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/ui/win32/file_dlg_win32.c b/ui/win32/file_dlg_win32.c
index de5fd9c195..84b0174847 100644
--- a/ui/win32/file_dlg_win32.c
+++ b/ui/win32/file_dlg_win32.c
@@ -1323,8 +1323,7 @@ filter_tb_syntax_check(HWND hwnd, TCHAR *filter_text) {
         SendMessage(hwnd, EM_SETBKGNDCOLOR, (WPARAM) 1, COLOR_WINDOW);
         return;
     } else if (dfilter_compile(utf_16to8(strval), &dfp, NULL)) { /* colorize filter string entry */
-        if (dfp != NULL)
-            dfilter_free(dfp);
+        dfilter_free(dfp);
         /* Valid (light green) */
         SendMessage(hwnd, EM_SETBKGNDCOLOR, 0, RGB(0xe4, 0xff, 0xc7)); /* tango_chameleon_1 */
     } else {
@@ -1332,7 +1331,7 @@ filter_tb_syntax_check(HWND hwnd, TCHAR *filter_text) {
         SendMessage(hwnd, EM_SETBKGNDCOLOR, 0, RGB(0xff, 0xcc, 0xcc)); /* tango_scarlet_red_1 */
     }
 
-    if (strval) g_free(strval);
+    g_free(strval);
 }
 
 
@@ -1365,8 +1364,7 @@ open_file_hook_proc(HWND of_hwnd, UINT msg, WPARAM w_param, LPARAM l_param) {
                 case CDN_FILEOK:
                     /* Fetch the read filter */
                     cur_ctrl = GetDlgItem(of_hwnd, EWFD_FILTER_EDIT);
-                    if (g_dfilter_str)
-                        g_free(g_dfilter_str);
+                    g_free(g_dfilter_str);
                     g_dfilter_str = filter_tb_get(cur_ctrl);
 
                     cur_ctrl = GetDlgItem(of_hwnd, EWFD_FORMAT_TYPE);
@@ -2220,8 +2218,7 @@ merge_file_hook_proc(HWND mf_hwnd, UINT msg, WPARAM w_param, LPARAM l_param) {
                 case CDN_FILEOK:
                     /* Fetch the read filter */
                     cur_ctrl = GetDlgItem(mf_hwnd, EWFD_FILTER_EDIT);
-                    if (g_dfilter_str)
-                        g_free(g_dfilter_str);
+                    g_free(g_dfilter_str);
                     g_dfilter_str = filter_tb_get(cur_ctrl);
 
                     cur_ctrl = GetDlgItem(mf_hwnd, EWFD_MERGE_CHRONO_BTN);