pty/driver.c at master · abligh/pty · GitHub

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#include "apue.h"

void
do_driver (char *driver)
{
  pid_t child;
  int pipe[2];

  /*
   * Create a full-duplex pipe to communicate with the driver.
   */
  if (fd_pipe (pipe) < 0)
    err_sys ("can't create stream pipe");

  if ((child = fork ()) < 0)
    {
      err_sys ("fork error");
    }
  else if (child == 0)
    {				/* child */
      close (pipe[1]);

      /* stdin for driver */
      if (dup2 (pipe[0], STDIN_FILENO) != STDIN_FILENO)
	err_sys ("dup2 error to stdin");

      /* stdout for driver */
      if (dup2 (pipe[0], STDOUT_FILENO) != STDOUT_FILENO)
	err_sys ("dup2 error to stdout");
      if (pipe[0] != STDIN_FILENO && pipe[0] != STDOUT_FILENO)
	close (pipe[0]);

      /* leave stderr for driver alone */
      execlp (driver, driver, (char *) 0);
      err_sys ("execlp error for: %s", driver);
    }

  close (pipe[0]);		/* parent */
  if (dup2 (pipe[1], STDIN_FILENO) != STDIN_FILENO)
    err_sys ("dup2 error to stdin");
  if (dup2 (pipe[1], STDOUT_FILENO) != STDOUT_FILENO)
    err_sys ("dup2 error to stdout");
  if (pipe[1] != STDIN_FILENO && pipe[1] != STDOUT_FILENO)
    close (pipe[1]);

  /*
   * Parent returns, but with stdin and stdout connected
   * to the driver.
   */
}