extcap: Add file extension check

The file-open dialog can now be set with file extensions, allowing
 the exclusion of unwanted file types. The syntax is the same
 as for the Qt QFileDialog, e.g.: "Wireshark (*.pcap *.pcapng)"

 Also, the mustexist option is now considered correctly

Change-Id: I9d4efbb5089ce1af640b2a894de07ed79520271e
Reviewed-on: https://code.wireshark.org/review/12913
Reviewed-by: Roland Knall <rknall@gmail.com>
Reviewed-by: Anders Broman <a.broman58@gmail.com>

extcap_parser.c

@@ -339,6 +339,8 @@ extcap_token_sentence *extcap_tokenize_sentence(const gchar *s) {
             tv->param_type = EXTCAP_PARAM_TOOLTIP;
         } else if (g_ascii_strcasecmp(tv->arg, "mustexist") == 0) {
             tv->param_type = EXTCAP_PARAM_FILE_MUSTEXIST;
+        } else if (g_ascii_strcasecmp(tv->arg, "fileext") == 0) {
+            tv->param_type = EXTCAP_PARAM_FILE_EXTENSION;
         } else if (g_ascii_strcasecmp(tv->arg, "name") == 0) {
             tv->param_type = EXTCAP_PARAM_NAME;
         } else if (g_ascii_strcasecmp(tv->arg, "enabled") == 0) {
@@ -477,6 +479,7 @@ extcap_arg *extcap_new_arg(void) {
     r->range_end = NULL;
     r->default_complex = NULL;
     r->fileexists = FALSE;
+    r->fileextension = NULL;
     r->is_required = FALSE;
 
     r->values = NULL;
@@ -503,6 +506,9 @@ void extcap_free_arg(extcap_arg *a) {
     if (a->tooltip != NULL)
         g_free(a->tooltip);
 
+    if (a->fileextension != NULL)
+        g_free(a->fileextension);
+
     if (a->range_start != NULL)
         extcap_free_complex(a->range_start);
 
@@ -594,6 +600,11 @@ extcap_arg *extcap_parse_arg_sentence(GList * args, extcap_token_sentence *s) {
             target_arg->fileexists = (v->value[0] == 't' || v->value[0] == 'T');
         }
 
+        if ((v = extcap_find_param_by_type(s->param_list, EXTCAP_PARAM_FILE_EXTENSION))
+                != NULL) {
+            target_arg->fileextension = g_strdup(v->value);
+        }
+
         if ((v = extcap_find_param_by_type(s->param_list, EXTCAP_PARAM_REQUIRED))
                 != NULL) {
             target_arg->is_required = (v->value[0] == 't' || v->value[0] == 'T');

extcap_parser.h

@@ -67,6 +67,7 @@ typedef enum {
     EXTCAP_PARAM_NAME,
     EXTCAP_PARAM_ENABLED,
     EXTCAP_PARAM_FILE_MUSTEXIST,
+    EXTCAP_PARAM_FILE_EXTENSION,
     EXTCAP_PARAM_PARENT,
     EXTCAP_PARAM_REQUIRED
 } extcap_param_type;
@@ -105,6 +106,8 @@ typedef struct _extcap_arg {
     gchar *call;
     gchar *display;
     gchar *tooltip;
+
+    gchar * fileextension;
     gboolean fileexists;
 
     gboolean is_required;

ui/qt/extcap_argument.cpp

@@ -506,6 +506,14 @@ bool ExtcapArgument::isRequired()
     return FALSE;
 }
 
+bool ExtcapArgument::fileExists()
+{
+    if ( _argument != NULL )
+        return _argument->fileexists;
+
+    return FALSE;
+}
+
 bool ExtcapArgument::isDefault()
 {
     if ( value().compare(defaultValue()) == 0 )

ui/qt/extcap_argument.h

@@ -98,6 +98,8 @@ Q_SIGNALS:
 
 protected:
 
+    bool fileExists();
+
     void setDefault(GHashTable * defaultsList);
 
     ExtcapValueList loadValues(QString parent);

ui/qt/extcap_argument_file.cpp

@@ -71,7 +71,6 @@ QWidget * ExtcapArgumentFileSelection::createEditor(QWidget * parent)
         button->setToolTip(QString().fromUtf8(_argument->tooltip));
     }
 
-
     connect(button, SIGNAL(clicked()), (QObject *)this, SLOT(openFileDialog()));
 
     editLayout->addWidget(textBox);
@@ -98,12 +97,23 @@ void ExtcapArgumentFileSelection::openFileDialog()
     if (QFileInfo(filename).exists())
         workingDir = QFileInfo(filename).dir();
 
+    QString fileExt(tr("Any File (*.*)"));
+    if ( _argument->fileextension != NULL )
+    {
+        QString givenExt = QString().fromUtf8(_argument->fileextension);
+        if ( givenExt.length() != 0 )
+            fileExt.prepend(";;").prepend(givenExt);
+    }
+
     filename = QFileDialog::getOpenFileName((QWidget *)(textBox->parent()),
         QString().fromUtf8(_argument->display) + " " + tr("Open File"),
-        workingDir.absolutePath(), tr("All Files (*.*)"));
+        workingDir.absolutePath(), fileExt);
 
-    if ( QFileInfo(filename).exists() )
+    if ( ! fileExists() || QFileInfo(filename).exists() )
+    {
         textBox->setText(filename);
+        emit valueChanged();
+    }
 }
 
 bool ExtcapArgumentFileSelection::isValid()