From fdb905e20f6b3378b1905d7e7cacf807fc95867d Mon Sep 17 00:00:00 2001
From: Baptiste Daroussin <bapt@FreeBSD.org>
Date: Mon, 9 Sep 2019 15:24:48 +0000
Subject: [PATCH] m4: import patch from OpenBSD

Use waitpid()/EINTR idiom for the specific pid, rather than generic wait()

Patch by: deraadt@

Obtained from:	OpenBSD
---
 usr.bin/m4/gnum4.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/usr.bin/m4/gnum4.c b/usr.bin/m4/gnum4.c
index 905337151678..f09033786161 100644
--- a/usr.bin/m4/gnum4.c
+++ b/usr.bin/m4/gnum4.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: gnum4.c,v 1.51 2017/06/15 13:48:42 bcallah Exp $ */
+/* $OpenBSD: gnum4.c,v 1.52 2017/08/21 21:41:13 deraadt Exp $ */
 
 /*-
  * SPDX-License-Identifier: BSD-2-Clause
@@ -634,7 +634,7 @@ void
 doesyscmd(const char *cmd)
 {
 	int p[2];
-	pid_t pid, cpid;
+	pid_t cpid;
 	char *argv[4];
 	int cc;
 	int status;
@@ -672,8 +672,10 @@ doesyscmd(const char *cmd)
 		} while (cc > 0 || (cc == -1 && errno == EINTR));
 
 		(void) close(p[0]);
-		while ((pid = wait(&status)) != cpid && pid >= 0)
-			continue;
+		while (waitpid(cpid, &status, 0) == -1) {
+			if (errno != EINTR)
+				break;
+		}
 		pbstr(getstring());
 	}
 }