Contents of /trunk/mkinitrd-magellan/busybox/archival/libunarchive/get_header_tar.c
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Sun May 30 11:32:42 2010 UTC (14 years, 3 months ago) by niro
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File size: 13922 byte(s)
Sun May 30 11:32:42 2010 UTC (14 years, 3 months ago) by niro
File MIME type: text/plain
File size: 13922 byte(s)
-updated to busybox-1.16.1 and enabled blkid/uuid support in default config
1 | /* vi: set sw=4 ts=4: */ |
2 | /* Licensed under GPLv2 or later, see file LICENSE in this tarball for details. |
3 | * |
4 | * FIXME: |
5 | * In privileged mode if uname and gname map to a uid and gid then use the |
6 | * mapped value instead of the uid/gid values in tar header |
7 | * |
8 | * References: |
9 | * GNU tar and star man pages, |
10 | * Opengroup's ustar interchange format, |
11 | * http://www.opengroup.org/onlinepubs/007904975/utilities/pax.html |
12 | */ |
13 | |
14 | #include "libbb.h" |
15 | #include "unarchive.h" |
16 | |
17 | /* |
18 | * GNU tar uses "base-256 encoding" for very large numbers (>8 billion). |
19 | * Encoding is binary, with highest bit always set as a marker |
20 | * and sign in next-highest bit: |
21 | * 80 00 .. 00 - zero |
22 | * bf ff .. ff - largest positive number |
23 | * ff ff .. ff - minus 1 |
24 | * c0 00 .. 00 - smallest negative number |
25 | * |
26 | * We expect it only in size field, where negative numbers don't make sense. |
27 | */ |
28 | static off_t getBase256_len12(const char *str) |
29 | { |
30 | off_t value; |
31 | int len; |
32 | |
33 | /* if (*str & 0x40) error; - caller prevents this */ |
34 | |
35 | if (sizeof(off_t) >= 12) { |
36 | /* Probably 128-bit (16 byte) off_t. Can be optimized. */ |
37 | len = 12; |
38 | value = *str++ & 0x3f; |
39 | while (--len) |
40 | value = (value << 8) + (unsigned char) *str++; |
41 | return value; |
42 | } |
43 | |
44 | #ifdef CHECK_FOR_OVERFLOW |
45 | /* Can be optimized to eat 32-bit chunks */ |
46 | char c = *str++ & 0x3f; |
47 | len = 12; |
48 | while (1) { |
49 | if (c) |
50 | bb_error_msg_and_die("overflow in base-256 encoded file size"); |
51 | if (--len == sizeof(off_t)) |
52 | break; |
53 | c = *str++; |
54 | } |
55 | #else |
56 | str += (12 - sizeof(off_t)); |
57 | #endif |
58 | |
59 | /* Now str points to sizeof(off_t) least significant bytes. |
60 | * |
61 | * Example of tar file with 8914993153 (0x213600001) byte file. |
62 | * Field starts at offset 7c: |
63 | * 00070 30 30 30 00 30 30 30 30 30 30 30 00 80 00 00 00 |000.0000000.....| |
64 | * 00080 00 00 00 02 13 60 00 01 31 31 31 32 30 33 33 36 |.....`..11120336| |
65 | * |
66 | * str is at offset 80 or 84 now (64-bit or 32-bit off_t). |
67 | * We (ab)use the fact that value happens to be aligned, |
68 | * and fetch it in one go: |
69 | */ |
70 | if (sizeof(off_t) == 8) { |
71 | value = *(off_t*)str; |
72 | value = SWAP_BE64(value); |
73 | } else if (sizeof(off_t) == 4) { |
74 | value = *(off_t*)str; |
75 | value = SWAP_BE32(value); |
76 | } else { |
77 | value = 0; |
78 | len = sizeof(off_t); |
79 | while (--len) |
80 | value = (value << 8) + (unsigned char) *str++; |
81 | } |
82 | return value; |
83 | } |
84 | |
85 | /* NB: _DESTROYS_ str[len] character! */ |
86 | static unsigned long long getOctal(char *str, int len) |
87 | { |
88 | unsigned long long v; |
89 | /* NB: leading spaces are allowed. Using strtoull to handle that. |
90 | * The downside is that we accept e.g. "-123" too :( |
