Qt: Add and use qUtf8Printable.

Qt 5.4 introduced qUtf8Printable, a convenience macro for converting
QString to a UTF-8 const char *. Add a compatibility definition and
start using it.

Change-Id: I3cf88611b1ed1a34082cb2ba82394954e2e6c461
Reviewed-on: https://code.wireshark.org/review/24828
Petri-Dish: Gerald Combs <gerald@wireshark.org>
Tested-by: Petri Dish Buildbot
Reviewed-by: Gerald Combs <gerald@wireshark.org>

6 files changed, 46 insertions, 34 deletions

diff --git a/docbook/wsdg_src/WSDG_chapter_userinterface.asciidoc b/docbook/wsdg_src/WSDG_chapter_userinterface.asciidoc
index fd906a3ada..ce2a070a63 100644
--- a/docbook/wsdg_src/WSDG_chapter_userinterface.asciidoc
+++ b/docbook/wsdg_src/WSDG_chapter_userinterface.asciidoc
@@ -163,12 +163,19 @@ it's not strictly required:
 
 ===== Strings
 
-If you're using GLib string functions or plain old C character array idioms in
-Qt-only code you're probably doing something wrong. QStrings are generally
-*much* safer and easier to use. They also make translations easier.
+Wireshark's C code and GLib use UTF-8 encoded character arrays. Qt
+(specifically QString) uses UTF-16. You can convert a `char *` to a
+`QString` using simple assignment. You can convert a `QString` to a
+`const char *` using `qUtf8Printable`.
+
+If you're using GLib string functions or plain old C character array
+idioms in Qt-only code you're probably doing something wrong,
+particularly if you're manually allocating and releasing memory.
+QStrings are generally *much* safer and easier to use. They also make
+translations easier.
 
 If you need to pass strings between Qt and GLib you can use a number
-of convenience routines which  are defined in 'ui/qt/qt_ui_utils.h'.
+of convenience routines which are defined in 'ui/qt/qt_ui_utils.h'.
 
 If you're calling a function that returns wmem-allocated memory it might make
 more sense to add a wrapper function to 'qt_ui_utils' than to call wmem_free in
diff --git a/ui/qt/main_window.cpp b/ui/qt/main_window.cpp
index 2dee41a3e5..83c07d73f1 100644
--- a/ui/qt/main_window.cpp
+++ b/ui/qt/main_window.cpp
@@ -1284,7 +1284,7 @@ void MainWindow::mergeCaptureFile()
         if (merge_dlg.merge(file_name)) {
             gchar *err_msg;
 
-            if (!dfilter_compile(read_filter.toUtf8().constData(), &rfcode, &err_msg)) {
+            if (!dfilter_compile(qUtf8Printable(read_filter), &rfcode, &err_msg)) {
                 /* Not valid. Tell the user, and go back and run the file
                    selection box again once they dismiss the alert. */
                 // Similar to commandline_info.jfilter section in main().
@@ -1455,7 +1455,7 @@ bool MainWindow::saveCaptureFile(capture_file *cf, bool dont_reopen) {
                closes the current file and then opens and reloads the saved file,
                so make a copy and free it later. */
             file_name = cf->filename;
-            status = cf_save_records(cf, file_name.toUtf8().constData(), cf->cd_t, cf->iscompressed,
+            status = cf_save_records(cf, qUtf8Printable(file_name), cf->cd_t, cf->iscompressed,
                                      discard_comments, dont_reopen);
             switch (status) {
 
@@ -1545,14 +1545,14 @@ bool MainWindow::saveAsCaptureFile(capture_file *cf, bool must_support_comments,
 //#ifndef _WIN32
 //        /* If the file exists and it's user-immutable or not writable,
 //                       ask the user whether they want to override that. */
-//        if (!file_target_unwritable_ui(top_level, file_name.toUtf8().constData())) {
+//        if (!file_target_unwritable_ui(top_level, qUtf8Printable(file_name))) {
 //            /* They don't.  Let them try another file name or cancel. */
 //            continue;
 //        }
 //#endif
 
