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/***
*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);}
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