Initial Commit

iTechSharp/srcbc/asn1/IndefiniteLengthInputStream.cs

@@ -0,0 +1,95 @@
+using System.IO;
+
+namespace Org.BouncyCastle.Asn1
+{
+    class IndefiniteLengthInputStream
+        : LimitedInputStream
+    {
+        private int     _b1;
+        private int     _b2;
+        private bool _eofReached = false;
+        private bool _eofOn00 = true;
+
+        internal IndefiniteLengthInputStream(
+            Stream inStream)
+            : base(inStream)
+        {
+            _b1 = inStream.ReadByte();
+            _b2 = inStream.ReadByte();
+            _eofReached = (_b2 < 0);
+        }
+
+        internal void SetEofOn00(
+            bool eofOn00)
+        {
+            _eofOn00 = eofOn00;
+        }
+
+        internal bool CheckForEof()
+        {
+            if (_eofOn00 && (_b1 == 0x00 && _b2 == 0x00))
+            {
+                _eofReached = true;
+                SetParentEofDetect(true);
+            }
+
+			return _eofReached;
+        }
+
+		public override int Read(
+			byte[]	buffer,
+			int		offset,
+			int		count)
+		{
+			// Only use this optimisation if we aren't checking for 00
+			if (_eofOn00 || count < 3)
+				return base.Read(buffer, offset, count);
+
+			if (_eofReached)
+				return 0;
+
+			int numRead = _in.Read(buffer, offset + 2, count - 2);
+
+			if (numRead <= 0)
+			{
+				// Corrupted stream
+				throw new EndOfStreamException();
+			}
+
+			buffer[offset] = (byte)_b1;
+			buffer[offset + 1] = (byte)_b2;
+
+			_b1 = _in.ReadByte();
+			_b2 = _in.ReadByte();
+
+			if (_b2 < 0)
+			{
+				// Corrupted stream
+				throw new EndOfStreamException();
+			}
+
+			return numRead + 2;
+		}
+
+		public override int ReadByte()
+        {
+            if (CheckForEof())
+                return -1;
+
+			int b = _in.ReadByte();
+
+			if (b < 0)
+            {
+				// Corrupted stream
+				throw new EndOfStreamException();
+            }
+
+			int v = _b1;
+
+            _b1 = _b2;
+            _b2 = b;
+
+            return v;
+        }
+    }
+}