rockbox/rbutil/rbutilqt/zip/unzip.cpp

/****************************************************************************
** Filename: unzip.cpp
** Last updated [dd/mm/yyyy]: 28/01/2007
**
** pkzip 2.0 decompression.
**
** Some of the code has been inspired by other open source projects,
** (mainly Info-Zip and Gilles Vollant's minizip).
** Compression and decompression actually uses the zlib library.
**
** Copyright (C) 2007 Angius Fabrizio. All rights reserved.
**
** This file is part of the OSDaB project (http://osdab.sourceforge.net/).
**
** This file may be distributed and/or modified under the terms of the
** GNU General Public License version 2 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
** See the file LICENSE.GPL that came with this software distribution or
** visit http://www.gnu.org/copyleft/gpl.html for GPL licensing information.
**
**********************************************************************/

#include "unzip.h"
#include "unzip_p.h"
#include "zipentry_p.h"

#include <QString>
#include <QStringList>
#include <QDir>
#include <QFile>
#include <QCoreApplication>

// You can remove this #include if you replace the qDebug() statements.
#include <QtDebug>

/*!
	\class UnZip unzip.h

	\brief PKZip 2.0 file decompression.
	Compatibility with later versions is not ensured as they may use
	unsupported compression algorithms.
	Versions after 2.7 may have an incompatible header format and thus be
	completely incompatible.
*/

/*! \enum UnZip::ErrorCode The result of a decompression operation.
	\value UnZip::Ok No error occurred.
	\value UnZip::ZlibInit Failed to init or load the zlib library.
	\value UnZip::ZlibError The zlib library returned some error.
	\value UnZip::OpenFailed Unable to create or open a device.
	\value UnZip::PartiallyCorrupted Corrupted zip archive - some files could be extracted.
	\value UnZip::Corrupted Corrupted or invalid zip archive.
	\value UnZip::WrongPassword Unable to decrypt a password protected file.
	\value UnZip::NoOpenArchive No archive has been opened yet.
	\value UnZip::FileNotFound Unable to find the requested file in the archive.
	\value UnZip::ReadFailed Reading of a file failed.
	\value UnZip::WriteFailed Writing of a file failed.
	\value UnZip::SeekFailed Seek failed.
	\value UnZip::CreateDirFailed Could not create a directory.
	\value UnZip::InvalidDevice A null device has been passed as parameter.
	\value UnZip::InvalidArchive This is not a valid (or supported) ZIP archive.
	\value UnZip::HeaderConsistencyError Local header record info does not match with the central directory record info. The archive may be corrupted.

	\value UnZip::Skip Internal use only.
	\value UnZip::SkipAll Internal use only.
*/

/*! \enum UnZip::ExtractionOptions Some options for the file extraction methods.
	\value UnZip::ExtractPaths Default. Does not ignore the path of the zipped files.
	\value UnZip::SkipPaths Default. Ignores the path of the zipped files and extracts them all to the same root directory.
*/

//! Local header size (excluding signature, excluding variable length fields)
#define UNZIP_LOCAL_HEADER_SIZE 26
//! Central Directory file entry size (excluding signature, excluding variable length fields)
#define UNZIP_CD_ENTRY_SIZE_NS 42
//! Data descriptor size (excluding signature)
#define UNZIP_DD_SIZE 12
//! End Of Central Directory size (including signature, excluding variable length fields)
#define UNZIP_EOCD_SIZE 22
//! Local header entry encryption header size
#define UNZIP_LOCAL_ENC_HEADER_SIZE 12

// Some offsets inside a CD record (excluding signature)
#define UNZIP_CD_OFF_VERSION 0
#define UNZIP_CD_OFF_GPFLAG 4
#define UNZIP_CD_OFF_CMETHOD 6
#define UNZIP_CD_OFF_MODT 8
#define UNZIP_CD_OFF_MODD 10
#define UNZIP_CD_OFF_CRC32 12
#define UNZIP_CD_OFF_CSIZE 16
#define UNZIP_CD_OFF_USIZE 20
#define UNZIP_CD_OFF_NAMELEN 24
#define UNZIP_CD_OFF_XLEN 26
#define UNZIP_CD_OFF_COMMLEN 28
#define UNZIP_CD_OFF_LHOFFSET 38

// Some offsets inside a local header record (excluding signature)
#define UNZIP_LH_OFF_VERSION 0
#define UNZIP_LH_OFF_GPFLAG 2
#define UNZIP_LH_OFF_CMETHOD 4
#define UNZIP_LH_OFF_MODT 6
#define UNZIP_LH_OFF_MODD 8
#define UNZIP_LH_OFF_CRC32 10
#define UNZIP_LH_OFF_CSIZE 14
#define UNZIP_LH_OFF_USIZE 18
#define UNZIP_LH_OFF_NAMELEN 22
#define UNZIP_LH_OFF_XLEN 24

// Some offsets inside a data descriptor record (excluding signature)
#define UNZIP_DD_OFF_CRC32 0
#define UNZIP_DD_OFF_CSIZE 4
#define UNZIP_DD_OFF_USIZE 8

// Some offsets inside a EOCD record
#define UNZIP_EOCD_OFF_ENTRIES 6
#define UNZIP_EOCD_OFF_CDOFF 12
#define UNZIP_EOCD_OFF_COMMLEN 16

