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common/compression/zlib.cpp

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifdef __MORPHOS__
+  #define _NO_PPCINLINE
+  #include <zlib.h>
+  #undef _NO_PPCINLINE
+#else
+  #include <zlib.h>
+#endif
+
+#if ZLIB_VERNUM < 0x1204
+#error Version 1.2.0.4 or newer of zlib is required for this code
+#endif
+
+#include "common/compression/deflate.h"
+
+#include "common/ptr.h"
+#include "common/util.h"
+#include "common/stream.h"
+#include "common/debug.h"
+#include "common/textconsole.h"
+
+
+namespace Common {
+
+bool inflateZlib(byte *dst, unsigned long *dstLen, const byte *src, unsigned long srcLen) {
+	return Z_OK == uncompress(dst, dstLen, src, srcLen);
+}
+
+bool inflateZlibHeaderless(byte *dst, uint *dstLen, const byte *src, uint srcLen, const byte *dict, uint dictLen) {
+	if (!dst || !dstLen || !*dstLen || !src || !srcLen)
+		return false;
+
+	// Initialize zlib
+	z_stream stream;
+	stream.next_in = const_cast<byte *>(src);
+	stream.avail_in = srcLen;
+	stream.next_out = dst;
+	stream.avail_out = *dstLen;
+	stream.zalloc = Z_NULL;
+	stream.zfree = Z_NULL;
+	stream.opaque = Z_NULL;
+
+	// Negative MAX_WBITS tells zlib there's no zlib header
+	int err = inflateInit2(&stream, -MAX_WBITS);
+	if (err != Z_OK)
+		return false;
+
+	// Set the dictionary, if provided
+	if (dict != nullptr) {
+		err = inflateSetDictionary(&stream, const_cast<byte *>(dict), dictLen);
+		if (err != Z_OK) {
+			inflateEnd(&stream);
+			return false;
+		}
+	}
+
+	err = inflate(&stream, Z_SYNC_FLUSH);
+	if (err != Z_OK && err != Z_STREAM_END) {
+		inflateEnd(&stream);
+		return false;
+	}
+
+	inflateEnd(&stream);
+	*dstLen = *dstLen - stream.avail_out;
+	return true;
+}
+
+#ifndef RELEASE_BUILD
+static bool _shownBackwardSeekingWarning = false;
+#endif
+
+/**
+ * A simple wrapper class which can be used to wrap around an arbitrary
+ * other SeekableReadStream and will then provide on-the-fly decompression support.
+ * Assumes the compressed data to be in gzip format.
+ */
+class GZipReadStream : public SeekableReadStream {
+protected:
+	enum {
+		BUFSIZE = 16384		// 1 << MAX_WBITS
+	};
+
+	byte	_buf[BUFSIZE];
+
+	DisposablePtr<SeekableReadStream> _wrapped;
+	z_stream _stream;
+	int _zlibErr;
+	uint64 _parentPos;
+	uint32 _pos;
+	uint32 _origSize;
+	bool _eos;
+
+public:
+
+	GZipReadStream(SeekableReadStream *w, DisposeAfterUse::Flag disposeParent, uint32 knownSize) : _wrapped(w, disposeParent), _stream() {
+		assert(w != nullptr);
+
+		_parentPos = w->pos();
+		// Verify file header is correct
+		uint16 header = w->readUint16BE();
+		assert(header == 0x1F8B ||
+		       ((header & 0x0F00) == 0x0800 && header % 31 == 0));
+
+		if (header == 0x1F8B) {
+			// Retrieve the original file size
+			w->seek(-4, SEEK_END);
+			_origSize = w->readUint32LE();
+		} else {
+			// Original size not available in zlib format
+			// use an otherwise known size if supplied.
+			_origSize = knownSize;
+		}
+		w->seek(_parentPos, SEEK_SET);
+		_pos = 0;
+		_eos = false;
+
+		// Adding 32 to windowBits indicates to zlib that it is supposed to
+		// automatically detect whether gzip or zlib headers are used for
+		// the compressed file. This feature was added in zlib 1.2.0.4,
+		// released 10 August 2003.
+		// Note: This is *crucial* for savegame compatibility, do *not* remove!
+		_zlibErr = inflateInit2(&_stream, MAX_WBITS + 32);
+		if (_zlibErr != Z_OK)
+			return;
+
+		// Setup input buffer
+		_stream.next_in = _buf;
+		_stream.avail_in = 0;
+	}
+
+	GZipReadStream(SeekableReadStream *w, DisposeAfterUse::Flag disposeParent, uint32 knownSize, const byte *dict, uint dictLen) : _wrapped(w, disposeParent), _stream() {
+		assert(w != nullptr);
+
+		_parentPos = w->pos();
+		// This is headerless deflate
+		// Original size not available
+		// use an otherwise known size if supplied.
