source: MondoRescue/branches/2.2.9/mindi-busybox/archival/libarchive/get_header_tar.c@ 2725

Last change on this file since 2725 was 2725, checked in by Bruno Cornec, 13 years ago
  • Update mindi-busybox to 1.18.3 to avoid problems with the tar command which is now failing on recent versions with busybox 1.7.3
  • Property svn:eol-style set to native
File size: 13.9 KB
Line 
1/* vi: set sw=4 ts=4: */
2/* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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 "archive.h"
16
17typedef uint32_t aliased_uint32_t FIX_ALIASING;
18typedef off_t aliased_off_t FIX_ALIASING;
19
20
21/* NB: _DESTROYS_ str[len] character! */
22static 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"
69static 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
121char 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}
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