/* * jdmarker.c * * Copyright (C) 1991-1995, Thomas G. Lane. * This file is part of the Independent JPEG Group's software. * For conditions of distribution and use, see the accompanying README file. * * This file contains routines to decode JPEG datastream markers. * Most of the complexity arises from our desire to support input * suspension: if not all of the data for a marker is available, * we must exit back to the application. On resumption, we reprocess * the marker. */ #define JPEG_INTERNALS #include "jinclude.h" #include "jpeglib.h" //#pragma ident "@(#)jdmarker.cc 1.3 13:47:49 01/31/97" typedef enum { /* JPEG marker codes */ M_SOF0 = 0xc0, M_SOF1 = 0xc1, M_SOF2 = 0xc2, M_SOF3 = 0xc3, M_SOF5 = 0xc5, M_SOF6 = 0xc6, M_SOF7 = 0xc7, M_JPG = 0xc8, M_SOF9 = 0xc9, M_SOF10 = 0xca, M_SOF11 = 0xcb, M_SOF13 = 0xcd, M_SOF14 = 0xce, M_SOF15 = 0xcf, M_DHT = 0xc4, M_DAC = 0xcc, M_RST0 = 0xd0, M_RST1 = 0xd1, M_RST2 = 0xd2, M_RST3 = 0xd3, M_RST4 = 0xd4, M_RST5 = 0xd5, M_RST6 = 0xd6, M_RST7 = 0xd7, M_SOI = 0xd8, M_EOI = 0xd9, M_SOS = 0xda, M_DQT = 0xdb, M_DNL = 0xdc, M_DRI = 0xdd, M_DHP = 0xde, M_EXP = 0xdf, M_APP0 = 0xe0, M_APP1 = 0xe1, M_APP2 = 0xe2, M_APP3 = 0xe3, M_APP4 = 0xe4, M_APP5 = 0xe5, M_APP6 = 0xe6, M_APP7 = 0xe7, M_APP8 = 0xe8, M_APP9 = 0xe9, M_APP10 = 0xea, M_APP11 = 0xeb, M_APP12 = 0xec, M_APP13 = 0xed, M_APP14 = 0xee, M_APP15 = 0xef, M_JPG0 = 0xf0, M_JPG13 = 0xfd, M_COM = 0xfe, M_TEM = 0x01, M_ERROR = 0x100 } JPEG_MARKER; /* * Macros for fetching data from the data source module. * * At all times, cinfo->src->next_input_byte and ->bytes_in_buffer reflect * the current restart point; we update them only when we have reached a * suitable place to restart if a suspension occurs. */ /* Declare and initialize local copies of input pointer/count */ #define INPUT_VARS(cinfo) \ struct jpeg_source_mgr * datasrc = (cinfo)->src; \ const JOCTET * next_input_byte = datasrc->next_input_byte; \ size_t bytes_in_buffer = datasrc->bytes_in_buffer /* Unload the local copies --- do this only at a restart boundary */ #define INPUT_SYNC(cinfo) \ ( datasrc->next_input_byte = next_input_byte, \ datasrc->bytes_in_buffer = bytes_in_buffer ) /* Reload the local copies --- seldom used except in MAKE_BYTE_AVAIL */ #define INPUT_RELOAD(cinfo) \ ( next_input_byte = datasrc->next_input_byte, \ bytes_in_buffer = datasrc->bytes_in_buffer ) /* Internal macro for INPUT_BYTE and INPUT_2BYTES: make a byte available. * Note we do *not* do INPUT_SYNC before calling fill_input_buffer, * but we must reload the local copies after a successful fill. */ #define MAKE_BYTE_AVAIL(cinfo,action) \ if (bytes_in_buffer == 0) { \ if (! (*datasrc->fill_input_buffer) (cinfo)) \ { action; } \ INPUT_RELOAD(cinfo); \ } \ bytes_in_buffer--; /* Read a byte into variable V. * If must suspend, take the specified action (typically "return FALSE"). */ #define INPUT_BYTE(cinfo,V,action) \ MAKESTMT( MAKE_BYTE_AVAIL(cinfo,action); \ V = GETJOCTET(*next_input_byte++); ) /* As above, but read two bytes interpreted as an unsigned 16-bit integer. * V should be declared unsigned int or perhaps INT32. */ #define INPUT_2BYTES(cinfo,V,action) \ MAKESTMT( MAKE_BYTE_AVAIL(cinfo,action); \ V = ((unsigned int) GETJOCTET(*next_input_byte++)) << 8; \ MAKE_BYTE_AVAIL(cinfo,action); \ V += GETJOCTET(*next_input_byte++); ) /* * Routines to process JPEG markers. * * Entry condition: JPEG marker itself has been read and its code saved * in cinfo->unread_marker; input restart point is just after the