Revert "libprocessgroup: Remove cgroup.rc file"

Revert submission 3212512

Reason for revert: Droidmonitor created revert due to b/372273614. Will be verifying through ABTD before submission.

Reverted changes: /q/submissionid:3212512

Change-Id: I37568516e973cb940f1229d52f94b8dc801da2ab
diff --git a/libprocessgroup/util/util.cpp b/libprocessgroup/util/util.cpp
index bff4c6f..9b88a22 100644
--- a/libprocessgroup/util/util.cpp
+++ b/libprocessgroup/util/util.cpp
@@ -18,33 +18,9 @@
 
 #include <algorithm>
 #include <iterator>
-#include <optional>
-#include <string_view>
-
-#include <mntent.h>
-
-#include <android-base/file.h>
-#include <android-base/logging.h>
-#include <android-base/properties.h>
-#include <android-base/stringprintf.h>
-#include <json/reader.h>
-#include <json/value.h>
-
-#include "../build_flags.h"
-#include "../internal.h"
-
-using android::base::GetUintProperty;
 
 namespace {
 
-constexpr const char* CGROUPS_DESC_FILE = "/etc/cgroups.json";
-constexpr const char* CGROUPS_DESC_VENDOR_FILE = "/vendor/etc/cgroups.json";
-constexpr const char* TEMPLATE_CGROUPS_DESC_API_FILE = "/etc/task_profiles/cgroups_%u.json";
-
-// This should match the publicly declared value in processgroup.h,
-// but we don't want this library to depend on libprocessgroup.
-constexpr std::string CGROUPV2_HIERARCHY_NAME_INTERNAL = "cgroup2";
-
 const char SEP = '/';
 
 std::string DeduplicateAndTrimSeparators(const std::string& path) {
@@ -66,135 +42,9 @@
     return ret;
 }
 
-void MergeCgroupToDescriptors(CgroupDescriptorMap* descriptors, const Json::Value& cgroup,
-                              const std::string& name, const std::string& root_path,
-                              int cgroups_version) {
-    const std::string cgroup_path = cgroup["Path"].asString();
-    std::string path;
-
-    if (!root_path.empty()) {
-        path = root_path;
-        if (cgroup_path != ".") {
-            path += "/";
-            path += cgroup_path;
-        }
-    } else {
-        path = cgroup_path;
-    }
-
-    uint32_t controller_flags = 0;
-
-    if (cgroup["NeedsActivation"].isBool() && cgroup["NeedsActivation"].asBool()) {
-        controller_flags |= CGROUPRC_CONTROLLER_FLAG_NEEDS_ACTIVATION;
-    }
-
-    if (cgroup["Optional"].isBool() && cgroup["Optional"].asBool()) {
-        controller_flags |= CGROUPRC_CONTROLLER_FLAG_OPTIONAL;
-    }
-
-    uint32_t max_activation_depth = UINT32_MAX;
-    if (cgroup.isMember("MaxActivationDepth")) {
-        max_activation_depth = cgroup["MaxActivationDepth"].asUInt();
-    }
-
-    CgroupDescriptor descriptor(
-            cgroups_version, name, path, std::strtoul(cgroup["Mode"].asString().c_str(), 0, 8),
-            cgroup["UID"].asString(), cgroup["GID"].asString(), controller_flags,
-            max_activation_depth);
-
-    auto iter = descriptors->find(name);
-    if (iter == descriptors->end()) {
-        descriptors->emplace(name, descriptor);
-    } else {
-        iter->second = descriptor;
-    }
-}
-
-bool ReadDescriptorsFromFile(const std::string& file_name, CgroupDescriptorMap* descriptors) {
-    static constexpr bool force_memcg_v2 = android::libprocessgroup_flags::force_memcg_v2();
-    std::vector<CgroupDescriptor> result;
-    std::string json_doc;
-
-    if (!android::base::ReadFileToString(file_name, &json_doc)) {
-        PLOG(ERROR) << "Failed to read task profiles from " << file_name;
-        return false;
-    }
-
-    Json::CharReaderBuilder builder;
-    std::unique_ptr<Json::CharReader> reader(builder.newCharReader());
-    Json::Value root;
-    std::string errorMessage;
-    if (!reader->parse(&*json_doc.begin(), &*json_doc.end(), &root, &errorMessage)) {
-        LOG(ERROR) << "Failed to parse cgroups description: " << errorMessage;
-        return false;
-    }
-
-    if (root.isMember("Cgroups")) {
-        const Json::Value& cgroups = root["Cgroups"];
-        for (Json::Value::ArrayIndex i = 0; i < cgroups.size(); ++i) {
-            std::string name = cgroups[i]["Controller"].asString();
-
-            if (force_memcg_v2 && name == "memory") continue;
-
-            MergeCgroupToDescriptors(descriptors, cgroups[i], name, "", 1);
-        }
-    }
-
-    bool memcgv2_present = false;
-    std::string root_path;
-    if (root.isMember("Cgroups2")) {
-        const Json::Value& cgroups2 = root["Cgroups2"];
-        root_path = cgroups2["Path"].asString();
-        MergeCgroupToDescriptors(descriptors, cgroups2, CGROUPV2_HIERARCHY_NAME_INTERNAL, "", 2);
-
-        const Json::Value& childGroups = cgroups2["Controllers"];
-        for (Json::Value::ArrayIndex i = 0; i < childGroups.size(); ++i) {
-            std::string name = childGroups[i]["Controller"].asString();
-
-            if (force_memcg_v2 && name == "memory") memcgv2_present = true;
-
-            MergeCgroupToDescriptors(descriptors, childGroups[i], name, root_path, 2);
-        }
-    }
-
-    if (force_memcg_v2 && !memcgv2_present) {
-        LOG(INFO) << "Forcing memcg to v2 hierarchy";
-        Json::Value memcgv2;
-        memcgv2["Controller"] = "memory";
-        memcgv2["NeedsActivation"] = true;
-        memcgv2["Path"] = ".";
-        memcgv2["Optional"] = true;  // In case of cgroup_disabled=memory, so we can still boot
-        MergeCgroupToDescriptors(descriptors, memcgv2, "memory",
-                                 root_path.empty() ? CGROUP_V2_ROOT_DEFAULT : root_path, 2);
-    }
-
-    return true;
-}
-
-using MountDir = std::string;
-using MountOpts = std::string;
-static std::optional<std::map<MountDir, MountOpts>> ReadCgroupV1Mounts() {
-    FILE* fp = setmntent("/proc/mounts", "r");
-    if (fp == nullptr) {
-        PLOG(ERROR) << "Failed to read mounts";
-        return std::nullopt;
-    }
-
-    std::map<MountDir, MountOpts> mounts;
-    const std::string_view CGROUP_V1_TYPE = "cgroup";
-    for (mntent* mentry = getmntent(fp); mentry != nullptr; mentry = getmntent(fp)) {
-        if (mentry->mnt_type && CGROUP_V1_TYPE == mentry->mnt_type &&
-            mentry->mnt_dir && mentry->mnt_opts) {
-            mounts[mentry->mnt_dir] = mentry->mnt_opts;
-        }
-    }
-    endmntent(fp);
-
-    return mounts;
-}
-
 }  // anonymous namespace
 
