base) base=y; else if (inc == 8) inc = y-base, base=y; else if (inc != y-base) return 0xff; /* error - more than one 'inc' value! */ }
if (base == (-1)) return 0xfe; /* error - no row in pass! */
/* The shift is always 1, 2 or 3 - no pass has all the rows! */ switch (inc) {case 2: return 1;case 4: return 2;case 8: return 3;default: break; }
/* error - unrecognized 'inc' */ return (inc << 8) + 0xfd;}
static intpng_pass_col_shift(int pass){ int x, y, base=(-1), inc=8; ++pass; for (x=0; x<8; ++x) for (y=0; y<8; ++y) if (adam7[y][x] == pass) { if (base == (-1)) base = x; else if (base == x) {} else if (inc == x-base) base=x; else if (inc == 8) inc = x-base, base=x; else if (inc != x-base) return 0xff; /* error - more than one 'inc' value! */ }
if (base == (-1)) return 0xfe; /* error - no row in pass! */
/* The shift is always 1, 2 or 3 - no pass has all the rows! */ switch (inc) {case 1: return 0; /* pass 7 has all the columns */case 2: return 1;case 4: return 2;case 8: return 3;default: break; }
/* error - unrecognized 'inc' */ return (inc << 8) + 0xfd;}
static png_uint_32png_row_from_pass_row(png_uint_32 yIn, int pass){ /* By examination of the array: */ switch (pass) {case 0: return yIn * 8;case 1: return yIn * 8;case 2: return yIn * 8 + 4;case 3: return yIn * 4;case 4: return yIn * 4 + 2;case 5: return yIn * 2;case 6: return yIn * 2 + 1;default: break; }
return 0xff; /* bad pass number */}
static png_uint_32png_col_from_pass_col(png_uint_32 xIn, int pass){ /* By examination of the array: */ switch (pass) {case 0: return xIn * 8;case 1: return xIn * 8 + 4;case 2: return xIn * 4;case 3: return xIn * 4 + 2;case 4: return xIn * 2;case 5: return xIn * 2 + 1;case 6: return xIn;default: break; }
return 0xff; /* bad pass number */}
static intpng_row_in_interlace_pass(png_uint_32 y, int pass){ /* Is row 'y' in pass 'pass'? */ int x; y &= 7; ++pass; for (x=0; x<8; ++x) if (adam7[y][x] == pass) return 1;
return 0;}
static intpng_col_in_interlace_pass(png_uint_32 x, int pass){ /* Is column 'x' in pass 'pass'? */ int y; x &= 7; ++pass; for (y=0; y<8; ++y) if (adam7[y][x] == pass) return 1;
return 0;}
static png_uint_32png_pass_rows(png_uint_32 height, int pass){ png_uint_32 tiles = height>>3; png_uint_32 rows = 0; unsigned int x, y;
height &= 7; ++pass; for (y=0; y<8; ++y) for (x=0; x<8; ++x) if (adam7[y][x] == pass) { rows += tiles; if (y < height) ++rows; break; /* i.e. break the 'x', column, loop. */ }
return rows;}
static png_uint_32png_pass_cols(png_uint_32 width, int pass){ png_uint_32 tiles = width>>3; png_uint_32 cols = 0; unsigned int x, y;
width &= 7; ++pass; for (x=0; x<8; ++x) for (y=0; y<8; ++y) if (adam7[y][x] == pass) { cols += tiles; if (x < width) ++cols; break; /* i.e. break the 'y', row, loop. */ }
return cols;}
static voidperform_interlace_macro_validation(void){ /* The macros to validate, first those that depend only on pass:
* * PNG_PASS_START_ROW(pass) * PNG_PASS_START_COL(pass) * PNG_PASS_ROW_SHIFT(pass) * PNG_PASS_COL_SHIFT(pass) */ int pass;
for (pass=0; pass<7; ++pass) { png_uint_32 m, f, v;
m = PNG_PASS_START_ROW(pass); f = png_pass_start_row(pass); if (m != f) { fprintf(stderr, "PNG_PASS_START_ROW(%d) = %u != %x\n", pass, m, f); exit(1); }
