restore SIGCHLD sighandler to default before spawning a program

From sigaction(2):
A child created via fork(2) inherits a copy of its parent's signal dispositions.
During an execve(2), the dispositions of handled signals are reset to the default;
the dispositions of ignored signals are left unchanged.

This refused to start directly some programs from configuring in config.h:

Some reported programs that didn't start were: mpv.

Similar to the commit e81f17d4c196aaed6893fd4beed49991caa3e2a4 from dwm.

1 files changed, 8 insertions, 0 deletions

diff --git a/tabbed.c b/tabbed.c
index 1b61d93..81be5e4 100644
--- a/tabbed.c
+++ b/tabbed.c
@@ -1088,11 +1088,19 @@ setup(void)
 void
 spawn(const Arg *arg)
 {
+	struct sigaction sa;
+
 	if (fork() == 0) {
 		if(dpy)
 			close(ConnectionNumber(dpy));
 
 		setsid();
+
+		sigemptyset(&sa.sa_mask);
+		sa.sa_flags = 0;
+		sa.sa_handler = SIG_DFL;
+		sigaction(SIGCHLD, &sa, NULL);
+
 		if (arg && arg->v) {
 			execvp(((char **)arg->v)[0], (char **)arg->v);
 			fprintf(stderr, "%s: execvp %s", argv0,