Help managing child processes (I think)

[hinesro]

Like a few others on here, I'm writing a basic Unix shell. Most of my commands work, including redirection, such as "ls > testfile". The problem is, after one of these redirection commands, my prompt icon disappears. If I enter some text it says "write error: Bad file descriptor", and after that is unresponsive.

After spending some time debugging, something is definitely going wrong when I attempt to close the open file descriptors. Still trying to narrow it down further but I can't get any response from close().

// File redirection example
if (strcmp(args[1], ">") == 0) {
    fd = open(args[2], O_WRONLY|O_CREAT|O_TRUNC, 0644); 

    if (fd == -1) {
        exitStatus = 1;
    }

    fd2 = dup2(fd, 1);

    if (fd == -1) {
        exitStatus = 1;
    }

    args[1] = NULL;
    exitStatus = launch(args); 
    close(fd);
    close(fd2);

    // It never makes it to this point
}

// Job launch example
int launch(char **args) {
    pid_t pid, wpid;
    int status, exitStatus = 0;


    pid = fork();
    if (pid == 0) { 
        //printf("This is the child\n");
        if (execvp(args[0], args) == -1) { 
            printf("Command not recognized\n");
            exit(1); 
        }
    } else if (pid < 0) { 
        perror("smallsh");
    } else { 
        do {
            wpid = waitpid(pid, &status, WUNTRACED); 
        } while (!WIFEXITED(status) && !WIFSIGNALED(status)); 
    }


    if (status != 0 || WIFSIGNALED(status)) exitStatus = 1;


    return exitStatus;
}

[hinesro]

I'm still stumped, it seems as though close(fd) is breaking the program. Can anyone see what I'm doing wrong?

[hinesro]

As a workaround, I had to manually restore stdout. It works for now but I'm still confused about why that didn't happen when close() was called.

if (numArgs == 3) {
    int saved_stdout; // Save standard output to be restored after redirection
    saved_stdout = dup(1);


    if (strcmp(args[1], ">") == 0) {
        fd = open(args[2], O_WRONLY|O_CREAT|O_TRUNC, 0644); 


        dup2(fd, 1); // Point stdout to this file


        close(fd); // Close unused file descriptor


        exitStatus = launch(args); // Launch the command
    }

    /* Restore stdout */
    dup2(saved_stdout, 1);
    close(saved_stdout);
}