Make a NaClDesc ctor for creating descs from NaClFileInfo.

src/trusted/desc_cacheability/desc_cacheability.c

Index: src/trusted/desc_cacheability/desc_cacheability.c
diff --git a/src/trusted/desc_cacheability/desc_cacheability.c b/src/trusted/desc_cacheability/desc_cacheability.c
index ab3badae7d07cf46c4f0a6fe801b8beec72ed390..21d4857faa9485687807d38a3dd03876320f0bd9 100644
--- a/src/trusted/desc_cacheability/desc_cacheability.c
+++ b/src/trusted/desc_cacheability/desc_cacheability.c
@@ -8,55 +8,15 @@
 
 #include "native_client/src/include/portability.h"
 #include "native_client/src/public/desc_metadata_types.h"
+#include "native_client/src/public/nacl_file_info.h"
 #include "native_client/src/shared/platform/nacl_log.h"
 #include "native_client/src/trusted/desc/nacl_desc_base.h"
+#include "native_client/src/trusted/desc/nacl_desc_file_info.h"
 #include "native_client/src/trusted/desc/nacl_desc_io.h"
 #include "native_client/src/trusted/service_runtime/include/sys/fcntl.h"
-#include "native_client/src/trusted/validator/nacl_file_info.h"
 #include "native_client/src/trusted/validator/rich_file_info.h"
 #include "native_client/src/trusted/validator/validation_cache.h"
 
-int NaClDescSetFileToken(struct NaClDesc *desc,
-                         struct NaClFileToken const *token) {
-  int error;
-  error = (*NACL_VTBL(NaClDesc, desc)->
-           SetMetadata)(desc,
-                        NACL_DESC_METADATA_FILE_TOKEN_TYPE,
-                        sizeof *token, (uint8_t const *) token);
-  if (0 != error) {
-    NaClLog(4, "NaClDescSetFileToken: failed, errno %d\n", -error);
-    return 0;
-  }
-  return 1;
-}
-
-int NaClDescGetFileToken(struct NaClDesc *desc,
-                         struct NaClFileToken *out_token) {
-  int32_t metadata_type;
-  uint32_t metadata_bytes;
-
-  metadata_bytes = (uint32_t) sizeof *out_token;
-  metadata_type = (*NACL_VTBL(NaClDesc, desc)->
-                   GetMetadata)(desc, &metadata_bytes,
-                                (uint8_t *) out_token);
-  if (NACL_DESC_METADATA_NONE_TYPE == metadata_type) {
-    NaClLog(4, "NaClDescGetFileToken: no meta data, cannot map\n");
-    return 0;
-  } else if (NACL_DESC_METADATA_FILE_TOKEN_TYPE != metadata_type) {
-    return 0;
-  } else if (metadata_bytes != (uint32_t) sizeof *out_token) {
-    /* there is supposed to be a file token, but wrong size? */
-    NaClLog(LOG_WARNING,
-            "NaClDescGetFileToken: purported file token present,"
-            " but token size is incorrect.\n");
-    return 0;
-  }
-  NaClLog(4,
-          "NaClDescGetFileToken: got token 0x%"NACL_PRIx64":%"NACL_PRIx64"\n",
-          out_token->hi, out_token->lo);
-  return 1;
-}
-
 struct NaClDesc *NaClExchangeFileTokenForMappableDesc(
     struct NaClFileToken *file_token,
     struct NaClValidationCache *validation_cache) {
@@ -71,7 +31,7 @@ struct NaClDesc *NaClExchangeFileTokenForMappableDesc(
    * resolve.  In this case, assume nothing about the providence of
    * the file.
    */
-  if (!(file_token->lo == 0 && file_token->hi == 0) &&
+  if (NaClFileTokenIsValid(file_token) &&
       validation_cache->ResolveFileToken != NULL &&
       validation_cache->ResolveFileToken(validation_cache->handle,
                                          file_token,