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/*
* 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 <sys/mman.h>
#include <sys/stat.h>
#include <memory>
#include <android-base/logging.h>
#include <android-base/stringprintf.h>
#include <android-base/unique_fd.h>
#include <android/cgrouprc.h>
#include <processgroup/processgroup.h>
#include "cgrouprc_internal.h"
using android::base::StringPrintf;
using android::base::unique_fd;
using android::cgrouprc::format::CgroupController;
using android::cgrouprc::format::CgroupFile;
static CgroupFile* LoadRcFile() {
struct stat sb;
unique_fd fd(TEMP_FAILURE_RETRY(open(CGROUPS_RC_PATH, O_RDONLY | O_CLOEXEC)));
if (fd < 0) {
PLOG(ERROR) << "open() failed for " << CGROUPS_RC_PATH;
return nullptr;
}
if (fstat(fd, &sb) < 0) {
PLOG(ERROR) << "fstat() failed for " << CGROUPS_RC_PATH;
return nullptr;
}
size_t file_size = sb.st_size;
if (file_size < sizeof(CgroupFile)) {
LOG(ERROR) << "Invalid file format " << CGROUPS_RC_PATH;
return nullptr;
}
CgroupFile* file_data = (CgroupFile*)mmap(nullptr, file_size, PROT_READ, MAP_SHARED, fd, 0);
if (file_data == MAP_FAILED) {
PLOG(ERROR) << "Failed to mmap " << CGROUPS_RC_PATH;
return nullptr;
}
if (file_data->version_ != CgroupFile::FILE_CURR_VERSION) {
LOG(ERROR) << CGROUPS_RC_PATH << " file version mismatch";
munmap(file_data, file_size);
return nullptr;
}
auto expected = sizeof(CgroupFile) + file_data->controller_count_ * sizeof(CgroupController);
if (file_size != expected) {
LOG(ERROR) << CGROUPS_RC_PATH << " file has invalid size, expected " << expected
<< ", actual " << file_size;
munmap(file_data, file_size);
return nullptr;
}
return file_data;
}
static CgroupFile* GetInstance() {
// Deliberately leak this object (not munmap) to avoid a race between destruction on
// process exit and concurrent access from another thread.
static auto* file = LoadRcFile();
return file;
}
uint32_t ACgroupFile_getVersion() {
auto file = GetInstance();
if (file == nullptr) return 0;
return file->version_;
}
uint32_t ACgroupFile_getControllerCount() {
auto file = GetInstance();
if (file == nullptr) return 0;
return file->controller_count_;
}
const ACgroupController* ACgroupFile_getController(uint32_t index) {
auto file = GetInstance();
if (file == nullptr) return nullptr;
CHECK(index < file->controller_count_);
// Although the object is not actually an ACgroupController object, all ACgroupController_*
// functions implicitly convert ACgroupController* back to CgroupController* before invoking
// member functions.
return static_cast<ACgroupController*>(&file->controllers_[index]);
}
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