m = PNG_PASS_START_COL(pass); f = png_pass_start_col(pass); if (m != f) { fprintf(stderr, "PNG_PASS_START_COL(%d) = %u != %x\n", pass, m, f); exit(1); }
m = PNG_PASS_ROW_SHIFT(pass); f = png_pass_row_shift(pass); if (m != f) { fprintf(stderr, "PNG_PASS_ROW_SHIFT(%d) = %u != %x\n", pass, m, f); exit(1); }
m = PNG_PASS_COL_SHIFT(pass); f = png_pass_col_shift(pass); if (m != f) { fprintf(stderr, "PNG_PASS_COL_SHIFT(%d) = %u != %x\n", pass, m, f); exit(1); }
/* Macros that depend on the image or sub-image height too:
* * PNG_PASS_ROWS(height, pass) * PNG_PASS_COLS(width, pass) * PNG_ROW_FROM_PASS_ROW(yIn, pass) * PNG_COL_FROM_PASS_COL(xIn, pass) * PNG_ROW_IN_INTERLACE_PASS(y, pass) * PNG_COL_IN_INTERLACE_PASS(x, pass) */ for (v=0;;) { /* First the base 0 stuff: */ m = PNG_ROW_FROM_PASS_ROW(v, pass); f = png_row_from_pass_row(v, pass); if (m != f) { fprintf(stderr, "PNG_ROW_FROM_PASS_ROW(%u, %d) = %u != %x\n", v, pass, m, f); exit(1); }
m = PNG_COL_FROM_PASS_COL(v, pass); f = png_col_from_pass_col(v, pass); if (m != f) { fprintf(stderr, "PNG_COL_FROM_PASS_COL(%u, %d) = %u != %x\n", v, pass, m, f); exit(1); }
m = PNG_ROW_IN_INTERLACE_PASS(v, pass); f = png_row_in_interlace_pass(v, pass); if (m != f) { fprintf(stderr, "PNG_ROW_IN_INTERLACE_PASS(%u, %d) = %u != %x\n", v, pass, m, f); exit(1); }
m = PNG_COL_IN_INTERLACE_PASS(v, pass); f = png_col_in_interlace_pass(v, pass); if (m != f) { fprintf(stderr, "PNG_COL_IN_INTERLACE_PASS(%u, %d) = %u != %x\n", v, pass, m, f); exit(1); }
/* Then the base 1 stuff: */ ++v; m = PNG_PASS_ROWS(v, pass); f = png_pass_rows(v, pass); if (m != f) { fprintf(stderr, "PNG_PASS_ROWS(%u, %d) = %u != %x\n", v, pass, m, f); exit(1); }
m = PNG_PASS_COLS(v, pass); f = png_pass_cols(v, pass); if (m != f) { fprintf(stderr, "PNG_PASS_COLS(%u, %d) = %u != %x\n", v, pass, m, f); exit(1); }
/* Move to the next v - the stepping algorithm starts skipping
* values above 1024. */ if (v > 1024) { if (v == PNG_UINT_31_MAX) break;
v = (v << 1) ^ v; if (v >= PNG_UINT_31_MAX) v = PNG_UINT_31_MAX-1; } } }}
/* main program */int main(int argc, PNG_CONST char **argv){ volatile int summary = 1; /* Print the error summary at the end */
/* Create the given output file on success: */ PNG_CONST char *volatile touch = NULL;
/* This is an array of standard gamma values (believe it or not I've seen
* every one of these mentioned somewhere.) * * In the following list the most useful values are first! */ static double gammas[]={2.2, 1.0, 2.2/1.45, 1.8, 1.5, 2.4, 2.5, 2.62, 2.9};
png_modifier pm; context(&pm.this, fault);
modifier_init(&pm);
/* Preallocate the image buffer, because we know how big it needs to be,
* note that, for testing purposes, it is deliberately mis-aligned. */ pm.this.image = malloc(2*TRANSFORM_IMAGEMAX+1);
if (pm.this.image != NULL) { /* Ignore OOM at this point - the 'ensure' routine above will allocate
* the array appropriately. */ ++(pm.this.image); pm.this.cb_image = 2*TRANSFORM_IMAGEMAX; }
/* Default to error on warning: */ pm.this.treat_warnings_as_errors = 1;
/* Store the test gammas */ pm.gammas = gammas; pm.ngammas = 0; /* default to off */ pm.sbitlow = 8U; /* because libpng doesn't do sBIT below 8! */ pm.use_input_precision_16to8 = 1U; /* Because of the way libpng does it */
/* Some default values (set the behavior for 'make check' here).
