Let ijar warn only once per unsupported attribute

third_party/ijar/classfile.cc

@@ -35,6 +35,7 @@
 #include <set>
 #include <sstream>
 #include <string>
+#include <unordered_set>
 #include <vector>
 
 #include "third_party/ijar/common.h"
@@ -112,10 +113,11 @@ enum TARGET_TYPE {
 struct Constant;
 
 // TODO(adonovan) these globals are unfortunate
-static std::vector<Constant*>        const_pool_in; // input constant pool
-static std::vector<Constant*>        const_pool_out; // output constant_pool
-static std::set<std::string>         used_class_names;
-static Constant *                    class_name;
+static std::vector<Constant*>          const_pool_in; // input constant pool
+static std::vector<Constant*>          const_pool_out; // output constant_pool
+static std::set<std::string>           used_class_names;
+static Constant *                      class_name;
+static std::unordered_set<std::string> unknown_attributes;
 
 // Returns the Constant object, given an index into the input constant pool.
 // Note: constant(0) == NULL; this invariant is exploited by the
@@ -1592,8 +1594,11 @@ void HasAttrs::ReadAttrs(const u1 *&p) {
       // not relevant for ijar.
       if (attr_name != "com.android.tools.r8.SynthesizedClass" &&
           attr_name != "com.android.tools.r8.SynthesizedClassV2") {
-        fprintf(stderr, "ijar: skipping unknown attribute: \"%s\".\n",
-                attr_name.c_str());
+        // Only warn about the first occurrence of each unknown attribute.
+        if (unknown_attributes.insert(attr_name).second) {
+          fprintf(stderr, "ijar: skipping unknown attribute: \"%s\".\n",
+                  attr_name.c_str());
+        }
       }
       p += attribute_length;
     }

third_party/ijar/test/BUILD

@@ -34,6 +34,7 @@ sh_test(
         "records/records.jar",
         "sealed/sealed.jar",
         ":source_debug_extension.jar",
+        ":duplicated_unsupported_attribute.jar",
         ":keep_for_compile_lib.jar",
         ":largest_regular.jar",
         ":smallest_zip64.jar",
@@ -210,6 +211,21 @@ genrule(
     tools = ["gen_source_debug_extension"],
 )
 
+java_binary(
+    name = "gen_duplicated_unsupported_attribute",
+    srcs = ["GenDuplicatedUnsupportedAttribute.java"],
+    main_class = "test.GenDuplicatedUnsupportedAttribute",
+    deps = ["//third_party:asm"],
+)
+
+genrule(
+    name = "gen_duplicated_unsupported_attribute_jar",
+    srcs = [],
+    outs = ["duplicated_unsupported_attribute.jar"],
+    cmd = "$(location :gen_duplicated_unsupported_attribute) $@",
+    tools = ["gen_duplicated_unsupported_attribute"],
+)
+
 java_binary(
     name = "gen_dynamic_constant",
     srcs = ["GenDynamicConstant.java"],