91 | */ |
92 | str[len] = '\0'; |
93 | v = strtoull(str, &str, 8); |
94 | /* std: "Each numeric field is terminated by one or more |
95 | * <space> or NUL characters". We must support ' '! */ |
96 | if (*str != '\0' && *str != ' ') |
97 | bb_error_msg_and_die("corrupted octal value in tar header"); |
98 | return v; |
99 | } |
100 | #define GET_OCTAL(a) getOctal((a), sizeof(a)) |
101 | |
102 | void BUG_tar_header_size(void); |
103 | char FAST_FUNC get_header_tar(archive_handle_t *archive_handle) |
104 | { |
105 | file_header_t *file_header = archive_handle->file_header; |
106 | struct { |
107 | /* ustar header, Posix 1003.1 */ |
108 | char name[100]; /* 0-99 */ |
109 | char mode[8]; /* 100-107 */ |
110 | char uid[8]; /* 108-115 */ |
111 | char gid[8]; /* 116-123 */ |
112 | char size[12]; /* 124-135 */ |
113 | char mtime[12]; /* 136-147 */ |
114 | char chksum[8]; /* 148-155 */ |
115 | char typeflag; /* 156-156 */ |
116 | char linkname[100]; /* 157-256 */ |
117 | /* POSIX: "ustar" NUL "00" */ |
118 | /* GNU tar: "ustar " NUL */ |
119 | /* Normally it's defined as magic[6] followed by |
120 | * version[2], but we put them together to simplify code |
121 | */ |
122 | char magic[8]; /* 257-264 */ |
123 | char uname[32]; /* 265-296 */ |
124 | char gname[32]; /* 297-328 */ |
125 | char devmajor[8]; /* 329-336 */ |
126 | char devminor[8]; /* 337-344 */ |
127 | char prefix[155]; /* 345-499 */ |
128 | char padding[12]; /* 500-512 */ |
129 | } tar; |
130 | char *cp; |
131 | int i, sum_u, sum; |
132 | #if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY |
133 | int sum_s; |
134 | #endif |
135 | int parse_names; |
136 | |
137 | /* Our "private data" */ |
138 | #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS |
139 | # define p_longname (archive_handle->tar__longname) |
140 | # define p_linkname (archive_handle->tar__linkname) |
141 | #else |
142 | # define p_longname 0 |
143 | # define p_linkname 0 |
144 | #endif |
145 | |
146 | if (sizeof(tar) != 512) |
147 | BUG_tar_header_size(); |
148 | |
149 | #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS |
150 | again: |
151 | #endif |
152 | /* Align header */ |
153 | data_align(archive_handle, 512); |
154 | |
155 | again_after_align: |
156 | |
157 | #if ENABLE_DESKTOP || ENABLE_FEATURE_TAR_AUTODETECT |
158 | /* to prevent misdetection of bz2 sig */ |
159 | *(uint32_t*)(&tar) = 0; |
160 | i = full_read(archive_handle->src_fd, &tar, 512); |
161 | /* If GNU tar sees EOF in above read, it says: |
162 | * "tar: A lone zero block at N", where N = kilobyte |
163 | * where EOF was met (not EOF block, actual EOF!), |
164 | * and exits with EXIT_SUCCESS. |
165 | * We will mimic exit(EXIT_SUCCESS), although we will not mimic |
166 | * the message and we don't check whether we indeed |
167 | * saw zero block directly before this. */ |
168 | if (i == 0) { |
169 | xfunc_error_retval = 0; |
170 | short_read: |
171 | bb_error_msg_and_die("short read"); |
172 | } |
173 | if (i != 512) { |
174 | IF_FEATURE_TAR_AUTODETECT(goto autodetect;) |
175 | goto short_read; |
176 | } |
177 | |
178 | #else |
179 | i = 512; |
180 | xread(archive_handle->src_fd, &tar, i); |
181 | #endif |
182 | archive_handle->offset += i; |
183 | |
184 | /* If there is no filename its an empty header */ |
185 | if (tar.name[0] == 0 && tar.prefix[0] == 0) { |
186 | if (archive_handle->tar__end) { |
187 | /* Second consecutive empty header - end of archive. |
