pty_reader.cpp

// clang++ -Wno-writable-strings pty_reader.cpp -lutil -o pty_reader
#include <stdio.h>
#include <unistd.h>
#include <pty.h>

int main(){
    fprintf(stdout, "READER...\n");
    fflush(stdout);
    
    int master = 0;
    
    pid_t child_pid = forkpty(&master, NULL, NULL, NULL);
    if (child_pid == -1){
        fprintf(stdout, "failed to fork\n");
        return(0);
    }
    
    if (child_pid == 0){
        char  *argv[] = {
            "sh",
            "-c",
            "./exerciser",
            0
        };
        
        if (execv("/bin/sh", argv) == -1){
            fprintf(stdout, "failed to execv\n");
            return(0);
        }
    }
    else{
        char buffer[1024];
        int capacity = sizeof(buffer);
        for (;;){
            ssize_t num = read(master, buffer, capacity);
            if (num == -1){
                fprintf(stdout, "read error\n"); // This likely means that the process has closed the pty
                return(0);
            }
            else if (num == 0){
                break;
            }
            else{
                fprintf(stdout, "%.*s", (int)num, buffer);
                fflush(stdout);
            }
        }
    }
    
    return(0);
}