Add unnamed semaphore implementation for Mac OS X

In the past we relied on libosxfuse including a working unnamed semaphore
implmentation for Mac OS X. This will not be the case in future releases of
OSXFUSE, therefore we need to add our own implementation.

2 files changed, 297 insertions, 0 deletions

diff --git a/compat/darwin_compat.c b/compat/darwin_compat.c
new file mode 100644
index 0000000..3883ec6
--- /dev/null
+++ b/compat/darwin_compat.c
@@ -0,0 +1,246 @@
+/*
+ * Copyright (c) 2006-2008 Amit Singh/Google Inc.
+ * Copyright (c) 2012 Anatol Pomozov
+ * Copyright (c) 2011-2012 Benjamin Fleischer
+ */
+
+#include "darwin_compat.h"
+
+#include <assert.h>
+#include <errno.h>
+#include <sys/types.h>
+
+/*
+ * Semaphore implementation based on:
+ *
+ * Copyright (C) 2000,02 Free Software Foundation, Inc.
+ * This file is part of the GNU C Library.
+ * Written by Ga<EB>l Le Mignot <address@hidden>
+ *
+ * The GNU C Library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * The GNU C Library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with the GNU C Library; see the file COPYING.LIB.  If not,
+ * write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+/* Semaphores */
+
+#define __SEM_ID_NONE  ((int)0x0)
+#define __SEM_ID_LOCAL ((int)0xcafef00d)
+
+/* http://www.opengroup.org/onlinepubs/007908799/xsh/sem_init.html */
+int
+darwin_sem_init(darwin_sem_t *sem, int pshared, unsigned int value)
+{
+    if (pshared) {
+        errno = ENOSYS;
+        return -1;
+    }
+
+    sem->id = __SEM_ID_NONE;
+
+    if (pthread_cond_init(&sem->__data.local.count_cond, NULL)) {
+        goto cond_init_fail;
+    }
+
+    if (pthread_mutex_init(&sem->__data.local.count_lock, NULL)) {
+        goto mutex_init_fail;
+    }
+
+    sem->__data.local.count = value;
+    sem->id = __SEM_ID_LOCAL;
+
+    return 0;
+
+mutex_init_fail:
+
+    pthread_cond_destroy(&sem->__data.local.count_cond);
+
+cond_init_fail:
+
+    return -1;
+}
+
+/* http://www.opengroup.org/onlinepubs/007908799/xsh/sem_destroy.html */
+int
+darwin_sem_destroy(darwin_sem_t *sem)
+{
+    int res = 0;
+
+    pthread_mutex_lock(&sem->__data.local.count_lock);
+
+    sem->id = __SEM_ID_NONE;
+    pthread_cond_broadcast(&sem->__data.local.count_cond);
+
+    if (pthread_cond_destroy(&sem->__data.local.count_cond)) {
+        res = -1;
+    }
+
+    pthread_mutex_unlock(&sem->__data.local.count_lock);
+
+    if (pthread_mutex_destroy(&sem->__data.local.count_lock)) {
+        res = -1;
+    }
+
+    return res;
+}
+
+int
+darwin_sem_getvalue(darwin_sem_t *sem, unsigned int *sval)
+{
+    int res = 0;
+
+    pthread_mutex_lock(&sem->__data.local.count_lock);
+
+    if (sem->id != __SEM_ID_LOCAL) {
+        res = -1;
+        errno = EINVAL;
+    } else {
+        *sval = sem->__data.local.count;
+    }
+
+    pthread_mutex_unlock(&sem->__data.local.count_lock);
+
+    return res;
+}
+
+/* http://www.opengroup.org/onlinepubs/007908799/xsh/sem_post.html */
+int
+darwin_sem_post(darwin_sem_t *sem)
+{
+    int res = 0;
+
+    pthread_mutex_lock(&sem->__data.local.count_lock);
+
+    if (sem->id != __SEM_ID_LOCAL) {
+        res = -1;
+        errno = EINVAL;
+    } else if (sem->__data.local.count < DARWIN_SEM_VALUE_MAX) {
+        sem->__data.local.count++;
+        if (sem->__data.local.count == 1) {
+            pthread_cond_signal(&sem->__data.local.count_cond);
+        }
+    } else {
+        errno = ERANGE;
+        res = -1;
+    }
+
+    pthread_mutex_unlock(&sem->__data.local.count_lock);
+
+    return res;
+}
+
+/* http://www.opengroup.org/onlinepubs/009695399/functions/sem_timedwait.html */
+int
+darwin_sem_timedwait(darwin_sem_t *sem, const struct timespec *abs_timeout)
+{
+    int res = 0;
+
+    if (abs_timeout &&
+        (abs_timeout->tv_nsec < 0 || abs_timeout->tv_nsec >= 1000000000)) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    pthread_cleanup_push((void(*)(void*))&pthread_mutex_unlock,