/*!
	Max version handled by this API.
	0x1B = 2.7 --> full compatibility only up to version 2.0 (0x14)
	versions from 2.1 to 2.7 may use unsupported compression methods
	versions after 2.7 may have an incompatible header format
*/
#define UNZIP_VERSION 0x1B
//! Full compatibility granted until this version
#define UNZIP_VERSION_STRICT 0x14

//! CRC32 routine
#define CRC32(c, b) crcTable[((int)c^b) & 0xff] ^ (c >> 8)

//! Checks if some file has been already extracted.
#define UNZIP_CHECK_FOR_VALID_DATA \
	{\
		if (headers != 0)\
		{\
			qDebug() << "Corrupted zip archive. Some files might be extracted.";\
			ec = headers->size() != 0 ? UnZip::PartiallyCorrupted : UnZip::Corrupted;\
			break;\
		}\
		else\
		{\
			delete device;\
			device = 0;\
			qDebug() << "Corrupted or invalid zip archive";\
			ec = UnZip::Corrupted;\
			break;\
		}\
	}


/************************************************************************
 Public interface
*************************************************************************/

/*!
	Creates a new Zip file decompressor.
*/
UnZip::UnZip()
{
	d = new UnzipPrivate;
}

/*!
	Closes any open archive and releases used resources.
*/
UnZip::~UnZip()
{
	closeArchive();
	delete d;
}

/*!
	Returns true if there is an open archive.
*/
bool UnZip::isOpen() const
{
	return d->device != 0;
}

/*!
	Opens a zip archive and reads the files list. Closes any previously opened archive.
*/
UnZip::ErrorCode UnZip::openArchive(const QString& filename)
{
	QFile* file = new QFile(filename);

	if (!file->exists()) {
		delete file;
		return UnZip::FileNotFound;
	}

	if (!file->open(QIODevice::ReadOnly)) {
		delete file;
		return UnZip::OpenFailed;
	}

	return openArchive(file);
}

/*!
	Opens a zip archive and reads the entries list.
	Closes any previously opened archive.
	\warning The class takes ownership of the device so don't delete it!
*/
UnZip::ErrorCode UnZip::openArchive(QIODevice* device)
{
	if (device == 0)
	{
		qDebug() << "Invalid device.";
		return UnZip::InvalidDevice;
	}

	return d->openArchive(device);
}

/*!
	Closes the archive and releases all the used resources (like cached passwords).
*/
void UnZip::closeArchive()
{
	d->closeArchive();
}

QString UnZip::archiveComment() const
{
	if (d->device == 0)
		return QString();
	return d->comment;
}

/*!
	Returns a locale translated error string for a given error code.
*/
QString UnZip::formatError(UnZip::ErrorCode c) const
{
	switch (c)
	{
	case Ok: return QCoreApplication::translate("UnZip", "ZIP operation completed successfully."); break;
	case ZlibInit: return QCoreApplication::translate("UnZip", "Failed to initialize or load zlib library."); break;
	case ZlibError: return QCoreApplication::translate("UnZip", "zlib library error."); break;
	case OpenFailed: return QCoreApplication::translate("UnZip", "Unable to create or open file."); break;
	case PartiallyCorrupted: return QCoreApplication::translate("UnZip", "Partially corrupted archive. Some files might be extracted."); break;
	case Corrupted: return QCoreApplication::translate("UnZip", "Corrupted archive."); break;
	case WrongPassword: return QCoreApplication::translate("UnZip", "Wrong password."); break;
	case NoOpenArchive: return QCoreApplication::translate("UnZip", "No archive has been created yet."); break;
	case FileNotFound: return QCoreApplication::translate("UnZip", "File or directory does not exist."); break;
	case ReadFailed: return QCoreApplication::translate("UnZip", "File read error."); break;
	case WriteFailed: return QCoreApplication::translate("UnZip", "File write error."); break;
	case SeekFailed: return QCoreApplication::translate("UnZip", "File seek error."); break;
	case CreateDirFailed: return QCoreApplication::translate("UnZip", "Unable to create a directory."); break;
	case InvalidDevice: return QCoreApplication::translate("UnZip", "Invalid device."); break;
	case InvalidArchive: return QCoreApplication::translate("UnZip", "Invalid or incompatible zip archive."); break;
	case HeaderConsistencyError: return QCoreApplication::translate("UnZip", "Inconsistent headers. Archive might be corrupted."); break;
	default: ;
	}

	return QCoreApplication::translate("UnZip", "Unknown error.");
}

/*!
	Returns true if the archive contains a file with the given path and name.
*/
bool UnZip::contains(const QString& file) const
{
	if (d->headers == 0)
		return false;

	return d->headers->contains(file);
}

/*!
	Returns complete paths of files and directories in this archive.
*/
QStringList UnZip::fileList() const
{
	return d->headers == 0 ? QStringList() : d->headers->keys();
}

/*!
	Returns information for each (correctly parsed) entry of this archive.
*/
QList<UnZip::ZipEntry> UnZip::entryList() const
{
	QList<UnZip::ZipEntry> list;

	if (d->headers != 0)
	{
		for (QMap<QString,ZipEntryP*>::ConstIterator it = d->headers->constBegin(); it != d->headers->constEnd(); ++it)
		{
			const ZipEntryP* entry = it.value();
			Q_ASSERT(entry != 0);