         /* Attempt to save the file */
-        status = cf_save_records(cf, file_name.toUtf8().constData(), file_type, compressed,
+        status = cf_save_records(cf, qUtf8Printable(file_name), file_type, compressed,
                                  discard_comments, dont_reopen);
         switch (status) {
 
@@ -1570,7 +1570,7 @@ bool MainWindow::saveAsCaptureFile(capture_file *cf, bool must_support_comments,
             cf->unsaved_changes = false; //we just saved so we signal that we have no unsaved changes
             updateForUnsavedChanges(); // we update the title bar to remove the *
             /* Add this filename to the list of recent files in the "Recent Files" submenu */
-            add_menu_recent_capture_file(file_name.toUtf8().constData());
+            add_menu_recent_capture_file(qUtf8Printable(file_name));
             return true;
 
         case CF_WRITE_ERROR:
@@ -1647,9 +1647,9 @@ void MainWindow::exportSelectedPackets() {
          * name and the read file name may be relative (if supplied on
          * the command line). From Joerg Mayer.
          */
-        if (files_identical(capture_file_.capFile()->filename, file_name.toUtf8().constData())) {
+        if (files_identical(capture_file_.capFile()->filename, qUtf8Printable(file_name))) {
             QMessageBox msg_box;
-            gchar *display_basename = g_filename_display_basename(file_name.toUtf8().constData());
+            gchar *display_basename = g_filename_display_basename(qUtf8Printable(file_name));
 
             msg_box.setIcon(QMessageBox::Critical);
             msg_box.setText(QString(tr("Unable to export to \"%1\".").arg(display_basename)));
@@ -1668,14 +1668,14 @@ void MainWindow::exportSelectedPackets() {
 //#ifndef _WIN32
 //        /* If the file exists and it's user-immutable or not writable,
 //                       ask the user whether they want to override that. */
-//        if (!file_target_unwritable_ui(top_level, file_name.toUtf8().constData())) {
+//        if (!file_target_unwritable_ui(top_level, qUtf8Printable(file_name))) {
 //            /* They don't.  Let them try another file name or cancel. */
 //            continue;
 //        }
 //#endif
 
         /* Attempt to save the file */
-        status = cf_export_specified_packets(capture_file_.capFile(), file_name.toUtf8().constData(), &range, file_type, compressed);
+        status = cf_export_specified_packets(capture_file_.capFile(), qUtf8Printable(file_name), &range, file_type, compressed);
         switch (status) {
 
         case CF_WRITE_OK:
@@ -1689,7 +1689,7 @@ void MainWindow::exportSelectedPackets() {
             if (discard_comments)
                 packet_list_queue_draw();
             /* Add this filename to the list of recent files in the "Recent Files" submenu */
-            add_menu_recent_capture_file(file_name.toUtf8().constData());
+            add_menu_recent_capture_file(qUtf8Printable(file_name));
             return;
 
         case CF_WRITE_ERROR:
@@ -2858,7 +2858,7 @@ void MainWindow::removeAdditionalToolbar(QString toolbarName)
         AdditionalToolBar *ifToolBar = dynamic_cast<AdditionalToolBar *>(tb);
 
         if (ifToolBar && ifToolBar->menuName().compare(toolbarName)) {
-            GList *entry = g_list_find_custom(recent.gui_additional_toolbars, ifToolBar->menuName().toStdString().c_str(), (GCompareFunc) strcmp);
+            GList *entry = g_list_find_custom(recent.gui_additional_toolbars, qUtf8Printable(ifToolBar->menuName()), (GCompareFunc) strcmp);
             if (entry) {
                 recent.gui_additional_toolbars = g_list_remove(recent.gui_additional_toolbars, entry->data);
             }
diff --git a/ui/qt/main_window_slots.cpp b/ui/qt/main_window_slots.cpp
index 70f76614ed..875561f6b8 100644
--- a/ui/qt/main_window_slots.cpp
+++ b/ui/qt/main_window_slots.cpp
@@ -223,7 +223,7 @@ bool MainWindow::openCaptureFile(QString cf_path, QString read_filter, unsigned
             goto finish;
         }
 
