pdf: let launch action to open pdfs from click event

Issue #1333 removed Evince ability to run any command
from pdf 'launch action', while the security concerns
brought up in #1333 were valid, the measure implemented
was maybe too drastic, as there are valid use cases
where launching a pdf is needed.

For instance, the cases described in issue #48, one of
them is the document 'Nissan Patrol Maintenance Manual'
which is comprised of several pdf files, where there is
one acting as index for the others, this index pdf file
uses the launch action to open the other pdf's.

So this commit allows to launch a file from a link
action only when:

- that file is a pdf file.
- the launch action originates from click event,
  to be sure the user requested the action.

Besides, we don't just let the system execute the
file, but because it's a pdf we do it ourselves by
launching a new evince instance (or if that file was
already opened then presenting its window).

Fixes issue #48

libview/ev-view.c

@@ -2183,6 +2183,23 @@ tip_from_link (EvView *view, EvLink *link)
 	return msg;
 }
 
+gboolean
+ev_view_current_event_is_type (EvView *view, GdkEventType type)
+{
+	GdkEvent *event;
+	gboolean ret = FALSE;
+
+	event = gtk_get_current_event ();
+	if (event) {
+		if (event->type == type &&
+		    gdk_event_get_window (event) == gtk_widget_get_window (GTK_WIDGET (view))) {
+			ret = TRUE;
+		}
+		gdk_event_free (event);
+	}
+	return ret;
+}
+
 static void
 ev_view_handle_cursor_over_xy (EvView *view, gint x, gint y)
 {
@@ -2222,13 +2239,11 @@ ev_view_handle_cursor_over_xy (EvView *view, gint x, gint y)
 		EvLinkDest      *dest;
 		EvLinkDestType   type;
 		GtkWidget       *popover, *spinner;
-		GdkEvent        *event;
 		cairo_surface_t *page_surface = NULL;
 		guint            link_dest_page;
 		EvPoint          link_dest_doc;
 		GdkPoint         link_dest_view;
 		gint             device_scale = 1;
-		gboolean         from_motion = FALSE;
 
 		ev_view_set_cursor (view, EV_VIEW_CURSOR_LINK);
 
@@ -2244,16 +2259,8 @@ ev_view_handle_cursor_over_xy (EvView *view, gint x, gint y)
 		if (!dest)
 			return;
 
-		event = gtk_get_current_event ();
-		if (event) {
-			if (event->type == GDK_MOTION_NOTIFY &&
-			    gdk_event_get_window (event) == gtk_widget_get_window (GTK_WIDGET (view))) {
-				from_motion = TRUE;
-			}
-			gdk_event_free (event);
-		}
 		/* Show preview popups only for motion events - Issue #1666 */
-		if (!from_motion)
+		if (!ev_view_current_event_is_type (view, GDK_MOTION_NOTIFY))
 			return;
 
 		type = ev_link_dest_get_dest_type (dest);

libview/ev-view.h

@@ -191,4 +191,7 @@ EV_PUBLIC
 void           ev_view_set_caret_cursor_position    (EvView  *view,
                                                      guint    page,
                                                      guint    offset);
+EV_PUBLIC
+gboolean       ev_view_current_event_is_type        (EvView *view,
+						     GdkEventType type);
 G_END_DECLS

shell/ev-window.c

@@ -6636,12 +6636,88 @@ window_configure_event_cb (EvWindow *window, GdkEventConfigure *event, gpointer
 	return FALSE;
 }
 
-static void
-launch_action (EvWindow *window, EvLinkAction *action)
+static gchar *
+get_uri (const char *filename, EvWindow *window)
 {
-	ev_window_warning_message (window,
-                                   _("Security alert: this document has been prevented from opening the file “%s”"),
-				   ev_link_action_get_filename (action));
+	EvWindowPrivate *priv = GET_PRIVATE (window);
+	gchar *ret;
+
+	if (g_path_is_absolute (filename)) {
+		ret =  g_strdup (filename);
+	} else {
+		GFile *base_file, *file;
+		gchar *dir;
+
+		dir = g_path_get_dirname (priv->uri);
+		base_file = g_file_new_for_uri (dir);
+		file = g_file_resolve_relative_path (base_file, filename);
+		ret = g_file_get_uri (file);
+
+		g_free (dir);
+		g_object_unref (base_file);
+		g_object_unref (file);
+	}
+
+	return ret;
+}
+
+static gboolean
+file_is_pdf (const char *uri)
+{
+	GFile *file;
+	GFileInfo *file_info;
+	gboolean ret = FALSE;
+
+	file = g_file_new_for_uri (uri);
+	file_info = g_file_query_info (file,
+				       G_FILE_ATTRIBUTE_STANDARD_CONTENT_TYPE,
+				       G_FILE_QUERY_INFO_NONE, NULL, NULL);
+	if (file_info != NULL) {
+		const gchar *content_type;
+		content_type = g_file_info_get_content_type (file_info);
+		if (content_type) {
+			gchar *mime_type;
+			mime_type = g_content_type_get_mime_type (content_type);
+			if (g_ascii_strcasecmp (mime_type, "application/pdf") == 0)
+				ret = TRUE;
+			g_free (mime_type);
+		}
+		g_object_unref (file_info);
+	}
+	g_object_unref (file);
+
+	return ret;
+}
+
+static void
+launch_action (EvWindow *ev_window, EvLinkAction *action)
+{
+	EvView *view;
+	EvWindowPrivate *priv = GET_PRIVATE (ev_window);
+	const char *filename = ev_link_action_get_filename (action);
+	gchar *uri;
+
+	if (filename == NULL)
+		return;
+
+	uri = get_uri (filename, ev_window);
+	view = EV_VIEW (priv->view);
+
+	if (!file_is_pdf (uri) || !ev_view_current_event_is_type (view, GDK_BUTTON_RELEASE)) {
+		ev_window_warning_message (ev_window,
+			_("Security alert: this document has been prevented from opening the file “%s”"),
+			filename);
+		return;
+	}
+	/* We are asked to open a PDF file, from a click event, proceed with that - Issue #48
+	 * This spawns new Evince process or if already opened presents its window */
+	ev_application_open_uri_at_dest (EV_APP, uri,
+					 gtk_window_get_screen (GTK_WINDOW (ev_window)),
+					 ev_link_action_get_dest (action),
+					 priv->window_mode, NULL,
+					 gtk_get_current_event_time ());
+	g_free (uri);
+
 }
 
 static void