marker. * * Exit: if return TRUE, have read and processed any parameters, and have * updated the restart point to point after the parameters. * If return FALSE, was forced to suspend before reaching end of * marker parameters; restart point has not been moved. Same routine * will be called again after application supplies more input data. * * This approach to suspension assumes that all of a marker's parameters can * fit into a single input bufferload. This should hold for "normal" * markers. Some COM/APPn markers might have large parameter segments, * but we use skip_input_data to get past those, and thereby put the problem * on the source manager's shoulders. * * Note that we don't bother to avoid duplicate trace messages if a * suspension occurs within marker parameters. Other side effects * require more care. */ LOCAL boolean get_soi (j_decompress_ptr cinfo) /* Process an SOI marker */ { int i; TRACEMS(cinfo, 1, JTRC_SOI); if (cinfo->marker->saw_SOI) ERREXIT(cinfo, JERR_SOI_DUPLICATE); /* Reset all parameters that are defined to be reset by SOI */ for (i = 0; i < NUM_ARITH_TBLS; i++) { cinfo->arith_dc_L[i] = 0; cinfo->arith_dc_U[i] = 1; cinfo->arith_ac_K[i] = 5; } cinfo->restart_interval = 0; /* Set initial assumptions for colorspace etc */ cinfo->jpeg_color_space = JCS_UNKNOWN; cinfo->CCIR601_sampling = FALSE; /* Assume non-CCIR sampling??? */ cinfo->saw_JFIF_marker = FALSE; cinfo->density_unit = 0; /* set default JFIF APP0 values */ cinfo->X_density = 1; cinfo->Y_density = 1; cinfo->saw_Adobe_marker = FALSE; cinfo->Adobe_transform = 0; cinfo->marker->saw_SOI = TRUE; return TRUE; } LOCAL boolean get_sof (j_decompress_ptr cinfo, boolean is_prog, boolean is_arith) /* Process a SOFn marker */ { INT32 length; int c, ci; jpeg_component_info * compptr; INPUT_VARS(cinfo); cinfo->progressive_mode = is_prog; cinfo->arith_code = is_arith; INPUT_2BYTES(cinfo, length, return FALSE); INPUT_BYTE(cinfo, cinfo->data_precision, return FALSE); INPUT_2BYTES(cinfo, cinfo->image_height, return FALSE); INPUT_2BYTES(cinfo, cinfo->image_width, return FALSE); INPUT_BYTE(cinfo, cinfo->num_components, return FALSE); length -= 8; TRACEMS4(cinfo, 1, JTRC_SOF, cinfo->unread_marker, (int) cinfo->image_width, (int) cinfo->image_height, cinfo->num_components); if (cinfo->marker->saw_SOF) ERREXIT(cinfo, JERR_SOF_DUPLICATE); /* We don't support files in which the image height is initially specified */ /* as 0 and is later redefined by DNL. As long as we have to check that, */ /* might as well have a general sanity check. */ if (cinfo->image_height <= 0 || cinfo->image_width <= 0 || cinfo->num_components <= 0) ERREXIT(cinfo, JERR_EMPTY_IMAGE); if (length != (cinfo->num_components * 3)) ERREXIT(cinfo, JERR_BAD_LENGTH); if (cinfo->comp_info == NULL) /* do only once, even if suspend */ cinfo->comp_info = (jpeg_component_info *) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, cinfo->num_components * SIZEOF(jpeg_component_info)); for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; ci++, compptr++) { compptr->component_index = ci; INPUT_BYTE(cinfo, compptr->component_id, return FALSE); INPUT_BYTE(cinfo, c, return FALSE); compptr->h_samp_factor = (c >> 4) & 15; compptr->v_samp_factor = (c ) & 15; INPUT_BYTE(cinfo, compptr->quant_tbl_no, return FALSE); TRACEMS4(cinfo, 1, JTRC_SOF_COMPONENT, compptr->component_id, compptr->h_samp_factor, compptr->v_samp_factor, compptr->quant_tbl_no); } cinfo->marker->saw_SOF = TRUE; INPUT_SYNC(cinfo); return