Merge pull request #900 from Blewzman/FixAggregateExceptionGetBaseException
[mono.git] / mcs / class / corlib / System.IO / StreamReader.cs
index 9102031f2f3ef4bfd276129172d6180c0f990282..8a0a9e9bb10110da7b4903c2bed329c02679494c 100644 (file)
@@ -1,16 +1,14 @@
 //
 // System.IO.StreamReader.cs
 //
-// Author:
+// Authors:
 //   Dietmar Maurer (dietmar@ximian.com)
 //   Miguel de Icaza (miguel@ximian.com) 
+//   Marek Safar (marek.safar@gmail.com)
 //
 // (C) Ximian, Inc.  http://www.ximian.com
 // Copyright (C) 2004 Novell (http://www.novell.com)
-//
-
-//
-// Copyright (C) 2004 Novell, Inc (http://www.novell.com)
+// Copyright 2011, 2013 Xamarin Inc.
 //
 // Permission is hereby granted, free of charge, to any person obtaining
 // a copy of this software and associated documentation files (the
 using System;
 using System.Text;
 using System.Runtime.InteropServices;
+#if NET_4_5
+using System.Threading.Tasks;
+#endif
 
 namespace System.IO {
        [Serializable]
-       public class StreamReader : TextReader {
+       [ComVisible (true)]
+       public class StreamReader : TextReader
+       {
+               sealed class NullStreamReader : StreamReader
+               {
+                       internal NullStreamReader ()
+                       {
+                               base_stream = Stream.Null;
+                       }
+
+                       public override int Peek ()
+                       {
+                               return -1;
+                       }
+
+                       public override int Read ()
+                       {
+                               return -1;
+                       }
+
+                       public override int Read ([In, Out] char[] buffer, int index, int count)
+                       {
+                               return 0;
+                       }
+
+                       public override string ReadLine ()
+                       {
+                               return null;
+                       }
+
+                       public override string ReadToEnd ()
+                       {
+                               return String.Empty;
+                       }
+
+                       public override Stream BaseStream {
+                               get { return Stream.Null; }
+                       }
+
+                       public override Encoding CurrentEncoding {
+                               get { return Encoding.Unicode; }
+                       }
+               }
 
                const int DefaultBufferSize = 1024;
                const int DefaultFileBufferSize = 4096;
@@ -48,11 +91,21 @@ namespace System.IO {
                // The input buffer
                //
                byte [] input_buffer;
+               
+               // Input buffer ready for recycling
+               static byte [] input_buffer_recycle;
+               static object input_buffer_recycle_lock = new object ();
 
                //
                // The decoded buffer from the above input buffer
                //
                char [] decoded_buffer;
+               static char[] decoded_buffer_recycle;
+
+               Encoding encoding;
+               Decoder decoder;
+               StringBuilder line_builder;
+               Stream base_stream;
 
                //
                // Decoded bytes in decoded_buffer.
@@ -71,84 +124,61 @@ namespace System.IO {
 
                int do_checks;
                
-               Encoding encoding;
-               Decoder decoder;
-
-               Stream base_stream;
                bool mayBlock;
-               StringBuilder line_builder;
-
-               private class NullStreamReader : StreamReader {
-                       public override int Peek ()
-                       {
-                               return -1;
-                       }
-
-                       public override int Read ()
-                       {
-                               return -1;
-                       }
-
-                       public override int Read ([In, Out] char[] buffer, int index, int count)
-                       {
-                               return 0;
-                       }
-
-                       public override string ReadLine ()
-                       {
-                               return null;
-                       }
-
-                       public override string ReadToEnd ()
-                       {
-                               return String.Empty;
-                       }
 
-                       public override Stream BaseStream
-                       {
-                               get { return Stream.Null; }
-                       }
-
-                       public override Encoding CurrentEncoding
-                       {
-                               get { return Encoding.Unicode; }
-                       }
-               }
+#if NET_4_5
+               IDecoupledTask async_task;
+               readonly bool leave_open;
+#endif
 
