Esempio n. 1
0
 public Stream Compress(Stream fileStream,string fullName)
 {
     using (var zip = new ZipFile())
     {
         zip.AddEntry(fullName, fileStream);
         Stream zipStream = new MemoryStream();
         zip.Save(zipStream);
         return zipStream;
     }
 }
Esempio n. 2
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        private static void ReadZipFileComment(ZipFile zf)
        {
            // read the comment here
            byte[] block = new byte[2];
            zf.ReadStream.Read(block, 0, block.Length);

            Int16 commentLength = (short)(block[0] + block[1] * 256);
            if (commentLength > 0)
            {
                block = new byte[commentLength];
                zf.ReadStream.Read(block, 0, block.Length);

                // workitem 10392 - prefer ProvisionalAlternateEncoding,
                // first.  The fix for workitem 6513 tried to use UTF8
                // only as necessary, but that is impossible to test
                // for, in this direction. There's no way to know what
                // characters the already-encoded bytes refer
                // to. Therefore, must do what the user tells us.

                string s1 = zf.AlternateEncoding.GetString(block, 0, block.Length);
                zf.Comment = s1;
            }
        }
Esempio n. 3
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        private static void ReadCentralDirectoryFooter(ZipFile zf)
        {
            Stream s = zf.ReadStream;
            int signature = Zephyr.Utils.Ionic.Zip.SharedUtilities.ReadSignature(s);

            byte[] block = null;
            int j = 0;
            if (signature == ZipConstants.Zip64EndOfCentralDirectoryRecordSignature)
            {
                // We have a ZIP64 EOCD
                // This data block is 4 bytes sig, 8 bytes size, 44 bytes fixed data,
                // followed by a variable-sized extension block.  We have read the sig already.
                // 8 - datasize (64 bits)
                // 2 - version made by
                // 2 - version needed to extract
                // 4 - number of this disk
                // 4 - number of the disk with the start of the CD
                // 8 - total number of entries in the CD on this disk
                // 8 - total number of entries in the CD
                // 8 - size of the CD
                // 8 - offset of the CD
                // -----------------------
                // 52 bytes

                block = new byte[8 + 44];
                s.Read(block, 0, block.Length);

                Int64 DataSize = BitConverter.ToInt64(block, 0);  // == 44 + the variable length

                if (DataSize < 44)
                    throw new ZipException("Bad size in the ZIP64 Central Directory.");

                zf._versionMadeBy = BitConverter.ToUInt16(block, j);
                j += 2;
                zf._versionNeededToExtract = BitConverter.ToUInt16(block, j);
                j += 2;
                zf._diskNumberWithCd = BitConverter.ToUInt32(block, j);
                j += 2;

                //zf._diskNumberWithCd++; // hack!!

                // read the extended block
                block = new byte[DataSize - 44];
                s.Read(block, 0, block.Length);
                // discard the result

                signature = Zephyr.Utils.Ionic.Zip.SharedUtilities.ReadSignature(s);
                if (signature != ZipConstants.Zip64EndOfCentralDirectoryLocatorSignature)
                    throw new ZipException("Inconsistent metadata in the ZIP64 Central Directory.");

                block = new byte[16];
                s.Read(block, 0, block.Length);
                // discard the result

                signature = Zephyr.Utils.Ionic.Zip.SharedUtilities.ReadSignature(s);
            }

            // Throw if this is not a signature for "end of central directory record"
            // This is a sanity check.
            if (signature != ZipConstants.EndOfCentralDirectorySignature)
            {
                s.Seek(-4, SeekOrigin.Current);
                throw new BadReadException(String.Format("Bad signature ({0:X8}) at position 0x{1:X8}",
                                                         signature, s.Position));
            }

            // read the End-of-Central-Directory-Record
            block = new byte[16];
            zf.ReadStream.Read(block, 0, block.Length);

