commit 7176120d5815eff277f385b2778d6f99093b2de5
author Wan-Teh Chang <wtc@google.com> Thu Aug 22 10:21:02 2024 -0700
committer Wan-Teh Chang <wtc@google.com> Thu Aug 22 12:53:29 2024 -0700
tree a9030ab8a6280f74c97dad0871e999167e269968
parent 9be2966e6bcd04ca9b801e9fe4f0d202cfb9fbed

Also check the type "skip" for a FreeSpaceBox

The type of a FreeSpaceBox can be "free" or "skip".

A follow-up to https://github.com/AOMediaCodec/libavif/pull/2398.

src/read.c

diff --git a/src/read.c b/src/read.c
index 612c1c2..6a122cc 100644
--- a/src/read.c
+++ b/src/read.c
@@ -4153,7 +4153,8 @@
         }
 #endif
 
-        if (!isFtyp && (isNonSkippableVariableLengthBox || !memcmp(header.type, "free", 4) || !memcmp(header.type, "mdat", 4))) {
+        if (!isFtyp && (isNonSkippableVariableLengthBox || !memcmp(header.type, "free", 4) || !memcmp(header.type, "skip", 4) ||
+                        !memcmp(header.type, "mdat", 4))) {
             // Section 6.3.4 of ISO/IEC 14496-12:
             //   The FileTypeBox shall occur before any variable-length box (e.g. movie, free space, media data).
             AVIF_CHECKERR(ftypSeen, AVIF_RESULT_BMFF_PARSE_FAILED);