/// <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.CentralHeaderSignature ||
header == ZipConstants.EndOfCentralDirectorySignature ||
header == ZipConstants.CentralHeaderDigitalSignature ||
header == ZipConstants.ArchiveExtraDataSignature ||
header == ZipConstants.Zip64CentralFileHeaderSignature) {
// No more individual entries exist
Close();
return null;
}
// -jr- 07-Dec-2003 Ignore spanning temporary signatures if found
// Spanning signature is same as descriptor signature and is untested as yet.
if ( (header == ZipConstants.SpanningTempSignature) || (header == ZipConstants.SpanningSignature) ) {
header = inputBuffer.ReadLeInt();
}
if (header != ZipConstants.LocalHeaderSignature) {
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.ConvertToStringExt(flags, buffer);
entry = new ZipEntry(name, versionRequiredToExtract);
entry.Flags = flags;
entry.CompressionMethod = (CompressionMethod)method;
if ((flags & 8) == 0) {
entry.Crc = crc2 & 0xFFFFFFFFL;
entry.Size = size & 0xFFFFFFFFL;
entry.CompressedSize = csize & 0xFFFFFFFFL;
entry.CryptoCheckValue = (byte)((crc2 >> 24) & 0xff);
} else {
// This allows for GNU, WinZip and possibly other archives, the PKZIP spec
// says these values 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.CryptoCheckValue = (byte)((dostime >> 8) & 0xff);
}
entry.DosTime = dostime;
// If local header requires Zip64 is true then the extended header should contain
// both values.
// Handle extra data if present. This can set/alter some fields of the entry.
if (extraLen > 0) {
byte[] extra = new byte[extraLen];
inputBuffer.ReadRawBuffer(extra);
entry.ExtraData = extra;
}
entry.ProcessExtraData(true);
if ( entry.CompressedSize >= 0 ) {
csize = entry.CompressedSize;
}
if ( entry.Size >= 0 ) {
size = entry.Size;
}
if (method == (int)CompressionMethod.Stored && (!isCrypted && csize != size || (isCrypted && csize - ZipConstants.CryptoHeaderSize != size))) {
throw new ZipException("Stored, but compressed != uncompressed");
}
// Determine how to handle reading of data if this is attempted.
if (entry.IsCompressionMethodSupported()) {
internalReader = new ReadDataHandler(InitialRead);
} else {
internalReader = new ReadDataHandler(ReadingNotSupported);
}
return entry;
}
/// <summary>
/// Test a local header against that provided from the central directory
/// </summary>
/// <param name="entry">
/// The entry to test against
/// </param>
/// <param name="tests">The type of <see cref="HeaderTest">tests</see> to carry out.</param>
/// <returns>The offset of the entries data in the file</returns>
long TestLocalHeader(ZipEntry entry, HeaderTest tests)
{
lock(baseStream_)
{
bool testHeader = (tests & HeaderTest.Header) != 0;
bool testData = (tests & HeaderTest.Extract) != 0;
baseStream_.Seek(offsetOfFirstEntry + entry.Offset, SeekOrigin.Begin);
if ((int)ReadLEUint() != ZipConstants.LocalHeaderSignature) {
throw new ZipException(string.Format("Wrong local header signature @{0:X}", offsetOfFirstEntry + entry.Offset));
}
short extractVersion = ( short )ReadLEUshort();
short localFlags = ( short )ReadLEUshort();
short compressionMethod = ( short )ReadLEUshort();
short fileTime = ( short )ReadLEUshort();
short fileDate = ( short )ReadLEUshort();
uint crcValue = ReadLEUint();
long compressedSize = ReadLEUint();
long size = ReadLEUint();
int storedNameLength = ReadLEUshort();
int extraDataLength = ReadLEUshort();
byte[] nameData = new byte[storedNameLength];
StreamUtils.ReadFully(baseStream_, nameData);
byte[] extraData = new byte[extraDataLength];
StreamUtils.ReadFully(baseStream_, extraData);
ZipExtraData localExtraData = new ZipExtraData(extraData);
// Extra data / zip64 checks
if (localExtraData.Find(1))
{
// TODO Check for tag values being distinct.. Multiple zip64 tags means what?
// Zip64 extra data but 'extract version' is too low
if (extractVersion < ZipConstants.VersionZip64)
{
throw new ZipException(
string.Format("Extra data contains Zip64 information but version {0}.{1} is not high enough",
extractVersion / 10, extractVersion % 10));
}
// Zip64 extra data but size fields dont indicate its required.
if (((uint)size != uint.MaxValue) && ((uint)compressedSize != uint.MaxValue))
{
throw new ZipException("Entry sizes not correct for Zip64");
}
size = localExtraData.ReadLong();
compressedSize = localExtraData.ReadLong();
if ((localFlags & (int)GeneralBitFlags.Descriptor) != 0)
{
// These may be valid if patched later
if ( (size != -1) && (size != entry.Size)) {
throw new ZipException("Size invalid for descriptor");
}
if ((compressedSize != -1) && (compressedSize != entry.CompressedSize)) {
throw new ZipException("Compressed size invalid for descriptor");
}
}
}
else
{
// No zip64 extra data but entry requires it.
if ((extractVersion >= ZipConstants.VersionZip64) &&
(((uint)size == uint.MaxValue) || ((uint)compressedSize == uint.MaxValue)))
{
throw new ZipException("Required Zip64 extended information missing");
}
}
if ( testData ) {
if ( entry.IsFile ) {
if ( !entry.IsCompressionMethodSupported() ) {
throw new ZipException("Compression method not supported");
}
if ( (extractVersion > ZipConstants.VersionMadeBy)
|| ((extractVersion > 20) && (extractVersion < ZipConstants.VersionZip64)) ) {
throw new ZipException(string.Format("Version required to extract this entry not supported ({0})", extractVersion));
}
if ( (localFlags & ( int )(GeneralBitFlags.Patched | GeneralBitFlags.StrongEncryption | GeneralBitFlags.EnhancedCompress | GeneralBitFlags.HeaderMasked)) != 0 ) {
throw new ZipException("The library does not support the zip version required to extract this entry");
}
}
}
if (testHeader)
{
if ((extractVersion <= 63) && // Ignore later versions as we dont know about them..
