|
public static TryReadBlock ( BinaryReader reader, |
||
| reader | BinaryReader | |
| eocdBlock | ||
| return | bool | |
// 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 backwards almost to the beginning of the EOCD, one byte after where the signature would be
// located if the EOCD had the minimum possible size (no file zip comment)
_archiveStream.Seek(-ZipEndOfCentralDirectoryBlock.SizeOfBlockWithoutSignature, SeekOrigin.End);
// If the EOCD has the minimum possible size (no zip file comment), then exactly the previous 4 bytes will contain the signature
// But if the EOCD has max possible size, the signature should be found somewhere in the previous 64K + 4 bytes
if (!ZipHelper.SeekBackwardsToSignature(_archiveStream,
ZipEndOfCentralDirectoryBlock.SignatureConstant,
ZipEndOfCentralDirectoryBlock.ZipFileCommentMaxLength + ZipEndOfCentralDirectoryBlock.SignatureSize))
{
throw new InvalidDataException(SR.EOCDNotFound);
}
long eocdStart = _archiveStream.Position;
// read the EOCD
ZipEndOfCentralDirectoryBlock eocd;
bool 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;
}
TryReadZip64EndOfCentralDirectory(eocd, eocdStart);
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);
}
}
//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);
}
long eocdStart = _archiveStream.Position;
//read the EOCD
ZipEndOfCentralDirectoryBlock eocd;
bool 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;
bool 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 > (ulong)long.MaxValue)
{
throw new InvalidDataException(SR.FieldTooBigOffsetToZip64EOCD);
}
long zip64EOCDOffset = (long)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 > (ulong)long.MaxValue)
{
throw new InvalidDataException(SR.FieldTooBigNumEntries);
}
if (record.OffsetOfCentralDirectory > (ulong)long.MaxValue)
{
throw new InvalidDataException(SR.FieldTooBigOffsetToCD);
}
if (record.NumberOfEntriesTotal != record.NumberOfEntriesOnThisDisk)
{
throw new InvalidDataException(SR.SplitSpanned);
}
_expectedNumberOfEntries = (long)record.NumberOfEntriesTotal;
_centralDirectoryStart = (long)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);
}
}
private void ReadEndOfCentralDirectory()
{
ZipEndOfCentralDirectoryBlock zipEndOfCentralDirectoryBlock;
Zip64EndOfCentralDirectoryLocator zip64EndOfCentralDirectoryLocator;
Zip64EndOfCentralDirectoryRecord zip64EndOfCentralDirectoryRecord;
try
{
this._archiveStream.Seek((long)-18, SeekOrigin.End);
if (!ZipHelper.SeekBackwardsToSignature(this._archiveStream, 101010256))
{
throw new InvalidDataException(Messages.EOCDNotFound);
}
long position = this._archiveStream.Position;
ZipEndOfCentralDirectoryBlock.TryReadBlock(this._archiveReader, out zipEndOfCentralDirectoryBlock);
if (zipEndOfCentralDirectoryBlock.NumberOfThisDisk != zipEndOfCentralDirectoryBlock.NumberOfTheDiskWithTheStartOfTheCentralDirectory)
{
throw new InvalidDataException(Messages.SplitSpanned);
}
this._numberOfThisDisk = zipEndOfCentralDirectoryBlock.NumberOfThisDisk;
this._centralDirectoryStart = (long)zipEndOfCentralDirectoryBlock.OffsetOfStartOfCentralDirectoryWithRespectToTheStartingDiskNumber;
if (zipEndOfCentralDirectoryBlock.NumberOfEntriesInTheCentralDirectory != zipEndOfCentralDirectoryBlock.NumberOfEntriesInTheCentralDirectoryOnThisDisk)
{
throw new InvalidDataException(Messages.SplitSpanned);
}
this._expectedNumberOfEntries = (long)zipEndOfCentralDirectoryBlock.NumberOfEntriesInTheCentralDirectory;
if (this._mode == ZipArchiveMode.Update)
{
this._archiveComment = zipEndOfCentralDirectoryBlock.ArchiveComment;
}
if (zipEndOfCentralDirectoryBlock.NumberOfThisDisk == 65535 || zipEndOfCentralDirectoryBlock.OffsetOfStartOfCentralDirectoryWithRespectToTheStartingDiskNumber == -1 || zipEndOfCentralDirectoryBlock.NumberOfEntriesInTheCentralDirectory == 65535)
{
this._archiveStream.Seek(position - (long)16, SeekOrigin.Begin);
if (ZipHelper.SeekBackwardsToSignature(this._archiveStream, 117853008))
{
Zip64EndOfCentralDirectoryLocator.TryReadBlock(this._archiveReader, out zip64EndOfCentralDirectoryLocator);
if (zip64EndOfCentralDirectoryLocator.OffsetOfZip64EOCD > 9223372036854775807L)
{
throw new InvalidDataException(Messages.FieldTooBigOffsetToZip64EOCD);
}
long offsetOfZip64EOCD = (long)zip64EndOfCentralDirectoryLocator.OffsetOfZip64EOCD;
this._archiveStream.Seek(offsetOfZip64EOCD, SeekOrigin.Begin);
if (!Zip64EndOfCentralDirectoryRecord.TryReadBlock(this._archiveReader, out zip64EndOfCentralDirectoryRecord))
{
throw new InvalidDataException(Messages.Zip64EOCDNotWhereExpected);
}
this._numberOfThisDisk = zip64EndOfCentralDirectoryRecord.NumberOfThisDisk;
if (zip64EndOfCentralDirectoryRecord.NumberOfEntriesTotal > 9223372036854775807L)
{
throw new InvalidDataException(Messages.FieldTooBigNumEntries);
}
if (zip64EndOfCentralDirectoryRecord.OffsetOfCentralDirectory > 9223372036854775807L)
{
throw new InvalidDataException(Messages.FieldTooBigOffsetToCD);
}
if (zip64EndOfCentralDirectoryRecord.NumberOfEntriesTotal != zip64EndOfCentralDirectoryRecord.NumberOfEntriesOnThisDisk)
{
throw new InvalidDataException(Messages.SplitSpanned);
}
this._expectedNumberOfEntries = (long)zip64EndOfCentralDirectoryRecord.NumberOfEntriesTotal;
this._centralDirectoryStart = (long)zip64EndOfCentralDirectoryRecord.OffsetOfCentralDirectory;
}
}
if (this._centralDirectoryStart > this._archiveStream.Length)
{
throw new InvalidDataException(Messages.FieldTooBigOffsetToCD);
}
}
catch (EndOfStreamException endOfStreamException)
{
throw new InvalidDataException(Messages.CDCorrupt, endOfStreamException);
}
catch (IOException oException)
{
throw new InvalidDataException(Messages.CDCorrupt, oException);
}
}