/// <summary>
/// Gets the offset of an archive that is positioned 0 or more bytes
/// from the start of the Stream.
/// </summary>
/// <param name="stream">A stream for reading the archive.</param>
/// <returns>The offset in bytes of the archive,
/// or -1 if no archive is found in the Stream.</returns>
/// <remarks>The archive must begin on a 4-byte boundary.</remarks>
public override long FindArchiveOffset(Stream stream)
{
if (stream == null)
{
throw new ArgumentNullException("stream");
}
long offset = base.FindArchiveOffset(stream);
if (offset > 0)
{
// Some self-extract packages include the exe stub in file offset calculations.
// Check the first header directory offset to decide whether the entire
// archive needs to be offset or not.
ZipEndOfCentralDirectory eocd = this.GetEOCD(null, stream);
if (eocd != null && eocd.totalEntries > 0)
{
stream.Seek(eocd.dirOffset, SeekOrigin.Begin);
ZipFileHeader header = new ZipFileHeader();
if (header.Read(stream, true) && header.localHeaderOffset < stream.Length)
{
stream.Seek(header.localHeaderOffset, SeekOrigin.Begin);
if (header.Read(stream, false))
{
return(0);
}
}
}
}
return(offset);
}
/// <summary>
/// Creates a zip archive or chain of zip archives.
/// </summary>
/// <param name="streamContext">A context interface to handle opening
/// and closing of archive and file streams.</param>
/// <param name="files">An array of file lists. Each list is
/// compressed into one stream in the archive.</param>
/// <param name="maxArchiveSize">The maximum number of bytes for one archive
/// before the contents are chained to the next archive, or zero for unlimited
/// archive size.</param>
/// <exception cref="ArchiveException">The archive could not be
/// created.</exception>
/// <remarks>
/// The stream context implementation may provide a mapping from the file
/// paths within the archive to the external file paths.
/// </remarks>
public override void Pack(
IPackStreamContext streamContext,
IEnumerable <string> files,
long maxArchiveSize)
{
if (streamContext == null)
{
throw new ArgumentNullException("streamContext");
}
if (files == null)
{
throw new ArgumentNullException("files");
}
lock (this)
{
Stream archiveStream = null;
try
{
this.ResetProgressData();
this.totalArchives = 1;
object forceZip64Value = streamContext.GetOption("forceZip64", null);
bool forceZip64 = Convert.ToBoolean(
forceZip64Value, CultureInfo.InvariantCulture);
// Count the total number of files and bytes to be compressed.
foreach (string file in files)
{
FileAttributes attributes;
DateTime lastWriteTime;
Stream fileStream = streamContext.OpenFileReadStream(
file,
out attributes,
out lastWriteTime);
if (fileStream != null)
{
this.totalFileBytes += fileStream.Length;
this.totalFiles++;
streamContext.CloseFileReadStream(file, fileStream);
}
}
List <ZipFileHeader> fileHeaders = new List <ZipFileHeader>();
this.currentFileNumber = -1;
if (this.currentArchiveName == null)
{
this.mainArchiveName = streamContext.GetArchiveName(0);
this.currentArchiveName = this.mainArchiveName;
if (string.IsNullOrWhiteSpace(this.currentArchiveName))
{
throw new FileNotFoundException("No name provided for archive.");
}
}
this.OnProgress(ArchiveProgressType.StartArchive);
// Compress files one by one, saving header info for each.
foreach (string file in files)
{
ZipFileHeader fileHeader = this.PackOneFile(
streamContext,
file,
maxArchiveSize,
forceZip64,
ref archiveStream);
if (fileHeader != null)
{
fileHeaders.Add(fileHeader);
}
this.currentArchiveTotalBytes = (archiveStream != null ?
archiveStream.Position : 0);
this.currentArchiveBytesProcessed = this.currentArchiveTotalBytes;
}
bool zip64 = forceZip64 || this.totalFiles > UInt16.MaxValue;
// Write the central directory composed of all the file headers.
