archival/libunarchive/get_header_tar.c

/* vi: set sw=4 ts=4: */
/* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 *
 *  FIXME:
 *    In privileged mode if uname and gname map to a uid and gid then use the
 *    mapped value instead of the uid/gid values in tar header
 *
 *  References:
 *    GNU tar and star man pages,
 *    Opengroup's ustar interchange format,
 *	http://www.opengroup.org/onlinepubs/007904975/utilities/pax.html
 */

#include "libbb.h"
#include "unarchive.h"

#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
static char *longname;
static char *linkname;
#else
enum {
	longname = 0,
	linkname = 0,
};
#endif

/* NB: _DESTROYS_ str[len] character! */
static unsigned long long getOctal(char *str, int len)
{
	unsigned long long v;
	/* Actually, tar header allows leading spaces also.
	 * Oh well, we will be liberal and skip this...
	 * The only downside probably is that we allow "-123" too :)
	if (*str < '0' || *str > '7')
		bb_error_msg_and_die("corrupted octal value in tar header");
	*/
	str[len] = '\0';
	v = strtoull(str, &str, 8);
	if (*str)
		bb_error_msg_and_die("corrupted octal value in tar header");
	return v;
}
#define GET_OCTAL(a) getOctal((a), sizeof(a))

void BUG_tar_header_size(void);
char get_header_tar(archive_handle_t *archive_handle)
{
	static int end;

	file_header_t *file_header = archive_handle->file_header;
	struct {
		/* ustar header, Posix 1003.1 */
		char name[100];     /*   0-99 */
		char mode[8];       /* 100-107 */
		char uid[8];        /* 108-115 */
		char gid[8];        /* 116-123 */
		char size[12];      /* 124-135 */
		char mtime[12];     /* 136-147 */
		char chksum[8];     /* 148-155 */
		char typeflag;      /* 156-156 */
		char linkname[100]; /* 157-256 */
		char magic[6];      /* 257-262 */
		char version[2];    /* 263-264 */
		char uname[32];     /* 265-296 */
		char gname[32];     /* 297-328 */
		char devmajor[8];   /* 329-336 */
		char devminor[8];   /* 337-344 */
		char prefix[155];   /* 345-499 */
		char padding[12];   /* 500-512 */
	} tar;
	char *cp;
	int sum, i;
	int parse_names;

	if (sizeof(tar) != 512)
		BUG_tar_header_size();

#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
 again:
#endif
	/* Align header */
	data_align(archive_handle, 512);

 again_after_align:

	xread(archive_handle->src_fd, &tar, 512);
	archive_handle->offset += 512;

	/* If there is no filename its an empty header */
	if (tar.name[0] == 0) {
		if (end) {
			/* This is the second consecutive empty header! End of archive!
			 * Read until the end to empty the pipe from gz or bz2
			 */
			while (full_read(archive_handle->src_fd, &tar, 512) == 512)
				/* repeat */;
			return EXIT_FAILURE;
		}
		end = 1;
		return EXIT_SUCCESS;
	}
	end = 0;

	/* Check header has valid magic, "ustar" is for the proper tar
	 * 0's are for the old tar format
	 */
	if (strncmp(tar.magic, "ustar", 5) != 0) {
#if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
		if (memcmp(tar.magic, "\0\0\0\0", 5) != 0)
#endif
			bb_error_msg_and_die("invalid tar magic");
	}
	/* Do checksum on headers */
	sum = ' ' * sizeof(tar.chksum);
	for (i = 0; i < 148 ; i++) {
		sum += ((char*)&tar)[i];
	}
	for (i = 156; i < 512 ; i++) {
		sum += ((char*)&tar)[i];
	}
	/* This field does not need special treatment (getOctal) */
	if (sum != xstrtoul(tar.chksum, 8)) {
		bb_error_msg_and_die("invalid tar header checksum");
	}

	/* 0 is reserved for high perf file, treat as normal file */
	if (!tar.typeflag) tar.typeflag = '0';
	parse_names = (tar.typeflag >= '0' && tar.typeflag <= '7');

