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
28 #ifdef HAVE_SYS_TYPES_H
29 #include <sys/types.h>
30 #endif
31 #ifdef HAVE_ERRNO_H
32 #include <errno.h>
33 #endif
34 #ifdef HAVE_GRP_H
35 #include <grp.h>
36 #endif
37 #ifdef HAVE_PWD_H
38 #include <pwd.h>
39 #endif
40 #ifdef HAVE_STDLIB_H
41 #include <stdlib.h>
42 #endif
43 #ifdef HAVE_STRING_H
44 #include <string.h>
45 #endif
46
47 #include "archive.h"
48 #include "archive_private.h"
49 #include "archive_read_private.h"
50 #include "archive_write_disk_private.h"
51
52 struct bucket {
53 char *name;
54 int hash;
55 id_t id;
56 };
57
58 static const size_t cache_size = 127;
59 static unsigned int hash(const char *);
60 static int64_t lookup_gid(void *, const char *uname, int64_t);
61 static int64_t lookup_uid(void *, const char *uname, int64_t);
62 static void cleanup(void *);
63
64 /*
65 * Installs functions that use getpwnam()/getgrnam()---along with
66 * a simple cache to accelerate such lookups---into the archive_write_disk
67 * object. This is in a separate file because getpwnam()/getgrnam()
68 * can pull in a LOT of library code (including NIS/LDAP functions, which
69 * pull in DNS resolvers, etc). This can easily top 500kB, which makes
70 * it inappropriate for some space-constrained applications.
71 *
72 * Applications that are size-sensitive may want to just use the
73 * real default functions (defined in archive_write_disk.c) that just
74 * use the uid/gid without the lookup. Or define your own custom functions
75 * if you prefer.
76 *
77 * TODO: Replace these hash tables with simpler move-to-front LRU
78 * lists with a bounded size (128 items?). The hash is a bit faster,
79 * but has a bad pathology in which it thrashes a single bucket. Even
80 * walking a list of 128 items is a lot faster than calling
81 * getpwnam()!
82 */
83 int
archive_write_disk_set_standard_lookup(struct archive * a)84 archive_write_disk_set_standard_lookup(struct archive *a)
85 {
86 struct bucket *ucache = calloc(cache_size, sizeof(struct bucket));
87 struct bucket *gcache = calloc(cache_size, sizeof(struct bucket));
88 if (ucache == NULL || gcache == NULL) {
89 free(ucache);
90 free(gcache);
91 return (ARCHIVE_FATAL);
92 }
93 archive_write_disk_set_group_lookup(a, gcache, lookup_gid, cleanup);
94 archive_write_disk_set_user_lookup(a, ucache, lookup_uid, cleanup);
95 return (ARCHIVE_OK);
96 }
97
98 static int64_t
lookup_gid(void * private_data,const char * gname,int64_t gid)99 lookup_gid(void *private_data, const char *gname, int64_t gid)
100 {
101 int h;
102 struct bucket *b;
103 struct bucket *gcache = (struct bucket *)private_data;
104
105 /* If no gname, just use the gid provided. */
106 if (gname == NULL || *gname == '\0')
107 return (gid);
108
109 /* Try to find gname in the cache. */
110 h = hash(gname);
111 b = &gcache[h % cache_size ];
112 if (b->name != NULL && b->hash == h && strcmp(gname, b->name) == 0)
113 return ((gid_t)b->id);
114
115 /* Free the cache slot for a new entry. */
116 free(b->name);
117 b->name = strdup(gname);
118 /* Note: If strdup fails, that's okay; we just won't cache. */
119 b->hash = h;
120 #if HAVE_GRP_H
121 # if HAVE_GETGRNAM_R
122 {
123 char _buffer[128];
124 size_t bufsize = 128;
125 char *buffer = _buffer;
126 char *allocated = NULL;