-               public new static readonly StreamReader Null =  (StreamReader)(new NullStreamReader());
+               public new static readonly StreamReader Null =  new NullStreamReader ();
                
-               internal StreamReader() {}
+               private StreamReader() {}
 
                public StreamReader(Stream stream)
-                       : this (stream, Encoding.UTF8Unmarked, true, DefaultBufferSize) { }
+                       : this (stream, Encoding.UTF8, true, DefaultBufferSize) { }
 
-               public StreamReader(Stream stream, bool detect_encoding_from_bytemarks)
-                       : this (stream, Encoding.UTF8Unmarked, detect_encoding_from_bytemarks, DefaultBufferSize) { }
+               public StreamReader(Stream stream, bool detectEncodingFromByteOrderMarks)
+                       : this (stream, Encoding.UTF8, detectEncodingFromByteOrderMarks, DefaultBufferSize) { }
 
                public StreamReader(Stream stream, Encoding encoding)
                        : this (stream, encoding, true, DefaultBufferSize) { }
 
-               public StreamReader(Stream stream, Encoding encoding, bool detect_encoding_from_bytemarks)
-                       : this (stream, encoding, detect_encoding_from_bytemarks, DefaultBufferSize) { }
-               
-               public StreamReader(Stream stream, Encoding encoding, bool detect_encoding_from_bytemarks, int buffer_size)
+               public StreamReader(Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks)
+                       : this (stream, encoding, detectEncodingFromByteOrderMarks, DefaultBufferSize) { }
+
+#if NET_4_5
+               public StreamReader(Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize)
+                       : this (stream, encoding, detectEncodingFromByteOrderMarks, bufferSize, false)
+               {
+               }
+
+               public StreamReader(Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize, bool leaveOpen)
+#else
+               const bool leave_open = false;
+
+               public StreamReader(Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize)
+#endif
                {
-                       Initialize (stream, encoding, detect_encoding_from_bytemarks, buffer_size);
+#if NET_4_5
+                       leave_open = leaveOpen;
+#endif
+                       Initialize (stream, encoding, detectEncodingFromByteOrderMarks, bufferSize);
                }
 
                public StreamReader(string path)
-                       : this (path, Encoding.UTF8Unmarked, true, DefaultFileBufferSize) { }
+                       : this (path, Encoding.UTF8, true, DefaultFileBufferSize) { }
 
-               public StreamReader(string path, bool detect_encoding_from_bytemarks)
-                       : this (path, Encoding.UTF8Unmarked, detect_encoding_from_bytemarks, DefaultFileBufferSize) { }
+               public StreamReader(string path, bool detectEncodingFromByteOrderMarks)
+                       : this (path, Encoding.UTF8, detectEncodingFromByteOrderMarks, DefaultFileBufferSize) { }
 
                public StreamReader(string path, Encoding encoding)
                        : this (path, encoding, true, DefaultFileBufferSize) { }
 
-               public StreamReader(string path, Encoding encoding, bool detect_encoding_from_bytemarks)
-                       : this (path, encoding, detect_encoding_from_bytemarks, DefaultFileBufferSize) { }
+               public StreamReader(string path, Encoding encoding, bool detectEncodingFromByteOrderMarks)
+                       : this (path, encoding, detectEncodingFromByteOrderMarks, DefaultFileBufferSize) { }
                
-               public StreamReader(string path, Encoding encoding, bool detect_encoding_from_bytemarks, int buffer_size)
+               public StreamReader(string path, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize)
                {
                        if (null == path)
                                throw new ArgumentNullException("path");
@@ -158,20 +188,14 @@ namespace System.IO {
                                throw new ArgumentException("path contains invalid characters");
                        if (null == encoding)
                                throw new ArgumentNullException ("encoding");
-                       if (buffer_size <= 0)
-                               throw new ArgumentOutOfRangeException ("buffer_size", "The minimum size of the buffer must be positive");
-
-                       string DirName = Path.GetDirectoryName(path);
-                       if (DirName != String.Empty && !Directory.Exists(DirName))
-                               throw new DirectoryNotFoundException ("Directory '" + DirName + "' not found.");
-                       if (!File.Exists(path))
-                               throw new FileNotFoundException("File not found.", path);
+                       if (bufferSize <= 0)
+                               throw new ArgumentOutOfRangeException ("bufferSize", "The minimum size of the buffer must be positive");
 
