Export proguard specs from aar_import

**Background**
bazelbuild#3778

proguard specs from the `aar_import` rule do not get bubbled up to `android_binary`. In this PR, I wire up a `ProguardSpecProvider` from this rule that exports the `proguard.txt` within an AAR if it exists and any transitive proguard specs from the `exports` attribute.

**Changes**
* Add an `aar_embedded_proguard_extractor` script to extract `proguard.txt` from an AAR if it exists otherwise generate an empty proguard specs file
* In AarImport, wire up the proguard extractor action and export results through a `ProguardSpecProvider`.

Once this lands, the android rules would need to be bumped.

**Test Plan**
* Added tests for the extraction python script
* Added tests for the `aar_import` rule changes

Closes bazelbuild#12749.

PiperOrigin-RevId: 359667674

Author: benjaminRomano

src/main/java/com/google/devtools/build/lib/rules/android/AarImport.java

@@ -14,6 +14,7 @@
 package com.google.devtools.build.lib.rules.android;
 
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.actions.Action;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.actions.Artifact.SpecialArtifact;
@@ -45,6 +46,8 @@
 import com.google.devtools.build.lib.rules.java.JavaSourceInfoProvider;
 import com.google.devtools.build.lib.rules.java.JavaSourceJarsProvider;
 import com.google.devtools.build.lib.rules.java.JavaToolchainProvider;
+import com.google.devtools.build.lib.rules.java.ProguardLibrary;
+import com.google.devtools.build.lib.rules.java.ProguardSpecProvider;
 import com.google.devtools.build.lib.starlarkbuildapi.android.DataBindingV2ProviderApi;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import javax.annotation.Nullable;
@@ -61,6 +64,7 @@
 public class AarImport implements RuleConfiguredTargetFactory {
   private static final String ANDROID_MANIFEST = "AndroidManifest.xml";
   private static final String MERGED_JAR = "classes_and_libs_merged.jar";
+  private static final String PROGUARD_SPEC = "proguard.txt";
 
   private final JavaSemantics javaSemantics;
   private final AndroidSemantics androidSemantics;
@@ -239,6 +243,7 @@ public ConfiguredTarget create(RuleContext ruleContext)
         .setFilesToBuild(filesToBuild)
         .addProvider(RunfilesProvider.class, RunfilesProvider.EMPTY)
         .addNativeDeclaredProvider(dataBindingV2Provider)
+        .addNativeDeclaredProvider(new ProguardSpecProvider(extractProguardSpecs(ruleContext, aar)))
         .addNativeDeclaredProvider(
             new AndroidNativeLibsInfo(
                 AndroidCommon.collectTransitiveNativeLibs(ruleContext).add(nativeLibs).build()))
@@ -256,6 +261,46 @@ private static NestedSet<Artifact> getCompileTimeJarsFromCollection(
     return isDirect ? provider.getDirectCompileTimeJars() : provider.getTransitiveCompileTimeJars();
   }
 
