busybox/archival/libunarchive/get_header_tar.c

369 lines
11 KiB
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 && (!ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY || *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 smallint end;
#if ENABLE_FEATURE_TAR_AUTODETECT
static smallint not_first;
#endif
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 */
/* POSIX: "ustar" NUL "00" */
/* GNU tar: "ustar " NUL */
/* Normally it's defined as magic[6] followed by
* version[2], but we put them together to save code.
*/
char magic[8]; /* 257-264 */
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 i, sum_u, sum;
#if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
int sum_s;
#endif
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:
#if ENABLE_DESKTOP
i = full_read(archive_handle->src_fd, &tar, 512);
/* if GNU tar sees EOF in above read, it says:
* "tar: A lone zero block at N", where N = kilobyte
* where EOF was met (not EOF block, actual EOF!),
* and tar will exit with error code 0.
* We will mimic exit(0), although we will not mimic
* the message and we don't check whether we indeed
* saw zero block directly before this. */
if (i == 0)
xfunc_error_retval = 0;
if (i != 512)
bb_error_msg_and_die("short read");
#else
xread(archive_handle->src_fd, &tar, 512);
#endif
archive_handle->offset += 512;
/* If there is no filename its an empty header */
if (tar.name[0] == 0 && tar.prefix[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)
continue;
return EXIT_FAILURE;
}
end = 1;
return EXIT_SUCCESS;
}
end = 0;
/* Check header has valid magic, "ustar" is for the proper tar,
* five NULs are for the old tar format */
if (strncmp(tar.magic, "ustar", 5) != 0
&& (!ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
|| memcmp(tar.magic, "\0\0\0\0", 5) != 0)
) {
#if ENABLE_FEATURE_TAR_AUTODETECT
char (*get_header_ptr)(archive_handle_t *);
/* tar gz/bz autodetect: check for gz/bz2 magic.
* If it is the very first block, and we see the magic,
* we can switch to get_header_tar_gz/bz2/lzma().
* Needs seekable fd. I wish recv(MSG_PEEK) would work
* on any fd... */
if (not_first)
goto err;
#if ENABLE_FEATURE_TAR_GZIP
if (tar.name[0] == 0x1f && tar.name[1] == 0x8b) { /* gzip */
get_header_ptr = get_header_tar_gz;
} else
#endif
#if ENABLE_FEATURE_TAR_BZIP2
if (tar.name[0] == 'B' && tar.name[1] == 'Z'
&& tar.name[2] == 'h' && isdigit(tar.name[3])
) { /* bzip2 */
get_header_ptr = get_header_tar_bz2;
} else
#endif
goto err;
if (lseek(archive_handle->src_fd, -512, SEEK_CUR) != 0)
goto err;
while (get_header_ptr(archive_handle) == EXIT_SUCCESS)
continue;
return EXIT_FAILURE;
err:
#endif /* FEATURE_TAR_AUTODETECT */
bb_error_msg_and_die("invalid tar magic");
}
#if ENABLE_FEATURE_TAR_AUTODETECT
not_first = 1;
#endif
/* Do checksum on headers.
* POSIX says that checksum is done on unsigned bytes, but
* Sun and HP-UX gets it wrong... more details in
* GNU tar source. */
#if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
sum_s = ' ' * sizeof(tar.chksum);
#endif
sum_u = ' ' * sizeof(tar.chksum);
for (i = 0; i < 148; i++) {
sum_u += ((unsigned char*)&tar)[i];
#if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
sum_s += ((signed char*)&tar)[i];
#endif
}
for (i = 156; i < 512; i++) {
sum_u += ((unsigned char*)&tar)[i];
#if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
sum_s += ((signed char*)&tar)[i];
#endif
}
#if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
sum = strtoul(tar.chksum, &cp, 8);
if ((*cp && *cp != ' ')
|| (sum_u != sum USE_FEATURE_TAR_OLDSUN_COMPATIBILITY(&& sum_s != sum))
) {
bb_error_msg_and_die("invalid tar header checksum");
}
#else
/* This field does not need special treatment (getOctal) */
sum = xstrtoul(tar.chksum, 8);
if (sum_u != sum USE_FEATURE_TAR_OLDSUN_COMPATIBILITY(&& sum_s != sum)) {
bb_error_msg_and_die("invalid tar header checksum");
}
#endif
/* 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]) {
char t = tar.prefix[0];
/* we trash prefix[0] here, but we DO need it later! */
unsigned minor = GET_OCTAL(tar.devminor);
unsigned major = GET_OCTAL(tar.devmajor);
file_header->device = makedev(major, minor);
tar.prefix[0] = t;
}
file_header->link_target = NULL;
if (!linkname && parse_names && tar.linkname[0]) {
file_header->link_target = xstrndup(tar.linkname, sizeof(tar.linkname));
/* FIXME: what if we have non-link object with link_target? */
/* Will link_target be free()ed? */
}
#if ENABLE_FEATURE_TAR_UNAME_GNAME
file_header->uname = tar.uname[0] ? xstrndup(tar.uname, sizeof(tar.uname)) : NULL;
file_header->gname = tar.gname[0] ? xstrndup(tar.gname, sizeof(tar.gname)) : NULL;
#endif
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'; - gcc 4.3.0 would complain
tar.mode[0] = '\0';
if (tar.prefix[0]) {
/* and padding[0] */
//tar.prefix[sizeof(tar.prefix)] = '\0'; - gcc 4.3.0 would complain
tar.padding[0] = '\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_target = 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_target);
/* Do not free(file_header->name)! */
#if ENABLE_FEATURE_TAR_UNAME_GNAME
free(file_header->uname);
free(file_header->gname);
#endif
return EXIT_SUCCESS;
}