492 lines
16 KiB
C
492 lines
16 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*
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* FIXME:
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* In privileged mode if uname and gname map to a uid and gid then use the
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* mapped value instead of the uid/gid values in tar header
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*
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* References:
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* GNU tar and star man pages,
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* Opengroup's ustar interchange format,
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* http://www.opengroup.org/onlinepubs/007904975/utilities/pax.html
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*/
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#include "libbb.h"
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#include "bb_archive.h"
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typedef uint32_t aliased_uint32_t FIX_ALIASING;
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typedef off_t aliased_off_t FIX_ALIASING;
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/* NB: _DESTROYS_ str[len] character! */
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static unsigned long long getOctal(char *str, int len)
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{
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unsigned long long v;
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char *end;
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/* NB: leading spaces are allowed. Using strtoull to handle that.
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* The downside is that we accept e.g. "-123" too :(
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*/
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str[len] = '\0';
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v = strtoull(str, &end, 8);
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/* std: "Each numeric field is terminated by one or more
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* <space> or NUL characters". We must support ' '! */
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if (*end != '\0' && *end != ' ') {
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int8_t first = str[0];
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if (!(first & 0x80))
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bb_simple_error_msg_and_die("corrupted octal value in tar header");
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/*
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* GNU tar uses "base-256 encoding" for very large numbers.
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* Encoding is binary, with highest bit always set as a marker
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* and sign in next-highest bit:
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* 80 00 .. 00 - zero
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* bf ff .. ff - largest positive number
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* ff ff .. ff - minus 1
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* c0 00 .. 00 - smallest negative number
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*
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* Example of tar file with 8914993153 (0x213600001) byte file.
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* Field starts at offset 7c:
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* 00070 30 30 30 00 30 30 30 30 30 30 30 00 80 00 00 00 |000.0000000.....|
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* 00080 00 00 00 02 13 60 00 01 31 31 31 32 30 33 33 36 |.....`..11120336|
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*
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* NB: tarballs with NEGATIVE unix times encoded that way were seen!
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*/
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/* Sign-extend 7bit 'first' to 64bit 'v' (that is, using 6th bit as sign): */
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first <<= 1;
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first >>= 1; /* now 7th bit = 6th bit */
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v = first; /* sign-extend 8 bits to 64 */
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while (--len != 0)
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v = (v << 8) + (uint8_t) *++str;
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}
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return v;
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}
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#define GET_OCTAL(a) getOctal((a), sizeof(a))
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#define TAR_EXTD (ENABLE_FEATURE_TAR_GNU_EXTENSIONS || ENABLE_FEATURE_TAR_SELINUX)
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#if !TAR_EXTD
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#define process_pax_hdr(archive_handle, sz, global) \
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process_pax_hdr(archive_handle, sz)
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#endif
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/* "global" is 0 or 1 */
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static void process_pax_hdr(archive_handle_t *archive_handle, unsigned sz, int global)
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{
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#if !TAR_EXTD
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unsigned blk_sz = (sz + 511) & (~511);
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seek_by_read(archive_handle->src_fd, blk_sz);
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#else
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unsigned blk_sz = (sz + 511) & (~511);
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char *buf, *p;
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p = buf = xmalloc(blk_sz + 1);
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xread(archive_handle->src_fd, buf, blk_sz);
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archive_handle->offset += blk_sz;
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/* prevent bb_strtou from running off the buffer */
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buf[sz] = '\0';
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while (sz != 0) {
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char *end, *value;
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unsigned len;
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/* Every record has this format: "LEN NAME=VALUE\n" */
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len = bb_strtou(p, &end, 10);
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/* expect errno to be EINVAL, because the character
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* following the digits should be a space
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*/
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p += len;
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sz -= len;
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if (
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/** (int)sz < 0 - not good enough for huge malicious VALUE of 2^32-1 */
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(int)(sz|len) < 0 /* this works */
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|| len == 0
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|| errno != EINVAL
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|| *end != ' '
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) {
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bb_simple_error_msg("malformed extended header, skipped");
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// More verbose version:
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//bb_error_msg("malformed extended header at %"OFF_FMT"d, skipped",
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// archive_handle->offset - (sz + len));
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break;
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}
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/* overwrite the terminating newline with NUL
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* (we do not bother to check that it *was* a newline)
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*/
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p[-1] = '\0';
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value = end + 1;
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# if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
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if (!global) {
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if (is_prefixed_with(value, "path=")) {
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value += sizeof("path=") - 1;
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free(archive_handle->tar__longname);
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archive_handle->tar__longname = xstrdup(value);
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continue;
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}
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if (is_prefixed_with(value, "linkpath=")) {
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value += sizeof("linkpath=") - 1;
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free(archive_handle->tar__linkname);
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archive_handle->tar__linkname = xstrdup(value);
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continue;
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}
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}
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# endif
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# if ENABLE_FEATURE_TAR_SELINUX
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/* Scan for SELinux contexts, via "RHT.security.selinux" keyword.