            // off sz  data
            // -------------------------------------------------------
            //  0   4  end of central dir signature (0x06054b50)
            //  4   2  number of this disk
            //  6   2  number of the disk with start of the central directory
            //  8   2  total number of entries in the  central directory on this disk
            // 10   2  total number of entries in  the central directory
            // 12   4  size of the central directory
            // 16   4  offset of start of central directory with respect to the starting disk number
            // 20   2  ZIP file comment length
            // 22  ??  ZIP file comment

            if (zf._diskNumberWithCd == 0)
            {
                zf._diskNumberWithCd = BitConverter.ToUInt16(block, 2);
                //zf._diskNumberWithCd++; // hack!!
            }

            // read the comment here
            ReadZipFileComment(zf);
        }
Esempio n. 4
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        // build the TOC by reading each entry in the file.
        private static void ReadIntoInstance_Orig(ZipFile zf)
        {
            zf.OnReadStarted();
            //zf._entries = new System.Collections.Generic.List<ZipEntry>();
            zf._entries = new System.Collections.Generic.Dictionary<String,ZipEntry>();

            ZipEntry e;
            if (zf.Verbose)
                if (zf.Name == null)
                    zf.StatusMessageTextWriter.WriteLine("Reading zip from stream...");
                else
                    zf.StatusMessageTextWriter.WriteLine("Reading zip {0}...", zf.Name);

            // work item 6647:  PK00 (packed to removable disk)
            bool firstEntry = true;
            ZipContainer zc = new ZipContainer(zf);
            while ((e = ZipEntry.ReadEntry(zc, firstEntry)) != null)
            {
                if (zf.Verbose)
                    zf.StatusMessageTextWriter.WriteLine("  {0}", e.FileName);

                zf._entries.Add(e.FileName,e);
                firstEntry = false;
            }

            // read the zipfile's central directory structure here.
            // workitem 9912
            // But, because it may be corrupted, ignore errors.
            try
            {
                ZipEntry de;
                // in lieu of hashset, use a dictionary
                var previouslySeen = new Dictionary<String,Object>();
                while ((de = ZipEntry.ReadDirEntry(zf, previouslySeen)) != null)
                {
                    // Housekeeping: Since ZipFile exposes ZipEntry elements in the enumerator,
                    // we need to copy the comment that we grab from the ZipDirEntry
                    // into the ZipEntry, so the application can access the comment.
                    // Also since ZipEntry is used to Write zip files, we need to copy the
                    // file attributes to the ZipEntry as appropriate.
                    ZipEntry e1 = zf._entries[de.FileName];
                    if (e1 != null)
                    {
                        e1._Comment = de.Comment;
                        if (de.IsDirectory) e1.MarkAsDirectory();
                    }
                    previouslySeen.Add(de.FileName,null); // to prevent dupes
                }

                // workitem 8299
                if (zf._locEndOfCDS > 0)
                    zf.ReadStream.Seek(zf._locEndOfCDS, SeekOrigin.Begin);

                ReadCentralDirectoryFooter(zf);

                if (zf.Verbose && !String.IsNullOrEmpty(zf.Comment))
                    zf.StatusMessageTextWriter.WriteLine("Zip file Comment: {0}", zf.Comment);
            }
            catch (ZipException) { }
            catch (IOException) { }

            zf.OnReadCompleted();
        }
Esempio n. 5
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        private static void ReadCentralDirectory(ZipFile zf)
        {
            // We must have the central directory footer record, in order to properly
            // read zip dir entries from the central directory.  This because the logic
            // knows when to open a spanned file when the volume number for the central
            // directory differs from the volume number for the zip entry.  The
            // _diskNumberWithCd was set when originally finding the offset for the
            // start of the Central Directory.

            // workitem 9214
            bool inputUsesZip64 = false;
            ZipEntry de;
            // in lieu of hashset, use a dictionary
            var previouslySeen = new Dictionary<String,object>();
            while ((de = ZipEntry.ReadDirEntry(zf, previouslySeen)) != null)
            {
                de.ResetDirEntry();
                zf.OnReadEntry(true, null);

                if (zf.Verbose)
                    zf.StatusMessageTextWriter.WriteLine("entry {0}", de.FileName);

                zf._entries.Add(de.FileName,de);

                // workitem 9214
                if (de._InputUsesZip64) inputUsesZip64 = true;
                previouslySeen.Add(de.FileName, null); // to prevent dupes
            }

