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