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Avoid recursion in gtk_css_node_ensure_style()

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gtk_css_node_ensure_style() recurses over previous siblings to ensure
these have a style before its following sibling.  As seen in
https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/2027 this can
cause us to stack overflow and crash if we have a lot of children.

And even if we don't have *that* many children its still somewhat
bad to have stack depths of the same magnitude as the number of
children, both for performance reasons and debuggability.
This commit is contained in:
Alexander Larsson 2020-06-04 12:10:31 +02:00
parent 36314c3ff7
commit fc823eb610
1 changed files with 33 additions and 12 deletions
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45
gtk/gtkcssnode.c
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@ -949,25 +949,16 @@ gtk_css_node_needs_new_style (GtkCssNode *cssnode)
}
static void
gtk_css_node_ensure_style (GtkCssNode *cssnode,
const GtkCountingBloomFilter *filter,
gint64 current_time)
gtk_css_node_do_ensure_style (GtkCssNode *cssnode,
const GtkCountingBloomFilter *filter,
gint64 current_time)
{
gboolean style_changed;
if (!gtk_css_node_needs_new_style (cssnode))
return;
if (cssnode->parent)
gtk_css_node_ensure_style (cssnode->parent, filter, current_time);
if (cssnode->style_is_invalid)
{
GtkCssStyle *new_style;
if (cssnode->previous_sibling)
gtk_css_node_ensure_style (cssnode->previous_sibling, filter, current_time);
g_clear_pointer (&cssnode->cache, gtk_css_node_style_cache_unref);
new_style = GTK_CSS_NODE_GET_CLASS (cssnode)->update_style (cssnode,
@ -990,6 +981,36 @@ gtk_css_node_ensure_style (GtkCssNode *cssnode,
cssnode->style_is_invalid = FALSE;
}
static void
gtk_css_node_ensure_style (GtkCssNode *cssnode,
const GtkCountingBloomFilter *filter,
gint64 current_time)
{
GtkCssNode *sibling;
if (!gtk_css_node_needs_new_style (cssnode))
return;
if (cssnode->parent)
gtk_css_node_ensure_style (cssnode->parent, filter, current_time);
/* Ensure all siblings before this have a valid style, in order
* starting at the first that needs it. */
sibling = cssnode;
while (sibling->style_is_invalid &&
sibling->previous_sibling != NULL &&
gtk_css_node_needs_new_style (sibling->previous_sibling))
sibling = sibling->previous_sibling;
while (sibling != cssnode)
{
gtk_css_node_do_ensure_style (sibling, filter, current_time);
sibling = sibling->next_sibling;
}
gtk_css_node_do_ensure_style (cssnode, filter, current_time);
}
GtkCssStyle *
gtk_css_node_get_style (GtkCssNode *cssnode)
{