libprocessgroup: Add support for task profiles

Abstract usage of cgroups into task profiles that allows for changes
in cgroup hierarchy and version without affecting framework codebase.
Rework current processgroup and sched_policy API function implementations
to use task profiles instead of hardcoded paths and attributes.
Mount cgroups using information from cgroups.json rather than from init.rc

Exempt-From-Owner-Approval: already approved in internal master

Bug: 111307099
Test: builds, boots

Change-Id: If5532d6dc570add825cebd5b5148e00c7d688e32
Merged-In: If5532d6dc570add825cebd5b5148e00c7d688e32
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
diff --git a/libprocessgroup/cgroup_map.h b/libprocessgroup/cgroup_map.h
new file mode 100644
index 0000000..ba2caf7
--- /dev/null
+++ b/libprocessgroup/cgroup_map.h
@@ -0,0 +1,96 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <sys/cdefs.h>
+#include <sys/types.h>
+
+#include <map>
+#include <mutex>
+#include <string>
+
+// Minimal controller description to be mmapped into process address space
+class CgroupController {
+  public:
+    CgroupController() {}
+    CgroupController(uint32_t version, const std::string& name, const std::string& path);
+
+    uint32_t version() const { return version_; }
+    const char* name() const { return name_; }
+    const char* path() const { return path_; }
+
+    std::string GetTasksFilePath(const std::string& path) const;
+    std::string GetProcsFilePath(const std::string& path, uid_t uid, pid_t pid) const;
+    bool GetTaskGroup(int tid, std::string* group) const;
+
+  private:
+    static constexpr size_t CGROUP_NAME_BUF_SZ = 16;
+    static constexpr size_t CGROUP_PATH_BUF_SZ = 32;
+
+    uint32_t version_;
+    char name_[CGROUP_NAME_BUF_SZ];
+    char path_[CGROUP_PATH_BUF_SZ];
+};
+
+// Complete controller description for mounting cgroups
+class CgroupDescriptor {
+  public:
+    CgroupDescriptor(uint32_t version, const std::string& name, const std::string& path,
+                     mode_t mode, const std::string& uid, const std::string& gid);
+
+    const CgroupController* controller() const { return &controller_; }
+    mode_t mode() const { return mode_; }
+    std::string uid() const { return uid_; }
+    std::string gid() const { return gid_; }
+
+  private:
+    CgroupController controller_;
+    mode_t mode_;
+    std::string uid_;
+    std::string gid_;
+};
+
+struct CgroupFile {
+    static constexpr uint32_t FILE_VERSION_1 = 1;
+    static constexpr uint32_t FILE_CURR_VERSION = FILE_VERSION_1;
+
+    uint32_t version_;
+    uint32_t controller_count_;
+    CgroupController controllers_[];
+};
+
+class CgroupMap {
+  public:
+    static constexpr const char* CGROUPS_RC_FILE = "cgroup.rc";
+
+    // Selinux policy ensures only init process can successfully use this function
+    static bool SetupCgroups();
+
+    static CgroupMap& GetInstance();
+
+    const CgroupController* FindController(const std::string& name) const;
+
+  private:
+    struct CgroupFile* cg_file_data_;
+    size_t cg_file_size_;
+
+    CgroupMap();
+    ~CgroupMap();
+
+    bool LoadRcFile();
+    void Print();
+};