                        Stream stream = (Stream) File.OpenRead (path);
-                       Initialize (stream, encoding, detect_encoding_from_bytemarks, buffer_size);
+                       Initialize (stream, encoding, detectEncodingFromByteOrderMarks, bufferSize);
                }
 
-               internal void Initialize (Stream stream, Encoding encoding, bool detect_encoding_from_bytemarks, int buffer_size)
+               internal void Initialize (Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize)
                {
                        if (null == stream)
                                throw new ArgumentNullException ("stream");
@@ -179,48 +203,73 @@ namespace System.IO {
                                throw new ArgumentNullException ("encoding");
                        if (!stream.CanRead)
                                throw new ArgumentException ("Cannot read stream");
-                       if (buffer_size <= 0)
-                               throw new ArgumentOutOfRangeException ("buffer_size", "The minimum size of the buffer must be positive");
+                       if (bufferSize <= 0)
+                               throw new ArgumentOutOfRangeException ("bufferSize", "The minimum size of the buffer must be positive");
 
-                       if (buffer_size < MinimumBufferSize)
-                               buffer_size = MinimumBufferSize;
+                       if (bufferSize < MinimumBufferSize)
+                               bufferSize = MinimumBufferSize;
+                       
+                       // since GetChars() might add flushed character, it 
+                       // should have additional char buffer for extra 1 
+                       // (probably 1 is ok, but might be insufficient. I'm not sure)
+                       var decoded_buffer_size = encoding.GetMaxCharCount (bufferSize) + 1;
+
+                       //
+                       // Instead of allocating a new default buffer use the
+                       // last one if there is any available
+                       //
+                       if (bufferSize <= DefaultBufferSize && input_buffer_recycle != null) {
+                               lock (input_buffer_recycle_lock) {
+                                       if (input_buffer_recycle != null) {
+                                               input_buffer = input_buffer_recycle;
+                                               input_buffer_recycle = null;
+                                       }
+                                       
+                                       if (decoded_buffer_recycle != null && decoded_buffer_size <= decoded_buffer_recycle.Length) {
+                                               decoded_buffer = decoded_buffer_recycle;
+                                               decoded_buffer_recycle = null;
+                                       }
+                               }
+                       }
+                       
+                       if (input_buffer == null)
+                               input_buffer = new byte [bufferSize];
+                       else
+                               Array.Clear (input_buffer, 0, bufferSize);
+                       
+                       if (decoded_buffer == null)
+                               decoded_buffer = new char [decoded_buffer_size];
+                       else
+                               Array.Clear (decoded_buffer, 0, decoded_buffer_size);
 
-                       base_stream = stream;
-                       input_buffer = new byte [buffer_size];
-                       this.buffer_size = buffer_size;
+                       base_stream = stream;           
+                       this.buffer_size = bufferSize;
                        this.encoding = encoding;
                        decoder = encoding.GetDecoder ();
 
                        byte [] preamble = encoding.GetPreamble ();
-                       do_checks = detect_encoding_from_bytemarks ? 1 : 0;
+                       do_checks = detectEncodingFromByteOrderMarks ? 1 : 0;
                        do_checks += (preamble.Length == 0) ? 0 : 2;
                        
-                       decoded_buffer = new char [encoding.GetMaxCharCount (buffer_size)];
                        decoded_count = 0;
                        pos = 0;
                }
 
-               public virtual Stream BaseStream
-               {
+               public virtual Stream BaseStream {
                        get {
                                return base_stream;
                        }
                }
 
-               public virtual Encoding CurrentEncoding
-               {
+               public virtual Encoding CurrentEncoding {
                        get {
-                               if (encoding == null)
-                                       throw new Exception ();
                                return encoding;
                        }
                }
 
