1 /*- 2 * Copyright (c) 2003-2008 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 * $FreeBSD: src/lib/libarchive/archive_entry.h,v 1.31 2008/12/06 06:18:46 kientzle Exp $ 26 */ 27 28 #ifndef ARCHIVE_ENTRY_H_INCLUDED 29 #define ARCHIVE_ENTRY_H_INCLUDED 30 31 /* 32 * Note: archive_entry.h is for use outside of libarchive; the 33 * configuration headers (config.h, archive_platform.h, etc.) are 34 * purely internal. Do NOT use HAVE_XXX configuration macros to 35 * control the behavior of this header! If you must conditionalize, 36 * use predefined compiler and/or platform macros. 37 */ 38 39 #include <sys/types.h> 40 #include <stddef.h> /* for wchar_t */ 41 #include <time.h> 42 43 /* Get appropriate definitions of standard POSIX-style types. */ 44 /* These should match the types used in 'struct stat' */ 45 #if defined(_WIN32) && !defined(__CYGWIN__) 46 #define __LA_INT64_T __int64 47 #define __LA_UID_T unsigned int 48 #define __LA_GID_T unsigned int 49 #define __LA_DEV_T unsigned int 50 #define __LA_MODE_T unsigned short 51 #else 52 #include <unistd.h> 53 #define __LA_INT64_T int64_t 54 #define __LA_UID_T uid_t 55 #define __LA_GID_T gid_t 56 #define __LA_DEV_T dev_t 57 #define __LA_MODE_T mode_t 58 #endif 59 60 /* 61 * XXX Is this defined for all Windows compilers? If so, in what 62 * header? It would be nice to remove the __LA_INO_T indirection and 63 * just use plain ino_t everywhere. Likewise for the other types just 64 * above. 65 */ 66 #define __LA_INO_T ino_t 67 68 69 /* 70 * On Windows, define LIBARCHIVE_STATIC if you're building or using a 71 * .lib. The default here assumes you're building a DLL. Only 72 * libarchive source should ever define __LIBARCHIVE_BUILD. 73 */ 74 #if ((defined __WIN32__) || (defined _WIN32) || defined(__CYGWIN__)) && (!defined LIBARCHIVE_STATIC) 75 # ifdef __LIBARCHIVE_BUILD 76 # ifdef __GNUC__ 77 # define __LA_DECL __attribute__((dllexport)) extern 78 # else 79 # define __LA_DECL __declspec(dllexport) 80 # endif 81 # else 82 # ifdef __GNUC__ 83 # define __LA_DECL __attribute__((dllimport)) extern 84 # else 85 # define __LA_DECL __declspec(dllimport) 86 # endif 87 # endif 88 #else 89 /* Static libraries on all platforms and shared libraries on non-Windows. */ 90 # define __LA_DECL 91 #endif 92 93 #ifdef __cplusplus 94 extern "C" { 95 #endif 96 97 /* 98 * Description of an archive entry. 99 * 100 * You can think of this as "struct stat" with some text fields added in. 101 * 102 * TODO: Add "comment", "charset", and possibly other entries that are 103 * supported by "pax interchange" format. However, GNU, ustar, cpio, 104 * and other variants don't support these features, so they're not an 105 * excruciatingly high priority right now. 106 * 107 * TODO: "pax interchange" format allows essentially arbitrary 108 * key/value attributes to be attached to any entry. Supporting 109 * such extensions may make this library useful for special 110 * applications (e.g., a package manager could attach special 111 * package-management attributes to each entry). 112 */ 113 struct archive_entry; 114 115 /* 116 * File-type constants. These are returned from archive_entry_filetype() 117 * and passed to archive_entry_set_filetype(). 118 * 119 * These values match S_XXX defines on every platform I've checked, 120 * including Windows, AIX, Linux, Solaris, and BSD. They're 121 * (re)defined here because platforms generally don't define the ones 122 * they don't support. For example, Windows doesn't define S_IFLNK or 123 * S_IFBLK. Instead of having a mass of conditional logic and system 124 * checks to define any S_XXX values that aren't supported locally, 125 * I've just defined a new set of such constants so that 126 * libarchive-based applications can manipulate and identify archive 127 * entries properly even if the hosting platform can't store them on 128 * disk. 129 * 130 * These values are also used directly within some portable formats, 131 * such as