Export proguard specs from aar_import
**Background**
https://github.com/bazelbuild/bazel/issues/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 #12749.
PiperOrigin-RevId: 359667674
diff --git a/tools/android/aar_embedded_proguard_extractor.py b/tools/android/aar_embedded_proguard_extractor.py
new file mode 100644
index 0000000..f39e5e5
--- /dev/null
+++ b/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)
