Add option to extract proguard configurations in jvm_import

.bazelrc

@@ -7,6 +7,8 @@ build --tool_java_runtime_version=remotejdk_11
 build --experimental_strict_java_deps=strict
 build --explicit_java_test_deps
 
+build --experimental_google_legacy_api
+
 # Make sure we get something helpful when tests fail
 test --verbose_failures
 test --test_output=errors

BUILD

@@ -70,6 +70,7 @@ bzl_library(
         "//private/rules:urls.bzl",
         "//private/rules:v1_lock_file.bzl",
         "//private/rules:v2_lock_file.bzl",
+        "//settings:extract_proguard_config.bzl",
         "//settings:stamp_manifest.bzl",
     ],
     visibility = [

examples/android_instrumentation_test/.bazelrc

@@ -65,3 +65,5 @@ build:rbe_demo --experimental_remote_download_outputs=toplevel
 build:rbe_demo --experimental_inmemory_dotd_files
 build:rbe_demo --experimental_inmemory_jdeps_files
 build:rbe_demo --jobs=300
+
+build --experimental_google_legacy_api # Needed to use ProguardSpecProvider

examples/android_kotlin_app/.bazelrc

@@ -0,0 +1 @@
+build --experimental_google_legacy_api # Needed to use ProguardSpecProvider

examples/android_local_test/.bazelrc

@@ -0,0 +1 @@
+build --experimental_google_legacy_api # Needed to use ProguardSpecProvider

examples/java-export/.bazelrc

@@ -3,3 +3,5 @@ build --java_runtime_version=remotejdk_11
 build --tool_java_language_version=11
 
 build --javacopt="--release 11"
+
+build --experimental_google_legacy_api # Needed to use ProguardSpecProvider

examples/kt_android_local_test/.bazelrc

@@ -0,0 +1 @@
+build --experimental_google_legacy_api # Needed to use ProguardSpecProvider

examples/pom_file_generation/.bazelrc

@@ -0,0 +1 @@
+build --experimental_google_legacy_api # Needed to use ProguardSpecProvider

examples/protobuf-java/.bazelrc

@@ -0,0 +1 @@
+build --experimental_google_legacy_api # Needed to use ProguardSpecProvider

examples/scala_akka/.bazelrc

@@ -0,0 +1 @@
+build --experimental_google_legacy_api # Needed to use ProguardSpecProvider

examples/simple/.bazelrc

@@ -0,0 +1 @@
+build --experimental_google_legacy_api # Needed to use ProguardSpecProvider

examples/spring_boot/.bazelrc

@@ -0,0 +1 @@
+build --experimental_google_legacy_api # Needed to use ProguardSpecProvider

private/rules/jvm_import.bzl

@@ -8,6 +8,7 @@
 # [1]: https://github.com/bazelbuild/bazel/issues/4549
 
 load("//settings:stamp_manifest.bzl", "StampManifestProvider")
+load("//settings:extract_proguard_config.bzl", "ExtractProguardConfigProvider")
 
 def _jvm_import_impl(ctx):
     if len(ctx.files.jars) != 1:
@@ -30,6 +31,26 @@ def _jvm_import_impl(ctx):
     else:
         outjar = injar
 
+    proguard_info = []
+    if ctx.attr._extract_proguard_config[ExtractProguardConfigProvider].extract_proguard_config:
+        spec = ctx.actions.declare_file("%s_proguard.pro" % injar.basename.split(".jar")[0])
+
+        args = ctx.actions.args()
+        args.add("--jar_to_spec", "%s:%s" % (injar.path, spec.path))
+
+        ctx.actions.run(
+            inputs = [injar],
+            outputs = [spec],
+            executable = ctx.executable._proguard_config_extractor,
+            arguments = [args],
+            mnemonic = "ExtractProguardSpec",
+            progress_message = "Extracting proguard config of %s" % ctx.label,
+        )
+
+        proguard_info = [
+            ProguardSpecProvider(depset(direct = [spec])),
+        ]
+
     compilejar = ctx.actions.declare_file("header_" + injar.basename, sibling = injar)
     args = ctx.actions.args()
     args.add_all(["--source", outjar, "--output", compilejar])
@@ -69,7 +90,7 @@ def _jvm_import_impl(ctx):
             ],
             neverlink = ctx.attr.neverlink,
         ),
-    ]
+    ] + proguard_info
 