+namespace util {
 
 unsigned int GetCgroupDepth(const std::string& controller_root, const std::string& cgroup_path) {
     const std::string deduped_root = DeduplicateAndTrimSeparators(controller_root);
@@ -206,47 +56,4 @@
     return std::count(deduped_path.begin() + deduped_root.size(), deduped_path.end(), SEP);
 }
 
-bool ReadDescriptors(CgroupDescriptorMap* descriptors) {
-    // load system cgroup descriptors
-    if (!ReadDescriptorsFromFile(CGROUPS_DESC_FILE, descriptors)) {
-        return false;
-    }
-
-    // load API-level specific system cgroups descriptors if available
-    unsigned int api_level = GetUintProperty<unsigned int>("ro.product.first_api_level", 0);
-    if (api_level > 0) {
-        std::string api_cgroups_path =
-                android::base::StringPrintf(TEMPLATE_CGROUPS_DESC_API_FILE, api_level);
-        if (!access(api_cgroups_path.c_str(), F_OK) || errno != ENOENT) {
-            if (!ReadDescriptorsFromFile(api_cgroups_path, descriptors)) {
-                return false;
-            }
-        }
-    }
-
-    // load vendor cgroup descriptors if the file exists
-    if (!access(CGROUPS_DESC_VENDOR_FILE, F_OK) &&
-        !ReadDescriptorsFromFile(CGROUPS_DESC_VENDOR_FILE, descriptors)) {
-        return false;
-    }
-
-    // check for v1 mount/usability status
-    std::optional<std::map<MountDir, MountOpts>> v1Mounts;
-    for (auto& [name, descriptor] : *descriptors) {
-        const CgroupController* const controller = descriptor.controller();
-
-        if (controller->version() != 1) continue;
-
-        // Read only once, and only if we have at least one v1 controller
-        if (!v1Mounts) {
-            v1Mounts = ReadCgroupV1Mounts();
-            if (!v1Mounts) return false;
-        }
-
-        if (const auto it = v1Mounts->find(controller->path()); it != v1Mounts->end()) {
-            if (it->second.contains(controller->name())) descriptor.set_mounted(true);
-        }
-    }
-
-    return true;
-}
+}  // namespace util