cpio. If you find a platform that varies from these, the 132 * correct solution is to leave these alone and translate from these 133 * portable values to platform-native values when entries are read from 134 * or written to disk. 135 */ 136 #define AE_IFMT 0170000 137 #define AE_IFREG 0100000 138 #define AE_IFLNK 0120000 139 #define AE_IFSOCK 0140000 140 #define AE_IFCHR 0020000 141 #define AE_IFBLK 0060000 142 #define AE_IFDIR 0040000 143 #define AE_IFIFO 0010000 144 145 /* 146 * Basic object manipulation 147 */ 148 149 __LA_DECL struct archive_entry *archive_entry_clear(struct archive_entry *); 150 /* The 'clone' function does a deep copy; all of the strings are copied too. */ 151 __LA_DECL struct archive_entry *archive_entry_clone(struct archive_entry *); 152 __LA_DECL void archive_entry_free(struct archive_entry *); 153 __LA_DECL struct archive_entry *archive_entry_new(void); 154 155 /* 156 * Retrieve fields from an archive_entry. 157 * 158 * There are a number of implicit conversions among these fields. For 159 * example, if a regular string field is set and you read the _w wide 160 * character field, the entry will implicitly convert narrow-to-wide 161 * using the current locale. Similarly, dev values are automatically 162 * updated when you write devmajor or devminor and vice versa. 163 * 164 * In addition, fields can be "set" or "unset." Unset string fields 165 * return NULL, non-string fields have _is_set() functions to test 166 * whether they've been set. You can "unset" a string field by 167 * assigning NULL; non-string fields have _unset() functions to 168 * unset them. 169 * 170 * Note: There is one ambiguity in the above; string fields will 171 * also return NULL when implicit character set conversions fail. 172 * This is usually what you want. 173 */ 174 __LA_DECL time_t archive_entry_atime(struct archive_entry *); 175 __LA_DECL long archive_entry_atime_nsec(struct archive_entry *); 176 __LA_DECL int archive_entry_atime_is_set(struct archive_entry *); 177 __LA_DECL time_t archive_entry_birthtime(struct archive_entry *); 178 __LA_DECL long archive_entry_birthtime_nsec(struct archive_entry *); 179 __LA_DECL int archive_entry_birthtime_is_set(struct archive_entry *); 180 __LA_DECL time_t archive_entry_ctime(struct archive_entry *); 181 __LA_DECL long archive_entry_ctime_nsec(struct archive_entry *); 182 __LA_DECL int archive_entry_ctime_is_set(struct archive_entry *); 183 __LA_DECL dev_t archive_entry_dev(struct archive_entry *); 184 __LA_DECL dev_t archive_entry_devmajor(struct archive_entry *); 185 __LA_DECL dev_t archive_entry_devminor(struct archive_entry *); 186 __LA_DECL __LA_MODE_T archive_entry_filetype(struct archive_entry *); 187 __LA_DECL void archive_entry_fflags(struct archive_entry *, 188 unsigned long * /* set */, 189 unsigned long * /* clear */); 190 __LA_DECL const char *archive_entry_fflags_text(struct archive_entry *); 191 __LA_DECL __LA_GID_T archive_entry_gid(struct archive_entry *); 192 __LA_DECL const char *archive_entry_gname(struct archive_entry *); 193 __LA_DECL const wchar_t *archive_entry_gname_w(struct archive_entry *); 194 __LA_DECL const char *archive_entry_hardlink(struct archive_entry *); 195 __LA_DECL const wchar_t *archive_entry_hardlink_w(struct archive_entry *); 196 __LA_DECL __LA_INO_T archive_entry_ino(struct archive_entry *); 197 __LA_DECL __LA_MODE_T archive_entry_mode(struct archive_entry *); 198 __LA_DECL time_t archive_entry_mtime(struct archive_entry *); 199 __LA_DECL long archive_entry_mtime_nsec(struct archive_entry *); 200 __LA_DECL int archive_entry_mtime_is_set(struct archive_entry *); 201 __LA_DECL unsigned int archive_entry_nlink(struct archive_entry *); 202 __LA_DECL const char *archive_entry_pathname(struct archive_entry *); 203 __LA_DECL const wchar_t *archive_entry_pathname_w(struct archive_entry *); 204 __LA_DECL dev_t archive_entry_rdev(struct archive_entry *); 205 __LA_DECL dev_t archive_entry_rdevmajor(struct