Improve signal handler to mimic signalfd better

2 files changed, 69 insertions, 70 deletions

diff --git a/main.c b/main.c
index df1f958..66ed1b4 100644
--- a/main.c
+++ b/main.c
@@ -11,7 +11,6 @@
 #include <stdbool.h>
 #include <getopt.h>
 #include <sys/signalfd.h>
-#include <sys/eventfd.h>
 #include <signal.h>
 #include <systemd/sd-daemon.h>
 #include <cap-ng.h>
@@ -545,10 +544,11 @@ cfg_apply(struct cfg *cfg)
 }
 
 struct signalfd_ev {
-	struct uring_task task;
 	//struct signalfd_siginfo buf;
 	struct cfg *cfg;
-	uint64_t buf;
+	struct uring_task task;
+	struct uring_task_buf tbuf;
+	int pipe[2];
 };
 
 static void
@@ -591,25 +591,63 @@ dump_tree(struct cfg *cfg)
 	debug(DBG_REF, "\n\n");
 }
 
-static struct dns_async *hack_dns = NULL;
-
 static void
 signalfd_read(struct cfg *cfg, struct uring_task *task, int res)
 {
 	struct signalfd_ev *sev = container_of(task, struct signalfd_ev, task);
 	struct server *server, *stmp;
+	static unsigned count = 0;
+	siginfo_t *si;
 
 	assert_return(cfg && task);
 	assert_task_alive(DBG_SIG, task);
 
-	if (res != sizeof(sev->buf))
+	si = (siginfo_t *)task->tbuf->buf;
+	if (res != sizeof(*si))
 		die("error in signalfd (%i)", res);
 
-	if (sev->buf < 1000) {
+	switch (si->si_signo) {
+	case SIGUSR1: {
+		struct dns_async *dns;
+
+		debug(DBG_SIG, "Got a SIGUSR1");
+		if (si->si_code != SI_ASYNCNL || !si->si_ptr) {
+			error("SIGUSR1: unexpected values in siginfo");
+			goto out;
+		}
+
+		dns = si->si_ptr;
+		if (!dns->cb) {
+			error("DNS callback not set");
+			goto out;
+		}
+
+		debug(DBG_DNS, "DNS lookup complete, dns: %p, dns->cb: %p",
+		      dns, dns->cb);
+		dns->cb(dns);
+		break;
+	}
+
+	case SIGUSR2:
+		debug(DBG_SIG, "got a SIGUSR2");
+		dump_tree(cfg);
+		break;
+
+	case SIGTERM:
+		debug(DBG_SIG, "Got a SIGINT/SIGHUP");
 		verbose("got a signal to quit");
 		sd_notifyf(0, "STOPPING=1\nSTATUS=Received signal, exiting");
 		exit(EXIT_SUCCESS);
-	} else if (sev->buf < 10000) {
+		break;
+
+	case SIGINT:
+	case SIGHUP:
+		count++;
+		if (count > 5) {
+			dump_tree(cfghack);
+			exit(EXIT_FAILURE);
+		}
+
 		verbose("got a signal to dump tree");
 		sd_notifyf(0, "STOPPING=1\nSTATUS=Received signal, exiting");
 		dump_tree(cfg);
@@ -622,75 +660,32 @@ signalfd_read(struct cfg *cfg, struct uring_task *task, int res)
 			server_delete(cfg, server);
 		uring_delete(cfg);
 		return;
-	} else {
-		debug(DBG_DNS, "DNS lookup complete, dns: %p, dns->cb: %p",
-		      hack_dns,
-		      hack_dns ? hack_dns->cb : NULL);
 
-		if (!hack_dns || !hack_dns->cb) {
-			error("DNS callback not set");
-			goto out;
-		}
-
-		hack_dns->cb(hack_dns);
+	default:
+		error("got an unknown signal: %i", si->si_signo);
+		break;
 	}
 
 out:
-	uring_read(cfg, &sev->task, &sev->buf, sizeof(sev->buf), signalfd_read);
+	uring_tbuf_read(cfg, &sev->task, signalfd_read);
 }
 
-static int hack_efd = -1;
-
 static void
-hack_handler(int signum, siginfo_t *info, void *ucontext)
+hack_signal_handler(int signum, siginfo_t *si, void *ucontext)
 {
-	uint64_t val;
-	static unsigned count = 0;
+	ssize_t r;
 