 jvm_import = rule(
     attrs = {
@@ -95,9 +116,17 @@ jvm_import = rule(
             cfg = "exec",
             default = "//private/tools/java/com/github/bazelbuild/rules_jvm_external/jar:AddJarManifestEntry",
         ),
+        "_proguard_config_extractor": attr.label(
+            executable = True,
+            cfg = "exec",
+            default = "//private/tools/java/com/github/bazelbuild/rules_jvm_external/jar:ExtractProguardConfig",
+        ),
         "_stamp_manifest": attr.label(
             default = "@rules_jvm_external//settings:stamp_manifest",
         ),
+        "_extract_proguard_config": attr.label(
+            default = "@rules_jvm_external//settings:extract_proguard_config",
+        ),
     },
     implementation = _jvm_import_impl,
     provides = [JavaInfo],

private/tools/java/com/github/bazelbuild/rules_jvm_external/jar/BUILD

@@ -51,3 +51,14 @@ java_binary(
         "//private/tools/java/com/github/bazelbuild/rules_jvm_external/zip",
     ],
 )
+
+java_binary(
+    name = "ExtractProguardConfig",
+    srcs = [
+        "ExtractProguardConfig.java",
+    ],
+    main_class = "com.github.bazelbuild.rules_jvm_external.jar.ExtractProguardConfig",
+    visibility = [
+        "//visibility:public",
+    ],
+)

private/tools/java/com/github/bazelbuild/rules_jvm_external/jar/ExtractProguardConfig.java

@@ -0,0 +1,94 @@
+package com.github.bazelbuild.rules_jvm_external.jar;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Enumeration;
+import java.util.List;
+import java.util.jar.JarEntry;
+import java.util.jar.JarFile;
+
+public final class ExtractProguardConfig {
+
+    private List<String> jarToSpec;
+
+    // Directories to search for proguard configurations.
+    // The list is sorted from highest priorty to lowest priority
+    // Only the first one is extracted.
+    private List<String> proguardDirs = Arrays.asList(
+            "META-INF/com.android.tools/r8",
+            "META-INF/com.android.tools/proguard",
+            "META-INF/proguard"
+    );
+
+    public ExtractProguardConfig(List<String> jarToSpec) {
+        this.jarToSpec = jarToSpec;
+    }
+
+    private boolean maybeCopySpec(String jarPath, String directoryName, String spec) {
+        try {
+            JarFile jarFile = new JarFile(jarPath);
+            Enumeration<JarEntry> entries = jarFile.entries();
+            while (entries.hasMoreElements()) {
+                JarEntry entry = entries.nextElement();
+                if (!entry.isDirectory() && entry.getName().startsWith(directoryName)) {
+                    File outputFile = new File(spec);
+                    FileOutputStream outputStream = new FileOutputStream(outputFile);
+                    jarFile.getInputStream(entry).transferTo(outputStream);
+
+                    outputStream.close();
+                    return true;
+                }
+            }
+            jarFile.close();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+        return false;
+    }
+
+    private void extractSpec(String jar, String spec) {
+        boolean hadSpec = false;
+        for (String dir : proguardDirs) {
+            hadSpec = maybeCopySpec(jar, dir, spec);
+            if (hadSpec) {
+                break;
+            }
+        }
+
+        if (!hadSpec) {
+            try {
+                File file = new File(spec);
+                file.createNewFile();
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+
+    public void run() {
+        for (String js : jarToSpec) {
+            String[] parts = js.split(":");
+            if (parts.length != 2) {
+                throw new IllegalArgumentException("Invalid jar_to_spec value: " + js);
+            }
+            extractSpec(parts[0], parts[1]);
+        }
+    }
+
+    public static void main(String[] args) {
+        List<String> jarToSpec = new ArrayList();
+        for (int i = 0; i < args.length; i++) {
+            if (args[i].equals("--jar_to_spec")) {
+                if (i + 1 < args.length) {
+                    jarToSpec.add(args[i + 1]);
+                    i++; 
+                }
+            }
+        }
+
+        new ExtractProguardConfig(jarToSpec).run();
+    }
+}

settings/BUILD

@@ -1,12 +1,21 @@
 load("//settings:stamp_manifest.bzl", "stamp_manifest")
+load("//settings:extract_proguard_config.bzl", "extract_proguard_config")
 
 package(
     default_visibility = ["//visibility:public"],
 )
 
-exports_files(["stamp_manifest.bzl"])
+exports_files([
+    "extract_proguard_config.bzl",
+    "stamp_manifest.bzl",
+])
 
 stamp_manifest(
     name = "stamp_manifest",
     build_setting_default = True,
 )
+
+extract_proguard_config(
+    name = "extract_proguard_config",
+    build_setting_default = False,
+)

settings/extract_proguard_config.bzl

@@ -0,0 +1,9 @@
+ExtractProguardConfigProvider = provider(fields = ["extract_proguard_config"])
+
+def _impl(ctx):
+    return ExtractProguardConfigProvider(extract_proguard_config = ctx.build_setting_value)
+
+extract_proguard_config = rule(
+    implementation = _impl,
+    build_setting = config.bool(flag = True),
+)