	/* getOctal trashes subsequent field, therefore we call it
	 * on fields in reverse order */
	if (tar.devmajor[0]) {
		unsigned minor = GET_OCTAL(tar.devminor);
		unsigned major = GET_OCTAL(tar.devmajor);
		file_header->device = makedev(major, minor);
	}
	file_header->link_name = NULL;
	if (!linkname && parse_names && tar.linkname[0]) {
		/* we trash magic[0] here, it's ok */
		tar.linkname[sizeof(tar.linkname)] = '\0';
		file_header->link_name = xstrdup(tar.linkname);
		/* FIXME: what if we have non-link object with link_name? */
		/* Will link_name be free()ed? */
	}
	file_header->mtime = GET_OCTAL(tar.mtime);
	file_header->size = GET_OCTAL(tar.size);
	file_header->gid = GET_OCTAL(tar.gid);
	file_header->uid = GET_OCTAL(tar.uid);
	/* Set bits 0-11 of the files mode */
	file_header->mode = 07777 & GET_OCTAL(tar.mode);

	file_header->name = NULL;
	if (!longname && parse_names) {
		/* we trash mode[0] here, it's ok */
		tar.name[sizeof(tar.name)] = '\0';
		if (tar.prefix[0]) {
			/* and padding[0] */
			tar.prefix[sizeof(tar.prefix)] = '\0';
			file_header->name = concat_path_file(tar.prefix, tar.name);
		} else
			file_header->name = xstrdup(tar.name);
	}

	/* Set bits 12-15 of the files mode */
	/* (typeflag was not trashed because chksum does not use getOctal) */
	switch (tar.typeflag) {
	/* busybox identifies hard links as being regular files with 0 size and a link name */
	case '1':
		file_header->mode |= S_IFREG;
		break;
	case '7':
	/* case 0: */
	case '0':
#if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
		if (last_char_is(file_header->name, '/')) {
			file_header->mode |= S_IFDIR;
		} else
#endif
		file_header->mode |= S_IFREG;
		break;
	case '2':
		file_header->mode |= S_IFLNK;
		break;
	case '3':
		file_header->mode |= S_IFCHR;
		break;
	case '4':
		file_header->mode |= S_IFBLK;
		break;
	case '5':
		file_header->mode |= S_IFDIR;
		break;
	case '6':
		file_header->mode |= S_IFIFO;
		break;
#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
	case 'L':
		/* free: paranoia: tar with several consecutive longnames */
		free(longname);
		/* For paranoia reasons we allocate extra NUL char */
		longname = xzalloc(file_header->size + 1);
		/* We read ASCIZ string, including NUL */
		xread(archive_handle->src_fd, longname, file_header->size);
		archive_handle->offset += file_header->size;
		/* return get_header_tar(archive_handle); */
		/* gcc 4.1.1 didn't optimize it into jump */
		/* so we will do it ourself, this also saves stack */
		goto again;
	case 'K':
		free(linkname);
		linkname = xzalloc(file_header->size + 1);
		xread(archive_handle->src_fd, linkname, file_header->size);
		archive_handle->offset += file_header->size;
		/* return get_header_tar(archive_handle); */
		goto again;
	case 'D':	/* GNU dump dir */
	case 'M':	/* Continuation of multi volume archive */
	case 'N':	/* Old GNU for names > 100 characters */
	case 'S':	/* Sparse file */
	case 'V':	/* Volume header */
#endif
	case 'g':	/* pax global header */
	case 'x': {	/* pax extended header */
		off_t sz;
		bb_error_msg("warning: skipping header '%c'", tar.typeflag);
		sz = (file_header->size + 511) & ~(off_t)511;
		archive_handle->offset += sz;
		sz >>= 9; /* sz /= 512 but w/o contortions for signed div */
		while (sz--)
			xread(archive_handle->src_fd, &tar, 512);
		/* return get_header_tar(archive_handle); */
		goto again_after_align;
	}
	default:
		bb_error_msg_and_die("unknown typeflag: 0x%x", tar.typeflag);
	}

#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
	if (longname) {
		file_header->name = longname;
		longname = NULL;
	}
	if (linkname) {
		file_header->link_name = linkname;
		linkname = NULL;
	}
#endif
	if (!strncmp(file_header->name, "/../"+1, 3)
	 || strstr(file_header->name, "/../")
	) {
		bb_error_msg_and_die("name with '..' encountered: '%s'",
				file_header->name);
	}

	/* Strip trailing '/' in directories */
	/* Must be done after mode is set as '/' is used to check if it's a directory */
	cp = last_char_is(file_header->name, '/');

	if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) {
		archive_handle->action_header(archive_handle->file_header);
		/* Note that we kill the '/' only after action_header() */
		/* (like GNU tar 1.15.1: verbose mode outputs "dir/dir/") */
		if (cp) *cp = '\0';
		archive_handle->flags |= ARCHIVE_EXTRACT_QUIET;
		archive_handle->action_data(archive_handle);
		llist_add_to(&(archive_handle->passed), file_header->name);
	} else {
		data_skip(archive_handle);
		free(file_header->name);
	}
	archive_handle->offset += file_header->size;

