src/stdio/__lockfile.c

570af302Sopenharmony_ci#include "stdio_impl.h"
570af302Sopenharmony_ci#include "pthread_impl.h"
570af302Sopenharmony_ci
570af302Sopenharmony_ciint __lockfile(FILE *f)
570af302Sopenharmony_ci{
570af302Sopenharmony_ci	int owner = f->lock, tid = __pthread_self()->tid;
570af302Sopenharmony_ci	if ((owner & ~MAYBE_WAITERS) == tid)
570af302Sopenharmony_ci		return 0;
570af302Sopenharmony_ci	owner = a_cas(&f->lock, 0, tid);
570af302Sopenharmony_ci	if (!owner) return 1;
570af302Sopenharmony_ci	while ((owner = a_cas(&f->lock, 0, tid|MAYBE_WAITERS))) {
570af302Sopenharmony_ci		if ((owner & MAYBE_WAITERS) ||
570af302Sopenharmony_ci		    a_cas(&f->lock, owner, owner|MAYBE_WAITERS)==owner)
570af302Sopenharmony_ci			__futexwait(&f->lock, owner|MAYBE_WAITERS, 1);
570af302Sopenharmony_ci	}
570af302Sopenharmony_ci	return 1;
570af302Sopenharmony_ci}
570af302Sopenharmony_ci
570af302Sopenharmony_civoid __unlockfile(FILE *f)
570af302Sopenharmony_ci{
570af302Sopenharmony_ci	if (a_swap(&f->lock, 0) & MAYBE_WAITERS)
570af302Sopenharmony_ci		__wake(&f->lock, 1, 1);
570af302Sopenharmony_ci}