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