diff options
Diffstat (limited to 'toys')
| -rw-r--r-- | toys/posix/tar.c | 60 |
1 files changed, 36 insertions, 24 deletions
diff --git a/toys/posix/tar.c b/toys/posix/tar.c index dec3fa5f..17d382d5 100644 --- a/toys/posix/tar.c +++ b/toys/posix/tar.c @@ -83,6 +83,28 @@ struct tar_hdr { prefix[155], padd[12]; }; +// Calculate packet checksum, with cksum field treated as 8 spaces +unsigned tar_cksum(void *data) +{ + unsigned i, cksum = 8*' '; + + for (i = 0; i<500; i += (i==147) ? 9 : 1) cksum += ((char *)data)[i]; + + return cksum; +} + +static int is_tar(void *pkt) +{ + char *p = pkt; + int i = 0; + + if (p[257] && memcmp("ustar", p+257, 5)) return 0; + if (p[148] != '0') return 0; + sscanf(p+148, "%8o", &i); + + return i && tar_cksum(pkt) == i; +} + // convert from int to octal (or base-256) static void itoo(char *str, int len, unsigned long long val) { @@ -111,16 +133,6 @@ static unsigned long long otoi(char *str, unsigned len) } #define OTOI(x) otoi(x, sizeof(x)) -// Calculate packet checksum, with cksum field treated as 8 spaces -static unsigned cksum(void *data) -{ - unsigned i, cksum = 8*' '; - - for (i = 0; i<500; i += (i==147) ? 9 : 1) cksum += ((char *)data)[i]; - - return cksum; -} - static void write_longname(char *name, char type) { struct tar_hdr tmp; @@ -142,7 +154,7 @@ static void write_longname(char *name, char type) // Calculate checksum. Since 512*255 = 0377000 in octal, this can never // use more than 6 digits. The last byte is ' ' for historical reasons. - itoo(tmp.chksum, sizeof(tmp.chksum)-1, cksum(&tmp)); + itoo(tmp.chksum, sizeof(tmp.chksum)-1, tar_cksum(&tmp)); tmp.chksum[7] = ' '; // write header and name, padded with NUL to block size @@ -349,7 +361,7 @@ static int add_to_tar(struct dirtree *node) } } - itoo(hdr.chksum, sizeof(hdr.chksum)-1, cksum(&hdr)); + itoo(hdr.chksum, sizeof(hdr.chksum)-1, tar_cksum(&hdr)); hdr.chksum[7] = ' '; if (FLAG(v)) dprintf(TT.fd ? 2 : 1, "%s\n", hname); @@ -552,7 +564,7 @@ static void extract_to_disk(void) } } -static void unpack_tar(struct tar_hdr *first) +static void unpack_tar(char *first) { struct double_list *walk, *delete; struct tar_hdr tar; @@ -581,14 +593,14 @@ static void unpack_tar(struct tar_hdr *first) // ensure null temination even of pathological packets tar.padd[0] = and = 0; - // Is this a valid Unix Standard TAR header? - if (memcmp(tar.magic, "ustar", 5)) error_exit("bad header"); - if (cksum(&tar) != OTOI(tar.chksum)) error_exit("bad cksum"); + // Is this a valid TAR header? + if (!is_tar(&tar)) error_exit("bad header"); TT.hdr.size = OTOI(tar.size); // If this header isn't writing something to the filesystem - if ((tar.type<'0' || tar.type>'7') && tar.type!='S') { - + if ((tar.type<'0' || tar.type>'7') && tar.type!='S' + && (*tar.magic && tar.type)) + { // Long name extension header? if (tar.type == 'K') alloread(&TT.hdr.link_target, TT.hdr.size); else if (tar.type == 'L') alloread(&TT.hdr.name, TT.hdr.size); @@ -652,6 +664,7 @@ static void unpack_tar(struct tar_hdr *first) // At this point, we have something to output. Convert metadata. TT.hdr.mode = OTOI(tar.mode); if (tar.type == 'S') TT.hdr.mode |= 0x8000; + else if (!tar.type) TT.hdr.mode = 8<<12; else TT.hdr.mode |= (char []){8,8,10,2,6,4,1,8}[tar.type-'0']<<12; TT.hdr.uid = OTOI(tar.uid); TT.hdr.gid = OTOI(tar.gid); @@ -838,17 +851,16 @@ void tar_main(void) // Are we reading? if (FLAG(x)||FLAG(t)) { - struct tar_hdr *hdr = 0; + char *hdr = 0; // autodetect compression type when not specified if (!(FLAG(j)||FLAG(z)||FLAG(J))) { - len = xread(TT.fd, hdr = (void *)(toybuf+sizeof(toybuf)-512), 512); - if (len!=512 || strncmp("ustar", hdr->magic, 5)) { + len = xread(TT.fd, hdr = toybuf+sizeof(toybuf)-512, 512); + if (len!=512 || !is_tar(hdr)) { // detect gzip and bzip signatures if (SWAP_BE16(*(short *)hdr)==0x1f8b) toys.optflags |= FLAG_z; - else if (!memcmp(hdr->name, "BZh", 3)) toys.optflags |= FLAG_j; - else if (peek_be(hdr->name, 7) == 0xfd377a585a0000) - toys.optflags |= FLAG_J; + else if (!memcmp(hdr, "BZh", 3)) toys.optflags |= FLAG_j; + else if (peek_be(hdr, 7) == 0xfd377a585a0000) toys.optflags |= FLAG_J; else error_exit("Not tar"); // if we can seek back we don't need to loop and copy data |