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
31#include "private/bionic_futex.h"
32#include "pthread_accessor.h"
33
34int pthread_join(pthread_t t, void** return_value) {
35  if (t == pthread_self()) {
36    return EDEADLK;
37  }
38
39  pid_t tid;
40  volatile int* tid_ptr;
41  {
42    pthread_accessor thread(t);
43    if (thread.get() == NULL) {
44      return ESRCH;
45    }
46
47    if ((thread->attr.flags & PTHREAD_ATTR_FLAG_DETACHED) != 0) {
48      return EINVAL;
49    }
50
51    if ((thread->attr.flags & PTHREAD_ATTR_FLAG_JOINED) != 0) {
52      return EINVAL;
53    }
54
55    // Okay, looks like we can signal our intention to join.
56    thread->attr.flags |= PTHREAD_ATTR_FLAG_JOINED;
57    tid = thread->tid;
58    tid_ptr = &thread->tid;
59  }
60
61  // We set the PTHREAD_ATTR_FLAG_JOINED flag with the lock held,
62  // so no one is going to remove this thread except us.
63
64  // Wait for the thread to actually exit, if it hasn't already.
65  while (*tid_ptr != 0) {
66    __futex_wait(tid_ptr, tid, NULL);
67  }
68
69  // Take the lock again so we can pull the thread's return value
70  // and remove the thread from the list.
71  pthread_accessor thread(t);
72
73  if (return_value) {
74    *return_value = thread->return_value;
75  }
76
77  _pthread_internal_remove_locked(thread.get());
78  return 0;
79}
80