ApplyCommand: add streams to read/write binary patch hunks

Add streams that can encode or decode git binary patch data on the fly.
Git writes binary patches base-85 encoded, at most 52 un-encoded bytes,
with the unencoded data length prefixed in a one-character encoding, and
suffixed with a newline character.

Add a test for both the new input and the output stream. The test
roundtrips binary data of different lengths in different ways.

Bug: 371725
Change-Id: Ic3faebaa4637520f5448b3d1acd78d5aaab3907a
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

1 files changed, 146 insertions, 0 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/io/BinaryHunkStreamTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/io/BinaryHunkStreamTest.java
new file mode 100644
index 0000000000..b198c32a78
--- /dev/null
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/io/BinaryHunkStreamTest.java
@@ -0,0 +1,146 @@
+/*
+ * Copyright (C) 2021 Thomas Wolf <thomas.wolf@paranor.ch> 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 static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.util.Arrays;
+
+import org.junit.Test;
+
+/**
+ * Tests for {@link BinaryHunkInputStream} and {@link BinaryHunkOutputStream}.
+ */
+public class BinaryHunkStreamTest {
+
+	@Test
+	public void testRoundtripWholeBuffer() throws IOException {
+		for (int length = 1; length < 520 + 52; length++) {
+			byte[] data = new byte[length];
+			for (int i = 0; i < data.length; i++) {
+				data[i] = (byte) (255 - (i % 256));
+			}
+			try (ByteArrayOutputStream bos = new ByteArrayOutputStream();
+					BinaryHunkOutputStream out = new BinaryHunkOutputStream(
+							bos)) {
+				out.write(data);
+				out.flush();
+				byte[] encoded = bos.toByteArray();
+				assertFalse(Arrays.equals(data, encoded));
+				try (BinaryHunkInputStream in = new BinaryHunkInputStream(
+						new ByteArrayInputStream(encoded))) {
+					byte[] decoded = new byte[data.length];
+					int newLength = in.read(decoded);
+					assertEquals(newLength, decoded.length);
+					assertEquals(-1, in.read());
+					assertArrayEquals(data, decoded);
+				}
+			}
+		}
+	}
+
+	@Test
+	public void testRoundtripChunks() throws IOException {
+		for (int length = 1; length < 520 + 52; length++) {
+			byte[] data = new byte[length];
+			for (int i = 0; i < data.length; i++) {
+				data[i] = (byte) (255 - (i % 256));
+			}
+			try (ByteArrayOutputStream bos = new ByteArrayOutputStream();
+					BinaryHunkOutputStream out = new BinaryHunkOutputStream(
+							bos)) {
+				out.write(data, 0, data.length / 2);
+				out.write(data, data.length / 2, data.length - data.length / 2);
+				out.flush();
+				byte[] encoded = bos.toByteArray();
+				assertFalse(Arrays.equals(data, encoded));
+				try (BinaryHunkInputStream in = new BinaryHunkInputStream(
+						new ByteArrayInputStream(encoded))) {
+					byte[] decoded = new byte[data.length];
+					int p = 0;
+					int n;
+					while ((n = in.read(decoded, p,
+							Math.min(decoded.length - p, 57))) >= 0) {
+						p += n;
+						if (p == decoded.length) {
+							break;
+						}
+					}
+					assertEquals(p, decoded.length);
+					assertEquals(-1, in.read());
+					assertArrayEquals(data, decoded);
+				}
+			}
+		}
+	}
+
+	@Test
+	public void testRoundtripBytes() throws IOException {
+		for (int length = 1; length < 520 + 52; length++) {
+			byte[] data = new byte[length];
+			for (int i = 0; i < data.length; i++) {
+				data[i] = (byte) (255 - (i % 256));
+			}
+			try (ByteArrayOutputStream bos = new ByteArrayOutputStream();
+					BinaryHunkOutputStream out = new BinaryHunkOutputStream(
+							bos)) {
+				for (int i = 0; i < data.length; i++) {
+					out.write(data[i]);
+				}
+				out.flush();
+				byte[] encoded = bos.toByteArray();
+				assertFalse(Arrays.equals(data, encoded));
+				try (BinaryHunkInputStream in = new BinaryHunkInputStream(
+						new ByteArrayInputStream(encoded))) {
+					byte[] decoded = new byte[data.length];
+					for (int i = 0; i < decoded.length; i++) {
+						int val = in.read();
+						assertTrue(0 <= val && val <= 255);
+						decoded[i] = (byte) val;
+					}
+					assertEquals(-1, in.read());
+					assertArrayEquals(data, decoded);
+				}
+			}
+		}
+	}
+
+	@Test
+	public void testRoundtripWithClose() throws IOException {
+		for (int length = 1; length < 520 + 52; length++) {
+			byte[] data = new byte[length];
+			for (int i = 0; i < data.length; i++) {
+				data[i] = (byte) (255 - (i % 256));
+			}
+			try (ByteArrayOutputStream bos = new ByteArrayOutputStream()) {
+				try (BinaryHunkOutputStream out = new BinaryHunkOutputStream(
+						bos)) {
+					out.write(data);
+				}
+				byte[] encoded = bos.toByteArray();
+				assertFalse(Arrays.equals(data, encoded));
+				try (BinaryHunkInputStream in = new BinaryHunkInputStream(
+						new ByteArrayInputStream(encoded))) {
+					byte[] decoded = new byte[data.length];
+					int newLength = in.read(decoded);
+					assertEquals(newLength, decoded.length);
+					assertEquals(-1, in.read());
+					assertArrayEquals(data, decoded);
+				}
+			}
+		}
+	}
+}