            // workitem 9214; auto-set the zip64 flag
            if (inputUsesZip64) zf.UseZip64WhenSaving = Zip64Option.Always;

            // workitem 8299
            if (zf._locEndOfCDS > 0)
                zf.ReadStream.Seek(zf._locEndOfCDS, SeekOrigin.Begin);

            ReadCentralDirectoryFooter(zf);

            if (zf.Verbose && !String.IsNullOrEmpty(zf.Comment))
                zf.StatusMessageTextWriter.WriteLine("Zip file Comment: {0}", zf.Comment);

            // We keep the read stream open after reading.

            if (zf.Verbose)
                zf.StatusMessageTextWriter.WriteLine("read in {0} entries.", zf._entries.Count);

            zf.OnReadCompleted();
        }
Esempio n. 6
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        private static void Zip64SeekToCentralDirectory(ZipFile zf)
        {
            Stream s = zf.ReadStream;
            byte[] block = new byte[16];

            // seek back to find the ZIP64 EoCD.
            // I think this might not work for .NET CF ?
            s.Seek(-40, SeekOrigin.Current);
            s.Read(block, 0, 16);

            Int64 offset64 = BitConverter.ToInt64(block, 8);
            zf._OffsetOfCentralDirectory = 0xFFFFFFFF;
            zf._OffsetOfCentralDirectory64 = offset64;
            // change for workitem 8098
            s.Seek(offset64, SeekOrigin.Begin);
            //zf.SeekFromOrigin(Offset64);

            uint datum = (uint)Zephyr.Utils.Ionic.Zip.SharedUtilities.ReadInt(s);
            if (datum != ZipConstants.Zip64EndOfCentralDirectoryRecordSignature)
                throw new BadReadException(String.Format("  Bad signature (0x{0:X8}) looking for ZIP64 EoCD Record at position 0x{1:X8}", datum, s.Position));

            s.Read(block, 0, 8);
            Int64 Size = BitConverter.ToInt64(block, 0);

            block = new byte[Size];
            s.Read(block, 0, block.Length);

            offset64 = BitConverter.ToInt64(block, 36);
            // change for workitem 8098
            s.Seek(offset64, SeekOrigin.Begin);
            //zf.SeekFromOrigin(Offset64);
        }
Esempio n. 7
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        private static void ReadIntoInstance(ZipFile zf)
        {
            Stream s = zf.ReadStream;
            try
            {
                zf._readName = zf._name; // workitem 13915
                if (!s.CanSeek)
                {
                    ReadIntoInstance_Orig(zf);
                    return;
                }

                zf.OnReadStarted();

                // change for workitem 8098
                //zf._originPosition = s.Position;

                // Try reading the central directory, rather than scanning the file.

                uint datum = ReadFirstFourBytes(s);

                if (datum == ZipConstants.EndOfCentralDirectorySignature)
                    return;


                // start at the end of the file...
                // seek backwards a bit, then look for the EoCD signature.
                int nTries = 0;
                bool success = false;

                // The size of the end-of-central-directory-footer plus 2 bytes is 18.
                // This implies an archive comment length of 0.  We'll add a margin of
                // safety and start "in front" of that, when looking for the
                // EndOfCentralDirectorySignature
                long posn = s.Length - 64;
                long maxSeekback = Math.Max(s.Length - 0x4000, 10);
                do
                {
                    if (posn < 0) posn = 0;  // BOF
                    s.Seek(posn, SeekOrigin.Begin);
                    long bytesRead = SharedUtilities.FindSignature(s, (int)ZipConstants.EndOfCentralDirectorySignature);
                    if (bytesRead != -1)
                        success = true;
                    else
                    {
                        if (posn==0) break; // started at the BOF and found nothing
                        nTries++;
                        // Weird: with NETCF, negative offsets from SeekOrigin.End DO
                        // NOT WORK. So rather than seek a negative offset, we seek
                        // from SeekOrigin.Begin using a smaller number.
                        posn -= (32 * (nTries + 1) * nTries);
                    }
                }
                while (!success && posn > maxSeekback);

                if (success)
                {
                    // workitem 8299
                    zf._locEndOfCDS = s.Position - 4;