* These values simply control the maximum error permitted in the gamma * transformations. The practial limits for human perception are described * below (the setting for maxpc16), however for 8 bit encodings it isn't * possible to meet the accepted capabilities of human vision - i.e. 8 bit * images can never be good enough, regardless of encoding. */ pm.maxout8 = .1; /* Arithmetic error in *encoded* value */ pm.maxabs8 = .00005; /* 1/20000 */ pm.maxpc8 = .499; /* I.e., .499% fractional error */ pm.maxout16 = .499; /* Error in *encoded* value */ pm.maxabs16 = .00005;/* 1/20000 */
/* NOTE: this is a reasonable perceptual limit. We assume that humans can
* perceive light level differences of 1% over a 100:1 range, so we need to * maintain 1 in 10000 accuracy (in linear light space), which is what the * following guarantees. It also allows significantly higher errors at * higher 16 bit values, which is important for performance. The actual * maximum 16 bit error is about +/-1.9 in the fixed point implementation but * this is only allowed for values >38149 by the following: */ pm.maxpc16 = .005; /* I.e., 1/200% - 1/20000 */
/* Now parse the command line options. */ while (--argc >= 1) { if (strcmp(*++argv, "-v") == 0) pm.this.verbose = 1;
else if (strcmp(*argv, "-l") == 0) pm.log = 1;
else if (strcmp(*argv, "-q") == 0) summary = pm.this.verbose = pm.log = 0;
else if (strcmp(*argv, "-w") == 0) pm.this.treat_warnings_as_errors = 0;
else if (strcmp(*argv, "--speed") == 0) pm.this.speed = 1, pm.ngammas = (sizeof gammas)/(sizeof gammas[0]), pm.test_standard = 0;
else if (strcmp(*argv, "--size") == 0) pm.test_size = 1;
else if (strcmp(*argv, "--nosize") == 0) pm.test_size = 0;
else if (strcmp(*argv, "--standard") == 0) pm.test_standard = 1;
else if (strcmp(*argv, "--nostandard") == 0) pm.test_standard = 0;
else if (strcmp(*argv, "--transform") == 0) pm.test_transform = 1;
else if (strcmp(*argv, "--notransform") == 0) pm.test_transform = 0;
else if (strncmp(*argv, "--transform-disable=", sizeof "--transform-disable") == 0) { pm.test_transform = 1; transform_disable(*argv + sizeof "--transform-disable"); }
else if (strncmp(*argv, "--transform-enable=", sizeof "--transform-enable") == 0) { pm.test_transform = 1; transform_enable(*argv + sizeof "--transform-enable"); }
else if (strcmp(*argv, "--gamma") == 0) { /* Just do two gamma tests here (2.2 and linear) for speed: */ pm.ngammas = 2U; pm.test_gamma_threshold = 1; pm.test_gamma_transform = 1; pm.test_gamma_sbit = 1; pm.test_gamma_strip16 = 1; }
else if (strcmp(*argv, "--nogamma") == 0) pm.ngammas = 0;
else if (strcmp(*argv, "--gamma-threshold") == 0) pm.ngammas = 2U, pm.test_gamma_threshold = 1;
else if (strcmp(*argv, "--nogamma-threshold") == 0) pm.test_gamma_threshold = 0;
else if (strcmp(*argv, "--gamma-transform") == 0) pm.ngammas = 2U, pm.test_gamma_transform = 1;
else if (strcmp(*argv, "--nogamma-transform") == 0) pm.test_gamma_transform = 0;
else if (strcmp(*argv, "--gamma-sbit") == 0) pm.ngammas = 2U, pm.test_gamma_sbit = 1;
else if (strcmp(*argv, "--nogamma-sbit") == 0) pm.test_gamma_sbit = 0;
else if (strcmp(*argv, "--gamma-16-to-8") == 0) pm.ngammas = 2U, pm.test_gamma_strip16 = 1;
else if (strcmp(*argv, "--nogamma-16-to-8") == 0) pm.test_gamma_strip16 = 0;
else if (strcmp(*argv, "--all-gammas") == 0) pm.ngammas = (sizeof gammas)/(sizeof gammas[0]);
else if (strcmp(*argv, "--progressive-read") == 0) pm.this.progressive = 1;
else if (strcmp(*argv, "--interlace") == 0) pm.interlace_type = PNG_INTERLACE_ADAM7;
else if (argc >= 1 && strcmp(*argv, "--sbitlow") == 0) --argc, pm.sbitlow = (png_byte)atoi(*++argv);
else if (argc >= 1 && strcmp(*argv, "--touch") == 0) --argc, touch = *++argv;
else if (argc >= 1 && strncmp(*argv, "--max", 4) == 0) { --argc;
