From e08bd1292288f662eb265461a8c1a9d7501b0445 Mon Sep 17 00:00:00 2001
From: "Devin J. Pohly" <djpohly@gmail.com>
Date: Tue, 29 Mar 2022 15:55:06 -0500
Subject: [PATCH] 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.
---
 dwl.c | 9 +++++++--
 1 file 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