			ZipEntry z;

			z.filename = it.key();
			if (!entry->comment.isEmpty())
				z.comment = entry->comment;
			z.compressedSize = entry->szComp;
			z.uncompressedSize = entry->szUncomp;
			z.crc32 = entry->crc;
			z.lastModified = d->convertDateTime(entry->modDate, entry->modTime);

			z.compression = entry->compMethod == 0 ? NoCompression : entry->compMethod == 8 ? Deflated : UnknownCompression;
			z.type = z.filename.endsWith("/") ? Directory : File;

			z.encrypted = entry->isEncrypted();

			list.append(z);
		}
	}

	return list;
}

/*!
	Extracts the whole archive to a directory.
*/
UnZip::ErrorCode UnZip::extractAll(const QString& dirname, ExtractionOptions options)
{
	return extractAll(QDir(dirname), options);
}

/*!
	Extracts the whole archive to a directory.
*/
UnZip::ErrorCode UnZip::extractAll(const QDir& dir, ExtractionOptions options)
{
	// this should only happen if we didn't call openArchive() yet
	if (d->device == 0)
		return NoOpenArchive;

	if (d->headers == 0)
		return Ok;

	bool end = false;
	for (QMap<QString,ZipEntryP*>::Iterator itr = d->headers->begin(); itr != d->headers->end(); ++itr)
	{
		ZipEntryP* entry = itr.value();
		Q_ASSERT(entry != 0);

		if ((entry->isEncrypted()) && d->skipAllEncrypted)
			continue;

		switch (d->extractFile(itr.key(), *entry, dir, options))
		{
		case Corrupted:
			qDebug() << "Removing corrupted entry" << itr.key();
			d->headers->erase(itr++);
			if (itr == d->headers->end())
				end = true;
			break;
		case CreateDirFailed:
			break;
		case Skip:
			break;
		case SkipAll:
			d->skipAllEncrypted = true;
			break;
		default:
			;
		}

		if (end)
			break;
	}

	return Ok;
}

/*!
	Extracts a single file to a directory.
*/
UnZip::ErrorCode UnZip::extractFile(const QString& filename, const QString& dirname, ExtractionOptions options)
{
	return extractFile(filename, QDir(dirname), options);
}

/*!
	Extracts a single file to a directory.
*/
UnZip::ErrorCode UnZip::extractFile(const QString& filename, const QDir& dir, ExtractionOptions options)
{
	QMap<QString,ZipEntryP*>::Iterator itr = d->headers->find(filename);
	if (itr != d->headers->end())
	{
		ZipEntryP* entry = itr.value();
		Q_ASSERT(entry != 0);
		return d->extractFile(itr.key(), *entry, dir, options);
	}

	return FileNotFound;
}

/*!
	Extracts a single file to a directory.
*/
UnZip::ErrorCode UnZip::extractFile(const QString& filename, QIODevice* dev, ExtractionOptions options)
{
	if (dev == 0)
		return InvalidDevice;

	QMap<QString,ZipEntryP*>::Iterator itr = d->headers->find(filename);
	if (itr != d->headers->end()) {
		ZipEntryP* entry = itr.value();
		Q_ASSERT(entry != 0);
		return d->extractFile(itr.key(), *entry, dev, options);
	}

	return FileNotFound;
}

/*!
	Extracts a list of files.
	Stops extraction at the first error (but continues if a file does not exist in the archive).
 */
UnZip::ErrorCode UnZip::extractFiles(const QStringList& filenames, const QString& dirname, ExtractionOptions options)
{
	QDir dir(dirname);
	ErrorCode ec;

	for (QStringList::ConstIterator itr = filenames.constBegin(); itr != filenames.constEnd(); ++itr)
	{
		ec = extractFile(*itr, dir, options);
		if (ec == FileNotFound)
			continue;
		if (ec != Ok)
			return ec;
	}

	return Ok;
}

/*!
	Extracts a list of files.
	Stops extraction at the first error (but continues if a file does not exist in the archive).
 */
UnZip::ErrorCode UnZip::extractFiles(const QStringList& filenames, const QDir& dir, ExtractionOptions options)
{
	ErrorCode ec;

	for (QStringList::ConstIterator itr = filenames.constBegin(); itr != filenames.constEnd(); ++itr)
	{
		ec = extractFile(*itr, dir, options);
		if (ec == FileNotFound)
			continue;
		if (ec != Ok)
			return ec;
	}

	return Ok;
}

/*!
	Remove/replace this method to add your own password retrieval routine.
*/
void UnZip::setPassword(const QString& pwd)
{
	d->password = pwd;
}

/*!
	ZipEntry constructor - initialize data. Type is set to File.
*/
UnZip::ZipEntry::ZipEntry()
{
	compressedSize = uncompressedSize = crc32 = 0;
	compression = NoCompression;
	type = File;
	encrypted = false;
}


/************************************************************************
 Private interface
*************************************************************************/

//! \internal
UnzipPrivate::UnzipPrivate()
{
	skipAllEncrypted = false;
	headers = 0;
	device = 0;

	uBuffer = (unsigned char*) buffer1;
	crcTable = (quint32*) get_crc_table();

	cdOffset = eocdOffset = 0;
	cdEntryCount = 0;
	unsupportedEntryCount = 0;
}

//! \internal Parses a Zip archive.
UnZip::ErrorCode UnzipPrivate::openArchive(QIODevice* dev)
{
	Q_ASSERT(dev != 0);

	if (device != 0)
		closeArchive();

	device = dev;

	if (!(device->isOpen() || device->open(QIODevice::ReadOnly)))
	{
		delete device;
		device = 0;

		qDebug() << "Unable to open device for reading";
		return UnZip::OpenFailed;
	}

	UnZip::ErrorCode ec;

	ec = seekToCentralDirectory();
	if (ec != UnZip::Ok)
	{
		closeArchive();
		return ec;
	}

