1 files changed, 58 insertions, 0 deletions
diff --git a/crypto/src/util/io/LimitedBuffer.cs b/crypto/src/util/io/LimitedBuffer.cs
new file mode 100644
index 000000000..07c9969ad
--- /dev/null
+++ b/crypto/src/util/io/LimitedBuffer.cs
@@ -0,0 +1,58 @@
+using System;
+
+namespace Org.BouncyCastle.Utilities.IO
+{
+    public sealed class LimitedBuffer
+        : BaseOutputStream
+    {
+        private readonly byte[] m_buf;
+        private int m_count;
+
+        public LimitedBuffer(int limit)
+        {
+            m_buf = new byte[limit];
+            m_count = 0;
+        }
+
+        public int CopyTo(byte[] buffer, int offset)
+        {
+            Array.Copy(m_buf, 0, buffer, offset, m_count);
+            return m_count;
+        }
+
+#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+        public int CopyTo(Span<byte> buffer)
+        {
+            m_buf.AsSpan(0, m_count).CopyTo(buffer);
+            return m_count;
+        }
+#endif
+
+        public int Count => m_count;
+
+        public int Limit => m_buf.Length;
+
+        public void Reset()
+        {
+            m_count = 0;
+        }
+
+        public override void Write(byte[] buffer, int offset, int count)
+        {
+            Array.Copy(buffer, offset, m_buf, m_count, count);
+            m_count += count;
+        }
+
+#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+        public override void Write(ReadOnlySpan<byte> buffer)
+        {
+            buffer.CopyTo(m_buf.AsSpan(m_count));
+        }
+#endif
+
+        public override void WriteByte(byte value)
+        {
+            m_buf[m_count++] = value;
+        }
+    }
+}