make sure to leave XWayland process waitable

On SIGCHLD, check to make sure the terminated process is not the
XWayland process before reaping it, allowing wlroots to waitpid() for it
successfully.

Fixes #177.

1 files changed, 7 insertions, 2 deletions

diff --git a/dwl.c b/dwl.c
index 3f66be4..a14dc5c 100644
--- a/dwl.c
+++ b/dwl.c
@@ -1925,6 +1925,7 @@ setup(void)
 void
 sigchld(int unused)
 {
+	siginfo_t in;
 	/* We should be able to remove this function in favor of a simple
 	 *     signal(SIGCHLD, SIG_IGN);
 	 * but the Xwayland implementation in wlroots currently prevents us from
@@ -1932,8 +1933,12 @@ sigchld(int unused)
 	 */
 	if (signal(SIGCHLD, sigchld) == SIG_ERR)
 		EBARF("can't install SIGCHLD handler");
-	while (0 < waitpid(-1, NULL, WNOHANG))
-		;
+	/* WNOWAIT leaves the child in a waitable state, in case this is the
+	 * XWayland process
+	 */
+	while (!waitid(P_ALL, 0, &in, WEXITED|WNOHANG|WNOWAIT) && in.si_pid
+			&& in.si_pid != xwayland->server->pid)
+		waitpid(in.si_pid, NULL, 0);
 }
 
 void