c - 使用消息队列无法发送和接收消息

Question

我正在尝试从孩子向父母发送消息（它有 2 个孩子）。但是当我在 Xcode 中运行它时它返回错误“无效参数”，当我在 vim 中运行它时它只是挂起并且什么都不做。我想从第二个孩子向父母发送消息。

1. 我已经检查了这些，它们工作正常：
   • 父子id匹配
   • msgrcv和的论点msgsnd
   • 分叉和消息队列创建

（我添加了适当的标题）

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>

void signalHandler(int signumber,siginfo_t* info,void* nonused){
  printf("Signal with number %i has arrived\n",signumber);
  switch (info->si_code){
    case SI_USER:
          printf("Process (PID number %i) sent the signal \n",info->si_pid); break;
    case SI_QUEUE:
          printf("It was sent by a sigqueue, sending process (PID %i)\n",info->si_pid);

    default: printf("");
  }
}

struct messg {
    long mtype;
    char mtext[1024];
};

int sendMsg (int mqueue){
    const struct messg m = {5,"Test message"};
    int status;
    status = msgsnd(mqueue, &mqueue, strlen(m.mtext) + 1, IPC_NOWAIT);
    if (status < 0){
        perror("Message send error!");
    }

    return 0;
}

int receiveMsg(int mqueue){
    struct messg m;

    int status;
    status = msgrcv(mqueue, &m, 1024 - sizeof(long), 5, 0);

    if (status < 0){
        printf("Errno : %d\n",status);
        perror("Message recieve error!");
    } else {
        printf("Received msg : %s",m.mtext);
    }

    return 0;
}


int main(int argc, const char * argv[]) {


    struct sigaction sigact;
    sigact.sa_sigaction=signalHandler;
    sigemptyset(&sigact.sa_mask);
    sigact.sa_flags=SA_SIGINFO;
    sigaction(SIGTERM,&sigact,NULL);

    key_t key = ftok(argv[0],1);
    int messg = msgget(key, 0600 | IPC_CREAT);
    pid_t parent_co;
    int pid_co_parent[2];

    if (messg < 0){
        perror("Message creation error!");
        return 1;
    }


    pid_t child_nhp;
    int pid_child_nhp[2];

    char sz[250];


    if(pipe(pid_co_parent) == -1){
        perror("Pipe");
        exit(0);
    }

    if(pipe(pid_co_parent) == -1){
        perror("Pipe");
        exit(0);
    }

    parent_co = fork();

    if (parent_co == 0) {

        sleep(3);

        printf("(Police Lieutenant-colon) Child process : child_id : %d, parent_id : %d\n",getpid(),getppid());
        kill(getppid(), SIGTERM);

        read(pid_co_parent[0], sz, sizeof(sz));
        printf("(Communication Officer) : %s\n" ,sz);
        char answer[250];

        strcpy(answer, "Yes, it is compulsory to wear the mask when you leave your flat!");

        write(pid_co_parent[1], answer, strlen(answer) + 1);
        close(pid_co_parent[0]);

        return 0;

    } else {

        printf("(Communication Officer) Parent process_id : %d\n",getpid());
        pause();


        char ques[250];
        strcpy(ques, "Is it compulsory to wear a mask in the shops?");

        write(pid_co_parent[1], ques, strlen(ques) + 1);
        close(pid_co_parent[1]);

        read(pid_co_parent[0], sz, sizeof(sz));
        printf("(Police Lieutenant-colon) : %s\n",sz);
        close(pid_co_parent[0]);

        child_nhp = fork();

        if (child_nhp < 0){
            perror("fork error for child nhp!");
            exit(0);
        }

        if (child_nhp == 0) {
            printf("(National Head Physician)  child_id : %d, parent_id : %d\n",getpid(),getppid());
            receiveMsg(messg);
            return 0;
        } else {
            sendMsg(messg);
            wait(NULL);
            // parent process


        }


        fflush(NULL);
        wait(NULL);




    }

    return 0;
}

标签： clinuxpipemessage-queue