	//! \todo Ignore CD entry count? CD may be corrupted.
	if (cdEntryCount == 0)
	{
		return UnZip::Ok;
	}

	bool continueParsing = true;

	while (continueParsing)
	{
		if (device->read(buffer1, 4) != 4)
			UNZIP_CHECK_FOR_VALID_DATA

		if (! (buffer1[0] == 'P' && buffer1[1] == 'K' && buffer1[2] == 0x01  && buffer1[3] == 0x02) )
			break;

		if ( (ec = parseCentralDirectoryRecord()) != UnZip::Ok )
			break;
	}

	if (ec != UnZip::Ok)
		closeArchive();

	return ec;
}

/*
	\internal Parses a local header record and makes some consistency check
	with the information stored in the Central Directory record for this entry
	that has been previously parsed.
	\todo Optional consistency check (as a ExtractionOptions flag)

	local file header signature     4 bytes  (0x04034b50)
	version needed to extract       2 bytes
	general purpose bit flag        2 bytes
	compression method              2 bytes
	last mod file time              2 bytes
	last mod file date              2 bytes
	crc-32                          4 bytes
	compressed size                 4 bytes
	uncompressed size               4 bytes
	file name length                2 bytes
	extra field length              2 bytes

	file name (variable size)
	extra field (variable size)
*/
UnZip::ErrorCode UnzipPrivate::parseLocalHeaderRecord(const QString& path, ZipEntryP& entry)
{
	if (!device->seek(entry.lhOffset))
		return UnZip::SeekFailed;

	// Test signature
	if (device->read(buffer1, 4) != 4)
		return UnZip::ReadFailed;

	if ((buffer1[0] != 'P') || (buffer1[1] != 'K') || (buffer1[2] != 0x03) || (buffer1[3] != 0x04))
		return UnZip::InvalidArchive;

	if (device->read(buffer1, UNZIP_LOCAL_HEADER_SIZE) != UNZIP_LOCAL_HEADER_SIZE)
		return UnZip::ReadFailed;

	/*
		Check 3rd general purpose bit flag.

		"bit 3: If this bit is set, the fields crc-32, compressed size
		and uncompressed size are set to zero in the local
		header.  The correct values are put in the data descriptor
		immediately following the compressed data."
	*/
	bool hasDataDescriptor = entry.hasDataDescriptor();

	bool checkFailed = false;

	if (!checkFailed)
		checkFailed = entry.compMethod != getUShort(uBuffer, UNZIP_LH_OFF_CMETHOD);
	if (!checkFailed)
		checkFailed = entry.gpFlag[0] != uBuffer[UNZIP_LH_OFF_GPFLAG];
	if (!checkFailed)
		checkFailed = entry.gpFlag[1] != uBuffer[UNZIP_LH_OFF_GPFLAG + 1];
	if (!checkFailed)
		checkFailed = entry.modTime[0] != uBuffer[UNZIP_LH_OFF_MODT];
	if (!checkFailed)
		checkFailed = entry.modTime[1] != uBuffer[UNZIP_LH_OFF_MODT + 1];
	if (!checkFailed)
		checkFailed = entry.modDate[0] != uBuffer[UNZIP_LH_OFF_MODD];
	if (!checkFailed)
		checkFailed = entry.modDate[1] != uBuffer[UNZIP_LH_OFF_MODD + 1];
	if (!hasDataDescriptor)
	{
		if (!checkFailed)
			checkFailed = entry.crc != getULong(uBuffer, UNZIP_LH_OFF_CRC32);
		if (!checkFailed)
			checkFailed = entry.szComp != getULong(uBuffer, UNZIP_LH_OFF_CSIZE);
		if (!checkFailed)
			checkFailed = entry.szUncomp != getULong(uBuffer, UNZIP_LH_OFF_USIZE);
	}

	if (checkFailed)
		return UnZip::HeaderConsistencyError;

	// Check filename
	quint16 szName = getUShort(uBuffer, UNZIP_LH_OFF_NAMELEN);
	if (szName == 0)
		return UnZip::HeaderConsistencyError;

	if (device->read(buffer2, szName) != szName)
		return UnZip::ReadFailed;

	QString filename = QString::fromAscii(buffer2, szName);
	if (filename != path)
	{
		qDebug() << "Filename in local header mismatches.";
		return UnZip::HeaderConsistencyError;
	}

	// Skip extra field
	quint16 szExtra = getUShort(uBuffer, UNZIP_LH_OFF_XLEN);
	if (szExtra != 0)
	{
		if (!device->seek(device->pos() + szExtra))
			return UnZip::SeekFailed;
	}

	entry.dataOffset = device->pos();

	if (hasDataDescriptor)
	{
		/*
			The data descriptor has this OPTIONAL signature: PK\7\8
			We try to skip the compressed data relying on the size set in the
			Central Directory record.
		*/
		if (!device->seek(device->pos() + entry.szComp))
			return UnZip::SeekFailed;

