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, 1 insertions, 3 deletions

diff --git a/epan/tap.c b/epan/tap.c
index 4760a3b302..b942383a3c 100644
--- a/epan/tap.c
+++ b/epan/tap.c
@@ -516,9 +516,7 @@ free_tap_listener(volatile tap_listener_t *tl)
 {
 	if(!tl)
 		return;
-	if(tl->code){
-		dfilter_free(tl->code);
-	}
+	dfilter_free(tl->code);
 	g_free(tl->fstring);
 DIAG_OFF(cast-qual)
 	g_free((gpointer)tl);