minimal plan9port to cross-build Jehanne

lib/lib9/lock.c

@@ -0,0 +1,55 @@
+#include <u.h>
+#include <unistd.h>
+#include <sys/time.h>
+#include <sched.h>
+#include <errno.h>
+#include <libc.h>
+
+static pthread_mutex_t initmutex = PTHREAD_MUTEX_INITIALIZER;
+
+static void
+lockinit(Lock *lk)
+{
+	pthread_mutexattr_t attr;
+
+	pthread_mutex_lock(&initmutex);
+	if(lk->init == 0){
+		pthread_mutexattr_init(&attr);
+		pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_NORMAL);
+		pthread_mutex_init(&lk->mutex, &attr);
+		pthread_mutexattr_destroy(&attr);
+		lk->init = 1;
+	}
+	pthread_mutex_unlock(&initmutex);
+}
+
+void
+lock(Lock *lk)
+{
+	if(!lk->init)
+		lockinit(lk);
+	if(pthread_mutex_lock(&lk->mutex) != 0)
+		abort();
+}
+
+int
+canlock(Lock *lk)
+{
+	int r;
+
+	if(!lk->init)
+		lockinit(lk);
+	r = pthread_mutex_trylock(&lk->mutex);
+	if(r == 0)
+		return 1;
+	if(r == EBUSY)
+		return 0;
+	abort();
+}
+
+void
+unlock(Lock *lk)
+{
+	if(pthread_mutex_unlock(&lk->mutex) != 0)
+		abort();
+}