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)) 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)) 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 69 void set_y(int *y) 70 { 71 to_y = y; 72 fprintf(stderr, "%s: setting to_y=%p\n", __FUNCTION__, y); 73 } 74
