implement flockfile api, rework stdio locking

1 files changed, 19 insertions, 0 deletions

diff --git a/src/stdio/__lockfile.c b/src/stdio/__lockfile.c
new file mode 100644
index 00000000..82f50b42
--- /dev/null
+++ b/src/stdio/__lockfile.c
@@ -0,0 +1,19 @@
+#include "stdio_impl.h"
+#include "pthread_impl.h"
+
+void __lockfile(FILE *f)
+{
+	int spins;
+	if (f->owner < 0) return;
+	if (f->owner && f->owner == __pthread_self()->tid) {
+		while (f->lockcount == INT_MAX);
+		f->lockcount++;
+		return;
+	}
+	spins = 100000;
+	while (a_swap(&f->lock, 1))
+		if (spins) spins--, a_spin();
+		else syscall0(__NR_sched_yield);
+	f->owner = __pthread_self()->tid;
+	f->lockcount = 1;
+}