From dedbddca4501eb229e0ac5a488c98f5e73260154 Mon Sep 17 00:00:00 2001
From: tuexen <tuexen@FreeBSD.org>
Date: Sat, 7 Apr 2018 21:08:44 +0000
Subject: [PATCH] MFC r328059:

Improve the printing of cmgs when the length is 0. Fix error handling.
---
 usr.bin/truss/syscalls.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/usr.bin/truss/syscalls.c b/usr.bin/truss/syscalls.c
index 2477b22610d..ba030944aa2 100644
--- a/usr.bin/truss/syscalls.c
+++ b/usr.bin/truss/syscalls.c
@@ -1476,10 +1476,15 @@ print_cmsgs(FILE *fp, pid_t pid, bool recv, struct msghdr *msghdr)
 	bool first;
 
 	len = msghdr->msg_controllen;
+	if (len == 0) {
+		fputs("{}", fp);
+		return;
+	}
 	cmsgbuf = calloc(1, len);
 	if (get_struct(pid, msghdr->msg_control, cmsgbuf, len) == -1) {
 		fprintf(fp, "%p", msghdr->msg_control);
 		free(cmsgbuf);
+		return;
 	}
 	msghdr->msg_control = cmsgbuf;
 	first = true;
-- 
2.45.0