Remove SIGCHLD signal handler

The purpose is to make child_wait() reliable. The handler is meant for
the notify main thread, but signal handlers are shared by all threads.
In the calcurse main thread and the periodic save thread (hooks) the
handler and child_wait() will compete (if the signal handler kicks in
first, the waitpid() call in child_wait() will fail with errno ECHILD).

All child processes in the main thread, the notify thread, the periodic
save thread and the notify demon are explicitly waited for.

Signed-off-by: Lars Henriksen <LarsHenriksen@get2net.dk>
Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>

4 files changed, 17 insertions, 19 deletions

diff --git a/src/dmon.c b/src/dmon.c
index f9bbfd2..e61caf5 100644
--- a/src/dmon.c
+++ b/src/dmon.c
@@ -34,7 +34,7 @@
  *
  */
 
-#include <sys/types.h>
+#include <sys/wait.h>
 #include <sys/stat.h>
 #include <unistd.h>
 #include <paths.h>
@@ -143,8 +143,7 @@ static unsigned daemonize(int status)
 	    || !sigs_set_hdlr(SIGTERM, dmon_sigs_hdlr)
 	    || !sigs_set_hdlr(SIGALRM, dmon_sigs_hdlr)
 	    || !sigs_set_hdlr(SIGQUIT, dmon_sigs_hdlr)
-	    || !sigs_set_hdlr(SIGUSR1, dmon_sigs_hdlr)
-	    || !sigs_set_hdlr(SIGCHLD, SIG_IGN))
+	    || !sigs_set_hdlr(SIGUSR1, dmon_sigs_hdlr))
 		return 0;
 
 	return 1;
@@ -203,6 +202,9 @@ void dmon_start(int parent_exit_status)
 			 DMON_SLEEP_TIME);
 		psleep(DMON_SLEEP_TIME);
 		DMON_LOG(_("awakened at %s\n"), nowstr());
+		/* Reap the user-defined notifications. */
+		while (waitpid(0, NULL, WNOHANG) > 0)
+			;
 	}
 }
 
diff --git a/src/notify.c b/src/notify.c
index a24beb2..036af0f 100644
--- a/src/notify.c
+++ b/src/notify.c
@@ -34,6 +34,7 @@
  *
  */
 
+#include <sys/wait.h>
 #include <time.h>
 #include <stdlib.h>
 #include <string.h>
@@ -358,6 +359,9 @@ static void *notify_main_thread(void *arg)
 		pthread_mutex_unlock(&notify.mutex);
 		notify_update_bar();
 		psleep(thread_sleep);
+		/* Reap the user-defined notifications. */
+		while (waitpid(0, NULL, WNOHANG) > 0)
+			;
 		elapse += thread_sleep;
 		if (elapse >= check_app) {
 			elapse = 0;
diff --git a/src/sigs.c b/src/sigs.c
index 02457ae..fab4498 100644
--- a/src/sigs.c
+++ b/src/sigs.c
@@ -68,27 +68,18 @@
 
 /*
  * General signal handling routine.
- * Catch return values from children (user-defined notification commands).
- * This is needed to avoid zombie processes running on system.
- * Also catch CTRL-C (SIGINT), and SIGWINCH to resize screen automatically.
+ * Catch SIGWINCH to resize screen automatically.
  */
 static void generic_hdlr(int sig)
 {
 	switch (sig) {
-	case SIGCHLD:
-		while (waitpid(WAIT_MYPGRP, NULL, WNOHANG) > 0) ;
-		break;
 	case SIGWINCH:
 		resize = 1;
 		clearok(curscr, TRUE);
 		ungetch(KEY_RESIZE);
 		break;
 	case SIGTERM:
-		if (unlink(path_cpid) != 0) {
-			EXIT(_("Could not remove calcurse lock file: %s\n"),
-			     strerror(errno));
-		}
-		exit(EXIT_SUCCESS);
+		exit_calcurse(EXIT_SUCCESS);
 		break;
 	case SIGUSR1:
 		want_reload = 1;
@@ -117,12 +108,11 @@ unsigned sigs_set_hdlr(int sig, void (*handler) (int))
 /* Signal handling init. */
 void sigs_init()
 {
-	if (!sigs_set_hdlr(SIGCHLD, generic_hdlr)
-	    || !sigs_set_hdlr(SIGWINCH, generic_hdlr)
+	if (!sigs_set_hdlr(SIGWINCH, generic_hdlr)
 	    || !sigs_set_hdlr(SIGTERM, generic_hdlr)
 	    || !sigs_set_hdlr(SIGUSR1, generic_hdlr)
 	    || !sigs_set_hdlr(SIGINT, SIG_IGN))
-		exit_calcurse(1);
+		exit_calcurse(EXIT_FAILURE);
 }
 
 /* Ignore SIGWINCH and SIGTERM signals. */
diff --git a/src/utils.c b/src/utils.c
index 0a98ce0..2d2f615 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -1425,8 +1425,10 @@ int child_wait(int *pfdin, int *pfdout, int pid)
 	if (pfdout)
 		close(*pfdout);
 
-	waitpid(pid, &stat, 0);
-	return stat;
+	if (waitpid(pid, &stat, 0) == pid)
+		return stat;
+	else
+		return -1;
 }
 
 /* Display "Press any key to continue..." and wait for a key press. */