188 | * Read until the end to empty the pipe from gz or bz2 |
189 | */ |
190 | while (full_read(archive_handle->src_fd, &tar, 512) == 512) |
191 | continue; |
192 | return EXIT_FAILURE; |
193 | } |
194 | archive_handle->tar__end = 1; |
195 | return EXIT_SUCCESS; |
196 | } |
197 | archive_handle->tar__end = 0; |
198 | |
199 | /* Check header has valid magic, "ustar" is for the proper tar, |
200 | * five NULs are for the old tar format */ |
201 | if (strncmp(tar.magic, "ustar", 5) != 0 |
202 | && (!ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY |
203 | || memcmp(tar.magic, "\0\0\0\0", 5) != 0) |
204 | ) { |
205 | #if ENABLE_FEATURE_TAR_AUTODETECT |
206 | char FAST_FUNC (*get_header_ptr)(archive_handle_t *); |
207 | |
208 | autodetect: |
209 | /* tar gz/bz autodetect: check for gz/bz2 magic. |
210 | * If we see the magic, and it is the very first block, |
211 | * we can switch to get_header_tar_gz/bz2/lzma(). |
212 | * Needs seekable fd. I wish recv(MSG_PEEK) works |
213 | * on any fd... */ |
214 | #if ENABLE_FEATURE_SEAMLESS_GZ |
215 | if (tar.name[0] == 0x1f && tar.name[1] == (char)0x8b) { /* gzip */ |
216 | get_header_ptr = get_header_tar_gz; |
217 | } else |
218 | #endif |
219 | #if ENABLE_FEATURE_SEAMLESS_BZ2 |
220 | if (tar.name[0] == 'B' && tar.name[1] == 'Z' |
221 | && tar.name[2] == 'h' && isdigit(tar.name[3]) |
222 | ) { /* bzip2 */ |
223 | get_header_ptr = get_header_tar_bz2; |
224 | } else |
225 | #endif |
226 | goto err; |
227 | /* Two different causes for lseek() != 0: |
228 | * unseekable fd (would like to support that too, but...), |
229 | * or not first block (false positive, it's not .gz/.bz2!) */ |
230 | if (lseek(archive_handle->src_fd, -i, SEEK_CUR) != 0) |
231 | goto err; |
232 | while (get_header_ptr(archive_handle) == EXIT_SUCCESS) |
233 | continue; |
234 | return EXIT_FAILURE; |
235 | err: |
236 | #endif /* FEATURE_TAR_AUTODETECT */ |
237 | bb_error_msg_and_die("invalid tar magic"); |
238 | } |
239 | |
240 | /* Do checksum on headers. |
241 | * POSIX says that checksum is done on unsigned bytes, but |
242 | * Sun and HP-UX gets it wrong... more details in |
243 | * GNU tar source. */ |
244 | #if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY |
245 | sum_s = ' ' * sizeof(tar.chksum); |
246 | #endif |
247 | sum_u = ' ' * sizeof(tar.chksum); |
248 | for (i = 0; i < 148; i++) { |
249 | sum_u += ((unsigned char*)&tar)[i]; |
250 | #if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY |
251 | sum_s += ((signed char*)&tar)[i]; |
252 | #endif |
253 | } |
254 | for (i = 156; i < 512; i++) { |
255 | sum_u += ((unsigned char*)&tar)[i]; |
256 | #if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY |
257 | sum_s += ((signed char*)&tar)[i]; |
258 | #endif |
259 | } |
260 | /* This field does not need special treatment (getOctal) */ |
261 | { |
262 | char *endp; /* gcc likes temp var for &endp */ |
263 | sum = strtoul(tar.chksum, &endp, 8); |
264 | if ((*endp != '\0' && *endp != ' ') |
265 | || (sum_u != sum IF_FEATURE_TAR_OLDSUN_COMPATIBILITY(&& sum_s != sum)) |
266 | ) { |
267 | bb_error_msg_and_die("invalid tar header checksum"); |
268 | } |
269 | } |
270 | /* don't use xstrtoul, tar.chksum may have leading spaces */ |
271 | sum = strtoul(tar.chksum, NULL, 8); |
272 | if (sum_u != sum IF_FEATURE_TAR_OLDSUN_COMPATIBILITY(&& sum_s != sum)) { |
273 | bb_error_msg_and_die("invalid tar header checksum"); |
274 | } |
275 | |
276 | /* 0 is reserved for high perf file, treat as normal file */ |
