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

function                                             old     new   delta
get_header_tar                                      1783    1696     -87

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 25 insertions, 24 deletions

diff --git a/archival/libarchive/get_header_tar.c b/archival/libarchive/get_header_tar.c
index aeb54190f..5c495e14e 100644
--- a/archival/libarchive/get_header_tar.c
+++ b/archival/libarchive/get_header_tar.c
@@ -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. */
+	sum_u = ' ' * sizeof(tar.chksum);
 #if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
-	sum_s = ' ' * sizeof(tar.chksum);
+	sum_s = sum_u;
 #endif
-	sum_u = ' ' * sizeof(tar.chksum);
 	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