1 /*-
2  * Copyright (c) 2003-2007 Tim Kientzle
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(S) ``AS IS'' AND ANY EXPRESS OR
15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17  * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24  */
25 
26 #include "archive_platform.h"
27 __FBSDID("$FreeBSD: head/lib/libarchive/archive_read_disk_set_standard_lookup.c 201109 2009-12-28 03:30:31Z kientzle $");
28 
29 #ifdef HAVE_SYS_TYPES_H
30 #include <sys/types.h>
31 #endif
32 #ifdef HAVE_ERRNO_H
33 #include <errno.h>
34 #endif
35 #ifdef HAVE_GRP_H
36 #include <grp.h>
37 #endif
38 #ifdef HAVE_PWD_H
39 #include <pwd.h>
40 #endif
41 #ifdef HAVE_STDLIB_H
42 #include <stdlib.h>
43 #endif
44 #ifdef HAVE_STRING_H
45 #include <string.h>
46 #endif
47 
48 #include "archive.h"
49 
50 #if defined(_WIN32) && !defined(__CYGWIN__)
51 int
52 archive_read_disk_set_standard_lookup(struct archive *a)
53 {
54 	archive_set_error(a, -1, "Standard lookups not available on Windows");
55 	return (ARCHIVE_FATAL);
56 }
57 #else /* ! (_WIN32 && !__CYGWIN__) */
58 #define	name_cache_size 127
59 
60 static const char * const NO_NAME = "(noname)";
61 
62 struct name_cache {
63 	struct archive *archive;
64 	char   *buff;
65 	size_t  buff_size;
66 	int	probes;
67 	int	hits;
68 	size_t	size;
69 	struct {
70 		id_t id;
71 		const char *name;
72 	} cache[name_cache_size];
73 };
74 
75 static const char *	lookup_gname(void *, gid_t);
76 static const char *	lookup_uname(void *, uid_t);
77 static void	cleanup(void *);
78 static const char *	lookup_gname_helper(struct name_cache *, id_t gid);
79 static const char *	lookup_uname_helper(struct name_cache *, id_t uid);
80 
81 /*
82  * Installs functions that use getpwuid()/getgrgid()---along with
83  * a simple cache to accelerate such lookups---into the archive_read_disk
84  * object.  This is in a separate file because getpwuid()/getgrgid()
85  * can pull in a LOT of library code (including NIS/LDAP functions, which
86  * pull in DNS resolveers, etc).  This can easily top 500kB, which makes
87  * it inappropriate for some space-constrained applications.
88  *
89  * Applications that are size-sensitive may want to just use the
90  * real default functions (defined in archive_read_disk.c) that just
91  * use the uid/gid without the lookup.  Or define your own custom functions
92  * if you prefer.
93  */
94 int
95 archive_read_disk_set_standard_lookup(struct archive *a)
96 {
97 	struct name_cache *ucache = malloc(sizeof(struct name_cache));
98 	struct name_cache *gcache = malloc(sizeof(struct name_cache));
99 
100 	if (ucache == NULL || gcache == NULL) {
101 		archive_set_error(a, ENOMEM,
102 		    "Can't allocate uname/gname lookup cache");
103 		free(ucache);
104 		free(gcache);
105 		return (ARCHIVE_FATAL);
106 	}
107 
108 	memset(ucache, 0, sizeof(*ucache));
109 	ucache->archive = a;
110 	ucache->size = name_cache_size;
111 	memset(gcache, 0, sizeof(*gcache));
112 	gcache->archive = a;
113 	gcache->size = name_cache_size;
114 
115 	archive_read_disk_set_gname_lookup(a, gcache, lookup_gname, cleanup);
116 	archive_read_disk_set_uname_lookup(a, ucache, lookup_uname, cleanup);
117 
118 	return (ARCHIVE_OK);
119 }
120 
121 static void
122 cleanup(void *data)
123 {
124 	struct name_cache *cache = (struct name_cache *)data;
125 	size_t i;
126 
127 	if (cache != NULL) {
128 		for (i = 0; i < cache->size; i++) {
129 			if (cache->cache[i].name != NULL &&
130 			    cache->cache[i].name != NO_NAME)
131 				free((void *)(uintptr_t)cache->cache[i].name);
132 		}
133 		free(cache->buff);
134 		free(cache);
135 	}
136 }
137 
138 /*
139  * Lookup uid/gid from uname/gname, return NULL if no match.
