libprocessgroup: Add libcgrouprc_format

This module defines the wire format of the mmap()ed cgroup.rc
file.

Test: builds
Bug: 123664216

Change-Id: Iaf6199f759a6264590b13ca7ba6d7f576c3ed56a
diff --git a/libprocessgroup/cgrouprc_format/Android.bp b/libprocessgroup/cgrouprc_format/Android.bp
new file mode 100644
index 0000000..dfbeed7
--- /dev/null
+++ b/libprocessgroup/cgrouprc_format/Android.bp
@@ -0,0 +1,32 @@
+// 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.
+
+cc_library_static {
+    name: "libcgrouprc_format",
+    host_supported: true,
+    recovery_available: true,
+    srcs: [
+        "cgroup_controller.cpp",
+    ],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
+    export_include_dirs: [
+        "include",
+    ],
+    shared_libs: [
+        "libbase",
+    ],
+}
diff --git a/libprocessgroup/cgrouprc_format/cgroup_controller.cpp b/libprocessgroup/cgrouprc_format/cgroup_controller.cpp
new file mode 100644
index 0000000..877eed8
--- /dev/null
+++ b/libprocessgroup/cgrouprc_format/cgroup_controller.cpp
@@ -0,0 +1,49 @@
+/*
+ * 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.
+ */
+
+#include <processgroup/format/cgroup_controller.h>
+
+namespace android {
+namespace cgrouprc {
+namespace format {
+
+CgroupController::CgroupController(uint32_t version, const std::string& name,
+                                   const std::string& path) {
+    // strlcpy isn't available on host. Although there is an implementation
+    // in licutils, libcutils itself depends on libcgrouprc_format, causing
+    // a circular dependency.
+    version_ = version;
+    strncpy(name_, name.c_str(), sizeof(name_) - 1);
+    name_[sizeof(name_) - 1] = '\0';
+    strncpy(path_, path.c_str(), sizeof(path_) - 1);
+    path_[sizeof(path_) - 1] = '\0';
+}
+
+uint32_t CgroupController::version() const {
+    return version_;
+}
+
+const char* CgroupController::name() const {
+    return name_;
+}
+
+const char* CgroupController::path() const {
+    return path_;
+}
+
+}  // namespace format
+}  // namespace cgrouprc
+}  // namespace android
diff --git a/libprocessgroup/cgrouprc_format/include/processgroup/format/cgroup_controller.h b/libprocessgroup/cgrouprc_format/include/processgroup/format/cgroup_controller.h
new file mode 100644
index 0000000..64c7532
--- /dev/null
+++ b/libprocessgroup/cgrouprc_format/include/processgroup/format/cgroup_controller.h
@@ -0,0 +1,47 @@
+/*
+ * 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 <stdint.h>
+#include <string>
+
+namespace android {
+namespace cgrouprc {
+namespace format {
+
+// Minimal controller description to be mmapped into process address space
+struct CgroupController {
+  public:
+    CgroupController() {}
+    CgroupController(uint32_t version, const std::string& name, const std::string& path);
+
+    uint32_t version() const;
+    const char* name() const;
+    const char* path() 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];
+};
+
+}  // namespace format
+}  // namespace cgrouprc
+}  // namespace android
diff --git a/libprocessgroup/cgrouprc_format/include/processgroup/format/cgroup_file.h b/libprocessgroup/cgrouprc_format/include/processgroup/format/cgroup_file.h
new file mode 100644
index 0000000..f1678a1
--- /dev/null
+++ b/libprocessgroup/cgrouprc_format/include/processgroup/format/cgroup_file.h
@@ -0,0 +1,36 @@
+/*
+ * 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 <processgroup/format/cgroup_controller.h>
+
+namespace android {
+namespace cgrouprc {
+namespace format {
+
+struct CgroupFile {
+    uint32_t version_;
+    uint32_t controller_count_;
+    CgroupController controllers_[];
+
+    static constexpr uint32_t FILE_VERSION_1 = 1;
+    static constexpr uint32_t FILE_CURR_VERSION = FILE_VERSION_1;
+};
+
+}  // namespace format
+}  // namespace cgrouprc
+}  // namespace android