Do not call event_del() for signals after fork(), just use sigaction()

directly instead - calling libevent functions after fork() w/o
event_reinit() is a bad idea, even if in this case it was harmless.

cmd-pipe-pane.c

@@ -97,7 +97,7 @@ cmd_pipe_pane_exec(struct cmd *self, struct cmd_ctx *ctx)
 	case 0:
 		/* Child process. */
 		close(pipe_fd[0]);
-		clear_signals();
+		clear_signals(1);
 
 		if (dup2(pipe_fd[1], STDIN_FILENO) == -1)
 			_exit(1);

job.c

@@ -149,7 +149,7 @@ job_run(struct job *job)
 	case -1:
 		return (-1);
 	case 0:		/* child */
-		clear_signals();
+		clear_signals(1);
 
 		environ_push(&global_environ);
 

server.c

@@ -141,7 +141,7 @@ server_start(char *path)
 	/* event_init() was called in our parent, need to reinit. */
 	if (event_reinit(ev_base) != 0)
 		fatal("event_reinit failed");
-	clear_signals();
+	clear_signals(0);
 
 	logfile("server");
 	log_debug("server started, pid %ld", (long) getpid());

signal.c

@@ -62,7 +62,7 @@ set_signals(void(*handler)(int, short, unused void *))
 }
 
 void
-clear_signals(void)
+clear_signals(int after_fork)
 {
 	struct sigaction	sigact;
 
@@ -79,10 +79,25 @@ clear_signals(void)
 	if (sigaction(SIGTSTP, &sigact, NULL) != 0)
 		fatal("sigaction failed");
 
-	event_del(&ev_sighup);
-	event_del(&ev_sigchld);
-	event_del(&ev_sigcont);
-	event_del(&ev_sigterm);
-	event_del(&ev_sigusr1);
-	event_del(&ev_sigwinch);
+	if (after_fork) {
+		if (sigaction(SIGHUP, &sigact, NULL) != 0)
+			fatal("sigaction failed");
+		if (sigaction(SIGCHLD, &sigact, NULL) != 0)
+			fatal("sigaction failed");
+		if (sigaction(SIGCONT, &sigact, NULL) != 0)
+			fatal("sigaction failed");
+		if (sigaction(SIGTERM, &sigact, NULL) != 0)
+			fatal("sigaction failed");
+		if (sigaction(SIGUSR1, &sigact, NULL) != 0)
+			fatal("sigaction failed");
+		if (sigaction(SIGWINCH, &sigact, NULL) != 0)
+			fatal("sigaction failed");
+	} else {
+		event_del(&ev_sighup);
+		event_del(&ev_sigchld);
+		event_del(&ev_sigcont);
+		event_del(&ev_sigterm);
+		event_del(&ev_sigusr1);
+		event_del(&ev_sigwinch);
+	}
 }

tmux.c

@@ -549,7 +549,7 @@ main(int argc, char **argv)
 
 	event_dispatch();
 
-	clear_signals();
+	clear_signals(0);
 
 	client_main();	/* doesn't return */
 }
@@ -636,7 +636,7 @@ main_dispatch(const char *shellcmd)
 			memcpy(&shelldata, imsg.data, sizeof shelldata);
 			shelldata.shell[(sizeof shelldata.shell) - 1] = '\0';
 
-			clear_signals();
+			clear_signals(0);
 
 			shell_exec(shelldata.shell, shellcmd);
 		default:

tmux.h

@@ -1952,8 +1952,8 @@ void		 queue_window_name(struct window *);
 char		*default_window_name(struct window *);
 
 /* signal.c */
-void set_signals(void(*handler)(int, short, unused void *));
-void clear_signals(void);
+void set_signals(void(*)(int, short, void *));
+void clear_signals(int);
 
 /* session.c */
 extern struct sessions sessions;

window.c

@@ -574,7 +574,7 @@ window_pane_spawn(struct window_pane *wp, const char *cmd, const char *shell,
 
 		environ_push(env);
 
-		clear_signals();
+		clear_signals(1);
 		log_close();
 
 		if (*wp->cmd != '\0') {