1 files changed, 47 insertions, 0 deletions
diff --git a/crypto/src/util/io/BaseInputStream.cs b/crypto/src/util/io/BaseInputStream.cs
new file mode 100644
index 000000000..3ff4a1957
--- /dev/null
+++ b/crypto/src/util/io/BaseInputStream.cs
@@ -0,0 +1,47 @@
+using System;
+using System.Diagnostics;
+using System.IO;
+
+namespace Org.BouncyCastle.Utilities.IO
+{
+    public abstract class BaseInputStream : Stream
+    {
+		private bool closed;
+
+		public sealed override bool CanRead { get { return !closed; } }
+        public sealed override bool CanSeek { get { return false; } }
+        public sealed override bool CanWrite { get { return false; } }
+		public override void Close() { closed = true; }
+		public sealed override void Flush() {}
+        public sealed override long Length { get { throw new NotSupportedException(); } }
+        public sealed override long Position
+        {
+            get { throw new NotSupportedException(); }
+            set { throw new NotSupportedException(); }
+        }
+
+        public override int Read(byte[] buffer, int offset, int count)
+        {
+            int pos = offset;
+            try
+            {
+                int end = offset + count;
+                while (pos < end)
+                {
+                    int b = ReadByte();
+                    if (b == -1) break;
+                    buffer[pos++] = (byte) b;
+                }
+            }
+            catch (IOException)
+            {
+                if (pos == offset) throw;
+            }
+            return pos - offset;
+        }
+
+        public sealed override long Seek(long offset, SeekOrigin origin) { throw new NotSupportedException(); }
+        public sealed override void SetLength(long value) { throw new NotSupportedException(); }
+        public sealed override void Write(byte[] buffer, int offset, int count) { throw new NotSupportedException(); }
+    }
+}