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tar: accomodate non-terminated tar.chksum fields as seen from github.com

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function                                             old     new   delta
get_header_tar                                      1783    1696     -87

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2018-01-27 19:04:08 +01:00
parent 277636670c
commit 20f02c3c87
1 changed files with 26 additions and 25 deletions
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51
archival/libarchive/get_header_tar.c
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@ -152,6 +152,7 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
file_header_t *file_header = archive_handle->file_header;
struct tar_header_t tar;
char *cp;
int tar_typeflag; /* can be "char", "int" seems give smaller code */
int i, sum_u, sum;
#if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
int sum_s;
@ -253,10 +254,10 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
* 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);
#if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
sum_s = sum_u;
#endif
for (i = 0; i < 148; i++) {
sum_u += ((unsigned char*)&tar)[i];
#if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
@ -269,27 +270,22 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
sum_s += ((signed char*)&tar)[i];
#endif
}
/* This field does not need special treatment (getOctal) */
{
char *endp; /* gcc likes temp var for &endp */
sum = strtoul(tar.chksum, &endp, 8);
if ((*endp != '\0' && *endp != ' ')
|| (sum_u != sum IF_FEATURE_TAR_OLDSUN_COMPATIBILITY(&& sum_s != sum))
) {
bb_error_msg_and_die("invalid tar header checksum");
}
}
/* don't use xstrtoul, tar.chksum may have leading spaces */
sum = strtoul(tar.chksum, NULL, 8);
if (sum_u != sum IF_FEATURE_TAR_OLDSUN_COMPATIBILITY(&& sum_s != sum)) {
/* Most tarfiles have tar.chksum NUL or space terminated, but
* github.com decided to be "special" and have unterminated field:
* 0090: 30343300 30303031 33323731 30000000 |043.000132710...|
* ^^^^^^^^|
* Need to use GET_OCTAL. This overwrites tar.typeflag ---+
* (the '0' char immediately after chksum in example above) with NUL.
*/
tar_typeflag = (uint8_t)tar.typeflag; /* save it */
sum = GET_OCTAL(tar.chksum);
if (sum_u != sum
IF_FEATURE_TAR_OLDSUN_COMPATIBILITY(&& sum_s != sum)
) {
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
/* GET_OCTAL trashes subsequent field, therefore we call it
* on fields in reverse order */
if (tar.devmajor[0]) {
char t = tar.prefix[0];
@ -299,6 +295,11 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
file_header->device = makedev(major, minor);
tar.prefix[0] = t;
}
/* 0 is reserved for high perf file, treat as normal file */
if (tar_typeflag == '\0') tar_typeflag = '0';
parse_names = (tar_typeflag >= '0' && tar_typeflag <= '7');
file_header->link_target = NULL;
if (!p_linkname && parse_names && tar.linkname[0]) {
file_header->link_target = xstrndup(tar.linkname, sizeof(tar.linkname));
@ -332,7 +333,7 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
/* Set bits 12-15 of the files mode */
/* (typeflag was not trashed because chksum does not use getOctal) */
switch (tar.typeflag) {
switch (tar_typeflag) {
case '1': /* hardlink */
/* we mark hardlinks as regular files with zero size and a link name */
file_header->mode |= S_IFREG;
@ -381,7 +382,7 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
case 'x': { /* pax extended header */
if ((uoff_t)file_header->size > 0xfffff) /* paranoia */
goto skip_ext_hdr;
process_pax_hdr(archive_handle, file_header->size, (tar.typeflag == 'g'));
process_pax_hdr(archive_handle, file_header->size, (tar_typeflag == 'g'));
goto again_after_align;
#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
/* See http://www.gnu.org/software/tar/manual/html_node/Extensions.html */
@ -419,7 +420,7 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
skip_ext_hdr:
{
off_t sz;
bb_error_msg("warning: skipping header '%c'", tar.typeflag);
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 */
@ -429,7 +430,7 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
goto again_after_align;
}
default:
bb_error_msg_and_die("unknown typeflag: 0x%x", tar.typeflag);
bb_error_msg_and_die("unknown typeflag: 0x%x", tar_typeflag);
}
#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS