fork.cpp revision 7086ad6919feb2415c6027163f5c63323bcca27c 
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 <unistd.h>
30#include <sys/syscall.h>
31
32#include "pthread_internal.h"
33
34#define FORK_FLAGS (CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID | SIGCHLD)
35
36int fork() {
37  __bionic_atfork_run_prepare();
38
39  pthread_internal_t* self = __get_thread();
40
41  // Remember the parent pid and invalidate the cached value while we fork.
42  pid_t parent_pid = self->invalidate_cached_pid();
43
44#if defined(__x86_64__) // sys_clone's last two arguments are flipped on x86-64.
45  int result = syscall(__NR_clone, FORK_FLAGS, NULL, NULL, &(self->tid), NULL);
46#else
47  int result = syscall(__NR_clone, FORK_FLAGS, NULL, NULL, NULL, &(self->tid));
48#endif
49  if (result == 0) {
50    self->set_cached_pid(gettid());
51    __bionic_atfork_run_child();
52  } else {
53    self->set_cached_pid(parent_pid);
54    __bionic_atfork_run_parent();
55  }
56  return result;
57}
58