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 <stdio.h>
30
31 /* This library is used to ensure that static C construction
32 * and destruction operate normally on dlopen() and dlclose().
33 *
34 * We use a global variable inside the DLL called "x"
35 * and initialize it to 1 in the static Foo_create constructor.
36 *
37 * The main program can access its address through dlsym()
38 * then later check that it was properly initialized.
39 */
40 int x = 0;
41
42 static void __attribute__((constructor))
Foo_create(void)43 Foo_create(void)
44 {
45 x = 1;
46 fprintf(stderr, "%s: setting x to 1\n", __FUNCTION__);
47 }
48
49 /* Similarly, the main program can provide the address of
50 * an integer, named "y", that will be set to 2 when the
51 * destructor is called on dlclose().
52 *
53 * This address must be provided through the "set_y" function
54 * that can also be resolved through dlsym() by the program.
55 */
56 static int *to_y = NULL;
57
58 static void __attribute__((destructor))
Foo_destroy(void)59 Foo_destroy(void)
60 {
61 if (to_y == NULL) {
62 fprintf(stderr, "%s: to_y uninitialized!!\n", __FUNCTION__);
63 *(int *)NULL = 0; // crash
64 }
65 *to_y = 2;
66 fprintf(stderr, "%s: setting y(%p) to 2!\n", __FUNCTION__, to_y);
67 }
68
set_y(int * y)69 void set_y(int *y)
70 {
71 to_y = y;
72 fprintf(stderr, "%s: setting to_y=%p\n", __FUNCTION__, y);
73 }
74