小字节[]块导致图像损坏

我正试图将文件复制到小块大小的web处理程序。当缓冲区相对较大并且总是与图像大小相同时，它工作得很好。但是我得到的图像失真块尺寸太小。

为什么当我把相同的字节重新组合在一起时它会改变?

OpenFileDialog o = new OpenFileDialog();
o.ShowDialog();
using (WebClient webClient = new WebClient())
{
    int index = 0;
    var tmpName = Guid.NewGuid().ToString();
    const int chunkSize = 10*1024;
    webClient.Headers.Add("Filename", "");
    using (var file = o.OpenFile())
    {
        int bytesRead;
        //Using ChunkSize will give image distortion. But file.length works. So does dividing by 10 to result in 10 chunks. Why?
        byte[] buffer = new byte[file.Length/10];
        int position = 0;
        while (position < file.Length)
        {
            if (position + buffer.Length > file.Length)
            {
                buffer = new byte[file.Length - position];
            }
            bytesRead = file.Read(buffer, 0, buffer.Length);
            position += bytesRead;
            var fileName = string.Format("{0}.{1}.{2}", tmpName, index, o.SafeFileName);
            webClient.Headers["Filename"] = fileName;
            //webClient.Headers["blockSize"] = buffer.Length.ToString();
            webClient.UploadData("http://localhost:49815/FileUpload.ashx", buffer);
            index++;
        }
    }
    var values = new NameValueCollection();
    values.Add("Filename", string.Format("{0}.{1}", tmpName, o.SafeFileName));
    values.Add("Complete", "true");
    webClient.Headers.Clear();
    webClient.UploadValues("http://localhost:49815/FileUpload.ashx", values);

}

我测试了什么

• 如果我不传递到块到文件上传。然后把这些块放到客户端应用程序上，它工作得很好。
• 文件大小与服务器端完全匹配

• 同样的问题发生保存破碎的文件到相同的位置。所以HTTP和它没有任何关系。

  private void CombineFiles(string filename)
  {
      var fileguid = filename.Substring(0, filename.IndexOf(".") + 1);
      var shortFileName = filename.Replace(fileguid, "");
      var files = Directory.GetFiles(AppDomain.CurrentDomain.BaseDirectory + "images", fileguid + "*");
      using (var filestream = File.Create(AppDomain.CurrentDomain.BaseDirectory + "images/" + shortFileName))
      {
          foreach (string file in files)
          {
              var fileBuffer = File.ReadAllBytes(file);
              filestream.Write(fileBuffer, 0, fileBuffer.Length);
              File.Delete(file);
          }
      }
  }
  

var directory = new DirectoryInfo(AppDomain.CurrentDomain.BaseDirectory + "images");
var files = directory.GetFiles(fileguid + "*").OrderBy(x => x.CreationTime).ToArray();