dbus_bool_t
_dbus_become_daemon (const DBusString *pidfile,
int print_pid_fd,
DBusError *error)
{
const char *s;
pid_t child_pid;
int dev_null_fd;
_dbus_verbose ("Becoming a daemon...\n");
_dbus_verbose ("chdir to /\n");
if (chdir ("/") < 0)
{
dbus_set_error (error, DBUS_ERROR_FAILED,
"Could not chdir() to root directory");
return FALSE;
}
_dbus_verbose ("forking...\n");
switch ((child_pid = fork ()))
{
case -1:
_dbus_verbose ("fork failed\n");
dbus_set_error (error, _dbus_error_from_errno (errno),
"Failed to fork daemon: %s", _dbus_strerror (errno));
return FALSE;
break;
case 0:
_dbus_verbose ("in child, closing std file descriptors\n");
/* silently ignore failures here, if someone
* doesn't have /dev/null we may as well try
* to continue anyhow
*/
dev_null_fd = open ("/dev/null", O_RDWR);
if (dev_null_fd >= 0)
{
dup2 (dev_null_fd, 0);
dup2 (dev_null_fd, 1);
s = _dbus_getenv ("DBUS_DEBUG_OUTPUT");
if (s == NULL || *s == '\0')
dup2 (dev_null_fd, 2);
else
_dbus_verbose ("keeping stderr open due to DBUS_DEBUG_OUTPUT\n");
}
/* Get a predictable umask */
_dbus_verbose ("setting umask\n");
umask (022);
break;
default:
if (pidfile)
{
_dbus_verbose ("parent writing pid file\n");
if (!_dbus_write_pid_file (pidfile,
child_pid,
error))
{
_dbus_verbose ("pid file write failed, killing child\n");
kill (child_pid, SIGTERM);
return FALSE;
}
}
/* Write PID if requested */
if (print_pid_fd >= 0)
{
DBusString pid;
int bytes;
if (!_dbus_string_init (&pid))
{
_DBUS_SET_OOM (error);
kill (child_pid, SIGTERM);
return FALSE;
}
if (!_dbus_string_append_int (&pid, child_pid) ||
!_dbus_string_append (&pid, "\n"))
{
_dbus_string_free (&pid);
_DBUS_SET_OOM (error);
kill (child_pid, SIGTERM);
return FALSE;
}
bytes = _dbus_string_get_length (&pid);
if (_dbus_write_socket (print_pid_fd, &pid, 0, bytes) != bytes)
{
dbus_set_error (error, DBUS_ERROR_FAILED,
"Printing message bus PID: %s\n",
_dbus_strerror (errno));
_dbus_string_free (&pid);
kill (child_pid, SIGTERM);
return FALSE;
}
_dbus_string_free (&pid);
}
_dbus_verbose ("parent exiting\n");
_exit (0);
break;
}
_dbus_verbose ("calling setsid()\n");
if (setsid () == -1)
_dbus_assert_not_reached ("setsid() failed");
return TRUE;
}
/**
* Writes the given pid_to_write to a pidfile (if non-NULL) and/or to a
* pipe (if non-NULL). Does nothing if pidfile and print_pid_pipe are both
* NULL.
*
* @param pidfile the file to write to or #NULL
* @param print_pid_pipe the pipe to write to or #NULL
* @param pid_to_write the pid to write out
* @param error error on failure
* @returns FALSE if error is set
*/
dbus_bool_t
_dbus_write_pid_to_file_and_pipe (const DBusString *pidfile,
DBusPipe *print_pid_pipe,
dbus_pid_t pid_to_write,
DBusError *error)
{
if (pidfile)
{
_dbus_verbose ("writing pid file %s\n", _dbus_string_get_const_data (pidfile));
if (!_dbus_write_pid_file (pidfile,
pid_to_write,
error))
{
_dbus_verbose ("pid file write failed\n");
_DBUS_ASSERT_ERROR_IS_SET(error);
return FALSE;
}
}
else
{
_dbus_verbose ("No pid file requested\n");
}
if (print_pid_pipe != NULL && _dbus_pipe_is_valid (print_pid_pipe))
{
DBusString pid;
int bytes;
_dbus_verbose ("writing our pid to pipe %d\n",
print_pid_pipe->fd);
if (!_dbus_string_init (&pid))
{
_DBUS_SET_OOM (error);
return FALSE;
}
if (!_dbus_string_append_int (&pid, pid_to_write) ||
!_dbus_string_append (&pid, "\n"))
{
_dbus_string_free (&pid);
_DBUS_SET_OOM (error);
return FALSE;
}
bytes = _dbus_string_get_length (&pid);
if (_dbus_pipe_write (print_pid_pipe, &pid, 0, bytes, error) != bytes)
{
/* _dbus_pipe_write sets error only on failure, not short write */
if (error != NULL && !dbus_error_is_set(error))
{
dbus_set_error (error, DBUS_ERROR_FAILED,
"Printing message bus PID: did not write enough bytes\n");
}
_dbus_string_free (&pid);
return FALSE;
}
_dbus_string_free (&pid);
}
else
{
_dbus_verbose ("No pid pipe to write to\n");
}
return TRUE;
}
