156 lines
3.9 KiB
C
156 lines
3.9 KiB
C
|
/***
|
||
|
|
*fseeki64.c - reposition file pointer on a stream
|
||
|
|
*
|
||
|
|
* Copyright (c) 1994-2001, Microsoft Corporation. All rights reserved.
|
||
|
|
*
|
||
|
|
*Purpose:
|
||
|
|
* defines _fseeki64() - move the file pointer to new place in file
|
||
|
|
*
|
||
|
|
*Revision History:
|
||
|
|
* 12-15-94 GJF Module created. Derived from fseek.c.
|
||
|
|
* 02-06-94 CFW assert -> _ASSERTE.
|
||
|
|
* 03-07-95 GJF _[un]lock_str macros now take FILE * arg.
|
||
|
|
* 03-02-98 GJF Exception-safe locking.
|
||
|
|
*
|
||
|
|
*******************************************************************************/
|
||
|
|
|
||
|
|
#include <cruntime.h>
|
||
|
|
#include <stdio.h>
|
||
|
|
#include <file2.h>
|
||
|
|
#include <dbgint.h>
|
||
|
|
#include <msdos.h>
|
||
|
|
#include <errno.h>
|
||
|
|
#include <malloc.h>
|
||
|
|
#include <io.h>
|
||
|
|
#include <stddef.h>
|
||
|
|
#include <internal.h>
|
||
|
|
#include <mtdll.h>
|
||
|
|
|
||
|
|
/***
|
||
|
|
*int _fseeki64(stream, offset, whence) - reposition file pointer
|
||
|
|
*
|
||
|
|
*Purpose:
|
||
|
|
*
|
||
|
|
* Reposition file pointer to the desired location. The new location
|
||
|
|
* is calculated as follows:
|
||
|
|
* { whence=0, beginning of file }
|
||
|
|
* <offset> bytes + { whence=1, current position }
|
||
|
|
* { whence=2, end of file }
|
||
|
|
*
|
||
|
|
* Be careful to coordinate with buffering.
|
||
|
|
*
|
||
|
|
*Entry:
|
||
|
|
* FILE *stream - file to reposition file pointer on
|
||
|
|
* _int64 offset - offset to seek to
|
||
|
|
* int whence - origin offset is measured from (0=beg, 1=current pos,
|
||
|
|
* 2=end)
|
||
|
|
*
|
||
|
|
*Exit:
|
||
|
|
* returns 0 if succeeds
|
||
|
|
* returns -1 and sets errno if fails
|
||
|
|
* fields of FILE struct will be changed
|
||
|
|
*
|
||
|
|
*Exceptions:
|
||
|
|
*
|
||
|
|
*******************************************************************************/
|
||
|
|
|
||
|
|
#ifdef _MT /* multi-thread; define both fseek() and _lk_fseek() */
|
||
|
|
|
||
|
|
int __cdecl _fseeki64 (
|
||
|
|
FILE *stream,
|
||
|
|
__int64 offset,
|
||
|
|
int whence
|
||
|
|
)
|
||
|
|
{
|
||
|
|
int retval;
|
||
|
|
|
||
|
|
_ASSERTE(stream != NULL);
|
||
|
|
|
||
|
|
_lock_str(stream);
|
||
|
|
|
||
|
|
__try {
|
||
|
|
retval = _fseeki64_lk (stream, offset, whence);
|
||
|
|
}
|
||
|
|
__finally {
|
||
|
|
_unlock_str(stream);
|
||
|
|
}
|
||
|
|
|
||
|
|
return(retval);
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
/***
|
||
|
|
*_fseeki64_lk() - Core _fseeki64() routine (stream is locked)
|
||
|
|
*
|
||
|
|
*Purpose:
|
||
|
|
* Core _fseeki64() routine; assumes that caller has the stream locked.
|
||
|
|
*
|
||
|
|
*Entry:
|
||
|
|
*
|
||
|
|
*Exit:
|
||
|
|
*
|
||
|
|
*Exceptions:
|
||
|
|
*
|
||
|
|
*******************************************************************************/
|
||
|
|
|
||
|
|
int __cdecl _fseeki64_lk (
|
||
|
|
|
||
|
|
#else /* non multi-thread; just define fseek() */
|
||
|
|
|
||
|
|
int __cdecl _fseeki64 (
|
||
|
|
|
||
|
|
#endif /* rejoin common code */
|
||
|
|
|
||
|
|
FILE *str,
|
||
|
|
__int64 offset,
|
||
|
|
int whence
|
||
|
|
)
|
||
|
|
{
|
||
|
|
|
||
|
|
|
||
|
|
REG1 FILE *stream;
|
||
|
|
|
||
|
|
_ASSERTE(str != NULL);
|
||
|
|
|
||
|
|
/* Init stream pointer */
|
||
|
|
stream = str;
|
||
|
|
|
||
|
|
if ( !inuse(stream) || ((whence != SEEK_SET) && (whence != SEEK_CUR) &&
|
||
|
|
(whence != SEEK_END)) ) {
|
||
|
|
errno=EINVAL;
|
||
|
|
return(-1);
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Clear EOF flag */
|
||
|
|
|
||
|
|
stream->_flag &= ~_IOEOF;
|
||
|
|
|
||
|
|
/* If seeking relative to current location, then convert to
|
||
|
|
a seek relative to beginning of file. This accounts for
|
||
|
|
buffering, etc. by letting fseek() tell us where we are. */
|
||
|
|
|
||
|
|
if (whence == SEEK_CUR) {
|
||
|
|
offset += _ftelli64_lk(stream);
|
||
|
|
whence = SEEK_SET;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Flush buffer as necessary */
|
||
|
|
|
||
|
|
_flush(stream);
|
||
|
|
|
||
|
|
/* If file opened for read/write, clear flags since we don't know
|
||
|
|
what the user is going to do next. If the file was opened for
|
||
|
|
read access only, decrease _bufsiz so that the next _filbuf
|
||
|
|
won't cost quite so much */
|
||
|
|
|
||
|
|
if (stream->_flag & _IORW)
|
||
|
|
stream->_flag &= ~(_IOWRT|_IOREAD);
|
||
|
|
else if ( (stream->_flag & _IOREAD) && (stream->_flag & _IOMYBUF) &&
|
||
|
|
!(stream->_flag & _IOSETVBUF) )
|
||
|
|
stream->_bufsiz = _SMALL_BUFSIZ;
|
||
|
|
|
||
|
|
/* Seek to the desired locale and return. */
|
||
|
|
|
||
|
|
return(_lseeki64(_fileno(stream), offset, whence) == -1i64 ? -1 : 0);
|
||
|
|
}
|