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 * $FreeBSD$ 37 */ 38 39 /* 40 * Requirements: 41 * 42 * 1. The thread safe mechanism should be lightweight so the library can 43 * be used by non-threaded applications without unreasonable overhead. 44 * 45 * 2. There should be no dependency on a thread engine for non-threaded 46 * applications. 47 * 48 * 3. There should be no dependency on any particular thread engine. 49 * 50 * 4. The library should be able to be compiled without support for thread 51 * safety. 52 * 53 * 54 * Rationale: 55 * 56 * One approach for thread safety is to provide discrete versions of the 57 * library: one thread safe, the other not. The disadvantage of this is 58 * that libc is rather large, and two copies of a library which are 99%+ 59 * identical is not an efficent use of resources. 60 * 61 * Another approach is to provide a single thread safe library. However, 62 * it should not add significant run time or code size overhead to non- 63 * threaded applications. 64 * 65 * Since the NetBSD C library is used in other projects, it should be 66 * easy to replace the mutual exclusion primitives with ones provided by 67 * another system. Similarly, it should also be easy to remove all 68 * support for thread safety completely if the target environment does 69 * not support threads. 70 * 71 * 72 * Implementation Details: 73 * 74 * The mutex primitives used by the library (mutex_t, mutex_lock, etc.) 75 * are macros which expand to the cooresponding primitives provided by 76 * the thread engine or to nothing. The latter is used so that code is 77 * not unreasonably cluttered with #ifdefs when all thread safe support 78 * is removed. 79 * 80 * The mutex macros can be directly mapped to the mutex primitives from 81 * pthreads, however it should be reasonably easy to wrap another mutex 82 * implementation so it presents a similar interface. 83 * 84 * Stub implementations of the mutex functions are provided with *weak* 85 * linkage. These functions simply return success. When linked with a 86 * thread library (i.e. -lpthread), the functions will override the 87 * stubs. 88 */ 89 90 #include <pthread.h> 91 #include <pthread_np.h> 92 #include "libc_private.h" 93 94 #define mutex_t pthread_mutex_t 95 #define cond_t pthread_cond_t 96 #define rwlock_t pthread_rwlock_t 97 #define once_t pthread_once_t 98 99 #define thread_key_t pthread_key_t 100 #define MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER 101 #define RWLOCK_INITIALIZER PTHREAD_RWLOCK_INITIALIZER 102 #define ONCE_INITIALIZER PTHREAD_ONCE_INIT 103 104 #define mutex_init(m, a) _pthread_mutex_init(m, a) 105 #define mutex_lock(m) if (__isthreaded) \ 106 _pthread_mutex_lock(m) 107 #define mutex_unlock(m) if (__isthreaded) \ 108 _pthread_mutex_unlock(m) 109 #define mutex_trylock(m) (__isthreaded ? 0 : _pthread_mutex_trylock(m)) 110 111 #define cond_init(c, a, p) _pthread_cond_init(c, a) 112 #define cond_signal(m) if (__isthreaded) \ 113 _pthread_cond_signal(m) 114 #define cond_broadcast(m) if (__isthreaded) \ 115 _pthread_cond_broadcast(m) 116 #define cond_wait(c, m) if (__isthreaded) \ 117 _pthread_cond_wait(c, m) 118 119 #define rwlock_init(l, a) _pthread_rwlock_init(l, a) 120 #define rwlock_rdlock(l) if (__isthreaded) \ 121 _pthread_rwlock_rdlock(l) 122 #define rwlock_wrlock(l) if (__isthreaded) \ 123 _pthread_rwlock_wrlock(l) 124 #define rwlock_unlock(l) if (__isthreaded) \ 125 _pthread_rwlock_unlock(l) 126 127 #define thr_keycreate(k, d) _pthread_key_create(k, d) 128 #define thr_setspecific(k, p) _pthread_setspecific(k, p) 129 #define thr_getspecific(k) _pthread_getspecific(k) 130 #define thr_sigsetmask(f, n, o) _pthread_sigmask(f, n, o) 131 132 #define thr_once(o, i) _pthread_once(o, i) 133 #define thr_self() _pthread_self() 134 #define thr_exit(x) _pthread_exit(x) 135 #define thr_main() _pthread_main_np() 136