Add libapexutil static library

This provides a helper function to get active APEX packages by scanning
/apex directory. Even though this feature is already provided by
ApexService::getActivePackages(), but some processes (e.g.
linkerconfig) which can't rely on IPC may use this library.

Bug: 144659031
Test: atest --host libapexutil_tests
Change-Id: I92c69637e0599c1db05a323aaabb4c30ca135f8f

1 files changed, 102 insertions, 0 deletions

diff --git a/libs/libapexutil/apexutil_test.cpp b/libs/libapexutil/apexutil_test.cpp
new file mode 100644
index 0000000..1fd12f3
--- /dev/null
+++ b/libs/libapexutil/apexutil_test.cpp
@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#include "apexutil.h"
+
+#include <unistd.h>
+
+#include <string>
+#include <utility>
+#include <vector>
+
+#include <android-base/file.h>
+#include <apex_manifest.pb.h>
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+using namespace std::literals;
+
+using ::android::apex::GetActivePackages;
+using ::android::base::WriteStringToFile;
+using ::apex::proto::ApexManifest;
+using ::testing::Contains;
+using ::testing::Pair;
+using ::testing::UnorderedElementsAre;
+
+namespace {
+
+ApexManifest CreateApexManifest(std::string apex_name, int version) {
+  ApexManifest manifest;
+  manifest.set_name(apex_name);
+  manifest.set_version(version);
+  return manifest;
+}
+
+void Mkdir(std::string dir_path) {
+  if (access(dir_path.c_str(), F_OK) == 0)
+    return;
+  ASSERT_NE(-1, mkdir(dir_path.c_str(), 0755) == -1)
+      << "Failed to create a directory: " << dir_path;
+}
+
+void WriteFile(std::string file_path, std::string content) {
+  ASSERT_TRUE(WriteStringToFile(content, file_path))
+      << "Failed to write a file: " << file_path;
+}
+
+} // namespace
+
+namespace apex {
+namespace proto {
+
+// simple implementation for testing purpose
+bool operator==(const ApexManifest &lhs, const ApexManifest &rhs) {
+  return lhs.SerializeAsString() == rhs.SerializeAsString();
+}
+
+} // namespace proto
+} // namespace apex
+
+TEST(ApexUtil, GetActivePackages) {
+  TemporaryDir td;
+
+  // com.android.foo: valid
+  auto foo_path = td.path + "/com.android.foo"s;
+  auto foo_manifest = CreateApexManifest("com.android.foo", 1);
+  Mkdir(foo_path);
+  WriteFile(foo_path + "/apex_manifest.pb", foo_manifest.SerializeAsString());
+
+  // com.android.foo@1: ignore versioned
+  Mkdir(foo_path + "@1");
+  WriteFile(foo_path + "@1/apex_manifest.pb", foo_manifest.SerializeAsString());
+
+  // com.android.baz: valid
+  auto bar_path = td.path + "/com.android.bar"s;
+  auto bar_manifest = CreateApexManifest("com.android.bar", 2);
+  Mkdir(bar_path);
+  WriteFile(bar_path + "/apex_manifest.pb", bar_manifest.SerializeAsString());
+
+  // invalid: a directory without apex_manifest.pb
+  Mkdir(td.path + "/com.android.baz"s);
+  // invalid: a file
+  WriteFile(td.path + "/com.android.qux.apex"s, "");
+
+  auto apexes = GetActivePackages(td.path);
+  ASSERT_EQ(2U, apexes.size());
+
+  ASSERT_THAT(apexes, UnorderedElementsAre(Pair(foo_path, foo_manifest),
+                                           Pair(bar_path, bar_manifest)));
+}
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