links/select.c

/* select.c
 * Select Loop
 * (c) 2002 Mikulas Patocka
 * This file is a part of the Links program, released under GPL.
 */

#include "links.h"

/*
#define DEBUG_CALLS
*/

#ifdef USE_LIBEVENT
#if defined(evtimer_set) && !defined(timeout_set)
#define timeout_set	evtimer_set
#endif
#if defined(evtimer_add) && !defined(timeout_add)
#define timeout_add	evtimer_add
#endif
#if defined(evtimer_del) && !defined(timeout_del)
#define timeout_del	evtimer_del
#endif
#endif

struct thread {
	void (*read_func)(void *);
	void (*write_func)(void *);
	void *data;
#ifdef USE_LIBEVENT
	struct event *read_event;
	struct event *write_event;
#endif
};

static struct thread *threads = DUMMY;
static int n_threads = 0;

static fd_set w_read;
static fd_set w_write;

static fd_set x_read;
static fd_set x_write;

static int w_max;

struct timer {
	list_entry_1st
	uttime interval;
	void (*func)(void *);
	void *data;
	list_entry_last
};

static struct list_head timers = { &timers, &timers };


#if !defined(OS2) && !defined(OPENVMS)
void portable_sleep(unsigned msec)
{
	struct timeval tv;
	int rs;
	block_signals(0, 0);
	tv.tv_sec = msec / 1000;
	tv.tv_usec = msec % 1000 * 1000;
	EINTRLOOP(rs, select(0, NULL, NULL, NULL, &tv));
	unblock_signals();
}
#endif

static int can_do_io(int fd, int wr, int sec)
{
	fd_set fds;
	struct timeval tv, *tvp;
	int rs;

	if (fd < 0)
		internal_error("can_do_io: handle %d", fd);

#if defined(USE_POLL)
	{
		struct pollfd p;
		p.fd = fd;
		p.events = !wr ? POLLIN : POLLOUT;
		EINTRLOOP(rs, poll(&p, 1, sec < 0 ? -1 : sec * 1000));
		if (rs < 0) fatal_exit("ERROR: poll for %s (%d) failed: %s", !wr ? "read" : "write", fd, strerror(errno));
		if (!rs) return 0;
		if (p.revents & POLLNVAL) goto fallback;
		return 1;
	}
fallback:
#endif
	if (sec >= 0) {
		tv.tv_sec = sec;
		tv.tv_usec = 0;
		tvp = &tv;
	} else {
		tvp = NULL;
	}
	FD_ZERO(&fds);
	if (fd >= (int)FD_SETSIZE) {
		fatal_exit("too big handle %d", fd);
	}
	FD_SET(fd, &fds);
	if (!wr)
		EINTRLOOP(rs, select(fd + 1, &fds, NULL, NULL, tvp));
	else
		EINTRLOOP(rs, select(fd + 1, NULL, &fds, NULL, tvp));
	if (rs < 0) fatal_exit("ERROR: select for %s (%d) failed: %s", !wr ? "read" : "write", fd, strerror(errno));
	return rs;
}

int can_write(int fd)
{
	return can_do_io(fd, 1, 0);
}

int can_read_timeout(int fd, int sec)
{
	return can_do_io(fd, 0, sec);
}

int can_read(int fd)
{
	return can_do_io(fd, 0, 0);
}


int close_std_handle(int std)
{
#ifndef DOS
	int n, h, rs;
	if (std == 1)
		fflush(stdout);
	if (std == 2)
		fflush(stderr);
	n = c_open(cast_uchar "/dev/null", O_WRONLY | O_NOCTTY);
	if (n == -1)
		goto fail1;
	h = c_dup(std);
	if (h == -1)
		goto fail2;
	EINTRLOOP(rs, dup2(n, std));
	if (rs == -1)
		goto fail3;
	EINTRLOOP(rs, close(n));
	return h;

fail3:
	EINTRLOOP(rs, close(h));
fail2:
	EINTRLOOP(rs, close(n));
fail1:
#endif
	return -1;
}

