Make a NaClDesc ctor for creating descs from NaClFileInfo.

src/trusted/desc/nacl_desc_wrapper.cc

Index: src/trusted/desc/nacl_desc_wrapper.cc
diff --git a/src/trusted/desc/nacl_desc_wrapper.cc b/src/trusted/desc/nacl_desc_wrapper.cc
index ada9cb3aad152810f52670b829e4925ed1652c11..5d7013561809c98302172f25ce3a687abd72645b 100644
--- a/src/trusted/desc/nacl_desc_wrapper.cc
+++ b/src/trusted/desc/nacl_desc_wrapper.cc
@@ -315,6 +315,27 @@ DescWrapper* DescWrapperFactory::MakeFileDesc(int host_os_desc, int mode) {
   return MakeGenericCleanup(desc);
 }
 
+DescWrapper* DescWrapperFactory::MakeFileDescMetadata(struct NaClFileInfo info,
+                                                      int mode) {
+  int error;
+  struct NaClDesc* desc = ImportHostDescCommon(info.desc, mode);
+  if (NULL == desc) {
+    return NULL;
+  }
+  if (info.file_token.lo != 0 || info.file_token.hi != 0) {

[Nick Bray (chromium), 2014/05/02 19:44:35]

See previous CLs for comments on this check.

[jvoung (off chromium), 2014/05/02 20:38:23]

Done.

+    error = (*NACL_VTBL(NaClDesc, desc)->

[Nick Bray (chromium), 2014/05/02 19:44:35]

Why no NaClDescSetFileToken?

[jvoung (off chromium), 2014/05/02 20:38:23]

That's part of desc_cacheabiilty/ and desc_cacheability/ depends on desc/, so I
didn't want to make desc/ depend on desc_cacheability too.

I've moved those helpers over to desc/ and reused them.

+             SetMetadata)(desc,
+                          NACL_DESC_METADATA_FILE_TOKEN_TYPE,
+                          sizeof info.file_token,
+                          (uint8_t const *) &info.file_token);
+    if (0 != error) {
+      NaClDescSafeUnref(desc);
+      return NULL;
+    }
+  }
+  return MakeGenericCleanup(desc);
+}
+
 DescWrapper* DescWrapperFactory::MakeFileDescQuota(int host_os_desc,
                                                    int mode,
                                                    const uint8_t* file_id) {