c - 创建 FIFO 时出错

Question

我有以下代码，我正在使用该函数mkfifo创建一个 Fifo，但问题是当我运行程序时，我得到 printf 说“创建 fifo 时出错”。会是什么呢？这是代码：

//gcc Exam.c -o p
//./p 5 /home/directoryFile.c

#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <dirent.h>
#include <sys/wait.h>

int main(int argc, char *argv[])
{
    int studentId, children = 0, j, i, childNumber[15], fdFile, fdread, fdFifo, fdOpenFifo;
    float bytesToRead;
    char directory[50];
    char *buffer = malloc(256), *textToSend = malloc(256), *buffer2 = malloc(256);
    char childFifo[16];

    system("clear");

    if(argc-1 < 1)
    {
        printf("\nSome arguments are missing\n");
        return EXIT_FAILURE;
    }

    studentId = atoi(argv[1]);
    strcpy(directory,argv[2]);

    if((studentId%2) == 0)
    {
        children = 15;
    }
    else
    {
        if((studentId%3) == 0)
        {
            children = 10;
        }
        else
        {
            if((studentId%5) == 0)
            {
                children = 7;
            }
            else
            {
                printf("\nThe studentId is invalid \n");
                return EXIT_FAILURE;
            }
        }
    }

    struct stat fileInfo;
    stat(argv[2],&fileInfo);

    bytesToRead = fileInfo.st_size / children;

    printf("Children: %d\n",children);
    printf("File size: %lld\n",(long long int) fileInfo.st_size);
    printf("Bytes: %.2f\n",bytesToRead);

    fdFile = open(directory,O_RDONLY);

    if(fdFile == -1)
    {
        printf("\nError opening file\n");
        return EXIT_FAILURE;
    }

    for(i=0;i<children;i++)
    {
        sprintf(childFifo,"Child_%d",i);

        fdFifo = mkfifo(childFifo,0777);

        if(fdFifo == -1)
        {
            printf("\nError creating the fifo\n");
            return EXIT_FAILURE;
        }

        childNumber[i] = fork();

        if(childNumber[i] == -1)
        {
            printf("\nError creating the child\n");
            return EXIT_FAILURE;
        }

        if(childNumber[i] == 0)
        {
            fdOpenFifo = open(childFifo,O_WRONLY);

            if(fdOpenFifo == -1)
            {
                printf("\nError opening the fifo\n");
                return EXIT_FAILURE;
            }

            fdread = read(fdFile,buffer,bytesToRead);

            if(fdread == -1)
            {
                printf("\nError reading the file\n");
                return EXIT_FAILURE;
            }

            //printf("%s",buffer);
            //printf("\n\n------------------------\n\n");

            write(fdOpenFifo,&buffer,sizeof(char));

            //sprintf(textToSend,"%s%s",textToSend,buffer);

            return EXIT_SUCCESS;
        }
        else
        {
            sleep(1);
            read(fdOpenFifo,&buffer2,sizeof(char));
            printf("\nI show the content of the file: %s\n",buffer2);
            //waitpid(childNumber[i],NULL,WNOHANG);
            close(fdOpenFifo);
        }
    }

    //printf("\nI show the content of the file: %s\n",textToSend);

    close(fdFile);

    for(j=0;j<children;j++)
    {
        wait(NULL);
    }

    return EXIT_SUCCESS;
}

这是输出：./p 5 /home/directoryFile.c

Children: 7
File size: 267
Bytes: 38.00

Error creating the fifo