		// Read 4 bytes and check if there is a data descriptor signature
		if (device->read(buffer2, 4) != 4)
			return UnZip::ReadFailed;

		bool hasSignature = buffer2[0] == 'P' && buffer2[1] == 'K' && buffer2[2] == 0x07 && buffer2[3] == 0x08;
		if (hasSignature)
		{
			if (device->read(buffer2, UNZIP_DD_SIZE) != UNZIP_DD_SIZE)
				return UnZip::ReadFailed;
		}
		else
		{
			if (device->read(buffer2 + 4, UNZIP_DD_SIZE - 4) != UNZIP_DD_SIZE - 4)
				return UnZip::ReadFailed;
		}

		// DD: crc, compressed size, uncompressed size
		if (
			entry.crc != getULong((unsigned char*)buffer2, UNZIP_DD_OFF_CRC32) ||
			entry.szComp != getULong((unsigned char*)buffer2, UNZIP_DD_OFF_CSIZE) ||
			entry.szUncomp != getULong((unsigned char*)buffer2, UNZIP_DD_OFF_USIZE)
			)
			return UnZip::HeaderConsistencyError;
	}

	return UnZip::Ok;
}

/*! \internal Attempts to find the start of the central directory record.

	We seek the file back until we reach the "End Of Central Directory"
	signature PK\5\6.

	end of central dir signature    4 bytes  (0x06054b50)
	number of this disk             2 bytes
	number of the disk with the
	start of the central directory  2 bytes
	total number of entries in the
	central directory on this disk  2 bytes
	total number of entries in
	the central directory           2 bytes
	size of the central directory   4 bytes
	offset of start of central
	directory with respect to
	the starting disk number        4 bytes
	.ZIP file comment length        2 bytes
	--- SIZE UNTIL HERE: UNZIP_EOCD_SIZE ---
	.ZIP file comment       (variable size)
*/
UnZip::ErrorCode UnzipPrivate::seekToCentralDirectory()
{
	qint64 length = device->size();
	qint64 offset = length - UNZIP_EOCD_SIZE;

	if (length < UNZIP_EOCD_SIZE)
		return UnZip::InvalidArchive;

	if (!device->seek( offset ))
		return UnZip::SeekFailed;

	if (device->read(buffer1, UNZIP_EOCD_SIZE) != UNZIP_EOCD_SIZE)
		return UnZip::ReadFailed;

	bool eocdFound = (buffer1[0] == 'P' && buffer1[1] == 'K' && buffer1[2] == 0x05 && buffer1[3] == 0x06);

	if (eocdFound)
	{
		// Zip file has no comment (the only variable length field in the EOCD record)
		eocdOffset = offset;
	}
	else
	{
		qint64 read;
		char* p = 0;

		offset -= UNZIP_EOCD_SIZE;

		if (offset <= 0)
			return UnZip::InvalidArchive;

		if (!device->seek( offset ))
			return UnZip::SeekFailed;

		while ((read = device->read(buffer1, UNZIP_EOCD_SIZE)) >= 0)
		{
			if ( (p = strstr(buffer1, "PK\5\6")) != 0)
			{
				// Seek to the start of the EOCD record so we can read it fully
				// Yes... we could simply read the missing bytes and append them to the buffer
				// but this is far easier so heck it!
				device->seek( offset + (p - buffer1) );
				eocdFound = true;
				eocdOffset = offset + (p - buffer1);

				// Read EOCD record
				if (device->read(buffer1, UNZIP_EOCD_SIZE) != UNZIP_EOCD_SIZE)
					return UnZip::ReadFailed;

				break;
			}

			offset -= UNZIP_EOCD_SIZE;
			if (offset <= 0)
				return UnZip::InvalidArchive;

			if (!device->seek( offset ))
				return UnZip::SeekFailed;
		}
	}

	if (!eocdFound)
		return UnZip::InvalidArchive;

	// Parse EOCD to locate CD offset
	offset = getULong((const unsigned char*)buffer1, UNZIP_EOCD_OFF_CDOFF + 4);

	cdOffset = offset;

	cdEntryCount = getUShort((const unsigned char*)buffer1, UNZIP_EOCD_OFF_ENTRIES + 4);

	quint16 commentLength = getUShort((const unsigned char*)buffer1, UNZIP_EOCD_OFF_COMMLEN + 4);
	if (commentLength != 0)
	{
		QByteArray c = device->read(commentLength);
		if (c.count() != commentLength)
			return UnZip::ReadFailed;

		comment = c;
	}

	// Seek to the start of the CD record
	if (!device->seek( cdOffset ))
		return UnZip::SeekFailed;

	return UnZip::Ok;
}

/*!
	\internal Parses a central directory record.