archive_entry *); 206 __LA_DECL dev_t archive_entry_rdevminor(struct archive_entry *); 207 __LA_DECL const char *archive_entry_sourcepath(struct archive_entry *); 208 __LA_DECL __LA_INT64_T archive_entry_size(struct archive_entry *); 209 __LA_DECL int archive_entry_size_is_set(struct archive_entry *); 210 __LA_DECL const char *archive_entry_strmode(struct archive_entry *); 211 __LA_DECL const char *archive_entry_symlink(struct archive_entry *); 212 __LA_DECL const wchar_t *archive_entry_symlink_w(struct archive_entry *); 213 __LA_DECL __LA_UID_T archive_entry_uid(struct archive_entry *); 214 __LA_DECL const char *archive_entry_uname(struct archive_entry *); 215 __LA_DECL const wchar_t *archive_entry_uname_w(struct archive_entry *); 216 217 /* 218 * Set fields in an archive_entry. 219 * 220 * Note that string 'set' functions do not copy the string, only the pointer. 221 * In contrast, 'copy' functions do copy the object pointed to. 222 * 223 * Note: As of libarchive 2.4, 'set' functions do copy the string and 224 * are therefore exact synonyms for the 'copy' versions. The 'copy' 225 * names will be retired in libarchive 3.0. 226 */ 227 228 __LA_DECL void archive_entry_set_atime(struct archive_entry *, time_t, long); 229 __LA_DECL void archive_entry_unset_atime(struct archive_entry *); 230 __LA_DECL void archive_entry_set_birthtime(struct archive_entry *, time_t, long); 231 __LA_DECL void archive_entry_unset_birthtime(struct archive_entry *); 232 __LA_DECL void archive_entry_set_ctime(struct archive_entry *, time_t, long); 233 __LA_DECL void archive_entry_unset_ctime(struct archive_entry *); 234 __LA_DECL void archive_entry_set_dev(struct archive_entry *, dev_t); 235 __LA_DECL void archive_entry_set_devmajor(struct archive_entry *, dev_t); 236 __LA_DECL void archive_entry_set_devminor(struct archive_entry *, dev_t); 237 __LA_DECL void archive_entry_set_filetype(struct archive_entry *, unsigned int); 238 __LA_DECL void archive_entry_set_fflags(struct archive_entry *, 239 unsigned long /* set */, unsigned long /* clear */); 240 /* Returns pointer to start of first invalid token, or NULL if none. */ 241 /* Note that all recognized tokens are processed, regardless. */ 242 __LA_DECL const char *archive_entry_copy_fflags_text(struct archive_entry *, 243 const char *); 244 __LA_DECL const wchar_t *archive_entry_copy_fflags_text_w(struct archive_entry *, 245 const wchar_t *); 246 __LA_DECL void archive_entry_set_gid(struct archive_entry *, __LA_GID_T); 247 __LA_DECL void archive_entry_set_gname(struct archive_entry *, const char *); 248 __LA_DECL void archive_entry_copy_gname(struct archive_entry *, const char *); 249 __LA_DECL void archive_entry_copy_gname_w(struct archive_entry *, const wchar_t *); 250 __LA_DECL int archive_entry_update_gname_utf8(struct archive_entry *, const char *); 251 __LA_DECL void archive_entry_set_hardlink(struct archive_entry *, const char *); 252 __LA_DECL void archive_entry_copy_hardlink(struct archive_entry *, const char *); 253 __LA_DECL void archive_entry_copy_hardlink_w(struct archive_entry *, const wchar_t *); 254 __LA_DECL void archive_entry_set_ino(struct archive_entry *, unsigned long); 255 __LA_DECL void archive_entry_set_link(struct archive_entry *, const char *); 256 __LA_DECL void archive_entry_copy_link(struct archive_entry *, const char *); 257 __LA_DECL void archive_entry_copy_link_w(struct archive_entry *, const wchar_t *); 258 __LA_DECL int archive_entry_update_link_utf8(struct archive_entry *, const char *); 259 __LA_DECL void archive_entry_set_mode(struct archive_entry *, __LA_MODE_T); 260 __LA_DECL void archive_entry_set_mtime(struct archive_entry *, time_t, long); 261 __LA_DECL void archive_entry_unset_mtime(struct archive_entry *); 262 __LA_DECL void archive_entry_set_nlink(struct archive_entry *, unsigned int); 263 __LA_DECL void archive_entry_set_pathname(struct archive_entry *, const char *); 264 __LA_DECL void