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_entry_link_resolver.c 201100 2009-12-28 03:05:31Z kientzle $");
28
29 #ifdef HAVE_SYS_STAT_H
30 #include <sys/stat.h>
31 #endif
32 #ifdef HAVE_ERRNO_H
33 #include <errno.h>
34 #endif
35 #include <stdio.h>
36 #ifdef HAVE_STDLIB_H
37 #include <stdlib.h>
38 #endif
39 #ifdef HAVE_STRING_H
40 #include <string.h>
41 #endif
42
43 #include "archive.h"
44 #include "archive_entry.h"
45
46 /*
47 * This is mostly a pretty straightforward hash table implementation.
48 * The only interesting bit is the different strategies used to
49 * match up links. These strategies match those used by various
50 * archiving formats:
51 * tar - content stored with first link, remainder refer back to it.
52 * This requires us to match each subsequent link up with the
53 * first appearance.
54 * cpio - Old cpio just stored body with each link, match-ups were
55 * implicit. This is trivial.
56 * new cpio - New cpio only stores body with last link, match-ups
57 * are implicit. This is actually quite tricky; see the notes
58 * below.
59 */
60
61 /* Users pass us a format code, we translate that into a strategy here. */
62 #define ARCHIVE_ENTRY_LINKIFY_LIKE_TAR 0
63 #define ARCHIVE_ENTRY_LINKIFY_LIKE_MTREE 1
64 #define ARCHIVE_ENTRY_LINKIFY_LIKE_OLD_CPIO 2
65 #define ARCHIVE_ENTRY_LINKIFY_LIKE_NEW_CPIO 3
66
67 /* Initial size of link cache. */
68 #define links_cache_initial_size 1024
69
70 struct links_entry {
71 struct links_entry *next;
72 struct links_entry *previous;
73 struct archive_entry *canonical;
74 struct archive_entry *entry;
75 size_t hash;
76 unsigned int links; /* # links not yet seen */
77 };
78
79 struct archive_entry_linkresolver {
80 struct links_entry **buckets;
81 struct links_entry *spare;
82 unsigned long number_entries;
83 size_t number_buckets;
84 int strategy;
85 };
86
87 #define NEXT_ENTRY_DEFERRED 1
88 #define NEXT_ENTRY_PARTIAL 2
89 #define NEXT_ENTRY_ALL (NEXT_ENTRY_DEFERRED | NEXT_ENTRY_PARTIAL)
90
91 static struct links_entry *find_entry(struct archive_entry_linkresolver *,
92 struct archive_entry *);
93 static void grow_hash(struct archive_entry_linkresolver *);
94 static struct links_entry *insert_entry(struct archive_entry_linkresolver *,
95 struct archive_entry *);
96 static struct links_entry *next_entry(struct archive_entry_linkresolver *,
97 int);
98
99 struct archive_entry_linkresolver *
archive_entry_linkresolver_new(void)100 archive_entry_linkresolver_new(void)
101 {
102 struct archive_entry_linkresolver *res;
103
104 /* Check for positive power-of-two */
105 if (links_cache_initial_size == 0 ||
106 (links_cache_initial_size & (links_cache_initial_size - 1)) != 0)
107 return (NULL);
108
109 res = calloc(1, sizeof(struct archive_entry_linkresolver));
110 if (res == NULL)
111 return (NULL);
112 res->number_buckets = links_cache_initial_size;
113 res->buckets = calloc(res->number_buckets, sizeof(res->buckets[0]));
114 if (res->buckets == NULL) {
115 free(res);
116 return (NULL);
117 }
118 return (res);
119 }
120
121 void
archive_entry_linkresolver_set_strategy(struct archive_entry_linkresolver * res,int fmt)122 archive_entry_linkresolver_set_strategy(struct archive_entry_linkresolver *res,
123 int fmt)
124 {
125 int fmtbase = fmt & ARCHIVE_FORMAT_BASE_MASK;
126
127 switch (fmtbase) {
128 case ARCHIVE_FORMAT_7ZIP:
129 case ARCHIVE_FORMAT_AR:
130 case ARCHIVE_FORMAT_ZIP:
131 res->strategy = ARCHIVE_ENTRY_LINKIFY_LIKE_OLD_CPIO;
132 break;
133 case ARCHIVE_FORMAT_CPIO:
134 switch (fmt) {
135 case ARCHIVE_FORMAT_CPIO_SVR4_NOCRC:
136 case ARCHIVE_FORMAT_CPIO_SVR4_CRC:
137 res->strategy = ARCHIVE_ENTRY_LINKIFY_LIKE_NEW_CPIO;
138 break;
139 default:
140 res->strategy = ARCHIVE_ENTRY_LINKIFY_LIKE_OLD_CPIO;
141 break;
142 }
143 break;
144 case ARCHIVE_FORMAT_MTREE:
145 res->strategy = ARCHIVE_ENTRY_LINKIFY_LIKE_MTREE;
146 break;
147 case ARCHIVE_FORMAT_ISO9660:
148 case ARCHIVE_FORMAT_SHAR:
149 case ARCHIVE_FORMAT_TAR:
