libexec/ld.elf_so/search.c

   1 /*      $NetBSD: search.c,v 1.24 2013/05/06 08:02:20 skrll 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 <sys/cdefs.h>
  40 #ifndef lint
  41 __RCSID("$NetBSD: search.c,v 1.24 2013/05/06 08:02:20 skrll Exp $");
  42 #endif /* not lint */
  43
  44 #include <err.h>
  45 #include <errno.h>
  46 #include <fcntl.h>
  47 #include <stdarg.h>
  48 #include <stdio.h>
  49 #include <stdlib.h>
  50 #include <string.h>
  51 #include <unistd.h>
  52 #include <sys/types.h>
  53 #include <sys/mman.h>
  54 #include <sys/stat.h>
  55 #include <dirent.h>
  56
  57 #include "debug.h"
  58 #include "rtld.h"
  59
  60 /*
  61  * Data declarations.
  62  */
  63 Search_Path    *_rtld_invalid_paths;
  64
  65 static Obj_Entry *_rtld_search_library_path(const char *, size_t,
  66     const char *, size_t, int);
  67
  68 static Obj_Entry *
  69 _rtld_search_library_path(const char *name, size_t namelen,
  70     const char *dir, size_t dirlen, int flags)
  71 {
  72         char pathname[MAXPATHLEN];
  73         size_t pathnamelen;
  74         Obj_Entry *obj;
  75         Search_Path *sp;
  76
  77         pathnamelen = dirlen + 1 + namelen;
  78         if (pathnamelen >= sizeof(pathname))
  79                 return NULL;
  80
  81         for (sp = _rtld_invalid_paths; sp != NULL; sp = sp->sp_next) {
  82                 if (sp->sp_pathlen == pathnamelen &&
  83                     sp->sp_path[dirlen] == '/' &&
  84                     !memcmp(name, sp->sp_path + dirlen + 1, namelen) &&
  85                     !memcmp(dir, sp->sp_path, dirlen)) {
  86                         return NULL;
  87                 }
  88         }
  89
  90         memcpy(pathname, dir, dirlen);
  91         pathname[dirlen] = '/';
  92         memcpy(pathname + dirlen + 1, name, namelen);
  93         pathname[pathnamelen] = '\0';
  94
  95         dbg(("  Trying \"%s\"", pathname));
  96         obj = _rtld_load_object(pathname, flags);
  97         if (obj == NULL) {
  98                 Search_Path *path;
  99
 100                 path = NEW(Search_Path);
 101                 path->sp_pathlen = pathnamelen;
 102                 path->sp_path = xstrdup(pathname);
 103                 path->sp_next = _rtld_invalid_paths;
 104                 _rtld_invalid_paths = path;
 105         }
 106         return obj;
 107 }
 108
 109 /*
 110  * Find the library with the given name, and return its full pathname.
 111  * The returned string is dynamically allocated.  Generates an error
 112  * message and returns NULL if the library cannot be found.
 113  *
 114  * If the second argument is non-NULL, then it refers to an already-
 115  * loaded shared object, whose library search path will be searched.
 116  */
 117 Obj_Entry *
 118 _rtld_load_library(const char *name, const Obj_Entry *refobj, int flags)
 119 {
 120         char tmperror[512], *tmperrorp;
 121         Search_Path *sp;
 122         const char *pathname;
 123         int namelen;
 124         Obj_Entry *obj;
 125
 126         if (strchr(name, '/') != NULL) {        /* Hard coded pathname */
 127                 if (name[0] != '/' && !_rtld_trust) {
 128                         _rtld_error(
 129                         "absolute pathname required for shared object \"%s\"",
 130                             name);
 131                         return NULL;
 132                 }
 133                 pathname = name;
 134                 goto found;
 135         }
 136         dbg((" Searching for \"%s\" (%p)", name, refobj));
 137
 138         tmperrorp = dlerror();
 139         if (tmperrorp != NULL) {
 140                 strncpy(tmperror, tmperrorp, sizeof tmperror);
 141                 tmperrorp = tmperror;
 142         }
 143
 144         namelen = strlen(name);
 145
 146         for (sp = _rtld_paths; sp != NULL; sp = sp->sp_next)
 147                 if ((obj = _rtld_search_library_path(name, namelen,
 148                     sp->sp_path, sp->sp_pathlen, flags)) != NULL)
 149                         goto pathfound;
 150
 151         if (refobj != NULL)
 152                 for (sp = refobj->rpaths; sp != NULL; sp = sp->sp_next)
 153                         if ((obj = _rtld_search_library_path(name,
 154                             namelen, sp->sp_path, sp->sp_pathlen, flags)) != NULL)
 155                                 goto pathfound;
 156
 157         for (sp = _rtld_default_paths; sp != NULL; sp = sp->sp_next)
 158                 if ((obj = _rtld_search_library_path(name, namelen,
 159                     sp->sp_path, sp->sp_pathlen, flags)) != NULL)
 160                         goto pathfound;
 161
 162         _rtld_error("Shared object \"%s\" not found", name);
 163         return NULL;
 164
 165 pathfound:
 166         /*
 167          * The library has been found, but it couldn't be loaded for some
 168          * reason.
 169          */
 170         if (obj == OBJ_ERR)
 171                 return NULL;
 172         /*
 173          * Successfully found a library; restore the dlerror state as it was
 174          * before _rtld_load_library() was called (any failed call to
 175          * _rtld_search_library_path() will set the dlerror state, but if the
 176          * library was eventually found, then the error state should not
 177          * change.
 178          */
 179         if (tmperrorp)
 180                 _rtld_error("%s", tmperror);
 181         else
 182                 (void)dlerror();
 183         return obj;
 184
 185 found:
 186         obj = _rtld_load_object(pathname, flags);
 187         if (obj == OBJ_ERR)
 188                 return NULL;
 189
 190         return obj;
 191 }
 192