Contents of /trunk/mkinitrd-magellan/busybox/archival/libunarchive/get_header_tar.c
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Wed Aug 18 21:56:57 2010 UTC (13 years, 9 months ago) by niro
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Wed Aug 18 21:56:57 2010 UTC (13 years, 9 months ago) by niro
File MIME type: text/plain
File size: 14235 byte(s)
-updated to busybox-1.17.1
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 | typedef uint32_t aliased_uint32_t FIX_ALIASING; |
18 | typedef off_t aliased_off_t FIX_ALIASING; |
19 | |
20 | |
21 | /* NB: _DESTROYS_ str[len] character! */ |
22 | static unsigned long long getOctal(char *str, int len) |
23 | { |
24 | unsigned long long v; |
25 | char *end; |
26 | /* NB: leading spaces are allowed. Using strtoull to handle that. |
27 | * The downside is that we accept e.g. "-123" too :( |
28 | */ |
29 | str[len] = '\0'; |
30 | v = strtoull(str, &end, 8); |
31 | /* std: "Each numeric field is terminated by one or more |
32 | * <space> or NUL characters". We must support ' '! */ |
33 | if (*end != '\0' && *end != ' ') { |
34 | int8_t first = str[0]; |
35 | if (!(first & 0x80)) |
36 | bb_error_msg_and_die("corrupted octal value in tar header"); |
37 | /* |
38 | * GNU tar uses "base-256 encoding" for very large numbers. |
39 | * Encoding is binary, with highest bit always set as a marker |
40 | * and sign in next-highest bit: |
41 | * 80 00 .. 00 - zero |
42 | * bf ff .. ff - largest positive number |
43 | * ff ff .. ff - minus 1 |
44 | * c0 00 .. 00 - smallest negative number |
45 | * |
46 | * Example of tar file with 8914993153 (0x213600001) byte file. |
47 | * Field starts at offset 7c: |
48 | * 00070 30 30 30 00 30 30 30 30 30 30 30 00 80 00 00 00 |000.0000000.....| |
49 | * 00080 00 00 00 02 13 60 00 01 31 31 31 32 30 33 33 36 |.....`..11120336| |
50 | * |
51 | * NB: tarballs with NEGATIVE unix times encoded that way were seen! |
52 | */ |
53 | v = first; |
54 | /* Sign-extend using 6th bit: */ |
55 | v <<= sizeof(unsigned long long)*8 - 7; |
56 | v = (long long)v >> (sizeof(unsigned long long)*8 - 7); |
57 | while (--len != 0) |
58 | v = (v << 8) + (unsigned char) *str++; |
59 | } |
60 | return v; |
61 | } |
62 | #define GET_OCTAL(a) getOctal((a), sizeof(a)) |
63 | |
64 | #if ENABLE_FEATURE_TAR_SELINUX |
65 | /* Scan a PAX header for SELinux contexts, via "RHT.security.selinux" keyword. |
66 | * This is what Red Hat's patched version of tar uses. |
67 | */ |
68 | # define SELINUX_CONTEXT_KEYWORD "RHT.security.selinux" |
69 | static char *get_selinux_sctx_from_pax_hdr(archive_handle_t *archive_handle, unsigned sz) |
70 | { |
71 | char *buf, *p; |
72 | char *result; |
73 | |
74 | p = buf = xmalloc(sz + 1); |
75 | /* prevent bb_strtou from running off the buffer */ |
76 | buf[sz] = '\0'; |
77 | xread(archive_handle->src_fd, buf, sz); |
78 | archive_handle->offset += sz; |
79 | |
80 | result = NULL; |
81 | while (sz != 0) { |
82 | char *end, *value; |
83 | unsigned len; |
84 | |
85 | /* Every record has this format: "LEN NAME=VALUE\n" */ |
86 | len = bb_strtou(p, &end, 10); |
87 | /* expect errno to be EINVAL, because the character |
88 | * following the digits should be a space |
89 | */ |
90 | p += len; |
91 | sz -= len; |
92 | if ((int)sz < 0 |
93 | || len == 0 |
94 | || errno != EINVAL |
95 | || *end != ' ' |
96 | ) { |
97 | bb_error_msg("malformed extended header, skipped"); |
98 | // More verbose version: |