void restore_std_handle(int std, int h)
{
#ifndef DOS
	int rs;
	if (std == 1)
		fflush(stdout);
	if (std == 2)
		fflush(stderr);
	if (h == -1)
		return;
	EINTRLOOP(rs, dup2(h, std));
	EINTRLOOP(rs, close(h));
#endif
}


unsigned long select_info(int type)
{
	int i, j;
	switch (type) {
		case CI_FILES:
			i = 0;
			for (j = 0; j < w_max; j++)
				if (threads[j].read_func || threads[j].write_func) i++;
			return i;
		case CI_TIMERS:
			return list_size(&timers);
		default:
			internal_error("select_info_info: bad request");
	}
	return 0;
}

struct bottom_half {
	list_entry_1st
	void (*fn)(void *);
	void *data;
	list_entry_last
};

static struct list_head bottom_halves = { &bottom_halves, &bottom_halves };

void register_bottom_half(void (*fn)(void *), void *data)
{
	struct bottom_half *bh;
	struct list_head *lbh;
	foreach(struct bottom_half, bh, lbh, bottom_halves) if (bh->fn == fn && bh->data == data) return;
	bh = mem_alloc(sizeof(struct bottom_half));
	bh->fn = fn;
	bh->data = data;
	add_to_list(bottom_halves, bh);
}

void unregister_bottom_half(void (*fn)(void *), void *data)
{
	struct bottom_half *bh;
	struct list_head *lbh;
	foreach(struct bottom_half, bh, lbh, bottom_halves) if (bh->fn == fn && bh->data == data) {
		del_from_list(bh);
		mem_free(bh);
		return;
	}
}

void check_bottom_halves(void)
{
	struct bottom_half *bh;
	void (*fn)(void *);
	void *data;
	rep:
	if (list_empty(bottom_halves)) return;
	bh = list_struct(bottom_halves.prev, struct bottom_half);
	fn = bh->fn;
	data = bh->data;
	del_from_list(bh);
	mem_free(bh);
#ifdef DEBUG_CALLS
	fprintf(stderr, "call: bh %p\n", fn);
#endif
	pr(fn(data)) {
#ifdef OOPS
		free_list(struct bottom_half, bottom_halves);
		return;
#endif
	};
#ifdef DEBUG_CALLS
	fprintf(stderr, "bh done\n");
#endif
	goto rep;
}

#define CHK_BH if (!list_empty(bottom_halves)) check_bottom_halves()


static void restrict_fds(void)
{
#if defined(RLIMIT_OFILE) && !defined(RLIMIT_NOFILE)
#define RLIMIT_NOFILE RLIMIT_OFILE
#endif
#if defined(HAVE_GETRLIMIT) && defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE)
	struct rlimit limit;
	int rs;
	EINTRLOOP(rs, getrlimit(RLIMIT_NOFILE, &limit));
	if (rs)
		goto skip_limit;
	if (limit.rlim_cur > FD_SETSIZE) {
		limit.rlim_cur = FD_SETSIZE;
		EINTRLOOP(rs, setrlimit(RLIMIT_NOFILE, &limit));
	}
skip_limit:;
#endif
}

unsigned char *sh_file;
int sh_line;

#ifdef USE_LIBEVENT

static int event_enabled = 0;

#ifndef HAVE_EVENT_GET_STRUCT_EVENT_SIZE
#define sizeof_struct_event		sizeof(struct event)
#else
#define sizeof_struct_event		(event_get_struct_event_size())
#endif

static inline struct event *timer_event(struct timer *tm)
{
	return (struct event *)((unsigned char *)tm - sizeof_struct_event);
}

#ifdef HAVE_EVENT_BASE_SET
static struct event_base *event_base;
#endif

static void event_callback(int h, short ev, void *data)
{
#ifndef EV_PERSIST
	if (event_add((struct event *)data, NULL) == -1)
		fatal_exit("ERROR: event_add failed: %s", strerror(errno));
#endif
	if (!(ev & EV_READ) == !(ev & EV_WRITE))
		internal_error("event_callback: invalid flags %d on handle %d", (int)ev, h);
	if (ev & EV_READ) {
#if defined(HAVE_LIBEV)
		/* Old versions of libev badly interact with fork and fire
		 * events spuriously. */
		if (ev_version_major() < 4 && !can_read(h)) return;
#endif
		pr(threads[h].read_func(threads[h].data)) { }
	} else {
#if defined(HAVE_LIBEV)
		/* Old versions of libev badly interact with fork and fire
		 * events spuriously. */
		if (ev_version_major() < 4 && !can_write(h)) return;
#endif
		pr(threads[h].write_func(threads[h].data)) { }
	}
	CHK_BH;
}