+                 &sem->__data.local.count_lock);
+
+    pthread_mutex_lock(&sem->__data.local.count_lock);
+
+    if (sem->id != __SEM_ID_LOCAL) {
+        errno = EINVAL;
+        res = -1;
+    } else {
+        if (!sem->__data.local.count) {
+            res = pthread_cond_timedwait(&sem->__data.local.count_cond,
+                             &sem->__data.local.count_lock,
+                             abs_timeout);
+        }
+        if (res) {
+            assert(res == ETIMEDOUT);
+            res = -1;
+            errno = ETIMEDOUT;
+        } else if (sem->id != __SEM_ID_LOCAL) {
+            res = -1;
+            errno = EINVAL;
+        } else {
+            sem->__data.local.count--;
+        }
+    }
+
+    pthread_cleanup_pop(1);
+
+    return res;
+}
+
+/* http://www.opengroup.org/onlinepubs/007908799/xsh/sem_trywait.html */
+int
+darwin_sem_trywait(darwin_sem_t *sem)
+{
+    int res = 0;
+
+    pthread_mutex_lock(&sem->__data.local.count_lock);
+
+    if (sem->id != __SEM_ID_LOCAL) {
+        res = -1;
+        errno = EINVAL;
+    } else if (sem->__data.local.count) {
+        sem->__data.local.count--;
+    } else {
+        res = -1;
+        errno = EAGAIN;
+    }
+
+    pthread_mutex_unlock (&sem->__data.local.count_lock);
+
+    return res;
+}
+
+/* http://www.opengroup.org/onlinepubs/007908799/xsh/sem_wait.html */
+int
+darwin_sem_wait(darwin_sem_t *sem)
+{
+    int res = 0;
+
+    pthread_cleanup_push((void(*)(void*))&pthread_mutex_unlock,
+                 &sem->__data.local.count_lock);
+
+    pthread_mutex_lock(&sem->__data.local.count_lock);
+
+    if (sem->id != __SEM_ID_LOCAL) {
+        errno = EINVAL;
+        res = -1;
+    } else {
+        if (!sem->__data.local.count) {
+            pthread_cond_wait(&sem->__data.local.count_cond,
+                      &sem->__data.local.count_lock);
+            if (!sem->__data.local.count) {
+                /* spurious wakeup, assume it is an interruption */
+                res = -1;
+                errno = EINTR;
+                goto out;
+            }
+        }
+        if (sem->id != __SEM_ID_LOCAL) {
+            res = -1;
+            errno = EINVAL;
+        } else {
+            sem->__data.local.count--;
+        }
+    }
+
+out:
+    pthread_cleanup_pop(1);
+
+    return res;
+}
diff --git a/compat/darwin_compat.h b/compat/darwin_compat.h
new file mode 100644
index 0000000..1cdbcce
--- /dev/null
+++ b/compat/darwin_compat.h
@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2006-2008 Amit Singh/Google Inc.
+ * Copyright (c) 2011-2012 Benjamin Fleischer
+ */
+
+#ifndef _DARWIN_COMPAT_
+#define _DARWIN_COMPAT_
+
+#include <pthread.h>
+
+/* Semaphores */
+
+struct __local_sem_t
+{
+    unsigned int    count;
+    pthread_mutex_t count_lock;
+    pthread_cond_t  count_cond;
+};
+
+typedef struct fuse_sem {
+    int id;
+    union {
+        struct __local_sem_t local;
+    } __data;
+} darwin_sem_t;
+
+#define DARWIN_SEM_VALUE_MAX ((int32_t)32767)
+
+int darwin_sem_init(darwin_sem_t *sem, int pshared, unsigned int value);
+int darwin_sem_destroy(darwin_sem_t *sem);
+int darwin_sem_getvalue(darwin_sem_t *sem, unsigned int *value);
+int darwin_sem_post(darwin_sem_t *sem);
+int darwin_sem_timedwait(darwin_sem_t *sem, const struct timespec *abs_timeout);
+int darwin_sem_trywait(darwin_sem_t *sem);
+int darwin_sem_wait(darwin_sem_t *sem);
+
+/* Caller must not include <semaphore.h> */
+
+typedef darwin_sem_t sem_t;
+
+#define sem_init(s, p, v)   darwin_sem_init(s, p, v)
+#define sem_destroy(s)      darwin_sem_destroy(s)
+#define sem_getvalue(s, v)  darwin_sem_getvalue(s, v)
+#define sem_post(s)         darwin_sem_post(s)
+#define sem_timedwait(s, t) darwin_sem_timedwait(s, t)
+#define sem_trywait(s)      darwin_sem_trywait(s)
+#define sem_wait(s)         darwin_sem_wait(s)
+
+#define SEM_VALUE_MAX       DARWIN_SEM_VALUE_MAX
+
+#endif /* _DARWIN_COMPAT_ */