archive_write_disk_set_standard_lookup.c revision 302408 
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: stable/11/contrib/libarchive/libarchive/archive_write_disk_set_standard_lookup.c 299529 2016-05-12 10:16:16Z mm $");
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
53struct bucket {
54	char	*name;
55	int	 hash;
56	id_t	 id;
57};
58
59static const size_t cache_size = 127;
60static unsigned int	hash(const char *);
61static int64_t	lookup_gid(void *, const char *uname, int64_t);
62static int64_t	lookup_uid(void *, const char *uname, int64_t);
63static 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 */
84int
85archive_write_disk_set_standard_lookup(struct archive *a)
86{
87	struct bucket *ucache = malloc(cache_size * sizeof(struct bucket));
88	struct bucket *gcache = malloc(cache_size * sizeof(struct bucket));
89	if (ucache == NULL || gcache == NULL) {
90		free(ucache);
91		free(gcache);
92		return (ARCHIVE_FATAL);
93	}
94	memset(ucache, 0, cache_size * sizeof(struct bucket));
95	memset(gcache, 0, cache_size * sizeof(struct bucket));
96	archive_write_disk_set_group_lookup(a, gcache, lookup_gid, cleanup);
97	archive_write_disk_set_user_lookup(a, ucache, lookup_uid, cleanup);
98	return (ARCHIVE_OK);
99}
100
101static int64_t
102lookup_gid(void *private_data, const char *gname, int64_t gid)
103{
104	int h;
105	struct bucket *b;
106	struct bucket *gcache = (struct bucket *)private_data;
107
108	/* If no gname, just use the gid provided. */
109	if (gname == NULL || *gname == '\0')
110		return (gid);
111
112	/* Try to find gname in the cache. */
113	h = hash(gname);
114	b = &gcache[h % cache_size ];
115	if (b->name != NULL && b->hash == h && strcmp(gname, b->name) == 0)
116		return ((gid_t)b->id);
117
118	/* Free the cache slot for a new entry. */
119	if (b->name != NULL)
120		free(b->name);
121	b->name = strdup(gname);
122	/* Note: If strdup fails, that's okay; we just won't cache. */
123	b->hash = h;
124#if HAVE_GRP_H
125#  if HAVE_GETGRNAM_R
126	{
127		char _buffer[128];
128		size_t bufsize = 128;
129		char *buffer = _buffer;
130		char *allocated = NULL;
131		struct group	grent, *result;
132		int r;
133
134		for (;;) {
135			result = &grent; /* Old getgrnam_r ignores last arg. */
136			r = getgrnam_r(gname, &grent, buffer, bufsize, &result);
137			if (r == 0)
138				break;
139			if (r != ERANGE)
140				break;
141			bufsize *= 2;
142			free(allocated);
143			allocated = malloc(bufsize);
144			if (allocated == NULL)
145				break;
146			buffer = allocated;
147		}
148		if (result != NULL)
149			gid = result->gr_gid;
150		free(allocated);
151	}
152#  else /* HAVE_GETGRNAM_R */
153	{
154		struct group *result;
155
156		result = getgrnam(gname);
157		if (result != NULL)
158			gid = result->gr_gid;
159	}
160#  endif /* HAVE_GETGRNAM_R */
161#elif defined(_WIN32) && !defined(__CYGWIN__)
162	/* TODO: do a gname->gid lookup for Windows. */
163#else
164	#error No way to perform gid lookups on this platform
165#endif
166	b->id = (gid_t)gid;
167
168	return (gid);
169}
170
171static int64_t
172lookup_uid(void *private_data, const char *uname, int64_t uid)
173{
174	int h;
175	struct bucket *b;
176	struct bucket *ucache = (struct bucket *)private_data;
177
178	/* If no uname, just use the uid provided. */
179	if (uname == NULL || *uname == '\0')
180		return (uid);
181
182	/* Try to find uname in the cache. */
183	h = hash(uname);
184	b = &ucache[h % cache_size ];
185	if (b->name != NULL && b->hash == h && strcmp(uname, b->name) == 0)
186		return ((uid_t)b->id);
187
188	/* Free the cache slot for a new entry. */
189	if (b->name != NULL)
190		free(b->name);
191	b->name = strdup(uname);
192	/* Note: If strdup fails, that's okay; we just won't cache. */
193	b->hash = h;
194#if HAVE_PWD_H
195#  if HAVE_GETPWNAM_R
196	{
197		char _buffer[128];
198		size_t bufsize = 128;
199		char *buffer = _buffer;
200		char *allocated = NULL;
201		struct passwd	pwent, *result;
202		int r;
203
204		for (;;) {
205			result = &pwent; /* Old getpwnam_r ignores last arg. */
206			r = getpwnam_r(uname, &pwent, buffer, bufsize, &result);
207			if (r == 0)
208				break;
209			if (r != ERANGE)
210				break;
211			bufsize *= 2;
212			free(allocated);
213			allocated = malloc(bufsize);
214			if (allocated == NULL)
215				break;
216			buffer = allocated;
217		}
218		if (result != NULL)
219			uid = result->pw_uid;
220		free(allocated);
221	}
222#  else /* HAVE_GETPWNAM_R */
223	{
224		struct passwd *result;
225
226		result = getpwnam(uname);
227		if (result != NULL)
228			uid = result->pw_uid;
229	}
230#endif	/* HAVE_GETPWNAM_R */
231#elif defined(_WIN32) && !defined(__CYGWIN__)
232	/* TODO: do a uname->uid lookup for Windows. */
233#else
234	#error No way to look up uids on this platform
235#endif
236	b->id = (uid_t)uid;
237
238	return (uid);
239}
240
241static void
242cleanup(void *private)
243{
244	size_t i;
245	struct bucket *cache = (struct bucket *)private;
246
247	for (i = 0; i < cache_size; i++)
248		free(cache[i].name);
249	free(cache);
250}
251
252
253static unsigned int
254hash(const char *p)
255{
256	/* A 32-bit version of Peter Weinberger's (PJW) hash algorithm,
257	   as used by ELF for hashing function names. */
258	unsigned g, h = 0;
259	while (*p != '\0') {
260		h = (h << 4) + *p++;
261		if ((g = h & 0xF0000000) != 0) {
262			h ^= g >> 24;
263			h &= 0x0FFFFFFF;
264		}
265	}
266	return h;
267}
268