TRUE; } LOCAL boolean get_sos (j_decompress_ptr cinfo) /* Process a SOS marker */ { INT32 length; int i, ci, n, c, cc; jpeg_component_info * compptr; INPUT_VARS(cinfo); if (! cinfo->marker->saw_SOF) ERREXIT(cinfo, JERR_SOS_NO_SOF); INPUT_2BYTES(cinfo, length, return FALSE); INPUT_BYTE(cinfo, n, return FALSE); /* Number of components */ if (length != (n * 2 + 6) || n < 1 || n > MAX_COMPS_IN_SCAN) ERREXIT(cinfo, JERR_BAD_LENGTH); TRACEMS1(cinfo, 1, JTRC_SOS, n); cinfo->comps_in_scan = n; /* Collect the component-spec parameters */ for (i = 0; i < n; i++) { INPUT_BYTE(cinfo, cc, return FALSE); INPUT_BYTE(cinfo, c, return FALSE); for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; ci++, compptr++) { if (cc == compptr->component_id) goto id_found; } ERREXIT1(cinfo, JERR_BAD_COMPONENT_ID, cc); id_found: cinfo->cur_comp_info[i] = compptr; compptr->dc_tbl_no = (c >> 4) & 15; compptr->ac_tbl_no = (c ) & 15; TRACEMS3(cinfo, 1, JTRC_SOS_COMPONENT, cc, compptr->dc_tbl_no, compptr->ac_tbl_no); } /* Collect the additional scan parameters Ss, Se, Ah/Al. */ INPUT_BYTE(cinfo, c, return FALSE); cinfo->Ss = c; INPUT_BYTE(cinfo, c, return FALSE); cinfo->Se = c; INPUT_BYTE(cinfo, c, return FALSE); cinfo->Ah = (c >> 4) & 15; cinfo->Al = (c ) & 15; TRACEMS4(cinfo, 1, JTRC_SOS_PARAMS, cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al); /* Prepare to scan data & restart markers */ cinfo->marker->next_restart_num = 0; /* Count another SOS marker */ cinfo->input_scan_number++; INPUT_SYNC(cinfo); return TRUE; } METHODDEF boolean get_app0 (j_decompress_ptr cinfo) /* Process an APP0 marker */ { #define JFIF_LEN 14 INT32 length; UINT8 b[JFIF_LEN]; int buffp; INPUT_VARS(cinfo); INPUT_2BYTES(cinfo, length, return FALSE); length -= 2; /* See if a JFIF APP0 marker is present */ if (length >= JFIF_LEN) { for (buffp = 0; buffp < JFIF_LEN; buffp++) INPUT_BYTE(cinfo, b[buffp], return FALSE); length -= JFIF_LEN; if (b[0]==0x4A && b[1]==0x46 && b[2]==0x49 && b[3]==0x46 && b[4]==0) { /* Found JFIF APP0 marker: check version */ /* Major version must be 1, anything else signals an incompatible change. * We used to treat this as an error, but now it's a nonfatal warning, * because some vendors misinterpreted the spec. * Minor version should be 0..2, but process anyway if newer. */ if (b[5] != 1) WARNMS2(cinfo, JWRN_JFIF_MAJOR, b[5], b[6]); else if (b[6] > 2) TRACEMS2(cinfo, 1, JTRC_JFIF_MINOR, b[5], b[6]); /* Save info */ cinfo->saw_JFIF_marker = TRUE; cinfo->density_unit = b[7]; cinfo->X_density = (b[8] << 8) + b[9]; cinfo->Y_density = (b[10] << 8) + b[11]; TRACEMS3(cinfo, 1, JTRC_JFIF, cinfo->X_density, cinfo->Y_density, cinfo->density_unit); if (b[12] | b[13]) TRACEMS2(cinfo, 1, JTRC_JFIF_THUMBNAIL, b[12], b[13]); if (length != ((INT32) b[12] * (INT32) b[13] * (INT32) 3)) TRACEMS1(cinfo, 1, JTRC_JFIF_BADTHUMBNAILSIZE, (int) length); } else { /* Start of APP0 does not match "JFIF" */ TRACEMS1(cinfo, 1, JTRC_APP0, (int) length + JFIF_LEN); } } else { /* Too short to be JFIF marker */ TRACEMS1(cinfo, 1, JTRC_APP0, (int) length); } INPUT_SYNC(cinfo); if (length > 0) /* skip any remaining data -- could be lots */ (*cinfo->src->skip_input_data) (cinfo, (long) length); return TRUE; } METHODDEF boolean get_app14 (j_decompress_ptr cinfo) /* Process an APP14 marker */ { #define ADOBE_LEN 12 INT32 length; UINT8 b[ADOBE_LEN]; int buffp; unsigned int version, flags0, flags1, transform; INPUT_VARS(cinfo); INPUT_2BYTES(cinfo, length, return FALSE); length -= 