1 files changed, 56 insertions, 0 deletions
diff --git a/crypto/src/util/io/LimitedInputStream.cs b/crypto/src/util/io/LimitedInputStream.cs
new file mode 100644
index 000000000..d6616eff5
--- /dev/null
+++ b/crypto/src/util/io/LimitedInputStream.cs
@@ -0,0 +1,56 @@
+using Org.BouncyCastle.Utilities.Zlib;
+using System;
+using System.IO;
+
+namespace Org.BouncyCastle.Utilities.IO
+{
+ internal class LimitedInputStream
+ : BaseInputStream
+ {
+ private readonly Stream m_stream;
+ private long m_limit;
+
+ internal LimitedInputStream(Stream stream, long limit)
+ {
+ this.m_stream = stream;
+ this.m_limit = limit;
+ }
+
+ internal long CurrentLimit => m_limit;
+
+ public override int Read(byte[] buffer, int offset, int count)
+ {
+ int numRead = m_stream.Read(buffer, offset, count);
+ if (numRead > 0)
+ {
+ if ((m_limit -= numRead) < 0)
+ throw new StreamOverflowException("Data Overflow");
+ }
+ return numRead;
+ }
+
+#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
+ public override int Read(Span<byte> buffer)
+ {
+ int numRead = m_stream.Read(buffer);
+ if (numRead > 0)
+ {
+ if ((m_limit -= numRead) < 0)
+ throw new StreamOverflowException("Data Overflow");
+ }
+ return numRead;
+ }
+#endif
+
+ public override int ReadByte()
+ {
+ int b = m_stream.ReadByte();
+ if (b >= 0)
+ {
+ if (--m_limit < 0)
+ throw new StreamOverflowException("Data Overflow");
+ }
+ return b;
+ }
+ }
+}
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