1#include "stdio_impl.h" 2#include "pthread_impl.h" 3 4int __lockfile(FILE *f) 5{ 6 int owner = f->lock, tid = __pthread_self()->tid; 7 if ((owner & ~MAYBE_WAITERS) == tid) 8 return 0; 9 owner = a_cas(&f->lock, 0, tid); 10 if (!owner) return 1; 11 while ((owner = a_cas(&f->lock, 0, tid|MAYBE_WAITERS))) { 12 if ((owner & MAYBE_WAITERS) || 13 a_cas(&f->lock, owner, owner|MAYBE_WAITERS)==owner) 14 __futexwait(&f->lock, owner|MAYBE_WAITERS, 1); 15 } 16 return 1; 17} 18 19void __unlockfile(FILE *f) 20{ 21 if (a_swap(&f->lock, 0) & MAYBE_WAITERS) 22 __wake(&f->lock, 1, 1); 23} 24