Coverity found those:

- Initalize neighbor since we don't touch all members when setting it up.
- In fmt_flags() increase the flagstr to be able to hold all flags even
though some flags are mutually exclusive but lets play it safe.
- Error out if multiple mrt files are provided. It makes no sense to set
  more than one file.

Fixes for CID 492333, 492337 and 492338
-- 
:wq Claudio

Index: bgpctl.c
===================================================================
RCS file: /cvs/src/usr.sbin/bgpctl/bgpctl.c,v
diff -u -p -r1.318 bgpctl.c
--- bgpctl.c	4 Nov 2025 10:59:17 -0000	1.318
+++ bgpctl.c	4 Nov 2025 15:11:31 -0000
@@ -86,7 +86,7 @@ main(int argc, char *argv[])
 	struct imsg		 imsg;
 	struct network_config	 net;
 	struct parse_result	*res;
-	struct ctl_neighbor	 neighbor;
+	struct ctl_neighbor	 neighbor = { 0 };
 	struct ctl_show_rib_request	ribreq;
 	struct flowspec		*f;
 	char			*sockname;
@@ -747,7 +747,7 @@ const char *
 fmt_flags(uint32_t flags, int sum)
 {
 	static char buf[80];
-	char	 flagstr[5];
+	char	 flagstr[12];
 	char	*p = flagstr;
 
 	if (sum) {
Index: parser.c
===================================================================
RCS file: /cvs/src/usr.sbin/bgpctl/parser.c,v
diff -u -p -r1.138 parser.c
--- parser.c	10 Mar 2025 14:08:25 -0000	1.138
+++ parser.c	4 Nov 2025 15:15:55 -0000
@@ -489,6 +489,7 @@ parse(int argc, char *argv[])
 
 	memset(&res, 0, sizeof(res));
 	res.rtableid = getrtable();
+	res.mrtfd = -1;
 	TAILQ_INIT(&res.set);
 
 	while (argc >= 0) {
@@ -801,6 +802,8 @@ match_token(int argc, char *argv[], cons
 			break;
 		case FILENAME:
 			if (word != NULL && wordlen > 0) {
+				if (res.mrtfd != -1)
+					errx(1, "mrt file already set");
 				if ((res.mrtfd = open(word, O_RDONLY)) == -1) {
 					/*
 					 * ignore error if path has no / and