third_party/ijar/test/GenDuplicatedUnsupportedAttribute.java

@@ -0,0 +1,87 @@
+// Copyright 2024 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.
+
+package test;
+
+import org.objectweb.asm.Attribute;
+import org.objectweb.asm.ByteVector;
+import org.objectweb.asm.ClassWriter;
+import org.objectweb.asm.MethodVisitor;
+import org.objectweb.asm.Opcodes;
+
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.jar.JarOutputStream;
+import java.util.zip.ZipEntry;
+
+public class GenDuplicatedUnsupportedAttribute {
+  public static void main(String[] args) throws IOException {
+    try (JarOutputStream jos = new JarOutputStream(new FileOutputStream(args[0]))) {
+      jos.putNextEntry(new ZipEntry("unsupportedattributes/Test1.class"));
+      jos.write(dump("Test1"));
+      jos.putNextEntry(new ZipEntry("unsupportedattributes/Test2.class"));
+      jos.write(dump("Test2"));
+    }
+  }
+
+  public static byte[] dump(String name) {
+    ClassWriter cw = new ClassWriter(0);
+    MethodVisitor mv;
+
+    cw.visit(
+        52,
+        Opcodes.ACC_PUBLIC + Opcodes.ACC_SUPER,
+        "unsupportedattributes/" + name,
+        null,
+        "java/lang/Object",
+        null);
+
+    // This is the important part for the test - repeat an unsupported attribute.
+    cw.visitAttribute(new Attribute("some_unknown_type") {
+      @Override
+      protected ByteVector write(ClassWriter classWriter, byte[] code, int codeLength, int maxStack, int maxLocals) {
+        return new ByteVector().putInt(1234);
+      }
+    });
+
+    {
+      mv = cw.visitMethod(Opcodes.ACC_PUBLIC, "<init>", "()V", null, null);
+      mv.visitCode();
+      mv.visitVarInsn(Opcodes.ALOAD, 0);
+      mv.visitMethodInsn(Opcodes.INVOKESPECIAL, "java/lang/Object", "<init>", "()V", false);
+      mv.visitInsn(Opcodes.RETURN);
+      mv.visitMaxs(1, 1);
+      mv.visitEnd();
+    }
+    {
+      mv = cw.visitMethod(
+          Opcodes.ACC_PUBLIC + Opcodes.ACC_STATIC,
+          "main",
+          "([Ljava/lang/String;)V",
+          null,
+          null);
+      mv.visitCode();
+      mv.visitFieldInsn(Opcodes.GETSTATIC, "java/lang/System", "err", "Ljava/io/PrintStream;");
+      mv.visitLdcInsn("Hello");
+      mv.visitMethodInsn(
+          Opcodes.INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false);
+      mv.visitInsn(Opcodes.RETURN);
+      mv.visitMaxs(2, 1);
+      mv.visitEnd();
+    }
+    cw.visitEnd();
+
+    return cw.toByteArray();
+  }
+}

third_party/ijar/test/ijar_test.sh

@@ -81,6 +81,8 @@ SEALED_JAR=$IJAR_SRCDIR/test/sealed/sealed.jar
 SEALED_IJAR=$TEST_TMPDIR/sealed_interface.jar
 SOURCEDEBUGEXT_JAR=$IJAR_SRCDIR/test/source_debug_extension.jar
 SOURCEDEBUGEXT_IJAR=$TEST_TMPDIR/source_debug_extension.jar
+DUPLICATEDUNSUPPORTEDATTRIBUTE_JAR=$IJAR_SRCDIR/test/duplicated_unsupported_attribute.jar
+DUPLICATEDUNSUPPORTEDATTRIBUTE_IJAR=$TEST_TMPDIR/duplicated_unsupported_attribute.jar
 CENTRAL_DIR_LARGEST_REGULAR=$IJAR_SRCDIR/test/largest_regular.jar
 CENTRAL_DIR_SMALLEST_ZIP64=$IJAR_SRCDIR/test/smallest_zip64.jar
 CENTRAL_DIR_ZIP64=$IJAR_SRCDIR/test/definitely_zip64.jar
@@ -575,6 +577,12 @@ function test_source_debug_extension_attribute() {
   expect_not_log "SourceDebugExtension" "SourceDebugExtension preserved!"
 }
 
+function test_duplicated_unsupported_attribute() {
+  # Check that unsupported attribute warnings are only emitted once
+  $IJAR $DUPLICATEDUNSUPPORTEDATTRIBUTE_JAR $DUPLICATEDUNSUPPORTEDATTRIBUTE_IJAR >& $TEST_log || fail "ijar failed"
+  expect_log_once 'skipping unknown attribute: "some_unknown_type"'
+}
+
 function test_keep_for_compile() {
   $IJAR --strip_jar $KEEP_FOR_COMPILE $TEST_TMPDIR/keep.jar \
     || fail "ijar failed"