Reserve unknown fields in php (#3659)

* Reserve unknown fields in upb
1) For decoding, an unknownfields will be lazily created on message,
which contains bytes of unknown fields.
2) For encoding, if the unknownfields is present on message, all bytes
contained in it will be serialized.

* Register the function to encode unknown field at decode time.

* Remove upb_handlers_setaddunknown

* Use upb_sink_putunknown in decoder

* Remove upb_pb_encoder_encode_unknown

* Do not expose encode_unknown

* Implement reserve unknown field in php Implement.

* Make buffer private to CodedInputStream

1 files changed, 8 insertions, 1 deletions

diff --git a/php/ext/google/protobuf/storage.c b/php/ext/google/protobuf/storage.c
index a0488ecb..e7910c85 100644
--- a/php/ext/google/protobuf/storage.c
+++ b/php/ext/google/protobuf/storage.c
@@ -583,9 +583,12 @@ MessageLayout* create_layout(const upb_msgdef* msgdef) {
   upb_msg_oneof_iter oit;
   size_t off = 0;
   int i = 0;
+
+  // Reserve space for unknown fields.
+  off += sizeof(void*);
+
   TSRMLS_FETCH();
   Descriptor* desc = UNBOX_HASHTABLE_VALUE(Descriptor, get_def_obj(msgdef));
-
   layout->fields = ALLOC_N(MessageField, nfields);
 
   for (upb_msg_field_begin(&it, msgdef); !upb_msg_field_done(&it);
@@ -744,6 +747,10 @@ void layout_init(MessageLayout* layout, void* storage,
                  zend_object* object PHP_PROTO_TSRMLS_DC) {
   int i;
   upb_msg_field_iter it;
+
+  // Init unknown fields
+  memset(storage, 0, sizeof(void*));
+
   for (upb_msg_field_begin(&it, layout->msgdef), i = 0; !upb_msg_field_done(&it);
        upb_msg_field_next(&it), i++) {
     const upb_fielddef* field = upb_msg_iter_field(&it);