GLibclear_fd

If fd_ptr points to a file descriptor, close it and return whether closing it was successful, like g_close(). If fd_ptr points to a negative number, return TRUE without closing anything. In both cases, set fd_ptr to -1 before returning.

Like g_close(), if closing the file descriptor fails, the error is stored in both %errno and error. If this function succeeds, %errno is undefined.

On POSIX platforms, this function is async-signal safe if error is NULL and fd_ptr points to either a negative number or a valid open file descriptor. This makes it safe to call from a signal handler or a GSpawnChildSetupFunc under those conditions. See signal(7) and signal-safety(7) for more details.

It is a programming error for fd_ptr to point to a non-negative number that is not a valid file descriptor.

A typical use of this function is to clean up a file descriptor at the end of its scope, whether it has been set successfully or not:

gboolean
operate_on_fd (GError **error)
{
  gboolean ret = FALSE;
  int fd = -1;

  fd = open_a_fd (error);

  if (fd < 0)
    goto out;

  if (!do_something (fd, error))
    goto out;

  if (!g_clear_fd (&fd, error))
    goto out;

  ret = TRUE;

out:
  // OK to call even if fd was never opened or was already closed
  g_clear_fd (&fd, NULL);
  return ret;
}

This function is also useful in conjunction with #g_autofd.

Available since: 2.76

This function is not directly available to language bindings.