uint centralDirStartArchiveNumber = 0;
long centralDirStartPosition = 0;
long centralDirSize = 0;
for (int i = 0; i < fileHeaders.Count; i++)
{
ZipFileHeader fileHeader = fileHeaders[i];
int headerSize = fileHeader.GetSize(true);
centralDirSize += headerSize;
this.CheckArchiveWriteStream(
streamContext,
maxArchiveSize,
headerSize,
ref archiveStream);
if (i == 0)
{
centralDirStartArchiveNumber = (uint)this.currentArchiveNumber;
centralDirStartPosition = archiveStream.Position;
}
fileHeader.Write(archiveStream, true);
if (fileHeader.zip64)
{
zip64 = true;
}
}
this.currentArchiveTotalBytes =
(archiveStream != null ? archiveStream.Position : 0);
this.currentArchiveBytesProcessed = this.currentArchiveTotalBytes;
ZipEndOfCentralDirectory eocd = new ZipEndOfCentralDirectory();
eocd.dirStartDiskNumber = centralDirStartArchiveNumber;
eocd.entriesOnDisk = fileHeaders.Count;
eocd.totalEntries = fileHeaders.Count;
eocd.dirSize = centralDirSize;
eocd.dirOffset = centralDirStartPosition;
eocd.comment = this.comment;
Zip64EndOfCentralDirectoryLocator eocdl =
new Zip64EndOfCentralDirectoryLocator();
int maxFooterSize = eocd.GetSize(false);
if (archiveStream != null && (zip64 || archiveStream.Position >
((long)UInt32.MaxValue) - eocd.GetSize(false)))
{
maxFooterSize += eocd.GetSize(true) + (int)
Zip64EndOfCentralDirectoryLocator.EOCDL64_SIZE;
zip64 = true;
}
this.CheckArchiveWriteStream(
streamContext,
maxArchiveSize,
maxFooterSize,
ref archiveStream);
eocd.diskNumber = (uint)this.currentArchiveNumber;
if (zip64)
{
eocd.versionMadeBy = 45;
eocd.versionNeeded = 45;
eocd.zip64 = true;
eocdl.dirOffset = archiveStream.Position;
eocdl.dirStartDiskNumber = (uint)this.currentArchiveNumber;
eocdl.totalDisks = (uint)this.currentArchiveNumber + 1;
eocd.Write(archiveStream);
eocdl.Write(archiveStream);
eocd.dirOffset = UInt32.MaxValue;
eocd.dirStartDiskNumber = UInt16.MaxValue;
}
eocd.zip64 = false;
eocd.Write(archiveStream);
this.currentArchiveTotalBytes = archiveStream.Position;
this.currentArchiveBytesProcessed = this.currentArchiveTotalBytes;
}
finally
{
if (archiveStream != null)
{
streamContext.CloseArchiveWriteStream(
this.currentArchiveNumber, this.mainArchiveName, archiveStream);
this.OnProgress(ArchiveProgressType.FinishArchive);
}
}
}
}
/// <summary>
/// Adds one file to a zip archive in the process of being created.
/// </summary>
private ZipFileHeader PackOneFile(
IPackStreamContext streamContext,
string file,
long maxArchiveSize,
bool forceZip64,
ref Stream archiveStream)
{
Stream fileStream = null;
int headerArchiveNumber = 0;
try
{
// TODO: call GetOption to get compression method for the specific file
ZipCompressionMethod compressionMethod = ZipCompressionMethod.Deflate;
if (this.CompressionLevel == CompressionLevel.None)
{
compressionMethod = ZipCompressionMethod.Store;
}
Func <Stream, Stream> compressionStreamCreator;
if (!ZipEngine.compressionStreamCreators.TryGetValue(
compressionMethod, out compressionStreamCreator))
{
return(null);
}
FileAttributes attributes;
DateTime lastWriteTime;
fileStream = streamContext.OpenFileReadStream(
file, out attributes, out lastWriteTime);
if (fileStream == null)
{
return(null);
}
this.currentFileName = file;
this.currentFileNumber++;
this.currentFileTotalBytes = fileStream.Length;
this.currentFileBytesProcessed = 0;
this.OnProgress(ArchiveProgressType.StartFile);
ZipFileInfo fileInfo = new ZipFileInfo(
file,
this.currentArchiveNumber,
attributes,
lastWriteTime,
fileStream.Length,
0,
compressionMethod);
bool zip64 = forceZip64 || fileStream.Length >= (long)UInt32.MaxValue;
ZipFileHeader fileHeader = new ZipFileHeader(fileInfo, zip64);
this.CheckArchiveWriteStream(
streamContext,
maxArchiveSize,
fileHeader.GetSize(false),
ref archiveStream);
long headerPosition = archiveStream.Position;
fileHeader.Write(archiveStream, false);
headerArchiveNumber = this.currentArchiveNumber;
uint crc;
long bytesWritten = this.PackFileBytes(
streamContext,
fileStream,
maxArchiveSize,
compressionStreamCreator,
ref archiveStream,
out crc);
fileHeader.Update(
bytesWritten,
fileStream.Length,
crc,
headerPosition,
headerArchiveNumber);
streamContext.CloseFileReadStream(file, fileStream);
fileStream = null;
// Go back and rewrite the updated file header.