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* This is what Red Hat's patched version of tar uses.
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*/
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# define SELINUX_CONTEXT_KEYWORD "RHT.security.selinux"
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if (is_prefixed_with(value, SELINUX_CONTEXT_KEYWORD"=")) {
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value += sizeof(SELINUX_CONTEXT_KEYWORD"=") - 1;
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free(archive_handle->tar__sctx[global]);
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archive_handle->tar__sctx[global] = xstrdup(value);
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continue;
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}
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# endif
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}
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free(buf);
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#endif
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}
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#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
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static void die_if_bad_fnamesize(off_t sz)
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{
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if ((uoff_t)sz > 0xfff) /* more than 4k?! no funny business please */
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bb_simple_error_msg_and_die("bad archive");
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}
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#endif
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char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
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{
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file_header_t *file_header = archive_handle->file_header;
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struct tar_header_t tar;
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char *cp;
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int tar_typeflag; /* can be "char", "int" seems give smaller code */
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int i, sum_u, sum;
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#if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
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int sum_s;
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#endif
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int parse_names;
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/* Our "private data" */
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#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
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# define p_longname (archive_handle->tar__longname)
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# define p_linkname (archive_handle->tar__linkname)
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#else
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# define p_longname 0
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# define p_linkname 0
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#endif
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#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS || ENABLE_FEATURE_TAR_SELINUX
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again:
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#endif
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/* Align header */
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data_align(archive_handle, 512);
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again_after_align:
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#if ENABLE_DESKTOP || ENABLE_FEATURE_TAR_AUTODETECT
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/* to prevent misdetection of bz2 sig */
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*(aliased_uint32_t*)&tar = 0;
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i = full_read(archive_handle->src_fd, &tar, 512);
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/* If GNU tar sees EOF in above read, it says:
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* "tar: A lone zero block at N", where N = kilobyte
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* where EOF was met (not EOF block, actual EOF!),
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* and exits with EXIT_SUCCESS.
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* We will mimic exit(EXIT_SUCCESS), although we will not mimic
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* the message and we don't check whether we indeed
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* saw zero block directly before this. */
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if (i == 0) {
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/* GNU tar 1.29 will be silent if tar archive ends abruptly
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* (if there are no zero blocks at all, and last read returns zero,
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* not short read 0 < len < 512). Complain only if
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* the very first read fails. Grrr.
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*/
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if (archive_handle->offset == 0)
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bb_simple_error_msg("short read");
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/* this merely signals end of archive, not exit(1): */
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return EXIT_FAILURE;
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}
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if (i != 512) {
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IF_FEATURE_TAR_AUTODETECT(goto autodetect;)
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bb_simple_error_msg_and_die("short read");
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}
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#else
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i = 512;
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xread(archive_handle->src_fd, &tar, i);
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#endif
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archive_handle->offset += i;
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/* If there is no filename its an empty header */
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if (tar.name[0] == 0 && tar.prefix[0] == 0
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/* Have seen a tar archive with pax 'x' header supplying UTF8 filename,
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* with actual file having all name fields NUL-filled. Check this: */
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&& !p_longname
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) {
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if (archive_handle->tar__end) {
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/* Second consecutive empty header - end of archive.
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* Read until the end to empty the pipe from gz or bz2
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*/
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while (full_read(archive_handle->src_fd, &tar, 512) == 512)
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continue;
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return EXIT_FAILURE; /* "end of archive" */
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}
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archive_handle->tar__end = 1;
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return EXIT_SUCCESS; /* "decoded one header" */
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}
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archive_handle->tar__end = 0;
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/* Check header has valid magic, "ustar" is for the proper tar,
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* five NULs are for the old tar format */
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if (!is_prefixed_with(tar.magic, "ustar")
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&& (!ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
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|| memcmp(tar.magic, "\0\0\0\0", 5) != 0)
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) {
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#if ENABLE_FEATURE_TAR_AUTODETECT
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autodetect:
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/* Two different causes for lseek() != 0:
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* unseekable fd (would like to support that too, but...),
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* or not first block (false positive, it's not .gz/.bz2!) */
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if (lseek(archive_handle->src_fd, -i, SEEK_CUR) != 0)
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goto err;
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if (setup_unzip_on_fd(archive_handle->src_fd, /*fail_if_not_compressed:*/ 0) != 0)
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err:
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bb_simple_error_msg_and_die("invalid tar magic");
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archive_handle->offset = 0;
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goto again_after_align;
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#endif
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bb_simple_error_msg_and_die("invalid tar magic");
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}
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/* Do checksum on headers.
