/// <summary>
/// Reads one entry from the zip directory structure in the zip file.
/// </summary>
/// <param name="s">the stream from which to read.</param>
/// <param name="expectedEncoding">
/// The text encoding to use if the entry is not marked UTF-8.
/// </param>
/// <returns>the entry read from the archive.</returns>
public static ZipEntry ReadDirEntry(System.IO.Stream s, System.Text.Encoding expectedEncoding)
{
long cdrPosition = s.Position;
int signature = ESRI.ArcGIS.Client.Toolkit.DataSources.Kml.Zip.SharedUtilities.ReadSignature(s);
// return null if this is not a local file header signature
if (IsNotValidZipDirEntrySig(signature))
{
s.Seek(-4, System.IO.SeekOrigin.Current);
// Getting "not a ZipDirEntry signature" here is not always wrong or an error.
// This can happen when walking through a zipfile. After the last ZipDirEntry,
// we expect to read an EndOfCentralDirectorySignature. When we get this is how we
// know we've reached the end of the central directory.
if (signature != ZipConstants.EndOfCentralDirectorySignature &&
signature != ZipConstants.Zip64EndOfCentralDirectoryRecordSignature)
{
throw new BadReadException(String.Format(" ZipEntry::ReadDirEntry(): Bad signature (0x{0:X8}) at position 0x{1:X8}", signature, s.Position));
}
return null;
}
int bytesRead = 42 + 4;
byte[] block = new byte[42];
int n = s.Read(block, 0, block.Length);
if (n != block.Length) return null;
int i = 0;
ZipEntry zde = new ZipEntry();
zde._archiveStream = s;
zde._cdrPosition = cdrPosition;
zde._VersionMadeBy = (short)(block[i++] + block[i++] * 256);
zde._VersionNeeded = (short)(block[i++] + block[i++] * 256);
zde._BitField = (short)(block[i++] + block[i++] * 256);
zde._CompressionMethod = (short)(block[i++] + block[i++] * 256);
zde._TimeBlob = block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256;
zde._LastModified = ESRI.ArcGIS.Client.Toolkit.DataSources.Kml.Zip.SharedUtilities.PackedToDateTime(zde._TimeBlob);
zde._Crc32 = block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256;
zde._CompressedSize = (uint)(block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256);
zde._UncompressedSize = (uint)(block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256);
//DateTime lastModified = Ionic.Utils.Zip.SharedUtilities.PackedToDateTime(lastModDateTime);
//i += 24;
zde._filenameLength = (short)(block[i++] + block[i++] * 256);
zde._extraFieldLength = (short)(block[i++] + block[i++] * 256);
zde._commentLength = (short)(block[i++] + block[i++] * 256);
//Int16 diskNumber = (short)(block[i++] + block[i++] * 256);
i += 2;
zde._InternalFileAttrs = (short)(block[i++] + block[i++] * 256);
zde._ExternalFileAttrs = block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256;
zde._RelativeOffsetOfLocalHeader = (uint)(block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256);
block = new byte[zde._filenameLength];
n = s.Read(block, 0, block.Length);
bytesRead += n;
if ((zde._BitField & 0x0800) == 0x0800)
{
// UTF-8 is in use
zde._LocalFileName = ESRI.ArcGIS.Client.Toolkit.DataSources.Kml.Zip.SharedUtilities.Utf8StringFromBuffer(block, block.Length);
}
else
{
zde._LocalFileName = ESRI.ArcGIS.Client.Toolkit.DataSources.Kml.Zip.SharedUtilities.StringFromBuffer(block, block.Length, expectedEncoding);
}
// Console.WriteLine("\nEntry : {0}", zde._LocalFileName);
// Console.WriteLine(" V Madeby: 0x{0:X4}", zde._VersionMadeBy);
// Console.WriteLine(" V Needed: 0x{0:X4}", zde._VersionNeeded);
// Console.WriteLine(" BitField: 0x{0:X4}", zde._BitField);
// Console.WriteLine(" Compression: 0x{0:X4}", zde._CompressionMethod);
// Console.WriteLine(" Lastmod: {0}", zde._LastModified.ToString("u"));
// Console.WriteLine(" CRC: 0x{0:X8}", zde._Crc32);
// Console.WriteLine(" Comp: 0x{0:X8} ({0})", zde._CompressedSize);
// Console.WriteLine(" Uncomp: 0x{0:X8} ({0})", zde._UncompressedSize);
zde._FileNameInArchive = zde._LocalFileName;
if (zde.AttributesIndicateDirectory) zde.MarkAsDirectory(); // may append a slash to filename if nec.
