Initial community commit

Src/external_dependencies/openmpt-trunk/unarchiver/ungzip.cpp

@@ -0,0 +1,147 @@
+/*
+ * ungzip.cpp
+ * ----------
+ * Purpose: Implementation file for extracting modules from .gz archives
+ * Notes  : (currently none)
+ * Authors: OpenMPT Devs
+ * The OpenMPT source code is released under the BSD license. Read LICENSE for more details.
+ */
+
+#include "stdafx.h"
+
+#include "../common/FileReader.h"
+#include "ungzip.h"
+
+#if defined(MPT_WITH_ZLIB) || defined(MPT_WITH_MINIZ)
+
+#if defined(MPT_WITH_ZLIB)
+#include <zlib.h>
+#elif defined(MPT_WITH_MINIZ)
+#include <miniz/miniz.h>
+#endif
+
+#endif // MPT_WITH_ZLIB || MPT_WITH_MINIZ
+
+
+OPENMPT_NAMESPACE_BEGIN
+
+
+#if defined(MPT_WITH_ZLIB) || defined(MPT_WITH_MINIZ)
+
+
+CGzipArchive::CGzipArchive(const FileReader &file) : ArchiveBase(file)
+{
+	inFile.Rewind();
+	inFile.ReadStruct(header);
+
+	// Check header data + file size
+	if(header.magic1 != GZ_HMAGIC1 || header.magic2 != GZ_HMAGIC2 || header.method != GZ_HMDEFLATE || (header.flags & GZ_FRESERVED) != 0
+		|| inFile.GetLength() <= sizeof(GZheader) + sizeof(GZtrailer))
+	{
+		return;
+	}
+	ArchiveFileInfo info;
+	info.type = ArchiveFileType::Normal;
+	contents.push_back(info);
+}
+
+
+CGzipArchive::~CGzipArchive()
+{
+	return;
+}
+
+
+bool CGzipArchive::ExtractFile(std::size_t index)
+{
+	if(index >= contents.size())
+	{
+		return false;
+	}
+
+	// Read trailer
+	GZtrailer trailer;
+	inFile.Seek(inFile.GetLength() - sizeof(GZtrailer));
+	inFile.ReadStruct(trailer);
+
+	// Continue reading header
+	inFile.Seek(sizeof(GZheader));
+
+	// Extra block present? (skip the extra data)
+	if(header.flags & GZ_FEXTRA)
+	{
+		inFile.Skip(inFile.ReadUint16LE());
+	}
+
+	// Filename present? (ignore)
+	if(header.flags & GZ_FNAME)
+	{
+		while(inFile.ReadUint8() != 0);
+	}
+
+	// Comment present? (ignore)
+	if(header.flags & GZ_FCOMMENT)
+	{
+		while(inFile.ReadUint8() != 0);
+	}
+
+	// CRC16 present? (ignore)
+	if(header.flags & GZ_FHCRC)
+	{
+		inFile.Skip(2);
+	}
+
+	// Well, this is a bit small when deflated.
+	if(!inFile.CanRead(sizeof(GZtrailer)))
+	{
+		return false;
+	}
+
+	try
+	{
+		data.reserve(inFile.BytesLeft());
+	} catch(...)
+	{
+		return false;
+	}
+
+	// Inflate!
+	z_stream strm{};
+	strm.zalloc = Z_NULL;
+	strm.zfree = Z_NULL;
+	strm.opaque = Z_NULL;
+	strm.avail_in = 0;
+	strm.next_in = Z_NULL;
+	if(inflateInit2(&strm, -15) != Z_OK)
+		return false;
+	int retVal = Z_OK;
+	uint32 crc = 0;
+	auto bytesLeft = inFile.BytesLeft() - sizeof(GZtrailer);
+	do
+	{
+		std::array<char, mpt::IO::BUFFERSIZE_SMALL> inBuffer, outBuffer;
+		strm.avail_in = static_cast<uInt>(std::min(static_cast<FileReader::pos_type>(inBuffer.size()), bytesLeft));
+		inFile.ReadStructPartial(inBuffer, strm.avail_in);
+		strm.next_in = reinterpret_cast<Bytef *>(inBuffer.data());
+		bytesLeft -= strm.avail_in;
+		do
+		{
+			strm.avail_out = static_cast<uInt>(outBuffer.size());
+			strm.next_out = reinterpret_cast<Bytef *>(outBuffer.data());
+			retVal = inflate(&strm, Z_NO_FLUSH);
+			const auto output = mpt::as_span(outBuffer.data(), outBuffer.data() + outBuffer.size() - strm.avail_out);
+			crc = crc32(crc, reinterpret_cast<Bytef *>(output.data()), static_cast<uInt>(output.size()));
+			data.insert(data.end(), output.begin(), output.end());
+		} while(strm.avail_out == 0);
+	} while(retVal == Z_OK && bytesLeft);
+	inflateEnd(&strm);
+
+	// Everything went OK? Check return code, number of written bytes and CRC32.
+	return retVal == Z_STREAM_END && trailer.isize == static_cast<uint32>(strm.total_out) && trailer.crc32_ == crc;
+}
+
+
+#endif // MPT_WITH_ZLIB || MPT_WITH_MINIZ
+
+
+OPENMPT_NAMESPACE_END