1 files changed, 135 insertions, 0 deletions
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/util/io/ByteBufferInputStream.java b/org.eclipse.jgit/src/org/eclipse/jgit/util/io/ByteBufferInputStream.java
new file mode 100644
index 0000000000..9c00329ba1
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/util/io/ByteBufferInputStream.java
@@ -0,0 +1,135 @@
+/*
+ * Copyright (C) 2023, SAP SE and others
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Distribution License v. 1.0 which is available at
+ * https://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+package org.eclipse.jgit.util.io;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.ByteBuffer;
+import java.nio.InvalidMarkException;
+import java.util.Objects;
+
+import org.eclipse.jgit.annotations.NonNull;
+import org.eclipse.jgit.internal.JGitText;
+
+/**
+ * An {@link InputStream} backed by a {@link ByteBuffer}.
+ */
+public class ByteBufferInputStream extends InputStream {
+
+	private ByteBuffer buf;
+
+	/**
+	 * Creates a {@link ByteBufferInputStream}
+	 *
+	 * @param buf
+	 *            the ByteBuffer backing the stream
+	 */
+	public ByteBufferInputStream(@NonNull ByteBuffer buf) {
+		this.buf = buf;
+	}
+
+	@Override
+	public int read() throws IOException {
+		nullCheck();
+		if (buf.hasRemaining()) {
+			return buf.get() & 0xFF;
+		}
+		return -1;
+	}
+
+	@Override
+	public int read(byte[] b) throws IOException {
+		nullCheck();
+		return read(b, 0, b.length);
+	}
+
+	@Override
+	public int read(byte[] b, int off, int len) throws IOException {
+		nullCheck();
+		Objects.checkFromIndexSize(off, len, b.length);
+		if (len == 0) {
+			return 0;
+		}
+		int length = Math.min(buf.remaining(), len);
+		if (length == 0) {
+			return -1;
+		}
+		buf.get(b, off, length);
+		return length;
+	}
+
+	@Override
+	public byte[] readAllBytes() throws IOException {
+		return readNBytes(buf.remaining());
+	}
+
+	@Override
+	public byte[] readNBytes(int len) throws IOException {
+		int l = Math.min(len, buf.remaining());
+		byte[] b = new byte[l];
+		read(b);
+		return b;
+	}
+
+	@Override
+	public int readNBytes(byte[] b, int off, int len) throws IOException {
+		return read(b, off, len);
+	}
+
+	@Override
+	public long skip(long n) throws IOException {
+		nullCheck();
+		if (n <= 0) {
+			return 0;
+		}
+		// ByteBuffer index has type int
+		int delta = n > Integer.MAX_VALUE ? buf.remaining()
+				: Math.min((int) n, buf.remaining());
+		buf.position(buf.position() + delta);
+		return delta;
+	}
+
+	@Override
+	public int available() throws IOException {
+		nullCheck();
+		return buf.remaining();
+	}
+
+	@Override
+	public void close() {
+		buf = null;
+	}
+
+	@Override
+	public synchronized void mark(int readlimit) {
+		buf.mark();
+	}
+
+	@Override
+	public synchronized void reset() throws IOException {
+		try {
+			buf.reset();
+		} catch (InvalidMarkException e) {
+			throw new IOException(e);
+		}
+	}
+
+	@Override
+	public boolean markSupported() {
+		return true;
+	}
+
+	private void nullCheck() throws IOException {
+		if (buf == null) {
+			throw new IOException(JGitText.get().inputStreamClosed);
+		}
+	}
+}