1 #include "stdio_impl.h"
2 #include <errno.h>
3
__fseeko_unlocked(FILE * f,off_t off,int whence)4 int __fseeko_unlocked(FILE *f, off_t off, int whence)
5 {
6 /* Fail immediately for invalid whence argument. */
7 if (whence != SEEK_CUR && whence != SEEK_SET && whence != SEEK_END) {
8 errno = EINVAL;
9 return -1;
10 }
11
12 /* Adjust relative offset for unread data in buffer, if any. */
13 if (whence == SEEK_CUR && f->rend) off -= f->rend - f->rpos;
14
15 /* Flush write buffer, and report error on failure. */
16 if (f->wpos != f->wbase) {
17 f->write(f, 0, 0);
18 if (!f->wpos) return -1;
19 }
20
21 /* Leave writing mode */
22 f->wpos = f->wbase = f->wend = 0;
23
24 /* Perform the underlying seek. */
25 if (f->seek(f, off, whence) < 0) return -1;
26
27 /* If seek succeeded, file is seekable and we discard read buffer. */
28 f->rpos = f->rend = 0;
29 f->flags &= ~F_EOF;
30
31 return 0;
32 }
33
__fseeko(FILE * f,off_t off,int whence)34 int __fseeko(FILE *f, off_t off, int whence)
35 {
36 int result;
37 FLOCK(f);
38 result = __fseeko_unlocked(f, off, whence);
39 FUNLOCK(f);
40 return result;
41 }
42
fseek(FILE * f,long off,int whence)43 int fseek(FILE *f, long off, int whence)
44 {
45 return __fseeko(f, off, whence);
46 }
47
48 weak_alias(__fseeko, fseeko);
49