-#if NET_2_0
                public bool EndOfStream {
                        get { return Peek () < 0; }
                }
-#endif
 
                public override void Close ()
                {
@@ -229,9 +278,21 @@ namespace System.IO {
 
                protected override void Dispose (bool disposing)
                {
-                       if (disposing && base_stream != null)
+                       if (disposing && base_stream != null && !leave_open)
                                base_stream.Close ();
                        
+                       if (input_buffer != null && input_buffer.Length == DefaultBufferSize && input_buffer_recycle == null) {
+                               lock (input_buffer_recycle_lock) {
+                                       if (input_buffer_recycle == null) {
+                                               input_buffer_recycle = input_buffer;
+                                       }
+                                       
+                                       if (decoded_buffer_recycle == null) {
+                                               decoded_buffer_recycle = decoded_buffer;
+                                       }
+                               }
+                       }
+                       
                        input_buffer = null;
                        decoded_buffer = null;
                        encoding = null;
@@ -269,8 +330,8 @@ namespace System.IO {
                                        this.encoding = Encoding.BigEndianUnicode;
                                        return 2;
                                }
-
-                               if (input_buffer [0] == 0xff && input_buffer [1] == 0xfe){
+                               if (input_buffer [0] == 0xff && input_buffer [1] == 0xfe && count < 4) {
+                                       // If we don't have enough bytes we can't check for UTF32, so use Unicode
                                        this.encoding = Encoding.Unicode;
                                        return 2;
                                }
@@ -282,6 +343,31 @@ namespace System.IO {
                                        this.encoding = Encoding.UTF8Unmarked;
                                        return 3;
                                }
+
+                               if (count < 4) {
+                                       if (input_buffer [0] == 0xff && input_buffer [1] == 0xfe && input_buffer [2] != 0) {
+                                               this.encoding = Encoding.Unicode;
+                                               return 2;
+                                       }
+                                       return 0;
+                               }
+
+                               if (input_buffer [0] == 0 && input_buffer [1] == 0
+                                       && input_buffer [2] == 0xfe && input_buffer [3] == 0xff)
+                               {
+                                       this.encoding = Encoding.BigEndianUTF32;
+                                       return 4;
+                               }
+
+                               if (input_buffer [0] == 0xff && input_buffer [1] == 0xfe) {
+                                       if (input_buffer [2] == 0 && input_buffer[3] == 0) {
+                                               this.encoding = Encoding.UTF32;
+                                               return 4;
+                                       }
+
+                                       this.encoding = Encoding.Unicode;
+                                       return 2;
+                               }
                        }
 
                        return 0;
@@ -289,6 +375,8 @@ namespace System.IO {
 
                public void DiscardBufferedData ()
                {
+                       CheckState ();
+
                        pos = decoded_count = 0;
                        mayBlock = false;
                        // Discard internal state of the decoder too.
@@ -296,85 +384,109 @@ namespace System.IO {
                }
                
                // the buffer is empty, fill it again
-               private int ReadBuffer ()
+               // Keep in sync with ReadBufferAsync
+               int ReadBuffer ()
                {
                        pos = 0;
-                       int cbEncoded = 0;
 
                        // keep looping until the decoder gives us some chars
                        decoded_count = 0;
-                       int parse_start = 0;
-                       do      
-                       {
-                               cbEncoded = base_stream.Read (input_buffer, 0, buffer_size);
-                               
+                       do {
+                               var cbEncoded = base_stream.Read (input_buffer, 0, buffer_size);
                                if (cbEncoded <= 0)
                                        return 0;
 
-                               mayBlock = (cbEncoded < buffer_size);
-                               if (do_checks > 0){
-                                       Encoding old = encoding;
-                                       parse_start = DoChecks (cbEncoded);
-                                       if (old != encoding){
-                                               decoder = encoding.GetDecoder ();
-                                       }
-                                       do_checks = 0;
-                                       cbEncoded -= parse_start;
-                               }
-                               
-                               decoded_count += decoder.GetChars (input_buffer, parse_start, cbEncoded, decoded_buffer, 0);
-                               parse_start = 0;
+                               decoded_count = ReadBufferCore (cbEncoded);
                        } while (decoded_count == 0);
 
