107 lines
3.3 KiB
C++
107 lines
3.3 KiB
C++
/*
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* Copyright (C) 2019 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <memory>
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#include <android-base/logging.h>
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#include <android-base/stringprintf.h>
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#include <android-base/unique_fd.h>
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#include <android/cgrouprc.h>
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#include <processgroup/processgroup.h>
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#include "cgrouprc_internal.h"
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using android::base::StringPrintf;
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using android::base::unique_fd;
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using android::cgrouprc::format::CgroupController;
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using android::cgrouprc::format::CgroupFile;
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static CgroupFile* LoadRcFile() {
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struct stat sb;
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unique_fd fd(TEMP_FAILURE_RETRY(open(CGROUPS_RC_PATH, O_RDONLY | O_CLOEXEC)));
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if (fd < 0) {
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PLOG(ERROR) << "open() failed for " << CGROUPS_RC_PATH;
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return nullptr;
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}
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if (fstat(fd, &sb) < 0) {
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PLOG(ERROR) << "fstat() failed for " << CGROUPS_RC_PATH;
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return nullptr;
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}
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size_t file_size = sb.st_size;
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if (file_size < sizeof(CgroupFile)) {
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LOG(ERROR) << "Invalid file format " << CGROUPS_RC_PATH;
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return nullptr;
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}
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CgroupFile* file_data = (CgroupFile*)mmap(nullptr, file_size, PROT_READ, MAP_SHARED, fd, 0);
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if (file_data == MAP_FAILED) {
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PLOG(ERROR) << "Failed to mmap " << CGROUPS_RC_PATH;
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return nullptr;
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}
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if (file_data->version_ != CgroupFile::FILE_CURR_VERSION) {
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LOG(ERROR) << CGROUPS_RC_PATH << " file version mismatch";
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munmap(file_data, file_size);
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return nullptr;
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}
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auto expected = sizeof(CgroupFile) + file_data->controller_count_ * sizeof(CgroupController);
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if (file_size != expected) {
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LOG(ERROR) << CGROUPS_RC_PATH << " file has invalid size, expected " << expected
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<< ", actual " << file_size;
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munmap(file_data, file_size);
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return nullptr;
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}
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return file_data;
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}
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static CgroupFile* GetInstance() {
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// Deliberately leak this object (not munmap) to avoid a race between destruction on
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// process exit and concurrent access from another thread.
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static auto* file = LoadRcFile();
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return file;
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}
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uint32_t ACgroupFile_getVersion() {
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auto file = GetInstance();
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if (file == nullptr) return 0;
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return file->version_;
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}
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uint32_t ACgroupFile_getControllerCount() {
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auto file = GetInstance();
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if (file == nullptr) return 0;
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return file->controller_count_;
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}
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const ACgroupController* ACgroupFile_getController(uint32_t index) {
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auto file = GetInstance();
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if (file == nullptr) return nullptr;
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CHECK(index < file->controller_count_);
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// Although the object is not actually an ACgroupController object, all ACgroupController_*
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// functions implicitly convert ACgroupController* back to CgroupController* before invoking
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// member functions.
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return static_cast<ACgroupController*>(&file->controllers_[index]);
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}
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