                    byte[] block = new byte[16];
                    s.Read(block, 0, block.Length);

                    zf._diskNumberWithCd = BitConverter.ToUInt16(block, 2);

                    if (zf._diskNumberWithCd == 0xFFFF)
                        throw new ZipException("Spanned archives with more than 65534 segments are not supported at this time.");

                    zf._diskNumberWithCd++; // I think the number in the file differs from reality by 1

                    int i = 12;

                    uint offset32 = (uint) BitConverter.ToUInt32(block, i);
                    if (offset32 == 0xFFFFFFFF)
                    {
                        Zip64SeekToCentralDirectory(zf);
                    }
                    else
                    {
                        zf._OffsetOfCentralDirectory = offset32;
                        // change for workitem 8098
                        s.Seek(offset32, SeekOrigin.Begin);
                    }

                    ReadCentralDirectory(zf);
                }
                else
                {
                    // Could not find the central directory.
                    // Fallback to the old method.
                    // workitem 8098: ok
                    //s.Seek(zf._originPosition, SeekOrigin.Begin);
                    s.Seek(0L, SeekOrigin.Begin);
                    ReadIntoInstance_Orig(zf);
                }
            }
            catch (Exception ex1)
            {
                if (zf._ReadStreamIsOurs && zf._readstream != null)
                {
                    try
                    {
#if NETCF
                        zf._readstream.Close();
#else
                        zf._readstream.Dispose();
#endif
                        zf._readstream = null;
                    }
                    finally { }
                }

                throw new ZipException("Cannot read that as a ZipFile", ex1);
            }

            // the instance has been read in
            zf._contentsChanged = false;
        }
Esempio n. 8
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        /// <summary>
        /// Reads a zip archive from a stream, using the specified text Encoding, the
        /// specified TextWriter for status messages,
        /// and the specified ReadProgress event handler.
        /// </summary>
        ///
        /// <remarks>
        /// <para>
        /// Reading of zip content begins at the current position in the stream.  This
        /// means if you have a stream that concatenates regular data and zip data, if
        /// you position the open, readable stream at the start of the zip data, you
        /// will be able to read the zip archive using this constructor, or any of the
        /// ZipFile constructors that accept a <see cref="System.IO.Stream" /> as
        /// input. Some examples of where this might be useful: the zip content is
        /// concatenated at the end of a regular EXE file, as some self-extracting
        /// archives do.  (Note: SFX files produced by DotNetZip do not work this
        /// way). Another example might be a stream being read from a database, where
        /// the zip content is embedded within an aggregate stream of data.
        /// </para>
        /// </remarks>
        ///
        /// <param name="zipStream">the stream containing the zip data.</param>
        ///
        /// <param name="statusMessageWriter">
        /// The <c>System.IO.TextWriter</c> to which verbose status messages are written
        /// during operations on the <c>ZipFile</c>.  For example, in a console
        /// application, System.Console.Out works, and will get a message for each entry
        /// added to the ZipFile.  If the TextWriter is <c>null</c>, no verbose messages
        /// are written.
        /// </param>
        ///
        /// <param name="encoding">
        /// The text encoding to use when reading entries that do not have the UTF-8
        /// encoding bit set.  Be careful specifying the encoding.  If the value you use
        /// here is not the same as the Encoding used when the zip archive was created
        /// (possibly by a different archiver) you will get unexpected results and
        /// possibly exceptions.  See the <see cref="ProvisionalAlternateEncoding"/>
        /// property for more information.
        /// </param>
        ///
        /// <param name="readProgress">
        /// An event handler for Read operations.
        /// </param>
        ///
        /// <returns>an instance of ZipFile</returns>
        private static ZipFile Read(Stream zipStream,
                                   TextWriter statusMessageWriter,
                                   System.Text.Encoding encoding,
                                   EventHandler<ReadProgressEventArgs> readProgress)
        {
            if (zipStream == null)
                throw new ArgumentNullException("zipStream");