	free(file_header->link_name);
	/* Do not free(file_header->name)! */

	return EXIT_SUCCESS;
}
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	#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
18	static char *longname;
19	static char *linkname;
20	#else
21	enum {
22	longname = 0,
23	linkname = 0,
24	};
25	#endif
26
27	/* NB: _DESTROYS_ str[len] character! */
28	static unsigned long long getOctal(char *str, int len)
29	{
30	unsigned long long v;
31	/* Actually, tar header allows leading spaces also.
32	* Oh well, we will be liberal and skip this...
33	* The only downside probably is that we allow "-123" too :)
34	if (str < '0' \|\| str > '7')
35	bb_error_msg_and_die("corrupted octal value in tar header");
36	*/
37	str[len] = '\0';
38	v = strtoull(str, &str, 8);
39	if (*str)
40	bb_error_msg_and_die("corrupted octal value in tar header");
41	return v;
42	}
43	#define GET_OCTAL(a) getOctal((a), sizeof(a))
44
45	void BUG_tar_header_size(void);
46	char get_header_tar(archive_handle_t *archive_handle)
47	{
48	static int end;
49
50	file_header_t *file_header = archive_handle->file_header;
51	struct {
52	/* ustar header, Posix 1003.1 */
53	char name[100]; /* 0-99 */
54	char mode[8]; /* 100-107 */
55	char uid[8]; /* 108-115 */
56	char gid[8]; /* 116-123 */
57	char size[12]; /* 124-135 */
58	char mtime[12]; /* 136-147 */
59	char chksum[8]; /* 148-155 */
60	char typeflag; /* 156-156 */
61	char linkname[100]; /* 157-256 */
62	char magic[6]; /* 257-262 */
63	char version[2]; /* 263-264 */
64	char uname[32]; /* 265-296 */
65	char gname[32]; /* 297-328 */
66	char devmajor[8]; /* 329-336 */
67	char devminor[8]; /* 337-344 */
68	char prefix[155]; /* 345-499 */
69	char padding[12]; /* 500-512 */
70	} tar;
71	char *cp;
72	int sum, i;
73	int parse_names;
74
75	if (sizeof(tar) != 512)
76	BUG_tar_header_size();
77
78	#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
79	again:
80	#endif
81	/* Align header */
82	data_align(archive_handle, 512);
83
84	again_after_align:
85
86	xread(archive_handle->src_fd, &tar, 512);
87	archive_handle->offset += 512;
88
89	/* If there is no filename its an empty header */
90	if (tar.name[0] == 0) {
91	if (end) {
92	/* This is the second consecutive empty header! End of archive!
93	* Read until the end to empty the pipe from gz or bz2
94	*/
95	while (full_read(archive_handle->src_fd, &tar, 512) == 512)
96	/* repeat */;
97	return EXIT_FAILURE;
98	}
99	end = 1;
100	return EXIT_SUCCESS;
101	}
102	end = 0;
103
104	/* Check header has valid magic, "ustar" is for the proper tar
105	* 0's are for the old tar format
106	*/
107	if (strncmp(tar.magic, "ustar", 5) != 0) {
108	#if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
109	if (memcmp(tar.magic, "\0\0\0\0", 5) != 0)
110	#endif
111	bb_error_msg_and_die("invalid tar magic");
112	}
113	/* Do checksum on headers */
114	sum = ' ' * sizeof(tar.chksum);
115	for (i = 0; i < 148 ; i++) {
116	sum += ((char*)&tar)[i];
117	}
118	for (i = 156; i < 512 ; i++) {
119	sum += ((char*)&tar)[i];
120	}
121	/* This field does not need special treatment (getOctal) */
122	if (sum != xstrtoul(tar.chksum, 8)) {
123	bb_error_msg_and_die("invalid tar header checksum");
124	}
125
126	/* 0 is reserved for high perf file, treat as normal file */
127	if (!tar.typeflag) tar.typeflag = '0';
128	parse_names = (tar.typeflag >= '0' && tar.typeflag <= '7');
129
130	/* getOctal trashes subsequent field, therefore we call it
131	* on fields in reverse order */
132	if (tar.devmajor[0]) {
133	unsigned minor = GET_OCTAL(tar.devminor);
134	unsigned major = GET_OCTAL(tar.devmajor);
135	file_header->device = makedev(major, minor);
136	}
137	file_header->link_name = NULL;
138	if (!linkname && parse_names && tar.linkname[0]) {
139	/* we trash magic[0] here, it's ok */
140	tar.linkname[sizeof(tar.linkname)] = '\0';
141	file_header->link_name = xstrdup(tar.linkname);
142	/* FIXME: what if we have non-link object with link_name? */
143	/* Will link_name be free()ed? */
144	}
145	file_header->mtime = GET_OCTAL(tar.mtime);
146	file_header->size = GET_OCTAL(tar.size);
147	file_header->gid = GET_OCTAL(tar.gid);
148	file_header->uid = GET_OCTAL(tar.uid);
149	/* Set bits 0-11 of the files mode */
