/// <summary>
/// Search for and read the central directory of a zip file filling the entries
/// array. This is called exactly once by the constructors.
/// </summary>
/// <exception cref="System.IO.IOException">
/// An i/o error occurs.
/// </exception>
/// <exception cref="NTDLS.IO.Compression.Zip.ZipException">
/// The central directory is malformed or cannot be found
/// </exception>
void ReadEntries()
{
// Search for the End Of Central Directory. When a zip comment is
// present the directory may start earlier.
//
// TODO: The search is limited to 64K which is the maximum size of a trailing comment field to aid speed.
// This should be compatible with both SFX and ZIP files but has only been tested for Zip files
// Need to confirm this is valid in all cases.
// Could also speed this up by reading memory in larger blocks.
if (baseStream.CanSeek == false)
{
throw new ZipException("ZipFile stream must be seekable");
}
long locatedCentralDirOffset = LocateBlockWithSignature(ZipConstants.ENDSIG, baseStream.Length, ZipConstants.ENDHDR, 0xffff);
if (locatedCentralDirOffset < 0)
{
throw new ZipException("Cannot find central directory");
}
int thisDiskNumber = ReadLeShort();
int startCentralDirDisk = ReadLeShort();
int entriesForThisDisk = ReadLeShort();
int entriesForWholeCentralDir = ReadLeShort();
int centralDirSize = ReadLeInt();
int offsetOfCentralDir = ReadLeInt();
int commentSize = ReadLeShort();
byte[] zipComment = new byte[commentSize];
baseStream.Read(zipComment, 0, zipComment.Length);
comment = ZipConstants.ConvertToString(zipComment);
/* Its seems possible that this is too strict, more digging required.
* if (thisDiskNumber != 0 || startCentralDirDisk != 0 || entriesForThisDisk != entriesForWholeCentralDir) {
* throw new ZipException("Spanned archives are not currently handled");
* }
*/
entries = new ZipEntry[entriesForWholeCentralDir];
// SFX support, find the offset of the first entry vis the start of the stream
// This applies to Zip files that are appended to the end of the SFX stub.
// Zip files created by some archivers have the offsets altered to reflect the true offsets
// and so dont require any adjustment here...
if (offsetOfCentralDir < locatedCentralDirOffset - (4 + centralDirSize))
{
offsetOfFirstEntry = locatedCentralDirOffset - (4 + centralDirSize + offsetOfCentralDir);
if (offsetOfFirstEntry <= 0)
{
throw new ZipException("Invalid SFX file");
}
}
baseStream.Seek(offsetOfFirstEntry + offsetOfCentralDir, SeekOrigin.Begin);
for (int i = 0; i < entriesForThisDisk; i++)
{
if (ReadLeInt() != ZipConstants.CENSIG)
{
throw new ZipException("Wrong Central Directory signature");
}
int versionMadeBy = ReadLeShort();
int versionToExtract = ReadLeShort();
int bitFlags = ReadLeShort();
int method = ReadLeShort();
int dostime = ReadLeInt();
int crc = ReadLeInt();
int csize = ReadLeInt();
int size = ReadLeInt();
int nameLen = ReadLeShort();
int extraLen = ReadLeShort();
int commentLen = ReadLeShort();
int diskStartNo = ReadLeShort(); // Not currently used
int internalAttributes = ReadLeShort(); // Not currently used
int externalAttributes = ReadLeInt();
int offset = ReadLeInt();
byte[] buffer = new byte[Math.Max(nameLen, commentLen)];
baseStream.Read(buffer, 0, nameLen);
string name = ZipConstants.ConvertToString(buffer, nameLen);
ZipEntry entry = new ZipEntry(name, versionToExtract, versionMadeBy);
entry.CompressionMethod = (CompressionMethod)method;
entry.Crc = crc & 0xffffffffL;
entry.Size = size & 0xffffffffL;
entry.CompressedSize = csize & 0xffffffffL;
entry.Flags = bitFlags;
entry.DosTime = (uint)dostime;
if (extraLen > 0)
{
byte[] extra = new byte[extraLen];
baseStream.Read(extra, 0, extraLen);
entry.ExtraData = extra;
}
if (commentLen > 0)
{
baseStream.Read(buffer, 0, commentLen);
entry.Comment = ZipConstants.ConvertToString(buffer, commentLen);
}
entry.ZipFileIndex = i;
entry.Offset = offset;
entry.ExternalFileAttributes = externalAttributes;
entries[i] = entry;
}
}
/// <summary>
/// Advances to the next entry in the archive
/// </summary>
/// <returns>
/// The next <see cref="ZipEntry">entry</see> in the archive or null if there are no more entries.
