1 /* 2 * Copyright (C) 2008 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <errno.h> 30 #include <pthread.h> 31 32 struct atfork_t { 33 atfork_t* next; 34 atfork_t* prev; 35 36 void (*prepare)(void); 37 void (*child)(void); 38 void (*parent)(void); 39 }; 40 41 struct atfork_list_t { 42 atfork_t* first; 43 atfork_t* last; 44 }; 45 46 static pthread_mutex_t g_atfork_list_mutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER; 47 static atfork_list_t g_atfork_list = { NULL, NULL }; 48 49 void __bionic_atfork_run_prepare() { 50 // We lock the atfork list here, unlock it in the parent, and reset it in the child. 51 // This ensures that nobody can modify the handler array between the calls 52 // to the prepare and parent/child handlers. 53 // 54 // TODO: If a handler tries to mutate the list, they'll block. We should probably copy 55 // the list before forking, and have prepare, parent, and child all work on the consistent copy. 56 pthread_mutex_lock(&g_atfork_list_mutex); 57 58 // Call pthread_atfork() prepare handlers. POSIX states that the prepare 59 // handlers should be called in the reverse order of the parent/child 60 // handlers, so we iterate backwards. 61 for (atfork_t* it = g_atfork_list.last; it != NULL; it = it->prev) { 62 if (it->prepare != NULL) { 63 it->prepare(); 64 } 65 } 66 } 67 68 void __bionic_atfork_run_child() { 69 for (atfork_t* it = g_atfork_list.first; it != NULL; it = it->next) { 70 if (it->child != NULL) { 71 it->child(); 72 } 73 } 74 75 g_atfork_list_mutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER; 76 } 77 78 void __bionic_atfork_run_parent() { 79 for (atfork_t* it = g_atfork_list.first; it != NULL; it = it->next) { 80 if (it->parent != NULL) { 81 it->parent(); 82 } 83 } 84 85 pthread_mutex_unlock(&g_atfork_list_mutex); 86 } 87 88 int pthread_atfork(void (*prepare)(void), void (*parent)(void), void(*child)(void)) { 89 atfork_t* entry = reinterpret_cast<atfork_t*>(malloc(sizeof(atfork_t))); 90 if (entry == NULL) { 91 return ENOMEM; 92 } 93 94 entry->prepare = prepare; 95 entry->parent = parent; 96 entry->child = child; 97 98 pthread_mutex_lock(&g_atfork_list_mutex); 99 100 // Append 'entry' to the list. 101 entry->next = NULL; 102 entry->prev = g_atfork_list.last; 103 if (entry->prev != NULL) { 104 entry->prev->next = entry; 105 } 106 if (g_atfork_list.first == NULL) { 107 g_atfork_list.first = entry; 108 } 109 g_atfork_list.last = entry; 110 111 pthread_mutex_unlock(&g_atfork_list_mutex); 112 113 return 0; 114 } 115