if (this.currentArchiveNumber == headerArchiveNumber)
{
long fileEndPosition = archiveStream.Position;
archiveStream.Seek(headerPosition, SeekOrigin.Begin);
fileHeader.Write(archiveStream, false);
archiveStream.Seek(fileEndPosition, SeekOrigin.Begin);
}
else
{
// The file spanned archives, so temporarily reopen
// the archive where it started.
string headerArchiveName = streamContext.GetArchiveName(
headerArchiveNumber + 1);
Stream headerStream = null;
try
{
headerStream = streamContext.OpenArchiveWriteStream(
headerArchiveNumber, headerArchiveName, false, this);
headerStream.Seek(headerPosition, SeekOrigin.Begin);
fileHeader.Write(headerStream, false);
}
finally
{
if (headerStream != null)
{
streamContext.CloseArchiveWriteStream(
headerArchiveNumber, headerArchiveName, headerStream);
}
}
}
this.OnProgress(ArchiveProgressType.FinishFile);
return(fileHeader);
}
finally
{
if (fileStream != null)
{
streamContext.CloseFileReadStream(
this.currentFileName, fileStream);
}
}
}
/// <summary>
/// Unpacks a single file from an archive or archive chain.
/// </summary>
private void UnpackOneFile(
IUnpackStreamContext streamContext,
ZipFileHeader header,
ref Stream archiveStream)
{
ZipFileInfo fileInfo = null;
Stream fileStream = null;
try
{
Func <Stream, Stream> compressionStreamCreator;
if (!ZipEngine.decompressionStreamCreators.TryGetValue(
header.compressionMethod, out compressionStreamCreator))
{
// Silently skip files of an unsupported compression method.
return;
}
long compressedSize;
long uncompressedSize;
long localHeaderOffset;
int archiveNumber;
uint crc;
header.GetZip64Fields(
out compressedSize,
out uncompressedSize,
out localHeaderOffset,
out archiveNumber,
out crc);
if (this.currentArchiveNumber != archiveNumber + 1)
{
if (archiveStream != null)
{
streamContext.CloseArchiveReadStream(
this.currentArchiveNumber,
String.Empty,
archiveStream);
archiveStream = null;
this.OnProgress(ArchiveProgressType.FinishArchive);
this.currentArchiveName = null;
}
this.currentArchiveNumber = (short)(archiveNumber + 1);
this.currentArchiveBytesProcessed = 0;
this.currentArchiveTotalBytes = 0;
archiveStream = this.OpenArchive(
streamContext, this.currentArchiveNumber);
FileStream archiveFileStream = archiveStream as FileStream;
this.currentArchiveName = (archiveFileStream != null ?
Path.GetFileName(archiveFileStream.Name) : null);
this.currentArchiveTotalBytes = archiveStream.Length;
this.currentArchiveNumber--;
this.OnProgress(ArchiveProgressType.StartArchive);
this.currentArchiveNumber++;
}
archiveStream.Seek(localHeaderOffset, SeekOrigin.Begin);
ZipFileHeader localHeader = new ZipFileHeader();
if (!localHeader.Read(archiveStream, false) ||
!ZipEngine.AreFilePathsEqual(localHeader.fileName, header.fileName))
{
string msg = "Could not read file: " + header.fileName;
throw new ZipException(msg);
}
fileInfo = header.ToZipFileInfo();
fileStream = streamContext.OpenFileWriteStream(
fileInfo.FullName,
fileInfo.Length,
fileInfo.LastWriteTime);
if (fileStream != null)
{
this.currentFileName = header.fileName;
this.currentFileBytesProcessed = 0;
this.currentFileTotalBytes = fileInfo.Length;
this.currentArchiveNumber--;
this.OnProgress(ArchiveProgressType.StartFile);
this.currentArchiveNumber++;
this.UnpackFileBytes(
streamContext,
fileInfo.FullName,
fileInfo.CompressedLength,
fileInfo.Length,
header.crc32,
fileStream,
compressionStreamCreator,
ref archiveStream);
}
}
finally
{
if (fileStream != null)
{
streamContext.CloseFileWriteStream(
fileInfo.FullName,
fileStream,
fileInfo.Attributes,
fileInfo.LastWriteTime);
this.currentArchiveNumber--;
this.OnProgress(ArchiveProgressType.FinishFile);
this.currentArchiveNumber++;
}
}
}
/// <summary>
/// Reads all the file headers from the central directory in the main archive.
