Clean VanillaJavaBuilder output directories

to ensure outputs from any previous local builds are discarded.

To cherry-pick for bazelbuild#2692.

Fixes bazelbuild#2941

PiperOrigin-RevId: 155089391

src/java_tools/buildjar/java/com/google/devtools/build/buildjar/VanillaJavaBuilder.java

@@ -249,12 +249,12 @@ private static void setLocations(OptionsParser optionsParser, StandardJavaFileMa
  StandardLocation.ANNOTATION_PROCESSOR_PATH, toFiles(optionsParser.getProcessorPath()));
  if (optionsParser.getSourceGenDir() != null) {
  Path sourceGenDir = Paths.get(optionsParser.getSourceGenDir());
- Files.createDirectories(sourceGenDir);
+ createOutputDirectory(sourceGenDir);
  fileManager.setLocation(
  StandardLocation.SOURCE_OUTPUT, ImmutableList.of(sourceGenDir.toFile()));
  }
  Path classDir = Paths.get(optionsParser.getClassDir());
- Files.createDirectories(classDir);
+ createOutputDirectory(classDir);
  fileManager.setLocation(StandardLocation.CLASS_OUTPUT, ImmutableList.of(classDir.toFile()));
  }
 
@@ -342,4 +342,32 @@ public CharSequence getCharContent(boolean ignoreEncodingErrors) throws IOExcept
  return new String(Files.readAllBytes(path), UTF_8);
  }
  }
+
+ private static void createOutputDirectory(Path dir) throws IOException {
+ if (Files.exists(dir)) {
+ try {
+ // TODO(b/27069912): handle symlinks
+ Files.walkFileTree(
+ dir,
+ new SimpleFileVisitor<Path>() {
+ @Override
+ public FileVisitResult visitFile(Path file, BasicFileAttributes attrs)
+ throws IOException {
+ Files.delete(file);
+ return FileVisitResult.CONTINUE;
+ }
+
+ @Override
+ public FileVisitResult postVisitDirectory(Path dir, IOException exc)
+ throws IOException {
+ Files.delete(dir);
+ return FileVisitResult.CONTINUE;
+ }
+ });
+ } catch (IOException e) {
+ throw new IOException("Cannot clean output directory '" + dir + "'", e);
+ }
+ }
+ Files.createDirectories(dir);
+ }
 }

src/java_tools/buildjar/javatests/com/google/devtools/build/buildjar/VanillaJavaBuilderTest.java

@@ -183,4 +183,55 @@ public void diagnosticWithoutSource() throws Exception {
  assertThat(result.ok()).isFalse();
  assertThat(Files.exists(output)).isFalse();
  }
+
+ @Test
+ public void cleanOutputDirectories() throws Exception {
+ Path source = temporaryFolder.newFile("Test.java").toPath();
+ Path output = temporaryFolder.newFile("out.jar").toPath();
+ Files.write(
+ source,
+ ImmutableList.of(
+ "class A {", //
+ "}"),
+ UTF_8);
+ Path sourceJar = temporaryFolder.newFile("src.srcjar").toPath();
+ try (OutputStream os = Files.newOutputStream(sourceJar);
+ JarOutputStream jos = new JarOutputStream(os)) {
+ jos.putNextEntry(new JarEntry("B.java"));
+ jos.write("class B {}".getBytes(UTF_8));
+ }
+ Path resource = temporaryFolder.newFile("resource.properties").toPath();
+ Files.write(resource, "hello".getBytes(UTF_8));
+
+ Path classDir = temporaryFolder.newFolder().toPath();
+ Files.write(
+ classDir.resolve("extra.class"),
+ new byte[] {(byte) 0xca, (byte) 0xfe, (byte) 0xba, (byte) 0xbe});
+
+ VanillaJavaBuilderResult result =
+ run(
+ ImmutableList.of(
+ "--javacopts",
+ "-Xep:FallThrough:ERROR",
+ "--sources",
+ source.toString(),
+ "--source_jars",
+ sourceJar.toString(),
+ "--output",
+ output.toString(),
+ "--classpath_resources",
+ resource.toString(),
+ "--bootclasspath",
+ Paths.get(System.getProperty("java.home")).resolve("lib/rt.jar").toString(),
+ "--classdir",
+ classDir.toString()));
+
+ assertThat(result.output()).isEmpty();
+ assertThat(result.ok()).isTrue();
+
+ ImmutableMap<String, byte[]> outputEntries = readJar(output.toFile());
+ assertThat(outputEntries.keySet())
+ .containsExactly(
+ "META-INF/", "META-INF/MANIFEST.MF", "A.class", "B.class", "resource.properties");
+ }
 }