Parent从文件中读取操作，子项将其与bc相加

Question

我正在尝试创建一个程序，其中父项从文件中读取一些操作，使用管道将它们传递给子项，并且子项使用bc进行所有操作。稍后，孩子必须将其传递回父母，并且必须将其写在文件上。

但是，当我执行它时，我没有得到任何结果，也不知道问题出在哪里。孩子似乎正确地接受了操作，但具有'EXT'字符。

当父进程没有从文件中读取时，我的代码工作正常，问题是当我尝试从文件中读取时。

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

#define EOL '
'

int main(int argc, char *argv[]){
    int tube1[2];
    int tube2[2];
    int fID;
    pipe(tube1);
    pipe(tube2);

    if(argc != 2){
        perror("./yourProgram.c [origin]");
        exit(EXIT_FAILURE);
    }

    if (fork() == 0){
        //Child Process

        close(tube1[1]); // writing end of the pipe
        dup2(tube1[0], 0);  // stdin ----> pipe reading end

        close(tube2[0]); // reading end of the pipe
        dup2(tube2[1], 1);  // stdout ---> pipe writing end

        //Execute and write the output in the tube2
        execlp("bc", "bc", "-q", NULL);
    }else {
        //Parent Process

        close(tube1[0]); // reading end of the pipe
        //dup2(tube1[1], 1); // stdout ---> pipe writing end

        close(tube2[1]); // reading end of the pipe
        //dup2(tube1[1], 1); // stdout ---> pipe writing end

     //Files
        //Destiny
        char *destiny = "final.txt";
        int destinyFile = open(destiny, O_WRONLY | O_CREAT | O_TRUNC, 0644);

        //Origin
        char *origin = argv[1];
        int originFile = open(origin, O_RDONLY);

        //Variables
        char block;
        char result;
        char buffer[4096];
        int i = 0;
        int numbytes;

        while(numbytes = read(originFile, &block, sizeof(block)) > 0){
            if(block == EOL){

                //Write on the tube, so the child can read it
                if(write(tube1[1], buffer, strlen(buffer)) == -1){
                    perror("error en write en pipe");
                    exit(EXIT_FAILURE);
                }

                //Read the child's answer
                while(numbytes = read(tube2[0], &result, 1) > 0){
                    if(result != EOL){
                        //Concatenate strings as: 'X + Y = Result 
'
                        char str[80];
                        strcat(str, buffer);
                        strcat(str, " = ");
                        strcat(str, &result);
                        strcat(str, "
");

                        //Write the result in the Final File
                        if(write(destinyFile, str, strlen(str)) == -1){
                            perror("error en write en stdout");
                            exit(EXIT_FAILURE);
                        }
                    }else
                        continue;        
                }

                //Reset Buffer
                buffer[0] = '';
                i = 0;
             }else{
                buffer[i] = block;
                i = i + 1;
            }
        }
    }
}

我读到的文件是：

2+3
4*5
8/2
quit