277 | if (!tar.typeflag) tar.typeflag = '0'; |
278 | parse_names = (tar.typeflag >= '0' && tar.typeflag <= '7'); |
279 | |
280 | /* getOctal trashes subsequent field, therefore we call it |
281 | * on fields in reverse order */ |
282 | if (tar.devmajor[0]) { |
283 | char t = tar.prefix[0]; |
284 | /* we trash prefix[0] here, but we DO need it later! */ |
285 | unsigned minor = GET_OCTAL(tar.devminor); |
286 | unsigned major = GET_OCTAL(tar.devmajor); |
287 | file_header->device = makedev(major, minor); |
288 | tar.prefix[0] = t; |
289 | } |
290 | file_header->link_target = NULL; |
291 | if (!p_linkname && parse_names && tar.linkname[0]) { |
292 | file_header->link_target = xstrndup(tar.linkname, sizeof(tar.linkname)); |
293 | /* FIXME: what if we have non-link object with link_target? */ |
294 | /* Will link_target be free()ed? */ |
295 | } |
296 | #if ENABLE_FEATURE_TAR_UNAME_GNAME |
297 | file_header->tar__uname = tar.uname[0] ? xstrndup(tar.uname, sizeof(tar.uname)) : NULL; |
298 | file_header->tar__gname = tar.gname[0] ? xstrndup(tar.gname, sizeof(tar.gname)) : NULL; |
299 | #endif |
300 | /* mtime: rudimentally handle GNU tar's "base256 encoding" |
301 | * People report tarballs with NEGATIVE unix times encoded that way */ |
302 | file_header->mtime = (tar.mtime[0] & 0x80) /* base256? */ |
303 | ? 0 /* bogus */ |
304 | : GET_OCTAL(tar.mtime); |
305 | /* size: handle GNU tar's "base256 encoding" */ |
306 | file_header->size = (tar.size[0] & 0xc0) == 0x80 /* positive base256? */ |
307 | ? getBase256_len12(tar.size) |
308 | : GET_OCTAL(tar.size); |
309 | file_header->gid = GET_OCTAL(tar.gid); |
310 | file_header->uid = GET_OCTAL(tar.uid); |
311 | /* Set bits 0-11 of the files mode */ |
312 | file_header->mode = 07777 & GET_OCTAL(tar.mode); |
313 | |
314 | file_header->name = NULL; |
315 | if (!p_longname && parse_names) { |
316 | /* we trash mode[0] here, it's ok */ |
317 | //tar.name[sizeof(tar.name)] = '\0'; - gcc 4.3.0 would complain |
318 | tar.mode[0] = '\0'; |
319 | if (tar.prefix[0]) { |
320 | /* and padding[0] */ |
321 | //tar.prefix[sizeof(tar.prefix)] = '\0'; - gcc 4.3.0 would complain |
322 | tar.padding[0] = '\0'; |
323 | file_header->name = concat_path_file(tar.prefix, tar.name); |
324 | } else |
325 | file_header->name = xstrdup(tar.name); |
326 | } |
327 | |
328 | /* Set bits 12-15 of the files mode */ |
329 | /* (typeflag was not trashed because chksum does not use getOctal) */ |
330 | switch (tar.typeflag) { |
331 | /* busybox identifies hard links as being regular files with 0 size and a link name */ |
332 | case '1': |
333 | file_header->mode |= S_IFREG; |
334 | break; |
335 | case '7': |
336 | /* case 0: */ |
337 | case '0': |
338 | #if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY |
339 | if (last_char_is(file_header->name, '/')) { |
340 | goto set_dir; |
341 | } |
342 | #endif |
343 | file_header->mode |= S_IFREG; |
344 | break; |
345 | case '2': |
346 | file_header->mode |= S_IFLNK; |
347 | /* have seen tarballs with size field containing |
348 | * the size of the link target's name */ |
349 | size0: |
350 | file_header->size = 0; |
351 | break; |
352 | case '3': |
353 | file_header->mode |= S_IFCHR; |
354 | goto size0; /* paranoia */ |
355 | case '4': |
356 | file_header->mode |= S_IFBLK; |
357 | goto size0; |
358 | case '5': |
359 | IF_FEATURE_TAR_OLDGNU_COMPATIBILITY(set_dir:) |
360 | file_header->mode |= S_IFDIR; |
361 | goto size0; |
362 | case '6': |
