From: Christian Kastner <ckk@kvr.at>
Date: Wed, 23 Dec 2015 10:13:55 +0100
Subject: Signal handling issues

Move signal handling away from the obsolete API.

Fix provided by Justin Pryzby <justinpryzby@users.sourceforge.net>, as part of
a larger fix, so it has been split out.

Bug-Debian: https://bugs.debian.org/155109
Forwarded: no
Last-Update: 2015-12-22
Index: cron/cron.c
===================================================================
--- cron.orig/cron.c
+++ cron/cron.c
@@ -256,6 +256,7 @@ cron_sleep() {
 #ifdef USE_SIGCHLD
 static void
 sigchld_handler(int x) {
+	int		save_errno = errno;
 	WAIT_T		waiter;
 	PID_T		pid;
 
@@ -269,10 +270,12 @@ sigchld_handler(int x) {
 		case -1:
 			Debug(DPROC,
 				("[%d] sigchld...no children\n", getpid()))
+			errno = save_errno;
 			return;
 		case 0:
 			Debug(DPROC,
 				("[%d] sigchld...no dead kids\n", getpid()))
+			errno = save_errno;
 			return;
 		default:
 			Debug(DPROC,
@@ -280,6 +283,7 @@ sigchld_handler(int x) {
 				getpid(), pid, WEXITSTATUS(waiter)))
 		}
 	}
+	errno = save_errno;
 }
 #endif /*USE_SIGCHLD*/
 
@@ -287,6 +291,10 @@ sigchld_handler(int x) {
 static void
 sighup_handler(int x) {
 	log_close();
+
+	/* we should use sigaction for proper signal blocking as this
+	   has a race, but... */
+	signal(SIGHUP, sighup_handler);
 }
 
 
Index: cron/popen.c
===================================================================
--- cron.orig/popen.c
+++ cron/popen.c
@@ -180,7 +180,7 @@ cron_pclose(iop)
 	FILE *iop;
 {
 	register int fdes;
-	int omask;
+	sigset_t omask, mask;
 	WAIT_T stat_loc;
 	PID_T pid;
 
@@ -191,10 +191,15 @@ cron_pclose(iop)
 	if (pids == 0 || pids[fdes = fileno(iop)] == 0)
 		return(-1);
 	(void)fclose(iop);
-	omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
-	while ((pid = wait(&stat_loc)) != pids[fdes] && pid != -1)
-		;
-	(void)sigsetmask(omask);
+	sigemptyset(&mask);
+	sigaddset(&mask, SIGQUIT);
+	sigaddset(&mask, SIGINT);
+	sigaddset(&mask, SIGHUP);
+	sigprocmask(SIG_BLOCK, &mask, &omask);
+	pid = waitpid(pids[fdes], &stat_loc, 0);
+	sigprocmask(SIG_SETMASK, &omask, NULL);
 	pids[fdes] = 0;
-	return (pid == -1 ? -1 : WEXITSTATUS(stat_loc));
+	if (pid == -1 || !WIFEXITED(stat_loc))
+		return -1;
+	return WEXITSTATUS(stat_loc);
 }