archive_entry_copy_pathname(struct archive_entry *, const char *); 265 __LA_DECL void archive_entry_copy_pathname_w(struct archive_entry *, const wchar_t *); 266 __LA_DECL int archive_entry_update_pathname_utf8(struct archive_entry *, const char *); 267 __LA_DECL void archive_entry_set_perm(struct archive_entry *, __LA_MODE_T); 268 __LA_DECL void archive_entry_set_rdev(struct archive_entry *, dev_t); 269 __LA_DECL void archive_entry_set_rdevmajor(struct archive_entry *, dev_t); 270 __LA_DECL void archive_entry_set_rdevminor(struct archive_entry *, dev_t); 271 __LA_DECL void archive_entry_set_size(struct archive_entry *, __LA_INT64_T); 272 __LA_DECL void archive_entry_unset_size(struct archive_entry *); 273 __LA_DECL void archive_entry_copy_sourcepath(struct archive_entry *, const char *); 274 __LA_DECL void archive_entry_set_symlink(struct archive_entry *, const char *); 275 __LA_DECL void archive_entry_copy_symlink(struct archive_entry *, const char *); 276 __LA_DECL void archive_entry_copy_symlink_w(struct archive_entry *, const wchar_t *); 277 __LA_DECL void archive_entry_set_uid(struct archive_entry *, __LA_UID_T); 278 __LA_DECL void archive_entry_set_uname(struct archive_entry *, const char *); 279 __LA_DECL void archive_entry_copy_uname(struct archive_entry *, const char *); 280 __LA_DECL void archive_entry_copy_uname_w(struct archive_entry *, const wchar_t *); 281 __LA_DECL int archive_entry_update_uname_utf8(struct archive_entry *, const char *); 282 /* 283 * Routines to bulk copy fields to/from a platform-native "struct 284 * stat." Libarchive used to just store a struct stat inside of each 285 * archive_entry object, but this created issues when trying to 286 * manipulate archives on systems different than the ones they were 287 * created on. 288 * 289 * TODO: On Linux, provide both stat32 and stat64 versions of these functions. 290 */ 291 __LA_DECL const struct stat *archive_entry_stat(struct archive_entry *); 292 __LA_DECL void archive_entry_copy_stat(struct archive_entry *, const struct stat *); 293 294 295 /* 296 * ACL routines. This used to simply store and return text-format ACL 297 * strings, but that proved insufficient for a number of reasons: 298 * = clients need control over uname/uid and gname/gid mappings 299 * = there are many different ACL text formats 300 * = would like to be able to read/convert archives containing ACLs 301 * on platforms that lack ACL libraries 302 * 303 * This last point, in particular, forces me to implement a reasonably 304 * complete set of ACL support routines. 305 * 306 * TODO: Extend this to support NFSv4/NTFS permissions. That should 307 * allow full ACL support on Mac OS, in particular, which uses 308 * POSIX.1e-style interfaces to manipulate NFSv4/NTFS permissions. 309 */ 310 311 /* 312 * Permission bits mimic POSIX.1e. Note that I've not followed POSIX.1e's 313 * "permset"/"perm" abstract type nonsense. A permset is just a simple 314 * bitmap, following long-standing Unix tradition. 315 */ 316 #define ARCHIVE_ENTRY_ACL_EXECUTE 1 317 #define ARCHIVE_ENTRY_ACL_WRITE 2 318 #define ARCHIVE_ENTRY_ACL_READ 4 319 320 /* We need to be able to specify either or both of these. */ 321 #define ARCHIVE_ENTRY_ACL_TYPE_ACCESS 256 322 #define ARCHIVE_ENTRY_ACL_TYPE_DEFAULT 512 323 324 /* Tag values mimic POSIX.1e */ 325 #define ARCHIVE_ENTRY_ACL_USER 10001 /* Specified user. */ 326 #define ARCHIVE_ENTRY_ACL_USER_OBJ 10002 /* User who owns the file. */ 327 #define ARCHIVE_ENTRY_ACL_GROUP 10003 /* Specified group. */ 328 #define ARCHIVE_ENTRY_ACL_GROUP_OBJ 10004 /* Group who owns the file. */ 329 #define ARCHIVE_ENTRY_ACL_MASK 10005 /* Modify group access. */ 330 #define ARCHIVE_ENTRY_ACL_OTHER 10006 /* Public. */ 331 332 /* 333 * Set the ACL by clearing it and adding entries one at a time. 334 * Unlike the POSIX.1e ACL routines, you must specify the type 335 * (access/default) for each entry. Internally, the ACL data is just 336 * a soup of