/// </summary>
private IList <ZipFileHeader> GetCentralDirectory(IUnpackStreamContext streamContext)
{
Stream archiveStream = null;
this.currentArchiveNumber = 0;
try
{
List <ZipFileHeader> headers = new List <ZipFileHeader>();
archiveStream = this.OpenArchive(streamContext, 0);
ZipEndOfCentralDirectory eocd = this.GetEOCD(streamContext, archiveStream);
if (eocd == null)
{
return(null);
}
else if (eocd.totalEntries == 0)
{
return(headers);
}
headers.Capacity = (int)eocd.totalEntries;
if (eocd.dirOffset > archiveStream.Length - ZipFileHeader.CFH_FIXEDSIZE)
{
streamContext.CloseArchiveReadStream(
this.currentArchiveNumber, String.Empty, archiveStream);
archiveStream = null;
}
else
{
archiveStream.Seek(eocd.dirOffset, SeekOrigin.Begin);
uint sig = new BinaryReader(archiveStream).ReadUInt32();
if (sig != ZipFileHeader.CFHSIG)
{
streamContext.CloseArchiveReadStream(
this.currentArchiveNumber, String.Empty, archiveStream);
archiveStream = null;
}
}
if (archiveStream == null)
{
this.currentArchiveNumber = (short)(eocd.dirStartDiskNumber + 1);
archiveStream = streamContext.OpenArchiveReadStream(
this.currentArchiveNumber, String.Empty, this);
if (archiveStream == null)
{
return(null);
}
}
archiveStream.Seek(eocd.dirOffset, SeekOrigin.Begin);
while (headers.Count < eocd.totalEntries)
{
ZipFileHeader header = new ZipFileHeader();
if (!header.Read(archiveStream, true))
{
throw new ZipException(
"Missing or invalid central directory file header");
}
headers.Add(header);
if (headers.Count < eocd.totalEntries &&
archiveStream.Position == archiveStream.Length)
{
streamContext.CloseArchiveReadStream(
this.currentArchiveNumber, String.Empty, archiveStream);
this.currentArchiveNumber++;
archiveStream = streamContext.OpenArchiveReadStream(
this.currentArchiveNumber, String.Empty, this);
if (archiveStream == null)
{
this.currentArchiveNumber = 0;
archiveStream = streamContext.OpenArchiveReadStream(
this.currentArchiveNumber, String.Empty, this);
}
}
}
return(headers);
}
finally
{
if (archiveStream != null)
{
streamContext.CloseArchiveReadStream(
this.currentArchiveNumber, String.Empty, archiveStream);
}
}
}
/// <summary>
/// Unpacks a single file from an archive or archive chain.
/// </summary>
private void UnpackOneFile(
IUnpackStreamContext streamContext,
ZipFileHeader header,
ref Stream archiveStream)
{
ZipFileInfo fileInfo = null;
Stream fileStream = null;
try
{
Func<Stream, Stream> compressionStreamCreator;
if (!ZipEngine.decompressionStreamCreators.TryGetValue(
header.compressionMethod, out compressionStreamCreator))
{
// Silently skip files of an unsupported compression method.
return;
}
long compressedSize;
long uncompressedSize;
long localHeaderOffset;
int archiveNumber;
uint crc;
header.GetZip64Fields(
out compressedSize,
out uncompressedSize,
out localHeaderOffset,
out archiveNumber,
out crc);
if (this.currentArchiveNumber != archiveNumber + 1)
{
if (archiveStream != null)
{
streamContext.CloseArchiveReadStream(
this.currentArchiveNumber,
String.Empty,
archiveStream);
archiveStream = null;
this.OnProgress(ArchiveProgressType.FinishArchive);
this.currentArchiveName = null;
}
this.currentArchiveNumber = (short)(archiveNumber + 1);
this.currentArchiveBytesProcessed = 0;
this.currentArchiveTotalBytes = 0;
archiveStream = this.OpenArchive(
streamContext, this.currentArchiveNumber);
FileStream archiveFileStream = archiveStream as FileStream;
this.currentArchiveName = (archiveFileStream != null ?