static void timer_callback(int h, short ev, void *data)
{
	struct timer *tm = data;
	pr(tm->func(tm->data)) { }
	kill_timer(tm);
	CHK_BH;
}

static void set_event_for_action(int h, void (*func)(void *), struct event **evptr, short evtype)
{
	if (func) {
		if (!*evptr) {
#ifdef EV_PERSIST
			evtype |= EV_PERSIST;
#endif
			*evptr = mem_alloc(sizeof_struct_event);
			event_set(*evptr, h, evtype, event_callback, *evptr);
#ifdef HAVE_EVENT_BASE_SET
			if (event_base_set(event_base, *evptr) == -1)
				fatal_exit("ERROR: event_base_set failed: %s at %s:%d, handle %d", strerror(errno), sh_file, sh_line, h);
#endif
		}
		if (event_add(*evptr, NULL) == -1)
			fatal_exit("ERROR: event_add failed: %s at %s:%d, handle %d", strerror(errno), sh_file, sh_line, h);
	} else {
		if (*evptr) {
			if (event_del(*evptr) == -1)
				fatal_exit("ERROR: event_del failed: %s at %s:%d, handle %d", strerror(errno), sh_file, sh_line, h);
		}
	}
}

static void set_events_for_handle(int h)
{
	set_event_for_action(h, threads[h].read_func, &threads[h].read_event, EV_READ);
	set_event_for_action(h, threads[h].write_func, &threads[h].write_event, EV_WRITE);
}

static void set_event_for_timer(struct timer *tm)
{
	struct timeval tv;
	struct event *ev = timer_event(tm);
	timeout_set(ev, timer_callback, tm);
#ifdef HAVE_EVENT_BASE_SET
	if (event_base_set(event_base, ev) == -1)
		fatal_exit("ERROR: event_base_set failed: %s", strerror(errno));
#endif
	tv.tv_sec = tm->interval / 1000;
	tv.tv_usec = (tm->interval % 1000) * 1000;
#if defined(HAVE_LIBEV)
	if (!tm->interval && ev_version_major() < 4) {
		/* libev bug */
		tv.tv_usec = 1;
	}
#endif
	if (timeout_add(ev, &tv) == -1)
		fatal_exit("ERROR: timeout_add failed: %s", strerror(errno));
}

static void enable_libevent(void)
{
	int i;
	struct timer *tm;
	struct list_head *ltm;

	if (disable_libevent)
		return;

#if !defined(NO_FORK_ON_EXIT) && defined(HAVE_KQUEUE) && !defined(HAVE_EVENT_REINIT)
	/* kqueue doesn't work after fork */
	if (!F)
		return;
#endif

#if defined(HAVE_EVENT_CONFIG_SET_FLAG)
	{
		struct event_config *cfg;
		cfg = event_config_new();
		if (!cfg)
			return;
		if (event_config_set_flag(cfg, EVENT_BASE_FLAG_NOLOCK) == -1) {
			event_config_free(cfg);
			return;
		}
		event_base = event_base_new_with_config(cfg);
		event_config_free(cfg);
		if (!event_base)
			return;
	}
#elif defined(HAVE_EVENT_BASE_NEW)
	event_base = event_base_new();
	if (!event_base)
		return;
#elif defined(HAVE_EVENT_BASE_SET)
	event_base = event_init();
	if (!event_base)
		return;
#else
	event_init();
#endif
	event_enabled = 1;

	sh_file = (unsigned char *)__FILE__;
	sh_line = __LINE__;
	for (i = 0; i < w_max; i++)
		set_events_for_handle(i);

