/**
* Return newly allocated buffer holding the name of this process's state file.
*
* (This can't reliably be static because we might fork...)
**/
static int dcc_get_state_filename(char **fname)
{
int ret;
char *dir;
if ((ret = dcc_get_state_dir(&dir)))
return ret;
if (asprintf(fname, "%s/%s%ld",
dir, dcc_state_prefix, (long) getpid()) == -1) {
return EXIT_OUT_OF_MEMORY;
}
return 0;
}
/*
* Try to setup dnotify on the state directory. This returns the
* descriptor of a pipe in @p dummy_fd. Every time the state changes,
* a single byte is written to this pipe. A caller who select()s on
* the pipe will therefore be woken every time there is a change.
*
* If we can do dnotify, create the dummy pipe and turn it on.
*
* @fixme One problem here is that if the state directory is deleted
* and recreated, then we'll never notice and find the new one. I
* don't know of any good fix, other than perhaps polling every so
* often. So just don't do that.
*
* @fixme If this function is called repeatedly it will leak FDs.
*
* @todo Reimplement this on top of kevent for BSD.
*/
int dcc_mon_setup_notify (int *dummy_fd)
{
#ifdef F_NOTIFY
char *state_dir;
int ret;
int fd;
if (signal (SIGIO, dcc_mon_siginfo_handler) == SIG_ERR) {
rs_log_error ("signal(SIGINFO) failed: %s", strerror(errno));
return EXIT_IO_ERROR;
}
if (pipe ((int *) pipe_fd) == -1) {
rs_log_error ("pipe failed: %s", strerror (errno));
return EXIT_IO_ERROR;
}
*dummy_fd = pipe_fd[0]; /* read end */
dcc_set_nonblocking (pipe_fd[0]);
dcc_set_nonblocking (pipe_fd[1]);
if ((ret = dcc_get_state_dir (&state_dir)))
return ret;
if ((fd = open (state_dir, O_RDONLY)) == -1) {
rs_log_error ("failed to open %s: %s", state_dir, strerror (errno));
free (state_dir);
return EXIT_IO_ERROR;
}
/* CAUTION! Signals can start arriving immediately. Be ready. */
if (fcntl (fd, F_NOTIFY, DN_RENAME|DN_DELETE|DN_MULTISHOT) == -1) {
rs_log_warning ("setting F_NOTIFY failed: %s",
strerror (errno));
free (state_dir);
return EXIT_IO_ERROR;
}
return 0;
#else /* F_NOTIFY */
return EXIT_IO_ERROR;
#endif /* F_NOTIFY */
}
