dlfcn_elf.c revision 1.10
1 /* $NetBSD: dlfcn_elf.c,v 1.10 2011/06/25 05:45:11 nonaka Exp $ */ 2 3 /* 4 * Copyright (c) 2000 Takuya SHIOZAKI 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include <sys/cdefs.h> 29 #if defined(LIBC_SCCS) && !defined(lint) 30 __RCSID("$NetBSD: dlfcn_elf.c,v 1.10 2011/06/25 05:45:11 nonaka Exp $"); 31 #endif /* LIBC_SCCS and not lint */ 32 33 #include "namespace.h" 34 #include <sys/atomic.h> 35 #include <elf.h> 36 #include <errno.h> 37 #include <string.h> 38 #include <stdbool.h> 39 40 #undef dlopen 41 #undef dlclose 42 #undef dlsym 43 #undef dlerror 44 #undef dladdr 45 #undef dfinfo 46 47 #define dlopen ___dlopen 48 #define dlclose ___dlclose 49 #define dlsym ___dlsym 50 #define dlvsym ___dlvsym 51 #define dlerror ___dlerror 52 #define dladdr ___dladdr 53 #define dlinfo ___dlinfo 54 #define dl_iterate_phdr ___dl_iterate_phdr 55 56 #define ELFSIZE ARCH_ELFSIZE 57 #include "rtld.h" 58 59 #ifdef __weak_alias 60 __weak_alias(dlopen,___dlopen) 61 __weak_alias(dlclose,___dlclose) 62 __weak_alias(dlsym,___dlsym) 63 __weak_alias(dlvsym,___dlvsym) 64 __weak_alias(dlerror,___dlerror) 65 __weak_alias(dladdr,___dladdr) 66 __weak_alias(dlinfo,___dlinfo) 67 __weak_alias(dl_iterate_phdr,___dl_iterate_phdr) 68 69 __weak_alias(__dlopen,___dlopen) 70 __weak_alias(__dlclose,___dlclose) 71 __weak_alias(__dlsym,___dlsym) 72 __weak_alias(__dlvsym,___dlvsym) 73 __weak_alias(__dlerror,___dlerror) 74 __weak_alias(__dladdr,___dladdr) 75 __weak_alias(__dlinfo,___dlinfo) 76 __weak_alias(__dl_iterate_phdr,___dl_iterate_phdr) 77 #endif 78 79 /* 80 * For ELF, the dynamic linker directly resolves references to its 81 * services to functions inside the dynamic linker itself. These 82 * weak-symbol stubs are necessary so that "ld" won't complain about 83 * undefined symbols. The stubs are executed only when the program is 84 * linked statically, or when a given service isn't implemented in the 85 * dynamic linker. They must return an error if called, and they must 86 * be weak symbols so that the dynamic linker can override them. 87 */ 88 89 static char dlfcn_error[] = "Service unavailable"; 90 91 /*ARGSUSED*/ 92 void * 93 dlopen(const char *name, int mode) 94 { 95 96 return NULL; 97 } 98 99 /*ARGSUSED*/ 100 int 101 dlclose(void *fd) 102 { 103 104 return -1; 105 } 106 107 /*ARGSUSED*/ 108 void * 109 dlsym(void *handle, const char *name) 110 { 111 112 return NULL; 113 } 114 115 /*ARGSUSED*/ 116 void * 117 dlvsym(void *handle, const char *name, const char *version) 118 { 119 120 return NULL; 121 } 122 123 /*ARGSUSED*/ 124 __aconst char * 125 dlerror() 126 { 127 128 return dlfcn_error; 129 } 130 131 /*ARGSUSED*/ 132 int 133 dladdr(const void *addr, Dl_info *dli) 134 { 135 136 return 0; 137 } 138 139 /*ARGSUSED*/ 140 int 141 dlinfo(void *handle, int req, void *v) 142 { 143 144 return -1; 145 } 146 147 static const char *dlpi_name; 148 static Elf_Addr dlpi_addr; 149 static const Elf_Phdr *dlpi_phdr; 150 static Elf_Half dlpi_phnum; 151 152 /* 153 * Declare as common symbol to allow new libc with older binaries to 154 * not trigger an undefined reference. 155 */ 156 extern __dso_hidden void *__auxinfo; 157 158 static void 159 dl_iterate_phdr_setup(void) 160 { 161 const AuxInfo *aux; 162 163 if (__auxinfo == NULL) 164 return; 165 166 for (aux = __auxinfo; aux->a_type != AT_NULL; ++aux) { 167 switch (aux->a_type) { 168 case AT_BASE: 169 dlpi_addr = aux->a_v; 170 break; 171 case AT_PHDR: 172 dlpi_phdr = (void *)aux->a_v; 173 break; 174 case AT_PHNUM: 175 dlpi_phnum = aux->a_v; 176 break; 177 case AT_SUN_EXECNAME: 178 dlpi_name = (void *)aux->a_v; 179 break; 180 } 181 } 182 } 183 184 /*ARGSUSED*/ 185 int 186 dl_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void *), 187 void *data) 188 { 189 static bool setup_done; 190 struct dl_phdr_info phdr_info; 191 192 if (__auxinfo == NULL) 193 return EOPNOTSUPP; 194 195 if (!setup_done) { 196 /* 197 * This can race on the first call to dl_iterate_phdr. 198 * dl_iterate_phdr_setup only touches field of pointer size 199 * and smaller and such stores are atomic. 200 */ 201 dl_iterate_phdr_setup(); 202 membar_producer(); 203 setup_done = true; 204 } 205 206 memset(&phdr_info, 0, sizeof(phdr_info)); 207 phdr_info.dlpi_addr = dlpi_addr; 208 phdr_info.dlpi_phdr = dlpi_phdr; 209 phdr_info.dlpi_phnum = dlpi_phnum; 210 phdr_info.dlpi_name = dlpi_name; 211 212 return callback(&phdr_info, sizeof(phdr_info), data); 213 } 214
Indexes created Fri Sep 26 20:09:58 GMT 2025