24 lines
551 B
C
24 lines
551 B
C
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#include "stdio_impl.h"
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#include "pthread_impl.h"
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int __lockfile(FILE *f)
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{
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int owner = f->lock, tid = __pthread_self()->tid;
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if ((owner & ~MAYBE_WAITERS) == tid)
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return 0;
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owner = a_cas(&f->lock, 0, tid);
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if (!owner) return 1;
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while ((owner = a_cas(&f->lock, 0, tid|MAYBE_WAITERS))) {
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if ((owner & MAYBE_WAITERS) ||
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a_cas(&f->lock, owner, owner|MAYBE_WAITERS)==owner)
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__futexwait(&f->lock, owner|MAYBE_WAITERS, 1);
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}
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return 1;
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}
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void __unlockfile(FILE *f)
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{
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if (a_swap(&f->lock, 0) & MAYBE_WAITERS)
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__wake(&f->lock, 1, 1);
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}
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