            ZipFile zf = new ZipFile();
            zf._StatusMessageTextWriter = statusMessageWriter;
            zf._alternateEncoding = encoding ?? ZipFile.DefaultEncoding;
            zf._alternateEncodingUsage = ZipOption.Always;
            if (readProgress != null)
                zf.ReadProgress += readProgress;
            zf._readstream = (zipStream.Position == 0L)
                ? zipStream
                : new OffsetStream(zipStream);
            zf._ReadStreamIsOurs = false;
            if (zf.Verbose) zf._StatusMessageTextWriter.WriteLine("reading from stream...");

            ReadIntoInstance(zf);
            return zf;
        }
Esempio n. 9
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        /// <summary>
        /// Reads a zip file archive using the specified text encoding,  the specified
        /// TextWriter for status messages, and the specified ReadProgress event handler,
        /// and returns the instance.
        /// </summary>
        ///
        /// <param name="fileName">
        /// The name of the zip archive to open.
        /// This can be a fully-qualified or relative pathname.
        /// </param>
        ///
        /// <param name="readProgress">
        /// An event handler for Read operations.
        /// </param>
        ///
        /// <param name="statusMessageWriter">
        /// The <c>System.IO.TextWriter</c> to use for writing verbose status messages
        /// during operations on the zip archive.  A console application may wish to
        /// pass <c>System.Console.Out</c> to get messages on the Console. A graphical
        /// or headless application may wish to capture the messages in a different
        /// <c>TextWriter</c>, such as a <c>System.IO.StringWriter</c>.
        /// </param>
        ///
        /// <param name="encoding">
        /// The <c>System.Text.Encoding</c> to use when reading in the zip archive. Be
        /// careful specifying the encoding.  If the value you use here is not the same
        /// as the Encoding used when the zip archive was created (possibly by a
        /// different archiver) you will get unexpected results and possibly exceptions.
        /// </param>
        ///
        /// <returns>The instance read from the zip archive.</returns>
        ///
        private static ZipFile Read(string fileName,
                                   TextWriter statusMessageWriter,
                                   System.Text.Encoding encoding,
                                   EventHandler<ReadProgressEventArgs> readProgress)
        {
            ZipFile zf = new ZipFile();
            zf.AlternateEncoding = encoding ?? DefaultEncoding;
            zf.AlternateEncodingUsage = ZipOption.Always;
            zf._StatusMessageTextWriter = statusMessageWriter;
            zf._name = fileName;
            if (readProgress != null)
                zf.ReadProgress = readProgress;

            if (zf.Verbose) zf._StatusMessageTextWriter.WriteLine("reading from {0}...", fileName);

            ReadIntoInstance(zf);
            zf._fileAlreadyExists = true;

