From 292705ddc3b96dee96f742bc327c73d1c8618b92 Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@users.noreply.github.com>
Date: Wed, 13 Dec 2023 16:57:49 +0100
Subject: [PATCH] fixed OpenDecompressor flag handling.

---
 src/common/filesystem/include/fs_files.h      | 11 +++++++++--
 .../filesystem/source/files_decompress.cpp    | 19 +++++++++++--------
 src/common/filesystem/source/resourcefile.cpp |  2 +-
 src/maploader/maploader.cpp                   |  4 ++--
 4 files changed, 23 insertions(+), 13 deletions(-)

diff --git a/src/common/filesystem/include/fs_files.h b/src/common/filesystem/include/fs_files.h
index 650226877..b7d314837 100644
--- a/src/common/filesystem/include/fs_files.h
+++ b/src/common/filesystem/include/fs_files.h
@@ -73,7 +73,7 @@ public:
 };
 
 // Zip compression methods, extended by some internal types to be passed to OpenDecompressor
-enum
+enum ECompressionMethod
 {
 	METHOD_STORED = 0,
 	METHOD_SHRINK = 1,
@@ -96,6 +96,13 @@ enum
 	METHOD_TRANSFEROWNER = 0x8000,
 };
 
+enum EDecompressFlags
+{
+	DCF_TRANSFEROWNER = 1,
+	DCF_SEEKABLE = 2,
+	DCF_EXCEPTIONS = 4
+};
+
 class FileReader;
 
 // an opaque memory buffer to the file's content. Can either own the memory or just point to an external buffer.
@@ -283,7 +290,7 @@ public:
 	bool OpenMemoryArray(std::vector<uint8_t>& data);	// take the given array
 	bool OpenMemoryArray(FileData& data);	// take the given array
 	bool OpenMemoryArray(std::function<bool(std::vector<uint8_t>&)> getter);	// read contents to a buffer and return a reader to it
-	bool OpenDecompressor(FileReader &parent, Size length, int method, bool seekable, bool exceptions = false);	// creates a decompressor stream. 'seekable' uses a buffered version so that the Seek and Tell methods can be used.
+	bool OpenDecompressor(FileReader &parent, Size length, int method, int flags = 0);	// creates a decompressor stream. 'seekable' uses a buffered version so that the Seek and Tell methods can be used.
 
 	Size Tell() const
 	{
diff --git a/src/common/filesystem/source/files_decompress.cpp b/src/common/filesystem/source/files_decompress.cpp
index 62c85b3a2..0bbb80c52 100644
--- a/src/common/filesystem/source/files_decompress.cpp
+++ b/src/common/filesystem/source/files_decompress.cpp
@@ -848,14 +848,16 @@ public:
 };
 
 
-bool FileReader::OpenDecompressor(FileReader &parent, Size length, int method, bool seekable, bool exceptions)
+bool FileReader::OpenDecompressor(FileReader &parent, Size length, int method, int flags)
 {
 	FileReaderInterface* fr = nullptr;
 	DecompressorBase* dec = nullptr;
 	try
 	{
 		FileReader* p = &parent;
-		switch (method & ~METHOD_TRANSFEROWNER)
+		bool exceptions = !!(flags & DCF_EXCEPTIONS);
+
+		switch (method)
 		{
 		case METHOD_DEFLATE:
 		case METHOD_ZLIB:
@@ -975,13 +977,13 @@ bool FileReader::OpenDecompressor(FileReader &parent, Size length, int method, b
 		}
 		if (dec)
 		{
-			if (method & METHOD_TRANSFEROWNER)
+			if (flags & DCF_TRANSFEROWNER)
 			{
 				dec->SetOwnsReader();
 			}
 			dec->Length = length;
 		}
-		if (!seekable)
+		if (!(flags & DCF_SEEKABLE))
 		{
 			Close();
 			mReader = fr;
@@ -1003,16 +1005,17 @@ bool FileReader::OpenDecompressor(FileReader &parent, Size length, int method, b
 
 bool FCompressedBuffer::Decompress(char* destbuffer)
 {
-	FileReader mr;
-	mr.OpenMemory(mBuffer, mCompressedSize);
 	if (mMethod == METHOD_STORED)
 	{
-		return mr.Read(destbuffer, mSize) != mSize;
+		memcpy(destbuffer, mBuffer, mSize);
+		return true;
 	}
 	else
 	{
+		FileReader mr;
+		mr.OpenMemory(mBuffer, mCompressedSize);
 		FileReader frz;
-		if (frz.OpenDecompressor(mr, mSize, mMethod, false, false))
+		if (frz.OpenDecompressor(mr, mSize, mMethod))
 		{
 			return frz.Read(destbuffer, mSize) != mSize;
 		}
diff --git a/src/common/filesystem/source/resourcefile.cpp b/src/common/filesystem/source/resourcefile.cpp
index 2b5fa5d48..a13f62e64 100644
--- a/src/common/filesystem/source/resourcefile.cpp
+++ b/src/common/filesystem/source/resourcefile.cpp
@@ -564,7 +564,7 @@ FileReader FResourceFile::GetEntryReader(uint32_t entry, bool newreader)
 		{
 			FileReader fri;
 			fri.OpenFilePart(Reader, Entries[entry].Position, Entries[entry].CompressedSize);
-			fr.OpenDecompressor(fri, Entries[entry].Length, Entries[entry].Method | METHOD_TRANSFEROWNER, true, true);
+			fr.OpenDecompressor(fri, Entries[entry].Length, Entries[entry].Method, FileSys::DCF_TRANSFEROWNER | FileSys::DCF_SEEKABLE | FileSys::DCF_EXCEPTIONS);
 		}
 	}
 	return fr;
diff --git a/src/maploader/maploader.cpp b/src/maploader/maploader.cpp
index 727415be1..d6ae5d4ff 100644
--- a/src/maploader/maploader.cpp
+++ b/src/maploader/maploader.cpp
@@ -738,7 +738,7 @@ bool MapLoader::LoadExtendedNodes (FileReader &dalump, uint32_t id)
 		if (compressed)
 		{
 			FileReader zip;
-			if (zip.OpenDecompressor(dalump, -1, FileSys::METHOD_ZLIB, false, true))
+			if (zip.OpenDecompressor(dalump, -1, FileSys::METHOD_ZLIB, FileSys::DCF_EXCEPTIONS))
 			{
 				LoadZNodes(zip, type);
 				return true;
@@ -3344,7 +3344,7 @@ void MapLoader::LoadLightmap(MapData *map)
 		return;
 
 	FileReader fr;
-	if (!fr.OpenDecompressor(map->Reader(ML_LIGHTMAP), -1, FileSys::METHOD_ZLIB, false, false))
+	if (!fr.OpenDecompressor(map->Reader(ML_LIGHTMAP), -1, FileSys::METHOD_ZLIB))
 		return;