[iptables PATCH v2 1/2] nft: Fix command name in ip6tables error message

[Phil Sutter <phil@nwl.cc>]

Upon errors, ip6tables-nft would prefix its error messages with
'iptables:' instead of 'ip6tables:'. Turns out the command name was
hard-coded, use 'progname' variable instead.
While being at it, merge the two mostly identical fprintf() calls into
one.

Signed-off-by: Phil Sutter <phil@nwl.cc>
---
Changes since v1:
- Added this fix. Related test ignored the prefix value, so this went
  unnoticed.
---
 iptables/xtables-standalone.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/iptables/xtables-standalone.c b/iptables/xtables-standalone.c
index dd6fb7919d2e1..7b71db62f1ea6 100644
--- a/iptables/xtables-standalone.c
+++ b/iptables/xtables-standalone.c
@@ -75,14 +75,10 @@ xtables_main(int family, const char *progname, int argc, char *argv[])
 	xtables_fini();
 
 	if (!ret) {
-		if (errno == EINVAL) {
-			fprintf(stderr, "iptables: %s. "
-					"Run `dmesg' for more information.\n",
-				nft_strerror(errno));
-		} else {
-			fprintf(stderr, "iptables: %s.\n",
-				nft_strerror(errno));
-		}
+		fprintf(stderr, "%s: %s.%s\n", progname, nft_strerror(errno),
+			(errno == EINVAL ?
+			 " Run `dmesg' for more information." : ""));
+
 		if (errno == EAGAIN)
 			exit(RESOURCE_PROBLEM);
 	}
-- 
2.27.0