            return zf;
        }
Esempio n. 10
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 public ZipContainer(Object o)
 {
     _zf = (o as ZipFile);
     _zos = (o as ZipOutputStream);
     _zis = (o as ZipInputStream);
 }
Esempio n. 11
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 /// <summary>
 ///   Rewrite the directory within a zipfile.
 /// </summary>
 ///
 /// <remarks>
 ///
 /// <para>
 ///   In cases of data error, the directory in a zip file can get out of
 ///   synch with the entries in the zip file.  This method attempts to fix
 ///   the zip file if this has occurred.
 /// </para>
 ///
 /// <para> This can take a long time for large zip files. </para>
 ///
 /// <para> This won't work if the zip file uses a non-standard
 /// code page - neither IBM437 nor UTF-8. </para>
 ///
 /// <para>
 ///   This method is not supported in the Reduced or Compact Framework
 ///   versions of DotNetZip.
 /// </para>
 ///
 /// <para>
 ///   Developers using COM can use the <see
 ///   cref="ComHelper.FixZipDirectory(String)">ComHelper.FixZipDirectory(String)</see>
 ///   method.
 /// </para>
 ///
 /// </remarks>
 ///
 /// <param name="zipFileName">The filename to of the zip file to fix.</param>
 ///
 /// <seealso cref="CheckZip(string)"/>
 /// <seealso cref="CheckZip(string,bool,System.IO.TextWriter)"/>
 public static void FixZipDirectory(string zipFileName)
 {
     using (var zip = new ZipFile())
     {
         zip.FullScan = true;
         zip.Initialize(zipFileName);
         zip.Save(zipFileName);
     }
 }
Esempio n. 12
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        /// <summary>
        ///   Checks a zip file to see if its directory is consistent,
        ///   and optionally fixes the directory if necessary.
        /// </summary>
        ///
        /// <remarks>
        ///
        /// <para>
        ///   In cases of data error, the directory within a zip file can get out of
        ///   synch with the entries in the zip file.  This method checks the given
        ///   zip file, and returns true if this has occurred. It also optionally
        ///   fixes the zipfile, saving the fixed copy in <em>Name</em>_Fixed.zip.
        /// </para>
        ///
        /// <para>
        ///   This method may take a long time to run for large zip files.  It
        ///   will take even longer if the file actually needs to be fixed, and if
        ///   <c>fixIfNecessary</c> is true.
        /// </para>
        ///
        /// <para>
        ///   This method is not supported in the Reduced or Compact
        ///   Framework versions of DotNetZip.
        /// </para>
        ///
        /// </remarks>
        ///
        /// <param name="zipFileName">The filename to of the zip file to check.</param>
        ///
        /// <param name="fixIfNecessary">If true, the method will fix the zip file if
        ///     necessary.</param>
        ///
        /// <param name="writer">
        /// a TextWriter in which messages generated while checking will be written.
        /// </param>
        ///
        /// <returns>true if the named zip is OK; false if the file needs to be fixed.</returns>
        ///
        /// <seealso cref="CheckZip(string)"/>
        /// <seealso cref="FixZipDirectory(string)"/>
        public static bool CheckZip(string zipFileName, bool fixIfNecessary,
                                    TextWriter writer)

        {
            ZipFile zip1 = null, zip2 = null;
            bool isOk = true;
            try
            {
                zip1 = new ZipFile();
                zip1.FullScan = true;
                zip1.Initialize(zipFileName);

                zip2 = ZipFile.Read(zipFileName);

                foreach (var e1 in zip1)
                {
                    foreach (var e2 in zip2)
                    {
                        if (e1.FileName == e2.FileName)
                        {
                            if (e1._RelativeOffsetOfLocalHeader != e2._RelativeOffsetOfLocalHeader)
                            {
                                isOk = false;
                                if (writer != null)
                                writer.WriteLine("{0}: mismatch in RelativeOffsetOfLocalHeader  (0x{1:X16} != 0x{2:X16})",
                                                        e1.FileName, e1._RelativeOffsetOfLocalHeader,
                                                        e2._RelativeOffsetOfLocalHeader);
                            }
                            if (e1._CompressedSize != e2._CompressedSize)
                            {
                                isOk = false;
                                if (writer != null)
                                writer.WriteLine("{0}: mismatch in CompressedSize  (0x{1:X16} != 0x{2:X16})",
                                                        e1.FileName, e1._CompressedSize,
                                                        e2._CompressedSize);
                            }
                            if (e1._UncompressedSize != e2._UncompressedSize)
                            {
                                isOk = false;
                                if (writer != null)
                                writer.WriteLine("{0}: mismatch in UncompressedSize  (0x{1:X16} != 0x{2:X16})",
                                                        e1.FileName, e1._UncompressedSize,
                                                        e2._UncompressedSize);
                            }
                            if (e1.CompressionMethod != e2.CompressionMethod)
                            {
                                isOk = false;
                                if (writer != null)
                                writer.WriteLine("{0}: mismatch in CompressionMethod  (0x{1:X4} != 0x{2:X4})",
                                                        e1.FileName, e1.CompressionMethod,
                                                        e2.CompressionMethod);
                            }
                            if (e1.Crc != e2.Crc)
                            {
                                isOk = false;
                                if (writer != null)
                                writer.WriteLine("{0}: mismatch in Crc32  (0x{1:X4} != 0x{2:X4})",
                                                        e1.FileName, e1.Crc,
                                                        e2.Crc);
                            }