                        return decoded_count;
                }
 
+               int ReadBufferCore (int cbEncoded)
+               {
+                       int parse_start;
+
+                       mayBlock = cbEncoded < buffer_size;
+                       if (do_checks > 0){
+                               Encoding old = encoding;
+                               parse_start = DoChecks (cbEncoded);
+                               if (old != encoding){
+                                       int old_decoded_size = old.GetMaxCharCount (buffer_size) + 1;
+                                       int new_decoded_size = encoding.GetMaxCharCount (buffer_size) + 1;
+                                       if (old_decoded_size != new_decoded_size)
+                                               decoded_buffer = new char [new_decoded_size];
+                                       decoder = encoding.GetDecoder ();
+                               }
+                               do_checks = 0;
+                               cbEncoded -= parse_start;
+                       } else {
+                               parse_start = 0;
+                       }
+                               
+                       return decoder.GetChars (input_buffer, parse_start, cbEncoded, decoded_buffer, 0);
+               }
+
+               //
+               // Peek can block:
+               // http://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=96484
+               //
                public override int Peek ()
                {
-                       if (base_stream == null)
-                               throw new ObjectDisposedException ("StreamReader", "Cannot read from a closed StreamReader");
-                       if (pos >= decoded_count && (mayBlock || ReadBuffer () == 0))
+                       CheckState ();
+
+                       if (pos >= decoded_count && ReadBuffer () == 0)
                                return -1;
 
                        return decoded_buffer [pos];
                }
 
+               //
+               // Used internally by our console, as it previously depended on Peek() being a
+               // routine that would not block.
+               //
+               internal bool DataAvailable ()
+               {
+                       return pos < decoded_count;
+               }
+               
                public override int Read ()
                {
-                       if (base_stream == null)
-                               throw new ObjectDisposedException ("StreamReader", "Cannot read from a closed StreamReader");
+                       CheckState ();
+
                        if (pos >= decoded_count && ReadBuffer () == 0)
                                return -1;
 
                        return decoded_buffer [pos++];
                }
 
-               public override int Read ([In, Out] char[] dest_buffer, int index, int count)
+               // Keep in sync with ReadAsync
+               public override int Read ([In, Out] char[] buffer, int index, int count)
                {
-                       if (base_stream == null)
-                               throw new ObjectDisposedException ("StreamReader", "Cannot read from a closed StreamReader");
-                       if (dest_buffer == null)
-                               throw new ArgumentNullException ("dest_buffer");
+                       if (buffer == null)
+                               throw new ArgumentNullException ("buffer");
                        if (index < 0)
                                throw new ArgumentOutOfRangeException ("index", "< 0");
                        if (count < 0)
                                throw new ArgumentOutOfRangeException ("count", "< 0");
                        // re-ordered to avoid possible integer overflow
-                       if (index > dest_buffer.Length - count)
-                               throw new ArgumentException ("index + count > dest_buffer.Length");
+                       if (index > buffer.Length - count)
+                               throw new ArgumentException ("index + count > buffer.Length");
+
+                       CheckState ();
 
                        int chars_read = 0;
-                       while (count > 0)
-                       {
+                       while (count > 0) {
                                if (pos >= decoded_count && ReadBuffer () == 0)
                                        return chars_read > 0 ? chars_read : 0;
 
                                int cch = Math.Min (decoded_count - pos, count);
-                               Array.Copy (decoded_buffer, pos, dest_buffer, index, cch);
+                               Array.Copy (decoded_buffer, pos, buffer, index, cch);
                                pos += cch;
                                index += cch;
                                count -= cch;
                                chars_read += cch;
+                               if (mayBlock)
+                                       break;
                        }
                        return chars_read;
                }
@@ -395,6 +507,10 @@ namespace System.IO {
                                        return res;
                                } else if (foundCR) {
                                        foundCR = false;
+                                       if (pos == 0)
+                                               return -2; // Need to flush the current buffered line.
+                                                          // This is a \r at the end of the previous decoded buffer that
+                                                          // is not followed by a \n in the current decoded buffer.
                                        return pos - 1;
                                }
 