/// </returns>
/// <remarks>
/// If the previous entry is still open <see cref="CloseEntry">CloseEntry</see> is called.
/// </remarks>
/// <exception cref="InvalidOperationException">
/// Input stream is closed
/// </exception>
/// <exception cref="ZipException">
/// Password is not set, password is invalid, compression method is invalid,
/// version required to extract is not supported
/// </exception>
public ZipEntry GetNextEntry()
{
if (crc == null)
{
throw new InvalidOperationException("Closed.");
}
if (entry != null)
{
CloseEntry();
}
int header = inputBuffer.ReadLeInt();
if (header == ZipConstants.CENSIG ||
header == ZipConstants.ENDSIG ||
header == ZipConstants.CENDIGITALSIG ||
header == ZipConstants.CENSIG64)
{
// No more individual entries exist
Close();
return(null);
}
// -jr- 07-Dec-2003 Ignore spanning temporary signatures if found
// SPANNINGSIG is same as descriptor signature and is untested as yet.
if (header == ZipConstants.SPANTEMPSIG || header == ZipConstants.SPANNINGSIG)
{
header = inputBuffer.ReadLeInt();
}
if (header != ZipConstants.LOCSIG)
{
throw new ZipException("Wrong Local header signature: 0x" + String.Format("{0:X}", header));
}
short versionRequiredToExtract = (short)inputBuffer.ReadLeShort();
flags = inputBuffer.ReadLeShort();
method = inputBuffer.ReadLeShort();
uint dostime = (uint)inputBuffer.ReadLeInt();
int crc2 = inputBuffer.ReadLeInt();
csize = inputBuffer.ReadLeInt();
size = inputBuffer.ReadLeInt();
int nameLen = inputBuffer.ReadLeShort();
int extraLen = inputBuffer.ReadLeShort();
bool isCrypted = (flags & 1) == 1;
byte[] buffer = new byte[nameLen];
inputBuffer.ReadRawBuffer(buffer);
string name = ZipConstants.ConvertToString(buffer);
entry = new ZipEntry(name, versionRequiredToExtract);
entry.Flags = flags;
if (method == (int)CompressionMethod.Stored && (!isCrypted && csize != size || (isCrypted && csize - ZipConstants.CRYPTO_HEADER_SIZE != size)))
{
throw new ZipException("Stored, but compressed != uncompressed");
}
if (method != (int)CompressionMethod.Stored && method != (int)CompressionMethod.Deflated)
{
throw new ZipException("Unknown compression method " + method);
}
entry.CompressionMethod = (CompressionMethod)method;
if ((flags & 8) == 0)
{
entry.Crc = crc2 & 0xFFFFFFFFL;
entry.Size = size & 0xFFFFFFFFL;
entry.CompressedSize = csize & 0xFFFFFFFFL;
}
else
{
// This allows for GNU, WinZip and possibly other archives, the PKZIP spec says these are zero
// under these circumstances.
if (crc2 != 0)
{
entry.Crc = crc2 & 0xFFFFFFFFL;
}
if (size != 0)
{
entry.Size = size & 0xFFFFFFFFL;
}
if (csize != 0)
{
entry.CompressedSize = csize & 0xFFFFFFFFL;
}
}
entry.DosTime = dostime;
if (extraLen > 0)
{
byte[] extra = new byte[extraLen];
inputBuffer.ReadRawBuffer(extra);
entry.ExtraData = extra;
}
internalReader = new ReaderDelegate(InitialRead);
return(entry);
}