363 | file_header->mode |= S_IFIFO; |
364 | goto size0; |
365 | #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS |
366 | case 'L': |
367 | /* free: paranoia: tar with several consecutive longnames */ |
368 | free(p_longname); |
369 | /* For paranoia reasons we allocate extra NUL char */ |
370 | p_longname = xzalloc(file_header->size + 1); |
371 | /* We read ASCIZ string, including NUL */ |
372 | xread(archive_handle->src_fd, p_longname, file_header->size); |
373 | archive_handle->offset += file_header->size; |
374 | /* return get_header_tar(archive_handle); */ |
375 | /* gcc 4.1.1 didn't optimize it into jump */ |
376 | /* so we will do it ourself, this also saves stack */ |
377 | goto again; |
378 | case 'K': |
379 | free(p_linkname); |
380 | p_linkname = xzalloc(file_header->size + 1); |
381 | xread(archive_handle->src_fd, p_linkname, file_header->size); |
382 | archive_handle->offset += file_header->size; |
383 | /* return get_header_tar(archive_handle); */ |
384 | goto again; |
385 | case 'D': /* GNU dump dir */ |
386 | case 'M': /* Continuation of multi volume archive */ |
387 | case 'N': /* Old GNU for names > 100 characters */ |
388 | case 'S': /* Sparse file */ |
389 | case 'V': /* Volume header */ |
390 | #endif |
391 | case 'g': /* pax global header */ |
392 | case 'x': { /* pax extended header */ |
393 | off_t sz; |
394 | bb_error_msg("warning: skipping header '%c'", tar.typeflag); |
395 | sz = (file_header->size + 511) & ~(off_t)511; |
396 | archive_handle->offset += sz; |
397 | sz >>= 9; /* sz /= 512 but w/o contortions for signed div */ |
398 | while (sz--) |
399 | xread(archive_handle->src_fd, &tar, 512); |
400 | /* return get_header_tar(archive_handle); */ |
401 | goto again_after_align; |
402 | } |
403 | default: |
404 | bb_error_msg_and_die("unknown typeflag: 0x%x", tar.typeflag); |
405 | } |
406 | |
407 | #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS |
408 | if (p_longname) { |
409 | file_header->name = p_longname; |
410 | p_longname = NULL; |
411 | } |
412 | if (p_linkname) { |
413 | file_header->link_target = p_linkname; |
414 | p_linkname = NULL; |
415 | } |
416 | #endif |
417 | if (strncmp(file_header->name, "/../"+1, 3) == 0 |
418 | || strstr(file_header->name, "/../") |
419 | ) { |
420 | bb_error_msg_and_die("name with '..' encountered: '%s'", |
421 | file_header->name); |
422 | } |
423 | |
424 | /* Strip trailing '/' in directories */ |
425 | /* Must be done after mode is set as '/' is used to check if it's a directory */ |
426 | cp = last_char_is(file_header->name, '/'); |
427 | |
428 | if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) { |
429 | archive_handle->action_header(/*archive_handle->*/ file_header); |
430 | /* Note that we kill the '/' only after action_header() */ |
431 | /* (like GNU tar 1.15.1: verbose mode outputs "dir/dir/") */ |
432 | if (cp) *cp = '\0'; |
433 | archive_handle->ah_flags |= ARCHIVE_EXTRACT_QUIET; |
434 | archive_handle->action_data(archive_handle); |
435 | llist_add_to(&(archive_handle->passed), file_header->name); |
436 | } else { |
437 | data_skip(archive_handle); |
438 | free(file_header->name); |
439 | } |
440 | archive_handle->offset += file_header->size; |
441 | |
442 | free(file_header->link_target); |
443 | /* Do not free(file_header->name)! (why?) */ |
444 | #if ENABLE_FEATURE_TAR_UNAME_GNAME |
445 | free(file_header->tar__uname); |
446 | free(file_header->tar__gname); |
447 | #endif |
448 | return EXIT_SUCCESS; |
449 | } |