c-如何在多个管道中同时读写？

Question

this is just part of my program.

char temp[100];//stores the temporary value from the pipe read
if(close(fd[0][1])==-1){//closing the write of the first pipe
    perror("Error: closing the write pipe [child]-");
    exit(-1);
}
if(close(fd[1][0])==-1){//closing the read of the second pipe
    perror("Error: closing the write pipe [child]-");
    exit(-1);
}

if(!(read(fd[0][0],temp,10)>0)){//the first number read specifies the overall filter
    fprintf(stderr,"Error: while reading the filter");
    exit(-1);
}
filter=strtol(temp,NULL,10);//storing the first read as the filter
while(read(fd[0][0],temp,10)>0){//reading the rest of the data for filtering
    printf("[%d] child received %s\n",getpid(),temp);
    if(strtol(temp,NULL,10)%filter!=0){//checking to see if the read number is divisible by the filter
        //if not, we write it to the second pipe
        if(write(fd[1][1],temp,10)==-1){
            perror("Error: failed to write to pipe -");
            exit(-1);
        }
    }
}

if(close(fd[1][1])==-1){//closing the write of the second pipe
    perror("Error: closing the read pipe [child]-");
    exit(-1);
}
if(close(fd[0][0])==-1){//closing the read of the first pipe
    perror("Error: closing the read pipe [child]-");
    exit(-1);
}

so i wrote 10 separate numbers(converted to string) to fd[0][1] in my code in the parent process (i have not showed it here but i know that it works). Now, i can only read one data from fd[0][0] . if i remove

if(write(fd[1][1],temp,10)==-1){
    perror("Error: failed to write to pipe -");
    exit(-1);
}

it will read all of the data. Why is this interfering with the read?if there are any other improvements in my code that i can make, let me know.

here is the full code:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <math.h>
#include <sys/wait.h>

int main(int argc,char*argv[]){
/*---------------Error checking----------------*/
//checking to see if correct number of arguments is provided
if(argc!=2){
    fprintf(stderr, "Usage:\n\tpfact n\n");
    exit(1);
}

//checking to see if correct argument is provided
char *leftOver;
int checkNumber=strtol(argv[1],&leftOver,10);
int squareroot_checkNumber=sqrt((double)checkNumber);
if(leftOver[0]!='\0'){
    fprintf(stderr, "Usage:\n\tpfact n\n");
    exit(1);
}

if(checkNumber<=0){
    fprintf(stderr, "Usage:\n\tpfact n\n");
    exit(1);
}
/*-------------------------------------------*/
char factors[checkNumber-1][100];
int factor_size=0;
strcpy(factors[0],"-1");
int child;
int number_process=0;//keeps track of number of processes created
int isInitialized=0;//sees if we are initialized yet or not
int filter;//stores the number used to filter the data

int fd[2][2];

//create the two pipes
if(pipe(fd[0]) == -1){
    perror("Error: creating a pipe -");
}

if(pipe(fd[1]) == -1){
    perror("Error: creating a pipe -");
}
do{
    child=fork();
    if(child<0){
        perror("Error: making a child -");
        exit(1);
    }

    if(child>0){
        if(isInitialized==0){//not initialized yet //no data has been written to the pipe
            isInitialized=1;//it has been initilized now
            if(close(fd[0][0])==-1){//closing the read of the first pipe
                perror("Error: closing the read pipe [parent]-");
                exit(-1);
            }
            //writing 2 to m to the pipe
            for(int i=2;i<=checkNumber;i++){
                char number_string[100];
                sprintf(number_string,"%d",i);
                if(write(fd[0][1],number_string,10)==-1){
                    perror("Error: failed to write to pipe -");
                    exit(-1);
                }
            }
            if(close(fd[0][1])==-1){//closing the write of the first pipe after finishing writing
                perror("Error: closing the write pipe [parent]-");
                exit(-1);
            }
        }else{
            char temp_parent[100];//stores the temporary value from the pipe read
            if(close(fd[0][0])==-1){//closing the read of the first pipe
                perror("Error: closing the write first pipe [parent]-");
                exit(-1);
            }
            if(close(fd[1][1])==-1){//closing the write of the second pipe
                perror("Error: closing the write second pipe [parent]-");
                exit(-1);
            }

            while(read(fd[1][0],temp_parent,10)>0){//reading the data from the second pipe
                //write the data to the first pipe so that it can be read by the child for filtering
                if(write(fd[0][1],temp_parent,10)==-1){
                    perror("Error: failed to write to pipe -");
                    exit(-1);
                }
                printf("[%d] parent received %s\n",getpid(),temp_parent);
            }


            if(close(fd[0][1])==-1){//closing the write of the first pipe
                perror("Error: closing the read first pipe [parent]-");
                exit(-1);
            }
            if(close(fd[1][0])==-1){//closing the read of the second pipe
                perror("Error: closing the read second pipe [parent]-");
                exit(-1);
            }
        }
    }else if(child==0){

        char temp[100];//stores the temporary value from the pipe read
        if(close(fd[0][1])==-1){//closing the write of the first pipe
            perror("Error: closing the write pipe [child]-");
            exit(-1);
        }
        if(close(fd[1][0])==-1){//closing the read of the second pipe
            perror("Error: closing the write pipe [child]-");
            exit(-1);
        }

        if(!(read(fd[0][0],temp,10)>0)){//the first number read specifies the overall filter
            fprintf(stderr,"Error: while reading the filter");
            exit(-1);
        }
        filter=strtol(temp,NULL,10);//storing the first read as the filter
        while(read(fd[0][0],temp,10)>0){//reading the rest of the data for filtering
            printf("[%d] child received %s\n",getpid(),temp);
            if(strtol(temp,NULL,10)%filter!=0){//checking to see if the read number is divisible by the filter
                //if not, we write it to the second pipe
                if(write(fd[1][1],temp,10)==-1){
                    perror("Error: failed to write to pipe -");
                    exit(-1);
                }
            }
        }

        if(close(fd[1][1])==-1){//closing the write of the second pipe
            perror("Error: closing the read pipe [child]-");
            exit(-1);
        }
        if(close(fd[0][0])==-1){//closing the read of the first pipe
            perror("Error: closing the read pipe [child]-");
            exit(-1);
        }
    }
}while(0 && child==0 && checkNumber/2<=filter);

}

Answer 1

I found the solution.But the credit goes to Barmar for helping me and giving me hints of the possible problems in the comments. The problem as Barmar actually hinted is "you're getting stuck when you write to fd[1][1]. The problem is the process that's reading from fd[1][0]". Apparently, the write terminated the program knowing that there is no other processes to read the data(parent process finished executing or the process reading fd[1][0]).Therefore, Adding wait in the parent process(the other process) would solve the issue.