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* POSIX says that checksum is done on unsigned bytes, but
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* Sun and HP-UX gets it wrong... more details in
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* GNU tar source. */
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sum_u = ' ' * sizeof(tar.chksum);
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#if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
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sum_s = sum_u;
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#endif
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for (i = 0; i < 148; i++) {
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sum_u += ((unsigned char*)&tar)[i];
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#if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
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sum_s += ((signed char*)&tar)[i];
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#endif
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}
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for (i = 156; i < 512; i++) {
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sum_u += ((unsigned char*)&tar)[i];
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#if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
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sum_s += ((signed char*)&tar)[i];
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#endif
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}
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/* Most tarfiles have tar.chksum NUL or space terminated, but
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* github.com decided to be "special" and have unterminated field:
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* 0090: 30343300 30303031 33323731 30000000 |043.000132710...|
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* ^^^^^^^^|
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* Need to use GET_OCTAL. This overwrites tar.typeflag ---+
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* (the '0' char immediately after chksum in example above) with NUL.
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*/
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tar_typeflag = (uint8_t)tar.typeflag; /* save it */
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sum = GET_OCTAL(tar.chksum);
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if (sum_u != sum
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IF_FEATURE_TAR_OLDSUN_COMPATIBILITY(&& sum_s != sum)
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) {
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bb_simple_error_msg_and_die("invalid tar header checksum");
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}
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/* GET_OCTAL trashes subsequent field, therefore we call it
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* on fields in reverse order */
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if (tar.devmajor[0]) {
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char t = tar.prefix[0];
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/* we trash prefix[0] here, but we DO need it later! */
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unsigned minor = GET_OCTAL(tar.devminor);
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unsigned major = GET_OCTAL(tar.devmajor);
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file_header->device = makedev(major, minor);
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tar.prefix[0] = t;
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}
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/* 0 is reserved for high perf file, treat as normal file */
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if (tar_typeflag == '\0') tar_typeflag = '0';
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parse_names = (tar_typeflag >= '0' && tar_typeflag <= '7');
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file_header->link_target = NULL;
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if (!p_linkname && parse_names && tar.linkname[0]) {
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file_header->link_target = xstrndup(tar.linkname, sizeof(tar.linkname));
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/* FIXME: what if we have non-link object with link_target? */
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/* Will link_target be free()ed? */
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}
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#if ENABLE_FEATURE_TAR_UNAME_GNAME
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file_header->tar__uname = tar.uname[0] ? xstrndup(tar.uname, sizeof(tar.uname)) : NULL;
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file_header->tar__gname = tar.gname[0] ? xstrndup(tar.gname, sizeof(tar.gname)) : NULL;
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#endif
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file_header->mtime = GET_OCTAL(tar.mtime);
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file_header->size = GET_OCTAL(tar.size);
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file_header->gid = GET_OCTAL(tar.gid);
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file_header->uid = GET_OCTAL(tar.uid);
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/* Set bits 0-11 of the files mode */
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file_header->mode = 07777 & GET_OCTAL(tar.mode);
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file_header->name = NULL;
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if (!p_longname && parse_names) {
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/* we trash mode[0] here, it's ok */
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//tar.name[sizeof(tar.name)] = '\0'; - gcc 4.3.0 would complain
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tar.mode[0] = '\0';
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if (tar.prefix[0]) {
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/* and padding[0] */
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//tar.prefix[sizeof(tar.prefix)] = '\0'; - gcc 4.3.0 would complain
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tar.padding[0] = '\0';
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file_header->name = concat_path_file(tar.prefix, tar.name);
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} else
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file_header->name = xstrdup(tar.name);
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}
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switch (tar_typeflag) {
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case '1': /* hardlink */
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/* we mark hardlinks as regular files with zero size and a link name */
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file_header->mode |= S_IFREG;
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/* on size of link fields from star(4)
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* ... For tar archives written by pre POSIX.1-1988
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* implementations, the size field usually contains the size of
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* the file and needs to be ignored as no data may follow this
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* header type. For POSIX.1-1988 compliant archives, the size
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* field needs to be 0. For POSIX.1-2001 compliant archives,
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* the size field may be non zero, indicating that file data is
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* included in the archive.
