/// <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="Sirona.Utilities.Compression.Engine.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 pos = baseStream.Length - ZipConstants.ENDHDR;
if (pos <= 0)
{
throw new ZipException("File is too small to be a Zip file");
}
long giveUpMarker = Math.Max(pos - 0x10000, 0);
do
{
if (pos < giveUpMarker)
{
throw new ZipException("central directory not found, probably not a zip file");
}
baseStream.Seek(pos--, SeekOrigin.Begin);
} while (ReadLeInt() != ZipConstants.ENDSIG);
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];
baseStream.Seek(offsetOfCentralDir, SeekOrigin.Begin);
for (int i = 0; i < entriesForWholeCentralDir; 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();
}
if (this.cryptbuffer != null)
{
if (avail == 0 && inf.RemainingInput != 0)
{
avail = inf.RemainingInput - 16;
inf.Reset();
}
baseInputStream.Position -= this.len;
baseInputStream.Read(this.buf, 0, this.len);
}
if (avail <= 0)
{
FillBuf(ZipConstants.LOCHDR);
}
int header = 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 = ReadLeInt();
}
if (header != ZipConstants.LOCSIG)
{
throw new ZipException("Wrong Local header signature: 0x" + String.Format("{0:X}", header));
}
short versionRequiredToExtract = (short)ReadLeShort();
flags = ReadLeShort();
method = ReadLeShort();
uint dostime = (uint)ReadLeInt();
int crc2 = ReadLeInt();
csize = ReadLeInt();
size = ReadLeInt();
int nameLen = ReadLeShort();
int extraLen = ReadLeShort();
bool isCrypted = (flags & 1) == 1;
byte[] buffer = new byte[nameLen];
ReadFully(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;
BufferReadSize = 0;
}
else
{
if (isCrypted)
{
BufferReadSize = 1;
}
else
{
BufferReadSize = 0;
}
// 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];
ReadFully(extra);
entry.ExtraData = extra;
}
// TODO How to handle this?
// This library cannot handle versions greater than 20
// Throwing an exception precludes getting at later possibly useable entries.
// Could also skip this entry entirely
// Letting it slip past here isnt so great as it wont work
if (versionRequiredToExtract > 20)
{
throw new ZipException("Libray cannot extract this entry version required (" + versionRequiredToExtract.ToString() + ")");
}
// test for encryption
if (isCrypted)
{
if (password == null)
{
throw new ZipException("No password set.");
}
InitializePassword(password);
cryptbuffer = new byte[ZipConstants.CRYPTO_HEADER_SIZE];
ReadFully(cryptbuffer);
DecryptBlock(cryptbuffer, 0, cryptbuffer.Length);
if ((flags & 8) == 0)
{
if (cryptbuffer[ZipConstants.CRYPTO_HEADER_SIZE - 1] != (byte)(crc2 >> 24))
{
throw new ZipException("Invalid password");
}
}
else
{
if (cryptbuffer[ZipConstants.CRYPTO_HEADER_SIZE - 1] != (byte)((dostime >> 8) & 0xff))
{
throw new ZipException("Invalid password");
}
}
if (csize >= ZipConstants.CRYPTO_HEADER_SIZE)
{
csize -= ZipConstants.CRYPTO_HEADER_SIZE;
}
}
else
{
cryptbuffer = null;
}
if (method == (int)CompressionMethod.Deflated && avail > 0)
{
System.Array.Copy(buf, len - (int)avail, buf, 0, (int)avail);
len = (int)avail;
avail = 0;
if (isCrypted)
{
DecryptBlock(buf, 0, Math.Min((int)csize, len));
}
inf.SetInput(buf, 0, len);
}
return(entry);
}