150 case ARCHIVE_FORMAT_XAR:
151 res->strategy = ARCHIVE_ENTRY_LINKIFY_LIKE_TAR;
152 break;
153 default:
154 res->strategy = ARCHIVE_ENTRY_LINKIFY_LIKE_OLD_CPIO;
155 break;
156 }
157 }
158
159 void
archive_entry_linkresolver_free(struct archive_entry_linkresolver * res)160 archive_entry_linkresolver_free(struct archive_entry_linkresolver *res)
161 {
162 struct links_entry *le;
163
164 if (res == NULL)
165 return;
166
167 while ((le = next_entry(res, NEXT_ENTRY_ALL)) != NULL)
168 archive_entry_free(le->entry);
169 free(res->buckets);
170 free(res);
171 }
172
173 void
archive_entry_linkify(struct archive_entry_linkresolver * res,struct archive_entry ** e,struct archive_entry ** f)174 archive_entry_linkify(struct archive_entry_linkresolver *res,
175 struct archive_entry **e, struct archive_entry **f)
176 {
177 struct links_entry *le;
178 struct archive_entry *t;
179
180 *f = NULL; /* Default: Don't return a second entry. */
181
182 if (*e == NULL) {
183 le = next_entry(res, NEXT_ENTRY_DEFERRED);
184 if (le != NULL) {
185 *e = le->entry;
186 le->entry = NULL;
187 }
188 return;
189 }
190
191 /* If it has only one link, then we're done. */
192 if (archive_entry_nlink(*e) == 1)
193 return;
194 /* Directories, devices never have hardlinks. */
195 if (archive_entry_filetype(*e) == AE_IFDIR
196 || archive_entry_filetype(*e) == AE_IFBLK
197 || archive_entry_filetype(*e) == AE_IFCHR)
198 return;
199
200 switch (res->strategy) {
201 case ARCHIVE_ENTRY_LINKIFY_LIKE_TAR:
202 le = find_entry(res, *e);
203 if (le != NULL) {
204 archive_entry_unset_size(*e);
205 archive_entry_copy_hardlink(*e,
206 archive_entry_pathname(le->canonical));
207 } else
208 insert_entry(res, *e);
209 return;
210 case ARCHIVE_ENTRY_LINKIFY_LIKE_MTREE:
211 le = find_entry(res, *e);
212 if (le != NULL) {
213 archive_entry_copy_hardlink(*e,
214 archive_entry_pathname(le->canonical));
215 } else
216 insert_entry(res, *e);
217 return;
218 case ARCHIVE_ENTRY_LINKIFY_LIKE_OLD_CPIO:
219 /* This one is trivial. */
220 return;
221 case ARCHIVE_ENTRY_LINKIFY_LIKE_NEW_CPIO:
222 le = find_entry(res, *e);
223 if (le != NULL) {
224 /*
225 * Put the new entry in le, return the
226 * old entry from le.
227 */
228 t = *e;
229 *e = le->entry;
230 le->entry = t;
231 /* Make the old entry into a hardlink. */
232 archive_entry_unset_size(*e);
233 archive_entry_copy_hardlink(*e,
234 archive_entry_pathname(le->canonical));
235 /* If we ran out of links, return the
236 * final entry as well. */
237 if (le->links == 0) {
238 *f = le->entry;
239 le->entry = NULL;
240 }
241 } else {
242 /*
243 * If we haven't seen it, tuck it away
244 * for future use.
245 */
246 le = insert_entry(res, *e);
247 if (le == NULL)
248 /* XXX We should return an error code XXX */
249 return;
250 le->entry = *e;
251 *e = NULL;
252 }
253 return;
254 default:
255 break;
256 }
257 return;
258 }
259
260 static struct links_entry *
find_entry(struct archive_entry_linkresolver * res,struct archive_entry * entry)261 find_entry(struct archive_entry_linkresolver *res,
262 struct archive_entry *entry)
263 {
264 struct links_entry *le;
265 size_t hash, bucket;
266 dev_t dev;
267 int64_t ino;
268
269 /* Free a held entry. */
270 if (res->spare != NULL) {
271 archive_entry_free(res->spare->canonical);
272 archive_entry_free(res->spare->entry);
273 free(res->spare);
274 res->spare = NULL;
275 }
276
277 dev = archive_entry_dev(entry);
278 ino = archive_entry_ino64(entry);
279 hash = (size_t)(dev ^ ino);
280
281 /* Try to locate this entry in the links cache. */
282 bucket = hash & (res->number_buckets - 1);
283 for (le = res->buckets[bucket]; le != NULL; le = le->next) {
284 if (le->hash == hash
285 && dev == archive_entry_dev(le->canonical)
286 && ino == archive_entry_ino64(le->canonical)) {
287 /*
288 * Decrement link count each time and release
289 * the entry if it hits zero. This saves
290 * memory and is necessary for detecting
291 * missed links.
