How to create a zip file in memory, starting from file bytes?

Question

I try to create a zip file in memory with c#, but the result is a zip file with corrupted files inside it. All file to zip are in a database. I store the bytes. The files are PDF. my code is the following

//[extract bytes and file name for every file]

using (var zipArchiveMemoryStream = new MemoryStream())
{
    using (var zipArchive = new ZipArchive(zipArchiveMemoryStream,
                                           ZipArchiveMode.Create, true))
    {
        foreach (var file in fileData)
        {
            var zipEntry = zipArchive.CreateEntry(file.FileName);
            using (var entryStream = zipEntry.Open())
            {
                using (var tmpMemory = new MemoryStream(file.Bytes))
                {
                    tmpMemory.CopyTo(entryStream);
                };

            }
        }
    }
    zipArchiveMemoryStream.Position = 0;
    result = zipArchiveMemoryStream.GetBuffer();

//[download zip file]

Thanks in advance for your support

SOLUTION BY TONIGNO: the problem was that i use GetBuffer(); instead ToArray();

using (var zipArchiveMemoryStream = new MemoryStream())
        {
            using (var zipArchive = new ZipArchive(zipArchiveMemoryStream, ZipArchiveMode.Create, true))
            {
                foreach (var file in fileData)
                {
                    var zipEntry = zipArchive.CreateEntry(file.FileName);
                    using (var entryStream = zipEntry.Open())
                    {
                        using (var tmpMemory = new MemoryStream(file.Bytes))
                        {
                            tmpMemory.CopyTo(entryStream);
                        };

                    }
                }
            }

            zipArchiveMemoryStream.Seek(0, SeekOrigin.Begin);
            result = zipArchiveMemoryStream.ToArray();
        }

        return result;

i cannot extract the files fron the zip. wirar say file are corrupted — Luca Dalsass, Jul 10 '15 at 09:58

score 5 · Accepted Answer · edited May 23 '17 at 12:07

Try to take a look to this: Creating a ZIP Archive in Memory Using System.IO.Compression. The solution is this:

using (var memoryStream = new MemoryStream())
{
   using (var archive = new ZipArchive(memoryStream, ZipArchiveMode.Create, true))
   {
      var demoFile = archive.CreateEntry("foo.txt");

      using (var entryStream = demoFile.Open())
      using (var streamWriter = new StreamWriter(entryStream))
      {
         streamWriter.Write("Bar!");
      }
   }

   using (var fileStream = new FileStream(@"C:\Temp\test.zip", FileMode.Create))
   {
      memoryStream.Seek(0, SeekOrigin.Begin);
      memoryStream.CopyTo(fileStream);
   }
}

It explains how to create the zip archive in memory and contains a link to another useful article that explains the use of the leaveOpen argument to prevent the closing of the stream: ZipArchive creates invalid ZIP file that contains this solution:

using (MemoryStream zipStream = new MemoryStream())
{
    using (ZipArchive zip = new ZipArchive(zipStream, ZipArchiveMode.Create, true))
    {
        var entry = zip.CreateEntry("test.txt");
        using (StreamWriter sw = new StreamWriter(entry.Open()))
        {
            sw.WriteLine(
            "Etiam eros nunc, hendrerit nec malesuada vitae, pretium at ligula.");
        }
    }

    var file = await Windows.Storage.ApplicationData.Current.LocalFolder.CreateFileAsync(
    "test.zip",
    CreationCollisionOption.ReplaceExisting);

    zipStream.Position = 0;
    using (Stream s = await file.OpenStreamForWriteAsync())
    {
        zipStream.CopyTo(s);
    }
}

I hope it's helpful!

EDIT

Instead of zipArchiveMemoryStream.GetBuffer() use zipArchiveMemoryStream.ToArray()

While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference. Link-only answers can become invalid if the linked page changes. — Gerald Versluis, Jul 10 '15 at 09:01
i take another try but i have already read the linked articles. The difference in my case is that i do not have physical files but only the bytes. I can't save it on hard drive before to zip it. I'll let you know — Luca Dalsass, Jul 10 '15 at 09:52
Ok, instead of `zipArchiveMemoryStream.GetBuffer()` try to use `zipArchiveMemoryStream.ToArray()` — Tonigno, Jul 10 '15 at 10:28

score 0 · Answer 2 · edited Mar 03 '22 at 15:59

0

For me it worked like this:

using (var memoryStream = new MemoryStream())
{
   using (var archive = new ZipArchive(memoryStream, ZipArchiveMode.Create, true))
   {
      var file = archive.CreateEntry("file.json");
      using var entryStream = file.Open();
      using var streamWriter = new StreamWriter(entryStream);
      streamWriter.WriteLine(someJsonLine);
   }
}

edited Mar 03 '22 at 15:59

Dharman

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answered Mar 03 '22 at 15:54

Dina Bogdan

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How to create a zip file in memory, starting from file bytes?

2 Answers2

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