150	file_header->mode = 07777 & GET_OCTAL(tar.mode);
151
152	file_header->name = NULL;
153	if (!longname && parse_names) {
154	/* we trash mode[0] here, it's ok */
155	tar.name[sizeof(tar.name)] = '\0';
156	if (tar.prefix[0]) {
157	/* and padding[0] */
158	tar.prefix[sizeof(tar.prefix)] = '\0';
159	file_header->name = concat_path_file(tar.prefix, tar.name);
160	} else
161	file_header->name = xstrdup(tar.name);
162	}
163
164	/* Set bits 12-15 of the files mode */
165	/* (typeflag was not trashed because chksum does not use getOctal) */
166	switch (tar.typeflag) {
167	/* busybox identifies hard links as being regular files with 0 size and a link name */
168	case '1':
169	file_header->mode \|= S_IFREG;
170	break;
171	case '7':
172	/* case 0: */
173	case '0':
174	#if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
175	if (last_char_is(file_header->name, '/')) {
176	file_header->mode \|= S_IFDIR;
177	} else
178	#endif
179	file_header->mode \|= S_IFREG;
180	break;
181	case '2':
182	file_header->mode \|= S_IFLNK;
183	break;
184	case '3':
185	file_header->mode \|= S_IFCHR;
186	break;
187	case '4':
188	file_header->mode \|= S_IFBLK;
189	break;
190	case '5':
191	file_header->mode \|= S_IFDIR;
192	break;
193	case '6':
194	file_header->mode \|= S_IFIFO;
195	break;
196	#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
197	case 'L':
198	/* free: paranoia: tar with several consecutive longnames */
199	free(longname);
200	/* For paranoia reasons we allocate extra NUL char */
201	longname = xzalloc(file_header->size + 1);
202	/* We read ASCIZ string, including NUL */
203	xread(archive_handle->src_fd, longname, file_header->size);
204	archive_handle->offset += file_header->size;
205	/* return get_header_tar(archive_handle); */
206	/* gcc 4.1.1 didn't optimize it into jump */
207	/* so we will do it ourself, this also saves stack */
208	goto again;
209	case 'K':
210	free(linkname);
211	linkname = xzalloc(file_header->size + 1);
212	xread(archive_handle->src_fd, linkname, file_header->size);
213	archive_handle->offset += file_header->size;
214	/* return get_header_tar(archive_handle); */
215	goto again;
216	case 'D': /* GNU dump dir */
217	case 'M': /* Continuation of multi volume archive */
218	case 'N': /* Old GNU for names > 100 characters */
219	case 'S': /* Sparse file */
220	case 'V': /* Volume header */
221	#endif
222	case 'g': /* pax global header */
223	case 'x': { /* pax extended header */
224	off_t sz;
225	bb_error_msg("warning: skipping header '%c'", tar.typeflag);
226	sz = (file_header->size + 511) & ~(off_t)511;
227	archive_handle->offset += sz;
228	sz >>= 9; /* sz /= 512 but w/o contortions for signed div */
229	while (sz--)
230	xread(archive_handle->src_fd, &tar, 512);
231	/* return get_header_tar(archive_handle); */
232	goto again_after_align;
233	}
234	default:
235	bb_error_msg_and_die("unknown typeflag: 0x%x", tar.typeflag);
236	}
237
238	#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
239	if (longname) {
240	file_header->name = longname;
241	longname = NULL;
242	}
243	if (linkname) {
244	file_header->link_name = linkname;
245	linkname = NULL;
246	}
247	#endif
248	if (!strncmp(file_header->name, "/../"+1, 3)
249	\|\| strstr(file_header->name, "/../")
250	) {
251	bb_error_msg_and_die("name with '..' encountered: '%s'",
252	file_header->name);
253	}
254
255	/* Strip trailing '/' in directories */
256	/* Must be done after mode is set as '/' is used to check if it's a directory */
257	cp = last_char_is(file_header->name, '/');
258
259	if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) {
260	archive_handle->action_header(archive_handle->file_header);
261	/* Note that we kill the '/' only after action_header() */
262	/* (like GNU tar 1.15.1: verbose mode outputs "dir/dir/") */
263	if (cp) *cp = '\0';
264	archive_handle->flags \|= ARCHIVE_EXTRACT_QUIET;
265	archive_handle->action_data(archive_handle);
266	llist_add_to(&(archive_handle->passed), file_header->name);
267	} else {
268	data_skip(archive_handle);
269	free(file_header->name);
270	}
271	archive_handle->offset += file_header->size;
272
273	free(file_header->link_name);
274	/* Do not free(file_header->name)! */
275
276	return EXIT_SUCCESS;
277	}