--- /dev/null
+/*-
+ * Copyright (c) 1997,98 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by J.T. Conklin.
+ *
+ * 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.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the NetBSD
+ * Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ * contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
+ *
+ * $FreeBSD: src/lib/libc/include/reentrant.h,v 1.3 2004/02/25 21:03:45 green Exp $
+ */
+
+/*
+ * Requirements:
+ *
+ * 1. The thread safe mechanism should be lightweight so the library can
+ * be used by non-threaded applications without unreasonable overhead.
+ *
+ * 2. There should be no dependency on a thread engine for non-threaded
+ * applications.
+ *
+ * 3. There should be no dependency on any particular thread engine.
+ *
+ * 4. The library should be able to be compiled without support for thread
+ * safety.
+ *
+ *
+ * Rationale:
+ *
+ * One approach for thread safety is to provide discrete versions of the
+ * library: one thread safe, the other not. The disadvantage of this is
+ * that libc is rather large, and two copies of a library which are 99%+
+ * identical is not an efficent use of resources.
+ *
+ * Another approach is to provide a single thread safe library. However,
+ * it should not add significant run time or code size overhead to non-
+ * threaded applications.
+ *
+ * Since the NetBSD C library is used in other projects, it should be
+ * easy to replace the mutual exclusion primitives with ones provided by
+ * another system. Similarly, it should also be easy to remove all
+ * support for thread safety completely if the target environment does
+ * not support threads.
+ *
+ *
+ * Implementation Details:
+ *
+ * The mutex primitives used by the library (mutex_t, mutex_lock, etc.)
+ * are macros which expand to the cooresponding primitives provided by
+ * the thread engine or to nothing. The latter is used so that code is
+ * not unreasonably cluttered with #ifdefs when all thread safe support
+ * is removed.
+ *
+ * The mutex macros can be directly mapped to the mutex primitives from
+ * pthreads, however it should be reasonably easy to wrap another mutex
+ * implementation so it presents a similar interface.
+ *
+ * Stub implementations of the mutex functions are provided with *weak*
+ * linkage. These functions simply return success. When linked with a
+ * thread library (i.e. -lpthread), the functions will override the
+ * stubs.
+ */
+
+#include <pthread.h>
+#include "libc_private.h"
+
+#define mutex_t pthread_mutex_t
+#define cond_t pthread_cond_t
+#define rwlock_t pthread_rwlock_t
+#define once_t pthread_once_t
+
+#define thread_key_t pthread_key_t
+#define MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER
+#define RWLOCK_INITIALIZER PTHREAD_RWLOCK_INITIALIZER
+#define ONCE_INITIALIZER PTHREAD_ONCE_INIT
+
+#define mutex_init(m, a) _pthread_mutex_init(m, a)
+#define mutex_lock(m) if (__isthreaded) \
+ _pthread_mutex_lock(m)
+#define mutex_unlock(m) if (__isthreaded) \
+ _pthread_mutex_unlock(m)
+#define mutex_trylock(m) (__isthreaded ? 0 : _pthread_mutex_trylock(m))
+
+#define cond_init(c, a, p) _pthread_cond_init(c, a)
+#define cond_signal(m) if (__isthreaded) \
+ _pthread_cond_signal(m)
+#define cond_broadcast(m) if (__isthreaded) \
+ _pthread_cond_broadcast(m)
+#define cond_wait(c, m) if (__isthreaded) \
+ _pthread_cond_wait(c, m)
+
+#define rwlock_init(l, a) _pthread_rwlock_init(l, a)
+#define rwlock_rdlock(l) if (__isthreaded) \
+ _pthread_rwlock_rdlock(l)
+#define rwlock_wrlock(l) if (__isthreaded) \
+ _pthread_rwlock_wrlock(l)
+#define rwlock_unlock(l) if (__isthreaded) \
+ _pthread_rwlock_unlock(l)
+
+#define thr_keycreate(k, d) _pthread_key_create(k, d)
+#define thr_setspecific(k, p) _pthread_setspecific(k, p)
+#define thr_getspecific(k) _pthread_getspecific(k)
+#define thr_sigsetmask(f, n, o) _pthread_sigmask(f, n, o)
+
+#define thr_once(o, i) _pthread_once(o, i)
+#define thr_self() _pthread_self()
+#define thr_exit(x) _pthread_exit(x)
+#define thr_main() _pthread_main_np()
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