+		_origSize = knownSize;
+		_pos = 0;
+		_eos = false;
+
+		_zlibErr = inflateInit2(&_stream, -MAX_WBITS);
+		if (_zlibErr != Z_OK)
+			return;
+
+		// Set the dictionary, if provided
+		if (dict != nullptr && dictLen > 0) {
+			_zlibErr = inflateSetDictionary(&_stream, const_cast<byte *>(dict), dictLen);
+			if (_zlibErr != Z_OK)
+				return;
+		}
+
+		// Setup input buffer
+		_stream.next_in = _buf;
+		_stream.avail_in = 0;
+	}
+
+	~GZipReadStream() {
+		inflateEnd(&_stream);
+	}
+
+	bool err() const override { return (_zlibErr != Z_OK) && (_zlibErr != Z_STREAM_END); }
+	void clearErr() override {
+		// only reset _eos; I/O errors are not recoverable
+		_eos = false;
+	}
+
+	uint32 read(void *dataPtr, uint32 dataSize) override {
+		_stream.next_out = (byte *)dataPtr;
+		_stream.avail_out = dataSize;
+
+		// Keep going while we get no error
+		while (_zlibErr == Z_OK && _stream.avail_out) {
+			if (_stream.avail_in == 0 && !_wrapped->eos()) {
+				// If we are out of input data: Read more data, if available.
+				_stream.next_in = _buf;
+				_stream.avail_in = _wrapped->read(_buf, BUFSIZE);
+			}
+			_zlibErr = inflate(&_stream, Z_NO_FLUSH);
+		}
+
+		// Update the position counter
+		_pos += dataSize - _stream.avail_out;
+
+		if (_zlibErr == Z_STREAM_END && _stream.avail_out > 0)
+			_eos = true;
+
+		return dataSize - _stream.avail_out;
+	}
+
+	bool eos() const override {
+		return _eos;
+	}
+	int64 pos() const override {
+		return _pos;
+	}
+	int64 size() const override {
+		return _origSize;
+	}
+	bool seek(int64 offset, int whence = SEEK_SET) override {
+		int32 newPos = 0;
+		switch (whence) {
+		default:
+			// fallthrough intended
+		case SEEK_SET:
+			newPos = offset;
+			break;
+		case SEEK_CUR:
+			newPos = _pos + offset;
+			break;
+		case SEEK_END:
+			// NOTE: This can be an expensive operation (see below).
+			newPos = size() + offset;
+			break;
+		}
+
+		assert(newPos >= 0);
+
+		if ((uint32)newPos < _pos) {
+			// To search backward, we have to restart the whole decompression
+			// from the start of the file. A rather wasteful operation, best
+			// to avoid it. :/
+
+#ifndef RELEASE_BUILD
+			if (!_shownBackwardSeekingWarning) {
+				// We only throw this warning once per stream, to avoid
+				// getting the console swarmed with warnings when consecutive
+				// seeks are made.
+				debug(1, "Backward seeking in GZipReadStream detected");
+				_shownBackwardSeekingWarning = true;
+			}
+#endif
+
+			_pos = 0;
+			_wrapped->seek(_parentPos, SEEK_SET);
+			_zlibErr = inflateReset(&_stream);
+			if (_zlibErr != Z_OK)
+				return false; // FIXME: STREAM REWRITE
+			_stream.next_in = _buf;
+			_stream.avail_in = 0;
+		}
+
+		offset = newPos - _pos;
+
+		// Skip the given amount of data (very inefficient if one tries to skip
+		// huge amounts of data, but usually client code will only skip a few
+		// bytes, so this should be fine.
+		byte tmpBuf[1024];
+		while (!err() && offset > 0) {
+			offset -= read(tmpBuf, MIN((int64)sizeof(tmpBuf), offset));
+		}
+
+		_eos = false;
+		return true; // FIXME: STREAM REWRITE
+	}
+};
+
+/**
+ * A simple wrapper class which can be used to wrap around an arbitrary
+ * other WriteStream and will then provide on-the-fly compression support.
+ * The compressed data is written in the gzip format.
+ */
+class GZipWriteStream : public WriteStream {
+protected:
+	enum {
+		BUFSIZE = 16384		// 1 << MAX_WBITS
+	};
+
+	byte	_buf[BUFSIZE];
+	ScopedPtr<WriteStream> _wrapped;
+	z_stream _stream;
+	int _zlibErr;
+	uint32 _pos;
+
+	void processData(int flushType) {
+		// This function is called by both write() and finalize().