// workitem 6898
if (zde._LocalFileName.EndsWith("/")) zde.MarkAsDirectory();
zde._CompressedFileDataSize = zde._CompressedSize;
if ((zde._BitField & 0x01) == 0x01)
{
zde._Encryption = EncryptionAlgorithm.PkzipWeak; // this may change after processing the Extra field
}
if (zde._extraFieldLength > 0)
{
//Console.WriteLine("ZDE Extra Field length: {0}", zde._extraFieldLength);
zde._InputUsesZip64 = ((uint)zde._CompressedSize == 0xFFFFFFFF ||
(uint)zde._UncompressedSize == 0xFFFFFFFF ||
(uint)zde._RelativeOffsetOfLocalHeader == 0xFFFFFFFF);
bytesRead += zde.ProcessExtraField(zde._extraFieldLength);
zde._CompressedFileDataSize = zde._CompressedSize;
//Console.WriteLine(" Compressed: 0x{0:X8} ({0})", zde._CompressedSize);
}
// we've processed the extra field, so we know the encryption method is set now.
if (zde._Encryption == EncryptionAlgorithm.PkzipWeak)
{
// the "encryption header" of 12 bytes precedes the file data
zde._CompressedFileDataSize -= 12;
}
if (zde._commentLength > 0)
{
block = new byte[zde._commentLength];
n = s.Read(block, 0, block.Length);
bytesRead += n;
if ((zde._BitField & 0x0800) == 0x0800)
{
// UTF-8 is in use
zde._Comment = ESRI.ArcGIS.Client.Toolkit.DataSources.Kml.Zip.SharedUtilities.Utf8StringFromBuffer(block, block.Length);
}
else
{
zde._Comment = ESRI.ArcGIS.Client.Toolkit.DataSources.Kml.Zip.SharedUtilities.StringFromBuffer(block, block.Length, expectedEncoding);
}
}
zde._LengthOfDirEntry = bytesRead;
return zde;
}
/// <summary>
/// Reads one ZipEntry from the given stream. If the entry is encrypted, we don't
/// decrypt at this point. We also do not decompress. Mostly we read metadata.
/// </summary>
/// <param name="zf">the zipfile this entry belongs to.</param>
/// <param name="first">true of this is the first entry being read from the stream.</param>
/// <returns>the ZipEntry read from the stream.</returns>
internal static ZipEntry Read(ZipFile zf, bool first)
{
System.IO.Stream s = zf.ReadStream;
System.Text.Encoding defaultEncoding = zf.ProvisionalAlternateEncoding;
ZipEntry entry = new ZipEntry();
entry._Source = EntrySource.Zipfile;
entry._zipfile = zf;
entry._archiveStream = s;
if (first) HandlePK00Prefix(s);
if (!ReadHeader(entry, defaultEncoding)) return null;
// store the position in the stream for this entry
entry.__FileDataPosition = entry.ArchiveStream.Position;
// seek past the data without reading it. We will read on Extract()
s.Seek(entry._CompressedFileDataSize, System.IO.SeekOrigin.Current);
// workitem 6607 - don't seek for directories
// finally, seek past the (already read) Data descriptor if necessary
if (((entry._BitField & 0x0008) == 0x0008) && !entry.FileName.EndsWith("/"))
{
// _InputUsesZip64 is set in ReadHeader()
int DescriptorSize = (entry._InputUsesZip64) ? 24 : 16;
s.Seek(DescriptorSize, System.IO.SeekOrigin.Current);
}
// workitem 5306
// http://www.codeplex.com/DotNetZip/WorkItem/View.aspx?WorkItemId=5306
HandleUnexpectedDataDescriptor(entry);
return entry;
}
private static void HandleUnexpectedDataDescriptor(ZipEntry entry)
{
System.IO.Stream s = entry.ArchiveStream;
// In some cases, the "data descriptor" is present, without a signature, even when bit 3 of the BitField is NOT SET.