127 struct group grent, *result;
128 int r;
129
130 for (;;) {
131 result = &grent; /* Old getgrnam_r ignores last arg. */
132 r = getgrnam_r(gname, &grent, buffer, bufsize, &result);
133 if (r == 0)
134 break;
135 if (r != ERANGE)
136 break;
137 bufsize *= 2;
138 free(allocated);
139 allocated = malloc(bufsize);
140 if (allocated == NULL)
141 break;
142 buffer = allocated;
143 }
144 if (result != NULL)
145 gid = result->gr_gid;
146 free(allocated);
147 }
148 # else /* HAVE_GETGRNAM_R */
149 {
150 struct group *result;
151
152 result = getgrnam(gname);
153 if (result != NULL)
154 gid = result->gr_gid;
155 }
156 # endif /* HAVE_GETGRNAM_R */
157 #elif defined(_WIN32) && !defined(__CYGWIN__)
158 /* TODO: do a gname->gid lookup for Windows. */
159 #else
160 #error No way to perform gid lookups on this platform
161 #endif
162 b->id = (gid_t)gid;
163
164 return (gid);
165 }
166
167 static int64_t
lookup_uid(void * private_data,const char * uname,int64_t uid)168 lookup_uid(void *private_data, const char *uname, int64_t uid)
169 {
170 int h;
171 struct bucket *b;
172 struct bucket *ucache = (struct bucket *)private_data;
173
174 /* If no uname, just use the uid provided. */
175 if (uname == NULL || *uname == '\0')
176 return (uid);
177
178 /* Try to find uname in the cache. */
179 h = hash(uname);
180 b = &ucache[h % cache_size ];
181 if (b->name != NULL && b->hash == h && strcmp(uname, b->name) == 0)
182 return ((uid_t)b->id);
183
184 /* Free the cache slot for a new entry. */
185 free(b->name);
186 b->name = strdup(uname);
187 /* Note: If strdup fails, that's okay; we just won't cache. */
188 b->hash = h;
189 #if HAVE_PWD_H
190 # if HAVE_GETPWNAM_R
191 {
192 char _buffer[128];
193 size_t bufsize = 128;
194 char *buffer = _buffer;
195 char *allocated = NULL;
196 struct passwd pwent, *result;
197 int r;
198
199 for (;;) {
200 result = &pwent; /* Old getpwnam_r ignores last arg. */
201 r = getpwnam_r(uname, &pwent, buffer, bufsize, &result);
202 if (r == 0)
203 break;
204 if (r != ERANGE)
205 break;
206 bufsize *= 2;
207 free(allocated);
208 allocated = malloc(bufsize);
209 if (allocated == NULL)
210 break;
211 buffer = allocated;
212 }
213 if (result != NULL)
214 uid = result->pw_uid;
215 free(allocated);
216 }
217 # else /* HAVE_GETPWNAM_R */
218 {
219 struct passwd *result;
220
221 result = getpwnam(uname);
222 if (result != NULL)
223 uid = result->pw_uid;
224 }
225 #endif /* HAVE_GETPWNAM_R */
226 #elif defined(_WIN32) && !defined(__CYGWIN__)
227 /* TODO: do a uname->uid lookup for Windows. */
228 #else
229 #error No way to look up uids on this platform
230 #endif
231 b->id = (uid_t)uid;
232
233 return (uid);
234 }
235
236 static void
cleanup(void * private)237 cleanup(void *private)
238 {
239 size_t i;
240 struct bucket *cache = (struct bucket *)private;
241
242 for (i = 0; i < cache_size; i++)
243 free(cache[i].name);
244 free(cache);
245 }
246
247
248 static unsigned int
hash(const char * p)249 hash(const char *p)
250 {
251 /* A 32-bit version of Peter Weinberger's (PJW) hash algorithm,
252 as used by ELF for hashing function names. */
253 unsigned g, h = 0;
254 while (*p != '\0') {
255 h = (h << 4) + *p++;
256 if ((g = h & 0xF0000000) != 0) {
257 h ^= g >> 24;
258 h &= 0x0FFFFFFF;
259 }
260 }
261 return h;
262 }
263