+  /**
+   * Collect Proguard Specs from transitives and proguard.txt if it exists in the AAR file. In the
+   * case the proguard.txt file does exists, we need to extract it from the AAR file
+   */
+  private NestedSet<Artifact> extractProguardSpecs(RuleContext ruleContext, Artifact aar) {
+
+    NestedSet<Artifact> proguardSpecs =
+        new ProguardLibrary(ruleContext).collectProguardSpecs(ImmutableSet.of("deps", "exports"));
+
+    Artifact proguardSpecArtifact = createAarArtifact(ruleContext, PROGUARD_SPEC);
+
+    ruleContext.registerAction(
+        createAarEmbeddedProguardExtractorActions(ruleContext, aar, proguardSpecArtifact));
+
+    NestedSetBuilder<Artifact> builder = NestedSetBuilder.naiveLinkOrder();
+    return builder.addTransitive(proguardSpecs).add(proguardSpecArtifact).build();
+  }
+
+  /**
+   * Create action to extract embedded Proguard.txt from an AAR. If the file is not found, an empty
+   * file will be created
+   */
+  private static Action[] createAarEmbeddedProguardExtractorActions(
+      RuleContext ruleContext, Artifact aar, Artifact proguardSpecArtifact) {
+    return new SpawnAction.Builder()
+        .useDefaultShellEnvironment()
+        .setExecutable(
+            ruleContext.getExecutablePrerequisite(AarImportBaseRule.AAR_EMBEDDED_PROGUARD_EXTACTOR))
+        .setMnemonic("AarEmbeddedProguardExtractor")
+        .setProgressMessage("Extracting proguard.txt from %s", aar.getFilename())
+        .addInput(aar)
+        .addOutput(proguardSpecArtifact)
+        .addCommandLine(
+            CustomCommandLine.builder()
+                .addExecPath("--input_aar", aar)
+                .addExecPath("--output_proguard_file", proguardSpecArtifact)
+                .build())
+        .build(ruleContext);
+  }
+
   private NestedSet<Artifact> getBootclasspath(RuleContext ruleContext) {
     if (AndroidCommon.getAndroidConfig(ruleContext).desugarJava8()) {
       return NestedSetBuilder.<Artifact>stableOrder()

src/main/java/com/google/devtools/build/lib/rules/android/AarImportBaseRule.java

@@ -34,6 +34,7 @@
 public class AarImportBaseRule implements RuleDefinition {
 
   static final String AAR_EMBEDDED_JARS_EXTACTOR = "$aar_embedded_jars_extractor";
+  static final String AAR_EMBEDDED_PROGUARD_EXTACTOR = "$aar_embedded_proguard_extractor";
   static final String AAR_NATIVE_LIBS_ZIP_CREATOR = "$aar_native_libs_zip_creator";
   static final String AAR_RESOURCES_EXTRACTOR = "$aar_resources_extractor";
   static final String ZIPPER = "$zipper";
@@ -66,6 +67,11 @@ public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment env)
                 .cfg(HostTransition.createFactory())
                 .exec()
                 .value(env.getToolsLabel("//tools/android:aar_embedded_jars_extractor")))
+        .add(
+            attr(AAR_EMBEDDED_PROGUARD_EXTACTOR, LABEL)
+                .cfg(HostTransition.createFactory())
+                .exec()
+                .value(env.getToolsLabel("//tools/android:aar_embedded_proguard_extractor")))
         .add(
             attr(AAR_NATIVE_LIBS_ZIP_CREATOR, LABEL)
                 .cfg(HostTransition.createFactory())

src/test/java/com/google/devtools/build/lib/analysis/mock/BazelAnalysisMock.java

@@ -448,6 +448,7 @@ private ImmutableList<String> createAndroidBuildContents() {
         .add("            jars = [ 'ZipFilterAction_deploy.jar' ])")
         .add("sh_binary(name = 'aar_resources_extractor', srcs = ['empty.sh'])")
         .add("sh_binary(name = 'aar_embedded_jars_extractor', srcs = ['empty.sh'])")
+        .add("sh_binary(name = 'aar_embedded_proguard_extractor', srcs = ['empty.sh'])")
         .add("java_import(name = 'idlclass_import',")
         .add("            jars = [ 'idlclass.jar' ])")
         .add("exports_files(['adb', 'adb_static'])")

src/test/java/com/google/devtools/build/lib/rules/android/AarImportTest.java

@@ -41,6 +41,7 @@
 import com.google.devtools.build.lib.rules.java.JavaRuleOutputJarsProvider.OutputJar;
 import com.google.devtools.build.lib.rules.java.JavaSourceInfoProvider;
 import com.google.devtools.build.lib.rules.java.JavaSourceJarsProvider;
+import com.google.devtools.build.lib.rules.java.ProguardSpecProvider;
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.List;
@@ -156,6 +157,46 @@ public void setup() throws Exception {
     getAnalysisMock().ccSupport().setupCcToolchainConfigForCpu(mockToolsConfig, "armeabi-v7a");
   }
 
