2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 1997,98 The NetBSD Foundation, Inc.
7 * This code is derived from software contributed to The NetBSD Foundation
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
37 * 1. The thread safe mechanism should be lightweight so the library can
38 * be used by non-threaded applications without unreasonable overhead.
40 * 2. There should be no dependency on a thread engine for non-threaded
43 * 3. There should be no dependency on any particular thread engine.
45 * 4. The library should be able to be compiled without support for thread
51 * One approach for thread safety is to provide discrete versions of the
52 * library: one thread safe, the other not. The disadvantage of this is
53 * that libc is rather large, and two copies of a library which are 99%+
54 * identical is not an efficient use of resources.
56 * Another approach is to provide a single thread safe library. However,
57 * it should not add significant run time or code size overhead to non-
58 * threaded applications.
60 * Since the NetBSD C library is used in other projects, it should be
61 * easy to replace the mutual exclusion primitives with ones provided by
62 * another system. Similarly, it should also be easy to remove all
63 * support for thread safety completely if the target environment does
64 * not support threads.
67 * Implementation Details:
69 * The mutex primitives used by the library (mutex_t, mutex_lock, etc.)
70 * are macros which expand to the corresponding primitives provided by
71 * the thread engine or to nothing. The latter is used so that code is
72 * not unreasonably cluttered with #ifdefs when all thread safe support
75 * The mutex macros can be directly mapped to the mutex primitives from
76 * pthreads, however it should be reasonably easy to wrap another mutex
77 * implementation so it presents a similar interface.
79 * Stub implementations of the mutex functions are provided with *weak*
80 * linkage. These functions simply return success. When linked with a
81 * thread library (i.e. -lpthread), the functions will override the
86 #include <pthread_np.h>
87 #include "libc_private.h"
89 #define mutex_t pthread_mutex_t
90 #define cond_t pthread_cond_t
91 #define rwlock_t pthread_rwlock_t
92 #define once_t pthread_once_t
94 #define thread_key_t pthread_key_t
95 #define MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER
96 #define RWLOCK_INITIALIZER PTHREAD_RWLOCK_INITIALIZER
97 #define ONCE_INITIALIZER PTHREAD_ONCE_INIT
99 #define mutex_init(m, a) _pthread_mutex_init(m, a)
100 #define mutex_lock(m) if (__isthreaded) \
101 _pthread_mutex_lock(m)
102 #define mutex_unlock(m) if (__isthreaded) \
103 _pthread_mutex_unlock(m)
104 #define mutex_trylock(m) (__isthreaded ? 0 : _pthread_mutex_trylock(m))
106 #define cond_init(c, a, p) _pthread_cond_init(c, a)
107 #define cond_signal(m) if (__isthreaded) \
108 _pthread_cond_signal(m)
109 #define cond_broadcast(m) if (__isthreaded) \
110 _pthread_cond_broadcast(m)
111 #define cond_wait(c, m) if (__isthreaded) \
112 _pthread_cond_wait(c, m)
114 #define rwlock_init(l, a) _pthread_rwlock_init(l, a)
115 #define rwlock_rdlock(l) if (__isthreaded) \
116 _pthread_rwlock_rdlock(l)
117 #define rwlock_wrlock(l) if (__isthreaded) \
118 _pthread_rwlock_wrlock(l)
119 #define rwlock_unlock(l) if (__isthreaded) \
120 _pthread_rwlock_unlock(l)
122 #define thr_keycreate(k, d) _pthread_key_create(k, d)
123 #define thr_setspecific(k, p) _pthread_setspecific(k, p)
124 #define thr_getspecific(k) _pthread_getspecific(k)
125 #define thr_sigsetmask(f, n, o) _pthread_sigmask(f, n, o)
127 #define thr_once(o, i) _pthread_once(o, i)
128 #define thr_self() _pthread_self()
129 #define thr_exit(x) _pthread_exit(x)
130 #define thr_main() _pthread_main_np()