Remove superfluous null-checks before strdup/free

NULL checks were removed for following free functions:

- g_free "If mem is NULL it simply returns"
  https://developer.gnome.org/glib/stable/glib-Memory-Allocation.html#g-free

- g_slist_free(_full)? "NULL is considered to be the empty list"
  https://developer.gnome.org/glib/stable/glib-Singly-Linked-Lists.html

- g_strfreev "If str_array is NULL, this function simply returns."
  https://developer.gnome.org/glib/stable/glib-String-Utility-Functions.html#g-strfreev

- g_slice_free "If mem is NULL, this macro does nothing."
  https://developer.gnome.org/glib/stable/glib-Memory-Slices.html#g-slice-free

- g_match_info_free "not NULL... otherwise does nothing"
  https://developer.gnome.org/glib/stable/glib-Perl-compatible-regular-expressions.html#g-match-info-free

- dfilter_free defined in Wireshark code. Returns early when passed NULL
  epan/dfilter/dfilter.c

They were also removed around calls to g_strdup where applicable:

- g_strdup "If str is NULL it returns NULL."
  https://developer.gnome.org/glib/stable/glib-String-Utility-Functions.html#g-strdup

Change-Id: Ie80c2db89bef531edc3aed7b7c9f654e1d654d04
Reviewed-on: https://code.wireshark.org/review/23406
Petri-Dish: Roland Knall <rknall@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: João Valverde <j@v6e.pt>

1 files changed, 4 insertions, 7 deletions

diff --git a/epan/dissectors/asn1/kerberos/packet-kerberos-template.c b/epan/dissectors/asn1/kerberos/packet-kerberos-template.c
index 6ce598896f..4412fb1440 100644
--- a/epan/dissectors/asn1/kerberos/packet-kerberos-template.c
+++ b/epan/dissectors/asn1/kerberos/packet-kerberos-template.c
@@ -251,10 +251,7 @@ read_keytab_file_from_preferences(void)
 		return;
 	}
 
-	if (last_keytab != NULL) {
-		g_free(last_keytab);
-		last_keytab = NULL;
-	}
+	g_free(last_keytab);
 	last_keytab = g_strdup(keytab_filename);
 
 	read_keytab_file(last_keytab);
@@ -620,9 +617,9 @@ clear_keytab(void) {
 	for(ske = service_key_list; ske != NULL; ske = g_slist_next(ske)){
 		sk = (service_key_t *) ske->data;
 		if (sk) {
-					g_free(sk->contents);
-					g_free(sk);
-				}
+			g_free(sk->contents);
+			g_free(sk);
+		}
 	}
 	g_slist_free(service_key_list);
 	service_key_list = NULL;