                            // found a match, so stop the inside loop
                            break;
                        }
                    }
                }

                zip2.Dispose();
                zip2 = null;

                if (!isOk && fixIfNecessary)
                {
                    string newFileName = Path.GetFileNameWithoutExtension(zipFileName);
                    newFileName = System.String.Format("{0}_fixed.zip", newFileName);
                    zip1.Save(newFileName);
                }
            }
            finally
            {
                if (zip1 != null) zip1.Dispose();
                if (zip2 != null) zip2.Dispose();
            }
            return isOk;
        }
Esempio n. 13
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        /// <summary>
        ///   Reads one entry from the zip directory structure in the zip file.
        /// </summary>
        ///
        /// <param name="zf">
        ///   The zipfile for which a directory entry will be read.  From this param, the
        ///   method gets the ReadStream and the expected text encoding
        ///   (ProvisionalAlternateEncoding) which is used if the entry is not marked
        ///   UTF-8.
        /// </param>
        ///
        /// <param name="previouslySeen">
        ///   a list of previously seen entry names; used to prevent duplicates.
        /// </param>
        ///
        /// <returns>the entry read from the archive.</returns>
        internal static ZipEntry ReadDirEntry(ZipFile zf,
                                              Dictionary<String,Object> previouslySeen)
        {
            System.IO.Stream s = zf.ReadStream;
            System.Text.Encoding expectedEncoding = (zf.AlternateEncodingUsage == ZipOption.Always)
                ? zf.AlternateEncoding
                : ZipFile.DefaultEncoding;

            int signature = Zephyr.Utils.Ionic.Zip.SharedUtilities.ReadSignature(s);
            // return null if this is not a local file header signature
            if (IsNotValidZipDirEntrySig(signature))
            {
                s.Seek(-4, System.IO.SeekOrigin.Current);
                // workitem 10178
                Zephyr.Utils.Ionic.Zip.SharedUtilities.Workaround_Ladybug318918(s);

                // Getting "not a ZipDirEntry signature" here is not always wrong or an
                // error.  This can happen when walking through a zipfile.  After the
                // last ZipDirEntry, we expect to read an
                // EndOfCentralDirectorySignature.  When we get this is how we know
                // we've reached the end of the central directory.
                if (signature != ZipConstants.EndOfCentralDirectorySignature &&
                    signature != ZipConstants.Zip64EndOfCentralDirectoryRecordSignature &&
                    signature != ZipConstants.ZipEntrySignature  // workitem 8299
                    )
                {
                    throw new BadReadException(String.Format("  Bad signature (0x{0:X8}) at position 0x{1:X8}", signature, s.Position));
                }
                return null;
            }

            int bytesRead = 42 + 4;
            byte[] block = new byte[42];
            int n = s.Read(block, 0, block.Length);
            if (n != block.Length) return null;

            int i = 0;
            ZipEntry zde = new ZipEntry();
            zde.AlternateEncoding = expectedEncoding;
            zde._Source = ZipEntrySource.ZipFile;
            zde._container = new ZipContainer(zf);

            unchecked
            {
                zde._VersionMadeBy = (short)(block[i++] + block[i++] * 256);
                zde._VersionNeeded = (short)(block[i++] + block[i++] * 256);
                zde._BitField = (short)(block[i++] + block[i++] * 256);
                zde._CompressionMethod = (Int16)(block[i++] + block[i++] * 256);
                zde._TimeBlob = block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256;
                zde._LastModified = Zephyr.Utils.Ionic.Zip.SharedUtilities.PackedToDateTime(zde._TimeBlob);
                zde._timestamp |= ZipEntryTimestamp.DOS;

                zde._Crc32 = block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256;
                zde._CompressedSize = (uint)(block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256);
                zde._UncompressedSize = (uint)(block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256);
            }

            // preserve
            zde._CompressionMethod_FromZipFile = zde._CompressionMethod;

            zde._filenameLength = (short)(block[i++] + block[i++] * 256);
            zde._extraFieldLength = (short)(block[i++] + block[i++] * 256);
            zde._commentLength = (short)(block[i++] + block[i++] * 256);
            zde._diskNumber = (UInt32)(block[i++] + block[i++] * 256);

            zde._InternalFileAttrs = (short)(block[i++] + block[i++] * 256);
            zde._ExternalFileAttrs = block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256;

            zde._RelativeOffsetOfLocalHeader = (uint)(block[i++] + block[i++] * 256 + block[i++] * 256 * 256 + block[i++] * 256 * 256 * 256);

