1 /* $OpenBSD: atexit.c,v 1.14 2007/09/05 20:47:47 chl Exp $ */ 2 /* 3 * Copyright (c) 2002 Daniel Hartmeier 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 10 * - Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * - Redistributions in binary form must reproduce the above 13 * copyright notice, this list of conditions and the following 14 * disclaimer in the documentation and/or other materials provided 15 * with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 18 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 19 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 20 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 21 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 23 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 24 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 25 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 27 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28 * POSSIBILITY OF SUCH DAMAGE. 29 * 30 */ 31 32 #include <sys/types.h> 33 #include <sys/mman.h> 34 #include <stdlib.h> 35 #include <string.h> 36 #include <unistd.h> 37 #include "atexit.h" 38 #include "thread_private.h" 39 40 int __atexit_invalid = 1; 41 struct atexit *__atexit; 42 43 /* 44 * Function pointers are stored in a linked list of pages. The list 45 * is initially empty, and pages are allocated on demand. The first 46 * function pointer in the first allocated page (the last one in 47 * the linked list) was reserved for the cleanup function. 48 * TODO: switch to the regular FreeBSD/NetBSD atexit implementation. 49 * 50 * Outside the following functions, all pages are mprotect()'ed 51 * to prevent unintentional/malicious corruption. 52 */ 53 54 /* 55 * Register a function to be performed at exit or when a shared object 56 * with the given dso handle is unloaded dynamically. Also used as 57 * the backend for atexit(). For more info on this API, see: 58 * 59 * http://www.codesourcery.com/cxx-abi/abi.html#dso-dtor 60 */ 61 int 62 __cxa_atexit(void (*func)(void *), void *arg, void *dso) 63 { 64 struct atexit *p = __atexit; 65 struct atexit_fn *fnp; 66 int pgsize = getpagesize(); 67 int ret = -1; 68 69 if (pgsize < (int)sizeof(*p)) 70 return (-1); 71 _ATEXIT_LOCK(); 72 p = __atexit; 73 if (p != NULL) { 74 if (p->ind + 1 >= p->max) 75 p = NULL; 76 else if (mprotect(p, pgsize, PROT_READ | PROT_WRITE)) 77 goto unlock; 78 } 79 if (p == NULL) { 80 p = mmap(NULL, pgsize, PROT_READ | PROT_WRITE, 81 MAP_ANON | MAP_PRIVATE, -1, 0); 82 if (p == MAP_FAILED) 83 goto unlock; 84 if (__atexit == NULL) { 85 memset(&p->fns[0], 0, sizeof(p->fns[0])); 86 p->ind = 1; 87 } else 88 p->ind = 0; 89 p->max = (pgsize - ((char *)&p->fns[0] - (char *)p)) / 90 sizeof(p->fns[0]); 91 p->next = __atexit; 92 __atexit = p; 93 if (__atexit_invalid) 94 __atexit_invalid = 0; 95 } 96 fnp = &p->fns[p->ind++]; 97 fnp->fn_ptr.cxa_func = func; 98 fnp->fn_arg = arg; 99 fnp->fn_dso = dso; 100 if (mprotect(p, pgsize, PROT_READ)) 101 goto unlock; 102 ret = 0; 103 unlock: 104 _ATEXIT_UNLOCK(); 105 return (ret); 106 } 107 108 /* 109 * Call all handlers registered with __cxa_atexit() for the shared 110 * object owning 'dso'. 111 * Note: if 'dso' is NULL, then all remaining handlers are called. 112 */ 113 void 114 __cxa_finalize(void *dso) 115 { 116 struct atexit *p, *q; 117 struct atexit_fn fn; 118 int n, pgsize = getpagesize(); 119 static int call_depth; 120 121 if (__atexit_invalid) 122 return; 123 124 _ATEXIT_LOCK(); 125 call_depth++; 126 127 for (p = __atexit; p != NULL; p = p->next) { 128 for (n = p->ind; --n >= 0;) { 129 if (p->fns[n].fn_ptr.cxa_func == NULL) 130 continue; /* already called */ 131 if (dso != NULL && dso != p->fns[n].fn_dso) 132 continue; /* wrong DSO */ 133 134 /* 135 * Mark handler as having been already called to avoid 136 * dupes and loops, then call the appropriate function. 137 */ 138 fn = p->fns[n]; 139 if (mprotect(p, pgsize, PROT_READ | PROT_WRITE) == 0) { 140 p->fns[n].fn_ptr.cxa_func = NULL; 141 mprotect(p, pgsize, PROT_READ); 142 } 143 _ATEXIT_UNLOCK(); 144 #if ANDROID 145 /* it looks like we should always call the function 146 * with an argument, even if dso is not NULL. Otherwise 147 * static destructors will not be called properly on 148 * the ARM. 149 */ 150 (*fn.fn_ptr.cxa_func)(fn.fn_arg); 151 #else /* !ANDROID */ 152 if (dso != NULL) 153 (*fn.fn_ptr.cxa_func)(fn.fn_arg); 154 else 155 (*fn.fn_ptr.std_func)(); 156 #endif /* !ANDROID */ 157 _ATEXIT_LOCK(); 158 } 159 } 160 161 /* 162 * If called via exit(), unmap the pages since we have now run 163 * all the handlers. We defer this until calldepth == 0 so that 164 * we don't unmap things prematurely if called recursively. 165 */ 166 if (dso == NULL && --call_depth == 0) { 167 for (p = __atexit; p != NULL; ) { 168 q = p; 169 p = p->next; 170 munmap(q, pgsize); 171 } 172 __atexit = NULL; 173 } 174 _ATEXIT_UNLOCK(); 175 } 176
