X-Git-Url: http://nsz.repo.hu/git/?p=musl;a=blobdiff_plain;f=src%2Fstdio%2F__lockfile.c;h=9d967d6eb8860c0522b9fcd8505d6e52fad19b6b;hp=6ebf6202bf189284b8d9a02d153259842a29a0cc;hb=41d7c77d6a2e74294807d35062e4cd1d48ab72d3;hpb=dba68bf98fc708cea4c478278c889fc7ad802b00

diff --git a/src/stdio/__lockfile.c b/src/stdio/__lockfile.c
index 6ebf6202..9d967d6e 100644
--- a/src/stdio/__lockfile.c
+++ b/src/stdio/__lockfile.c
@@ -8,11 +8,21 @@ int __lockfile(FILE *f)
 		return 0;
 	while ((owner = a_cas(&f->lock, 0, tid)))
 		__wait(&f->lock, &f->waiters, owner, 1);
-	return f->lockcount = 1;
+	return 1;
 }
 
 void __unlockfile(FILE *f)
 {
 	a_store(&f->lock, 0);
+
+	/* The following read is technically invalid under situations
+	 * of self-synchronized destruction. Another thread may have
+	 * called fclose as soon as the above store has completed.
+	 * Nonetheless, since FILE objects always live in memory
+	 * obtained by malloc from the heap, it's safe to assume
+	 * the dereferences below will not fault. In the worst case,
+	 * a spurious syscall will be made. If the implementation of
+	 * malloc changes, this assumption needs revisiting. */
+
 	if (f->waiters) __wake(&f->lock, 1, 1);
 }