entries. API calls here allow you to retrieve just the 337 * entries of interest. This design (which goes against the spirit of 338 * POSIX.1e) is useful for handling archive formats that combine 339 * default and access information in a single ACL list. 340 */ 341 __LA_DECL void archive_entry_acl_clear(struct archive_entry *); 342 __LA_DECL void archive_entry_acl_add_entry(struct archive_entry *, 343 int /* type */, int /* permset */, int /* tag */, 344 int /* qual */, const char * /* name */); 345 __LA_DECL void archive_entry_acl_add_entry_w(struct archive_entry *, 346 int /* type */, int /* permset */, int /* tag */, 347 int /* qual */, const wchar_t * /* name */); 348 349 /* 350 * To retrieve the ACL, first "reset", then repeatedly ask for the 351 * "next" entry. The want_type parameter allows you to request only 352 * access entries or only default entries. 353 */ 354 __LA_DECL int archive_entry_acl_reset(struct archive_entry *, int /* want_type */); 355 __LA_DECL int archive_entry_acl_next(struct archive_entry *, int /* want_type */, 356 int * /* type */, int * /* permset */, int * /* tag */, 357 int * /* qual */, const char ** /* name */); 358 __LA_DECL int archive_entry_acl_next_w(struct archive_entry *, int /* want_type */, 359 int * /* type */, int * /* permset */, int * /* tag */, 360 int * /* qual */, const wchar_t ** /* name */); 361 362 /* 363 * Construct a text-format ACL. The flags argument is a bitmask that 364 * can include any of the following: 365 * 366 * ARCHIVE_ENTRY_ACL_TYPE_ACCESS - Include access entries. 367 * ARCHIVE_ENTRY_ACL_TYPE_DEFAULT - Include default entries. 368 * ARCHIVE_ENTRY_ACL_STYLE_EXTRA_ID - Include extra numeric ID field in 369 * each ACL entry. (As used by 'star'.) 370 * ARCHIVE_ENTRY_ACL_STYLE_MARK_DEFAULT - Include "default:" before each 371 * default ACL entry. 372 */ 373 #define ARCHIVE_ENTRY_ACL_STYLE_EXTRA_ID 1024 374 #define ARCHIVE_ENTRY_ACL_STYLE_MARK_DEFAULT 2048 375 __LA_DECL const wchar_t *archive_entry_acl_text_w(struct archive_entry *, 376 int /* flags */); 377 378 /* Return a count of entries matching 'want_type' */ 379 __LA_DECL int archive_entry_acl_count(struct archive_entry *, int /* want_type */); 380 381 /* 382 * Private ACL parser. This is private because it handles some 383 * very weird formats that clients should not be messing with. 384 * Clients should only deal with their platform-native formats. 385 * Because of the need to support many formats cleanly, new arguments 386 * are likely to get added on a regular basis. Clients who try to use 387 * this interface are likely to be surprised when it changes. 388 * 389 * You were warned! 390 * 391 * TODO: Move this declaration out of the public header and into 392 * a private header. Warnings above are silly. 393 */ 394 __LA_DECL int __archive_entry_acl_parse_w(struct archive_entry *, 395 const wchar_t *, int /* type */); 396 397 /* 398 * extended attributes 399 */ 400 401 __LA_DECL void archive_entry_xattr_clear(struct archive_entry *); 402 __LA_DECL void archive_entry_xattr_add_entry(struct archive_entry *, 403 const char * /* name */, const void * /* value */, 404 size_t /* size */); 405 406 /* 407 * To retrieve the xattr list, first "reset", then repeatedly ask for the 408 * "next" entry. 409 */ 410 411 __LA_DECL int archive_entry_xattr_count(struct archive_entry *); 412 __LA_DECL int archive_entry_xattr_reset(struct archive_entry *); 413 __LA_DECL int archive_entry_xattr_next(struct archive_entry *, 414 const char ** /* name */, const void ** /* value */, size_t *); 415 416 /* 417 * Utility to match up hardlinks. 418 * 419 * The 'struct archive_entry_linkresolver' is a cache of archive entries 420 * for files with multiple links. Here's how to use it: 421 * 1. Create a lookup object with archive_entry_linkresolver_new() 422 * 2. Tell it the archive format you're using. 423 * 3. Hand each archive_entry to archive_entry_linkify(). 