Add a routine to format error messages with an errno-based message at the end.

That routine will use strerror_s() or strerror_r() if available, in a
fashion that's thread-safe.  Otherwise, it falls back on
pcap_strerror().

Use it in both libpcap and rpcapd.

Given that we check for errors in strerror_r(), hopefully this will
squelch warnings with newer version of GCC and GNU libc; whilst the
macOS (and other BSD-flavored?) strerror_r() always fills in a message,
that's not required by the Single UNIX Specification, as far as I can
tell, so we apparently really *do* need to check for errors.

1 files changed, 2 insertions, 2 deletions

diff --git a/pcap-tc.c b/pcap-tc.c
index 67584efa..194cdf13 100644
--- a/pcap-tc.c
+++ b/pcap-tc.c
@@ -1130,8 +1130,8 @@ TcSetFilter(pcap_t *p, struct bpf_program *fp)
 	/* Install a user level filter */
 	if (install_bpf_program(p, fp) < 0)
 	{
-		pcap_snprintf(p->errbuf, sizeof(p->errbuf),
-			"setfilter, unable to install the filter: %s", pcap_strerror(errno));
+		pcap_fmt_errmsg_for_errno(p->errbuf, sizeof(p->errbuf),
+		    errno, "setfilter, unable to install the filter");
 		return -1;
 	}