src/pthread_atfork.c

   1 /*
   2  * Copyright (c) 1999, 2012 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #include "internal.h"
  25
  26 #include <mach/mach_init.h>
  27 #include <mach/mach_vm.h>
  28 #include <platform/compat.h>
  29
  30 int
  31 pthread_atfork(void (*prepare)(void), void (*parent)(void), void (*child)(void))
  32 {
  33         int res = 0;
  34         size_t idx;
  35         pthread_globals_t globals = _pthread_globals();
  36
  37         _PTHREAD_LOCK(globals->pthread_atfork_lock);
  38         idx = globals->atfork_count++;
  39
  40         if (idx == 0) {
  41                 // Initialize pointer to inline storage.
  42                 globals->atfork = globals->atfork_storage;
  43         } else if (idx == PTHREAD_ATFORK_INLINE_MAX) {
  44                 // Migrate to out-of-line storage.
  45                 kern_return_t kr;
  46                 mach_vm_address_t storage = 0;
  47                 mach_vm_size_t size = PTHREAD_ATFORK_MAX * sizeof(struct pthread_atfork_entry);
  48                 _PTHREAD_UNLOCK(globals->pthread_atfork_lock);
  49                 kr = mach_vm_map(mach_task_self(),
  50                                  &storage,
  51                                  size,
  52                                  vm_page_size - 1,
  53                                  VM_MAKE_TAG(VM_MEMORY_OS_ALLOC_ONCE)| VM_FLAGS_ANYWHERE,
  54                                  MEMORY_OBJECT_NULL,
  55                                  0,
  56                                  FALSE,
  57                                  VM_PROT_DEFAULT,
  58                                  VM_PROT_ALL,
  59                                  VM_INHERIT_DEFAULT);
  60                 _PTHREAD_LOCK(globals->pthread_atfork_lock);
  61                 if (kr == KERN_SUCCESS) {
  62                         if (globals->atfork == globals->atfork_storage) {
  63                                 globals->atfork = storage;
  64                                 memmove(globals->atfork, globals->atfork_storage, sizeof(globals->atfork_storage));
  65                                 bzero(globals->atfork_storage, sizeof(globals->atfork_storage));
  66                         } else {
  67                                 // Another thread did vm_map first.
  68                                 _PTHREAD_UNLOCK(globals->pthread_atfork_lock);
  69                                 mach_vm_deallocate(mach_task_self(), storage, size);
  70                                 _PTHREAD_LOCK(globals->pthread_atfork_lock);
  71                         }
  72                 } else {
  73                         res = ENOMEM;
  74                 }
  75         } else if (idx >= PTHREAD_ATFORK_MAX) {
  76                 res = ENOMEM;
  77         }
  78
  79         if (res == 0) {
  80                 struct pthread_atfork_entry *e = &globals->atfork[idx];
  81                 e->prepare = prepare;
  82                 e->parent = parent;
  83                 e->child = child;
  84         }
  85         _PTHREAD_UNLOCK(globals->pthread_atfork_lock);
  86
  87         return res;
  88 }
  89
  90 // Called before the fork(2) system call is made in the parent process.
  91 // Iterate pthread_atfork prepare handlers.
  92 // Called first in libSystem_atfork_prepare().
  93 void
  94 _pthread_atfork_prepare_handlers(void)
  95 {
  96         pthread_globals_t globals = _pthread_globals();
  97
  98         _PTHREAD_LOCK(globals->pthread_atfork_lock);
  99         size_t idx;
 100         for (idx = globals->atfork_count; idx > 0; --idx) {
 101                 struct pthread_atfork_entry *e = &globals->atfork[idx-1];
 102                 if (e->prepare != NULL) {
 103                         e->prepare();
 104                 }
 105         }
 106 }
 107
 108 // Take pthread-internal locks.
 109 // Called last in libSystem_atfork_prepare().
 110 void
 111 _pthread_atfork_prepare(void)
 112 {
 113         pthread_globals_t globals = _pthread_globals();
 114
 115         _PTHREAD_LOCK(globals->psaved_self_global_lock);
 116         globals->psaved_self = pthread_self();
 117         _PTHREAD_LOCK(globals->psaved_self->lock);
 118 }
 119
 120 // Called after the fork(2) system call returns to the parent process.
 121 // Release pthread-internal locks
 122 // Called first in libSystem_atfork_parent().
 123 void
 124 _pthread_atfork_parent(void)
 125 {
 126         pthread_globals_t globals = _pthread_globals();
 127
 128         _PTHREAD_UNLOCK(globals->psaved_self->lock);
 129         _PTHREAD_UNLOCK(globals->psaved_self_global_lock);
 130 }
 131
 132 // Iterate pthread_atfork parent handlers.
 133 // Called last in libSystem_atfork_parent().
 134 void
 135 _pthread_atfork_parent_handlers(void)
 136 {
 137         pthread_globals_t globals = _pthread_globals();
 138
 139         size_t idx;
 140         for (idx = 0; idx < globals->atfork_count; ++idx) {
 141                 struct pthread_atfork_entry *e = &globals->atfork[idx];
 142                 if (e->parent != NULL) {
 143                         e->parent();
 144                 }
 145         }
 146         _PTHREAD_UNLOCK(globals->pthread_atfork_lock);
 147 }
 148
 149 // Called after the fork(2) system call returns to the new child process.
 150 // Clean up data structures of other threads which no longer exist in the child.
 151 // Make the current thread the main thread.
 152 // Called first in libSystem_atfork_child() (after _dyld_fork_child)
 153 void
 154 _pthread_atfork_child(void)
 155 {
 156         pthread_globals_t globals = _pthread_globals();
 157         _PTHREAD_LOCK_INIT(globals->psaved_self_global_lock);
 158         __is_threaded = 0;
 159         _pthread_main_thread_postfork_init(globals->psaved_self);
 160
 161         struct _pthread_registration_data registration_data;
 162         _pthread_bsdthread_init(&registration_data);
 163 }
 164
 165 // Iterate pthread_atfork child handlers.
 166 // Called last in libSystem_atfork_child().
 167 void
 168 _pthread_atfork_child_handlers(void)
 169 {
 170         pthread_globals_t globals = _pthread_globals();
 171         size_t idx;
 172         for (idx = 0; idx < globals->atfork_count; ++idx) {
 173                 struct pthread_atfork_entry *e = &globals->atfork[idx];
 174                 if (e->child != NULL) {
 175                         e->child();
 176                 }
 177         }
 178         _PTHREAD_LOCK_INIT(globals->pthread_atfork_lock);
 179 }
 180
 181 // Preserve legacy symbols for older iOS simulators
 182 void
 183 _pthread_fork_prepare(void)
 184 {
 185         _pthread_atfork_prepare_handlers();
 186         _pthread_atfork_prepare();
 187 }
 188
 189 void
 190 _pthread_fork_parent(void)
 191 {
 192         _pthread_atfork_parent();
 193         _pthread_atfork_parent_handlers();
 194 }
 195
 196 void
 197 _pthread_fork_child(void)
 198 {
 199         _pthread_atfork_child();
 200 }
 201
 202 void
 203 _pthread_fork_child_postinit(void)
 204 {
 205         _pthread_atfork_child_handlers();
 206 }