cssvalue: At cycle detection to color resolving

The following CSS would infloop:

@define-color self @self

as it would infinitely lookup the color named "self" and try to resolve
it. This patch adds detection of such cycles to the resolve function by
keeping a list of currently resolving colors in the cycle_list variable.

gtk/deprecated/gtkgradient.c

@@ -342,7 +342,8 @@ _gtk_gradient_resolve_full (GtkGradient             *gradient,
                                           provider,
                                           _gtk_css_computed_values_get_value (values, GTK_CSS_PROPERTY_COLOR),
                                           GTK_CSS_DEPENDS_ON_COLOR,
-                                          &stop_deps);
+                                          &stop_deps,
+                                          NULL);
       if (val)
         {
           rgba = *_gtk_css_rgba_value_get_rgba (val);

gtk/deprecated/gtksymboliccolor.c

@@ -307,6 +307,7 @@ gtk_symbolic_color_resolve (GtkSymbolicColor   *color,
                                     GTK_STYLE_PROVIDER_PRIVATE (props),
                                     current,
                                     0,
+                                    NULL,
                                     NULL);
   _gtk_css_value_unref (current);
   if (v == NULL)

gtk/gtkcsscolorvalue.c

@@ -140,7 +140,8 @@ _gtk_css_color_value_resolve (GtkCssValue             *color,
                               GtkStyleProviderPrivate *provider,
                               GtkCssValue             *current,
                               GtkCssDependencies       current_deps,
-                              GtkCssDependencies      *dependencies)
+                              GtkCssDependencies      *dependencies,
+                              GSList                  *cycle_list)
 {
   GtkCssDependencies unused;
   GtkCssValue *value;
@@ -160,12 +161,18 @@ _gtk_css_color_value_resolve (GtkCssValue             *color,
     case COLOR_TYPE_NAME:
       {
 	GtkCssValue *named;
+        GSList cycle = { color, cycle_list };
+
+        /* If color exists in cycle_list, we're currently resolving it.
+         * So we've detected a cycle. */
+        if (g_slist_find (cycle_list, color))
+          return NULL;
 
         named = _gtk_style_provider_private_get_color (provider, color->sym_col.name);
 	if (named == NULL)
 	  return NULL;
 
-        value = _gtk_css_color_value_resolve (named, provider, current, current_deps, dependencies);
+        value = _gtk_css_color_value_resolve (named, provider, current, current_deps, dependencies, &cycle);
 	if (value == NULL)
 	  return NULL;
       }
@@ -177,7 +184,7 @@ _gtk_css_color_value_resolve (GtkCssValue             *color,
         GtkHSLA hsla;
 	GdkRGBA shade;
 
-	val = _gtk_css_color_value_resolve (color->sym_col.shade.color, provider, current, current_deps, dependencies);
+	val = _gtk_css_color_value_resolve (color->sym_col.shade.color, provider, current, current_deps, dependencies, cycle_list);
 	if (val == NULL)
 	  return NULL;
 
@@ -199,7 +206,7 @@ _gtk_css_color_value_resolve (GtkCssValue             *color,
 	GtkCssValue *val;
 	GdkRGBA alpha;
 
-	val = _gtk_css_color_value_resolve (color->sym_col.alpha.color, provider, current, current_deps, dependencies);
+	val = _gtk_css_color_value_resolve (color->sym_col.alpha.color, provider, current, current_deps, dependencies, cycle_list);
 	if (val == NULL)
 	  return NULL;
 
@@ -219,13 +226,13 @@ _gtk_css_color_value_resolve (GtkCssValue             *color,
 	GdkRGBA color1, color2, res;
         GtkCssDependencies dep1, dep2;
 
-	val = _gtk_css_color_value_resolve (color->sym_col.mix.color1, provider, current, current_deps, &dep1);
+	val = _gtk_css_color_value_resolve (color->sym_col.mix.color1, provider, current, current_deps, &dep1, cycle_list);
 	if (val == NULL)
 	  return NULL;
 	color1 = *_gtk_css_rgba_value_get_rgba (val);
 	_gtk_css_value_unref (val);
 
-	val = _gtk_css_color_value_resolve (color->sym_col.mix.color2, provider, current, current_deps, &dep2);
+	val = _gtk_css_color_value_resolve (color->sym_col.mix.color2, provider, current, current_deps, &dep2, cycle_list);
 	if (val == NULL)
 	  return NULL;
 	color2 = *_gtk_css_rgba_value_get_rgba (val);
@@ -324,7 +331,8 @@ gtk_css_value_color_compute (GtkCssValue             *value,
                                            provider,
                                            current,
                                            current_deps,
-                                           dependencies);
+                                           dependencies,
+                                           NULL);
 
   if (resolved == NULL)
     return gtk_css_value_color_get_fallback (property_id, provider, values, parent_values);

gtk/gtkcsscolorvalueprivate.h

@@ -47,7 +47,8 @@ GtkCssValue *   _gtk_css_color_value_resolve            (GtkCssValue
                                                          GtkStyleProviderPrivate *provider,
                                                          GtkCssValue             *current,
                                                          GtkCssDependencies       current_deps,
-                                                         GtkCssDependencies      *dependencies);
+                                                         GtkCssDependencies      *dependencies,
+                                                         GSList                  *cycle_list);
 
 
 G_END_DECLS

gtk/gtkcssstylefuncs.c

@@ -234,7 +234,8 @@ rgba_value_compute (GtkStyleProviderPrivate *provider,
                                           provider,
                                           _gtk_css_computed_values_get_value (values, GTK_CSS_PROPERTY_COLOR),
                                           GTK_CSS_DEPENDS_ON_COLOR,
-                                          dependencies);
+                                          dependencies,
+                                          NULL);
       if (val != NULL)
         {
           rgba = *_gtk_css_rgba_value_get_rgba (val);
@@ -323,7 +324,8 @@ color_value_compute (GtkStyleProviderPrivate *provider,
                                           provider,
                                           _gtk_css_computed_values_get_value (values, GTK_CSS_PROPERTY_COLOR),
                                           GTK_CSS_DEPENDS_ON_COLOR,
-                                          dependencies);
+                                          dependencies,
+                                          NULL);
       if (val != NULL)
         {
           const GdkRGBA *rgba = _gtk_css_rgba_value_get_rgba (val);

gtk/gtkstylecontext.c

@@ -2827,7 +2827,8 @@ _gtk_style_context_resolve_color (GtkStyleContext    *context,
                                       GTK_STYLE_PROVIDER_PRIVATE (context->priv->cascade),
                                       _gtk_style_context_peek_property (context, GTK_CSS_PROPERTY_COLOR),
                                       GTK_CSS_DEPENDS_ON_COLOR,
-                                      dependencies);
+                                      dependencies,
+                                      NULL);
   if (val == NULL)
     return FALSE;