97 lines
3.0 KiB
C++
97 lines
3.0 KiB
C++
//
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// Copyright (C) 2020 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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#include "host/libs/msg_queue/msg_queue.h"
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/ipc.h>
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#include <sys/msg.h>
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#include <fstream>
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#include <iostream>
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#include <memory>
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#include <android-base/logging.h>
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namespace cuttlefish {
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// class holds `msgid` returned from msg_queue_create, and match the lifetime of
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// the message queue to the lifetime of the object.
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SysVMessageQueue::SysVMessageQueue(int id) { msgid = id; }
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SysVMessageQueue::~SysVMessageQueue(void) {
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if (msgctl(msgid, IPC_RMID, NULL) < 0) {
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int error_num = errno;
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LOG(ERROR) << "Could not remove message queue: " << strerror(error_num);
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}
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}
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// SysVMessageQueue::Create would return an empty/null std::unique_ptr if
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// initialization failed.
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std::unique_ptr<SysVMessageQueue> SysVMessageQueue::Create(
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const std::string& path, char proj_id) {
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// key file must exist before calling ftok
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std::fstream fs;
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fs.open(path, std::ios::out);
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fs.close();
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// only the owning user has access
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key_t key = ftok(path.c_str(), proj_id);
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if (key < 0) {
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int error_num = errno;
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LOG(ERROR) << "Could not ftok to create IPC key: " << strerror(error_num);
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return NULL;
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}
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int queue_id = msgget(key, 0);
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if (queue_id < 0) {
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queue_id = msgget(key, IPC_CREAT | IPC_EXCL | 0600);
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}
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auto msg = std::unique_ptr<SysVMessageQueue>(new SysVMessageQueue(queue_id));
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return msg;
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}
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int SysVMessageQueue::Send(void* data, size_t size, bool block) {
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int msgflg = block ? 0 : IPC_NOWAIT;
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if (msgsnd(msgid, data, size, msgflg) < 0) {
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int error_num = errno;
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if (error_num == EAGAIN) {
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// returns EAGAIN if queue is full and non-blocking
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return EAGAIN;
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}
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LOG(ERROR) << "Could not send message: " << strerror(error_num);
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return error_num;
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}
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return 0;
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}
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// If msgtyp is 0, then the first message in the queue is read.
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// If msgtyp is greater than 0, then the first message in the queue of type
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// msgtyp is read.
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// If msgtyp is less than 0, then the first message in the queue with the lowest
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// type less than or equal to the absolute value of msgtyp will be read.
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ssize_t SysVMessageQueue::Receive(void* data, size_t size, long msgtyp,
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bool block) {
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// System call fails with errno set to ENOMSG if queue is empty and
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// non-blocking.
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int msgflg = block ? 0 : IPC_NOWAIT;
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return msgrcv(msgid, data, size, msgtyp, msgflg);
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}
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} // namespace cuttlefish
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