-        if (dfilter_compile(read_filter.toUtf8().constData(), &rfcode, &err_msg)) {
+        if (dfilter_compile(qUtf8Printable(read_filter), &rfcode, &err_msg)) {
             cf_set_rfcode(CaptureFile::globalCapFile(), rfcode);
         } else {
             /* Not valid.  Tell the user, and go back and run the file
@@ -249,7 +249,7 @@ bool MainWindow::openCaptureFile(QString cf_path, QString read_filter, unsigned
 
         /* Try to open the capture file. This closes the current file if it succeeds. */
         CaptureFile::globalCapFile()->window = this;
-        if (cf_open(CaptureFile::globalCapFile(), cf_path.toUtf8().constData(), type, is_tempfile, &err) != CF_OK) {
+        if (cf_open(CaptureFile::globalCapFile(), qUtf8Printable(cf_path), type, is_tempfile, &err) != CF_OK) {
             /* We couldn't open it; don't dismiss the open dialog box,
                just leave it around so that the user can, after they
                dismiss the alert box popped up for the open error,
@@ -514,7 +514,7 @@ void MainWindow::layoutToolbars()
         AdditionalToolBar *iftoolbar = dynamic_cast<AdditionalToolBar *>(bar);
         if (iftoolbar) {
             bool visible = false;
-            if (g_list_find_custom(recent.gui_additional_toolbars, iftoolbar->menuName().toUtf8().constData(), (GCompareFunc) strcmp))
+            if (g_list_find_custom(recent.gui_additional_toolbars, qUtf8Printable(iftoolbar->menuName()), (GCompareFunc) strcmp))
                 visible = true;
 
             iftoolbar->setVisible(visible);
@@ -1909,23 +1909,23 @@ void MainWindow::on_actionFileExportPacketBytes_triggered()
 
         data_p = tvb_get_ptr(capture_file_.capFile()->finfo_selected->ds_tvb, 0, -1) +
                 capture_file_.capFile()->finfo_selected->start;
-        fd = ws_open(file_name.toUtf8().constData(), O_WRONLY|O_CREAT|O_TRUNC|O_BINARY, 0666);
+        fd = ws_open(qUtf8Printable(file_name), O_WRONLY|O_CREAT|O_TRUNC|O_BINARY, 0666);
         if (fd == -1) {
-            open_failure_alert_box(file_name.toUtf8().constData(), errno, TRUE);
+            open_failure_alert_box(qUtf8Printable(file_name), errno, TRUE);
             return;
         }
         if (ws_write(fd, data_p, capture_file_.capFile()->finfo_selected->length) < 0) {
-            write_failure_alert_box(file_name.toUtf8().constData(), errno);
+            write_failure_alert_box(qUtf8Printable(file_name), errno);
             ws_close(fd);
             return;
         }
         if (ws_close(fd) < 0) {
-            write_failure_alert_box(file_name.toUtf8().constData(), errno);
+            write_failure_alert_box(qUtf8Printable(file_name), errno);
             return;
         }
 
         /* Save the directory name for future file dialogs. */
-        wsApp->setLastOpenDir(&file_name);
+        wsApp->setLastOpenDir(file_name);
     }
 }
 
@@ -1982,9 +1982,9 @@ void MainWindow::on_actionFileExportSSLSessionKeys_triggered()
         int fd;
 