Path.GetFileName(archiveFileStream.Name) : null);
this.currentArchiveTotalBytes = archiveStream.Length;
this.currentArchiveNumber--;
this.OnProgress(ArchiveProgressType.StartArchive);
this.currentArchiveNumber++;
}
archiveStream.Seek(localHeaderOffset, SeekOrigin.Begin);
ZipFileHeader localHeader = new ZipFileHeader();
if (!localHeader.Read(archiveStream, false) ||
!ZipEngine.AreFilePathsEqual(localHeader.fileName, header.fileName))
{
string msg = "Could not read file: " + header.fileName;
throw new ZipException(msg);
}
fileInfo = header.ToZipFileInfo();
fileStream = streamContext.OpenFileWriteStream(
fileInfo.FullName,
fileInfo.Length,
fileInfo.LastWriteTime);
if (fileStream != null)
{
this.currentFileName = header.fileName;
this.currentFileBytesProcessed = 0;
this.currentFileTotalBytes = fileInfo.Length;
this.currentArchiveNumber--;
this.OnProgress(ArchiveProgressType.StartFile);
this.currentArchiveNumber++;
this.UnpackFileBytes(
streamContext,
fileInfo.FullName,
fileInfo.CompressedLength,
fileInfo.Length,
header.crc32,
fileStream,
compressionStreamCreator,
ref archiveStream);
}
}
finally
{
if (fileStream != null)
{
streamContext.CloseFileWriteStream(
fileInfo.FullName,
fileStream,
fileInfo.Attributes,
fileInfo.LastWriteTime);
this.currentArchiveNumber--;
this.OnProgress(ArchiveProgressType.FinishFile);
this.currentArchiveNumber++;
}
}
}
/// <summary>
/// Adds one file to a zip archive in the process of being created.
/// </summary>
private ZipFileHeader PackOneFile(
IPackStreamContext streamContext,
string file,
long maxArchiveSize,
bool forceZip64,
ref Stream archiveStream)
{
Stream fileStream = null;
int headerArchiveNumber = 0;
try
{
// TODO: call GetOption to get compression method for the specific file
ZipCompressionMethod compressionMethod = ZipCompressionMethod.Deflate;
if (this.CompressionLevel == CompressionLevel.None)
{
compressionMethod = ZipCompressionMethod.Store;
}
Func<Stream, Stream> compressionStreamCreator;
if (!ZipEngine.compressionStreamCreators.TryGetValue(
compressionMethod, out compressionStreamCreator))
{
return null;
}
FileAttributes attributes;
DateTime lastWriteTime;
fileStream = streamContext.OpenFileReadStream(
file, out attributes, out lastWriteTime);
if (fileStream == null)
{
return null;
}
this.currentFileName = file;
this.currentFileNumber++;
this.currentFileTotalBytes = fileStream.Length;
this.currentFileBytesProcessed = 0;
this.OnProgress(ArchiveProgressType.StartFile);
ZipFileInfo fileInfo = new ZipFileInfo(
file,
this.currentArchiveNumber,
attributes,
lastWriteTime,
fileStream.Length,
0,
compressionMethod);
bool zip64 = forceZip64 || fileStream.Length >= (long)UInt32.MaxValue;
ZipFileHeader fileHeader = new ZipFileHeader(fileInfo, zip64);
this.CheckArchiveWriteStream(
streamContext,
maxArchiveSize,
fileHeader.GetSize(false),
ref archiveStream);
long headerPosition = archiveStream.Position;
fileHeader.Write(archiveStream, false);
headerArchiveNumber = this.currentArchiveNumber;
uint crc;
long bytesWritten = this.PackFileBytes(
streamContext,
fileStream,
maxArchiveSize,
compressionStreamCreator,
ref archiveStream,
out crc);
fileHeader.Update(
bytesWritten,
fileStream.Length,
crc,
headerPosition,
headerArchiveNumber);
streamContext.CloseFileReadStream(file, fileStream);
fileStream = null;
// Go back and rewrite the updated file header.
if (this.currentArchiveNumber == headerArchiveNumber)
{
long fileEndPosition = archiveStream.Position;
archiveStream.Seek(headerPosition, SeekOrigin.Begin);
fileHeader.Write(archiveStream, false);
archiveStream.Seek(fileEndPosition, SeekOrigin.Begin);
}
else
{
// The file spanned archives, so temporarily reopen
// the archive where it started.
string headerArchiveName = streamContext.GetArchiveName(
headerArchiveNumber + 1);
Stream headerStream = null;
try
{
headerStream = streamContext.OpenArchiveWriteStream(
headerArchiveNumber, headerArchiveName, false, this);
headerStream.Seek(headerPosition, SeekOrigin.Begin);
fileHeader.Write(headerStream, false);
}
finally
{
if (headerStream != null)
{
streamContext.CloseArchiveWriteStream(
headerArchiveNumber, headerArchiveName, headerStream);
}
}
}
this.OnProgress(ArchiveProgressType.FinishFile);
return fileHeader;
}
finally
{
if (fileStream != null)
{
streamContext.CloseFileReadStream(
this.currentFileName, fileStream);
}
}
}
/// <summary>
/// Reads all the file headers from the central directory in the main archive.
