Add extra comments, freakout if a pax archive is encoutered.

diff --git a/archival/libunarchive/get_header_tar.c b/archival/libunarchive/get_header_tar.c
index fbca0f274821ad6c48bafdbc2d109a94027fb1cf..013450a2aae44bcdc14ee600d2639f54a474740d 100644 (file)
--- a/archival/libunarchive/get_header_tar.c
+++ b/archival/libunarchive/get_header_tar.c
@@ -16,6 +16,11 @@
  *  FIXME: Better checking required in oldcompatability mode, 
  *  the file db.1.85.tar.gz from sleepycat.com has trailing garbage
  *  GNU tar can handle it, busybox tar reports invalid tar header. 
+ *
+ *  References:
+ *    GNU tar and star man pages,
+ *    Opengroup's ustar interchange format,
+ *             http://www.opengroup.org/onlinepubs/007904975/utilities/pax.html
  */
 
 #include <stdio.h>
@@ -122,6 +127,14 @@ extern char get_header_tar(archive_handle_t *archive_handle)
 
        /* Fix mode, used by the old format */
        switch (tar.formated.typeflag) {
+       /* busybox identifies hard links as being regular files with 0 size and a link name */
+       case '1':
+               file_header->mode &= (S_IFREG | 07777);
+               break;
+       case 'x':
+       case 'g':
+               bb_error_msg_and_die("pax is not tar");
+               break;
 #ifdef CONFIG_FEATURE_TAR_OLDGNU_COMPATABILITY
        case 0:
        case '0':
@@ -146,11 +159,11 @@ extern char get_header_tar(archive_handle_t *archive_handle)
        case '6':
                file_header->mode |= S_IFIFO;
                break;
-#endif
-       /* hard links are detected as regular files with 0 size and a link name */
-       case '1':
-               file_header->mode &= (S_IFREG | 07777);
+       case '7':
+               /* Reserved for high performance files, treat as normal file */
+               file_header->mode |= S_IFREG;
                break;
+#endif
 #ifdef CONFIG_FEATURE_TAR_GNU_EXTENSIONS
        case 'L': {
                        longname = xmalloc(file_header->size + 1);
@@ -169,13 +182,15 @@ extern char get_header_tar(archive_handle_t *archive_handle)
                        file_header->name = linkname;
                        return(get_header_tar(archive_handle));
                }
-       case 'D':
-       case 'M':
-       case 'N':
-       case 'S':
-       case 'V':
+       case 'D':       /* GNU dump dir */
+       case 'M':       /* Continuation of multi volume archive*/
+       case 'N':       /* Old GNU for names > 100 characters */
+       case 'S':       /* Sparse file */
+       case 'V':       /* Volume header */
                bb_error_msg("Ignoring GNU extension type %c", tar.formated.typeflag);
 #endif
+       default:
+               bb_error_msg("Unknown typeflag: 0x%x", tar.formated.typeflag);
        }
        {       /* Strip trailing '/' in directories */
                /* Must be done after mode is set as '/' is used to check if its a directory */