         keylist = ssl_export_sessions();
-        fd = ws_open(file_name.toUtf8().constData(), O_WRONLY|O_CREAT|O_TRUNC|O_BINARY, 0666);
+        fd = ws_open(qUtf8Printable(file_name), O_WRONLY|O_CREAT|O_TRUNC|O_BINARY, 0666);
         if (fd == -1) {
-            open_failure_alert_box(file_name.toUtf8().constData(), errno, TRUE);
+            open_failure_alert_box(qUtf8Printable(file_name), errno, TRUE);
             g_free(keylist);
             return;
         }
@@ -1993,19 +1993,19 @@ void MainWindow::on_actionFileExportSSLSessionKeys_triggered()
          * _write().  Presumably this string will be <= 4GiB long....
          */
         if (ws_write(fd, keylist, (unsigned int)strlen(keylist)) < 0) {
-            write_failure_alert_box(file_name.toUtf8().constData(), errno);
+            write_failure_alert_box(qUtf8Printable(file_name), errno);
             ws_close(fd);
             g_free(keylist);
             return;
         }
         if (ws_close(fd) < 0) {
-            write_failure_alert_box(file_name.toUtf8().constData(), errno);
+            write_failure_alert_box(qUtf8Printable(file_name), errno);
             g_free(keylist);
             return;
         }
 
         /* Save the directory name for future file dialogs. */
-        wsApp->setLastOpenDir(&file_name);
+        wsApp->setLastOpenDir(file_name);
         g_free(keylist);
     }
 }
@@ -4135,8 +4135,8 @@ void MainWindow::filterDropped(QString description, QString filter)
     if ( filter.length() == 0 )
         return;
 
-    filter_expression_new(description.toUtf8().constData(),
-            filter.toUtf8().constData(), description.toUtf8().constData(), TRUE);
+    filter_expression_new(qUtf8Printable(description),
+            qUtf8Printable(filter), qUtf8Printable(description), TRUE);
 
     uat_save(uat_get_table_by_name("Display expressions"), &err);
     g_free(err);
diff --git a/ui/qt/utils/qt_ui_utils.h b/ui/qt/utils/qt_ui_utils.h
index 781cf9e1c9..cd5e182d61 100644
--- a/ui/qt/utils/qt_ui_utils.h
+++ b/ui/qt/utils/qt_ui_utils.h
@@ -59,6 +59,11 @@ struct epan_range;
 #define Q_NULLPTR NULL
 #endif
 
+// Introduced in Qt 5.4
+#ifndef qUtf8Printable
+#define qUtf8Printable(str) str.toUtf8().constData()
+#endif
+
 /** Create a glib-compatible copy of a QString.
  *
  * @param q_string A QString.
diff --git a/ui/qt/wireshark_application.cpp b/ui/qt/wireshark_application.cpp
index 4f30f55d6a..af1f8e0f5e 100644
--- a/ui/qt/wireshark_application.cpp
+++ b/ui/qt/wireshark_application.cpp
@@ -220,7 +220,7 @@ extern "C" void menu_recent_file_write_all(FILE *rf) {
         /* get capture filename from the menu item label */
         cf_name = rii.previous()->filename;
         if (cf_name != NULL) {
-            fprintf (rf, RECENT_KEY_CAPTURE_FILE ": %s\n", cf_name.toUtf8().constData());
+            fprintf (rf, RECENT_KEY_CAPTURE_FILE ": %s\n", qUtf8Printable(cf_name));
         }
     }
 }
@@ -281,8 +281,8 @@ QDir WiresharkApplication::lastOpenDir() {
     return QDir(last_open_dir);
 }
 
-void WiresharkApplication::setLastOpenDir(QString *dir_str) {
-    setLastOpenDir(dir_str->toUtf8().constData());
+void WiresharkApplication::setLastOpenDir(QString dir_str) {
+    setLastOpenDir(qUtf8Printable(dir_str));
 }
 
 void WiresharkApplication::helpTopicAction(topic_action_e action)
diff --git a/ui/qt/wireshark_application.h b/ui/qt/wireshark_application.h
index c9d6c9ebba..00e40de958 100644
--- a/ui/qt/wireshark_application.h
+++ b/ui/qt/wireshark_application.h
@@ -109,7 +109,7 @@ public:
     void removeRecentItem(const QString &filename);
     QDir lastOpenDir();
     void setLastOpenDir(const char *dir_name);
-    void setLastOpenDir(QString *dir_str);
+    void setLastOpenDir(QString dir_str);
     void helpTopicAction(topic_action_e action);
     const QFont monospaceFont() const { return mono_font_; }
     void setMonospaceFont(const char *font_string);