	Central Directory record structure:

	[file header 1]
	.
	.
	.
	[file header n]
	[digital signature] // PKZip 6.2 or later only

	File header:

	central file header signature   4 bytes  (0x02014b50)
	version made by                 2 bytes
	version needed to extract       2 bytes
	general purpose bit flag        2 bytes
	compression method              2 bytes
	last mod file time              2 bytes
	last mod file date              2 bytes
	crc-32                          4 bytes
	compressed size                 4 bytes
	uncompressed size               4 bytes
	file name length                2 bytes
	extra field length              2 bytes
	file comment length             2 bytes
	disk number start               2 bytes
	internal file attributes        2 bytes
	external file attributes        4 bytes
	relative offset of local header 4 bytes

	file name (variable size)
	extra field (variable size)
	file comment (variable size)
*/
UnZip::ErrorCode UnzipPrivate::parseCentralDirectoryRecord()
{
	// Read CD record
	if (device->read(buffer1, UNZIP_CD_ENTRY_SIZE_NS) != UNZIP_CD_ENTRY_SIZE_NS)
		return UnZip::ReadFailed;

	bool skipEntry = false;

	// Get compression type so we can skip non compatible algorithms
	quint16 compMethod = getUShort(uBuffer, UNZIP_CD_OFF_CMETHOD);

	// Get variable size fields length so we can skip the whole record
	// if necessary
	quint16 szName = getUShort(uBuffer, UNZIP_CD_OFF_NAMELEN);
	quint16 szExtra = getUShort(uBuffer, UNZIP_CD_OFF_XLEN);
	quint16 szComment = getUShort(uBuffer, UNZIP_CD_OFF_COMMLEN);

	quint32 skipLength = szName + szExtra + szComment;

	UnZip::ErrorCode ec = UnZip::Ok;

	if ((compMethod != 0) && (compMethod != 8))
	{
		qDebug() << "Unsupported compression method. Skipping file.";
		skipEntry = true;
	}

	// Header parsing may be a problem if version is bigger than UNZIP_VERSION
	if (!skipEntry && buffer1[UNZIP_CD_OFF_VERSION] > UNZIP_VERSION)
	{
		qDebug() << "Unsupported PKZip version. Skipping file.";
		skipEntry = true;
	}

	if (!skipEntry && szName == 0)
	{
		qDebug() << "Skipping file with no name.";
		skipEntry = true;
	}

	if (!skipEntry && device->read(buffer2, szName) != szName)
	{
		ec = UnZip::ReadFailed;
		skipEntry = true;
	}

	if (skipEntry)
	{
		if (ec == UnZip::Ok)
		{
			if (!device->seek( device->pos() + skipLength ))
				ec = UnZip::SeekFailed;

			unsupportedEntryCount++;
		}

		return ec;
	}

	QString filename = QString::fromAscii(buffer2, szName);

	ZipEntryP* h = new ZipEntryP;
	h->compMethod = compMethod;

	h->gpFlag[0] = buffer1[UNZIP_CD_OFF_GPFLAG];
	h->gpFlag[1] = buffer1[UNZIP_CD_OFF_GPFLAG + 1];

	h->modTime[0] = buffer1[UNZIP_CD_OFF_MODT];
	h->modTime[1] = buffer1[UNZIP_CD_OFF_MODT + 1];

	h->modDate[0] = buffer1[UNZIP_CD_OFF_MODD];
	h->modDate[1] = buffer1[UNZIP_CD_OFF_MODD + 1];

	h->crc = getULong(uBuffer, UNZIP_CD_OFF_CRC32);
	h->szComp = getULong(uBuffer, UNZIP_CD_OFF_CSIZE);
	h->szUncomp = getULong(uBuffer, UNZIP_CD_OFF_USIZE);

	// Skip extra field (if any)
	if (szExtra != 0)
	{
		if (!device->seek( device->pos() + szExtra ))
		{
			delete h;
			return UnZip::SeekFailed;
		}
	}

	// Read comment field (if any)
	if (szComment != 0)
	{
		if (device->read(buffer2, szComment) != szComment)
		{
			delete h;
			return UnZip::ReadFailed;
		}

		h->comment = QString::fromAscii(buffer2, szComment);
	}

	h->lhOffset = getULong(uBuffer, UNZIP_CD_OFF_LHOFFSET);

	if (headers == 0)
		headers = new QMap<QString, ZipEntryP*>();
	headers->insert(filename, h);

	return UnZip::Ok;
}

//! \internal Closes the archive and resets the internal status.
void UnzipPrivate::closeArchive()
{
	if (device == 0)
		return;

	skipAllEncrypted = false;

	if (headers != 0)
	{
		qDeleteAll(*headers);
		delete headers;
		headers = 0;
	}

	delete device; device = 0;

	cdOffset = eocdOffset = 0;
	cdEntryCount = 0;
	unsupportedEntryCount = 0;

	comment.clear();
}

//! \internal
UnZip::ErrorCode UnzipPrivate::extractFile(const QString& path, ZipEntryP& entry, const QDir& dir, UnZip::ExtractionOptions options)
{
	QString name(path);
	QString dirname;
	QString directory;

	int pos = name.lastIndexOf('/');

	// This entry is for a directory
	if (pos == name.length() - 1)
	{
		if (options.testFlag(UnZip::SkipPaths))
			return UnZip::Ok;

		directory = QString("%1/%2").arg(dir.absolutePath()).arg(QDir::cleanPath(name));
		if (!createDirectory(directory))
		{
			qDebug() << QString("Unable to create directory: %1").arg(directory);
			return UnZip::CreateDirFailed;
		}

		return UnZip::Ok;
	}

	// Extract path from entry
	if (pos > 0)
	{
		// get directory part
		dirname = name.left(pos);
		if (options.testFlag(UnZip::SkipPaths))
		{
			directory = dir.absolutePath();
		}
		else
		{
			directory = QString("%1/%2").arg(dir.absolutePath()).arg(QDir::cleanPath(dirname));
			if (!createDirectory(directory))
			{
				qDebug() << QString("Unable to create directory: %1").arg(directory);
				return UnZip::CreateDirFailed;
			}
		}
		name = name.right(name.length() - pos - 1);
	} else directory = dir.absolutePath();

	name = QString("%1/%2").arg(directory).arg(name);