// This is the CRC, followed
// by the compressed length and the uncompressed length (4 bytes for each
// of those three elements). Need to check that here.
//
uint datum = (uint)ESRI.ArcGIS.Client.Toolkit.DataSources.Kml.Zip.SharedUtilities.ReadInt(s);
if (datum == entry._Crc32)
{
int sz = ESRI.ArcGIS.Client.Toolkit.DataSources.Kml.Zip.SharedUtilities.ReadInt(s);
if (sz == entry._CompressedSize)
{
sz = ESRI.ArcGIS.Client.Toolkit.DataSources.Kml.Zip.SharedUtilities.ReadInt(s);
if (sz == entry._UncompressedSize)
{
// ignore everything and discard it.
}
else
s.Seek(-12, System.IO.SeekOrigin.Current); // unread the three blocks
}
else
s.Seek(-8, System.IO.SeekOrigin.Current); // unread the two blocks
}
else
s.Seek(-4, System.IO.SeekOrigin.Current); // unread the block
}
private static bool ReadHeader(ZipEntry ze, System.Text.Encoding defaultEncoding)
{
int bytesRead = 0;
ze._RelativeOffsetOfLocalHeader = (int)ze.ArchiveStream.Position;
int signature = ESRI.ArcGIS.Client.Toolkit.DataSources.Kml.Zip.SharedUtilities.ReadSignature(ze.ArchiveStream);
bytesRead += 4;
// Return false if this is not a local file header signature.
if (ZipEntry.IsNotValidSig(signature))
{
// Getting "not a ZipEntry signature" is not always wrong or an error.
// This will happen after the last entry in a zipfile. In that case, we
// expect to read :
// a ZipDirEntry signature (if a non-empty zip file) or
// a ZipConstants.EndOfCentralDirectorySignature.
//
// Anything else is a surprise.
ze.ArchiveStream.Seek(-4, System.IO.SeekOrigin.Current); // unread the signature
if (ZipEntry.IsNotValidZipDirEntrySig(signature) && (signature != ZipConstants.EndOfCentralDirectorySignature))
{
throw new BadReadException(String.Format(" ZipEntry::ReadHeader(): Bad signature (0x{0:X8}) at position 0x{1:X8}", signature, ze.ArchiveStream.Position));
}
return false;
}
byte[] block = new byte[26];
int n = ze.ArchiveStream.Read(block, 0, block.Length);
if (n != block.Length) return false;
bytesRead += n;
int i = 0;
ze._VersionNeeded = (short)(block[i++] + block[i++] * 256);
ze._BitField = (short)(block[i++] + block[i++] * 256);
ze._CompressionMethod = (short)(block[i++] + block[i++] * 256);
ze._TimeBlob = block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256;
// transform the time data into something usable (a DateTime)
ze._LastModified = ESRI.ArcGIS.Client.Toolkit.DataSources.Kml.Zip.SharedUtilities.PackedToDateTime(ze._TimeBlob);
// NB: if ((ze._BitField & 0x0008) != 0x0008), then the Compressed, uncompressed and
// CRC values are not true values; the true values will follow the entry data.
// Nevertheless, regardless of the statis of bit 3 in the bitfield, the slots for
// the three amigos may contain marker values for ZIP64. So we must read them.