99 | //bb_error_msg("malformed extended header at %"OFF_FMT"d, skipped", |
100 | // archive_handle->offset - (sz + len)); |
101 | break; |
102 | } |
103 | /* overwrite the terminating newline with NUL |
104 | * (we do not bother to check that it *was* a newline) |
105 | */ |
106 | p[-1] = '\0'; |
107 | /* Is it selinux security context? */ |
108 | value = end + 1; |
109 | if (strncmp(value, SELINUX_CONTEXT_KEYWORD"=", sizeof(SELINUX_CONTEXT_KEYWORD"=") - 1) == 0) { |
110 | value += sizeof(SELINUX_CONTEXT_KEYWORD"=") - 1; |
111 | result = xstrdup(value); |
112 | break; |
113 | } |
114 | } |
115 | |
116 | free(buf); |
117 | return result; |
118 | } |
119 | #endif |
120 | |
121 | char FAST_FUNC get_header_tar(archive_handle_t *archive_handle) |
122 | { |
123 | file_header_t *file_header = archive_handle->file_header; |
124 | struct tar_header_t tar; |
125 | char *cp; |
126 | int i, sum_u, sum; |
127 | #if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY |
128 | int sum_s; |
129 | #endif |
130 | int parse_names; |
131 | |
132 | /* Our "private data" */ |
133 | #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS |
134 | # define p_longname (archive_handle->tar__longname) |
135 | # define p_linkname (archive_handle->tar__linkname) |
136 | #else |
137 | # define p_longname 0 |
138 | # define p_linkname 0 |
139 | #endif |
140 | |
141 | #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS || ENABLE_FEATURE_TAR_SELINUX |
142 | again: |
143 | #endif |
144 | /* Align header */ |
145 | data_align(archive_handle, 512); |
146 | |
147 | again_after_align: |
148 | |
149 | #if ENABLE_DESKTOP || ENABLE_FEATURE_TAR_AUTODETECT |
150 | /* to prevent misdetection of bz2 sig */ |
151 | *(aliased_uint32_t*)&tar = 0; |
152 | i = full_read(archive_handle->src_fd, &tar, 512); |
153 | /* If GNU tar sees EOF in above read, it says: |
154 | * "tar: A lone zero block at N", where N = kilobyte |
155 | * where EOF was met (not EOF block, actual EOF!), |
156 | * and exits with EXIT_SUCCESS. |
157 | * We will mimic exit(EXIT_SUCCESS), although we will not mimic |
158 | * the message and we don't check whether we indeed |
159 | * saw zero block directly before this. */ |
160 | if (i == 0) { |
161 | xfunc_error_retval = 0; |
162 | short_read: |
163 | bb_error_msg_and_die("short read"); |
164 | } |
165 | if (i != 512) { |
166 | IF_FEATURE_TAR_AUTODETECT(goto autodetect;) |
167 | goto short_read; |
168 | } |
169 | |
170 | #else |
171 | i = 512; |
172 | xread(archive_handle->src_fd, &tar, i); |
173 | #endif |
174 | archive_handle->offset += i; |
175 | |
176 | /* If there is no filename its an empty header */ |
177 | if (tar.name[0] == 0 && tar.prefix[0] == 0) { |
178 | if (archive_handle->tar__end) { |
179 | /* Second consecutive empty header - end of archive. |
180 | * Read until the end to empty the pipe from gz or bz2 |
181 | */ |
182 | while (full_read(archive_handle->src_fd, &tar, 512) == 512) |
183 | continue; |
184 | return EXIT_FAILURE; |
185 | } |
186 | archive_handle->tar__end = 1; |
187 | return EXIT_SUCCESS; |
188 | } |
189 | archive_handle->tar__end = 0; |
190 | |
191 | /* Check header has valid magic, "ustar" is for the proper tar, |
192 | * five NULs are for the old tar format */ |
193 | if (strncmp(tar.magic, "ustar", 5) != 0 |
194 | && (!ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY |
195 | || memcmp(tar.magic, "\0\0\0\0", 5) != 0) |
196 | ) { |