	QFile outFile(name);

	if (!outFile.open(QIODevice::WriteOnly))
	{
		qDebug() << QString("Unable to open %1 for writing").arg(name);
		return UnZip::OpenFailed;
	}

	//! \todo Set creation/last_modified date/time

	UnZip::ErrorCode ec = extractFile(path, entry, &outFile, options);

	outFile.close();

	if (ec != UnZip::Ok)
	{
		if (!outFile.remove())
			qDebug() << QString("Unable to remove corrupted file: %1").arg(name);
	}

	return ec;
}

//! \internal
UnZip::ErrorCode UnzipPrivate::extractFile(const QString& path, ZipEntryP& entry, QIODevice* dev, UnZip::ExtractionOptions options)
{
	Q_UNUSED(options);
	Q_ASSERT(dev != 0);

	if (!entry.lhEntryChecked)
	{
		UnZip::ErrorCode ec = parseLocalHeaderRecord(path, entry);
		entry.lhEntryChecked = true;

		if (ec != UnZip::Ok)
			return ec;
	}

	if (!device->seek(entry.dataOffset))
		return UnZip::SeekFailed;

	// Encryption keys
	quint32 keys[3];

	if (entry.isEncrypted())
	{
		UnZip::ErrorCode e = testPassword(keys, path, entry);
		if (e != UnZip::Ok)
		{
			qDebug() << QString("Unable to decrypt %1").arg(path);
			return e;
		}//! Encryption header size
		entry.szComp -= UNZIP_LOCAL_ENC_HEADER_SIZE; // remove encryption header size
	}

	if (entry.szComp == 0)
	{
		if (entry.crc != 0)
			return UnZip::Corrupted;

		return UnZip::Ok;
	}

	uInt rep = entry.szComp / UNZIP_READ_BUFFER;
	uInt rem = entry.szComp % UNZIP_READ_BUFFER;
	uInt cur = 0;

	// extract data
	qint64 read;
	quint64 tot = 0;

	quint32 myCRC = crc32(0L, Z_NULL, 0);

	if (entry.compMethod == 0)
	{
		while ( (read = device->read(buffer1, cur < rep ? UNZIP_READ_BUFFER : rem)) > 0 )
		{
			if (entry.isEncrypted())
				decryptBytes(keys, buffer1, read);

			myCRC = crc32(myCRC, uBuffer, read);

			if (dev->write(buffer1, read) != read)
				return UnZip::WriteFailed;

			cur++;
			tot += read;

			if (tot == entry.szComp)
				break;
		}

		if (read < 0)
			return UnZip::ReadFailed;
	}
	else if (entry.compMethod == 8)
	{
		/* Allocate inflate state */
		z_stream zstr;
		zstr.zalloc = Z_NULL;
		zstr.zfree = Z_NULL;
		zstr.opaque = Z_NULL;
		zstr.next_in = Z_NULL;
		zstr.avail_in = 0;

		int zret;

		// Use inflateInit2 with negative windowBits to get raw decompression
		if ( (zret = inflateInit2_(&zstr, -MAX_WBITS, ZLIB_VERSION, sizeof(z_stream))) != Z_OK )
			return UnZip::ZlibError;

		int szDecomp;

		// Decompress until deflate stream ends or end of file
		do
		{
			read = device->read(buffer1, cur < rep ? UNZIP_READ_BUFFER : rem);
			if (read == 0)
				break;
			if (read < 0)
			{
				(void)inflateEnd(&zstr);
				return UnZip::ReadFailed;
			}

			if (entry.isEncrypted())
				decryptBytes(keys, buffer1, read);

			cur++;
			tot += read;

			zstr.avail_in = (uInt) read;
			zstr.next_in = (Bytef*) buffer1;


			// Run inflate() on input until output buffer not full
			do {
				zstr.avail_out = UNZIP_READ_BUFFER;
				zstr.next_out = (Bytef*) buffer2;;

				zret = inflate(&zstr, Z_NO_FLUSH);

				switch (zret) {
					case Z_NEED_DICT:
					case Z_DATA_ERROR:
					case Z_MEM_ERROR:
						inflateEnd(&zstr);
						return UnZip::WriteFailed;
					default:
						;
				}

				szDecomp = UNZIP_READ_BUFFER - zstr.avail_out;
				if (dev->write(buffer2, szDecomp) != szDecomp)
				{
					inflateEnd(&zstr);
					return UnZip::ZlibError;
				}

				myCRC = crc32(myCRC, (const Bytef*) buffer2, szDecomp);

			} while (zstr.avail_out == 0);

