Merge "Extend FileUtils.rename to common git semantics"

org.eclipse.jgit.test/tst/org/eclipse/jgit/util/FileUtilTest.java

@@ -45,6 +45,7 @@ package org.eclipse.jgit.util;
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.endsWith;
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
@@ -52,6 +53,7 @@ import static org.junit.Assert.fail;
 import java.io.File;
 import java.io.IOException;
 
+import org.eclipse.jgit.junit.JGitTestUtil;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
@@ -321,4 +323,71 @@ public class FileUtilTest {
 		assertTrue(f.exists());
 		assertFalse(e.exists());
 	}
+
+	@Test
+	public void testRenameOverNonExistingFile() throws IOException {
+		File d = new File(trash, "d");
+		FileUtils.mkdirs(d);
+		File f1 = new File(trash, "d/f");
+		File f2 = new File(trash, "d/g");
+		JGitTestUtil.write(f1, "f1");
+		// test
+		FileUtils.rename(f1, f2);
+		assertFalse(f1.exists());
+		assertTrue(f2.exists());
+		assertEquals("f1", JGitTestUtil.read(f2));
+	}
+
+	@Test
+	public void testRenameOverExistingFile() throws IOException {
+		File d = new File(trash, "d");
+		FileUtils.mkdirs(d);
+		File f1 = new File(trash, "d/f");
+		File f2 = new File(trash, "d/g");
+		JGitTestUtil.write(f1, "f1");
+		JGitTestUtil.write(f2, "f2");
+		// test
+		FileUtils.rename(f1, f2);
+		assertFalse(f1.exists());
+		assertTrue(f2.exists());
+		assertEquals("f1", JGitTestUtil.read(f2));
+	}
+
+	@Test
+	public void testRenameOverExistingNonEmptyDirectory() throws IOException {
+		File d = new File(trash, "d");
+		FileUtils.mkdirs(d);
+		File f1 = new File(trash, "d/f");
+		File f2 = new File(trash, "d/g");
+		File d1 = new File(trash, "d/g/h/i");
+		File f3 = new File(trash, "d/g/h/f");
+		FileUtils.mkdirs(d1);
+		JGitTestUtil.write(f1, "f1");
+		JGitTestUtil.write(f3, "f3");
+		// test
+		try {
+			FileUtils.rename(f1, f2);
+			fail("rename to non-empty directory should fail");
+		} catch (IOException e) {
+			assertEquals("f1", JGitTestUtil.read(f1)); // untouched source
+			assertEquals("f3", JGitTestUtil.read(f3)); // untouched
+			// empty directories within f2 may or may not have been deleted
+		}
+	}
+
+	@Test
+	public void testRenameOverExistingEmptyDirectory() throws IOException {
+		File d = new File(trash, "d");
+		FileUtils.mkdirs(d);
+		File f1 = new File(trash, "d/f");
+		File f2 = new File(trash, "d/g");
+		File d1 = new File(trash, "d/g/h/i");
+		FileUtils.mkdirs(d1);
+		JGitTestUtil.write(f1, "f1");
+		// test
+		FileUtils.rename(f1, f2);
+		assertFalse(f1.exists());
+		assertTrue(f2.exists());
+		assertEquals("f1", JGitTestUtil.read(f2));
+	}
 }

org.eclipse.jgit/src/org/eclipse/jgit/util/FileUtils.java

@@ -171,7 +171,14 @@ public class FileUtils {
 	 * Rename a file or folder. If the rename fails and if we are running on a
 	 * filesystem where it makes sense to repeat a failing rename then repeat
 	 * the rename operation up to 9 times with 100ms sleep time between two
-	 * calls
+	 * calls. Furthermore if the destination exists and is directory hierarchy
+	 * with only directories in it, the whole directory hierarchy will be
+	 * deleted. If the target represents a non-empty directory structure, empty
+	 * subdirectories within that structure may or may not be deleted even if
+	 * the method fails. Furthermore if the destination exists and is a file
+	 * then the file will be deleted and then the rename is retried.
+	 * <p>
+	 * This operation is <em>not</me> atomic.
 	 *
 	 * @see FS#retryFailedLockFileCommit()
 	 * @param src
@@ -188,6 +195,15 @@ public class FileUtils {
 		while (--attempts >= 0) {
 			if (src.renameTo(dst))
 				return;
+			try {
+				if (!dst.delete())
+					delete(dst, EMPTY_DIRECTORIES_ONLY | RECURSIVE);
+				// On *nix there is no try, you do or do not
+				if (src.renameTo(dst))
+					return;
+			} catch (IOException e) {
+				// ignore and continue retry
+			}
 			try {
 				Thread.sleep(100);
 			} catch (InterruptedException e) {