Fix callback pointer corruption in proto3 mode (issue #249)

diff --git a/pb_decode.c b/pb_decode.c
index a8cd61a..e2e90ca 100644 (file)
--- a/pb_decode.c
+++ b/pb_decode.c
@@ -780,7 +780,7 @@ static void pb_field_set_to_default(pb_field_iter_t *iter)
     else if (PB_ATYPE(type) == PB_ATYPE_STATIC)
     {
         bool init_data = true;
-        if (PB_HTYPE(type) == PB_HTYPE_OPTIONAL)
+        if (PB_HTYPE(type) == PB_HTYPE_OPTIONAL && iter->pSize != iter->pData)
         {
             /* Set has_field to false. Still initialize the optional field
              * itself also. */