Resurrect Petr's 64-bit dynamic code modification CL:...

src/trusted/validator_x86/nccopycode.h

 /*
  * Copyright 2010 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can
  * be found in the LICENSE file.
  */
 
 #ifndef NATIVE_CLIENT_SRC_TRUSTED_VALIDATOR_X86_NCCOPYCODE_H_
 #define NATIVE_CLIENT_SRC_TRUSTED_VALIDATOR_X86_NCCOPYCODE_H_
 
 #include "native_client/src/trusted/validator_x86/types_memory_model.h"
 
-/* copies code from src to dest in a thread safe way, returns 0 on success */
+#if NACL_TARGET_SUBARCH == 32
+/* Copies code from src to dest in a thread safe way, returns 1 on success,
+ * returns 0 on error. This will likely assert on error to avoid partially
+ * copied code or undefined state.
+ */
 int NCCopyCode(uint8_t *dst, uint8_t *src, NaClPcAddress vbase,
                 size_t sz, int bundle_size);
 
+#elif NACL_TARGET_SUBARCH == 64
+/* Copies code from src to dest in a thread safe way, returns 1 on success,
+ * returns 0 on error. This will likely assert on error to avoid partially
+ * copied code or undefined state.
+ */
+int NaClCopyCodeIter(uint8_t *dst, uint8_t *src,
+                     NaClPcAddress vbase, size_t size);
+#else
+#error "Unknown Platform"
+#endif
+
 #endif  /* NATIVE_CLIENT_SRC_TRUSTED_VALIDATOR_X86_COPYCODE_H_ */