Prevent ijar from stripping out .kotlin_module files, which are neede…

…d for extension functions.

PiperOrigin-RevId: 198579700

third_party/ijar/ijar.cc

@@ -35,6 +35,8 @@ bool StripClass(u1 *&classdata_out, const u1 *classdata_in, size_t in_length);
 
 const char *CLASS_EXTENSION = ".class";
 const size_t CLASS_EXTENSION_LENGTH = strlen(CLASS_EXTENSION);
+const char *KOTLIN_MODULE_EXTENSION = ".kotlin_module";
+const size_t KOTLIN_MODULE_EXTENSION_LENGTH = strlen(KOTLIN_MODULE_EXTENSION);
 
 const char *MANIFEST_DIR_PATH = "META-INF/";
 const size_t MANIFEST_DIR_PATH_LENGTH = strlen(MANIFEST_DIR_PATH);
@@ -81,8 +83,29 @@ class JarStripperProcessor : public JarExtractorProcessor {
                              const char *injecting_rule_kind);
 };
 
+static bool StartsWith(const char *str, const size_t str_len,
+                       const char *prefix, const size_t prefix_len) {
+  return str_len >= prefix_len && strncmp(str, prefix, prefix_len) == 0;
+}
+
+static bool EndsWith(const char *str, const size_t str_len, const char *suffix,
+                     const size_t suffix_len) {
+  return str_len >= suffix_len &&
+         strcmp(str + str_len - suffix_len, suffix) == 0;
+}
+
+static bool IsKotlinModule(const char *filename, const size_t filename_len) {
+  return StartsWith(filename, filename_len, MANIFEST_DIR_PATH,
+                    MANIFEST_DIR_PATH_LENGTH) &&
+         EndsWith(filename, filename_len, KOTLIN_MODULE_EXTENSION,
+                  KOTLIN_MODULE_EXTENSION_LENGTH);
+}
+
 bool JarStripperProcessor::Accept(const char *filename, const u4 /*attr*/) {
   const size_t filename_len = strlen(filename);
+  if (IsKotlinModule(filename, filename_len)) {
+    return true;
+  }
   if (filename_len < CLASS_EXTENSION_LENGTH ||
       strcmp(filename + filename_len - CLASS_EXTENSION_LENGTH,
              CLASS_EXTENSION) != 0) {
@@ -106,7 +129,7 @@ void JarStripperProcessor::Process(const char *filename, const u4 /*attr*/,
   if (verbose) {
     fprintf(stderr, "INFO: StripClass: %s\n", filename);
   }
-  if (IsModuleInfo(filename)) {
+  if (IsModuleInfo(filename) || IsKotlinModule(filename, strlen(filename))) {
     u1 *q = builder_->NewFile(filename, 0);
     memcpy(q, data, size);
     builder_->FinishFile(size, /* compress: */ false, /* compute_crc: */ true);

third_party/ijar/test/BUILD

@@ -223,6 +223,31 @@ genrule(
     tools = ["//third_party/ijar"],
 )
 
+java_binary(
+    name = "GenKotlinModule",
+    testonly = 1,
+    srcs = ["GenKotlinModule.java"],
+    main_class = "GenKotlinModule",
+    deps = ["//third_party:guava"],
+)
+
+genrule(
+    name = "kotlin_module",
+    testonly = 1,
+    outs = ["kotlin_module.jar"],
+    cmd = "$(location :GenKotlinModule) $@",
+    tools = [":GenKotlinModule"],
+)
+
+genrule(
+    name = "kotlin_module_interface",
+    testonly = 1,
+    srcs = [":kotlin_module.jar"],
+    outs = ["kotlin_module-interface.jar"],
+    cmd = "$(location //third_party/ijar) $< $@",
+    tools = ["//third_party/ijar"],
+)
+
 java_test(
     name = "IjarTests",
     size = "small",
@@ -247,6 +272,7 @@ java_test(
         ":jar_with_manifest_nostrip",
         ":jar_without_manifest_nostrip",
         ":jar_without_manifest_nostrip_idempotence",
+        ":kotlin_module-interface.jar",
         ":liblocal_and_anonymous_lib.jar",
         ":local_and_anonymous-interface.jar",
         ":module_info-interface.jar",

third_party/ijar/test/GenKotlinModule.java

@@ -0,0 +1,41 @@
+// Copyright 2017 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import com.google.common.io.ByteStreams;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.jar.JarOutputStream;
+import java.util.zip.ZipEntry;
+
+/** A generator for a jar file containing a .kotlin-module file, and one real class file. */
+public class GenKotlinModule {
+  public static void main(String[] args) throws IOException {
+    try (JarOutputStream jos = new JarOutputStream(Files.newOutputStream(Paths.get(args[0])))) {
+      addEntry(jos, "META-INF/bar.kotlin_module");
+      jos.write("hello".getBytes(UTF_8));
+
+      addEntry(jos, "java/lang/String.class");
+      ByteStreams.copy(String.class.getResourceAsStream("/java/lang/String.class"), jos);
+    }
+  }
+
+  private static void addEntry(JarOutputStream jos, String name) throws IOException {
+    ZipEntry ze = new ZipEntry(name);
+    ze.setTime(0);
+    jos.putNextEntry(ze);
+  }
+}

third_party/ijar/test/IjarTests.java

@@ -250,7 +250,7 @@ static Map<String, byte[]> readJar(String path) throws IOException {
       Enumeration<JarEntry> entries = jf.entries();
       while (entries.hasMoreElements()) {
         JarEntry je = entries.nextElement();
-        if (!je.getName().endsWith(".class")) {
+        if (!je.getName().endsWith(".class") && !je.getName().endsWith(".kotlin_module")) {
           continue;
         }
         classes.put(je.getName(), ByteStreams.toByteArray(jf.getInputStream(je)));
@@ -284,6 +284,15 @@ public void moduleInfo() throws Exception {
     assertThat(new String(lib.get("foo/module-info.class"), UTF_8)).isEqualTo("goodbye");
   }
 
+  @Test
+  public void kotlinModule() throws Exception {
+    Map<String, byte[]> lib = readJar("third_party/ijar/test/kotlin_module-interface.jar");
+    assertThat(lib.keySet())
+        .containsExactly("java/lang/String.class", "META-INF/bar.kotlin_module");
+    // ijar passes kotlin modules through unmodified
+    assertThat(new String(lib.get("META-INF/bar.kotlin_module"), UTF_8)).isEqualTo("hello");
+  }
+
   @Test
   public void testTargetLabel() throws Exception {
     try (JarFile jf =