1 /*- 2 * Copyright (c) 1998 John D. Polstra 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 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD: src/lib/libc/gen/dlfcn.c 217154 2011-01-08 17:13:43Z kib $ 27 */ 28 29 #include <sys/mman.h> 30 #include <dlfcn.h> 31 #include <link.h> 32 #include <stddef.h> 33 34 extern char **environ; 35 void _rtld_error(const char *, ...); 36 37 static char sorry[] = "Service unavailable"; 38 39 /* 40 * For ELF, the dynamic linker directly resolves references to its 41 * services to functions inside the dynamic linker itself. These 42 * weak-symbol stubs are necessary so that "ld" won't complain about 43 * undefined symbols. The stubs are executed only when the program is 44 * linked statically, or when a given service isn't implemented in the 45 * dynamic linker. They must return an error if called, and they must 46 * be weak symbols so that the dynamic linker can override them. 47 */ 48 49 #pragma weak _rtld_error 50 void 51 _rtld_error(const char *fmt __unused, ...) 52 { 53 } 54 55 #pragma weak dladdr 56 int 57 dladdr(const void *addr __unused, Dl_info *dlip __unused) 58 { 59 _rtld_error(sorry); 60 return 0; 61 } 62 63 #pragma weak dlclose 64 int 65 dlclose(void *handle __unused) 66 { 67 _rtld_error(sorry); 68 return -1; 69 } 70 71 #pragma weak dlerror 72 char * 73 dlerror(void) 74 { 75 return sorry; 76 } 77 78 #pragma weak dlopen 79 void * 80 dlopen(const char *name __unused, int mode __unused) 81 { 82 _rtld_error(sorry); 83 return NULL; 84 } 85 86 #pragma weak dlsym 87 void * 88 dlsym(void *handle __unused, const char *name __unused) 89 { 90 _rtld_error(sorry); 91 return NULL; 92 } 93 94 #pragma weak dlfunc 95 dlfunc_t 96 dlfunc(void * handle __unused, const char * name __unused) 97 { 98 _rtld_error(sorry); 99 return NULL; 100 } 101 102 #pragma weak dlvsym 103 void * 104 dlvsym(void *handle __unused,const char *name __unused, 105 const char *version __unused) 106 { 107 _rtld_error(sorry); 108 return NULL; 109 } 110 111 #pragma weak dlinfo 112 int 113 dlinfo(void *handle __unused, int request __unused, void *p __unused) 114 { 115 _rtld_error(sorry); 116 return 0; 117 } 118 119 __dso_hidden struct dl_phdr_info 120 build_phdr_info(void) 121 { 122 struct dl_phdr_info phdr_info; 123 Elf_Addr *sp; 124 Elf_Auxinfo *aux, *auxp; 125 size_t phent; 126 unsigned int i; 127 128 sp = (Elf_Addr *) environ; 129 while (*sp++ != 0) 130 ; 131 aux = (Elf_Auxinfo *) sp; 132 phent = 0; 133 memset (&phdr_info, 0, sizeof(phdr_info)); 134 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 135 switch (auxp->a_type) { 136 case AT_BASE: 137 phdr_info.dlpi_addr = (Elf_Addr) auxp->a_un.a_ptr; 138 break; 139 140 case AT_EXECPATH: 141 phdr_info.dlpi_name = (const char *) auxp->a_un.a_ptr; 142 break; 143 144 case AT_PHDR: 145 phdr_info.dlpi_phdr = (const Elf_Phdr *) auxp->a_un.a_ptr; 146 break; 147 148 case AT_PHENT: 149 phent = auxp->a_un.a_val; 150 break; 151 152 case AT_PHNUM: 153 phdr_info.dlpi_phnum = (Elf_Half) auxp->a_un.a_val; 154 break; 155 } 156 } 157 158 for (i = 0; i < phdr_info.dlpi_phnum; i++) 159 if (phdr_info.dlpi_phdr[i].p_type == PT_TLS) { 160 phdr_info.dlpi_tls_modid = 1; 161 phdr_info.dlpi_tls_data = 162 (void*) phdr_info.dlpi_phdr[i].p_vaddr; 163 } 164 165 return (phdr_info); 166 } 167 168 #pragma weak dl_iterate_phdr 169 int 170 dl_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void *), 171 void *data) 172 { 173 static seen = 0; 174 static struct dl_phdr_info phdr_info; 175 if (!seen) { 176 seen = 1; 177 phdr_info = build_phdr_info(); 178 } 179 180 return callback(&phdr_info, sizeof(phdr_info), data); 181 } 182 183 #pragma weak _rtld_addr_phdr 184 int 185 _rtld_addr_phdr(const void *addr, struct dl_phdr_info *phdr_info) 186 { 187 188 return (0); 189 } 190 191 #pragma weak _rtld_get_stack_prot 192 int 193 _rtld_get_stack_prot(void) 194 { 195 return (PROT_EXEC | PROT_READ | PROT_WRITE); 196 } 197