[PATCH nft 2/5] datatype: don't clone static name/desc strings for datatype

[Thomas Haller <thaller@redhat.com>]

Avoid cloning static strings for "struct datatype". With
concat_type_alloc(), the name/desc are generated dynamically and need to
be allocated. However, datatype_clone() only reuses the original
name/desc strings. If those strings are static already, we don't need to
clone them.

Note that there are no other places that also want to change or set the
name/desc. If there were, they would need to handle the new fact that
the strings may or may not be dynamically allocated.

Signed-off-by: Thomas Haller <thaller@redhat.com>
---
 include/datatype.h |  2 ++
 src/datatype.c     | 15 ++++++++++-----
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/include/datatype.h b/include/datatype.h
index b53a739e1e6c..465ade290652 100644
--- a/include/datatype.h
+++ b/include/datatype.h
@@ -132,6 +132,7 @@ struct parse_ctx;
  * @f_prefix:	preferred representation for ranges is a prefix
  * @f_alloc:	whether the instance is dynamically allocated. If not, datatype_get() and
  *		datatype_free() are NOPs.
+ * @f_allocated_strings: whether @name and @desc are heap allocated or static.
  * @name:	type name
  * @desc:	type description
  * @basetype:	basetype for subtypes, determines type compatibility
@@ -153,6 +154,7 @@ struct datatype {
 	enum byteorder			byteorder;
 	bool				f_prefix:1;
 	bool				f_alloc:1;
+	bool				f_allocated_strings:1;
 
 	const char			*name;
 	const char			*desc;
diff --git a/src/datatype.c b/src/datatype.c
index 464eb49171c6..1c557a06c751 100644
--- a/src/datatype.c
+++ b/src/datatype.c
@@ -1244,8 +1244,10 @@ struct datatype *datatype_clone(const struct datatype *orig_dtype)
 
 	dtype = xzalloc(sizeof(*dtype));
 	*dtype = *orig_dtype;
-	dtype->name = xstrdup(orig_dtype->name);
-	dtype->desc = xstrdup(orig_dtype->desc);
+	if (orig_dtype->f_allocated_strings) {
+		dtype->name = xstrdup(orig_dtype->name);
+		dtype->desc = xstrdup(orig_dtype->desc);
+	}
 	dtype->f_alloc = true;
 	dtype->refcnt = 1;
 
@@ -1265,8 +1267,10 @@ void datatype_free(const struct datatype *ptr)
 	if (--dtype->refcnt > 0)
 		return;
 
-	xfree(dtype->name);
-	xfree(dtype->desc);
+	if (dtype->f_allocated_strings) {
+		xfree(dtype->name);
+		xfree(dtype->desc);
+	}
 	xfree(dtype);
 }
 
@@ -1299,7 +1303,8 @@ const struct datatype *concat_type_alloc(uint32_t type)
 	dtype		= datatype_alloc();
 	dtype->type	= type;
 	dtype->size	= size;
-	dtype->subtypes = subtypes;
+	dtype->subtypes	= subtypes;
+	dtype->f_allocated_strings = true;
 	dtype->name	= xstrdup(name);
 	dtype->desc	= xstrdup(desc);
 	dtype->parse	= concat_type_parse;
-- 
2.41.0