mirror of
https://github.com/cc65/cc65.git
synced 2024-11-06 15:06:07 +00:00
61 lines
1.4 KiB
C
61 lines
1.4 KiB
C
/*
|
|
* fseek.c
|
|
*
|
|
* Christian Groessler, 2000-08-07
|
|
* Ullrich von Bassewitz, 2004-05-12
|
|
*/
|
|
|
|
|
|
|
|
#include <stdio.h>
|
|
#include <errno.h>
|
|
#include <unistd.h>
|
|
#include "_file.h"
|
|
|
|
|
|
|
|
/*****************************************************************************/
|
|
/* Code */
|
|
/*****************************************************************************/
|
|
|
|
|
|
|
|
int __fastcall__ fseek (register FILE* f, long offset, int whence)
|
|
{
|
|
long res;
|
|
|
|
/* Is the file open? */
|
|
if ((f->f_flags & _FOPEN) == 0) {
|
|
_errno = EINVAL; /* File not open */
|
|
return -1;
|
|
}
|
|
|
|
/* If we have a pushed back character, and whence is relative to the
|
|
* current position, correct the offset.
|
|
*/
|
|
if ((f->f_flags & _FPUSHBACK) && whence == SEEK_CUR) {
|
|
--offset;
|
|
}
|
|
|
|
/* Do the seek */
|
|
res = lseek(f->f_fd, offset, whence);
|
|
|
|
/* If we had an error, set the error indicator on the stream, and
|
|
* return -1. We will check for < 0 here, because that saves some code,
|
|
* and we don't have files with 2 gigabytes in size anyway:-)
|
|
*/
|
|
if (res < 0) {
|
|
f->f_flags |= _FERROR;
|
|
return -1;
|
|
}
|
|
|
|
/* The seek was successful. Discard any effects of the ungetc function,
|
|
* and clear the end-of-file indicator.
|
|
*/
|
|
f->f_flags &= ~(_FEOF | _FPUSHBACK);
|
|
|
|
/* Done */
|
|
return 0;
|
|
}
|
|
|