@@ -404,10 +520,10 @@ namespace System.IO {
                        return -1;
                }
 
+               // Keep in sync with ReadLineAsync
                public override string ReadLine()
                {
-                       if (base_stream == null)
-                               throw new ObjectDisposedException ("StreamReader", "Cannot read from a closed StreamReader");
+                       CheckState ();
 
                        if (pos >= decoded_count && ReadBuffer () == 0)
                                return null;
@@ -416,6 +532,8 @@ namespace System.IO {
                        int end = FindNextEOL ();
                        if (end < decoded_count && end >= begin)
                                return new string (decoded_buffer, begin, end - begin);
+                       if (end == -2)
+                               return line_builder.ToString (0, line_builder.Length);
 
                        if (line_builder == null)
                                line_builder = new StringBuilder ();
@@ -447,24 +565,207 @@ namespace System.IO {
                                        }
                                        return line_builder.ToString (0, line_builder.Length);
                                }
+
+                               if (end == -2)
+                                       return line_builder.ToString (0, line_builder.Length);
                        }
                }
 
+               // Keep in sync with ReadToEndAsync
                public override string ReadToEnd()
+               {
+                       CheckState ();
+
+                       StringBuilder text = new StringBuilder ();
+
+                       do {
+                               text.Append (decoded_buffer, pos, decoded_count - pos);
+                       } while (ReadBuffer () != 0);
+
+                       return text.ToString ();
+               }
+
+               void CheckState ()
                {
                        if (base_stream == null)
                                throw new ObjectDisposedException ("StreamReader", "Cannot read from a closed StreamReader");
 
