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, 2 insertions, 4 deletions

diff --git a/ui/gtk/capture_file_dlg.c b/ui/gtk/capture_file_dlg.c
index c1c5d7aac0..5738f232bf 100644
--- a/ui/gtk/capture_file_dlg.c
+++ b/ui/gtk/capture_file_dlg.c
@@ -930,8 +930,7 @@ file_merge_cmd(GtkWidget *w _U_)
       }
 
       if (merge_status != CF_OK) {
-        if (rfcode != NULL)
-          dfilter_free(rfcode);
+        dfilter_free(rfcode);
         g_free(tmpname);
         continue;
       }
@@ -941,8 +940,7 @@ file_merge_cmd(GtkWidget *w _U_)
       /* Try to open the merged capture file. This closes the current file if it succeeds. */
       if (cf_open(&cfile, tmpname, WTAP_TYPE_AUTO, TRUE /* temporary file */, &err) != CF_OK) {
         /* We couldn't open it; fail. */
-        if (rfcode != NULL)
-          dfilter_free(rfcode);
+        dfilter_free(rfcode);
         g_free(tmpname);
         g_string_free(file_name, TRUE);
         g_string_free(display_filter, TRUE);