1 files changed, 116 insertions, 0 deletions
diff --git a/main/sem.c b/main/sem.c
new file mode 100644
index 000000000..e67d9c72e
--- /dev/null
+++ b/main/sem.c
@@ -0,0 +1,116 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2013, Digium, Inc.
+ *
+ * David M. Lee, II <dlee@digium.com>
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+/*! \file
+ *
+ * \brief Asterisk semaphore support.
+ */
+
+#include "asterisk.h"
+
+ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
+
+#include "asterisk/sem.h"
+#include "asterisk/utils.h"
+
+#ifndef HAS_WORKING_SEMAPHORE
+
+/* DIY semaphores! */
+
+int ast_sem_init(struct ast_sem *sem, int pshared, unsigned int value)
+{
+	if (pshared) {
+		/* Don't need it... yet */
+		errno = ENOSYS;
+		return -1;
+	}
+
+	/* Since value is unsigned, this will also catch attempts to init with
+	 * a negative value */
+	if (value > AST_SEM_VALUE_MAX) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	sem->count = value;
+	sem->waiters = 0;
+	ast_mutex_init(&sem->mutex);
+	ast_cond_init(&sem->cond, NULL);
+	return 0;
+}
+
+int ast_sem_destroy(struct ast_sem *sem)
+{
+	ast_mutex_destroy(&sem->mutex);
+	ast_cond_destroy(&sem->cond);
+	return 0;
+}
+
+int ast_sem_post(struct ast_sem *sem)
+{
+	SCOPED_MUTEX(lock, &sem->mutex);
+
+	ast_assert(sem->count >= 0);
+
+	if (sem->count == AST_SEM_VALUE_MAX) {
+		errno = EOVERFLOW;
+		return -1;
+	}
+
+	/* Give it up! */
+	++sem->count;
+
+	/* Release a waiter, if needed */
+	if (sem->waiters) {
+		ast_cond_signal(&sem->cond);
+	}
+
+	return 0;
+}
+
+int ast_sem_wait(struct ast_sem *sem)
+{
+	SCOPED_MUTEX(lock, &sem->mutex);
+
+	ast_assert(sem->count >= 0);
+
+	/* Wait for a non-zero count */
+	++sem->waiters;
+	while (sem->count == 0) {
+		ast_cond_wait(&sem->cond, &sem->mutex);
+	}
+	--sem->waiters;
+
+	/* Take it! */
+	--sem->count;
+
+	return 0;
+}
+
+int ast_sem_getvalue(struct ast_sem *sem, int *sval)
+{
+	SCOPED_MUTEX(lock, &sem->mutex);
+
+	ast_assert(sem->count >= 0);
+
+	*sval = sem->count;
+
+	return 0;
+}
+
+#endif