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/*
* Copyright (C) Igor Sysoev
* Copyright (C) NGINX, Inc.
*/
#include <nxt_main.h>
/*
* Signals are handled only via a main thread event engine work queue.
* There are three ways to route signals to the work queue:
*
* 1) Using signal event notifications if an event facility supports it:
* kqueue and epoll/signalfd. This method is used regardless of thread mode.
*
* 2) Multi-threaded mode: a dedicated signal thread which waits in sigwait()
* and post a signal number to the main thread event engine.
*
* 3) Single-threaded mode: a signal handler which posts a signal number
* to the event engine.
*/
static nxt_int_t nxt_signal_action(int signo, void (*handler)(int));
static void nxt_signal_thread(void *data);
nxt_event_signals_t *
nxt_event_engine_signals(const nxt_sig_event_t *sigev)
{
nxt_event_signals_t *signals;
signals = nxt_zalloc(sizeof(nxt_event_signals_t));
if (signals == NULL) {
return NULL;
}
signals->sigev = sigev;
if (nxt_signal_action(SIGSYS, SIG_IGN) != NXT_OK) {
goto fail;
}
if (nxt_signal_action(SIGPIPE, SIG_IGN) != NXT_OK) {
goto fail;
}
sigemptyset(&signals->sigmask);
while (sigev->signo != 0) {
sigaddset(&signals->sigmask, sigev->signo);
sigev++;
}
if (sigprocmask(SIG_BLOCK, &signals->sigmask, NULL) != 0) {
nxt_main_log_alert("sigprocmask(SIG_BLOCK) failed %E", nxt_errno);
goto fail;
}
return signals;
fail:
nxt_free(signals);
return NULL;
}
static nxt_int_t
nxt_signal_action(int signo, void (*handler)(int))
{
struct sigaction sa;
nxt_memzero(&sa, sizeof(struct sigaction));
sigemptyset(&sa.sa_mask);
sa.sa_handler = handler;
if (sigaction(signo, &sa, NULL) == 0) {
return NXT_OK;
}
nxt_main_log_alert("sigaction(%d) failed %E", signo, nxt_errno);
return NXT_ERROR;
}
static void
nxt_signal_handler(int signo)
{
nxt_thread_t *thr;
thr = nxt_thread();
/* Thread is running in a single context now. */
thr->time.signal++;
nxt_thread_time_update(thr);
nxt_main_log_error(NXT_LOG_INFO, "signal handler: %d", signo);
nxt_event_engine_signal(thr->engine, signo);
thr->time.signal--;
}
nxt_int_t
nxt_signal_thread_start(nxt_event_engine_t *engine)
{
nxt_thread_link_t *link;
const nxt_sig_event_t *sigev;
if (engine->signals->process == nxt_pid) {
return NXT_OK;
}
if (sigprocmask(SIG_BLOCK, &engine->signals->sigmask, NULL) != 0) {
nxt_main_log_alert("sigprocmask(SIG_BLOCK) failed %E", nxt_errno);
return NXT_ERROR;
}
/*
* kqueue sets signal handlers to SIG_IGN and sigwait() ignores
* them after the switch of event facility from "kqueue" to "select".
*/
for (sigev = engine->signals->sigev; sigev->signo != 0; sigev++) {
if (nxt_signal_action(sigev->signo, nxt_signal_handler) != NXT_OK) {
return NXT_ERROR;
}
}
link = nxt_zalloc(sizeof(nxt_thread_link_t));
if (nxt_fast_path(link != NULL)) {
link->start = nxt_signal_thread;
link->work.data = engine;
if (nxt_thread_create(&engine->signals->thread, link) == NXT_OK) {
engine->signals->process = nxt_pid;
return NXT_OK;
}
}
return NXT_ERROR;
}
static void
nxt_signal_thread(void *data)
{
int signo;
nxt_err_t err;
nxt_thread_t *thr;
nxt_event_engine_t *engine;
engine = data;
thr = nxt_thread();
nxt_main_log_debug("signal thread");
for ( ;; ) {
err = sigwait(&engine->signals->sigmask, &signo);
nxt_thread_time_update(thr);
if (nxt_fast_path(err == 0)) {
nxt_main_log_error(NXT_LOG_INFO, "signo: %d", signo);
nxt_event_engine_signal(engine, signo);
} else {
nxt_main_log_alert("sigwait() failed %E", err);
}
}
}
void
nxt_signal_thread_stop(nxt_event_engine_t *engine)
{
nxt_thread_handle_t thread;
thread = engine->signals->thread;
nxt_thread_cancel(thread);
nxt_thread_wait(thread);
}
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