From b9677be8a799ecd9aecf3e612f35116e6b6ecb21 Mon Sep 17 00:00:00 2001
From: Nico Weber <thakis@chromium.org>
Date: Mon, 8 Apr 2024 20:59:24 -0400
Subject: [PATCH] LibGfx/JPEG2000: Decode COM marker segment data

We don't do anything with this (except log the contents if
JPEG2000_DEBUG is 1).

The motivation is that we now decode all marker segments that are
used in all JPEG2000 files I've seen so far, allowing us to make
remaining unknown marker types fatal.
---
 .../LibGfx/ImageFormats/JPEG2000Loader.cpp    | 33 +++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/Userland/Libraries/LibGfx/ImageFormats/JPEG2000Loader.cpp b/Userland/Libraries/LibGfx/ImageFormats/JPEG2000Loader.cpp
index 876e3db52c3..ec651f74de9 100644
--- a/Userland/Libraries/LibGfx/ImageFormats/JPEG2000Loader.cpp
+++ b/Userland/Libraries/LibGfx/ImageFormats/JPEG2000Loader.cpp
@@ -10,6 +10,7 @@
 #include <LibGfx/ImageFormats/ISOBMFF/JPEG2000Boxes.h>
 #include <LibGfx/ImageFormats/ISOBMFF/Reader.h>
 #include <LibGfx/ImageFormats/JPEG2000Loader.h>
+#include <LibTextCodec/Decoder.h>
 
 // Core coding system spec (.jp2 format): T-REC-T.800-201511-S!!PDF-E.pdf available here:
 // https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-T.800-201511-S!!PDF-E&type=items
@@ -408,6 +409,35 @@ static ErrorOr<QuantizationDefault> read_quantization_default(ReadonlyBytes data
     return qcd;
 }
 
+// A.9.2 Comment (COM)
+struct Comment {
+    enum CommentType {
+        Binary = 0,
+        ISO_IEC_8859_15 = 1,
+    };
+    CommentType type { Binary }; // "Rcom" in spec.
+    ReadonlyBytes data;
+};
+
+static ErrorOr<Comment> read_comment(ReadonlyBytes data)
+{
+    if (data.size() < 2)
+        return Error::from_string_literal("JPEG2000ImageDecoderPlugin: Not enough data for COM marker segment");
+
+    Comment com;
+    u16 comment_type = *reinterpret_cast<AK::BigEndian<u16> const*>(data.data());
+    if (comment_type > 1)
+        return Error::from_string_literal("JPEG2000ImageDecoderPlugin: Invalid comment type");
+    com.type = static_cast<Comment::CommentType>(comment_type);
+    com.data = data.slice(1);
+
+    dbgln_if(JPEG2000_DEBUG, "JPEG2000ImageDecoderPlugin: COM marker segment: comment_type={}, size()={}", (int)com.type, com.data.size());
+    if (com.type == Comment::ISO_IEC_8859_15)
+        dbgln_if(JPEG2000_DEBUG, "JPEG2000ImageDecoderPlugin: COM marker segment, ISO/IEC 8859-15 text: '{}'", TRY(TextCodec::decoder_for("ISO-8859-1"sv)->to_utf8(StringView { com.data })));
+
+    return com;
+}
+
 struct JPEG2000LoadingContext {
     enum class State {
         NotDecoded = 0,
@@ -427,6 +457,7 @@ struct JPEG2000LoadingContext {
     ImageAndTileSize siz;
     CodingStyleDefault cod;
     QuantizationDefault qcd;
+    Vector<Comment> coms;
 };
 
 struct MarkerSegment {
@@ -513,6 +544,8 @@ static ErrorOr<void> parse_codestream_main_header(JPEG2000LoadingContext& contex
                     return Error::from_string_literal("JPEG2000ImageDecoderPlugin: Multiple QCD markers in main header");
                 context.qcd = TRY(read_quantization_default(marker.data.value()));
                 saw_QCD_marker = true;
+            } else if (marker.marker == J2K_COM) {
+                context.coms.append(TRY(read_comment(marker.data.value())));
             } else {
                 // FIXME: These are valid main header markers. Parse contents.
                 dbgln("JPEG2000ImageDecoderPlugin: marker {:#04x} not yet implemented", marker.marker);