292 */
293 --le->links;
294 if (le->links > 0)
295 return (le);
296 /* Remove it from this hash bucket. */
297 if (le->previous != NULL)
298 le->previous->next = le->next;
299 if (le->next != NULL)
300 le->next->previous = le->previous;
301 if (res->buckets[bucket] == le)
302 res->buckets[bucket] = le->next;
303 res->number_entries--;
304 /* Defer freeing this entry. */
305 res->spare = le;
306 return (le);
307 }
308 }
309 return (NULL);
310 }
311
312 static struct links_entry *
next_entry(struct archive_entry_linkresolver * res,int mode)313 next_entry(struct archive_entry_linkresolver *res, int mode)
314 {
315 struct links_entry *le;
316 size_t bucket;
317
318 /* Free a held entry. */
319 if (res->spare != NULL) {
320 archive_entry_free(res->spare->canonical);
321 archive_entry_free(res->spare->entry);
322 free(res->spare);
323 res->spare = NULL;
324 }
325
326 /* Look for next non-empty bucket in the links cache. */
327 for (bucket = 0; bucket < res->number_buckets; bucket++) {
328 for (le = res->buckets[bucket]; le != NULL; le = le->next) {
329 if (le->entry != NULL &&
330 (mode & NEXT_ENTRY_DEFERRED) == 0)
331 continue;
332 if (le->entry == NULL &&
333 (mode & NEXT_ENTRY_PARTIAL) == 0)
334 continue;
335 /* Remove it from this hash bucket. */
336 if (le->next != NULL)
337 le->next->previous = le->previous;
338 if (le->previous != NULL)
339 le->previous->next = le->next;
340 else
341 res->buckets[bucket] = le->next;
342 res->number_entries--;
343 /* Defer freeing this entry. */
344 res->spare = le;
345 return (le);
346 }
347 }
348 return (NULL);
349 }
350
351 static struct links_entry *
insert_entry(struct archive_entry_linkresolver * res,struct archive_entry * entry)352 insert_entry(struct archive_entry_linkresolver *res,
353 struct archive_entry *entry)
354 {
355 struct links_entry *le;
356 size_t hash, bucket;
357
358 /* Add this entry to the links cache. */
359 le = calloc(1, sizeof(struct links_entry));
360 if (le == NULL)
361 return (NULL);
362 le->canonical = archive_entry_clone(entry);
363
364 /* If the links cache is getting too full, enlarge the hash table. */
365 if (res->number_entries > res->number_buckets * 2)
366 grow_hash(res);
367
368 hash = (size_t)(archive_entry_dev(entry) ^ archive_entry_ino64(entry));
369 bucket = hash & (res->number_buckets - 1);
370
371 /* If we could allocate the entry, record it. */
372 if (res->buckets[bucket] != NULL)
373 res->buckets[bucket]->previous = le;
374 res->number_entries++;
375 le->next = res->buckets[bucket];
376 le->previous = NULL;
377 res->buckets[bucket] = le;
378 le->hash = hash;
379 le->links = archive_entry_nlink(entry) - 1;
380 return (le);
381 }
382
383 static void
grow_hash(struct archive_entry_linkresolver * res)384 grow_hash(struct archive_entry_linkresolver *res)
385 {
386 struct links_entry *le, **new_buckets;
387 size_t new_size;
388 size_t i, bucket;
389
390 /* Try to enlarge the bucket list. */
391 new_size = res->number_buckets * 2;
392 if (new_size < res->number_buckets)
393 return;
394 new_buckets = calloc(new_size, sizeof(struct links_entry *));
395
396 if (new_buckets == NULL)
397 return;
398
399 for (i = 0; i < res->number_buckets; i++) {
400 while (res->buckets[i] != NULL) {
401 /* Remove entry from old bucket. */
402 le = res->buckets[i];
403 res->buckets[i] = le->next;
404
405 /* Add entry to new bucket. */
406 bucket = le->hash & (new_size - 1);
407
408 if (new_buckets[bucket] != NULL)
409 new_buckets[bucket]->previous = le;
410 le->next = new_buckets[bucket];
411 le->previous = NULL;
412 new_buckets[bucket] = le;
413 }
414 }
415 free(res->buckets);
416 res->buckets = new_buckets;
417 res->number_buckets = new_size;
418 }
419
420 struct archive_entry *
archive_entry_partial_links(struct archive_entry_linkresolver * res,unsigned int * links)421 archive_entry_partial_links(struct archive_entry_linkresolver *res,
422 unsigned int *links)
423 {
424 struct archive_entry *e;
425 struct links_entry *le;
426
427 /* Free a held entry. */
428 if (res->spare != NULL) {
429 archive_entry_free(res->spare->canonical);
430 archive_entry_free(res->spare->entry);
431 free(res->spare);
432 res->spare = NULL;
433 }
434
435 le = next_entry(res, NEXT_ENTRY_PARTIAL);
436 if (le != NULL) {
437 e = le->canonical;
438 if (links != NULL)
439 *links = le->links;
440 le->canonical = NULL;
441 } else {
442 e = NULL;
443 if (links != NULL)
444 *links = 0;
445 }
446 return (e);
447 }
448