//writes eocd, and if needed, zip 64 eocd, zip64 eocd locator
//should only throw an exception in extremely exceptional cases because it is called from dispose
private void WriteArchiveEpilogue(Int64 startOfCentralDirectory, Int64 sizeOfCentralDirectory)
{
//determine if we need Zip 64
Boolean needZip64 = false;
if (startOfCentralDirectory >= UInt32.MaxValue ||
sizeOfCentralDirectory >= UInt32.MaxValue ||
_entries.Count >= ZipHelper.Mask16Bit
#if DEBUG_FORCE_ZIP64
|| _forceZip64
#endif
)
{
needZip64 = true;
}
//if we need zip 64, write zip 64 eocd and locator
if (needZip64)
{
Int64 zip64EOCDRecordStart = _archiveStream.Position;
Zip64EndOfCentralDirectoryRecord.WriteBlock(_archiveStream, _entries.Count, startOfCentralDirectory, sizeOfCentralDirectory);
Zip64EndOfCentralDirectoryLocator.WriteBlock(_archiveStream, zip64EOCDRecordStart);
}
//write normal eocd
ZipEndOfCentralDirectoryBlock.WriteBlock(_archiveStream, _entries.Count, startOfCentralDirectory, sizeOfCentralDirectory, _archiveComment);
}
public static Boolean TryReadBlock(BinaryReader reader, out ZipEndOfCentralDirectoryBlock eocdBlock)
{
eocdBlock = new ZipEndOfCentralDirectoryBlock();
if (reader.ReadUInt32() != SignatureConstant)
{
return(false);
}
eocdBlock.Signature = SignatureConstant;
eocdBlock.NumberOfThisDisk = reader.ReadUInt16();
eocdBlock.NumberOfTheDiskWithTheStartOfTheCentralDirectory = reader.ReadUInt16();
eocdBlock.NumberOfEntriesInTheCentralDirectoryOnThisDisk = reader.ReadUInt16();
eocdBlock.NumberOfEntriesInTheCentralDirectory = reader.ReadUInt16();
eocdBlock.SizeOfCentralDirectory = reader.ReadUInt32();
eocdBlock.OffsetOfStartOfCentralDirectoryWithRespectToTheStartingDiskNumber = reader.ReadUInt32();
UInt16 commentLength = reader.ReadUInt16();
eocdBlock.ArchiveComment = reader.ReadBytes(commentLength);
return(true);
}
//This function reads all the EOCD stuff it needs to find the offset to the start of the central directory
//This offset gets put in _centralDirectoryStart and the number of this disk gets put in _numberOfThisDisk
//Also does some verification that this isn't a split/spanned archive
//Also checks that offset to CD isn't out of bounds
private void ReadEndOfCentralDirectory()
{
try
{
//this seeks to the start of the end of central directory record
_archiveStream.Seek(-ZipEndOfCentralDirectoryBlock.SizeOfBlockWithoutSignature, SeekOrigin.End);
if (!ZipHelper.SeekBackwardsToSignature(_archiveStream, ZipEndOfCentralDirectoryBlock.SignatureConstant))
{
throw new InvalidDataException(SR.EOCDNotFound);
}
Int64 eocdStart = _archiveStream.Position;
//read the EOCD
ZipEndOfCentralDirectoryBlock eocd;
Boolean eocdProper = ZipEndOfCentralDirectoryBlock.TryReadBlock(_archiveReader, out eocd);
Debug.Assert(eocdProper); //we just found this using the signature finder, so it should be okay
if (eocd.NumberOfThisDisk != eocd.NumberOfTheDiskWithTheStartOfTheCentralDirectory)
{
throw new InvalidDataException(SR.SplitSpanned);
}
_numberOfThisDisk = eocd.NumberOfThisDisk;
_centralDirectoryStart = eocd.OffsetOfStartOfCentralDirectoryWithRespectToTheStartingDiskNumber;
if (eocd.NumberOfEntriesInTheCentralDirectory != eocd.NumberOfEntriesInTheCentralDirectoryOnThisDisk)
{
throw new InvalidDataException(SR.SplitSpanned);
}
_expectedNumberOfEntries = eocd.NumberOfEntriesInTheCentralDirectory;
//only bother saving the comment if we are in update mode
if (_mode == ZipArchiveMode.Update)
{
_archiveComment = eocd.ArchiveComment;
}
//only bother looking for zip64 EOCD stuff if we suspect it is needed because some value is FFFFFFFFF
//because these are the only two values we need, we only worry about these
//if we don't find the zip64 EOCD, we just give up and try to use the original values
if (eocd.NumberOfThisDisk == ZipHelper.Mask16Bit ||
eocd.OffsetOfStartOfCentralDirectoryWithRespectToTheStartingDiskNumber == ZipHelper.Mask32Bit ||
eocd.NumberOfEntriesInTheCentralDirectory == ZipHelper.Mask16Bit)
{
//we need to look for zip 64 EOCD stuff
//seek to the zip 64 EOCD locator
_archiveStream.Seek(eocdStart - Zip64EndOfCentralDirectoryLocator.SizeOfBlockWithoutSignature, SeekOrigin.Begin);
//if we don't find it, assume it doesn't exist and use data from normal eocd
if (ZipHelper.SeekBackwardsToSignature(_archiveStream, Zip64EndOfCentralDirectoryLocator.SignatureConstant))
{
//use locator to get to Zip64EOCD
Zip64EndOfCentralDirectoryLocator locator;
Boolean zip64eocdLocatorProper = Zip64EndOfCentralDirectoryLocator.TryReadBlock(_archiveReader, out locator);
Debug.Assert(zip64eocdLocatorProper); //we just found this using the signature finder, so it should be okay
if (locator.OffsetOfZip64EOCD > (UInt64)Int64.MaxValue)
{
throw new InvalidDataException(SR.FieldTooBigOffsetToZip64EOCD);
}
Int64 zip64EOCDOffset = (Int64)locator.OffsetOfZip64EOCD;
_archiveStream.Seek(zip64EOCDOffset, SeekOrigin.Begin);
//read Zip64EOCD
Zip64EndOfCentralDirectoryRecord record;
if (!Zip64EndOfCentralDirectoryRecord.TryReadBlock(_archiveReader, out record))
{
throw new InvalidDataException(SR.Zip64EOCDNotWhereExpected);
}
_numberOfThisDisk = record.NumberOfThisDisk;
if (record.NumberOfEntriesTotal > (UInt64)Int64.MaxValue)
{
throw new InvalidDataException(SR.FieldTooBigNumEntries);
}
if (record.OffsetOfCentralDirectory > (UInt64)Int64.MaxValue)
{
throw new InvalidDataException(SR.FieldTooBigOffsetToCD);
}
if (record.NumberOfEntriesTotal != record.NumberOfEntriesOnThisDisk)
{
throw new InvalidDataException(SR.SplitSpanned);
}
_expectedNumberOfEntries = (Int64)record.NumberOfEntriesTotal;
_centralDirectoryStart = (Int64)record.OffsetOfCentralDirectory;
}
}
if (_centralDirectoryStart > _archiveStream.Length)
{
throw new InvalidDataException(SR.FieldTooBigOffsetToCD);
}
}
catch (EndOfStreamException ex)
{
throw new InvalidDataException(SR.CDCorrupt, ex);
}
catch (IOException ex)
{
throw new InvalidDataException(SR.CDCorrupt, ex);
}
}