mime: fix zstd detect

antgroup · Dec 23, 2024 · 147ba5c · 147ba5c
1 parent 4d27a88
commit 147ba5c
Showing 1 changed file with 8 additions and 3 deletions.
diff --git a/modules/mime/internal/magic/archive.go b/modules/mime/internal/magic/archive.go
@@ -52,10 +52,15 @@ func InstallShieldCab(raw []byte, _ uint32) bool {
 }
 
 // Zstd matches a Zstandard archive file.
+// https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md
 func Zstd(raw []byte, limit uint32) bool {
-	return len(raw) >= 4 &&
-		(0x22 <= raw[0] && raw[0] <= 0x28 || raw[0] == 0x1E) && // Different Zstandard versions.
-		bytes.HasPrefix(raw[1:], []byte{0xB5, 0x2F, 0xFD})
+	if len(raw) < 4 {
+		return false
+	}
+	sig := binary.LittleEndian.Uint32(raw)
+	// Check for Zstandard frames and skippable frames.
+	return (sig >= 0xFD2FB522 && sig <= 0xFD2FB528) ||
+		(sig >= 0x184D2A50 && sig <= 0x184D2A5F)
 }
 
 // CRX matches a Chrome extension file: a zip archive prepended by a package header.