            // workitem 7801
            zde.IsText = ((zde._InternalFileAttrs & 0x01) == 0x01);

            block = new byte[zde._filenameLength];
            n = s.Read(block, 0, block.Length);
            bytesRead += n;
            if ((zde._BitField & 0x0800) == 0x0800)
            {
                // UTF-8 is in use
                zde._FileNameInArchive = Zephyr.Utils.Ionic.Zip.SharedUtilities.Utf8StringFromBuffer(block);
            }
            else
            {
                zde._FileNameInArchive = Zephyr.Utils.Ionic.Zip.SharedUtilities.StringFromBuffer(block, expectedEncoding);
            }

            // workitem 10330
            // insure unique entry names
            while (previouslySeen.ContainsKey(zde._FileNameInArchive))
            {
                zde._FileNameInArchive = CopyHelper.AppendCopyToFileName(zde._FileNameInArchive);
                zde._metadataChanged = true;
            }

            if (zde.AttributesIndicateDirectory)
                zde.MarkAsDirectory();  // may append a slash to filename if nec.
            // workitem 6898
            else if (zde._FileNameInArchive.EndsWith("/")) zde.MarkAsDirectory();

            zde._CompressedFileDataSize = zde._CompressedSize;
            if ((zde._BitField & 0x01) == 0x01)
            {
                // this may change after processing the Extra field
                zde._Encryption_FromZipFile = zde._Encryption =
                    EncryptionAlgorithm.PkzipWeak;
                zde._sourceIsEncrypted = true;
            }

            if (zde._extraFieldLength > 0)
            {
                zde._InputUsesZip64 = (zde._CompressedSize == 0xFFFFFFFF ||
                      zde._UncompressedSize == 0xFFFFFFFF ||
                      zde._RelativeOffsetOfLocalHeader == 0xFFFFFFFF);

                // Console.WriteLine("  Input uses Z64?:      {0}", zde._InputUsesZip64);

                bytesRead += zde.ProcessExtraField(s, zde._extraFieldLength);
                zde._CompressedFileDataSize = zde._CompressedSize;
            }

            // we've processed the extra field, so we know the encryption method is set now.
            if (zde._Encryption == EncryptionAlgorithm.PkzipWeak)
            {
                // the "encryption header" of 12 bytes precedes the file data
                zde._CompressedFileDataSize -= 12;
            }
#if AESCRYPTO
            else if (zde.Encryption == EncryptionAlgorithm.WinZipAes128 ||
                        zde.Encryption == EncryptionAlgorithm.WinZipAes256)
            {
                zde._CompressedFileDataSize = zde.CompressedSize -
                    (ZipEntry.GetLengthOfCryptoHeaderBytes(zde.Encryption) + 10);
                zde._LengthOfTrailer = 10;
            }
#endif

            // tally the trailing descriptor
            if ((zde._BitField & 0x0008) == 0x0008)
            {
                // sig, CRC, Comp and Uncomp sizes
                if (zde._InputUsesZip64)
                    zde._LengthOfTrailer += 24;
                else
                    zde._LengthOfTrailer += 16;
            }

            // workitem 12744
            zde.AlternateEncoding = ((zde._BitField & 0x0800) == 0x0800)
                ? System.Text.Encoding.UTF8
                :expectedEncoding;

            zde.AlternateEncodingUsage = ZipOption.Always;

            if (zde._commentLength > 0)
            {
                block = new byte[zde._commentLength];
                n = s.Read(block, 0, block.Length);
                bytesRead += n;
                if ((zde._BitField & 0x0800) == 0x0800)
                {
                    // UTF-8 is in use
                    zde._Comment = Zephyr.Utils.Ionic.Zip.SharedUtilities.Utf8StringFromBuffer(block);
                }
                else
                {
                    zde._Comment = Zephyr.Utils.Ionic.Zip.SharedUtilities.StringFromBuffer(block, expectedEncoding);
                }
            }
            //zde._LengthOfDirEntry = bytesRead;
            return zde;
        }