-	assert_return(signum > 0 && info);
+	assert_return(signum > 0 && si);
 
-	count++;
-	if (count > 5) {
-		dump_tree(cfghack);
-		exit(EXIT_FAILURE);
-	}
+	r = write(cfghack->sev->pipe[PIPE_WR], si, sizeof(*si));
+	if (r != sizeof(*si))
+		error("write: %zi\n", r);
 
-	switch (signum) {
-	case SIGUSR1:
-		debug(DBG_SIG, "Got a SIGUSR1");
-		if (info->si_code != SI_ASYNCNL || info->si_signo != SIGUSR1 || !info->si_ptr) {
-			debug(DBG_SIG, "unexpected values in siginfo");
-			return;
-		}
-		debug(DBG_SIG, "SIGUSR1 struct dns_async: %p", info->si_ptr);
-		hack_dns = info->si_ptr;
-		val = 10000;
-		break;
-	case SIGINT:
-		debug(DBG_SIG, "Got a SIGINT");
-		val = 1000;
-		break;
-	case SIGHUP:
-		debug(DBG_SIG, "Got a SIGHUP");
-		val = 1000;
-		break;
-	case SIGTERM:
-		debug(DBG_SIG, "Got a SIGTERM");
-		val = 1;
-		break;
-	default:
-		error("Got an unknown sig (%i)", signum);
-		val = 1;
-		break;
-	}
-
-	write(hack_efd, &val, sizeof(val));
 }
 
 static void
 signalfd_init(struct cfg *cfg)
 {
-	int sfd;
 	//sigset_t mask;
 	struct signalfd_ev *sev;
 
@@ -700,6 +695,9 @@ signalfd_init(struct cfg *cfg)
 	if (!sev)
 		die("malloc: %m");
 
+	if (pipe2(sev->pipe, O_CLOEXEC) < 0)
+		die("pipe2: %m");
+
 	/*
 	sigfillset(&mask);
 	if (sigprocmask(SIG_BLOCK, &mask, NULL) < 0)
@@ -712,29 +710,27 @@ signalfd_init(struct cfg *cfg)
 
 	struct sigaction action;
 	sigfillset(&action.sa_mask);
-	action.sa_sigaction = hack_handler;
+	action.sa_sigaction = hack_signal_handler;
 	action.sa_flags = SA_SIGINFO;
 
 	sigaction(SIGINT, &action, NULL);
 	sigaction(SIGHUP, &action, NULL);
 	sigaction(SIGTERM, &action, NULL);
 	sigaction(SIGUSR1, &action, NULL);
+	sigaction(SIGUSR2, &action, NULL);
 
 	action.sa_handler = SIG_IGN;
 	action.sa_flags = 0;
 	sigaction(SIGPIPE, &action, NULL);
 
-	sfd = eventfd(0, EFD_CLOEXEC);
-	if (sfd < 0)
-		die("eventfd: %m");
-
-	debug(DBG_SIG, "using fd %i", sfd);
+	debug(DBG_SIG, "using pipe fds %i -> %i",
+	      sev->pipe[PIPE_WR], sev->pipe[PIPE_RD]);
 	uring_task_init(cfg, &sev->task, "sev", uring_parent(cfg), signalfd_free);
-	uring_task_set_fd(&sev->task, sfd);
+	uring_task_set_fd(&sev->task, sev->pipe[PIPE_RD]);
+	uring_task_set_buf(&sev->task, &sev->tbuf);
 	cfg->sev = sev;
 	sev->cfg = cfg;
-	hack_efd = sfd;
-	uring_read(cfg, &sev->task, &sev->buf, sizeof(sev->buf), signalfd_read);
+	uring_tbuf_read(cfg, &sev->task, signalfd_read);
 }
 
 int
diff --git a/utils.h b/utils.h
index a38602c..3e807bc 100644
--- a/utils.h
+++ b/utils.h
@@ -152,6 +152,9 @@ static inline bool list_empty(struct list_head *list)
 	return list->next == list;
 }
 
+#define PIPE_RD 0
+#define PIPE_WR 1
+
 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
 
 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)