mirror of https://github.com/tongzx/nt5src
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
281 lines
9.5 KiB
281 lines
9.5 KiB
/***
|
|
*ftell.c - get current file position
|
|
*
|
|
* Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.
|
|
*
|
|
*Purpose:
|
|
* defines ftell() - find current current position of file pointer
|
|
*
|
|
*Revision History:
|
|
* 09-02-83 RN initial version
|
|
* ??-??-?? TC added code to allow variable buffer sizes
|
|
* 05-22-86 TC added code to seek to send if last operation was a
|
|
* write and append mode specified
|
|
* 11-20-86 SKS do not seek to end of file in append mode
|
|
* 12-01-86 SKS fix off-by-1 problem in text mode when last byte in
|
|
* buffer was a '\r', and it was followed by a '\n'. Since
|
|
* the \n was pushed back and the \r was discarded, we
|
|
* must adjust the computed position for the \r.
|
|
* 02-09-87 JCR Added errno set code (if flag (_IORW not set)
|
|
* 09-09-87 JCR Optimized to eliminate two lseek() calls in binary mode.
|
|
* 09-28-87 JCR Corrected _iob2 indexing (now uses _iob_index() macro).
|
|
* 11-04-87 JCR Multi-thread version
|
|
* 12-11-87 JCR Added "_LOAD_DS" to declaration
|
|
* 01-13-88 JCR Removed unnecessary calls to mthread fileno/feof/ferror
|
|
* 05-27-88 PHG Merged DLL and normal versions
|
|
* 06-06-88 JCR Use _iob2_ macro instead of _iob_index
|
|
* 06-15-88 JCR Near reference to _iob[] entries; improve REG variables
|
|
* 07-27-88 JCR Changed some variables from int to unsigned (bug fix)
|
|
* 08-25-88 GJF Don't use FP_OFF() macro for the 386
|
|
* 12-05-88 JCR Added _IOCTRLZ support (fixes bug pertaining to ^Z at
|
|
* eof)
|
|
* 08-17-89 GJF Cleanup, now specific to OS/2 2.0 (i.e., 386 flat
|
|
* model), also fixed copyright
|
|
* 02-15-90 GJF _iob[], _iob2[] merge. Also, fixed copyright and
|
|
* indents.
|
|
* 03-19-90 GJF Made calling type _CALLTYPE1, added #include
|
|
* <cruntime.h> and removed #include <register.h>.
|
|
* 07-23-90 SBM Replaced <assertm.h> by <assert.h>
|
|
* 10-02-90 GJF New-style function declarators.
|
|
* 01-21-91 GJF ANSI naming.
|
|
* 03-27-92 DJM POSIX support.
|
|
* 08-26-92 GJF Include unistd.h for POSIX build.
|
|
* 09-01-92 GJF Fixed POSIX support (was returning -1 for all except
|
|
* read-write streams).
|
|
* 04-06-93 SKS Replace _CRTAPI* with __cdecl
|
|
* 06-29-93 GJF Fixed bug related to variable buffer sizing (Cuda
|
|
* #5456).
|
|
* 09-06-94 CFW Replace MTHREAD with _MT.
|
|
* 02-06-94 CFW assert -> _ASSERTE.
|
|
* 02-20-95 GJF Merged in Mac version.
|
|
* 03-07-95 GJF _[un]lock_str macros now take FILE * arg.
|
|
* 06-12-95 GJF Replaced _osfile[] with _osfile() (macro referencing
|
|
* field in ioinfo struct).
|
|
* 02-27-98 RKP Add 64 bit support.
|
|
* 03-02-98 GJF Exception-safe locking.
|
|
* 05-17-99 PML Remove all Macintosh support.
|
|
*
|
|
*******************************************************************************/
|
|
|
|
#include <cruntime.h>
|
|
#include <stdio.h>
|
|
#include <file2.h>
|
|
#include <dbgint.h>
|
|
#include <errno.h>
|
|
#ifdef _POSIX_
|
|
#include <unistd.h>
|
|
#else
|
|
#include <msdos.h>
|
|
#endif
|
|
#include <stddef.h>
|
|
#include <io.h>
|
|
#include <internal.h>
|
|
#ifndef _POSIX_
|
|
#include <mtdll.h>
|
|
#endif
|
|
|
|
/***
|
|
*long ftell(stream) - query stream file pointer
|
|
*
|
|
*Purpose:
|
|
* Find out what stream's position is. coordinate with buffering; adjust
|
|
* backward for read-ahead and forward for write-behind. This is NOT
|
|
* equivalent to fseek(stream,0L,1), because fseek will remove an ungetc,
|
|
* may flush buffers, etc.
|
|
*
|
|
*Entry:
|
|
* FILE *stream - stream to query for position
|
|
*
|
|
*Exit:
|
|
* return present file position if succeeds
|
|
* returns -1L and sets errno if fails
|
|
*
|
|
*Exceptions:
|
|
*
|
|
*******************************************************************************/
|
|
|
|
#ifdef _MT /* multi-thread; define both ftell() and _lk_ftell() */
|
|
|
|
long __cdecl ftell (
|
|
FILE *stream
|
|
)
|
|
{
|
|
long retval;
|
|
|
|
_ASSERTE(stream != NULL);
|
|
|
|
_lock_str(stream);
|
|
|
|
__try {
|
|
retval = _ftell_lk (stream);
|
|
}
|
|
__finally {
|
|
_unlock_str(stream);
|
|
}
|
|
|
|
return(retval);
|
|
}
|
|
|
|
|
|
/***
|
|
*_ftell_lk() - Ftell() core routine (assumes stream is locked).
|
|
*
|
|
*Purpose:
|
|
* Core ftell() routine; assumes caller has aquired stream lock).