	foreach(struct timer, tm, ltm, timers)
		set_event_for_timer(tm);
}

static void terminate_libevent(void)
{
	int i;
	if (event_enabled) {
		for (i = 0; i < n_threads; i++) {
			set_event_for_action(i, NULL, &threads[i].read_event, EV_READ);
			if (threads[i].read_event)
				mem_free(threads[i].read_event);
			set_event_for_action(i, NULL, &threads[i].write_event, EV_WRITE);
			if (threads[i].write_event)
				mem_free(threads[i].write_event);
		}
#ifdef HAVE_EVENT_BASE_FREE
		event_base_free(event_base);
#endif
		event_enabled = 0;
	}
}

static void do_event_loop(int flags)
{
	int e;
#ifdef HAVE_EVENT_BASE_SET
	e = event_base_loop(event_base, flags);
#else
	e = event_loop(flags);
#endif
	if (e == -1)
		fatal_exit("ERROR: event_base_loop failed: %s", strerror(errno));
}

#endif

void add_event_string(unsigned char **s, int *l, struct terminal *term)
{
#ifdef USE_LIBEVENT
	if (!event_enabled)
#endif
		add_to_str(s, l, get_text_translation(TEXT_(T_SELECT_SYSCALL), term));
#ifdef USE_LIBEVENT
	if (!event_enabled)
		add_to_str(s, l, cast_uchar " (");
#ifdef HAVE_LIBEVENT
	add_to_str(s, l, cast_uchar "LibEvent");
#elif defined(HAVE_LIBEV)
	add_to_str(s, l, cast_uchar "LibEv");
#else
	add_to_str(s, l, cast_uchar "LibEvent");
#endif
#ifdef HAVE_EVENT_GET_VERSION
	add_chr_to_str(s, l, ' ');
	{
#if defined(HAVE_LIBEV)
				/* old libev report bogus version */
		if (!casestrcmp(cast_uchar event_get_version(), cast_uchar "EV_VERSION_MAJOR.EV_VERSION_MINOR")) {
			add_num_to_str(s, l, ev_version_major());
			add_chr_to_str(s, l, '.');
			add_num_to_str(s, l, ev_version_minor());
		} else
#endif
		add_to_str(s, l, cast_uchar event_get_version());
	}
#endif
	if (!event_enabled) {
		add_chr_to_str(s, l, ' ');
		add_to_str(s, l, get_text_translation(TEXT_(T_dISABLED), term));
		add_chr_to_str(s, l, ')');
	} else {
#if defined(HAVE_EVENT_BASE_GET_METHOD)
		add_chr_to_str(s, l, ' ');
		add_to_str(s, l, cast_uchar event_base_get_method(event_base));
#elif defined(HAVE_EVENT_GET_METHOD)
		add_chr_to_str(s, l, ' ');
		add_to_str(s, l, cast_uchar event_get_method());
#endif
	}
#endif
}


static uttime last_time;

static void check_timers(void)
{
	uttime interval = get_time() - last_time;
	struct timer *
#ifdef OOPS
		volatile
#endif
		t;		/* volatile because of setjmp */
	struct list_head *
#ifdef OOPS
		volatile	/* volatile because of setjmp */
#endif
		lt;
	foreach(struct timer, t, lt, timers) {
		if (t->interval < interval)
			t->interval = 0;
		else
			t->interval -= interval;
	}
	while (!list_empty(timers)) {
		struct timer *t = list_struct(timers.next, struct timer);
		if (t->interval)
			break;
#ifdef DEBUG_CALLS
		fprintf(stderr, "call: timer %p\n", t->func);
#endif
		pr(t->func(t->data)) break;
#ifdef DEBUG_CALLS
		fprintf(stderr, "timer done\n");
#endif
		kill_timer(t);
		CHK_BH;
	}
	last_time += interval;
}

struct timer *install_timer(uttime t, void (*func)(void *), void *data)
{
	struct timer *tm;
#ifdef USE_LIBEVENT
	{
		unsigned char *q = mem_alloc(sizeof_struct_event + sizeof(struct timer));
		tm = (struct timer *)(q + sizeof_struct_event);
	}
#else
	tm = mem_alloc(sizeof(struct timer));
#endif
	tm->interval = t;
	tm->func = func;
	tm->data = data;
#ifdef USE_LIBEVENT
	if (event_enabled) {
		set_event_for_timer(tm);
		add_to_list(timers, tm);
	} else
#endif
	{
		struct timer *tt;
		struct list_head *ltt;
		foreach(struct timer, tt, ltt, timers) if (tt->interval >= t) break;
		add_before_list_entry(ltt, &tm->list_entry);
	}
	return tm;
}

