From 4cac79efd99b8b68d47e80f4cd8c18f23c376c38 Mon Sep 17 00:00:00 2001
From: Michael Orlitzky <michael@orlitzky.com>
Date: Tue, 17 Oct 2023 11:35:13 -0400
Subject: [PATCH] src/svgtiny_css.c: add user handler function

This function needs to be passed to dom_node_set_user_data() in
set_libcss_node_data(), but we couldn't implement it before our
css_select_handler was defined, because it passes the address of
that select handler to css_libcss_node_data_handler().
---
 src/svgtiny_css.c | 76 ++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 69 insertions(+), 7 deletions(-)

diff --git a/src/svgtiny_css.c b/src/svgtiny_css.c
index e24bd0b..f86e3da 100644
--- a/src/svgtiny_css.c
+++ b/src/svgtiny_css.c
@@ -1858,6 +1858,59 @@ css_error ua_default_for_property(void *pw, uint32_t property,
 }
 
 
+/**
+ * A "user handler" function that we pass to dom_node_set_user_data()
+ * in set_libcss_node_data(). The set_libcss_node_data() documentation
+ * says that if the node (on which data is set) is is deleted or
+ * cloned, or if its ancestors are modified, then we must call
+ * css_libcss_node_data_handler() on the user data. This function
+ * basically just checks to see which DOM event has happened and
+ * calls css_libcss_node_data_handler() when any of those criteria
+ * are met.
+ */
+static void svgtiny_dom_user_data_handler(dom_node_operation operation,
+	dom_string *key, void *data, struct dom_node *src,
+	struct dom_node *dst)
+{
+	/* Technically we should compare "key" against the one used in
+	 * get/set_libcss_node_data(), but at the moment libcss is the
+	 * only user of this libdom feature, and eliding the compare
+	 * saves us the trouble of figuring out how to reference that
+	 * interned_userdata_key from this handler. */
+	UNUSED(key);
+
+	if (data == NULL) {
+		/* No data */
+		return;
+	}
+
+	/* Check the DOM operation, and make the corresponding call to
+	 * css_libcss_node_data_handler(). No error handling is done.
+	 */
+	switch (operation) {
+		case DOM_NODE_CLONED:
+			css_libcss_node_data_handler(&svgtiny_select_handler,
+						CSS_NODE_CLONED,
+						NULL, src, dst, data);
+			break;
+		case DOM_NODE_RENAMED:
+			css_libcss_node_data_handler(&svgtiny_select_handler,
+						CSS_NODE_MODIFIED,
+						NULL, src, NULL, data);
+			break;
+		case DOM_NODE_IMPORTED:
+		case DOM_NODE_ADOPTED:
+		case DOM_NODE_DELETED:
+			css_libcss_node_data_handler(&svgtiny_select_handler,
+						CSS_NODE_DELETED,
+						NULL, src, NULL, data);
+			break;
+		default:
+			/* Our list of cases should have been exhaustive */
+			assert(false);
+	}
+}
+
 /**
  * Store libcss data on a node
  *
@@ -1869,13 +1922,15 @@ css_error ua_default_for_property(void *pw, uint32_t property,
  * \param node               Libdom SVG node on which to store the data
  * \param libcss_node_data   Pointer to the data to store
  *
- * \return Always returns CSS_OK
+ * \return CSS_OK on success, CSS_NOMEM if libdom runs out of memory,
+ *         or CSS_INVALID if any other error occurs
  */
 css_error set_libcss_node_data(void *pw, void *node,
 		void *libcss_node_data)
 {
 	struct svgtiny_parse_state *state;
 	void *old_data;
+	dom_exception err;
 
 	/* A unique "userdata key" (a string) is used to identify this
 	 * data. The fourth parameter (NULL) is a "user handler
@@ -1883,13 +1938,20 @@ css_error set_libcss_node_data(void *pw, void *node,
 	 * it to NULL to avoid a circular reference mess that would
 	 * break the build temporarily. */
 	state = (struct svgtiny_parse_state *)pw;
-	dom_node_set_user_data((dom_node *)node,
-				state->interned_userdata_key,
-				libcss_node_data,
-				NULL,
-				&old_data);
 
-	/* dom_node_set_user_data() always returns DOM_NO_ERR */
+	err = dom_node_set_user_data((dom_node *)node,
+					state->interned_userdata_key,
+					libcss_node_data,
+					NULL,
+					&old_data);
+
+	if (err == DOM_NO_MEM_ERR) {
+		return CSS_NOMEM;
+	}
+	else if (err != DOM_NO_ERR) {
+		return CSS_INVALID;
+	}
+
 	return CSS_OK;
 }
 
-- 
2.49.0