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_write_disk_set_standard_lookup.c 201083 2009-12-28 02:09:57Z 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 #include "archive_private.h"
50 #include "archive_read_private.h"
51 #include "archive_write_disk_private.h"
52
53 struct bucket {
54 char *name;
55 int hash;
56 id_t id;
57 };
58
59 static const size_t cache_size = 127;
60 static unsigned int hash(const char *);
61 static int64_t lookup_gid(void *, const char *uname, int64_t);
62 static int64_t lookup_uid(void *, const char *uname, int64_t);
63 static void cleanup(void *);
64
65 /*
66 * Installs functions that use getpwnam()/getgrnam()---along with
67 * a simple cache to accelerate such lookups---into the archive_write_disk
68 * object. This is in a separate file because getpwnam()/getgrnam()
69 * can pull in a LOT of library code (including NIS/LDAP functions, which
70 * pull in DNS resolvers, etc). This can easily top 500kB, which makes
71 * it inappropriate for some space-constrained applications.
72 *
73 * Applications that are size-sensitive may want to just use the
74 * real default functions (defined in archive_write_disk.c) that just
75 * use the uid/gid without the lookup. Or define your own custom functions
76 * if you prefer.
77 *
78 * TODO: Replace these hash tables with simpler move-to-front LRU
79 * lists with a bounded size (128 items?). The hash is a bit faster,
80 * but has a bad pathology in which it thrashes a single bucket. Even
81 * walking a list of 128 items is a lot faster than calling
82 * getpwnam()!
83 */
84 int
archive_write_disk_set_standard_lookup(struct archive * a)85 archive_write_disk_set_standard_lookup(struct archive *a)
86 {
87 struct bucket *ucache = calloc(cache_size, sizeof(struct bucket));
88 struct bucket *gcache = calloc(cache_size, sizeof(struct bucket));
89 if (ucache == NULL || gcache == NULL) {
90 free(ucache);
91 free(gcache);
92 return (ARCHIVE_FATAL);
93 }
94 archive_write_disk_set_group_lookup(a, gcache, lookup_gid, cleanup);
95 archive_write_disk_set_user_lookup(a, ucache, lookup_uid, cleanup);
96 return (ARCHIVE_OK);
97 }
98
99 static int64_t
lookup_gid(void * private_data,const char * gname,int64_t gid)100 lookup_gid(void *private_data, const char *gname, int64_t gid)
101 {
102 int h;
103 struct bucket *b;
104 struct bucket *gcache = (struct bucket *)private_data;
105
106 /* If no gname, just use the gid provided. */
107 if (gname == NULL || *gname == '\0')
108 return (gid);
109
110 /* Try to find gname in the cache. */
111 h = hash(gname);
112 b = &gcache[h % cache_size ];
113 if (b->name != NULL && b->hash == h && strcmp(gname, b->name) == 0)
114 return ((gid_t)b->id);
115
116 /* Free the cache slot for a new entry. */
117 free(b->name);
118 b->name = strdup(gname);
119 /* Note: If strdup fails, that's okay; we just won't cache. */
120 b->hash = h;
121 #if HAVE_GRP_H
122 # if HAVE_GETGRNAM_R
123 {
124 char _buffer[128];
125 size_t bufsize = 128;
126 char *buffer = _buffer;
127 char *allocated = NULL;
128 struct group grent, *result;
129 int r;
130
131 for (;;) {
132 result = &grent; /* Old getgrnam_r ignores last arg. */
133 r = getgrnam_r(gname, &grent, buffer, bufsize, &result);
134 if (r == 0)
135 break;
136 if (r != ERANGE)
137 break;
138 bufsize *= 2;
139 free(allocated);
140 allocated = malloc(bufsize);
141 if (allocated == NULL)
142 break;
143 buffer = allocated;
144 }
145 if (result != NULL)
146 gid = result->gr_gid;
147 free(allocated);
148 }
149 # else /* HAVE_GETGRNAM_R */
150 {
151 struct group *result;
152
153 result = getgrnam(gname);
154 if (result != NULL)
155 gid = result->gr_gid;
156 }
157 # endif /* HAVE_GETGRNAM_R */
158 #elif defined(_WIN32) && !defined(__CYGWIN__)
159 /* TODO: do a gname->gid lookup for Windows. */
160 #else
161 #error No way to perform gid lookups on this platform
162 #endif
163 b->id = (gid_t)gid;
164
165 return (gid);
166 }
167
168 static int64_t
lookup_uid(void * private_data,const char * uname,int64_t uid)169 lookup_uid(void *private_data, const char *uname, int64_t uid)
170 {
171 int h;
172 struct bucket *b;
173 struct bucket *ucache = (struct bucket *)private_data;
174
175 /* If no uname, just use the uid provided. */
176 if (uname == NULL || *uname == '\0')
177 return (uid);
178
179 /* Try to find uname in the cache. */
180 h = hash(uname);
181 b = &ucache[h % cache_size ];
182 if (b->name != NULL && b->hash == h && strcmp(uname, b->name) == 0)
183 return ((uid_t)b->id);
184
185 /* Free the cache slot for a new entry. */
186 free(b->name);
187 b->name = strdup(uname);
188 /* Note: If strdup fails, that's okay; we just won't cache. */
189 b->hash = h;
190 #if HAVE_PWD_H
191 # if HAVE_GETPWNAM_R
192 {
193 char _buffer[128];
194 size_t bufsize = 128;
195 char *buffer = _buffer;
196 char *allocated = NULL;
197 struct passwd pwent, *result;
198 int r;
199
200 for (;;) {
201 result = &pwent; /* Old getpwnam_r ignores last arg. */
202 r = getpwnam_r(uname, &pwent, buffer, bufsize, &result);
203 if (r == 0)
204 break;
205 if (r != ERANGE)
206 break;
207 bufsize *= 2;
208 free(allocated);
209 allocated = malloc(bufsize);
210 if (allocated == NULL)
211 break;
212 buffer = allocated;
213 }
214 if (result != NULL)
215 uid = result->pw_uid;
216 free(allocated);
217 }
218 # else /* HAVE_GETPWNAM_R */
219 {
220 struct passwd *result;
221
222 result = getpwnam(uname);
223 if (result != NULL)
224 uid = result->pw_uid;
225 }
226 #endif /* HAVE_GETPWNAM_R */
227 #elif defined(_WIN32) && !defined(__CYGWIN__)
228 /* TODO: do a uname->uid lookup for Windows. */
229 #else
230 #error No way to look up uids on this platform
231 #endif
232 b->id = (uid_t)uid;
233
234 return (uid);
235 }
236
237 static void
cleanup(void * private)238 cleanup(void *private)
239 {
240 size_t i;
241 struct bucket *cache = (struct bucket *)private;
242
243 for (i = 0; i < cache_size; i++)
244 free(cache[i].name);
245 free(cache);
246 }
247
248
249 static unsigned int
hash(const char * p)250 hash(const char *p)
251 {
252 /* A 32-bit version of Peter Weinberger's (PJW) hash algorithm,
253 as used by ELF for hashing function names. */
254 unsigned g, h = 0;
255 while (*p != '\0') {
256 h = (h << 4) + *p++;
257 if ((g = h & 0xF0000000) != 0) {
258 h ^= g >> 24;
259 h &= 0x0FFFFFFF;
260 }
261 }
262 return h;
263 }
264