|
|
*
|
|
* [See ftell() above for more info.]
|
|
*
|
|
*Entry: [See ftell()]
|
|
*
|
|
*Exit: [See ftell()]
|
|
*
|
|
*Exceptions:
|
|
*
|
|
*******************************************************************************/
|
|
|
|
long __cdecl _ftell_lk (
|
|
|
|
#else /* non multi-thread; define only ftell() */
|
|
|
|
long __cdecl ftell (
|
|
|
|
#endif /* rejoin common code */
|
|
|
|
FILE *str
|
|
)
|
|
{
|
|
REG1 FILE *stream;
|
|
unsigned int offset;
|
|
long filepos;
|
|
#if !defined(_POSIX_)
|
|
REG2 char *p;
|
|
char *max;
|
|
#endif
|
|
int fd;
|
|
unsigned int rdcnt;
|
|
|
|
_ASSERTE(str != NULL);
|
|
|
|
/* Init stream pointer and file descriptor */
|
|
stream = str;
|
|
#ifdef _POSIX_
|
|
fd = fileno(stream);
|
|
#else
|
|
fd = _fileno(stream);
|
|
#endif
|
|
|
|
if (stream->_cnt < 0)
|
|
stream->_cnt = 0;
|
|
|
|
#ifdef _POSIX_
|
|
if ((filepos = lseek(fd, 0L, SEEK_CUR)) < 0L)
|
|
#else
|
|
if ((filepos = _lseek(fd, 0L, SEEK_CUR)) < 0L)
|
|
#endif
|
|
return(-1L);
|
|
|
|
if (!bigbuf(stream)) /* _IONBF or no buffering designated */
|
|
return(filepos - stream->_cnt);
|
|
|
|
offset = (unsigned)(stream->_ptr - stream->_base);
|
|
|
|
#ifndef _POSIX_
|
|
if (stream->_flag & (_IOWRT|_IOREAD)) {
|
|
if (_osfile(fd) & FTEXT)
|
|
for (p = stream->_base; p < stream->_ptr; p++)
|
|
if (*p == '\n') /* adjust for '\r' */
|
|
offset++;
|
|
}
|
|
else if (!(stream->_flag & _IORW)) {
|
|
errno=EINVAL;
|
|
return(-1L);
|
|
}
|
|
#endif
|
|
|
|
if (filepos == 0L)
|
|
return((long)offset);
|
|
|
|
if (stream->_flag & _IOREAD) /* go to preceding sector */
|
|
|
|
if (stream->_cnt == 0) /* filepos holds correct location */
|
|
offset = 0;
|
|
|
|
else {
|
|
|
|
/* Subtract out the number of unread bytes left in the buffer.
|
|
[We can't simply use _iob[]._bufsiz because the last read
|
|
may have hit EOF and, thus, the buffer was not completely
|
|
filled.] */
|
|
|
|
rdcnt = stream->_cnt + (unsigned)(stream->_ptr - stream->_base);
|
|
|
|
#if !defined(_POSIX_)
|
|
/* If text mode, adjust for the cr/lf substitution. If binary
|
|
mode, we're outta here. */
|
|
if (_osfile(fd) & FTEXT) {
|
|
/* (1) If we're not at eof, simply copy _bufsiz onto rdcnt
|
|
to get the # of untranslated chars read. (2) If we're at
|
|
eof, we must look through the buffer expanding the '\n'
|
|
chars one at a time. */
|
|
|
|
/* [NOTE: Performance issue -- it is faster to do the two
|
|
_lseek() calls than to blindly go through and expand the
|
|
'\n' chars regardless of whether we're at eof or not.] */
|
|
|
|
if (_lseek(fd, 0L, 2) == filepos) {
|
|
|
|
max = stream->_base + rdcnt;
|
|
for (p = stream->_base; p < max; p++)
|
|
if (*p == '\n')
|
|
/* adjust for '\r' */
|
|
rdcnt++;
|
|
|
|
/* If last byte was ^Z, the lowio read didn't tell us
|
|
about it. Check flag and bump count, if necessary. */
|
|
|
|
if (stream->_flag & _IOCTRLZ)
|
|
++rdcnt;
|
|
}
|
|
|
|
else {
|
|
|
|
_lseek(fd, filepos, 0);
|
|
|
|
/* We want to set rdcnt to the number of bytes
|
|
originally read into the stream buffer (before
|
|
crlf->lf translation). In most cases, this will
|
|
just be _bufsiz. However, the buffer size may have
|
|
been changed, due to fseek optimization, at the
|
|
END of the last _filbuf call. */
|
|
|
|
if ( (rdcnt <= _SMALL_BUFSIZ) &&
|
|
(stream->_flag & _IOMYBUF) &&
|
|
!(stream->_flag & _IOSETVBUF) )
|
|
{
|
|
/* The translated contents of the buffer is small
|
|
and we are not at eof. The buffer size must have
|
|
been set to _SMALL_BUFSIZ during the last
|
|
_filbuf call. */
|
|
|
|
rdcnt = _SMALL_BUFSIZ;
|
|
}
|
|
else
|
|
rdcnt = stream->_bufsiz;
|
|
|
|
/* If first byte in untranslated buffer was a '\n',
|
|
assume it was preceeded by a '\r' which was
|
|
discarded by the previous read operation and count
|
|
the '\n'. */
|
|
if (_osfile(fd) & FCRLF)
|
|
++rdcnt;
|
|
}
|
|
|
|
} /* end if FTEXT */
|
|
#endif
|
|
|
|
filepos -= (long)rdcnt;
|
|
|
|
} /* end else stream->_cnt != 0 */
|
|
|
|
return(filepos + (long)offset);
|
|
}
|