libctf: add ctf_member_count

This returns the number of members in a struct or union, or the number
of enumerations in an enum.  (This was only available before now by
iterating across every member, but it can be returned much faster than
that.)

include/
	* ctf-api.h (ctf_member_count): New.

libctf/
	* ctf-types.c (ctf_member_count): New.
	* libctf.ver: New public function.

1 files changed, 24 insertions, 0 deletions

diff --git a/libctf/ctf-types.c b/libctf/ctf-types.c
index d8f848c..93967c6 100644
--- a/libctf/ctf-types.c
+++ b/libctf/ctf-types.c
@@ -963,6 +963,30 @@ ctf_type_compat (ctf_file_t *lfp, ctf_id_t ltype,
     }
 }
 
+/* Return the number of members in a STRUCT or UNION, or the number of
+   enumerators in an ENUM.  */
+
+int
+ctf_member_count (ctf_file_t *fp, ctf_id_t type)
+{
+  ctf_file_t *ofp = fp;
+  const ctf_type_t *tp;
+  uint32_t kind;
+
+  if ((type = ctf_type_resolve (fp, type)) == CTF_ERR)
+    return -1;			/* errno is set for us.  */
+
+  if ((tp = ctf_lookup_by_id (&fp, type)) == NULL)
+    return -1;			/* errno is set for us.  */
+
+  kind = LCTF_INFO_KIND (fp, tp->ctt_info);
+
+  if (kind != CTF_K_STRUCT && kind != CTF_K_UNION && kind != CTF_K_ENUM)
+    return (ctf_set_errno (ofp, ECTF_NOTSUE));
+
+  return LCTF_INFO_VLEN (fp, tp->ctt_info);
+}
+
 /* Return the type and offset for a given member of a STRUCT or UNION.  */
 
 int