1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 1997,98 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by J.T. Conklin. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 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. 18 * 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. 30 * 31 * $FreeBSD$ 32 */ 33 34 /* 35 * Requirements: 36 * 37 * 1. The thread safe mechanism should be lightweight so the library can 38 * be used by non-threaded applications without unreasonable overhead. 39 * 40 * 2. There should be no dependency on a thread engine for non-threaded 41 * applications. 42 * 43 * 3. There should be no dependency on any particular thread engine. 44 * 45 * 4. The library should be able to be compiled without support for thread 46 * safety. 47 * 48 * 49 * Rationale: 50 * 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. 55 * 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. 59 * 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. 65 * 66 * 67 * Implementation Details: 68 * 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 73 * is removed. 74 * 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. 78 * 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 82 * stubs. 83 */ 84 85 #include <pthread.h> 86 #include <pthread_np.h> 87 #include "libc_private.h" 88 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 93 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 98 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)) 105 106 #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) 113 114 #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) 121 122 #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) 126 127 #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() 131