#include <stdlib.h>

#include "_pty.h"

#define PIPE_READ 0
#define PIPE_WRITE 1

/* Allocate a PTY and fork, giving fdmx (master) to the parent
 * and binding the child's stdin/stdout to fds (slave).
 * Return value is indentical to fork(2).
 * NOTE: This function is my alternative to GLibC's
 * NOTE: forkpty() function. It exists as a learning resource.
 * REF: https://sourceware.org/git/glibc.git -> ./login/forkpty.c
 */
pid_t forkepty(int *fdmx, int *fderr) {
  // master/slave, and stderr pipe fds
  int epipe[2];
  pid_t pid;

  if (pipe(epipe) == -1)
    return EXIT_FAILURE;
  switch (pid = forkmkpty(fdmx)) {
  case -1:
    /* forkmkpty() will close fdmx/fds for us */
    close(epipe[PIPE_READ]);
    close(epipe[PIPE_WRITE]);
    return -1;
  case 0:
    /* Child Process */
    /* forkmkpty() will close fdmx for us */
    close(epipe[PIPE_READ]);
    BIND(epipe[PIPE_WRITE], STDERR_FILENO);
    break;

  default:
    /* Parent Process */
    /* forkmkpty() will close fds for us */
    close(epipe[PIPE_WRITE]);
    *fderr = epipe[PIPE_READ];
    break;
  }

  /* Both Processes */
  return pid;
}