void kill_timer(struct timer *tm)
{
	del_from_list(tm);
#ifdef USE_LIBEVENT
	if (event_enabled)
		timeout_del(timer_event(tm));
	mem_free(timer_event(tm));
#else
	mem_free(tm);
#endif
}

int verify_handle(int fd)
{
#if defined(USE_POLL) && defined(USE_LIBEVENT)
	if (!event_enabled)
#endif
		if (fd >= (int)FD_SETSIZE)
			return -1;
	return 0;
}

void (*get_handler(int fd, int tp))(void *)
{
	if (fd < 0)
		internal_error("get_handler: handle %d", fd);
	if (fd >= w_max)
		return NULL;
	switch (tp) {
		case H_READ:	return threads[fd].read_func;
		case H_WRITE:	return threads[fd].write_func;
	}
	internal_error("get_handler: bad type %d", tp);
	return NULL;
}

void *get_handler_data(int fd)
{
	if (fd < 0)
		internal_error("get_handler_data: handle %d", fd);
	if (fd >= w_max)
		return NULL;
	return threads[fd].data;
}

void set_handlers_file_line(int fd, void (*read_func)(void *), void (*write_func)(void *), void *data)
{
	if (fd < 0)
		goto invl;
#if defined(DEBUG) && !defined(socket)
	{
		struct stat st;
		int rs;
		EINTRLOOP(rs, fstat(fd, &st));
		if (rs == -1 && errno == EBADF) {
			goto invl;
		}
	}
#endif
#if defined(USE_POLL) && defined(USE_LIBEVENT)
	if (!event_enabled)
#endif
		if (fd >= (int)FD_SETSIZE) {
			fatal_exit("too big handle %d at %s:%d", fd, sh_file, sh_line);
			return;
		}
	if (fd >= n_threads) {
		if ((unsigned)fd > (unsigned)MAXINT / sizeof(struct thread) - 1) overalloc();
		threads = mem_realloc(threads, (fd + 1) * sizeof(struct thread));
		memset(threads + n_threads, 0, (fd + 1 - n_threads) * sizeof(struct thread));
		n_threads = fd + 1;
	}
	if (threads[fd].read_func == read_func && threads[fd].write_func == write_func && threads[fd].data == data)
		return;
	threads[fd].read_func = read_func;
	threads[fd].write_func = write_func;
	threads[fd].data = data;
	if (read_func || write_func) {
		if (fd >= w_max) w_max = fd + 1;
	} else if (fd == w_max - 1) {
		int i;
		for (i = fd - 1; i >= 0; i--)
			if (threads[i].read_func || threads[i].write_func)
				break;
		w_max = i + 1;
	}
#ifdef USE_LIBEVENT
	if (event_enabled) {
		set_events_for_handle(fd);
		return;
	}
#endif
	if (read_func) FD_SET(fd, &w_read);
	else {
		FD_CLR(fd, &w_read);
		FD_CLR(fd, &x_read);
	}
	if (write_func) FD_SET(fd, &w_write);
	else {
		FD_CLR(fd, &w_write);
		FD_CLR(fd, &x_write);
	}
	return;

invl:
	internal_error("invalid set_handlers call at %s:%d: %d, %p, %p, %p", sh_file, sh_line, fd, read_func, write_func, data);
}

void clear_events(int h, int blocking)
{
#if !defined(O_NONBLOCK) && !defined(FIONBIO)
	blocking = 1;
#endif
	while (blocking ? can_read(h) : 1) {
		unsigned char c[64];
		int rd;
		EINTRLOOP(rd, (int)read(h, c, sizeof c));
		if (rd != sizeof c) break;
	}
}

#if defined(NSIG) && NSIG > 32
#define NUM_SIGNALS	NSIG
#else
#define NUM_SIGNALS	32
#endif