+		while (_zlibErr == Z_OK && (_stream.avail_in || flushType == Z_FINISH)) {
+			if (_stream.avail_out == 0) {
+				if (_wrapped->write(_buf, BUFSIZE) != BUFSIZE) {
+					_zlibErr = Z_ERRNO;
+					break;
+				}
+				_stream.next_out = _buf;
+				_stream.avail_out = BUFSIZE;
+			}
+			_zlibErr = deflate(&_stream, flushType);
+		}
+	}
+
+public:
+	GZipWriteStream(WriteStream *w) : _wrapped(w), _stream(), _pos(0) {
+		assert(w != nullptr);
+
+		// Adding 16 to windowBits indicates to zlib that it is supposed to
+		// write gzip headers. This feature was added in zlib 1.2.0.4,
+		// released 10 August 2003.
+		// Note: This is *crucial* for savegame compatibility, do *not* remove!
+		_zlibErr = deflateInit2(&_stream,
+		                 Z_DEFAULT_COMPRESSION,
+		                 Z_DEFLATED,
+		                 MAX_WBITS + 16,
+		                 8,
+				 Z_DEFAULT_STRATEGY);
+		assert(_zlibErr == Z_OK);
+
+		_stream.next_out = _buf;
+		_stream.avail_out = BUFSIZE;
+		_stream.avail_in = 0;
+		_stream.next_in = nullptr;
+	}
+
+	~GZipWriteStream() {
+		finalize();
+		deflateEnd(&_stream);
+	}
+
+	bool err() const override {
+		// CHECKME: does Z_STREAM_END make sense here?
+		return (_zlibErr != Z_OK && _zlibErr != Z_STREAM_END) || _wrapped->err();
+	}
+
+	void clearErr() override {
+		// Note: we don't reset the _zlibErr here, as it is not
+		// clear in general how
+		_wrapped->clearErr();
+	}
+
+	void finalize() override {
+		if (_zlibErr != Z_OK)
+			return;
+
+		// Process whatever remaining data there is.
+		processData(Z_FINISH);
+
+		// Since processData only writes out blocks of size BUFSIZE,
+		// we may have to flush some stragglers.
+		uint remainder = BUFSIZE - _stream.avail_out;
+		if (remainder > 0) {
+			if (_wrapped->write(_buf, remainder) != remainder) {
+				_zlibErr = Z_ERRNO;
+			}
+		}
+
+		// Finalize the wrapped savefile, too
+		_wrapped->finalize();
+	}
+
+	uint32 write(const void *dataPtr, uint32 dataSize) override {
+		if (err())
+			return 0;
+
+		// Hook in the new data ...
+		// Note: We need to make a const_cast here, as zlib is not aware
+		// of the const keyword.
+		_stream.next_in = const_cast<byte *>((const byte *)dataPtr);
+		_stream.avail_in = dataSize;
+
+		// ... and flush it to disk
+		processData(Z_NO_FLUSH);
+
+		_pos += dataSize - _stream.avail_in;
+		return dataSize - _stream.avail_in;
+	}
+
+	int64 pos() const override { return _pos; }
+};
+
+SeekableReadStream *wrapCompressedReadStream(SeekableReadStream *toBeWrapped, DisposeAfterUse::Flag disposeParent, uint64 knownSize) {
+	if (!toBeWrapped) {
+		return nullptr;
+	}
+
+	if (toBeWrapped->eos() || toBeWrapped->err() || toBeWrapped->size() < 2) {
+		if (disposeParent == DisposeAfterUse::YES) {
+			delete toBeWrapped;
+		}
+		return nullptr;
+	}
+
+	uint16 header = toBeWrapped->readUint16BE();
+	bool isCompressed = (header == 0x1F8B ||
+			     ((header & 0x0F00) == 0x0800 &&
+			      header % 31 == 0));
+	toBeWrapped->seek(-2, SEEK_CUR);
+	if (isCompressed) {
+		return new GZipReadStream(toBeWrapped, disposeParent, knownSize);
+	}
+	return toBeWrapped;
+}
+
+SeekableReadStream *wrapDeflateReadStream(SeekableReadStream *toBeWrapped, DisposeAfterUse::Flag disposeParent, uint64 knownSize, const byte *dict, uint dictLen) {
+	if (!toBeWrapped) {
+		return nullptr;
+	}
+
+	if (toBeWrapped->eos() || toBeWrapped->err()) {
+		if (disposeParent == DisposeAfterUse::YES) {
+			delete toBeWrapped;
+		}
+		return nullptr;
+	}
+	return new GZipReadStream(toBeWrapped, disposeParent, knownSize, dict, dictLen);
+}
+
+WriteStream *wrapCompressedWriteStream(WriteStream *toBeWrapped) {
+	if (!toBeWrapped)
+		return nullptr;
+	return new GZipWriteStream(toBeWrapped);
+}
+
+} // End of namespace Common