Question

I am currently working with SharpZipLib under .NET 2.0 and via this I need to compress a single file to a single compressed archive. In order to do this I am currently using the following:

string tempFilePath = @"C:\Users\Username\AppData\Local\Temp\tmp9AE0.tmp.xml";
string archiveFilePath = @"C:\Archive\Archive_[UTC TIMESTAMP].zip";

FileInfo inFileInfo = new FileInfo(tempFilePath);
ICSharpCode.SharpZipLib.Zip.FastZip fZip = new ICSharpCode.SharpZipLib.Zip.FastZip();
fZip.CreateZip(archiveFilePath, inFileInfo.Directory.FullName, false, inFileInfo.Name);

This works exactly (ish) as it should, however while testing I have encountered a minor gotcha. Lets say that my temp directory (i.e. the directory that contains the uncompressed input file) contains the following files:

tmp9AE0.tmp.xml //The input file I want to compress
xxx_tmp9AE0.tmp.xml // Some other file
yyy_tmp9AE0.tmp.xml // Some other file
wibble.dat // Some other file

When I run the compression all the .xml files are included in the compressed archive. The reason for this is because of the final fileFilter parameter passed to the CreateZip method. Under the hood SharpZipLib is performing a pattern match and this also picks up the files prefixed with xxx_ and yyy_. I assume it would also pick up anything postfixed as well.

So the question is, how can I compress a single file with SharpZipLib? Then again maybe the question is how can I format that fileFilter so that the match can only ever pick up the file I want to compress and nothing else.

As an aside, is there any reason as to why System.IO.Compression not include a ZipStream class? (It only supports GZipStream)

EDIT : Solution (Derived from accepted answer from Hans Passant)

This is the compression method I implemented:

private static void CompressFile(string inputPath, string outputPath)
{
    FileInfo outFileInfo = new FileInfo(outputPath);
    FileInfo inFileInfo = new FileInfo(inputPath);

    // Create the output directory if it does not exist
    if (!Directory.Exists(outFileInfo.Directory.FullName))
    {
        Directory.CreateDirectory(outFileInfo.Directory.FullName);
    }

    // Compress
    using (FileStream fsOut = File.Create(outputPath))
    {
        using (ICSharpCode.SharpZipLib.Zip.ZipOutputStream zipStream = new ICSharpCode.SharpZipLib.Zip.ZipOutputStream(fsOut))
        {
            zipStream.SetLevel(3);

            ICSharpCode.SharpZipLib.Zip.ZipEntry newEntry = new ICSharpCode.SharpZipLib.Zip.ZipEntry(inFileInfo.Name);
            newEntry.DateTime = DateTime.UtcNow;
            zipStream.PutNextEntry(newEntry);

            byte[] buffer = new byte[4096];
            using (FileStream streamReader = File.OpenRead(inputPath))
            {
                ICSharpCode.SharpZipLib.Core.StreamUtils.Copy(streamReader, zipStream, buffer);
            }

            zipStream.CloseEntry();
            zipStream.IsStreamOwner = true;
            zipStream.Close();
        }
    }
}

Answer 1

This is an XY problem, just don’t use FastZip. Follow the first example on this web page to avoid accidents.