dfilter: Cache stnode_tostr()

This avoids having to save/free the pointer for each tostr()
invocation (or leak memory).

epan/dfilter/semcheck.c

@@ -611,7 +611,6 @@ check_drange_sanity(dfwork_t *dfw, stnode_t *st)
 	header_field_info	*hfinfo1;
 	ftenum_t		ftype1;
 	struct check_drange_sanity_args	args;
-	char *s;
 
 	entity1 = sttype_range_entity(st);
 	if (entity1 && stnode_type_id(entity1) == STTYPE_FIELD) {
@@ -638,10 +637,8 @@ check_drange_sanity(dfwork_t *dfw, stnode_t *st)
 		/* Should this be rejected instead? */
 		check_drange_sanity(dfw, entity1);
 	} else if (entity1) {
-		s = stnode_tostr(entity1);
 		dfilter_fail(dfw, "Range is not supported for entity %s of type %s",
-					s, stnode_type_name(entity1));
-		g_free(s);
+					stnode_tostr(entity1), stnode_type_name(entity1));
 		THROW(TypeError);
 	} else {
 		dfilter_fail(dfw, "Range is not supported, details: " G_STRLOC " entity: NULL");

epan/dfilter/sttype-function.c

@@ -57,16 +57,13 @@ function_tostr(const void *data)
 	const df_func_def_t *def = stfuncrec->funcdef;
 	GSList *params = stfuncrec->params;
 	GString *repr = g_string_new("");
-	char *s;
 
 	ws_assert(def);
 
 	g_string_printf(repr, "%s(", def->name);
 	while (params != NULL) {
 		ws_assert(params->data);
-		s = stnode_tostr(params->data);
-		g_string_append(repr, s);
-		g_free(s);
+		g_string_append(repr, stnode_tostr(params->data));
 		params = params->next;
 		if (params != NULL) {
 			g_string_append(repr, ", ");

epan/dfilter/sttype-range.c

@@ -77,13 +77,12 @@ range_tostr(const void *data)
 {
 	range_t	*range = (range_t*)data;
 	ws_assert_magic(range, RANGE_MAGIC);
-	char *repr, *entity_str, *drange_str;
+	char *repr, *drange_str;
 
-	entity_str = stnode_tostr(range->entity);
 	drange_str = drange_tostr(range->drange);
-
-	repr = g_strdup_printf("%s[%s]", entity_str, drange_str);
-	g_free(entity_str);
+	repr = g_strdup_printf("%s[%s]",
+			stnode_tostr(range->entity),
+			drange_str);
 	g_free(drange_str);
 
 	return repr;

epan/dfilter/sttype-set.c

@@ -47,13 +47,10 @@ sttype_set_tostr(const void *data)
 	GSList* nodelist = (GSList *)data;
 	stnode_t *lower, *upper;
 	GString *repr = g_string_new("");
-	char *str;
 
 	while (nodelist) {
 		lower = nodelist->data;
-		str = stnode_tostr(lower);
-		g_string_append(repr, str);
-		g_free(str);
+		g_string_append(repr, stnode_tostr(lower));
 
 		/* Set elements are always in pairs; upper may be null. */
 		nodelist = g_slist_next(nodelist);
@@ -61,9 +58,7 @@ sttype_set_tostr(const void *data)
 		upper = nodelist->data;
 		if (upper != NULL) {
 			g_string_append(repr, "..");
-			str = stnode_tostr(upper);
-			g_string_append(repr, str);
-			g_free(str);
+			g_string_append(repr, stnode_tostr(upper));
 		}
 
 		nodelist = g_slist_next(nodelist);

epan/dfilter/syntax-tree.c

@@ -88,6 +88,8 @@ _node_clear(stnode_t *node)
 	node->type = NULL;
 	node->flags = 0;
 	node->data = NULL;
+	g_free(node->repr);
+	node->repr = NULL;
 }
 
 void
@@ -107,6 +109,7 @@ _node_init(stnode_t *node, sttype_id_t type_id, gpointer data)
 	ws_assert(!node->type);
 	ws_assert(!node->data);
 	node->flags = 0;
+	node->repr = NULL;
 
 	if (type_id == STTYPE_UNINITIALIZED) {
 		node->type = NULL;
@@ -253,20 +256,24 @@ stnode_set_inside_parens(stnode_t *node, gboolean inside)
 	}
 }
 
-char *
+const char *
 stnode_tostr(stnode_t *node)
 {
-	if (node->type->func_tostr == NULL)
-		return g_strdup("<FIXME>");
+	if (node->repr != NULL)
+		return node->repr;
 
-	return node->type->func_tostr(node->data);
+	if (node->type->func_tostr == NULL)
+		node->repr = g_strdup("<FIXME>");
+	else
+		node->repr = node->type->func_tostr(node->data);
+
+	return node->repr;
 }
 
 static char *
 sprint_node(stnode_t *node)
 {
 	wmem_strbuf_t *buf = wmem_strbuf_new(NULL, NULL);
-	char *s;
 
 	wmem_strbuf_append_printf(buf, "stnode <%p> = {\n", (void *)node);
 	wmem_strbuf_append_printf(buf, "\tmagic = %"PRIx32"\n", node->magic);
@@ -274,9 +281,7 @@ sprint_node(stnode_t *node)
 	wmem_strbuf_append_printf(buf,
 			"\tflags = %"PRIx16" (inside_parens = %s)\n",
 			node->flags, true_or_false(stnode_inside_parens(node)));
-	s = stnode_tostr(node);
-	wmem_strbuf_append_printf(buf, "\tdata = %s<%s>\n", stnode_type_name(node), s);
-	g_free(s);
+	wmem_strbuf_append_printf(buf, "\tdata = %s<%s>\n", stnode_type_name(node), stnode_tostr(node));
 	wmem_strbuf_append_printf(buf, "}\n");
 	return wmem_strbuf_finalize(buf);
 }
@@ -307,12 +312,9 @@ static void
 visit_tree(wmem_strbuf_t *buf, stnode_t *node, int level)
 {
 	stnode_t *left, *right;
-	char *str;
 
 	if (stnode_type_id(node) == STTYPE_TEST) {
-		str = stnode_tostr(node);
-		wmem_strbuf_append_printf(buf, "%s(", str);
-		g_free(str);
+		wmem_strbuf_append_printf(buf, "%s(", stnode_tostr(node));
 		sttype_test_get(node, NULL, &left, &right);
 		if (left && right) {
 			wmem_strbuf_append_c(buf, '\n');
@@ -335,9 +337,7 @@ visit_tree(wmem_strbuf_t *buf, stnode_t *node, int level)
 		wmem_strbuf_append(buf, ")");
 	}
 	else {
-		str = stnode_tostr(node);
-		wmem_strbuf_append_printf(buf, "%s<%s>", stnode_type_name(node), str);
-		g_free(str);
+		wmem_strbuf_append_printf(buf, "%s<%s>", stnode_type_name(node), stnode_tostr(node));
 	}
 }
 

epan/dfilter/syntax-tree.h

@@ -59,6 +59,7 @@ typedef struct {
 	uint16_t	flags;
 	gpointer	data;
 	char		*token_value;
+	char 		*repr;
 } stnode_t;
 
 /* These are the sttype_t registration function prototypes. */
@@ -112,7 +113,7 @@ stnode_steal_data(stnode_t *node);
 const char *
 stnode_token_value(stnode_t *node);
 
-char *
+const char *
 stnode_tostr(stnode_t *node);
 
 gboolean