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
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
|
/* $OpenBSD: atexit.c,v 1.20 2014/07/11 09:51:37 kettenis Exp $ */
/*
* Copyright (c) 2002 Daniel Hartmeier
* 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 HOLDERS 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 "atexit.h"
#include <pthread.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/prctl.h>
#include <sys/types.h>
static pthread_mutex_t g_atexit_lock = PTHREAD_MUTEX_INITIALIZER;
#define _ATEXIT_LOCK() pthread_mutex_lock(&g_atexit_lock)
#define _ATEXIT_UNLOCK() pthread_mutex_unlock(&g_atexit_lock)
struct atexit {
struct atexit *next; /* next in list */
int ind; /* next index in this table */
int max; /* max entries >= ATEXIT_SIZE */
struct atexit_fn {
void (*fn_ptr)(void *);
void *fn_arg; /* argument for CXA callback */
void *fn_dso; /* shared module handle */
} fns[1]; /* the table itself */
};
static struct atexit *__atexit;
static int restartloop;
/* BEGIN android-changed: __unregister_atfork is used by __cxa_finalize */
extern void __unregister_atfork(void* dso);
/* END android-changed */
/*
* Function pointers are stored in a linked list of pages. The list
* is initially empty, and pages are allocated on demand. The first
* function pointer in the first allocated page (the last one in
* the linked list) is reserved for the cleanup function.
*
* Outside the following functions, all pages are mprotect()'ed
* to prevent unintentional/malicious corruption.
*/
/*
* Register a function to be performed at exit or when a shared object
* with the given dso handle is unloaded dynamically. Also used as
* the backend for atexit(). For more info on this API, see:
*
* http://www.codesourcery.com/cxx-abi/abi.html#dso-dtor
*/
int
__cxa_atexit(void (*func)(void *), void *arg, void *dso)
{
struct atexit_fn *fnp;
size_t pgsize = getpagesize();
int ret = -1;
if (pgsize < sizeof(struct atexit))
return (-1);
_ATEXIT_LOCK();
struct atexit *p = __atexit;
if (p != NULL) {
if (p->ind + 1 >= p->max)
p = NULL;
else if (mprotect(p, pgsize, PROT_READ | PROT_WRITE))
goto unlock;
}
if (p == NULL) {
p = mmap(NULL, pgsize, PROT_READ | PROT_WRITE,
MAP_ANON | MAP_PRIVATE, -1, 0);
if (p == MAP_FAILED)
goto unlock;
/* BEGIN android-changed */
prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, p, pgsize,
"atexit handlers");
/* END android-changed */
if (__atexit == NULL) {
memset(&p->fns[0], 0, sizeof(p->fns[0]));
p->ind = 1;
} else
p->ind = 0;
p->max = (pgsize - ((char *)&p->fns[0] - (char *)p)) /
sizeof(p->fns[0]);
p->next = __atexit;
__atexit = p;
}
fnp = &p->fns[p->ind++];
fnp->fn_ptr = func;
fnp->fn_arg = arg;
fnp->fn_dso = dso;
if (mprotect(p, pgsize, PROT_READ))
goto unlock;
restartloop = 1;
ret = 0;
unlock:
_ATEXIT_UNLOCK();
return (ret);
}
/*
* Call all handlers registered with __cxa_atexit() for the shared
* object owning 'dso'.
* Note: if 'dso' is NULL, then all remaining handlers are called.
*/
void
__cxa_finalize(void *dso)
{
struct atexit *p, *q;
struct atexit_fn fn;
int n, pgsize = getpagesize();
static int call_depth;
_ATEXIT_LOCK();
call_depth++;
restart:
restartloop = 0;
for (p = __atexit; p != NULL; p = p->next) {
for (n = p->ind; --n >= 0;) {
if (p->fns[n].fn_ptr == NULL)
continue; /* already called */
if (dso != NULL && dso != p->fns[n].fn_dso)
continue; /* wrong DSO */
/*
* Mark handler as having been already called to avoid
* dupes and loops, then call the appropriate function.
*/
fn = p->fns[n];
if (mprotect(p, pgsize, PROT_READ | PROT_WRITE) == 0) {
p->fns[n].fn_ptr = NULL;
mprotect(p, pgsize, PROT_READ);
}
_ATEXIT_UNLOCK();
(*fn.fn_ptr)(fn.fn_arg);
_ATEXIT_LOCK();
if (restartloop)
goto restart;
}
}
call_depth--;
/*
* If called via exit(), unmap the pages since we have now run
* all the handlers. We defer this until calldepth == 0 so that
* we don't unmap things prematurely if called recursively.
*/
if (dso == NULL && call_depth == 0) {
for (p = __atexit; p != NULL; ) {
q = p;
p = p->next;
munmap(q, pgsize);
}
__atexit = NULL;
}
_ATEXIT_UNLOCK();
/* If called via exit(), flush output of all open files. */
if (dso == NULL) {
fflush(NULL);
}
/* BEGIN android-changed: call __unregister_atfork if dso is not null */
if (dso != NULL) {
__unregister_atfork(dso);
}
/* END android-changed */
}
|
