LibPthread: Implement semaphore functions

Userland/Libraries/LibPthread/semaphore.cpp

@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2021, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/Assertions.h>
+#include <errno.h>
+#include <semaphore.h>
+
+int sem_close(sem_t*)
+{
+    errno = ENOSYS;
+    return -1;
+}
+
+int sem_destroy(sem_t* sem)
+{
+    pthread_mutex_destroy(&sem->mtx);
+    pthread_cond_destroy(&sem->cv);
+    return 0;
+}
+
+int sem_getvalue(sem_t*, int*)
+{
+    VERIFY_NOT_REACHED();
+}
+
+int sem_init(sem_t* sem, int shared, unsigned int value)
+{
+    if (shared)
+        return ENOSYS;
+
+    if (pthread_mutex_init(&sem->mtx, nullptr) != 0)
+        return -1;
+
+    if (pthread_cond_init(&sem->cv, nullptr) != 0)
+        return -1;
+
+    sem->value = value;
+
+    return 0;
+}
+
+sem_t* sem_open(const char*, int, ...)
+{
+    errno = ENOSYS;
+    return nullptr;
+}
+
+int sem_post(sem_t* sem)
+{
+    sem->value++;
+
+    pthread_cond_signal(&sem->cv);
+
+    pthread_mutex_unlock(&sem->mtx);
+
+    return 0;
+}
+
+int sem_trywait(sem_t* sem)
+{
+    if (pthread_mutex_lock(&sem->mtx) != 0)
+        return -1;
+
+    if (sem->value == 0) {
+        pthread_mutex_unlock(&sem->mtx);
+        errno = EAGAIN;
+        return -1;
+    }
+
+    sem->value--;
+
+    return 0;
+}
+
+int sem_unlink(const char*)
+{
+    return ENOSYS;
+}
+
+int sem_wait(sem_t* sem)
+{
+    if (pthread_mutex_lock(&sem->mtx) != 0)
+        return -1;
+
+    while (sem->value == 0) {
+        if (pthread_cond_wait(&sem->cv, &sem->mtx) != 0) {
+            pthread_mutex_unlock(&sem->mtx);
+            return -1;
+        }
+    }
+
+    sem->value--;
+
+    return 0;
+}