+  @Test
+  public void proguardSpecsProvided() throws Exception {
+    ConfiguredTarget binaryTarget = getConfiguredTarget("//a:bar");
+
+    NestedSet<Artifact> transitiveProguardSpecs =
+        binaryTarget.get(ProguardSpecProvider.PROVIDER).getTransitiveProguardSpecs();
+
+    assertThat(
+            transitiveProguardSpecs.toSet().stream()
+                .map(Artifact::getRootRelativePathString)
+                .collect(Collectors.toSet()))
+        .containsExactly(
+            "a/_aar/bar/proguard.txt", "a/_aar/foo/proguard.txt", "a/_aar/baz/proguard.txt");
+  }
+
+  @Test
+  public void testProguardExtractor() throws Exception {
+    Artifact proguardSpecsAritfact =
+        getConfiguredTarget("//a:bar")
+            .get(ProguardSpecProvider.PROVIDER)
+            .getTransitiveProguardSpecs()
+            .toList()
+            .get(0);
+
+    Artifact aarProguardExtractor =
+        getHostConfiguredTarget(
+                ruleClassProvider.getToolsRepository()
+                    + "//tools/android:aar_embedded_proguard_extractor")
+            .getProvider(FilesToRunProvider.class)
+            .getExecutable();
+
+    assertThat(getGeneratingSpawnAction(proguardSpecsAritfact).getArguments())
+        .containsExactly(
+            aarProguardExtractor.getExecPathString(),
+            "--input_aar",
+            "a/bar.aar",
+            "--output_proguard_file",
+            proguardSpecsAritfact.getExecPathString());
+  }
+
   @Test
   public void aapt2RTxtProvided() throws Exception {
     useConfiguration("--android_sdk=//aapt2/sdk:sdk");

src/test/java/com/google/devtools/build/lib/rules/android/BUILD

@@ -26,6 +26,7 @@ java_test(
         "//src/main/java/com/google/devtools/build/lib/collect/nestedset",
         "//src/main/java/com/google/devtools/build/lib/rules/android",
         "//src/main/java/com/google/devtools/build/lib/rules/java:java-compilation",
+        "//src/main/java/com/google/devtools/build/lib/rules/java:java-rules",
         "//src/test/java/com/google/devtools/build/lib/actions/util",
         "//src/test/java/com/google/devtools/build/lib/analysis/util",
         "//third_party:guava",

tools/android/BUILD

@@ -118,6 +118,21 @@ py_test(
     ],
 )
 
+py_binary(
+    name = "aar_embedded_proguard_extractor",
+    srcs = ["aar_embedded_proguard_extractor.py"],
+    deps = [
+        ":junction_lib",
+        "//third_party/py/abseil",
+    ],
+)
+
+py_test(
+    name = "aar_embedded_proguard_extractor_test",
+    srcs = ["aar_embedded_proguard_extractor_test.py"],
+    deps = [":aar_embedded_proguard_extractor"],
+)
+
 py_binary(
     name = "aar_embedded_jars_extractor",
     srcs = ["aar_embedded_jars_extractor.py"],

tools/android/BUILD.tools

@@ -328,6 +328,16 @@ py_binary(
     ],
 )
 
