MimeWriter.cs

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using System.Collections.Specialized;
using System.IO;
using System.Text;
 
namespace System.Net.Mime;
 
internal sealed class MimeWriter : BaseWriter
{
    private static readonly byte[] s_DASHDASH = new byte[2] { 45, 45 };
 
    private readonly byte[] _boundaryBytes;
 
    private bool _writeBoundary = true;
 
    internal MimeWriter(Stream stream, string boundary)
        : base(stream, shouldEncodeLeadingDots: false)
    {
        if (boundary == null)
        {
            throw new ArgumentNullException("boundary");
        }
        _boundaryBytes = Encoding.ASCII.GetBytes(boundary);
    }
 
    internal override void WriteHeaders(NameValueCollection headers, bool allowUnicode)
    {
        if (headers == null)
        {
            throw new ArgumentNullException("headers");
        }
        foreach (string header in headers)
        {
            WriteHeader(header, headers[header], allowUnicode);
        }
    }
 
    internal IAsyncResult BeginClose(AsyncCallback callback, object state)
    {
        MultiAsyncResult multiAsyncResult = new MultiAsyncResult(this, callback, state);
        Close(multiAsyncResult);
        multiAsyncResult.CompleteSequence();
        return multiAsyncResult;
    }
 
    internal void EndClose(IAsyncResult result)
    {
        MultiAsyncResult.End(result);
        _stream.Close();
    }
 
    internal override void Close()
    {
        Close(null);
        _stream.Close();
    }
 
    private void Close(MultiAsyncResult multiResult)
    {
        _bufferBuilder.Append(BaseWriter.s_crlf);
        _bufferBuilder.Append(s_DASHDASH);
        _bufferBuilder.Append(_boundaryBytes);
        _bufferBuilder.Append(s_DASHDASH);
        _bufferBuilder.Append(BaseWriter.s_crlf);
        Flush(multiResult);
    }
 
    protected override void OnClose(object sender, EventArgs args)
    {
        if (_contentStream == sender)
        {
            _contentStream.Flush();
            _contentStream = null;
            _writeBoundary = true;
            _isInContent = false;
        }
    }
 
    protected override void CheckBoundary()
    {
        if (_writeBoundary)
        {
            _bufferBuilder.Append(BaseWriter.s_crlf);
            _bufferBuilder.Append(s_DASHDASH);
            _bufferBuilder.Append(_boundaryBytes);
            _bufferBuilder.Append(BaseWriter.s_crlf);
            _writeBoundary = false;
        }
    }
}