+/* Default handler for extension fields. Expects a pb_field_t structure
+ * in extension->type->arg. */
+static bool checkreturn default_extension_decoder(pb_istream_t *stream,
+ pb_extension_t *extension, uint32_t tag, pb_wire_type_t wire_type)
+{
+ const pb_field_t *field = (const pb_field_t*)extension->type->arg;
+ pb_field_iterator_t iter;
+ bool dummy;
+
+ if (field->tag != tag)
+ return true;
+
+ iter.start = field;
+ iter.pos = field;
+ iter.field_index = 0;
+ iter.required_field_index = 0;
+ iter.dest_struct = extension->dest;
+ iter.pData = extension->dest;
+ iter.pSize = &dummy;
+
+ return decode_field(stream, wire_type, &iter);
+}
+
+/* Try to decode an unknown field as an extension field. Tries each extension
+ * decoder in turn, until one of them handles the field or loop ends. */
+static bool checkreturn decode_extension(pb_istream_t *stream,
+ uint32_t tag, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
+{
+ pb_extension_t *extension = *(pb_extension_t* const *)iter->pData;
+ size_t pos = stream->bytes_left;
+
+ while (extension && pos == stream->bytes_left)
+ {
+ bool status;
+ if (extension->type->decode)
+ status = extension->type->decode(stream, extension, tag, wire_type);
+ else
+ status = default_extension_decoder(stream, extension, tag, wire_type);
+
+ if (!status)
+ return false;
+
+ extension = extension->next;
+ }
+
+ return true;
+}
+
+/* Step through the iterator until an extension field is found or until all
+ * entries have been checked. There can be only one extension field per
+ * message. Returns false if no extension field is found. */
+static bool checkreturn find_extension_field(pb_field_iterator_t *iter)
+{
+ unsigned start = iter->field_index;
+
+ do {
+ if (PB_LTYPE(iter->pos->type) == PB_LTYPE_EXTENSION)
+ return true;
+ pb_field_next(iter);
+ } while (iter->field_index != start);
+
+ return false;
+}
+