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Self-pipe timer signal handling

master
Kenny Levinsen 2020-10-18 22:41:22 +02:00
parent f66842c020
commit c7c8dad01d
1 changed files with 54 additions and 23 deletions
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77
main.c
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@ -1,5 +1,6 @@
#include <assert.h> #include <assert.h>
#include <errno.h> #include <errno.h>
#include <fcntl.h>
#include <poll.h> #include <poll.h>
#include <signal.h> #include <signal.h>
#include <stdbool.h> #include <stdbool.h>
@ -505,42 +506,54 @@ static void update_timer(const struct context *ctx, timer_t timer, time_t now) {
timer_settime(timer, TIMER_ABSTIME, &timerspec, NULL); timer_settime(timer, TIMER_ABSTIME, &timerspec, NULL);
} }
static int display_poll(struct wl_display *display, short int events, int timeout) { static int timer_fired = 0;
struct pollfd pfd[1]; static int timer_signal_fds[2];
pfd[0].fd = wl_display_get_fd(display);
pfd[0].events = events;
if (poll(pfd, 1, timeout) == -1) {
return errno == EINTR ? 0 : -1;
}
return 0;
}
static int display_dispatch(struct wl_display *display, int timeout) { static int display_dispatch(struct wl_display *display, int timeout) {
if (wl_display_prepare_read(display) == -1) { if (wl_display_prepare_read(display) == -1) {
return wl_display_dispatch_pending(display); return wl_display_dispatch_pending(display);
} }
int ret; struct pollfd pfd[2];
while (true) { pfd[0].fd = wl_display_get_fd(display);
ret = wl_display_flush(display); pfd[1].fd = timer_signal_fds[0];
if (ret != -1 || errno != EAGAIN) {
break; pfd[0].events = POLLOUT;
while (wl_display_flush(display) == -1) {
if (errno != EAGAIN && errno != EPIPE) {
wl_display_cancel_read(display);
return -1;
} }
if (display_poll(display, POLLOUT, -1) == -1) { // We only poll the wayland fd here
while (poll(pfd, 1, timeout) == -1) {
if (errno != EINTR) {
wl_display_cancel_read(display);
return -1;
}
}
}
pfd[0].events = POLLIN;
pfd[1].events = POLLIN;
while (poll(pfd, 2, timeout) == -1) {
if (errno != EINTR) {
wl_display_cancel_read(display); wl_display_cancel_read(display);
return -1; return -1;
} }
} }
if (ret < 0 && errno != EPIPE) { if (pfd[1].revents & POLLIN) {
wl_display_cancel_read(display); // Empty signal fd
return -1; char garbage[8];
if (read(timer_signal_fds[0], &garbage, sizeof garbage) == -1 && errno != EAGAIN) {
return -1;
}
} }
if (display_poll(display, POLLIN, timeout) == -1) { if ((pfd[0].revents & POLLIN) == 0) {
wl_display_cancel_read(display); wl_display_cancel_read(display);
return -1; return 0;
} }
if (wl_display_read_events(display) == -1) { if (wl_display_read_events(display) == -1) {
@ -550,11 +563,21 @@ static int display_dispatch(struct wl_display *display, int timeout) {
return wl_display_dispatch_pending(display); return wl_display_dispatch_pending(display);
} }
static int timer_fired = 0;
static void timer_signal(int signal) { static void timer_signal(int signal) {
(void)signal; (void)signal;
timer_fired = true; timer_fired = true;
if (write(timer_signal_fds[1], "\0", 1) == -1 && errno != EAGAIN) {
// This is unfortunate.
}
}
static int set_nonblock(int fd) {
int flags;
if ((flags = fcntl(fd, F_GETFL)) == -1 ||
fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1) {
return -1;
}
return 0;
} }
static int setup_timer(struct context *ctx) { static int setup_timer(struct context *ctx) {
@ -562,11 +585,19 @@ static int setup_timer(struct context *ctx) {
.sa_handler = timer_signal, .sa_handler = timer_signal,
.sa_flags = 0, .sa_flags = 0,
}; };
if (pipe(timer_signal_fds) == -1) {
fprintf(stderr, "could not create signal pipe: %s\n", strerror(errno));
return -1;
}
if (set_nonblock(timer_signal_fds[0]) == -1 ||
set_nonblock(timer_signal_fds[1]) == -1) {
fprintf(stderr, "could not set nonblock on signal pipe: %s\n", strerror(errno));
return -1;
}
if (sigaction(SIGALRM, &timer_action, NULL) == -1) { if (sigaction(SIGALRM, &timer_action, NULL) == -1) {
fprintf(stderr, "could not configure alarm handler: %s\n", strerror(errno)); fprintf(stderr, "could not configure alarm handler: %s\n", strerror(errno));
return -1; return -1;
} }
if (timer_create(CLOCK_REALTIME, NULL, &ctx->timer) == -1) { if (timer_create(CLOCK_REALTIME, NULL, &ctx->timer) == -1) {
fprintf(stderr, "could not configure timer: %s\n", strerror(errno)); fprintf(stderr, "could not configure timer: %s\n", strerror(errno));
return -1; return -1;