From cce8b4d15e080164c3194e7e8b73270518e93100 Mon Sep 17 00:00:00 2001
From: Winford <winford@object.stream>
Date: Fri, 23 May 2025 19:55:38 +0000
Subject: [PATCH] Support OTP-28 uncompressed literals

Handle new OTP-28 uncompressed literals when running on OTP 28 and later, continues to support zlib
compression for literals with earlier OTP versions.

Adds OTP-28 to the workflow test matrix.

Closes #30

Signed-off-by: Winford <winford@object.stream>
---
 .github/workflows/build-and-test.yaml |  2 +-
 CHANGELOG.md                          |  2 +-
 src/packbeam_api.erl                  | 32 ++++++++++++++++-----------
 3 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/.github/workflows/build-and-test.yaml b/.github/workflows/build-and-test.yaml
index b94118c..8ce0475 100644
--- a/.github/workflows/build-and-test.yaml
+++ b/.github/workflows/build-and-test.yaml
@@ -13,7 +13,7 @@ jobs:
     runs-on: "ubuntu-24.04"
     strategy:
       matrix:
-        otp: ["25", "26", "27"]
+        otp: ["25", "26", "27", "28"]
 
     steps:
     # Setup
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7de9c57..4b6b58d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,7 +5,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [0.7.4] - Unreleased
-
+- Add support for OTP-28
 
 ## [0.7.3] (2024.06.06)
 
diff --git a/src/packbeam_api.erl b/src/packbeam_api.erl
index 1f93d2b..3d1dc29 100644
--- a/src/packbeam_api.erl
+++ b/src/packbeam_api.erl
@@ -586,7 +586,7 @@ filter_modules(Modules, ParsedFiles) ->
 %% @private
 parse_file(beam, _ModuleName, Data, IncludeLines) ->
     {ok, Module, Chunks} = beam_lib:all_chunks(Data),
-    {UncompressedChunks, UncompressedLiterals} = uncompress_literals(Chunks),
+    {UncompressedChunks, UncompressedLiterals} = maybe_uncompress_literals(Chunks),
     FilteredChunks = filter_chunks(UncompressedChunks, IncludeLines),
     {ok, Binary} = beam_lib:build_module(FilteredChunks),
     {ok, {Module, ChunkRefs}} = beam_lib:chunks(Data, [imports, exports, atoms]),
@@ -707,23 +707,29 @@ strip_padding(Data) ->
     Data.
 
 %% @private
-uncompress_literals(Chunks) ->
+maybe_uncompress_literals(Chunks) ->
     case proplists:get_value("LitT", Chunks) of
         undefined ->
             {Chunks, undefined};
-        <<_Header:4/binary, Data/binary>> ->
-            UncompressedData = zlib:uncompress(Data),
-            {
-                lists:keyreplace(
-                    "LitT",
-                    1,
-                    Chunks,
-                    {"LitU", UncompressedData}
-                ),
-                UncompressedData
-            }
+        <<0:32, Data/binary>> ->
+            {Chunks, Data};
+        <<_Size:4/binary, Data/binary>> ->
+            do_uncompress_literals(Chunks, Data)
     end.
 
+%% @private
+do_uncompress_literals(Chunks, Data) ->
+    UncompressedData = zlib:uncompress(Data),
+    {
+        lists:keyreplace(
+            "LitT",
+            1,
+            Chunks,
+            {"LitU", UncompressedData}
+        ),
+        UncompressedData
+    }.
+
 %% @private
 write_packbeam(OutputFilePath, ParsedFiles) ->
     PackedData =