static void
fork_blocking_child(
blocking_child * c
)
{
static int atexit_installed;
static int blocking_pipes[4] = { -1, -1, -1, -1 };
int rc;
int was_pipe;
int is_pipe;
int saved_errno = 0;
int childpid;
int keep_fd;
int fd;
/*
* parent and child communicate via a pair of pipes.
*
* 0 child read request
* 1 parent write request
* 2 parent read response
* 3 child write response
*/
if (-1 == c->req_write_pipe) {
rc = pipe_socketpair(&blocking_pipes[0], &was_pipe);
if (0 != rc) {
saved_errno = errno;
} else {
rc = pipe_socketpair(&blocking_pipes[2], &is_pipe);
if (0 != rc) {
saved_errno = errno;
close(blocking_pipes[0]);
close(blocking_pipes[1]);
} else {
INSIST(was_pipe == is_pipe);
}
}
if (0 != rc) {
errno = saved_errno;
msyslog(LOG_ERR, "unable to create worker pipes: %m");
exit(1);
}
/*
* Move the descriptors the parent will keep open out of the
* low descriptors preferred by C runtime buffered FILE *.
*/
c->req_write_pipe = move_fd(blocking_pipes[1]);
c->resp_read_pipe = move_fd(blocking_pipes[2]);
/*
* wake any worker child on orderly shutdown of the
* daemon so that it can notice the broken pipes and
* go away promptly.
*/
if (!atexit_installed) {
atexit(&send_worker_home_atexit);
atexit_installed = TRUE;
}
}
#ifdef HAVE_DROPROOT
/* defer the fork until after root is dropped */
if (droproot && !root_dropped)
return;
#endif
if (syslog_file != NULL)
fflush(syslog_file);
fflush(stdout);
fflush(stderr);
signal_no_reset(SIGCHLD, SIG_IGN);
childpid = fork();
if (-1 == childpid) {
msyslog(LOG_ERR, "unable to fork worker: %m");
exit(1);
}
if (childpid) {
/* this is the parent */
TRACE(1, ("forked worker child (pid %d)\n", childpid));
c->pid = childpid;
c->ispipe = is_pipe;
/* close the child's pipe descriptors. */
close(blocking_pipes[0]);
close(blocking_pipes[3]);
memset(blocking_pipes, -1, sizeof(blocking_pipes));
/* wire into I/O loop */
(*addremove_io_fd)(c->resp_read_pipe, is_pipe, FALSE);
return; /* parent returns */
}
/*
* The parent gets the child pid as the return value of fork().
* The child must work for it.
*/
c->pid = getpid();
worker_process = TRUE;
/*
* In the child, close all files except stdin, stdout, stderr,
* and the two child ends of the pipes.
*/
DEBUG_INSIST(-1 == c->req_read_pipe);
DEBUG_INSIST(-1 == c->resp_write_pipe);
c->req_read_pipe = blocking_pipes[0];
c->resp_write_pipe = blocking_pipes[3];
kill_asyncio(0);
closelog();
if (syslog_file != NULL) {
fclose(syslog_file);
syslog_file = NULL;
syslogit = TRUE;
}
keep_fd = max(c->req_read_pipe, c->resp_write_pipe);
for (fd = 3; fd < keep_fd; fd++)
if (fd != c->req_read_pipe &&
fd != c->resp_write_pipe)
close(fd);
close_all_beyond(keep_fd);
/*
* We get signals from refclock serial I/O on NetBSD in the
* worker if we do not reset SIGIO's handler to the default.
* It is not conditionalized for NetBSD alone because on
* systems where it is not needed, it is harmless, and that
* allows us to handle unknown others with NetBSD behavior.
* [Bug 1386]
*/
#if defined(USE_SIGIO)
signal_no_reset(SIGIO, SIG_DFL);
#elif defined(USE_SIGPOLL)
signal_no_reset(SIGPOLL, SIG_DFL);
#endif
signal_no_reset(SIGHUP, worker_sighup);
init_logging("ntp_intres", 0, FALSE);
setup_logfile(NULL);
/*
* And now back to the portable code
*/
exit_worker(blocking_child_common(c));
}
static void
start_blocking_thread_internal(
blocking_child * c
)
{
pthread_attr_t thr_attr;
int rc;
int pipe_ends[2]; /* read then write */
bool is_pipe;
int flags;
size_t stacksize;
sigset_t saved_sig_mask;
rc = pipe_socketpair(&pipe_ends[0], &is_pipe);
if (0 != rc) {
msyslog(LOG_ERR, "start_blocking_thread: pipe_socketpair() %m");
exit(1);
}
c->resp_read_pipe = move_fd(pipe_ends[0]);
c->resp_write_pipe = move_fd(pipe_ends[1]);
c->ispipe = is_pipe;
flags = fcntl(c->resp_read_pipe, F_GETFL, 0);
if (-1 == flags) {
msyslog(LOG_ERR, "start_blocking_thread: fcntl(F_GETFL) %m");
exit(1);
}
rc = fcntl(c->resp_read_pipe, F_SETFL, O_NONBLOCK | flags);
if (-1 == rc) {
msyslog(LOG_ERR,
"start_blocking_thread: fcntl(F_SETFL, O_NONBLOCK) %m");
exit(1);
}
(*addremove_io_fd)(c->resp_read_pipe, c->ispipe, false);
pthread_attr_init(&thr_attr);
pthread_attr_setdetachstate(&thr_attr, PTHREAD_CREATE_DETACHED);
rc = pthread_attr_getstacksize(&thr_attr, &stacksize);
if (0 != rc) {
errno = rc;
msyslog(LOG_ERR,
"start_blocking_thread: pthread_attr_getstacksize %m");
} else if (stacksize < THREAD_MINSTACKSIZE) {
rc = pthread_attr_setstacksize(&thr_attr,
THREAD_MINSTACKSIZE);
if (0 != rc) {
errno = rc;
msyslog(LOG_ERR,
"start_blocking_thread: pthread_attr_setstacksize(0x%lx -> 0x%lx) %m",
(u_long)stacksize,
(u_long)THREAD_MINSTACKSIZE);
}
}
pthread_attr_setscope(&thr_attr, PTHREAD_SCOPE_SYSTEM);
c->thread_ref = emalloc_zero(sizeof(*c->thread_ref));
block_thread_signals(&saved_sig_mask);
rc = pthread_create(c->thread_ref, &thr_attr,
&blocking_thread, c);
if (0 != rc) {
if (EAGAIN == errno) {
msyslog(LOG_ERR, "EAGAIN from pthread_create(), probably out of (locked) memory");
} else {
msyslog(LOG_ERR, "pthread_create() blocking child: %m");
}
exit(1);
}
pthread_sigmask(SIG_SETMASK, &saved_sig_mask, NULL);
pthread_attr_destroy(&thr_attr);
}