2; /* See if an Adobe APP14 marker is present */ if (length >= ADOBE_LEN) { for (buffp = 0; buffp < ADOBE_LEN; buffp++) INPUT_BYTE(cinfo, b[buffp], return FALSE); length -= ADOBE_LEN; if (b[0]==0x41 && b[1]==0x64 && b[2]==0x6F && b[3]==0x62 && b[4]==0x65) { /* Found Adobe APP14 marker */ version = (b[5] << 8) + b[6]; flags0 = (b[7] << 8) + b[8]; flags1 = (b[9] << 8) + b[10]; transform = b[11]; TRACEMS4(cinfo, 1, JTRC_ADOBE, version, flags0, flags1, transform); cinfo->saw_Adobe_marker = TRUE; cinfo->Adobe_transform = (UINT8) transform; } else { /* Start of APP14 does not match "Adobe" */ TRACEMS1(cinfo, 1, JTRC_APP14, (int) length + ADOBE_LEN); } } else { /* Too short to be Adobe marker */ TRACEMS1(cinfo, 1, JTRC_APP14, (int) length); } INPUT_SYNC(cinfo); if (length > 0) /* skip any remaining data -- could be lots */ (*cinfo->src->skip_input_data) (cinfo, (long) length); return TRUE; } LOCAL boolean get_dac (j_decompress_ptr cinfo) /* Process a DAC marker */ { INT32 length; int index, val; INPUT_VARS(cinfo); INPUT_2BYTES(cinfo, length, return FALSE); length -= 2; while (length > 0) { INPUT_BYTE(cinfo, index, return FALSE); INPUT_BYTE(cinfo, val, return FALSE); length -= 2; TRACEMS2(cinfo, 1, JTRC_DAC, index, val); if (index < 0 || index >= (2*NUM_ARITH_TBLS)) ERREXIT1(cinfo, JERR_DAC_INDEX, index); if (index >= NUM_ARITH_TBLS) { /* define AC table */ cinfo->arith_ac_K[index-NUM_ARITH_TBLS] = (UINT8) val; } else { /* define DC table */ cinfo->arith_dc_L[index] = (UINT8) (val & 0x0F); cinfo->arith_dc_U[index] = (UINT8) (val >> 4); if (cinfo->arith_dc_L[index] > cinfo->arith_dc_U[index]) ERREXIT1(cinfo, JERR_DAC_VALUE, val); } } INPUT_SYNC(cinfo); return TRUE; } LOCAL boolean get_dht (j_decompress_ptr cinfo) /* Process a DHT marker */ { INT32 length; UINT8 bits[17]; UINT8 huffval[256]; int i, index, count; JHUFF_TBL **htblptr; INPUT_VARS(cinfo); INPUT_2BYTES(cinfo, length, return FALSE); length -= 2; while (length > 0) { INPUT_BYTE(cinfo, index, return FALSE); TRACEMS1(cinfo, 1, JTRC_DHT, index); bits[0] = 0; count = 0; for (i = 1; i <= 16; i++) { INPUT_BYTE(cinfo, bits[i], return FALSE); count += bits[i]; } length -= 1 + 16; TRACEMS8(cinfo, 2, JTRC_HUFFBITS, bits[1], bits[2], bits[3], bits[4], bits[5], bits[6], bits[7], bits[8]); TRACEMS8(cinfo, 2, JTRC_HUFFBITS, bits[9], bits[10], bits[11], bits[12], bits[13], bits[14], bits[15], bits[16]); if (count > 256 || ((INT32) count) > length) ERREXIT(cinfo, JERR_DHT_COUNTS); for (i = 0; i < count; i++) INPUT_BYTE(cinfo, huffval[i], return FALSE); length -= count; if (index & 0x10) { /* AC table definition */ index -= 0x10; htblptr = &cinfo->ac_huff_tbl_ptrs[index]; } else { /* DC table definition */ htblptr = &cinfo->dc_huff_tbl_ptrs[index]; } if (index < 0 || index >= NUM_HUFF_TBLS) ERREXIT1(cinfo, JERR_DHT_INDEX, index); if (*htblptr == NULL) *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo); MEMCOPY((*htblptr)->bits, bits, SIZEOF((*htblptr)->bits)); MEMCOPY((*htblptr)->huffval, huffval, SIZEOF((*htblptr)->huffval)); } INPUT_SYNC(cinfo); return TRUE; } LOCAL boolean get_dqt (j_decompress_ptr cinfo) /* Process a DQT marker */ { INT32 length; int n, i, prec; unsigned int tmp; JQUANT_TBL *quant_ptr; INPUT_VARS(cinfo); INPUT_2BYTES(cinfo, length, return FALSE); length -= 2; while (length > 0) { INPUT_BYTE(cinfo, n, return FALSE); prec = n >> 4; n &= 0x0F; TRACEMS2(cinfo, 1, JTRC_DQT, n, prec); if (n >= NUM_QUANT_TBLS) ERREXIT1(cinfo, JERR_DQT_INDEX, n); if (cinfo->quant_tbl_ptrs[n] == NULL) cinfo->quant_tbl_ptrs[n] = jpeg_alloc_quant_table((j_common_ptr) cinfo); quant_ptr = cinfo->quant_tbl_ptrs[n]; for (i = 0; i < DCTSIZE2; i++) { if (prec) INPUT_2BYTES(cinfo, tmp, return FALSE); else INPUT_BYTE(cinfo, tmp, return FALSE); quant_ptr->quantval[i] = (UINT16) tmp; } for (i = 0; i < DCTSIZE2; i += 8) { TRACEMS8(cinfo, 2, JTRC_QUANTVALS, quant_ptr->quantval[i ], quant_ptr->quantval[i+1], quant_ptr->quantval[i+2], quant_ptr->quantval[i+3], quant_ptr->quantval[i+4], quant_ptr->quantval[i+5], quant_ptr->quantval[i+6], quant_ptr->quantval[i+7]); } length -= DCTSIZE2+1; if (prec) length -= DCTSIZE2; } INPUT_SYNC(cinfo); return TRUE; } LOCAL boolean get_dri (j_decompress_ptr cinfo) /* Process a DRI marker */ { INT32 length; unsigned int tmp; INPUT_VARS(cinfo); INPUT_2BYTES(cinfo, length, return FALSE); if (length != 4) ERREXIT(cinfo, JERR_BAD_LENGTH); INPUT_2BYTES(cinfo, tmp, return FALSE); TRACEMS1(cinfo, 1, JTRC_DRI, tmp); cinfo->restart_interval = tmp; INPUT_SYNC(cinfo); return TRUE; } METHODDEF boolean skip_variable (j_decompress_ptr cinfo) /* Skip over an unknown or uninteresting variable-length marker */ { INT32 length; INPUT_VARS(cinfo); INPUT_2BYTES(cinfo, length, return FALSE); TRACEMS2(cinfo, 1, JTRC_MISC_MARKER, cinfo->unread_marker, (int) length); INPUT_SYNC(cinfo); /* do before skip_input_data */ (*cinfo->src->skip_input_data) (cinfo, (long) length - 2L); return TRUE; } /* * Find the next JPEG marker, save it in cinfo->unread_marker. * Returns FALSE if had to suspend before reaching a marker; * in that case cinfo->unread_marker is unchanged. * * Note that the result might not be a valid marker code, * but it will never be 0 or FF. */ LOCAL boolean next_marker (j_decompress_ptr cinfo) { int c; INPUT_VARS(cinfo); for (;;) { INPUT_BYTE(cinfo, c, return FALSE); /* Skip any non-FF bytes. * This may look a bit inefficient, but it will not occur in a valid file. * We sync after each discarded byte so that a suspending data source * can discard the byte from its buffer. */ while (c != 0xFF) { cinfo->marker->discarded_bytes++; INPUT_SYNC(cinfo); INPUT_BYTE(cinfo, c, return FALSE); } /* This loop swallows any duplicate FF bytes. Extra FFs are legal as * pad bytes, so don't count them in discarded_bytes. We assume there * will not be so many consecutive FF bytes as to overflow a suspending * data source's input buffer. */ do { INPUT_BYTE(cinfo, c, return FALSE); } while (c == 0xFF); if (c != 0) break; /* found a valid marker, exit loop */ /* Reach here if we found a stuffed-zero data sequence (FF/00). * Discard it and loop back to try again. */ cinfo->marker->discarded_bytes += 2; INPUT_SYNC(cinfo); } if (cinfo->marker->discarded_bytes != 0) { WARNMS2(cinfo, JWRN_EXTRANEOUS_DATA, cinfo->marker->discarded_bytes, c); cinfo->marker->discarded_bytes = 0; } cinfo->unread_marker = c; INPUT_SYNC(cinfo); return TRUE; } LOCAL boolean first_marker (j_decompress_ptr cinfo) /* Like next_marker, but used to obtain the initial SOI marker. */ /* For this marker, we do not allow preceding garbage or fill; otherwise, * we might well scan an entire input file before realizing it ain't JPEG. * If an application wants to process non-JFIF files, it must seek to the * SOI before calling the JPEG library. */ { int c, c2; INPUT_VARS(cinfo); INPUT_BYTE(cinfo, c, return FALSE); INPUT_BYTE(cinfo, c2, return FALSE); if (c != 0xFF || c2 != (int) M_SOI) ERREXIT2(cinfo, JERR_NO_SOI, c, c2); cinfo->unread_marker = c2; INPUT_SYNC(cinfo); return