424 * That function will return 0, 1, or 2 entries that should 425 * be written. 426 * 4. Call archive_entry_linkify(resolver, NULL) until 427 * no more entries are returned. 428 * 5. Call archive_entry_link_resolver_free(resolver) to free resources. 429 * 430 * The entries returned have their hardlink and size fields updated 431 * appropriately. If an entry is passed in that does not refer to 432 * a file with multiple links, it is returned unchanged. The intention 433 * is that you should be able to simply filter all entries through 434 * this machine. 435 * 436 * To make things more efficient, be sure that each entry has a valid 437 * nlinks value. The hardlink cache uses this to track when all links 438 * have been found. If the nlinks value is zero, it will keep every 439 * name in the cache indefinitely, which can use a lot of memory. 440 * 441 * Note that archive_entry_size() is reset to zero if the file 442 * body should not be written to the archive. Pay attention! 443 */ 444 struct archive_entry_linkresolver; 445 446 /* 447 * There are three different strategies for marking hardlinks. 448 * The descriptions below name them after the best-known 449 * formats that rely on each strategy: 450 * 451 * "Old cpio" is the simplest, it always returns any entry unmodified. 452 * As far as I know, only cpio formats use this. Old cpio archives 453 * store every link with the full body; the onus is on the dearchiver 454 * to detect and properly link the files as they are restored. 455 * "tar" is also pretty simple; it caches a copy the first time it sees 456 * any link. Subsequent appearances are modified to be hardlink 457 * references to the first one without any body. Used by all tar 458 * formats, although the newest tar formats permit the "old cpio" strategy 459 * as well. This strategy is very simple for the dearchiver, 460 * and reasonably straightforward for the archiver. 461 * "new cpio" is trickier. It stores the body only with the last 462 * occurrence. The complication is that we might not 463 * see every link to a particular file in a single session, so 464 * there's no easy way to know when we've seen the last occurrence. 465 * The solution here is to queue one link until we see the next. 466 * At the end of the session, you can enumerate any remaining 467 * entries by calling archive_entry_linkify(NULL) and store those 468 * bodies. If you have a file with three links l1, l2, and l3, 469 * you'll get the following behavior if you see all three links: 470 * linkify(l1) => NULL (the resolver stores l1 internally) 471 * linkify(l2) => l1 (resolver stores l2, you write l1) 472 * linkify(l3) => l2, l3 (all links seen, you can write both). 473 * If you only see l1 and l2, you'll get this behavior: 474 * linkify(l1) => NULL 475 * linkify(l2) => l1 476 * linkify(NULL) => l2 (at end, you retrieve remaining links) 477 * As the name suggests, this strategy is used by newer cpio variants. 478 * It's noticably more complex for the archiver, slightly more complex 479 * for the dearchiver than the tar strategy, but makes it straightforward 480 * to restore a file using any link by simply continuing to scan until 481 * you see a link that is stored with a body. In contrast, the tar 482 * strategy requires you to rescan the archive from the beginning to 483 * correctly extract an arbitrary link. 484 */ 485 486 __LA_DECL struct archive_entry_linkresolver *archive_entry_linkresolver_new(void); 487 __LA_DECL void archive_entry_linkresolver_set_strategy( 488 struct archive_entry_linkresolver *, int /* format_code */); 489 __LA_DECL void archive_entry_linkresolver_free(struct archive_entry_linkresolver *); 490 __LA_DECL void archive_entry_linkify(struct archive_entry_linkresolver *, 491 struct archive_entry **, struct archive_entry **); 492 493 #ifdef __cplusplus 494 } 495 #endif 496 497 /* This is meaningless outside of this header. */ 498 #undef __LA_DECL 499 500 #endif /* !ARCHIVE_ENTRY_H_INCLUDED */ 501