[errorprone] FS#searchPath: handle surprising behavior of String#split

See https://errorprone.info/bugpattern/StringSplitter

Change-Id: Ic80f6c53ea96537ed4d046621e774288fced7ce1

2 files changed, 29 insertions, 1 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/FSTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/FSTest.java
index 171d80c3da..51236e1cc0 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/FSTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/FSTest.java
@@ -13,6 +13,7 @@ package org.eclipse.jgit.util;
 import static java.time.Instant.EPOCH;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assume.assumeNoException;
 import static org.junit.Assume.assumeTrue;
@@ -233,4 +234,26 @@ public class FSTest {
 		assertFalse(RepositoryCache.FileKey
 				.isGitRepository(new File("repo.git"), FS.DETECTED));
 	}
+
+	@Test
+	public void testSearchPath() throws IOException {
+		File f1 = new File(trash, "file1");
+		FileUtils.createNewFile(f1);
+		f1.setExecutable(true);
+		File f2 = new File(trash, "file2");
+		FileUtils.createNewFile(f2);
+		assertEquals(f1, FS.searchPath(trash.getAbsolutePath(), "file1"));
+		assertNull(FS.searchPath(trash.getAbsolutePath(), "file2"));
+	}
+
+	@Test
+	public void testSearchPathEmptyPath() {
+		assertNull(FS.searchPath("", "file1"));
+		assertNull(FS.searchPath(File.pathSeparator, "file1"));
+		assertNull(FS.searchPath(File.pathSeparator + File.pathSeparator,
+				"file1"));
+		assertNull(FS.searchPath(
+				" " + File.pathSeparator + " " + File.pathSeparator + " \t",
+				"file1"));
+	}
 }
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/util/FS.java b/org.eclipse.jgit/src/org/eclipse/jgit/util/FS.java
index eadd34c3d3..203669eb7a 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/util/FS.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/util/FS.java
@@ -97,6 +97,9 @@ public abstract class FS {
 	private static final Pattern VERSION = Pattern
 			.compile("\\s(\\d+)\\.(\\d+)\\.(\\d+)"); //$NON-NLS-1$
 
+	private static final Pattern EMPTY_PATH = Pattern
+			.compile("^[\\p{javaWhitespace}" + File.pathSeparator + "]*$"); //$NON-NLS-1$ //$NON-NLS-2$
+
 	private volatile Boolean supportSymlinks;
 
 	/**
@@ -1310,8 +1313,10 @@ public abstract class FS {
 	 * @return the first match found, or null
 	 * @since 3.0
 	 */
+	@SuppressWarnings("StringSplitter")
 	protected static File searchPath(String path, String... lookFor) {
-		if (path == null) {
+		if (StringUtils.isEmptyOrNull(path)
+				|| EMPTY_PATH.matcher(path).find()) {
 			return null;
 		}