1 /*- 2 * Copyright (c) 1997,98 The NetBSD Foundation, Inc. 3 * All rights reserved. 4 * 5 * This code is derived from software contributed to The NetBSD Foundation 6 * by J.T. Conklin. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the NetBSD 19 * Foundation, Inc. and its contributors. 20 * 4. Neither the name of The NetBSD Foundation nor the names of its 21 * contributors may be used to endorse or promote products derived 22 * from this software without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 25 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 26 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 27 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 28 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 29 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 30 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 31 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 32 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 33 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 34 * POSSIBILITY OF SUCH DAMAGE. 35 * 36 * $FreeBSD: src/lib/libc/include/reentrant.h,v 1.3 2004/02/25 21:03:45 green Exp $ 37 * $DragonFly$ 38 */ 39 40 /* 41 * Requirements: 42 * 43 * 1. The thread safe mechanism should be lightweight so the library can 44 * be used by non-threaded applications without unreasonable overhead. 45 * 46 * 2. There should be no dependency on a thread engine for non-threaded 47 * applications. 48 * 49 * 3. There should be no dependency on any particular thread engine. 50 * 51 * 4. The library should be able to be compiled without support for thread 52 * safety. 53 * 54 * 55 * Rationale: 56 * 57 * One approach for thread safety is to provide discrete versions of the 58 * library: one thread safe, the other not. The disadvantage of this is 59 * that libc is rather large, and two copies of a library which are 99%+ 60 * identical is not an efficent use of resources. 61 * 62 * Another approach is to provide a single thread safe library. However, 63 * it should not add significant run time or code size overhead to non- 64 * threaded applications. 65 * 66 * Since the NetBSD C library is used in other projects, it should be 67 * easy to replace the mutual exclusion primitives with ones provided by 68 * another system. Similarly, it should also be easy to remove all 69 * support for thread safety completely if the target environment does 70 * not support threads. 71 * 72 * 73 * Implementation Details: 74 * 75 * The mutex primitives used by the library (mutex_t, mutex_lock, etc.) 76 * are macros which expand to the cooresponding primitives provided by 77 * the thread engine or to nothing. The latter is used so that code is 78 * not unreasonably cluttered with #ifdefs when all thread safe support 79 * is removed. 80 * 81 * The mutex macros can be directly mapped to the mutex primitives from 82 * pthreads, however it should be reasonably easy to wrap another mutex 83 * implementation so it presents a similar interface. 84 * 85 * Stub implementations of the mutex functions are provided with *weak* 86 * linkage. These functions simply return success. When linked with a 87 * thread library (i.e. -lpthread), the functions will override the 88 * stubs. 89 */ 90 91 #include <pthread.h> 92 #include <pthread_np.h> 93 #include "libc_private.h" 94 95 #define mutex_t pthread_mutex_t 96 #define cond_t pthread_cond_t 97 #define rwlock_t pthread_rwlock_t 98 #define once_t pthread_once_t 99 100 #define thread_key_t pthread_key_t 101 #define MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER 102 #define RWLOCK_INITIALIZER PTHREAD_RWLOCK_INITIALIZER 103 #define ONCE_INITIALIZER PTHREAD_ONCE_INIT 104 105 #define mutex_init(m, a) _pthread_mutex_init(m, a) 106 #define mutex_lock(m) if (__isthreaded) \ 107 _pthread_mutex_lock(m) 108 #define mutex_unlock(m) if (__isthreaded) \ 109 _pthread_mutex_unlock(m) 110 #define mutex_trylock(m) (__isthreaded ? 0 : _pthread_mutex_trylock(m)) 111 112 #define cond_init(c, a, p) _pthread_cond_init(c, a) 113 #define cond_signal(m) if (__isthreaded) \ 114 _pthread_cond_signal(m) 115 #define cond_broadcast(m) if (__isthreaded) \ 116 _pthread_cond_broadcast(m) 117 #define cond_wait(c, m) if (__isthreaded) \ 118 _pthread_cond_wait(c, m) 119 120 #define rwlock_init(l, a) _pthread_rwlock_init(l, a) 121 #define rwlock_rdlock(l) if (__isthreaded) \ 122 _pthread_rwlock_rdlock(l) 123 #define rwlock_wrlock(l) if (__isthreaded) \ 124 _pthread_rwlock_wrlock(l) 125 #define rwlock_unlock(l) if (__isthreaded) \ 126 _pthread_rwlock_unlock(l) 127 128 #define thr_keycreate(k, d) _pthread_key_create(k, d) 129 #define thr_setspecific(k, p) _pthread_setspecific(k, p) 130 #define thr_getspecific(k) _pthread_getspecific(k) 131 #define thr_sigsetmask(f, n, o) _pthread_sigmask(f, n, o) 132 133 #define thr_once(o, i) _pthread_once(o, i) 134 #define thr_self() _pthread_self() 135 #define thr_exit(x) _pthread_exit(x) 136 #define thr_main() _pthread_main_np() 137