#ifndef NO_SIGNAL_HANDLERS

static void clear_events_ptr(void *handle)
{
	clear_events((int)(my_intptr_t)handle, 0);
}


struct signal_handler {
	void (*fn)(void *);
	void *data;
	int critical;
};

static volatile int signal_mask[NUM_SIGNALS];
static volatile struct signal_handler signal_handlers[NUM_SIGNALS];

static pid_t signal_pid;
int signal_pipe[2] = { -1, -1 };

SIGNAL_HANDLER static void got_signal(int sig)
{
	void (*fn)(void *);
	int sv_errno = errno;
		/*fprintf(stderr, "ERROR: signal number: %d\n", sig);*/

#if !defined(HAVE_SIGACTION)
	do_signal(sig, got_signal);
#endif

	/* if we get signal from a forked child, don't do anything */
	if (getpid() != signal_pid) goto ret;

	if (sig >= NUM_SIGNALS || sig < 0) {
		/*error("ERROR: bad signal number: %d", sig);*/
		goto ret;
	}
	fn = signal_handlers[sig].fn;
	if (!fn) goto ret;
	if (signal_handlers[sig].critical) {
		fn(signal_handlers[sig].data);
		goto ret;
	}
	signal_mask[sig] = 1;
	if (can_write(signal_pipe[1])) {
		int wr;
		EINTRLOOP(wr, (int)write(signal_pipe[1], "", 1));
	}
	ret:
	errno = sv_errno;
}

#ifdef HAVE_SIGACTION
static struct sigaction sa_zero;
#endif

#endif

void install_signal_handler(int sig, void (*fn)(void *), void *data, int critical)
{
#if defined(NO_SIGNAL_HANDLERS)
#elif defined(HAVE_SIGACTION)
	int rs;
	struct sigaction sa = sa_zero;
	/*debug("install (%d) -> %p,%d", sig, fn, critical);*/
	if (sig >= NUM_SIGNALS || sig < 0) {
		internal_error("bad signal number: %d", sig);
		return;
	}
	if (!fn) sa.sa_handler = SIG_IGN;
	else sa.sa_handler = (void (*)(int))got_signal;
	sig_fill_set(&sa.sa_mask);
	sa.sa_flags = SA_RESTART;
	if (!fn)
		EINTRLOOP(rs, sigaction(sig, &sa, NULL));
	signal_handlers[sig].fn = fn;
	signal_handlers[sig].data = data;
	signal_handlers[sig].critical = critical;
	if (fn)
		EINTRLOOP(rs, sigaction(sig, &sa, NULL));
#else
	if (!fn) do_signal(sig, SIG_IGN);
	signal_handlers[sig].fn = fn;
	signal_handlers[sig].data = data;
	signal_handlers[sig].critical = critical;
	if (fn) do_signal(sig, got_signal);
#endif
}

void interruptible_signal(int sig, int in)
{
#if defined(HAVE_SIGACTION) && !defined(NO_SIGNAL_HANDLERS)
	struct sigaction sa = sa_zero;
	int rs;
	if (sig >= NUM_SIGNALS || sig < 0) {
		internal_error("bad signal number: %d", sig);
		return;
	}
	if (!signal_handlers[sig].fn) return;
	sa.sa_handler = (void (*)(int))got_signal;
	sig_fill_set(&sa.sa_mask);
	if (!in) sa.sa_flags = SA_RESTART;
	EINTRLOOP(rs, sigaction(sig, &sa, NULL));
#endif
}

static sigset_t sig_old_mask;
static int sig_unblock = 0;

void block_signals(int except1, int except2)
{
	int rs;
	sigset_t mask;
	sig_fill_set(&mask);
#ifdef HAVE_SIGDELSET
	if (except1) sigdelset(&mask, except1);
	if (except2) sigdelset(&mask, except2);
#ifdef SIGILL
	sigdelset(&mask, SIGILL);
#endif
#ifdef SIGABRT
	sigdelset(&mask, SIGABRT);
#endif
#ifdef SIGFPE
	sigdelset(&mask, SIGFPE);
#endif
#ifdef SIGSEGV
	sigdelset(&mask, SIGSEGV);
#endif
#ifdef SIGBUS
	sigdelset(&mask, SIGBUS);
#endif
#else
	if (except1 || except2) return;
#endif
	EINTRLOOP(rs, do_sigprocmask(SIG_BLOCK, &mask, &sig_old_mask));
	if (!rs) sig_unblock = 1;
}