		}
		while (zret != Z_STREAM_END);

		inflateEnd(&zstr);
	}

	if (myCRC != entry.crc)
		return UnZip::Corrupted;

	return UnZip::Ok;
}

//! \internal Creates a new directory and all the needed parent directories.
bool UnzipPrivate::createDirectory(const QString& path)
{
	QDir d(path);
	if (!d.exists())
	{
		int sep = path.lastIndexOf("/");
		if (sep <= 0) return true;

		if (!createDirectory(path.left(sep)))
			return false;

		if (!d.mkdir(path))
		{
			qDebug() << QString("Unable to create directory: %1").arg(path);
			return false;
		}
	}

	return true;
}

/*!
	\internal Reads an quint32 (4 bytes) from a byte array starting at given offset.
*/
quint32 UnzipPrivate::getULong(const unsigned char* data, quint32 offset) const
{
	quint32 res = (quint32) data[offset];
	res |= (((quint32)data[offset+1]) << 8);
	res |= (((quint32)data[offset+2]) << 16);
	res |= (((quint32)data[offset+3]) << 24);

	return res;
}

/*!
	\internal Reads an quint64 (8 bytes) from a byte array starting at given offset.
*/
quint64 UnzipPrivate::getULLong(const unsigned char* data, quint32 offset) const
{
	quint64 res = (quint64) data[offset];
	res |= (((quint64)data[offset+1]) << 8);
	res |= (((quint64)data[offset+2]) << 16);
	res |= (((quint64)data[offset+3]) << 24);
	res |= (((quint64)data[offset+1]) << 32);
	res |= (((quint64)data[offset+2]) << 40);
	res |= (((quint64)data[offset+3]) << 48);
	res |= (((quint64)data[offset+3]) << 56);

	return res;
}

/*!
	\internal Reads an quint16 (2 bytes) from a byte array starting at given offset.
*/
quint16 UnzipPrivate::getUShort(const unsigned char* data, quint32 offset) const
{
	return (quint16) data[offset] | (((quint16)data[offset+1]) << 8);
}

/*!
	\internal Return the next byte in the pseudo-random sequence
 */
int UnzipPrivate::decryptByte(quint32 key2) const
{
	quint16 temp = ((quint16)(key2) & 0xffff) | 2;
	return (int)(((temp * (temp ^ 1)) >> 8) & 0xff);
}

/*!
	\internal Update the encryption keys with the next byte of plain text
 */
void UnzipPrivate::updateKeys(quint32* keys, int c) const
{
	keys[0] = CRC32(keys[0], c);
	keys[1] += keys[0] & 0xff;
	keys[1] = keys[1] * 134775813L + 1;
	keys[2] = CRC32(keys[2], ((int)keys[1]) >> 24);
}

/*!
	\internal Initialize the encryption keys and the random header according to
	the given password.
 */
void UnzipPrivate::initKeys(const QString& pwd, quint32* keys) const
{
	keys[0] = 305419896L;
	keys[1] = 591751049L;
	keys[2] = 878082192L;

	QByteArray pwdBytes = pwd.toAscii();
	int sz = pwdBytes.size();
	const char* ascii = pwdBytes.data();

	for (int i=0; i<sz; ++i)
		updateKeys(keys, (int)ascii[i]);
}

/*!
	\internal Attempts to test a password without actually extracting a file.
	The \p file parameter can be used in the user interface or for debugging purposes
	as it is the name of the encrypted file for wich the password is being tested.
*/
UnZip::ErrorCode UnzipPrivate::testPassword(quint32* keys, const QString& file, const ZipEntryP& header)
{
	Q_UNUSED(file);

	// read encryption keys
	if (device->read(buffer1, 12) != 12)
		return UnZip::Corrupted;

	// Replace this code if you want to i.e. call some dialog and ask the user for a password
	initKeys(password, keys);
	if (testKeys(header, keys))
		return UnZip::Ok;

	return UnZip::Skip;
}

/*!
	\internal Tests a set of keys on the encryption header.
*/
bool UnzipPrivate::testKeys(const ZipEntryP& header, quint32* keys)
{
	char lastByte;

	// decrypt encryption header
	for (int i=0; i<11; ++i)
		updateKeys(keys, lastByte = buffer1[i] ^ decryptByte(keys[2]));
	updateKeys(keys, lastByte = buffer1[11] ^ decryptByte(keys[2]));

	// if there is an extended header (bit in the gp flag) buffer[11] is a byte from the file time
	// with no extended header we have to check the crc high-order byte
	char c = ((header.gpFlag[0] & 0x08) == 8) ? header.modTime[1] : header.crc >> 24;

	return (lastByte == c);
}

/*!
	\internal Decrypts an array of bytes long \p read.
*/
void UnzipPrivate::decryptBytes(quint32* keys, char* buffer, qint64 read)
{
	for (int i=0; i<(int)read; ++i)
		updateKeys(keys, buffer[i] ^= decryptByte(keys[2]));
}

/*!
	\internal Converts date and time values from ZIP format to a QDateTime object.
*/
QDateTime UnzipPrivate::convertDateTime(const unsigned char date[2], const unsigned char time[2]) const
{
	QDateTime dt;

	// Usual PKZip low-byte to high-byte order

	// Date: 7 bits = years from 1980, 4 bits = month, 5 bits = day
	quint16 year = (date[1] >> 1) & 127;
	quint16 month = ((date[1] << 3) & 14) | ((date[0] >> 5) & 7);
	quint16 day = date[0] & 31;

	// Time: 5 bits hour, 6 bits minutes, 5 bits seconds with a 2sec precision
	quint16 hour = (time[1] >> 3) & 31;
	quint16 minutes = ((time[1] << 3) & 56) | ((time[0] >> 5) & 7);
	quint16 seconds = (time[0] & 31) * 2;

	dt.setDate(QDate(1980 + year, month, day));
	dt.setTime(QTime(hour, minutes, seconds));
	return dt;
}