{
ze._Crc32 = (Int32)(block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256);
ze._CompressedSize = (uint)(block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256);
ze._UncompressedSize = (uint)(block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256);
// validate ZIP64? No. We don't need to be pedantic about it.
//if (((uint)ze._CompressedSize == 0xFFFFFFFF &&
// (uint)ze._UncompressedSize != 0xFFFFFFFF) ||
// ((uint)ze._CompressedSize != 0xFFFFFFFF &&
// (uint)ze._UncompressedSize == 0xFFFFFFFF))
// throw new BadReadException(String.Format(" ZipEntry::Read(): Inconsistent uncompressed size (0x{0:X8}) for zip64, at position 0x{1:X16}", ze._UncompressedSize, ze.ArchiveStream.Position));
if ((uint)ze._CompressedSize == 0xFFFFFFFF ||
(uint)ze._UncompressedSize == 0xFFFFFFFF)
ze._InputUsesZip64 = true;
//throw new BadReadException(" DotNetZip does not currently support reading the ZIP64 format.");
}
// else
// {
// // The CRC, compressed size, and uncompressed size stored here are not valid.
// // The actual values are stored later in the stream.
// // Here, we advance the pointer to skip the dummy data.
// i += 12;
// }
Int16 filenameLength = (short)(block[i++] + block[i++] * 256);
Int16 extraFieldLength = (short)(block[i++] + block[i++] * 256);
block = new byte[filenameLength];
n = ze.ArchiveStream.Read(block, 0, block.Length);
bytesRead += n;
// if the UTF8 bit is set for this entry, we override the encoding the application requested.
ze._actualEncoding = ((ze._BitField & 0x0800) == 0x0800)
? System.Text.Encoding.UTF8
: defaultEncoding;
// need to use this form of GetString() for .NET CF
ze._FileNameInArchive = ze._actualEncoding.GetString(block, 0, block.Length);
// when creating an entry by reading, the LocalFileName is the same as the FileNameInArchive
ze._LocalFileName = ze._FileNameInArchive;
// workitem 6898
if (ze._LocalFileName.EndsWith("/")) ze.MarkAsDirectory();
bytesRead += ze.ProcessExtraField(extraFieldLength);
ze._LengthOfTrailer = 0;
// workitem 6607 - don't read for directories
// actually get the compressed size and CRC if necessary
if (!ze._LocalFileName.EndsWith("/") && (ze._BitField & 0x0008) == 0x0008)
{
// This descriptor exists only if bit 3 of the general
// purpose bit flag is set (see below). It is byte aligned
// and immediately follows the last byte of compressed data.
// This descriptor is used only when it was not possible to
// seek in the output .ZIP file, e.g., when the output .ZIP file
// was standard output or a non-seekable device. For ZIP64(tm) format
// archives, the compressed and uncompressed sizes are 8 bytes each.
long posn = ze.ArchiveStream.Position;
// Here, we're going to loop until we find a ZipEntryDataDescriptorSignature and
// a consistent data record after that. To be consistent, the data record must
// indicate the length of the entry data.
bool wantMore = true;
long SizeOfDataRead = 0;
int tries = 0;
while (wantMore)
{
tries++;
// We call the FindSignature shared routine to find the specified signature
// in the already-opened zip archive, starting from the current cursor
// position in that filestream. There are two possibilities: either we
// find the signature or we don't. If we cannot find it, then the routine
// returns -1, and the ReadHeader() method returns false, indicating we
// cannot read a legal entry header. If we have found it, then the
// FindSignature() method returns the number of bytes in the stream we had
// to seek forward, to find the sig. We need this to determine if the zip
// entry is valid, later.
long d = ESRI.ArcGIS.Client.Toolkit.DataSources.Kml.Zip.SharedUtilities.FindSignature(ze.ArchiveStream, ZipConstants.ZipEntryDataDescriptorSignature);
if (d == -1) return false;
// total size of data read (through all loops of this).