void unblock_signals(void)
{
	int rs;
	if (sig_unblock) {
		EINTRLOOP(rs, do_sigprocmask(SIG_SETMASK, &sig_old_mask, NULL));
		sig_unblock = 0;
	}
}

static int check_signals(void)
{
	int r = 0;
#ifndef NO_SIGNAL_HANDLERS
	volatile int i;	/* volatile because of setjmp */
	for (i = 0; i < NUM_SIGNALS; i++)
		if (signal_mask[i]) {
			signal_mask[i] = 0;
			if (signal_handlers[i].fn) {
#ifdef DEBUG_CALLS
				fprintf(stderr, "call: signal %d -> %p\n", i, signal_handlers[i].fn);
#endif
				pr(signal_handlers[i].fn(signal_handlers[i].data)) {
#ifdef OOPS
					return 1;
#endif
}
#ifdef DEBUG_CALLS
				fprintf(stderr, "signal done\n");
#endif
			}
			CHK_BH;
			r = 1;
		}
#endif
	return r;
}

#ifdef SIGCHLD
static void sigchld(void *p)
{
	pid_t pid;
#ifndef WNOHANG
	EINTRLOOP(pid, wait(NULL));
#else
	do {
		EINTRLOOP(pid, waitpid(-1, NULL, WNOHANG));
	} while (pid > 0);
#endif
}

void set_sigcld(void)
{
	install_signal_handler(SIGCHLD, sigchld, NULL, 1);
}
#else
void set_sigcld(void)
{
}
#endif

#ifdef HAVE_OPENMP

static int num_threads = -1;

int omp_start(void)
{
	int thr;
	if (disable_openmp || num_threads == 1)
		return 1;
	block_signals(0, 0);
	if (num_threads != -1)
		return num_threads;
	omp_set_dynamic(0);
	thr = omp_get_max_threads();
	if (thr > OPENMP_MAX_THREADS)
		thr = OPENMP_MAX_THREADS;
	omp_set_num_threads(thr);
	if (thr > 1) {
#pragma omp parallel shared(thr)
#pragma omp single
			thr = omp_get_num_threads();
		omp_set_num_threads(thr);
	}
	num_threads = thr;
	if (thr == 1)
		unblock_signals();
	return thr;
}

void omp_end(void)
{
	if (disable_openmp || num_threads == 1)
		return;
	unblock_signals();
}

#endif

void reinit_child(void)
{
#if !defined(NO_SIGNAL_HANDLERS)
	signal_pid = getpid();
#endif
#ifdef USE_LIBEVENT
	if (event_enabled) {
#ifdef HAVE_EVENT_REINIT
		if (event_reinit(event_base))
			fatal_exit("ERROR: event_reinit failed: %s", strerror(errno));
#endif
	}
#endif
}

int terminate_loop = 0;

void select_loop(void (*init)(void))
{
#if !defined(USE_LIBEVENT) || !defined(USE_POLL)
	restrict_fds();
#endif

#if !defined(NO_SIGNAL_HANDLERS)
#if defined(HAVE_SIGACTION)
	memset(&sa_zero, 0, sizeof sa_zero);
#endif
	memset((void *)signal_mask, 0, sizeof signal_mask);
	memset((void *)signal_handlers, 0, sizeof signal_handlers);
#endif
	FD_ZERO(&w_read);
	FD_ZERO(&w_write);
	w_max = 0;
	last_time = get_time();
	ignore_signals();
#if !defined(NO_SIGNAL_HANDLERS)
	signal_pid = getpid();
	if (c_pipe(signal_pipe)) {
		fatal_exit("ERROR: can't create pipe for signal handling");
	}
	set_nonblock(signal_pipe[0]);
	set_nonblock(signal_pipe[1]);
	set_handlers(signal_pipe[0], clear_events_ptr, NULL, (void *)(my_intptr_t)signal_pipe[0]);
#endif
	init();
	CHK_BH;

