1 /* $NetBSD: search.c,v 1.10 2000/07/27 10:44:39 kleink Exp $ */ 2 3 /* 4 * Copyright 1996 Matt Thomas <matt@3am-software.com> 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 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by John Polstra. 18 * 4. The name of the author may not be used to endorse or promote products 19 * derived from this software without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 /* 34 * Dynamic linker for ELF. 35 * 36 * John Polstra <jdp@polstra.com>. 37 */ 38 39 #include <err.h> 40 #include <errno.h> 41 #include <fcntl.h> 42 #include <stdarg.h> 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include <string.h> 46 #include <unistd.h> 47 #include <sys/types.h> 48 #include <sys/mman.h> 49 #include <sys/stat.h> 50 #include <dirent.h> 51 52 #include "debug.h" 53 #include "rtld.h" 54 55 /* 56 * Data declarations. 57 */ 58 static bool _rtld_check_library __P((const char *)); 59 static char *_rtld_search_library_path __P((const char *, size_t, const char *, 60 size_t)); 61 62 static bool 63 _rtld_check_library(pathname) 64 const char *pathname; 65 { 66 struct stat mystat; 67 Elf_Ehdr ehdr; 68 int fd; 69 70 if (stat(pathname, &mystat) == -1 || !S_ISREG(mystat.st_mode)) 71 return false; 72 73 if ((fd = open(pathname, O_RDONLY)) == -1) 74 return false; 75 76 if (read(fd, &ehdr, sizeof(ehdr)) != sizeof(ehdr)) 77 goto lose; 78 79 /* ELF_Ehdr.e_ident includes class */ 80 if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 || 81 ehdr.e_ident[EI_CLASS] != ELFCLASS) 82 goto lose; 83 84 switch (ehdr.e_machine) { 85 ELFDEFNNAME(MACHDEP_ID_CASES) 86 default: 87 goto lose; 88 } 89 90 if (ehdr.e_ident[EI_VERSION] != EV_CURRENT || 91 ehdr.e_version != EV_CURRENT || 92 ehdr.e_ident[EI_DATA] != ELFDEFNNAME(MACHDEP_ENDIANNESS) || 93 ehdr.e_type != ET_DYN) 94 goto lose; 95 96 close(fd); 97 return true; 98 99 lose: 100 close(fd); 101 return false; 102 } 103 104 105 static char * 106 _rtld_search_library_path(name, namelen, dir, dirlen) 107 const char *name; 108 size_t namelen; 109 const char *dir; 110 size_t dirlen; 111 { 112 char *pathname; 113 114 pathname = xmalloc(dirlen + 1 + namelen + 1); 115 (void)strncpy(pathname, dir, dirlen); 116 pathname[dirlen] = '/'; 117 strcpy(pathname + dirlen + 1, name); 118 119 dbg((" Trying \"%s\"", pathname)); 120 if (_rtld_check_library(pathname)) /* We found it */ 121 return pathname; 122 123 free(pathname); 124 return NULL; 125 } 126 127 /* 128 * Find the library with the given name, and return its full pathname. 129 * The returned string is dynamically allocated. Generates an error 130 * message and returns NULL if the library cannot be found. 131 * 132 * If the second argument is non-NULL, then it refers to an already- 133 * loaded shared object, whose library search path will be searched. 134 */ 135 char * 136 _rtld_find_library(name, refobj) 137 const char *name; 138 const Obj_Entry *refobj; 139 { 140 Search_Path *sp; 141 char *pathname; 142 int namelen; 143 144 if (strchr(name, '/') != NULL) { /* Hard coded pathname */ 145 if (name[0] != '/' && !_rtld_trust) { 146 _rtld_error( 147 "Absolute pathname required for shared object \"%s\"", 148 name); 149 return NULL; 150 } 151 #ifdef SVR4_LIBDIR 152 if (strncmp(name, SVR4_LIBDIR, SVR4_LIBDIRLEN) == 0 153 && name[SVR4_LIBDIRLEN] == '/') { /* In "/usr/lib" */ 154 /* 155 * Map hard-coded "/usr/lib" onto our ELF library 156 * directory. 157 */ 158 pathname = xmalloc(strlen(name) + LIBDIRLEN - 159 SVR4_LIBDIRLEN + 1); 160 (void)strcpy(pathname, LIBDIR); 161 (void)strcpy(pathname + LIBDIRLEN, name + 162 SVR4_LIBDIRLEN); 163 return pathname; 164 } 165 #endif /* SVR4_LIBDIR */ 166 return xstrdup(name); 167 } 168 dbg((" Searching for \"%s\" (%p)", name, refobj)); 169 170 namelen = strlen(name); 171 172 for (sp = _rtld_paths; sp != NULL; sp = sp->sp_next) 173 if ((pathname = _rtld_search_library_path(name, namelen, 174 sp->sp_path, sp->sp_pathlen)) != NULL) 175 return (pathname); 176 177 if (refobj != NULL) 178 for (sp = refobj->rpaths; sp != NULL; sp = sp->sp_next) 179 if ((pathname = _rtld_search_library_path(name, 180 namelen, sp->sp_path, sp->sp_pathlen)) != NULL) 181 return (pathname); 182 183 for (sp = _rtld_default_paths; sp != NULL; sp = sp->sp_next) 184 if ((pathname = _rtld_search_library_path(name, namelen, 185 sp->sp_path, sp->sp_pathlen)) != NULL) 186 return (pathname); 187 188 #if 0 189 if ((refobj != NULL && 190 (pathname = _rtld_search_library_path(name, 191 refobj->rpath)) != NULL) || 192 (pathname = _rtld_search_library_path(name, 193 ld_library_path)) != NULL 194 #ifdef SVR4_LIBDIR 195 LOSE ! 196 ||(pathname = _rtld_search_library_path(name, SVR4_LIBDIR)) != NULL 197 #endif 198 ) 199 return pathname; 200 #endif 201 202 _rtld_error("Shared object \"%s\" not found", name); 203 return NULL; 204 } 205