search.c revision 1.17 
1/*	$NetBSD: search.c,v 1.17 2003/07/24 10:12:26 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 <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 */
58Search_Path    *_rtld_invalid_paths;
59
60static Obj_Entry *_rtld_search_library_path(const char *, size_t,
61    const char *, size_t, int);
62
63static Obj_Entry *
64_rtld_search_library_path(const char *name, size_t namelen,
65    const char *dir, size_t dirlen, int mode)
66{
67	char *pathname;
68	size_t pathnamelen;
69	Obj_Entry *obj;
70	Search_Path *sp;
71
72	pathnamelen = dirlen + 1 + namelen;
73
74	for (sp = _rtld_invalid_paths; sp != NULL; sp = sp->sp_next) {
75		if (sp->sp_pathlen == pathnamelen &&
76		    !memcmp(name, sp->sp_path + dirlen + 1, namelen) &&
77		    !memcmp(dir, sp->sp_path, dirlen)) {
78			return NULL;
79		}
80	}
81
82	pathname = xmalloc(pathnamelen + 1);
83	(void)strncpy(pathname, dir, dirlen);
84	pathname[dirlen] = '/';
85	strcpy(pathname + dirlen + 1, name);
86
87	dbg(("  Trying \"%s\"", pathname));
88	obj = _rtld_load_object(pathname, mode);
89	if (obj == NULL) {
90		Search_Path *path;
91
92		path = NEW(Search_Path);
93		path->sp_pathlen = pathnamelen;
94		path->sp_path = pathname;
95		path->sp_next = _rtld_invalid_paths;
96		_rtld_invalid_paths = path;
97	}
98	return obj;
99}
100
101/*
102 * Find the library with the given name, and return its full pathname.
103 * The returned string is dynamically allocated.  Generates an error
104 * message and returns NULL if the library cannot be found.
105 *
106 * If the second argument is non-NULL, then it refers to an already-
107 * loaded shared object, whose library search path will be searched.
108 */
109Obj_Entry *
110_rtld_load_library(const char *name, const Obj_Entry *refobj, int mode)
111{
112	char tmperror[512], *tmperrorp;
113	Search_Path *sp;
114	char *pathname;
115	int namelen;
116	Obj_Entry *obj;
117
118	if (strchr(name, '/') != NULL) {	/* Hard coded pathname */
119		if (name[0] != '/' && !_rtld_trust) {
120			_rtld_error(
121			"absolute pathname required for shared object \"%s\"",
122			    name);
123			return NULL;
124		}
125		pathname = xstrdup(name);
126		goto found;
127	}
128	dbg((" Searching for \"%s\" (%p)", name, refobj));
129
130	tmperrorp = _rtld_dlerror();
131	if (tmperrorp != NULL) {
132		strncpy(tmperror, tmperrorp, sizeof tmperror);
133		tmperrorp = tmperror;
134	}
135
136	namelen = strlen(name);
137
138	for (sp = _rtld_paths; sp != NULL; sp = sp->sp_next)
139		if ((obj = _rtld_search_library_path(name, namelen,
140		    sp->sp_path, sp->sp_pathlen, mode)) != NULL)
141			goto pathfound;
142
143	if (refobj != NULL)
144		for (sp = refobj->rpaths; sp != NULL; sp = sp->sp_next)
145			if ((obj = _rtld_search_library_path(name,
146			    namelen, sp->sp_path, sp->sp_pathlen, mode)) != NULL)
147				goto pathfound;
148
149	for (sp = _rtld_default_paths; sp != NULL; sp = sp->sp_next)
150		if ((obj = _rtld_search_library_path(name, namelen,
151		    sp->sp_path, sp->sp_pathlen, mode)) != NULL)
152			goto pathfound;
153
154	_rtld_error("Shared object \"%s\" not found", name);
155	return NULL;
156
157pathfound:
158	/*
159	 * Successfully found a library; restore the dlerror state as it was
160	 * before _rtld_load_library() was called (any failed call to
161	 * _rtld_search_library_path() will set the dlerror state, but if the
162	 * library was eventually found, then the error state should not
163	 * change.
164	 */
165	if (tmperrorp)
166		_rtld_error("%s", tmperror);
167	else
168		(void)_rtld_dlerror();
169	return obj;
170
171found:
172	obj = _rtld_load_object(pathname, mode);
173	if (obj == NULL)
174		free(pathname);
175	return obj;
176}
177