/***
*ftell.c - get current file position
*
* Copyright (c) 1985-1992, 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).
*
*******************************************************************************/
#include <cruntime.h>
#include <stdio.h>
#include <file2.h>
#include <assert.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 <os2dll.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 MTHREAD /* multi-thread; define both ftell() and _lk_ftell() */
long _CALLTYPE1 ftell (
FILE *stream
)
{
long retval;
#ifdef MTHREAD
int index;
#endif
assert(stream != NULL);
#ifdef MTHREAD
index = _iob_index(stream);
#endif
_lock_str(index);
retval = _ftell_lk (stream);
_unlock_str(index);
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 _CALLTYPE1 _ftell_lk (
#else /* non multi-thread; define only ftell() */
long _CALLTYPE1 ftell (
#endif /* rejoin common code */
FILE *str
)
{
REG1 FILE *stream;
unsigned int offset;
long filepos;
#ifndef _POSIX_
REG2 char *p;
char *max;
#endif
int fd;
unsigned int rdcnt;
assert(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 = 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 + (stream->_ptr - stream->_base);
#ifndef _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);
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 /* !_POSIX_ */
filepos -= (long)rdcnt;
} /* end else stream->_cnt != 0 */
return(filepos + (long)offset);
}
