Initial Commit

iTechSharp/srcbc/asn1/DefiniteLengthInputStream.cs

@@ -0,0 +1,86 @@
+using System;
+using System.IO;
+
+using Org.BouncyCastle.Utilities.IO;
+
+namespace Org.BouncyCastle.Asn1
+{
+    class DefiniteLengthInputStream
+        : LimitedInputStream
+    {
+		private static readonly byte[] EmptyBytes = new byte[0];
+
+		private int _length;
+
+        internal DefiniteLengthInputStream(
+            Stream	inStream,
+            int		length)
+            : base(inStream)
+        {
+			if (length < 0)
+				throw new ArgumentException("negative lengths not allowed", "length");
+
+			this._length = length;
+        }
+
+		public override int ReadByte()
+        {
+            if (_length > 0)
+            {
+				int b = _in.ReadByte();
+
+				if (b < 0)
+					throw new EndOfStreamException();
+
+				--_length;
+				return b;
+            }
+
+			SetParentEofDetect(true);
+
+			return -1;
+        }
+
+		public override int Read(
+			byte[]	buf,
+			int		off,
+			int		len)
+		{
+			if (_length > 0)
+			{
+				int toRead = System.Math.Min(len, _length);
+				int numRead = _in.Read(buf, off, toRead);
+
+				if (numRead < 1)
+					throw new EndOfStreamException();
+
+				_length -= numRead;
+				return numRead;
+			}
+
+			SetParentEofDetect(true);
+
+			return 0;
+		}
+
+		internal byte[] ToArray()
+		{
+			byte[] bytes;
+			if (_length > 0)
+			{
+				bytes = new byte[_length];
+				if (Streams.ReadFully(_in, bytes) < _length)
+					throw new EndOfStreamException();
+				_length = 0;
+			}
+			else
+			{
+				bytes = EmptyBytes;
+			}
+
+			SetParentEofDetect(true);
+
+			return bytes;
+		}
+    }
+}