Update.
[glibc.git] / linuxthreads / ptfork.c
blob564f8d7c756b8d2f94374a9e0fbe901d947d0694
1 /* Linuxthreads - a simple clone()-based implementation of Posix */
2 /* threads for Linux. */
3 /* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr) */
4 /* */
5 /* This program is free software; you can redistribute it and/or */
6 /* modify it under the terms of the GNU Library General Public License */
7 /* as published by the Free Software Foundation; either version 2 */
8 /* of the License, or (at your option) any later version. */
9 /* */
10 /* This program is distributed in the hope that it will be useful, */
11 /* but WITHOUT ANY WARRANTY; without even the implied warranty of */
12 /* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */
13 /* GNU Library General Public License for more details. */
15 /* The "atfork" stuff */
17 #include <errno.h>
18 #include <stddef.h>
19 #include <stdlib.h>
20 #include <unistd.h>
21 #include "pthread.h"
22 #include "internals.h"
23 #include <bits/libc-lock.h>
25 struct handler_list {
26 void (*handler)(void);
27 struct handler_list * next;
30 static pthread_mutex_t pthread_atfork_lock = PTHREAD_MUTEX_INITIALIZER;
31 static struct handler_list * pthread_atfork_prepare = NULL;
32 static struct handler_list * pthread_atfork_parent = NULL;
33 static struct handler_list * pthread_atfork_child = NULL;
35 static void pthread_insert_list(struct handler_list ** list,
36 void (*handler)(void),
37 struct handler_list * newlist,
38 int at_end)
40 if (handler == NULL) return;
41 if (at_end) {
42 while(*list != NULL) list = &((*list)->next);
44 newlist->handler = handler;
45 newlist->next = *list;
46 *list = newlist;
49 struct handler_list_block {
50 struct handler_list prepare, parent, child;
53 int __pthread_atfork(void (*prepare)(void),
54 void (*parent)(void),
55 void (*child)(void))
57 struct handler_list_block * block =
58 (struct handler_list_block *) malloc(sizeof(struct handler_list_block));
59 if (block == NULL) return ENOMEM;
60 pthread_mutex_lock(&pthread_atfork_lock);
61 /* "prepare" handlers are called in LIFO */
62 pthread_insert_list(&pthread_atfork_prepare, prepare, &block->prepare, 0);
63 /* "parent" handlers are called in FIFO */
64 pthread_insert_list(&pthread_atfork_parent, parent, &block->parent, 1);
65 /* "child" handlers are called in FIFO */
66 pthread_insert_list(&pthread_atfork_child, child, &block->child, 1);
67 pthread_mutex_unlock(&pthread_atfork_lock);
68 return 0;
70 strong_alias (__pthread_atfork, pthread_atfork)
72 static inline void pthread_call_handlers(struct handler_list * list)
74 for (/*nothing*/; list != NULL; list = list->next) (list->handler)();
77 extern int __libc_fork(void);
79 pid_t __fork(void)
81 pid_t pid;
83 pthread_mutex_lock(&pthread_atfork_lock);
85 pthread_call_handlers(pthread_atfork_prepare);
86 __pthread_once_fork_prepare();
87 __flockfilelist();
89 pid = __libc_fork();
91 if (pid == 0) {
92 __pthread_reset_main_thread();
94 __fresetlockfiles();
95 __pthread_once_fork_child();
96 pthread_call_handlers(pthread_atfork_child);
98 pthread_mutex_init(&pthread_atfork_lock, NULL);
99 } else {
100 __funlockfilelist();
101 __pthread_once_fork_parent();
102 pthread_call_handlers(pthread_atfork_parent);
104 pthread_mutex_unlock(&pthread_atfork_lock);
107 return pid;
110 weak_alias (__fork, fork);
112 pid_t __vfork(void)
114 return __fork();
116 weak_alias (__vfork, vfork);