How can I unzip a file to a .NET memory stream?

Question

I have files (from 3rd parties) that are being FTP'd to a directory on our server. I download them and process them even 'x' minutes. Works great.

Now, some of the files are .zip files. Which means I can't process them. I need to unzip them first.

FTP has no concept of zip/unzipping - so I'll need to grab the zip file, unzip it, then process it.

Looking at the MSDN zip api, there seems to be no way i can unzip to a memory stream?

So is the only way to do this...

1. Unzip to a file (what directory? need some -very- temp location ...)
2. Read the file contents
3. Delete file.

NOTE: The contents of the file are small - say 4k <-> 1000k.

Answer 1

Zip compression support is built in:

using System.IO; using System.IO.Compression; // ^^^ requires a reference to System.IO.Compression.dll static class Program {     const string path = ...     static void Main()     {         using(var file = File.OpenRead(path))         using(var zip = new ZipArchive(file, ZipArchiveMode.Read))         {             foreach(var entry in zip.Entries)             {                 using(var stream = entry.Open())                 {                     // do whatever we want with stream                     // ...                 }             }         }     } } 

Normally you should avoid copying it into another stream - just use it "as is", however, if you absolutely need it in a MemoryStream, you could do:

using(var ms = new MemoryStream()) {     stream.CopyTo(ms);     ms.Position = 0; // rewind     // do something with ms } 

Answer 2

You can use ZipArchiveEntry.Open to get a stream.

This code assumes the zip archive has one text file.

using (FileStream fs = new FileStream(path, FileMode.Open)) using (ZipArchive zip = new ZipArchive(fs) ) {     var entry = zip.Entries.First();      using (StreamReader sr = new StreamReader(entry.Open()))     {         Console.WriteLine(sr.ReadToEnd());     } }