SizeOfDataRead += d;
if (ze._InputUsesZip64 == true)
{
// read 1x 4-byte (CRC) and 2x 8-bytes (Compressed Size, Uncompressed Size)
block = new byte[20];
n = ze.ArchiveStream.Read(block, 0, block.Length);
if (n != 20) return false;
// do not increment bytesRead - it is for entry header only.
// the data we have just read is a footer (falls after the file data)
//bytesRead += n;
i = 0;
ze._Crc32 = (Int32)(block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256);
ze._CompressedSize = BitConverter.ToInt64(block, i);
i += 8;
ze._UncompressedSize = BitConverter.ToInt64(block, i);
i += 8;
ze._LengthOfTrailer += 24; // bytes including sig, CRC, Comp and Uncomp sizes
}
else
{
// read 3x 4-byte fields (CRC, Compressed Size, Uncompressed Size)
block = new byte[12];
n = ze.ArchiveStream.Read(block, 0, block.Length);
if (n != 12) return false;
// do not increment bytesRead - it is for entry header only.
// the data we have just read is a footer (falls after the file data)
//bytesRead += n;
i = 0;
ze._Crc32 = (Int32)(block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256);
ze._CompressedSize = (uint)(block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256);
ze._UncompressedSize = (uint)(block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256);
ze._LengthOfTrailer += 16; // bytes including sig, CRC, Comp and Uncomp sizes
}
wantMore = (SizeOfDataRead != ze._CompressedSize);
if (wantMore)
{
// Seek back to un-read the last 12 bytes - maybe THEY contain
// the ZipEntryDataDescriptorSignature.
// (12 bytes for the CRC, Comp and Uncomp size.)
ze.ArchiveStream.Seek(-12, System.IO.SeekOrigin.Current);
// Adjust the size to account for the false signature read in
// FindSignature().
SizeOfDataRead += 4;
}
}
//if (SizeOfDataRead != ze._CompressedSize)
// throw new BadReadException("Data format error (bit 3 is set)");
// seek back to previous position, to prepare to read file data
ze.ArchiveStream.Seek(posn, System.IO.SeekOrigin.Begin);
}
ze._CompressedFileDataSize = ze._CompressedSize;
// bit 0 set indicates that some kind of encryption is in use
if ((ze._BitField & 0x01) == 0x01)
{
#if AESCRYPTO
if (ze.Encryption == EncryptionAlgorithm.WinZipAes128 ||
ze.Encryption == EncryptionAlgorithm.WinZipAes256)
{
// read in the WinZip AES metadata
ze._aesCrypto = WinZipAesCrypto.ReadFromStream(null, ze._KeyStrengthInBits, ze.ArchiveStream);
bytesRead += ze._aesCrypto.SizeOfEncryptionMetadata - 10;
ze._CompressedFileDataSize = ze.CompressedSize - ze._aesCrypto.SizeOfEncryptionMetadata;
ze._LengthOfTrailer += 10;
}
else
#endif
{
// read in the header data for "weak" encryption
ze._WeakEncryptionHeader = new byte[12];
bytesRead += ZipEntry.ReadWeakEncryptionHeader(ze._archiveStream, ze._WeakEncryptionHeader);
// decrease the filedata size by 12 bytes
ze._CompressedFileDataSize -= 12;
}
}
// Remember the size of the blob for this entry.
// We also have the starting position in the stream for this entry.
ze._LengthOfHeader = bytesRead;
ze._TotalEntrySize = ze._LengthOfHeader + ze._CompressedSize + ze._LengthOfTrailer;
// We've read in the regular entry header, the extra field, and any encryption
// header. The pointer in the file is now at the start of the filedata, which is
// potentially compressed and encrypted. Just ahead in the file, there are
// _CompressedFileDataSize bytes of data, followed by potentially a non-zero
// length trailer, consisting of optionally, some encryption stuff (10 byte MAC for AES), and
// the bit-3 trailer (16 or 24 bytes).
return true;
}
