| 1 | #include "stdio_impl.h" |
| 2 | #include <errno.h> |
| 3 | |
| 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 | |
| 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 | |
| 43 | int fseek(FILE *f, long off, int whence) |
| 44 | { |
| 45 | return __fseeko(f, off, whence); |
| 46 | } |
| 47 | |
| 48 | weak_alias(__fseeko, fseeko); |
| 49 | |
| 50 | weak_alias(fseeko, fseeko64); |