Register packet as generational root. refs: #5

.gitignore

@@ -23,3 +23,4 @@ examples/Makefile.encode
 examples/decode
 examples/encode
 ._d/
+.*sw*

src/ogg_flac_stubs.c

@@ -323,8 +323,19 @@ FLAC__StreamEncoderWriteStatus ogg_enc_write_callback(const FLAC__StreamEncoder
       op.b_o_s = 0;
       op.e_o_s = 0;
     }
+
     caml_acquire_runtime_system();
-    caml_callback(h->init_c,value_of_packet(&op));
+
+    value p = value_of_packet(&op);
+
+    caml_register_generational_global_root(&p);
+
+    value ret = caml_callback_exn(h->init_c,p);
+
+    caml_remove_generational_global_root(&p);
+
+    if (Is_exception_result(ret)) caml_raise(Extract_exception(ret));
+
     caml_release_runtime_system();
   }