(extractVersion != 10) &&
(extractVersion != 11) &&
(extractVersion != 20) &&
(extractVersion != 21) &&
(extractVersion != 25) &&
(extractVersion != 27) &&
(extractVersion != 45) &&
(extractVersion != 46) &&
(extractVersion != 50) &&
(extractVersion != 51) &&
(extractVersion != 52) &&
(extractVersion != 61) &&
(extractVersion != 62) &&
(extractVersion != 63)
)
{
throw new ZipException(string.Format("Version required to extract this entry is invalid ({0})", extractVersion));
}
// Local entry flags dont have reserved bit set on.
if ((localFlags & (int)(GeneralBitFlags.ReservedPKware4 | GeneralBitFlags.ReservedPkware14 | GeneralBitFlags.ReservedPkware15)) != 0)
{
throw new ZipException("Reserved bit flags cannot be set.");
}
// Encryption requires extract version >= 20
if (((localFlags & (int)GeneralBitFlags.Encrypted) != 0) && (extractVersion < 20))
{
throw new ZipException(string.Format("Version required to extract this entry is too low for encryption ({0})", extractVersion));
}
// Strong encryption requires encryption flag to be set and extract version >= 50.
if ((localFlags & (int)GeneralBitFlags.StrongEncryption) != 0)
{
if ((localFlags & (int)GeneralBitFlags.Encrypted) == 0)
{
throw new ZipException("Strong encryption flag set but encryption flag is not set");
}
if (extractVersion < 50)
{
throw new ZipException(string.Format("Version required to extract this entry is too low for encryption ({0})", extractVersion));
}
}
// Patched entries require extract version >= 27
if (((localFlags & (int)GeneralBitFlags.Patched) != 0) && (extractVersion < 27))
{
throw new ZipException(string.Format("Patched data requires higher version than ({0})", extractVersion));
}
// Central header flags match local entry flags.
if (localFlags != entry.Flags)
{
throw new ZipException("Central header/local header flags mismatch");
}
// Central header compression method matches local entry
if (entry.CompressionMethod != (CompressionMethod)compressionMethod)
{
throw new ZipException("Central header/local header compression method mismatch");
}
if (entry.Version != extractVersion)
{
throw new ZipException("Extract version mismatch");
}
// Strong encryption and extract version match
if ((localFlags & (int)GeneralBitFlags.StrongEncryption) != 0)
{
if (extractVersion < 62)
{
throw new ZipException("Strong encryption flag set but version not high enough");
}
}
if ((localFlags & (int)GeneralBitFlags.HeaderMasked) != 0)
{
if ((fileTime != 0) || (fileDate != 0))
{
throw new ZipException("Header masked set but date/time values non-zero");
}
}
if ((localFlags & (int)GeneralBitFlags.Descriptor) == 0)
{
if (crcValue != (uint)entry.Crc)
{
throw new ZipException("Central header/local header crc mismatch");
}
}
// Crc valid for empty entry.
// This will also apply to streamed entries where size isnt known and the header cant be patched
if ((size == 0) && (compressedSize == 0))
{
if (crcValue != 0)
{
throw new ZipException("Invalid CRC for empty entry");
}
}
// TODO: make test more correct... can't compare lengths as was done originally as this can fail for MBCS strings
// Assuming a code page at this point is not valid? Best is to store the name length in the ZipEntry probably
if (entry.Name.Length > storedNameLength)
{
throw new ZipException("File name length mismatch");
}
// Name data has already been read convert it and compare.
string localName = ZipConstants.ConvertToStringExt(localFlags, nameData);
// Central directory and local entry name match
if (localName != entry.Name)
{
throw new ZipException("Central header and local header file name mismatch");
}
// Directories have zero actual size but can have compressed size
if (entry.IsDirectory)
{
if (size > 0)
{
throw new ZipException("Directory cannot have size");
}
// There may be other cases where the compressed size can be greater than this?
// If so until details are known we will be strict.
if (entry.IsCrypted)
{
if (compressedSize > ZipConstants.CryptoHeaderSize + 2)
{
throw new ZipException("Directory compressed size invalid");
}
}
else if (compressedSize > 2)
{
// When not compressed the directory size can validly be 2 bytes
// if the true size wasnt known when data was originally being written.
// NOTE: Versions of the library 0.85.4 and earlier always added 2 bytes
throw new ZipException("Directory compressed size invalid");
}
}
if (!ZipNameTransform.IsValidName(localName, true))
{
throw new ZipException("Name is invalid");
}
}
// Tests that apply to both data and header.
// Size can be verified only if it is known in the local header.
// it will always be known in the central header.
if (((localFlags & (int)GeneralBitFlags.Descriptor) == 0) ||
((size > 0) || (compressedSize > 0))) {
if (size != entry.Size) {
throw new ZipException(
string.Format("Size mismatch between central header({0}) and local header({1})",
entry.Size, size));
}
if (compressedSize != entry.CompressedSize) {
throw new ZipException(
string.Format("Compressed size mismatch between central header({0}) and local header({1})",
entry.CompressedSize, compressedSize));
}
}
int extraLength = storedNameLength + extraDataLength;
return offsetOfFirstEntry + entry.Offset + ZipConstants.LocalHeaderBaseSize + extraLength;
}
}