197 | #if ENABLE_FEATURE_TAR_AUTODETECT |
198 | char FAST_FUNC (*get_header_ptr)(archive_handle_t *); |
199 | uint16_t magic2; |
200 | |
201 | autodetect: |
202 | magic2 = *(uint16_t*)tar.name; |
203 | /* tar gz/bz autodetect: check for gz/bz2 magic. |
204 | * If we see the magic, and it is the very first block, |
205 | * we can switch to get_header_tar_gz/bz2/lzma(). |
206 | * Needs seekable fd. I wish recv(MSG_PEEK) works |
207 | * on any fd... */ |
208 | # if ENABLE_FEATURE_SEAMLESS_GZ |
209 | if (magic2 == GZIP_MAGIC) { |
210 | get_header_ptr = get_header_tar_gz; |
211 | } else |
212 | # endif |
213 | # if ENABLE_FEATURE_SEAMLESS_BZ2 |
214 | if (magic2 == BZIP2_MAGIC |
215 | && tar.name[2] == 'h' && isdigit(tar.name[3]) |
216 | ) { /* bzip2 */ |
217 | get_header_ptr = get_header_tar_bz2; |
218 | } else |
219 | # endif |
220 | # if ENABLE_FEATURE_SEAMLESS_XZ |
221 | //TODO: if (magic2 == XZ_MAGIC1)... |
222 | //else |
223 | # endif |
224 | goto err; |
225 | /* Two different causes for lseek() != 0: |
226 | * unseekable fd (would like to support that too, but...), |
227 | * or not first block (false positive, it's not .gz/.bz2!) */ |
228 | if (lseek(archive_handle->src_fd, -i, SEEK_CUR) != 0) |
229 | goto err; |
230 | while (get_header_ptr(archive_handle) == EXIT_SUCCESS) |
231 | continue; |
232 | return EXIT_FAILURE; |
233 | err: |
234 | #endif /* FEATURE_TAR_AUTODETECT */ |
235 | bb_error_msg_and_die("invalid tar magic"); |
236 | } |
237 | |
238 | /* Do checksum on headers. |
239 | * POSIX says that checksum is done on unsigned bytes, but |
240 | * Sun and HP-UX gets it wrong... more details in |
241 | * GNU tar source. */ |
242 | #if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY |
243 | sum_s = ' ' * sizeof(tar.chksum); |
244 | #endif |
245 | sum_u = ' ' * sizeof(tar.chksum); |
246 | for (i = 0; i < 148; i++) { |
247 | sum_u += ((unsigned char*)&tar)[i]; |
248 | #if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY |
249 | sum_s += ((signed char*)&tar)[i]; |
250 | #endif |
251 | } |
252 | for (i = 156; i < 512; i++) { |
253 | sum_u += ((unsigned char*)&tar)[i]; |
254 | #if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY |
255 | sum_s += ((signed char*)&tar)[i]; |
256 | #endif |
257 | } |
258 | /* This field does not need special treatment (getOctal) */ |
259 | { |
260 | char *endp; /* gcc likes temp var for &endp */ |
261 | sum = strtoul(tar.chksum, &endp, 8); |
262 | if ((*endp != '\0' && *endp != ' ') |
263 | || (sum_u != sum IF_FEATURE_TAR_OLDSUN_COMPATIBILITY(&& sum_s != sum)) |
264 | ) { |
265 | bb_error_msg_and_die("invalid tar header checksum"); |
266 | } |
267 | } |
268 | /* don't use xstrtoul, tar.chksum may have leading spaces */ |
269 | sum = strtoul(tar.chksum, NULL, 8); |
270 | if (sum_u != sum IF_FEATURE_TAR_OLDSUN_COMPATIBILITY(&& sum_s != sum)) { |
271 | bb_error_msg_and_die("invalid tar header checksum"); |
272 | } |
273 | |
274 | /* 0 is reserved for high perf file, treat as normal file */ |
275 | if (!tar.typeflag) tar.typeflag = '0'; |
276 | parse_names = (tar.typeflag >= '0' && tar.typeflag <= '7'); |
277 | |
278 | /* getOctal trashes subsequent field, therefore we call it |
279 | * on fields in reverse order */ |
280 | if (tar.devmajor[0]) { |
281 | char t = tar.prefix[0]; |
282 | /* we trash prefix[0] here, but we DO need it later! */ |
283 | unsigned minor = GET_OCTAL(tar.devminor); |
284 | unsigned major = GET_OCTAL(tar.devmajor); |
