public static void ReadEndOfCentralDirectory(Stream stream, BinaryReader reader, out long expectedNumberOfEntries, out long centralDirectoryStart)
{
try
{
// this seeks to the start of the end of central directory record
stream.Seek(-ZipEndOfCentralDirectoryBlock.SizeOfBlockWithoutSignature, SeekOrigin.End);
if (!ZipHelper.SeekBackwardsToSignature(stream, ZipEndOfCentralDirectoryBlock.SignatureConstant))
{
throw new ZipArchiveException("SignatureConstant");
}
long eocdStart = stream.Position;
// read the EOCD
ZipEndOfCentralDirectoryBlock eocd;
bool eocdProper = ZipEndOfCentralDirectoryBlock.TryReadBlock(reader, 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 ZipArchiveException("SplitSpanned");
}
centralDirectoryStart = eocd.OffsetOfStartOfCentralDirectoryWithRespectToTheStartingDiskNumber;
if (eocd.NumberOfEntriesInTheCentralDirectory != eocd.NumberOfEntriesInTheCentralDirectoryOnThisDisk)
{
throw new ZipArchiveException("SplitSpanned");
}
expectedNumberOfEntries = eocd.NumberOfEntriesInTheCentralDirectory;
// 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
stream.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(stream, Zip64EndOfCentralDirectoryLocator.SignatureConstant))
{
// use locator to get to Zip64EOCD
Zip64EndOfCentralDirectoryLocator locator;
bool zip64eocdLocatorProper = Zip64EndOfCentralDirectoryLocator.TryReadBlock(reader, out locator);
Debug.Assert(zip64eocdLocatorProper); // we just found this using the signature finder, so it should be okay
if (locator.OffsetOfZip64EOCD > long.MaxValue)
{
throw new ZipArchiveException("FieldTooBigOffsetToZip64EOCD");
}
long zip64EOCDOffset = (long)locator.OffsetOfZip64EOCD;
stream.Seek(zip64EOCDOffset, SeekOrigin.Begin);
// read Zip64EOCD
Zip64EndOfCentralDirectoryRecord record;
if (!Zip64EndOfCentralDirectoryRecord.TryReadBlock(reader, out record))
{
throw new ZipArchiveException("Zip64EOCDNotWhereExpected");
}
if (record.NumberOfEntriesTotal > long.MaxValue)
{
throw new ZipArchiveException("FieldTooBigNumEntries");
}
if (record.OffsetOfCentralDirectory > long.MaxValue)
{
throw new ZipArchiveException("FieldTooBigOffsetToCD");
}
if (record.NumberOfEntriesTotal != record.NumberOfEntriesOnThisDisk)
{
throw new ZipArchiveException("SplitSpanned");
}
expectedNumberOfEntries = (long)record.NumberOfEntriesTotal;
centralDirectoryStart = (long)record.OffsetOfCentralDirectory;
}
}
if (centralDirectoryStart > stream.Length)
{
throw new ZipArchiveException("FieldTooBigOffsetToCD");
}
}
catch (EndOfStreamException ex)
{
throw new ZipArchiveException("CDCorrupt", ex);
}
catch (IOException ex)
{
throw new ZipArchiveException("CDCorrupt", ex);
}
}
public static void ReadEndOfCentralDirectory(Stream stream, BinaryReader reader, out long expectedNumberOfEntries, out long centralDirectoryStart)
{
try
{
stream.Seek(-ZipEndOfCentralDirectoryBlock.SizeOfBlockWithoutSignature, SeekOrigin.End);
if (!ZipHelper.SeekBackwardsToSignature(stream, ZipEndOfCentralDirectoryBlock.SignatureConstant))
{
throw new ZipArchiveException("SignatureConstant");
}
long eocdStart = stream.Position;
ZipEndOfCentralDirectoryBlock eocd;
bool eocdProper = ZipEndOfCentralDirectoryBlock.TryReadBlock(reader, out eocd);
Debug.Assert(eocdProper);
if (eocd.NumberOfThisDisk != eocd.NumberOfTheDiskWithTheStartOfTheCentralDirectory)
{
throw new ZipArchiveException("SplitSpanned");
}
centralDirectoryStart = eocd.OffsetOfStartOfCentralDirectoryWithRespectToTheStartingDiskNumber;
if (eocd.NumberOfEntriesInTheCentralDirectory != eocd.NumberOfEntriesInTheCentralDirectoryOnThisDisk)
{
throw new ZipArchiveException("SplitSpanned");
}
expectedNumberOfEntries = eocd.NumberOfEntriesInTheCentralDirectory;
if (eocd.NumberOfThisDisk == ZipHelper.Mask16Bit ||
eocd.OffsetOfStartOfCentralDirectoryWithRespectToTheStartingDiskNumber == ZipHelper.Mask32Bit ||
eocd.NumberOfEntriesInTheCentralDirectory == ZipHelper.Mask16Bit)
{
stream.Seek(eocdStart - Zip64EndOfCentralDirectoryLocator.SizeOfBlockWithoutSignature, SeekOrigin.Begin);
if (ZipHelper.SeekBackwardsToSignature(stream, Zip64EndOfCentralDirectoryLocator.SignatureConstant))
{
Zip64EndOfCentralDirectoryLocator locator;
bool zip64eocdLocatorProper = Zip64EndOfCentralDirectoryLocator.TryReadBlock(reader, out locator);
Debug.Assert(zip64eocdLocatorProper);
if (locator.OffsetOfZip64EOCD > long.MaxValue)
{
throw new ZipArchiveException("FieldTooBigOffsetToZip64EOCD");
}
long zip64EOCDOffset = (long)locator.OffsetOfZip64EOCD;
stream.Seek(zip64EOCDOffset, SeekOrigin.Begin);
Zip64EndOfCentralDirectoryRecord record;
if (!Zip64EndOfCentralDirectoryRecord.TryReadBlock(reader, out record))
{
throw new ZipArchiveException("Zip64EOCDNotWhereExpected");
}
if (record.NumberOfEntriesTotal > long.MaxValue)
{
throw new ZipArchiveException("FieldTooBigNumEntries");
}
if (record.OffsetOfCentralDirectory > long.MaxValue)
{
throw new ZipArchiveException("FieldTooBigOffsetToCD");
}
if (record.NumberOfEntriesTotal != record.NumberOfEntriesOnThisDisk)
{
throw new ZipArchiveException("SplitSpanned");
}
expectedNumberOfEntries = (long)record.NumberOfEntriesTotal;
centralDirectoryStart = (long)record.OffsetOfCentralDirectory;
}
}
if (centralDirectoryStart > stream.Length)
{
throw new ZipArchiveException("FieldTooBigOffsetToCD");
}
}
catch (EndOfStreamException ex)
{
throw new ZipArchiveException("CDCorrupt", ex);
}
catch (IOException ex)
{
throw new ZipArchiveException("CDCorrupt", ex);
}
}