New helper to add markers

The add_marker() function is used to create a new marker and add it at
the right spot to the relevant marker list. Use it in the
add_string_markers() helper (which gets slightly quicker by it).

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

treesource.c

@@ -139,26 +139,48 @@ static const char *delim_end[] = {
 	[TYPE_STRING] = "",
 };
 
+/*
+ * The invariants in the marker list are:
+ *  - offsets are non-strictly monotonically increasing
+ *  - for a single offset there is at most one type marker
+ *  - for a single offset that has both a type marker and non-type markers, the
+ *    type marker appears before the others.
+ */
+static struct marker **add_marker(struct marker **mi,
+				  enum markertype type, unsigned int offset, char *ref)
+{
+	struct marker *nm;
+
+	while (*mi && (*mi)->offset < offset)
+		mi = &(*mi)->next;
+
+	if (*mi && (*mi)->offset == offset && is_type_marker((*mi)->type)) {
+		if (is_type_marker(type))
+			return mi;
+		mi = &(*mi)->next;
+	}
+
+	if (*mi && (*mi)->offset == offset && type == (*mi)->type)
+		return mi;
+
+	nm = xmalloc(sizeof(*nm));
+	nm->type = type;
+	nm->offset = offset;
+	nm->ref = ref;
+	nm->next = *mi;
+	*mi = nm;
+
+	return &nm->next;
+}
+
 static void add_string_markers(struct property *prop)
 {
 	int l, len = prop->val.len;
 	const char *p = prop->val.val;
+	struct marker **mi = &prop->val.markers;
 
-	for (l = strlen(p) + 1; l < len; l += strlen(p + l) + 1) {
-		struct marker *m, **nextp;
-
-		m = xmalloc(sizeof(*m));
-		m->offset = l;
-		m->type = TYPE_STRING;
-		m->ref = NULL;
-		m->next = NULL;
-
-		/* Find the end of the markerlist */
-		nextp = &prop->val.markers;
-		while (*nextp)
-			nextp = &((*nextp)->next);
-		*nextp = m;
-	}
+	for (l = strlen(p) + 1; l < len; l += strlen(p + l) + 1)
+		mi = add_marker(mi, TYPE_STRING, l, NULL);
 }
 
 static enum markertype guess_value_type(struct property *prop)