commit 07ce96a3a0f4a650933f5f586082cbf2064ea2c1
from: Jochen Sprickerhof <dwm@jochen.sprickerhof.de>
via: Roberto E. Vargas Caballero <k0ga@shike2.com>
date: Mon May  4 08:57:40 2015 UTC

Fix sigchld

Only wait for termination of the shell.

commit - 190b94c7a2a7bb2f5d55cbb6eb1779fd042c6467
commit + 07ce96a3a0f4a650933f5f586082cbf2064ea2c1
blob - d954288508f8432fae0efd78749e467931973bea
blob + 300cab631d76ead7242c23e3a0b06162427bd19c
--- st.c
+++ st.c
@@ -1238,10 +1238,14 @@ execsh(void) {
 void
 sigchld(int a) {
 	int stat, ret;
+	pid_t p;
 
-	if(waitpid(pid, &stat, 0) < 0)
+	if((p = waitpid(pid, &stat, WNOHANG)) < 0)
 		die("Waiting for pid %hd failed: %s\n", pid, strerror(errno));
 
+	if(pid != p)
+		return;
+
 	ret = WIFEXITED(stat) ? WEXITSTATUS(stat) : EXIT_FAILURE;
 	if (ret != EXIT_SUCCESS)
 		die("child finished with error '%d'\n", stat);