BatchingProgressMonitor: avoid int overflow when computing percentage

When cloning huge repositories I observed percentage of object counts
turning negative. This happened if lastWork * 100 exceeded
Integer.MAX_VALUE.

Change-Id: Ic5f5cf5a911a91338267aace4daba4b873ab3900

2 files changed, 86 insertions, 3 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/TextProgressMonitorTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/TextProgressMonitorTest.java
new file mode 100644
index 0000000000..55ca2cdea3
--- /dev/null
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/TextProgressMonitorTest.java
@@ -0,0 +1,83 @@
+/*
+ * Copyright (C) 2023, SAP SE or an SAP affiliate company 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.lib;
+
+import java.io.ByteArrayOutputStream;
+import java.io.OutputStreamWriter;
+import java.io.UnsupportedEncodingException;
+import java.nio.charset.StandardCharsets;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+public class TextProgressMonitorTest {
+
+	private TextProgressMonitor m;
+
+	private ByteArrayOutputStream buf;
+
+	@Before
+	public void setup() {
+		buf = new ByteArrayOutputStream();
+		m = new TextProgressMonitor(
+				new OutputStreamWriter(buf, StandardCharsets.UTF_8));
+	}
+
+	@Test
+	public void testSimple() throws Exception {
+		m.beginTask("task", 10);
+		for (int i = 0; i < 10; i++) {
+			m.update(1);
+		}
+		m.endTask();
+		Assert.assertArrayEquals(
+				new String[] { "", "task:                    10% ( 1/10)",
+						"task:                    20% ( 2/10)",
+						"task:                    30% ( 3/10)",
+						"task:                    40% ( 4/10)",
+						"task:                    50% ( 5/10)",
+						"task:                    60% ( 6/10)",
+						"task:                    70% ( 7/10)",
+						"task:                    80% ( 8/10)",
+						"task:                    90% ( 9/10)",
+						"task:                   100% (10/10)",
+						"task:                   100% (10/10)\n" },
+				bufLines());
+	}
+
+	@Test
+	public void testLargeNumbers() throws Exception {
+		m.beginTask("task", 1_000_000_000);
+		for (int i = 0; i < 10; i++) {
+			m.update(100_000_000);
+		}
+		m.endTask();
+		Assert.assertArrayEquals(
+				new String[] { "",
+						"task:                    10% ( 100000000/1000000000)",
+						"task:                    20% ( 200000000/1000000000)",
+						"task:                    30% ( 300000000/1000000000)",
+						"task:                    40% ( 400000000/1000000000)",
+						"task:                    50% ( 500000000/1000000000)",
+						"task:                    60% ( 600000000/1000000000)",
+						"task:                    70% ( 700000000/1000000000)",
+						"task:                    80% ( 800000000/1000000000)",
+						"task:                    90% ( 900000000/1000000000)",
+						"task:                   100% (1000000000/1000000000)",
+						"task:                   100% (1000000000/1000000000)\n" },
+				bufLines());
+	}
+
+	String[] bufLines() throws UnsupportedEncodingException {
+		String s = new String(buf.toString(StandardCharsets.UTF_8.name()));
+		return s.split("\r");
+	}
+}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/lib/BatchingProgressMonitor.java b/org.eclipse.jgit/src/org/eclipse/jgit/lib/BatchingProgressMonitor.java
index 2caefa4d97..49e295aed8 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/lib/BatchingProgressMonitor.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/lib/BatchingProgressMonitor.java
@@ -176,7 +176,7 @@ public abstract class BatchingProgressMonitor implements ProgressMonitor {
 				}
 			} else {
 				// Display once per second or when 1% is done.
-				int currPercent = lastWork * 100 / totalWork;
+				int currPercent = Math.round(lastWork * 100F / totalWork);
 				if (display) {
 					pm.onUpdate(taskName, lastWork, totalWork, currPercent);
 					output = true;
@@ -201,8 +201,8 @@ public abstract class BatchingProgressMonitor implements ProgressMonitor {
 				if (totalWork == UNKNOWN) {
 					pm.onEndTask(taskName, lastWork);
 				} else {
-					int pDone = lastWork * 100 / totalWork;
-					pm.onEndTask(taskName, lastWork, totalWork, pDone);
+					int currPercent = Math.round(lastWork * 100F / totalWork);
+					pm.onEndTask(taskName, lastWork, totalWork, currPercent);
 				}
 			}
 			if (timerFuture != null)