1 files changed, 79 insertions, 0 deletions
diff --git a/apex/sdkextensions/derive_sdk/derive_sdk.cpp b/apex/sdkextensions/derive_sdk/derive_sdk.cpp
new file mode 100644
index 000000000000..6fb7ef43416e
--- /dev/null
+++ b/apex/sdkextensions/derive_sdk/derive_sdk.cpp
@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+#define LOG_TAG "derive_sdk"
+
+#include <algorithm>
+#include <dirent.h>
+#include <iostream>
+#include <sys/stat.h>
+#include <vector>
+
+#include <android-base/file.h>
+#include <android-base/logging.h>
+#include <android-base/properties.h>
+
+#include "frameworks/base/apex/sdkextensions/derive_sdk/sdk.pb.h"
+
+using com::android::sdkext::proto::SdkVersion;
+
+int main(int, char**) {
+    std::unique_ptr<DIR, decltype(&closedir)> apex(opendir("/apex"), closedir);
+    if (!apex) {
+        LOG(ERROR) << "Could not read /apex";
+        return EXIT_FAILURE;
+    }
+    struct dirent* de;
+    std::vector<std::string> paths;
+    while ((de = readdir(apex.get()))) {
+        std::string name = de->d_name;
+        if (name[0] == '.' || name.find('@') != std::string::npos) {
+            // Skip <name>@<ver> dirs, as they are bind-mounted to <name>
+            continue;
+        }
+        std::string path = "/apex/" + name + "/etc/sdkinfo.binarypb";
+        struct stat statbuf;
+        if (stat(path.c_str(), &statbuf) == 0) {
+            paths.push_back(path);
+        }
+    }
+
+    std::vector<int> versions;
+    for (const auto& path : paths) {
+        std::string contents;
+        if (!android::base::ReadFileToString(path, &contents, true)) {
+            LOG(ERROR) << "failed to read " << path;
+            continue;
+        }
+        SdkVersion sdk_version;
+        if (!sdk_version.ParseFromString(contents)) {
+            LOG(ERROR) << "failed to parse " << path;
+            continue;
+        }
+        LOG(INFO) << "Read version " << sdk_version.version() << " from " << path;
+        versions.push_back(sdk_version.version());
+    }
+    auto itr = std::min_element(versions.begin(), versions.end());
+    std::string prop_value = itr == versions.end() ? "0" : std::to_string(*itr);
+
+    if (!android::base::SetProperty("ro.build.version.extensions.r", prop_value)) {
+        LOG(ERROR) << "failed to set sdk_info prop";
+        return EXIT_FAILURE;
+    }
+
+    LOG(INFO) << "R extension version is " << prop_value;
+    return EXIT_SUCCESS;
+}