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* i.e; always assume this is zero for safety.
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*/
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goto size0;
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case '7':
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/* case 0: */
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case '0':
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#if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
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if (file_header->name && last_char_is(file_header->name, '/')) {
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goto set_dir;
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}
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#endif
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file_header->mode |= S_IFREG;
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break;
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case '2':
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file_header->mode |= S_IFLNK;
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/* have seen tarballs with size field containing
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* the size of the link target's name */
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size0:
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file_header->size = 0;
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break;
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case '3':
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file_header->mode |= S_IFCHR;
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goto size0; /* paranoia */
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case '4':
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file_header->mode |= S_IFBLK;
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goto size0;
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case '5':
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IF_FEATURE_TAR_OLDGNU_COMPATIBILITY(set_dir:)
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file_header->mode |= S_IFDIR;
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goto size0;
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case '6':
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file_header->mode |= S_IFIFO;
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goto size0;
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case 'g': /* pax global header */
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case 'x': { /* pax extended header */
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if ((uoff_t)file_header->size > 0xfffff) /* paranoia */
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goto skip_ext_hdr;
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process_pax_hdr(archive_handle, file_header->size, (tar_typeflag == 'g'));
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goto again_after_align;
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#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
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/* See http://www.gnu.org/software/tar/manual/html_node/Extensions.html */
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case 'L':
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/* free: paranoia: tar with several consecutive longnames */
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free(p_longname);
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/* For paranoia reasons we allocate extra NUL char */
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die_if_bad_fnamesize(file_header->size);
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p_longname = xzalloc(file_header->size + 1);
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/* We read ASCIZ string, including NUL */
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xread(archive_handle->src_fd, p_longname, file_header->size);
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archive_handle->offset += file_header->size;
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/* return get_header_tar(archive_handle); */
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/* gcc 4.1.1 didn't optimize it into jump */
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/* so we will do it ourself, this also saves stack */
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goto again;
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case 'K':
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free(p_linkname);
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die_if_bad_fnamesize(file_header->size);
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p_linkname = xzalloc(file_header->size + 1);
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xread(archive_handle->src_fd, p_linkname, file_header->size);
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archive_handle->offset += file_header->size;
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/* return get_header_tar(archive_handle); */
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goto again;
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/*
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* case 'S': // Sparse file
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* Was seen in the wild. Not supported (yet?).
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* See https://www.gnu.org/software/tar/manual/html_section/tar_92.html
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* for the format. (An "Old GNU Format" was seen, not PAX formats).
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*/
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// case 'D': /* GNU dump dir */
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// case 'M': /* Continuation of multi volume archive */
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// case 'N': /* Old GNU for names > 100 characters */
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case 'V': /* Volume header */
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; /* Fall through to skip it */
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#endif
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}
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skip_ext_hdr:
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{
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off_t sz;
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bb_error_msg("warning: skipping header '%c'", tar_typeflag);
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sz = (file_header->size + 511) & ~(off_t)511;
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archive_handle->offset += sz;
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sz >>= 9; /* sz /= 512 but w/o contortions for signed div */
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while (sz--)
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xread(archive_handle->src_fd, &tar, 512);
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/* return get_header_tar(archive_handle); */
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goto again_after_align;
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}
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default:
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bb_error_msg_and_die("unknown typeflag: 0x%x", tar_typeflag);
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}
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#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
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if (p_longname) {
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file_header->name = p_longname;
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p_longname = NULL;
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}
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if (p_linkname) {
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file_header->link_target = p_linkname;
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|
p_linkname = NULL;
|
|
}
|
|
#endif
|
|
|
|
/* Everything up to and including last ".." component is stripped */
|
|
overlapping_strcpy(file_header->name, strip_unsafe_prefix(file_header->name));
|
|
//TODO: do the same for file_header->link_target?
|
|
|
|
/* 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->action_data(archive_handle);
|
|
if (archive_handle->accept || archive_handle->reject
|
|
|| (archive_handle->ah_flags & ARCHIVE_REMEMBER_NAMES)
|
|
) {
|
|
llist_add_to(&archive_handle->passed, file_header->name);
|
|
} else /* Caller isn't interested in list of unpacked files */
|
|
free(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)!
|
|
* It might be inserted in archive_handle->passed - see above */
|
|
#if ENABLE_FEATURE_TAR_UNAME_GNAME
|
|
free(file_header->tar__uname);
|
|
free(file_header->tar__gname);
|
|
#endif
|
|
return EXIT_SUCCESS; /* "decoded one header" */
|
|
}
|