+py_binary(
+    name = "aar_embedded_proguard_extractor",
+    srcs = ["aar_embedded_proguard_extractor.py"],
+    python_version = "PY3",
+    deps = [
+        ":junction_lib",
+        "//third_party/py/abseil",
+    ],
+)
+
 py_binary(
     name = "aar_embedded_jars_extractor",
     srcs = ["aar_embedded_jars_extractor.py"],

tools/android/aar_embedded_proguard_extractor.py

@@ -0,0 +1,76 @@
+# Lint as: python2, python3
+# pylint: disable=g-direct-third-party-import
+# Copyright 2021 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.
+"""A tool for extracting the proguard spec file from an AAR."""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import os
+import sys
+import zipfile
+
+# Do not edit this line. Copybara replaces it with PY2 migration helper.
+from absl import app
+from absl import flags
+
+from tools.android import junction
+
+FLAGS = flags.FLAGS
+
+flags.DEFINE_string("input_aar", None, "Input AAR")
+flags.mark_flag_as_required("input_aar")
+flags.DEFINE_string("output_proguard_file", None,
+                    "Output parameter file for proguard")
+flags.mark_flag_as_required("output_proguard_file")
+
+
+# Attempt to extract proguard spec from AAR. If the file doesn't exist, an empty
+# proguard spec file will be created
+def ExtractEmbeddedProguard(aar, output):
+  proguard_spec = "proguard.txt"
+
+  if proguard_spec in aar.namelist():
+    output.write(aar.read(proguard_spec))
+
+
+def _Main(input_aar, output_proguard_file):
+  with zipfile.ZipFile(input_aar, "r") as aar:
+    with open(output_proguard_file, "wb") as output:
+      ExtractEmbeddedProguard(aar, output)
+
+
+def main(unused_argv):
+  if os.name == "nt":
+    # Shorten paths unconditionally, because the extracted paths in
+    # ExtractEmbeddedJars (which we cannot yet predict, because they depend on
+    # the names of the Zip entries) may be longer than MAX_PATH.
+    aar_long = os.path.abspath(FLAGS.input_aar)
+    proguard_long = os.path.abspath(FLAGS.output_proguard_file)
+
+    with junction.TempJunction(os.path.dirname(aar_long)) as aar_junc:
+      with junction.TempJunction(
+          os.path.dirname(proguard_long)) as proguard_junc:
+        _Main(
+            os.path.join(aar_junc, os.path.basename(aar_long)),
+            os.path.join(proguard_junc, os.path.basename(proguard_long)))
+  else:
+    _Main(FLAGS.input_aar, FLAGS.output_proguard_file)
+
+
+if __name__ == "__main__":
+  FLAGS(sys.argv)
+  app.run(main)

tools/android/aar_embedded_proguard_extractor_test.py

@@ -0,0 +1,54 @@
+# Copyright 2021 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.
+"""Tests for aar_embedded_proguard_extractor."""
+
+import io
+import os
+import unittest
+import zipfile
+
+from tools.android import aar_embedded_proguard_extractor
+
+
+class AarEmbeddedProguardExtractor(unittest.TestCase):
+  """Unit tests for aar_embedded_proguard_extractor.py."""
+
+  # Python 2 alias
+  if not hasattr(unittest.TestCase, "assertCountEqual"):
+
+    def assertCountEqual(self, *args):
+      return self.assertItemsEqual(*args)
+
+  def setUp(self):
+    super(AarEmbeddedProguardExtractor, self).setUp()
+    os.chdir(os.environ["TEST_TMPDIR"])
+
+  def testNoProguardTxt(self):
+    aar = zipfile.ZipFile(io.BytesIO(), "w")
+    proguard_file = io.BytesIO()
+    aar_embedded_proguard_extractor.ExtractEmbeddedProguard(aar, proguard_file)
+    proguard_file.seek(0)
+    self.assertEqual(b"", proguard_file.read())
+
+  def testWithProguardTxt(self):
+    aar = zipfile.ZipFile(io.BytesIO(), "w")
+    aar.writestr("proguard.txt", "hello world")
+    proguard_file = io.BytesIO()
+    aar_embedded_proguard_extractor.ExtractEmbeddedProguard(aar, proguard_file)
+    proguard_file.seek(0)
+    self.assertEqual(b"hello world", proguard_file.read())
+
+
+if __name__ == "__main__":
+  unittest.main()