TRUE; } /* * Read markers until SOS or EOI. * * Returns same codes as are defined for jpeg_consume_input: * JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI. */ METHODDEF int read_markers (j_decompress_ptr cinfo) { /* Outer loop repeats once for each marker. */ for (;;) { /* Collect the marker proper, unless we already did. */ /* NB: first_marker() enforces the requirement that SOI appear first. */ if (cinfo->unread_marker == 0) { if (! cinfo->marker->saw_SOI) { if (! first_marker(cinfo)) return JPEG_SUSPENDED; } else { if (! next_marker(cinfo)) return JPEG_SUSPENDED; } } /* At this point cinfo->unread_marker contains the marker code and the * input point is just past the marker proper, but before any parameters. * A suspension will cause us to return with this state still true. */ switch (cinfo->unread_marker) { case M_SOI: if (! get_soi(cinfo)) return JPEG_SUSPENDED; break; case M_SOF0: /* Baseline */ case M_SOF1: /* Extended sequential, Huffman */ if (! get_sof(cinfo, FALSE, FALSE)) return JPEG_SUSPENDED; break; case M_SOF2: /* Progressive, Huffman */ if (! get_sof(cinfo, TRUE, FALSE)) return JPEG_SUSPENDED; break; case M_SOF9: /* Extended sequential, arithmetic */ if (! get_sof(cinfo, FALSE, TRUE)) return JPEG_SUSPENDED; break; case M_SOF10: /* Progressive, arithmetic */ if (! get_sof(cinfo, TRUE, TRUE)) return JPEG_SUSPENDED; break; /* Currently unsupported SOFn types */ case M_SOF3: /* Lossless, Huffman */ case M_SOF5: /* Differential sequential, Huffman */ case M_SOF6: /* Differential progressive, Huffman */ case M_SOF7: /* Differential lossless, Huffman */ case M_JPG: /* Reserved for JPEG extensions */ case M_SOF11: /* Lossless, arithmetic */ case M_SOF13: /* Differential sequential, arithmetic */ case M_SOF14: /* Differential progressive, arithmetic */ case M_SOF15: /* Differential lossless, arithmetic */ ERREXIT1(cinfo, JERR_SOF_UNSUPPORTED, cinfo->unread_marker); break; case M_SOS: if (! get_sos(cinfo)) return JPEG_SUSPENDED; cinfo->unread_marker = 0; /* processed the marker */ return JPEG_REACHED_SOS; case M_EOI: TRACEMS(cinfo, 1, JTRC_EOI); cinfo->unread_marker = 0; /* processed the marker */ return JPEG_REACHED_EOI; case M_DAC: if (! get_dac(cinfo)) return JPEG_SUSPENDED; break; case M_DHT: if (! get_dht(cinfo)) return JPEG_SUSPENDED; break; case M_DQT: if (! get_dqt(cinfo)) return JPEG_SUSPENDED; break; case M_DRI: if (! get_dri(cinfo)) return JPEG_SUSPENDED; break; case M_APP0: case M_APP1: case M_APP2: case M_APP3: case M_APP4: case M_APP5: case M_APP6: case M_APP7: case M_APP8: case M_APP9: case M_APP10: case M_APP11: case M_APP12: case M_APP13: case M_APP14: case M_APP15: if (! (*cinfo->marker->process_APPn[cinfo->unread_marker - (int) M_APP0]) (cinfo)) return JPEG_SUSPENDED; break; case M_COM: if (! (*cinfo->marker->process_COM) (cinfo)) return JPEG_SUSPENDED; break; case M_RST0: /* these are all parameterless */ case M_RST1: case M_RST2: case M_RST3: case M_RST4: case M_RST5: case M_RST6: case M_RST7: case M_TEM: TRACEMS1(cinfo, 1, JTRC_PARMLESS_MARKER, cinfo->unread_marker); break; case M_DNL: /* Ignore DNL ... perhaps the wrong thing */ if (! skip_variable(cinfo)) return JPEG_SUSPENDED; break; default: /* must be DHP, EXP, JPGn, or RESn */ /* For now, we treat the reserved markers as fatal errors since they are * likely to be used to signal incompatible JPEG Part 3 extensions. * Once the JPEG 3 version-number marker is well defined, this code * ought to change! */ ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, cinfo->unread_marker); break; } /* Successfully processed marker, so reset state variable */ cinfo->unread_marker = 0; } /* end loop */ } /* * Read a restart marker, which is expected to appear next in the datastream; * if the marker is not there, take appropriate recovery action. * Returns FALSE if suspension is required. * * This is called by the entropy decoder after it has read an appropriate * number of MCUs. cinfo->unread_marker may be nonzero if the entropy decoder * has already read a marker from the data source. Under normal conditions * cinfo->unread_marker will be reset to 0 before returning; if not reset, * it holds a marker which the decoder will be unable to read past. */ METHODDEF boolean read_restart_marker (j_decompress_ptr cinfo) { /* Obtain a marker unless we already did. */ /* Note that next_marker will complain if it skips any data. */ if (cinfo->unread_marker == 0) { if (! next_marker(cinfo)) return FALSE; } if (cinfo->unread_marker == ((int) M_RST0 + cinfo->marker->next_restart_num)) { /* Normal case --- swallow the marker and let entropy decoder continue */ TRACEMS1(cinfo, 2, JTRC_RST, cinfo->marker->next_restart_num); cinfo->unread_marker = 0; } else { /* Uh-oh, the restart markers have been messed up. */ /* Let the data source manager determine how to resync. */ if (! (*cinfo->src->resync_to_restart) (cinfo, cinfo->marker->next_restart_num)) return FALSE; } /* Update next-restart state */ cinfo->marker->next_restart_num = (cinfo->marker->next_restart_num + 1) & 7; return TRUE; } /* * This is the default resync_to_restart method for data source managers * to use if they don't have any better approach. Some data source managers * may be able to back up, or may have additional knowledge about the data * which permits a more intelligent recovery strategy; such managers would * presumably supply their own resync method. * * read_restart_marker calls resync_to_restart if it finds a marker other than * the restart marker it was expecting. (This code is *not* used unless * a nonzero restart interval has been declared.) cinfo->unread_marker is * the marker code actually found (might be anything, except 0 or FF). * The desired restart marker number (0..7) is passed as a parameter. * This routine is supposed to apply whatever error recovery strategy seems * appropriate in order to position the input stream to the next data segment. * Note that cinfo->unread_marker is treated as a marker appearing before * the current data-source input point; usually it should be reset to zero * before returning. * Returns FALSE if suspension is required. * * This implementation is substantially constrained by wanting to treat the * input as a data stream; this means we can't back up. Therefore, we have * only the following actions to work with: * 1. Simply discard the marker and let the entropy decoder resume at next * byte of file. * 2. Read forward until we find another marker, discarding intervening * data. (In theory we could look ahead within the current bufferload, * without having to discard data if we don't find the desired marker. * This idea is not implemented here, in part because it makes behavior * dependent on buffer size and chance buffer-boundary positions.) * 3. Leave the marker unread (by failing to zero cinfo->unread_marker). * This will cause the entropy decoder to process an empty data segment, * inserting dummy zeroes, and then we will reprocess the