/// </summary>
private IList<ZipFileHeader> GetCentralDirectory(IUnpackStreamContext streamContext)
{
Stream archiveStream = null;
this.currentArchiveNumber = 0;
try
{
List<ZipFileHeader> headers = new List<ZipFileHeader>();
archiveStream = this.OpenArchive(streamContext, 0);
ZipEndOfCentralDirectory eocd = this.GetEOCD(streamContext, archiveStream);
if (eocd == null)
{
return null;
}
else if (eocd.totalEntries == 0)
{
return headers;
}
headers.Capacity = (int)eocd.totalEntries;
if (eocd.dirOffset > archiveStream.Length - ZipFileHeader.CFH_FIXEDSIZE)
{
streamContext.CloseArchiveReadStream(
this.currentArchiveNumber, String.Empty, archiveStream);
archiveStream = null;
}
else
{
archiveStream.Seek(eocd.dirOffset, SeekOrigin.Begin);
uint sig = new BinaryReader(archiveStream).ReadUInt32();
if (sig != ZipFileHeader.CFHSIG)
{
streamContext.CloseArchiveReadStream(
this.currentArchiveNumber, String.Empty, archiveStream);
archiveStream = null;
}
}
if (archiveStream == null)
{
this.currentArchiveNumber = (short)(eocd.dirStartDiskNumber + 1);
archiveStream = streamContext.OpenArchiveReadStream(
this.currentArchiveNumber, String.Empty, this);
if (archiveStream == null)
{
return null;
}
}
archiveStream.Seek(eocd.dirOffset, SeekOrigin.Begin);
while (headers.Count < eocd.totalEntries)
{
ZipFileHeader header = new ZipFileHeader();
if (!header.Read(archiveStream, true))
{
throw new ZipException(
"Missing or invalid central directory file header");
}
headers.Add(header);
if (headers.Count < eocd.totalEntries &&
archiveStream.Position == archiveStream.Length)
{
streamContext.CloseArchiveReadStream(
this.currentArchiveNumber, String.Empty, archiveStream);
this.currentArchiveNumber++;
archiveStream = streamContext.OpenArchiveReadStream(
this.currentArchiveNumber, String.Empty, this);
if (archiveStream == null)
{
this.currentArchiveNumber = 0;
archiveStream = streamContext.OpenArchiveReadStream(
this.currentArchiveNumber, String.Empty, this);
}
}
}
return headers;
}
finally
{
if (archiveStream != null)
{
streamContext.CloseArchiveReadStream(
this.currentArchiveNumber, String.Empty, archiveStream);
}
}
}
/// <summary>
/// Gets the offset of an archive that is positioned 0 or more bytes
/// from the start of the Stream.
/// </summary>
/// <param name="stream">A stream for reading the archive.</param>
/// <returns>The offset in bytes of the archive,
/// or -1 if no archive is found in the Stream.</returns>
/// <remarks>The archive must begin on a 4-byte boundary.</remarks>
public override long FindArchiveOffset(Stream stream)
{
if (stream == null)
{
throw new ArgumentNullException("stream");
}
long offset = base.FindArchiveOffset(stream);
if (offset > 0)
{
// Some self-extract packages include the exe stub in file offset calculations.
// Check the first header directory offset to decide whether the entire
// archive needs to be offset or not.
ZipEndOfCentralDirectory eocd = this.GetEOCD(null, stream);
if (eocd != null && eocd.totalEntries > 0)
{
stream.Seek(eocd.dirOffset, SeekOrigin.Begin);
ZipFileHeader header = new ZipFileHeader();
if (header.Read(stream, true) && header.localHeaderOffset < stream.Length)
{
stream.Seek(header.localHeaderOffset, SeekOrigin.Begin);
if (header.Read(stream, false))
{
return 0;
}
}
}
}
return offset;
}