#ifdef USE_LIBEVENT
#ifdef G
	if (!F || !(drv->flags & GD_NO_LIBEVENT))
#endif
	{
		enable_libevent();
	}
#if defined(USE_POLL)
	if (!event_enabled) {
		restrict_fds();
	}
#endif
	if (event_enabled) {
		while (!terminate_loop) {
			check_signals();
			if (!F) {
				do_event_loop(EVLOOP_NONBLOCK);
				check_signals();
				redraw_all_terminals();
			}
			if (terminate_loop) break;
			test_detach_console();
			do_event_loop(EVLOOP_ONCE);
		}
		nopr();
	} else
#endif

	while (!terminate_loop) {
		volatile int n, i;	/* volatile because of setjmp */
		int ww_max;
		struct timeval tv;
		struct timeval *tm = NULL;
		check_signals();
		check_timers();
		if (!F) redraw_all_terminals();
		test_detach_console();
#ifdef OS_BAD_SIGNALS
	/* Cygwin has buggy signals that sometimes don't interrupt select.
	   So don't wait indefinitely in it. */
		tv.tv_sec = 1;
		tv.tv_usec = 0;
		tm = &tv;
#endif
		if (!list_empty(timers)) {
			uttime tt = list_struct(timers.next, struct timer)->interval + 1;
#ifdef OS_BAD_SIGNALS
			if (tt < 1000)
#endif
			{
				tv.tv_sec = tt / 1000 < MAXINT ? (int)(tt / 1000) : MAXINT;
				tv.tv_usec = (tt % 1000) * 1000;
				tm = &tv;
			}
		}
		memcpy(&x_read, &w_read, sizeof(fd_set));
		memcpy(&x_write, &w_write, sizeof(fd_set));
		if (terminate_loop) break;
		/*if (!w_max && list_empty(timers)) {
			break;
		}*/
			/*{
				int i;
				printf("\nR:");
				for (i = 0; i < 256; i++) if (FD_ISSET(i, &x_read)) printf("%d,", i);
				printf("\nW:");
				for (i = 0; i < 256; i++) if (FD_ISSET(i, &x_write)) printf("%d,", i);
				fflush(stdout);
			}*/
#ifdef DEBUG_CALLS
		fprintf(stderr, "select\n");
#endif
		ww_max = w_max;
		if ((n = loop_select(w_max, &x_read, &x_write, NULL, tm)) < 0) {
#ifdef DEBUG_CALLS
			fprintf(stderr, "select intr\n");
#endif
			if (errno != EINTR) {
				fatal_exit("ERROR: select failed: %s", strerror(errno));
			}
			continue;
		}
#ifdef DEBUG_CALLS
		fprintf(stderr, "select done\n");
#endif
		check_signals();
		check_timers();
		/*
		 * EMX has broken select. It should return the total number of
		 * bits set, but instead it returns the number of handles for
		 * which some activity is reported.
		 * Sometimes it returns unusually high values.
		 */
		i = -1;
		while (n > 0 && ++i < ww_max) {
			int k = 0;
			if (FD_ISSET(i, &x_read)) {
				if (threads[i].read_func) {
#ifdef DEBUG_CALLS
					fprintf(stderr, "call: read %d -> %p\n", i, threads[i].read_func);
#endif
					pr(threads[i].read_func(threads[i].data)) continue;
#ifdef DEBUG_CALLS
					fprintf(stderr, "read done\n");
#endif
					CHK_BH;
				}
				k = 1;
			}
			if (FD_ISSET(i, &x_write)) {
				if (threads[i].write_func) {
#ifdef DEBUG_CALLS
					fprintf(stderr, "call: write %d -> %p\n", i, threads[i].write_func);
#endif
					pr(threads[i].write_func(threads[i].data)) continue;
#ifdef DEBUG_CALLS
					fprintf(stderr, "write done\n");
#endif
					CHK_BH;
				}
				k = 1;
			}
			n -= k;
		}
		nopr();
	}
#ifdef DEBUG_CALLS
	fprintf(stderr, "exit loop\n");
#endif
	nopr();
}

void terminate_select(void)
{
#ifdef USE_LIBEVENT
	terminate_libevent();
#endif
	mem_free(threads);
}