140  */
141 static const char *
142 lookup_name(struct name_cache *cache,
143     const char * (*lookup_fn)(struct name_cache *, id_t), id_t id)
144 {
145 	const char *name;
146 	int slot;
147 
148 
149 	cache->probes++;
150 
151 	slot = id % cache->size;
152 	if (cache->cache[slot].name != NULL) {
153 		if (cache->cache[slot].id == id) {
154 			cache->hits++;
155 			if (cache->cache[slot].name == NO_NAME)
156 				return (NULL);
157 			return (cache->cache[slot].name);
158 		}
159 		if (cache->cache[slot].name != NO_NAME)
160 			free((void *)(uintptr_t)cache->cache[slot].name);
161 		cache->cache[slot].name = NULL;
162 	}
163 
164 	name = (lookup_fn)(cache, id);
165 	if (name == NULL) {
166 		/* Cache and return the negative response. */
167 		cache->cache[slot].name = NO_NAME;
168 		cache->cache[slot].id = id;
169 		return (NULL);
170 	}
171 
172 	cache->cache[slot].name = name;
173 	cache->cache[slot].id = id;
174 	return (cache->cache[slot].name);
175 }
176 
177 static const char *
178 lookup_uname(void *data, uid_t uid)
179 {
180 	struct name_cache *uname_cache = (struct name_cache *)data;
181 	return (lookup_name(uname_cache,
182 		    &lookup_uname_helper, (id_t)uid));
183 }
184 
185 #if HAVE_GETPWUID_R
186 static const char *
187 lookup_uname_helper(struct name_cache *cache, id_t id)
188 {
189 	struct passwd	pwent, *result;
190 	int r;
191 
192 	if (cache->buff_size == 0) {
193 		cache->buff_size = 256;
194 		cache->buff = malloc(cache->buff_size);
195 	}
196 	if (cache->buff == NULL)
197 		return (NULL);
198 	for (;;) {
199 		result = &pwent; /* Old getpwuid_r ignores last arg. */
200 		r = getpwuid_r((uid_t)id, &pwent,
201 			       cache->buff, cache->buff_size, &result);
202 		if (r == 0)
203 			break;
204 		if (r != ERANGE)
205 			break;
206 		/* ERANGE means our buffer was too small, but POSIX
207 		 * doesn't tell us how big the buffer should be, so
208 		 * we just double it and try again.  Because the buffer
209 		 * is kept around in the cache object, we shouldn't
210 		 * have to do this very often. */
211 		cache->buff_size *= 2;
212 		cache->buff = realloc(cache->buff, cache->buff_size);
213 		if (cache->buff == NULL)
214 			break;
215 	}
216 	if (r != 0) {
217 		archive_set_error(cache->archive, errno,
218 		    "Can't lookup user for id %d", (int)id);
219 		return (NULL);
220 	}
221 	if (result == NULL)
222 		return (NULL);
223 
224 	return strdup(result->pw_name);
225 }
226 #else
227 static const char *
228 lookup_uname_helper(struct name_cache *cache, id_t id)
229 {
230 	struct passwd	*result;
231 
232 	result = getpwuid((uid_t)id);
233 
234 	if (result == NULL)
235 		return (NULL);
236 
237 	return strdup(result->pw_name);
238 }
239 #endif
240 
241 static const char *
242 lookup_gname(void *data, gid_t gid)
243 {
244 	struct name_cache *gname_cache = (struct name_cache *)data;
245 	return (lookup_name(gname_cache,
246 		    &lookup_gname_helper, (id_t)gid));
247 }
248 
249 #if HAVE_GETGRGID_R
250 static const char *
251 lookup_gname_helper(struct name_cache *cache, id_t id)
252 {
253 	struct group	grent, *result;
254 	int r;
255 
256 	if (cache->buff_size == 0) {
257 		cache->buff_size = 256;
258 		cache->buff = malloc(cache->buff_size);
259 	}
260 	if (cache->buff == NULL)
261 		return (NULL);
262 	for (;;) {
263 		result = &grent; /* Old getgrgid_r ignores last arg. */
264 		r = getgrgid_r((gid_t)id, &grent,
265 			       cache->buff, cache->buff_size, &result);
266 		if (r == 0)
267 			break;
268 		if (r != ERANGE)
269 			break;
270 		/* ERANGE means our buffer was too small, but POSIX
271 		 * doesn't tell us how big the buffer should be, so
272 		 * we just double it and try again. */
273 		cache->buff_size *= 2;
274 		cache->buff = realloc(cache->buff, cache->buff_size);
275 		if (cache->buff == NULL)
276 			break;
277 	}
278 	if (r != 0) {
279 		archive_set_error(cache->archive, errno,
280 		    "Can't lookup group for id %d", (int)id);
281 		return (NULL);
282 	}
283 	if (result == NULL)
284 		return (NULL);
285 
286 	return strdup(result->gr_name);
287 }
288 #else
289 static const char *
290 lookup_gname_helper(struct name_cache *cache, id_t id)
291 {
292 	struct group	*result;
293 
294 	result = getgrgid((gid_t)id);
295 
296 	if (result == NULL)
297 		return (NULL);
298 
299 	return strdup(result->gr_name);
300 }
301 #endif
302 
303 #endif /* ! (_WIN32 && !__CYGWIN__) */
304