285 | file_header->device = makedev(major, minor); |
286 | tar.prefix[0] = t; |
287 | } |
288 | file_header->link_target = NULL; |
289 | if (!p_linkname && parse_names && tar.linkname[0]) { |
290 | file_header->link_target = xstrndup(tar.linkname, sizeof(tar.linkname)); |
291 | /* FIXME: what if we have non-link object with link_target? */ |
292 | /* Will link_target be free()ed? */ |
293 | } |
294 | #if ENABLE_FEATURE_TAR_UNAME_GNAME |
295 | file_header->tar__uname = tar.uname[0] ? xstrndup(tar.uname, sizeof(tar.uname)) : NULL; |
296 | file_header->tar__gname = tar.gname[0] ? xstrndup(tar.gname, sizeof(tar.gname)) : NULL; |
297 | #endif |
298 | file_header->mtime = GET_OCTAL(tar.mtime); |
299 | file_header->size = GET_OCTAL(tar.size); |
300 | file_header->gid = GET_OCTAL(tar.gid); |
301 | file_header->uid = GET_OCTAL(tar.uid); |
302 | /* Set bits 0-11 of the files mode */ |
303 | file_header->mode = 07777 & GET_OCTAL(tar.mode); |
304 | |
305 | file_header->name = NULL; |
306 | if (!p_longname && parse_names) { |
307 | /* we trash mode[0] here, it's ok */ |
308 | //tar.name[sizeof(tar.name)] = '\0'; - gcc 4.3.0 would complain |
309 | tar.mode[0] = '\0'; |
310 | if (tar.prefix[0]) { |
311 | /* and padding[0] */ |
312 | //tar.prefix[sizeof(tar.prefix)] = '\0'; - gcc 4.3.0 would complain |
313 | tar.padding[0] = '\0'; |
314 | file_header->name = concat_path_file(tar.prefix, tar.name); |
315 | } else |
316 | file_header->name = xstrdup(tar.name); |
317 | } |
318 | |
319 | /* Set bits 12-15 of the files mode */ |
320 | /* (typeflag was not trashed because chksum does not use getOctal) */ |
321 | switch (tar.typeflag) { |
322 | /* busybox identifies hard links as being regular files with 0 size and a link name */ |
323 | case '1': |
324 | file_header->mode |= S_IFREG; |
325 | break; |
326 | case '7': |
327 | /* case 0: */ |
328 | case '0': |
329 | #if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY |
330 | if (last_char_is(file_header->name, '/')) { |
331 | goto set_dir; |
332 | } |
333 | #endif |
334 | file_header->mode |= S_IFREG; |
335 | break; |
336 | case '2': |
337 | file_header->mode |= S_IFLNK; |
338 | /* have seen tarballs with size field containing |
339 | * the size of the link target's name */ |
340 | size0: |
341 | file_header->size = 0; |
342 | break; |
343 | case '3': |
344 | file_header->mode |= S_IFCHR; |
345 | goto size0; /* paranoia */ |
346 | case '4': |
347 | file_header->mode |= S_IFBLK; |
348 | goto size0; |
349 | case '5': |
350 | IF_FEATURE_TAR_OLDGNU_COMPATIBILITY(set_dir:) |
351 | file_header->mode |= S_IFDIR; |
352 | goto size0; |
353 | case '6': |
354 | file_header->mode |= S_IFIFO; |
355 | goto size0; |
356 | #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS |
357 | case 'L': |
358 | /* free: paranoia: tar with several consecutive longnames */ |
359 | free(p_longname); |
360 | /* For paranoia reasons we allocate extra NUL char */ |
361 | p_longname = xzalloc(file_header->size + 1); |
362 | /* We read ASCIZ string, including NUL */ |
363 | xread(archive_handle->src_fd, p_longname, file_header->size); |
364 | archive_handle->offset += file_header->size; |
365 | /* return get_header_tar(archive_handle); */ |
366 | /* gcc 4.1.1 didn't optimize it into jump */ |
367 | /* so we will do it ourself, this also saves stack */ |
368 | goto again; |
369 | case 'K': |
370 | free(p_linkname); |
371 | p_linkname = xzalloc(file_header->size + 1); |