marker. * * #2 is appropriate if we think the desired marker lies ahead, while #3 is * appropriate if the found marker is a future restart marker (indicating * that we have missed the desired restart marker, probably because it got * corrupted). * We apply #2 or #3 if the found marker is a restart marker no more than * two counts behind or ahead of the expected one. We also apply #2 if the * found marker is not a legal JPEG marker code (it's certainly bogus data). * If the found marker is a restart marker more than 2 counts away, we do #1 * (too much risk that the marker is erroneous; with luck we will be able to * resync at some future point). * For any valid non-restart JPEG marker, we apply #3. This keeps us from * overrunning the end of a scan. An implementation limited to single-scan * files might find it better to apply #2 for markers other than EOI, since * any other marker would have to be bogus data in that case. */ GLOBAL boolean jpeg_resync_to_restart (j_decompress_ptr cinfo, int desired) { int marker = cinfo->unread_marker; int action = 1; /* Always put up a warning. */ WARNMS2(cinfo, JWRN_MUST_RESYNC, marker, desired); /* Outer loop handles repeated decision after scanning forward. */ for (;;) { if (marker < (int) M_SOF0) action = 2; /* invalid marker */ else if (marker < (int) M_RST0 || marker > (int) M_RST7) action = 3; /* valid non-restart marker */ else { if (marker == ((int) M_RST0 + ((desired+1) & 7)) || marker == ((int) M_RST0 + ((desired+2) & 7))) action = 3; /* one of the next two expected restarts */ else if (marker == ((int) M_RST0 + ((desired-1) & 7)) || marker == ((int) M_RST0 + ((desired-2) & 7))) action = 2; /* a prior restart, so advance */ else action = 1; /* desired restart or too far away */ } TRACEMS2(cinfo, 4, JTRC_RECOVERY_ACTION, marker, action); switch (action) { case 1: /* Discard marker and let entropy decoder resume processing. */ cinfo->unread_marker = 0; return TRUE; case 2: /* Scan to the next marker, and repeat the decision loop. */ if (! next_marker(cinfo)) return FALSE; marker = cinfo->unread_marker; break; case 3: /* Return without advancing past this marker. */ /* Entropy decoder will be forced to process an empty segment. */ return TRUE; } } /* end loop */ } /* * Reset marker processing state to begin a fresh datastream. */ METHODDEF void reset_marker_reader (j_decompress_ptr cinfo) { cinfo->comp_info = NULL; /* until allocated by get_sof */ cinfo->input_scan_number = 0; /* no SOS seen yet */ cinfo->unread_marker = 0; /* no pending marker */ cinfo->marker->saw_SOI = FALSE; /* set internal state too */ cinfo->marker->saw_SOF = FALSE; cinfo->marker->discarded_bytes = 0; } /* * Initialize the marker reader module. * This is called only once, when the decompression object is created. */ GLOBAL void jinit_marker_reader (j_decompress_ptr cinfo) { int i; /* Create subobject in permanent pool */ cinfo->marker = (struct jpeg_marker_reader *) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT, SIZEOF(struct jpeg_marker_reader)); /* Initialize method pointers */ cinfo->marker->reset_marker_reader = reset_marker_reader; cinfo->marker->read_markers = read_markers; cinfo->marker->read_restart_marker = read_restart_marker; cinfo->marker->process_COM = skip_variable; for (i = 0; i < 16; i++) cinfo->marker->process_APPn[i] = skip_variable; cinfo->marker->process_APPn[0] = get_app0; cinfo->marker->process_APPn[14] = get_app14; /* Reset marker processing state */ reset_marker_reader(cinfo); }