Add sem_*() functions. Named semaphores and process-shared semaphores

are not supported by this implementation, and the error return values
from sem_init(), sem_open(), sem_close(), and sem_unlink() reflect this.

Approved by:	jkh

3 files changed, 237 insertions, 0 deletions

diff --git a/lib/libc_r/uthread/Makefile.inc b/lib/libc_r/uthread/Makefile.inc
index f46f007a11cb..2a13365dfd3e 100644
--- a/lib/libc_r/uthread/Makefile.inc
+++ b/lib/libc_r/uthread/Makefile.inc
@@ -88,6 +88,7 @@ SRCS+= \
 	uthread_rwlockattr.c \
 	uthread_select.c \
 	uthread_self.c \
+	uthread_sem.c \
 	uthread_sendmsg.c \
 	uthread_sendto.c \
 	uthread_seterrno.c \
diff --git a/lib/libc_r/uthread/pthread_private.h b/lib/libc_r/uthread/pthread_private.h
index 560ea44d6145..00ca3b091ec1 100644
--- a/lib/libc_r/uthread/pthread_private.h
+++ b/lib/libc_r/uthread/pthread_private.h
@@ -309,6 +309,18 @@ struct pthread_cond_attr {
 	0, _SPINLOCK_INITIALIZER }
 
 /*
+ * Semaphore definitions.
+ */
+struct sem {
+#define	SEM_MAGIC	((u_int32_t) 0x09fa4012)
+	u_int32_t	magic;
+	pthread_mutex_t	lock;
+	pthread_cond_t	gtzero;
+	u_int32_t	count;
+	u_int32_t	nwaiters;
+};
+
+/*
  * Cleanup definitions.
  */
 struct pthread_cleanup {
diff --git a/lib/libc_r/uthread/uthread_sem.c b/lib/libc_r/uthread/uthread_sem.c
new file mode 100644
index 000000000000..8adb0d46d562
--- /dev/null
+++ b/lib/libc_r/uthread/uthread_sem.c
@@ -0,0 +1,224 @@
+/*
+ * Copyright (C) 2000 Jason Evans <jasone@canonware.com>.
+ * 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(s), this list of conditions and the following disclaimer as
+ *    the first lines of this file unmodified other than the possible
+ *    addition of one or more copyright notices.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice(s), 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 HOLDER(S) ``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(S) 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.
+ *
+ * $FreeBSD$
+ */
+
+#include <errno.h>
+#ifdef _THREAD_SAFE
+#include <semaphore.h>
+#include <pthread.h>
+#include "pthread_private.h"
+
+#define _SEM_CHECK_VALIDITY(sem)		\
+	if ((*(sem))->magic != SEM_MAGIC) {	\
+		retval = EINVAL;		\
+		goto RETURN;			\
+	}
+
+int
+sem_init(sem_t *sem, int pshared, unsigned int value)
+{
+	int	retval;
+
+	/*
+	 * Range check the arguments.
+	 */
+	if (pshared != 0) {
+		/*
+		 * The user wants a semaphore that can be shared among
+		 * processes, which this implementation can't do.  Sounds like a
+		 * permissions problem to me (yeah right).
+		 */
+		retval = EPERM;
+		goto RETURN;
+	}
+
+	if (value > SEM_VALUE_MAX) {
+		retval = EINVAL;
+		goto RETURN;
+	}
+
+	*sem = (sem_t)malloc(sizeof(struct sem));
+	if (*sem == NULL) {
+		retval = ENOSPC;
+		goto RETURN;
+	}
+
+	/*
+	 * Initialize the semaphore.
+	 */
+	retval = pthread_mutex_init(&(*sem)->lock, NULL);
+	if (retval != 0) {
+		free(*sem);
+		goto RETURN;
+	}
+
+	retval = pthread_cond_init(&(*sem)->gtzero, NULL);
+	if (retval != 0) {
+		pthread_mutex_destroy(&(*sem)->lock);
+		free(*sem);
+		goto RETURN;
+	}
+	
+	(*sem)->count = (u_int32_t)value;
+	(*sem)->nwaiters = 0;
+	(*sem)->magic = SEM_MAGIC;
+
+  RETURN:
+	return retval;
+}
+
+int
+sem_destroy(sem_t *sem)
+{
+	int	retval;
+	
+	_SEM_CHECK_VALIDITY(sem);
+
+	/* Make sure there are no waiters. */
+	pthread_mutex_lock(&(*sem)->lock);
+	if ((*sem)->nwaiters > 0) {
+		pthread_mutex_unlock(&(*sem)->lock);
+		retval = EBUSY;
+		goto RETURN;
+	}
+	pthread_mutex_unlock(&(*sem)->lock);
+	
+	pthread_mutex_destroy(&(*sem)->lock);
+	pthread_cond_destroy(&(*sem)->gtzero);
+	(*sem)->magic = 0;
+
+	free(*sem);
+
+	retval = 0;
+  RETURN:
+	return retval;
+}
+
+sem_t *
+sem_open(const char * name, int oflag, ...)
+{
+	errno = ENOSYS;
+	return SEM_FAILED;
+}
+
+int
+sem_close(sem_t *sem)
+{
+	errno = ENOSYS;
+	return -1;
+}
+
+int
+sem_unlink(const char *name)
+{
+	errno = ENOSYS;
+	return -1;
+}
+
+int
+sem_wait(sem_t *sem)
+{
+	int	retval;
+	
+	_SEM_CHECK_VALIDITY(sem);
+
+	pthread_mutex_lock(&(*sem)->lock);
+
+	while ((*sem)->count == 0) {
+		(*sem)->nwaiters++;
+		pthread_cond_wait(&(*sem)->gtzero, &(*sem)->lock);
+		(*sem)->nwaiters--;
+	}
+	(*sem)->count--;
+
+	pthread_mutex_unlock(&(*sem)->lock);
+
+	retval = 0;
+  RETURN:
+	return retval;
+}
+
+int
+sem_trywait(sem_t *sem)
+{
+	int	retval;
+
+	_SEM_CHECK_VALIDITY(sem);
+
+	pthread_mutex_lock(&(*sem)->lock);
+
+	if ((*sem)->count > 0) {
+		(*sem)->count--;
+		retval = 0;
+	} else
+		retval = EAGAIN;
+
+	pthread_mutex_unlock(&(*sem)->lock);
+
+  RETURN:
+	return retval;
+}
+
+int
+sem_post(sem_t *sem)
+{
+	int	retval;
+
+	_SEM_CHECK_VALIDITY(sem);
+
+	pthread_mutex_lock(&(*sem)->lock);
+
+	(*sem)->count++;
+	if ((*sem)->nwaiters > 0)
+		pthread_cond_signal(&(*sem)->gtzero);
+
+	pthread_mutex_unlock(&(*sem)->lock);
+
+	retval = 0;
+  RETURN:
+	return retval;
+}
+
+int
+sem_getvalue(sem_t *sem, int *sval)
+{
+	int	retval;
+
+	_SEM_CHECK_VALIDITY(sem);
+
+	pthread_mutex_lock(&(*sem)->lock);
+	*sval = (int)(*sem)->count;
+	pthread_mutex_unlock(&(*sem)->lock);
+
+	retval = 0;
+  RETURN:
+	return retval;
+}
+#endif