372 | xread(archive_handle->src_fd, p_linkname, file_header->size); |
373 | archive_handle->offset += file_header->size; |
374 | /* return get_header_tar(archive_handle); */ |
375 | goto again; |
376 | case 'D': /* GNU dump dir */ |
377 | case 'M': /* Continuation of multi volume archive */ |
378 | case 'N': /* Old GNU for names > 100 characters */ |
379 | case 'S': /* Sparse file */ |
380 | case 'V': /* Volume header */ |
381 | #endif |
382 | #if !ENABLE_FEATURE_TAR_SELINUX |
383 | case 'g': /* pax global header */ |
384 | case 'x': /* pax extended header */ |
385 | #else |
386 | skip_ext_hdr: |
387 | #endif |
388 | { |
389 | off_t sz; |
390 | bb_error_msg("warning: skipping header '%c'", tar.typeflag); |
391 | sz = (file_header->size + 511) & ~(off_t)511; |
392 | archive_handle->offset += sz; |
393 | sz >>= 9; /* sz /= 512 but w/o contortions for signed div */ |
394 | while (sz--) |
395 | xread(archive_handle->src_fd, &tar, 512); |
396 | /* return get_header_tar(archive_handle); */ |
397 | goto again_after_align; |
398 | } |
399 | #if ENABLE_FEATURE_TAR_SELINUX |
400 | case 'g': /* pax global header */ |
401 | case 'x': { /* pax extended header */ |
402 | char **pp; |
403 | if ((uoff_t)file_header->size > 0xfffff) /* paranoia */ |
404 | goto skip_ext_hdr; |
405 | pp = (tar.typeflag == 'g') ? &archive_handle->tar__global_sctx : &archive_handle->tar__next_file_sctx; |
406 | free(*pp); |
407 | *pp = get_selinux_sctx_from_pax_hdr(archive_handle, file_header->size); |
408 | goto again; |
409 | } |
410 | #endif |
411 | default: |
412 | bb_error_msg_and_die("unknown typeflag: 0x%x", tar.typeflag); |
413 | } |
414 | |
415 | #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS |
416 | if (p_longname) { |
417 | file_header->name = p_longname; |
418 | p_longname = NULL; |
419 | } |
420 | if (p_linkname) { |
421 | file_header->link_target = p_linkname; |
422 | p_linkname = NULL; |
423 | } |
424 | #endif |
425 | if (strncmp(file_header->name, "/../"+1, 3) == 0 |
426 | || strstr(file_header->name, "/../") |
427 | ) { |
428 | bb_error_msg_and_die("name with '..' encountered: '%s'", |
429 | file_header->name); |
430 | } |
431 | |
432 | /* Strip trailing '/' in directories */ |
433 | /* Must be done after mode is set as '/' is used to check if it's a directory */ |
434 | cp = last_char_is(file_header->name, '/'); |
435 | |
436 | if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) { |
437 | archive_handle->action_header(/*archive_handle->*/ file_header); |
438 | /* Note that we kill the '/' only after action_header() */ |
439 | /* (like GNU tar 1.15.1: verbose mode outputs "dir/dir/") */ |
440 | if (cp) |
441 | *cp = '\0'; |
442 | archive_handle->action_data(archive_handle); |
443 | if (archive_handle->accept || archive_handle->reject) |
444 | llist_add_to(&archive_handle->passed, file_header->name); |
445 | else /* Caller isn't interested in list of unpacked files */ |
446 | free(file_header->name); |
447 | } else { |
448 | data_skip(archive_handle); |
449 | free(file_header->name); |
450 | } |
451 | archive_handle->offset += file_header->size; |
452 | |
453 | free(file_header->link_target); |
454 | /* Do not free(file_header->name)! |
455 | * It might be inserted in archive_handle->passed - see above */ |
456 | #if ENABLE_FEATURE_TAR_UNAME_GNAME |
457 | free(file_header->tar__uname); |
458 | free(file_header->tar__gname); |
459 | #endif |
460 | return EXIT_SUCCESS; |
461 | } |