pipe 실습

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/wait.h>
#include <unistd.h>
#include <sys/stat.h>
#define MAXLINE 100

static void do_exit(const char *s);

int main(){
        int r, m, i, j;
        int childstatus;

        //printf("입력할 숫자의 개수: ");
        //scanf("%d", &n);
        //if(!n) do_exit("n value null");

        //int *num = malloc(sizeof(int) * n);
        //if(!num) do_eixt("malloc error");

        //for(i=0; i<n; i++){
        //      scanf("%d", &num[i]);
        //}

        printf("프로세스 개수(1~10): ");
        scanf("%d", &m);
        if(m<1 || m>10) do_exit("m range over");
        pid_t pid[m];

        for(i=0; i<m; i++){
                int fd1[2], fd2[2];
                if(pipe(fd1) < 0) do_exit("pipe error");
                if(pipe(fd2) < 0) do_exit("pipe error");

                pid[i] = fork();
                if(pid[i] < 0){
                        do_exit("fork error");
                } else if(pid[i] == 0){
                        char getnum[MAXLINE];
                        close(fd1[1]);

                        if((r = read(fd1[0], getnum, MAXLINE)) > 0);

                        //printf("get num: %s\n", getnum);
                        close(fd1[0]);

                        int childsum = 0, cnt = 0;
                        char *arr = strtok(getnum, " ");
                        int setsum[MAXLINE];

                        while(arr != NULL){
                                setsum[cnt] = atoi(arr);
                                cnt++;
                                //printf("arr: %s\n", arr);
                                arr = strtok(NULL, " ");
                        }

                        //printf("strlen :%d\n", cnt);

                        for(j=i*cnt/m; j<(i+1)*cnt/m;j++){
                                printf("\ni: %d, m: %d, cnt: %d, %d, %d\n", i, m, cnt, i*cnt/m, (i+1)*cnt/m);
                                childsum += setsum[i];
                        }

                        write(fd2[1], (char *)&childsum, sizeof childsum);
                        printf("csum: %d\n", childsum);
                        //printf("\ni: %d, m: %d, n: %d, %d, %d\n", i, m, n, i*n/m, (i+1)*n/m);
                        //printf("child: , %d\n\n", (int)getpid());

                        exit(0);
                } else{
                        int sum = 0, n;
                        //printf("parent: %d - child: %d\n\n", (int)getpid() , (int)pid[i]);

                        close(fd1[0]);
                        close(fd2[1]);

                        printf("입력할 숫자의 개수: ");
                        scanf("%d", &n);
                        if(!n) do_exit("n value null");

                        int *num = malloc(MAXLINE);
                        if(!num) do_exit("malloc error");

                        char *setnum = malloc(MAXLINE);
                        if(!setnum) do_exit("malloc error");


                        for(i=0; i<n; i++){
                                scanf("%d", &num[i]);
                                char tmp[MAXLINE];
                                sprintf(tmp, "%d", num[i]);
                                strcat(setnum, tmp);
                                strcat(setnum, " ");
                        }
                        write(fd1[1], setnum, MAXLINE);

                        pid_t cstatus = wait(&childstatus);

                        int r;
                        char getsum[MAXLINE];
                        struct stat st;

                        if(fstat(fd2[0], &st) < 0) do_exit("stat error");
                        if(st.st_size > MAXLINE) do_exit("fd[0] len error");

                        while((r = read(fd2[0], getsum, MAXLINE)) > 0){
                                printf("\nchild sum: %s\n", getsum);
                                sum+= atoi(getsum);
                        }
                        close(fd2[0]);

                        printf("parent sum: %d\n", sum);

                        if(WIFEXITED(childstatus)){
                                printf("exit, status=%d\n", WEXITSTATUS(childstatus));
                        }else{
                                printf("abnormal exit\n");
                        }
                }
        }