Improving PMC delta, reducing the blast radius of compression bombs (#79)

* Improving PMC delta, reducing the blast radius of compression bombs

Author: temisu

Diff for: src/Decompressor.cpp

@@ -108,15 +108,15 @@ size_t Decompressor::getImageOffset() const noexcept
 	return 0;
 }
 
-// 1G should be enough for everyone (this is retro!)
+// 128M should be enough for everyone (this is retro!)
 size_t Decompressor::getMaxPackedSize() noexcept
 {
-	return 0x4000'0000U;
+	return 0x800'0000U;
 }
 
 size_t Decompressor::getMaxRawSize() noexcept
 {
-	return 0x4000'0000U;
+	return 0x800'0000U;
 }
 
 }

Diff for: src/LHDecompressor.cpp

@@ -1,5 +1,7 @@
 /* Copyright (C) Teemu Suutari */
 
+#include <cstring>
+
 #include "LHDecompressor.hpp"
 
 #include "InputStream.hpp"
@@ -36,7 +38,7 @@ const std::string &LHDecompressor::getSubName() const noexcept
 }
 
 // lh.library decompress
-void LHDecompressor::decompressLhLib(Buffer &rawData,const Buffer &packedData)
+size_t LHDecompressor::decompressLhLib(Buffer &rawData,const Buffer &packedData)
 {
 	ForwardInputStream inputStream{packedData,0,packedData.size()};
 	MSBBitReader<ForwardInputStream> bitReader{inputStream};
@@ -79,10 +81,14 @@ void LHDecompressor::decompressLhLib(Buffer &rawData,const Buffer &packedData)
 				else for (uint32_t i=0;i<count;i++) outputStream.writeByte(0);
 		}
 	}
+	return outputStream.getOffset();
 }
+
 void LHDecompressor::decompressImpl(Buffer &rawData,const Buffer &previousData,bool verify)
 {
-	decompressLhLib(rawData,_packedData);
+	size_t length{decompressLhLib(rawData,_packedData)};
+	if (length!=rawData.size())
+		std::memset(rawData.data()+length,0,rawData.size()-length);
 }
 
 }

Diff for: src/LHDecompressor.hpp

@@ -21,7 +21,7 @@ class LHDecompressor : public XPKDecompressor
 	static bool detectHeaderXPK(uint32_t hdr) noexcept;
 	static std::shared_ptr<XPKDecompressor> create(uint32_t hdr,uint32_t recursionLevel,const Buffer &packedData,std::shared_ptr<XPKDecompressor::State> &state,bool verify);
 
-	static void decompressLhLib(Buffer &rawData,const Buffer &packedData);
+	static size_t decompressLhLib(Buffer &rawData,const Buffer &packedData);
 
 private:
 	const Buffer	&_packedData;

Diff for: src/PMCDecompressor.cpp

@@ -1,5 +1,7 @@
 /* Copyright (C) Teemu Suutari */
 
+#include <cstring>
+
 #include "PMCDecompressor.hpp"
 #include "InputStream.hpp"
 #include "OutputStream.hpp"
@@ -60,11 +62,23 @@ size_t PMCDecompressor::getRawSize() const noexcept
 
 void PMCDecompressor::decompressImpl(Buffer &rawData,bool verify)
 {
-	// thats all folks!
+	if (rawData.size()<_rawSize)
+		throw DecompressionError();
 	ConstSubBuffer subPackedData(_packedData,12,_packedSize-12);
 
-	LHDecompressor::decompressLhLib(rawData,subPackedData);
-	if (_ver) DLTADecode::decode(rawData,rawData,0,_rawSize);
+	size_t length{LHDecompressor::decompressLhLib(rawData,subPackedData)};
+	if (!length)
+		throw DecompressionError();
+	// thats all folks!
+	if (_ver)
+	{
+		DLTADecode::decode(rawData,rawData,0,_rawSize);
+		if (length!=_rawSize)
+			std::memset(rawData.data()+length,rawData[length-1],_rawSize-length);
+	} else {
+		if (length!=_rawSize)
+			std::memset(rawData.data()+length,0,_rawSize-length);
+	}
 }
 
 }