+#if NET_4_5
+                       if (async_task != null && !async_task.IsCompleted)
+                               throw new InvalidOperationException ();
+#endif
+               }
+
+#if NET_4_5
+               public override int ReadBlock ([In, Out] char[] buffer, int index, int count)
+               {
+                       if (buffer == null)
+                               throw new ArgumentNullException ("buffer");
+                       if (index < 0)
+                               throw new ArgumentOutOfRangeException ("index", "< 0");
+                       if (count < 0)
+                               throw new ArgumentOutOfRangeException ("count", "< 0");
+                       // re-ordered to avoid possible integer overflow
+                       if (index > buffer.Length - count)
+                               throw new ArgumentException ("index + count > buffer.Length");
+
+                       CheckState ();
+
+                       return base.ReadBlock (buffer, index, count);
+               }
+
+               public override Task<int> ReadAsync (char[] buffer, int index, int count)
+               {
+                       if (buffer == null)
+                               throw new ArgumentNullException ("buffer");
+                       if (index < 0)
+                               throw new ArgumentOutOfRangeException ("index", "< 0");
+                       if (count < 0)
+                               throw new ArgumentOutOfRangeException ("count", "< 0");
+                       // re-ordered to avoid possible integer overflow
+                       if (index > buffer.Length - count)
+                               throw new ArgumentException ("index + count > buffer.Length");
+
+                       CheckState ();
+
+                       DecoupledTask<int> res;
+                       async_task = res = new DecoupledTask<int> (ReadAsyncCore (buffer, index, count));
+                       return res.Task;
+               }
+
+               async Task<int> ReadAsyncCore (char[] buffer, int index, int count)
+               {
+                       int chars_read = 0;
+
+                       while (count > 0) {
+                               if (pos >= decoded_count && await ReadBufferAsync ().ConfigureAwait (false) == 0)
+                                       return chars_read > 0 ? chars_read : 0;
+
+                               int cch = Math.Min (decoded_count - pos, count);
+                               Array.Copy (decoded_buffer, pos, buffer, index, cch);
+                               pos += cch;
+                               index += cch;
+                               count -= cch;
+                               chars_read += cch;
+                               if (mayBlock)
+                                       break;
+                       }
+
+                       return chars_read;
+               }
+
+               public override Task<int> ReadBlockAsync (char[] buffer, int index, int count)
+               {
+                       if (buffer == null)
+                               throw new ArgumentNullException ("buffer");
+                       if (index < 0)
+                               throw new ArgumentOutOfRangeException ("index", "< 0");
+                       if (count < 0)
+                               throw new ArgumentOutOfRangeException ("count", "< 0");
+                       // re-ordered to avoid possible integer overflow
+                       if (index > buffer.Length - count)
+                               throw new ArgumentException ("index + count > buffer.Length");
+
+                       CheckState ();
+
+                       DecoupledTask<int> res;
+                       async_task = res = new DecoupledTask<int> (ReadAsyncCore (buffer, index, count));
+                       return res.Task;
+               }
+
+               public override Task<string> ReadLineAsync ()
+               {
+                       CheckState ();
+
+                       DecoupledTask<string> res;
+                       async_task = res = new DecoupledTask<string> (ReadLineAsyncCore ());
+                       return res.Task;
+               }
+
+               async Task<string> ReadLineAsyncCore ()
+               {
+                       if (pos >= decoded_count && await ReadBufferAsync ().ConfigureAwait (false) == 0)
+                               return null;
+
+                       int begin = pos;
+                       int end = FindNextEOL ();
+                       if (end < decoded_count && end >= begin)
+                               return new string (decoded_buffer, begin, end - begin);
+                       if (end == -2)
+                               return line_builder.ToString (0, line_builder.Length);
+
+                       if (line_builder == null)
+                               line_builder = new StringBuilder ();
+                       else
+                               line_builder.Length = 0;
+
+                       while (true) {
+                               if (foundCR) // don't include the trailing CR if present
+                                       decoded_count--;
+
+                               line_builder.Append (decoded_buffer, begin, decoded_count - begin);
+                               if (await ReadBufferAsync ().ConfigureAwait (false) == 0) {
+                                       if (line_builder.Capacity > 32768) {
+                                               StringBuilder sb = line_builder;
+                                               line_builder = null;
+                                               return sb.ToString (0, sb.Length);
+                                       }
+                                       return line_builder.ToString (0, line_builder.Length);
+                               }
+
+                               begin = pos;
+                               end = FindNextEOL ();
+                               if (end < decoded_count && end >= begin) {
+                                       line_builder.Append (decoded_buffer, begin, end - begin);
+                                       if (line_builder.Capacity > 32768) {
+                                               StringBuilder sb = line_builder;
+                                               line_builder = null;
+                                               return sb.ToString (0, sb.Length);
+                                       }
+                                       return line_builder.ToString (0, line_builder.Length);
+                               }
+
+                               if (end == -2)
+                                       return line_builder.ToString (0, line_builder.Length);
+                       }
+               }
+
+               public override Task<string> ReadToEndAsync ()
+               {
+                       CheckState ();
+
+                       DecoupledTask<string> res;
+                       async_task = res = new DecoupledTask<string> (ReadToEndAsyncCore ());
+                       return res.Task;
+               }
+
+               async Task<string> ReadToEndAsyncCore ()
+               {
                        StringBuilder text = new StringBuilder ();
 
-                       int size = decoded_buffer.Length;
-                       char [] buffer = new char [size];
-                       int len;
-                       
-                       while ((len = Read (buffer, 0, size)) > 0)
-                               text.Append (buffer, 0, len);
+                       do {
+                               text.Append (decoded_buffer, pos, decoded_count - pos);
+                       } while (await ReadBufferAsync () != 0);
 
                        return text.ToString ();
                }
+
+               async Task<int> ReadBufferAsync ()
+               {
+                       pos = 0;
+
+                       // keep looping until the decoder gives us some chars
+                       decoded_count = 0;
+                       do {
+                               var cbEncoded = await base_stream.ReadAsync (input_buffer, 0, buffer_size).ConfigureAwait (false);
+                               if (cbEncoded <= 0)
+                                       return 0;
+
+                               decoded_count = ReadBufferCore (cbEncoded);
+                       } while (decoded_count == 0);
+
+                       return decoded_count;
+               }
+#endif
        }
 }