229 lines
7.9 KiB
C
229 lines
7.9 KiB
C
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/***
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*ftelli64.c - get current file position
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*
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* Copyright (c) 1994-2001, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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* defines _ftelli64() - find current current position of file pointer
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*
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*Revision History:
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* 12-22-94 GJF Module created. Derived from ftell.c
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* 02-06-94 CFW assert -> _ASSERTE.
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* 03-07-95 GJF _[un]lock_str macros now take FILE * arg.
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* 06-23-95 GJF Replaced _osfile[] with _osfile() (macro referencing
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* field in ioinfo struct).
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* 03-02-98 GJF Exception-safe locking.
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* 03-04-98 RKP Added 64 bit support.
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*
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*******************************************************************************/
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#include <cruntime.h>
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#include <stdio.h>
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#include <file2.h>
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#include <dbgint.h>
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#include <errno.h>
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#include <msdos.h>
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#include <stddef.h>
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#include <io.h>
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#include <internal.h>
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#include <mtdll.h>
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/***
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*__int64 _ftelli64(stream) - query stream file pointer
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*
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*Purpose:
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* Find out what stream's position is. coordinate with buffering; adjust
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* backward for read-ahead and forward for write-behind. This is NOT
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* equivalent to fseek(stream,0L,1), because fseek will remove an ungetc,
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* may flush buffers, etc.
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*
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*Entry:
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* FILE *stream - stream to query for position
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*
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*Exit:
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* return present file position if succeeds
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* returns -1i64 and sets errno if fails
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*
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*Exceptions:
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*
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*******************************************************************************/
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#ifdef _MT
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__int64 __cdecl _ftelli64 (
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FILE *stream
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)
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{
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__int64 retval;
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_ASSERTE(stream != NULL);
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_lock_str(stream);
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__try {
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retval = _ftelli64_lk (stream);
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}
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__finally {
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_unlock_str(stream);
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}
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return(retval);
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}
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/***
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*_ftelli64_lk() - _ftelli64() core routine (assumes stream is locked).
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*
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*Purpose:
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* Core _ftelli64() routine (assumes caller has aquired stream lock).
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*
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*Entry:
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*
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*Exit:
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*
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*Exceptions:
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*
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*******************************************************************************/
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__int64 __cdecl _ftelli64_lk (
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#else /* mdef _MT */
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__int64 __cdecl _ftelli64 (
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#endif /* _MT */
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FILE *str
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)
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{
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REG1 FILE *stream;
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size_t offset;
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__int64 filepos;
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REG2 char *p;
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char *max;
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int fd;
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size_t rdcnt;
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_ASSERTE(str != NULL);
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/* Init stream pointer and file descriptor */
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stream = str;
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fd = _fileno(stream);
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if (stream->_cnt < 0)
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stream->_cnt = 0;
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if ((filepos = _lseeki64(fd, 0i64, SEEK_CUR)) < 0L)
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return(-1i64);
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if (!bigbuf(stream)) /* _IONBF or no buffering designated */
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return(filepos - stream->_cnt);
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offset = (size_t)(stream->_ptr - stream->_base);
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if (stream->_flag & (_IOWRT|_IOREAD)) {
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if (_osfile(fd) & FTEXT)
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for (p = stream->_base; p < stream->_ptr; p++)
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if (*p == '\n') /* adjust for '\r' */
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offset++;
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}
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else if (!(stream->_flag & _IORW)) {
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errno=EINVAL;
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return(-1i64);
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}
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if (filepos == 0i64)
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return((__int64)offset);
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if (stream->_flag & _IOREAD) /* go to preceding sector */
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if (stream->_cnt == 0) /* filepos holds correct location */
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offset = 0;
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else {
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/* Subtract out the number of unread bytes left in the
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buffer. [We can't simply use _iob[]._bufsiz because
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the last read may have hit EOF and, thus, the buffer
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was not completely filled.] */
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rdcnt = stream->_cnt + (size_t)(stream->_ptr - stream->_base);
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/* If text mode, adjust for the cr/lf substitution. If
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binary mode, we're outta here. */
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if (_osfile(fd) & FTEXT) {
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/* (1) If we're not at eof, simply copy _bufsiz
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onto rdcnt to get the # of untranslated
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chars read. (2) If we're at eof, we must
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look through the buffer expanding the '\n'
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chars one at a time. */
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/* [NOTE: Performance issue -- it is faster to
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do the two _lseek() calls than to blindly go
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through and expand the '\n' chars regardless
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of whether we're at eof or not.] */
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if (_lseeki64(fd, 0i64, SEEK_END) == filepos) {
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max = stream->_base + rdcnt;
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for (p = stream->_base; p < max; p++)
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if (*p == '\n')
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/* adjust for '\r' */
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rdcnt++;
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/* If last byte was ^Z, the lowio read
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didn't tell us about it. Check flag
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and bump count, if necessary. */
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if (stream->_flag & _IOCTRLZ)
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++rdcnt;
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}
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else {
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_lseeki64(fd, filepos, SEEK_SET);
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/* We want to set rdcnt to the number
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of bytes originally read into the
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stream buffer (before crlf->lf
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translation). In most cases, this
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will just be _bufsiz. However, the
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buffer size may have been changed,
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due to fseek optimization, at the
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END of the last _filbuf call. */
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if ( (rdcnt <= _SMALL_BUFSIZ) &&
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(stream->_flag & _IOMYBUF) &&
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!(stream->_flag & _IOSETVBUF) )
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{
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/* The translated contents of
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the buffer is small and we
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are not at eof. The buffer
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size must have been set to
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_SMALL_BUFSIZ during the
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last _filbuf call. */
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rdcnt = _SMALL_BUFSIZ;
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}
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else
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rdcnt = stream->_bufsiz;
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/* If first byte in untranslated buffer
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was a '\n', assume it was preceeded
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by a '\r' which was discarded by the
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previous read operation and count
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the '\n'. */
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if (_osfile(fd) & FCRLF)
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++rdcnt;
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}
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} /* end if FTEXT */
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filepos -= (__int64)rdcnt;
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} /* end else stream->_cnt != 0 */
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return(filepos + (__int64)offset);
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}
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