Remove fallthough-based logic from iso9660 reader

This simplifies the logic quite a bit, cuts down on code size, and
follows the principle of least surprise.

diff --git a/libarchive/archive_read_support_format_iso9660.c b/libarchive/archive_read_support_format_iso9660.c
index a165524017e3fb95bc04b5fa5249f495ec639fc9..1ffe7510830e35097fa15dc30bd54b531f3fab77 100644 (file)
--- a/libarchive/archive_read_support_format_iso9660.c
+++ b/libarchive/archive_read_support_format_iso9660.c
@@ -2066,14 +2066,9 @@ parse_rockridge(struct archive_read *a, struct file_info *file,
                int data_length = p[2] - 4;
                int version = p[3];
 
-               /*
-                * Yes, each 'if' here does test p[0] again.
-                * Otherwise, the fall-through handling to catch
-                * unsupported extensions doesn't work.
-                */
                switch(p[0]) {
                case 'C':
-                       if (p[0] == 'C' && p[1] == 'E') {
+                       if (p[1] == 'E') {
                                if (version == 1 && data_length == 24) {
                                        /*
                                         * CE extension comprises:
@@ -2091,53 +2086,42 @@ parse_rockridge(struct archive_read *a, struct file_info *file,
                                            != ARCHIVE_OK)
                                                return (ARCHIVE_FATAL);
                                }
-                               break;
                        }
-                       if (p[0] == 'C' && p[1] == 'L') {
+                       else if (p[1] == 'L') {
                                if (version == 1 && data_length == 8) {
                                        file->cl_offset = (uint64_t)
                                            iso9660->logical_block_size *
                                            (uint64_t)archive_le32dec(data);
                                        iso9660->seenRockridge = 1;
                                }
-                               break;
                        }
-                       /* FALLTHROUGH */
+                       break;
                case 'N':
-                       if (p[0] == 'N' && p[1] == 'M') {
+                       if (p[1] == 'M') {
                                if (version == 1) {
                                        parse_rockridge_NM1(file,
                                            data, data_length);
                                        iso9660->seenRockridge = 1;
                                }
-                               break;
                        }
-                       /* FALLTHROUGH */
+                       break;
                case 'P':
-                       if (p[0] == 'P' && p[1] == 'D') {
-                               /*
-                                * PD extension is padding;
-                                * contents are always ignored.
-                                */
-                               break;
-                       }
-                       if (p[0] == 'P' && p[1] == 'L') {
-                               /*
-                                * PL extension won't appear;
-                                * contents are always ignored.
-                                */
-                               break;
-                       }
-                       if (p[0] == 'P' && p[1] == 'N') {
+                       /*
+                        * PD extension is padding;
+                        * contents are always ignored.
+                        *
+                        * PL extension won't appear;
+                        * contents are always ignored.
+                        */
+                       if (p[1] == 'N') {
                                if (version == 1 && data_length == 16) {
                                        file->rdev = toi(data,4);
                                        file->rdev <<= 32;
                                        file->rdev |= toi(data + 8, 4);
                                        iso9660->seenRockridge = 1;
                                }
-                               break;
                        }
-                       if (p[0] == 'P' && p[1] == 'X') {
+                       else if (p[1] == 'X') {
                                /*
                                 * PX extension comprises:
                                 *   8 bytes for mode,
@@ -2164,35 +2148,31 @@ parse_rockridge(struct archive_read *a, struct file_info *file,
                                                    = toi(data + 32, 4);
                                        iso9660->seenRockridge = 1;
                                }
-                               break;
                        }
-                       /* FALLTHROUGH */
+                       break;
                case 'R':
-                       if (p[0] == 'R' && p[1] == 'E' && version == 1) {
+                       if (p[1] == 'E' && version == 1) {
                                file->re = 1;
                                iso9660->seenRockridge = 1;
-                               break;
                        }
-                       if (p[0] == 'R' && p[1] == 'R' && version == 1) {
+                       else if (p[1] == 'R' && version == 1) {
                                /*
                                 * RR extension comprises:
                                 *    one byte flag value
                                 * This extension is obsolete,
                                 * so contents are always ignored.
                                 */
-                               break;
                        }
-                       /* FALLTHROUGH */
+                       break;
                case 'S':
-                       if (p[0] == 'S' && p[1] == 'L') {
+                       if (p[1] == 'L') {
                                if (version == 1) {
                                        parse_rockridge_SL1(file,
                                            data, data_length);
                                        iso9660->seenRockridge = 1;
                                }
-                               break;
                        }
-                       if (p[0] == 'S' && p[1] == 'T'
+                       else if (p[1] == 'T'
                            && data_length == 0 && version == 1) {
                                /*
                                 * ST extension marks end of this
@@ -2207,32 +2187,27 @@ parse_rockridge(struct archive_read *a, struct file_info *file,
                                iso9660->seenRockridge = 0;
                                return (ARCHIVE_OK);
                        }
+                       break;
                case 'T':
-                       if (p[0] == 'T' && p[1] == 'F') {
+                       if (p[1] == 'F') {
                                if (version == 1) {
                                        parse_rockridge_TF1(file,
                                            data, data_length);
                                        iso9660->seenRockridge = 1;
                                }
-                               break;
                        }
-                       /* FALLTHROUGH */
+                       break;
                case 'Z':
-                       if (p[0] == 'Z' && p[1] == 'F') {
+                       if (p[1] == 'F') {
                                if (version == 1)
                                        parse_rockridge_ZF1(file,
                                            data, data_length);
-                               break;
                        }
-                       /* FALLTHROUGH */
+                       break;
                default:
-                       /* The FALLTHROUGHs above leave us here for
-                        * any unsupported extension. */
                        break;
                }
 
-
-
                p += p[2];
        }
        return (ARCHIVE_OK);