1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
|
/*
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <pthread.h>
#include <signal.h>
#include <stdlib.h>
#include <sys/mman.h>
#include "pthread_internal.h"
extern "C" __noreturn void _exit_with_stack_teardown(void*, size_t);
extern "C" __noreturn void __exit(int);
extern "C" int __set_tid_address(int*);
/* CAVEAT: our implementation of pthread_cleanup_push/pop doesn't support C++ exceptions
* and thread cancelation
*/
void __pthread_cleanup_push(__pthread_cleanup_t* c, __pthread_cleanup_func_t routine, void* arg) {
pthread_internal_t* thread = __get_thread();
c->__cleanup_routine = routine;
c->__cleanup_arg = arg;
c->__cleanup_prev = thread->cleanup_stack;
thread->cleanup_stack = c;
}
void __pthread_cleanup_pop(__pthread_cleanup_t* c, int execute) {
pthread_internal_t* thread = __get_thread();
thread->cleanup_stack = c->__cleanup_prev;
if (execute) {
c->__cleanup_routine(c->__cleanup_arg);
}
}
void pthread_exit(void* return_value) {
pthread_internal_t* thread = __get_thread();
thread->return_value = return_value;
// Call the cleanup handlers first.
while (thread->cleanup_stack) {
__pthread_cleanup_t* c = thread->cleanup_stack;
thread->cleanup_stack = c->__cleanup_prev;
c->__cleanup_routine(c->__cleanup_arg);
}
// Call the TLS destructors. It is important to do that before removing this
// thread from the global list. This will ensure that if someone else deletes
// a TLS key, the corresponding value will be set to NULL in this thread's TLS
// space (see pthread_key_delete).
pthread_key_clean_all();
if (thread->alternate_signal_stack != NULL) {
// Tell the kernel to stop using the alternate signal stack.
stack_t ss;
ss.ss_sp = NULL;
ss.ss_flags = SS_DISABLE;
sigaltstack(&ss, NULL);
// Free it.
munmap(thread->alternate_signal_stack, SIGSTKSZ);
thread->alternate_signal_stack = NULL;
}
// Keep track of what we need to know about the stack before we lose the pthread_internal_t.
void* stack_base = thread->attr.stack_base;
size_t stack_size = thread->attr.stack_size;
bool user_allocated_stack = ((thread->attr.flags & PTHREAD_ATTR_FLAG_USER_ALLOCATED_STACK) != 0);
pthread_mutex_lock(&g_thread_list_lock);
if ((thread->attr.flags & PTHREAD_ATTR_FLAG_DETACHED) != 0) {
// The thread is detached, so we can free the pthread_internal_t.
// First make sure that the kernel does not try to clear the tid field
// because we'll have freed the memory before the thread actually exits.
__set_tid_address(NULL);
_pthread_internal_remove_locked(thread);
} else {
// Make sure that the pthread_internal_t doesn't have stale pointers to a stack that
// will be unmapped after the exit call below.
if (!user_allocated_stack) {
thread->attr.stack_base = NULL;
thread->attr.stack_size = 0;
thread->tls = NULL;
}
// pthread_join is responsible for destroying the pthread_internal_t for non-detached threads.
// The kernel will futex_wake on the pthread_internal_t::tid field to wake pthread_join.
}
pthread_mutex_unlock(&g_thread_list_lock);
if (user_allocated_stack) {
// Cleaning up this thread's stack is the creator's responsibility, not ours.
__exit(0);
} else {
// We need to munmap the stack we're running on before calling exit.
// That's not something we can do in C.
// We don't want to take a signal after we've unmapped the stack.
// That's one last thing we can handle in C.
sigset_t mask;
sigfillset(&mask);
sigprocmask(SIG_SETMASK, &mask, NULL);
_exit_with_stack_teardown(stack_base, stack_size);
}
}
|
