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1 #include "stdio_impl.h" | 1 #include "stdio_impl.h" |
2 #include "pthread_impl.h" | 2 #include "pthread_impl.h" |
3 | 3 |
4 int __lockfile(FILE *f) | 4 int __lockfile(FILE* f) { |
5 { | 5 int owner, tid = __pthread_self()->tid; |
6 » int owner, tid = __pthread_self()->tid; | 6 if (f->lock == tid) |
7 » if (f->lock == tid) | 7 return 0; |
8 » » return 0; | 8 while ((owner = a_cas(&f->lock, 0, tid))) |
9 » while ((owner = a_cas(&f->lock, 0, tid))) | 9 __wait(&f->lock, &f->waiters, owner, 1); |
10 » » __wait(&f->lock, &f->waiters, owner, 1); | 10 return 1; |
11 » return 1; | |
12 } | 11 } |
13 | 12 |
14 void __unlockfile(FILE *f) | 13 void __unlockfile(FILE* f) { |
15 { | 14 a_store(&f->lock, 0); |
16 » a_store(&f->lock, 0); | |
17 | 15 |
18 » /* The following read is technically invalid under situations | 16 /* The following read is technically invalid under situations |
19 » * of self-synchronized destruction. Another thread may have | 17 * of self-synchronized destruction. Another thread may have |
20 » * called fclose as soon as the above store has completed. | 18 * called fclose as soon as the above store has completed. |
21 » * Nonetheless, since FILE objects always live in memory | 19 * Nonetheless, since FILE objects always live in memory |
22 » * obtained by malloc from the heap, it's safe to assume | 20 * obtained by malloc from the heap, it's safe to assume |
23 » * the dereferences below will not fault. In the worst case, | 21 * the dereferences below will not fault. In the worst case, |
24 » * a spurious syscall will be made. If the implementation of | 22 * a spurious syscall will be made. If the implementation of |
25 » * malloc changes, this assumption needs revisiting. */ | 23 * malloc changes, this assumption needs revisiting. */ |
26 | 24 |
27 » if (f->waiters) __wake(&f->lock, 1, 1); | 25 if (f->waiters) |
| 26 __wake(&f->lock, 1, 1); |
28 } | 27 } |
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