if (strcmp(4+*argv, "abs8") == 0) pm.maxabs8 = atof(*++argv);
else if (strcmp(4+*argv, "abs16") == 0) pm.maxabs16 = atof(*++argv);
else if (strcmp(4+*argv, "out8") == 0) pm.maxout8 = atof(*++argv);
else if (strcmp(4+*argv, "out16") == 0) pm.maxout16 = atof(*++argv);
else if (strcmp(4+*argv, "pc8") == 0) pm.maxpc8 = atof(*++argv);
else if (strcmp(4+*argv, "pc16") == 0) pm.maxpc16 = atof(*++argv);
else { fprintf(stderr, "pngvalid: %s: unknown 'max' option\n", *argv); exit(1); } }
else { fprintf(stderr, "pngvalid: %s: unknown argument\n", *argv); exit(1); } }
/* If pngvalid is run with no arguments default to a reasonable set of the
* tests. */ if (pm.test_standard == 0 && pm.test_size == 0 && pm.test_transform == 0 && pm.ngammas == 0) { pm.test_standard = 1; pm.test_size = 1; pm.test_transform = 1; pm.ngammas = 3U; }
if (pm.ngammas > 0 && pm.test_gamma_threshold == 0 && pm.test_gamma_transform == 0 && pm.test_gamma_sbit == 0 && pm.test_gamma_strip16 == 0) { pm.test_gamma_threshold = 1; pm.test_gamma_transform = 1; pm.test_gamma_sbit = 1; pm.test_gamma_strip16 = 1; }
else if (pm.ngammas == 0) { /* Nothing to test so turn everything off: */ pm.test_gamma_threshold = 0; pm.test_gamma_transform = 0; pm.test_gamma_sbit = 0; pm.test_gamma_strip16 = 0; }
Try { /* Make useful base images */ make_transform_images(&pm.this);
/* Perform the standard and gamma tests. */ if (pm.test_standard) { perform_interlace_macro_validation(); perform_standard_test(&pm); perform_error_test(&pm); }
/* Various oddly sized images: */ if (pm.test_size) { make_size_images(&pm.this); perform_size_test(&pm); }
/* Combinatorial transforms: */ if (pm.test_transform) perform_transform_test(&pm);
if (pm.ngammas > 0) perform_gamma_test(&pm, pm.this.speed != 0, summary && !pm.this.speed); }
Catch(fault) { fprintf(stderr, "pngvalid: test aborted (probably failed in cleanup)\n"); if (!pm.this.verbose) { if (pm.this.error[0] != 0) fprintf(stderr, "pngvalid: first error: %s\n", pm.this.error);
fprintf(stderr, "pngvalid: run with -v to see what happened\n"); } exit(1); }
if (summary && !pm.this.speed) { printf("Results using %s point arithmetic %s\n",#if defined(PNG_FLOATING_ARITHMETIC_SUPPORTED) || PNG_LIBPNG_VER < 10500
"floating",#else
"fixed",#endif
(pm.this.nerrors || (pm.this.treat_warnings_as_errors && pm.this.nwarnings)) ? "(errors)" : (pm.this.nwarnings ? "(warnings)" : "(no errors or warnings)") ); printf("Allocated memory statistics (in bytes):\n" "\tread %lu maximum single, %lu peak, %lu total\n" "\twrite %lu maximum single, %lu peak, %lu total\n", (unsigned long)pm.this.read_memory_pool.max_max, (unsigned long)pm.this.read_memory_pool.max_limit, (unsigned long)pm.this.read_memory_pool.max_total, (unsigned long)pm.this.write_memory_pool.max_max, (unsigned long)pm.this.write_memory_pool.max_limit, (unsigned long)pm.this.write_memory_pool.max_total); }
/* Do this here to provoke memory corruption errors in memory not directly
* allocated by libpng - not a complete test, but better than nothing. */ store_delete(&pm.this);
/* Error exit if there are any errors, and maybe if there are any
* warnings. */ if (pm.this.nerrors || (pm.this.treat_warnings_as_errors && pm.this.nwarnings)) { if (!pm.this.verbose) fprintf(stderr, "pngvalid: %s\n", pm.this.error);
fprintf(stderr, "pngvalid: %d errors, %d warnings\n", pm.this.nerrors, pm.this.nwarnings);
exit(1); }
/* Success case. */ if (touch != NULL) { FILE *fsuccess = fopen(touch, "wt");
if (fsuccess != NULL) { int error = 0; fprintf(fsuccess, "PNG validation succeeded\n"); fflush(fsuccess); error = ferror(fsuccess);
if (fclose(fsuccess) || error) { fprintf(stderr, "%s: write failed\n", touch); exit(1); } } }
return 0;}
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