1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 /*
28 * Default backend-finder(s) for the name-service-switch routines.
29 * At present there is a single finder that uses dlopen() to do its thing.
30 *
31 * === Could also do a finder that includes db-name in filename
32 * === and one that does dlopen(0) to check in the executable
33 */
34
35 /* Allow our finder(s) to be overridden by user-supplied ones */
36
37 #pragma weak _nss_default_finders = nss_default_finders
38
39 #include "lint.h"
40 #include "mtlib.h"
41 #include <nss_common.h>
42 #include <dlfcn.h>
43 #include <stdio.h>
44 #include <stdlib.h>
45 #include <string.h>
46 #include <alloca.h>
47
48 /* === ? move these constants to a public header file ? */
49 static const int dlopen_version = 1;
50 #ifndef NSS_DLOPEN_FORMAT
51 #define NSS_DLOPEN_FORMAT "nss_%s.so.%d"
52 #endif
53 #ifndef NSS_DLSYM_FORMAT
54 #define NSS_DLSYM_FORMAT "_nss_%s_%s_constr"
55 #endif
56 static const char dlopen_format[] = NSS_DLOPEN_FORMAT;
57 static const char dlsym_format [] = NSS_DLSYM_FORMAT;
58 static const size_t format_maxlen = sizeof (dlsym_format) - 4;
59
60 static nss_backend_constr_t
SO_per_src_lookup(void * dummy __unused,const char * db_name,const char * src_name,void ** delete_privp)61 SO_per_src_lookup(void *dummy __unused, const char *db_name,
62 const char *src_name, void **delete_privp)
63 {
64 char *name;
65 void *dlhandle;
66 void *sym;
67 size_t len;
68 nss_backend_constr_t res = 0;
69
70 len = format_maxlen + strlen(db_name) + strlen(src_name);
71 name = alloca(len);
72 (void) sprintf(name, dlopen_format, src_name, dlopen_version);
73 if ((dlhandle = dlopen(name, RTLD_LAZY)) != 0) {
74 (void) sprintf(name, dlsym_format, src_name, db_name);
75 if ((sym = dlsym(dlhandle, name)) == 0) {
76 (void) dlclose(dlhandle);
77 } else {
78 *delete_privp = dlhandle;
79 res = (nss_backend_constr_t)sym;
80 }
81 }
82 return (res);
83 }
84
85 static void
SO_per_src_delete(void * delete_priv,nss_backend_constr_t dummy __unused)86 SO_per_src_delete(void *delete_priv, nss_backend_constr_t dummy __unused)
87 {
88 (void) dlclose(delete_priv);
89 }
90
91 static nss_backend_finder_t SO_per_src = {
92 SO_per_src_lookup,
93 SO_per_src_delete,
94 0,
95 0
96 };
97
98 nss_backend_finder_t *nss_default_finders = &SO_per_src;
99