NaCl: enable meta-based validation for shared libraries.

ppapi/native_client/src/trusted/plugin/file_downloader.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "native_client/src/trusted/plugin/file_downloader.h"
 
 #include <stdio.h>
+#include <string.h>
 #include <string>
 
 #include "native_client/src/include/portability_io.h"
 #include "native_client/src/shared/platform/nacl_check.h"
 #include "native_client/src/shared/platform/nacl_time.h"
 #include "native_client/src/trusted/plugin/callback_source.h"
 #include "native_client/src/trusted/plugin/plugin.h"
 #include "native_client/src/trusted/plugin/utility.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/c/ppb_file_io.h"
@@ skipping 120 matching lines @@
   // invocation of the user callback. The user code will not be reentered.
   pp::CompletionCallback onload_callback =
       callback_factory_.NewCallback(start_notify);
   int32_t pp_error = url_loader_.Open(url_request, onload_callback);
   PLUGIN_PRINTF(("FileDownloader::Open (pp_error=%"NACL_PRId32")\n", pp_error));
   CHECK(pp_error == PP_OK_COMPLETIONPENDING);
   return true;
 }
 
 void FileDownloader::OpenFast(const nacl::string& url,
-                              PP_FileHandle file_handle) {
+                              PP_FileHandle file_handle,
+                              uint64_t nonce) {
   PLUGIN_PRINTF(("FileDownloader::OpenFast (url=%s)\n", url.c_str()));
   CHECK(instance_ != NULL);
   open_time_ = NaClGetTimeOfDayMicroseconds();
   status_code_ = NACL_HTTP_STATUS_OK;
   url_to_open_ = url;
   url_ = url;
   mode_ = DOWNLOAD_NONE;
   file_handle_ = file_handle;
+  nonce_ = nonce;
 }
 
-int32_t FileDownloader::GetPOSIXFileDescriptor() {
+struct NaClFileInfo FileDownloader::GetFileInfo() {
+  struct NaClFileInfo info;
+  memset(&info, 0, sizeof(info));
+  info.desc = -1;
   int32_t file_desc = NACL_NO_FILE_DESC;
   if (not_streaming() && file_handle_ != PP_kInvalidFileHandle) {
 #if NACL_WINDOWS
     // On Windows, valid handles are 32 bit unsigned integers so this is safe.
     file_desc = reinterpret_cast<uintptr_t>(file_handle_);
 #else
     file_desc = file_handle_;
 #endif
+    info.nonce = nonce_;
   } else {
     if (!streaming_to_file()) {
-      return NACL_NO_FILE_DESC;
+      return info;

[dmichael (off chromium), 2013/05/15 18:37:53]

I find these error returns less obvious now. Not sure of a nicer way to do it.
You could maybe do:
return { NACL_NO_FILE_DESC, nonce };
? That has the downside that NaClFileInfo can only change by appending, though.

[Nick Bray (chromium), 2013/05/16 16:38:17]

The file info structure is defined in the NaCl repo, so I want to avoid any
assumptions about the layout.  I get what you're saying and considered it
myself, but didn't see a better way.

[dmichael (off chromium), 2013/05/16 17:08:35]

How about a simple little helper function in the unnamed namespace, and do:
MakeNaClFileInfo(NACL_NO_FILE_DESC, nonce);
here.
MakeNaClFileInfo would do the memset and assign those fields without making
assumptions about layout.

Or if you have any better ideas, I'm open. I would just like it to be super
obvious that these branches are error conditions somehow.

[Nick Bray (chromium), 2013/05/16 17:44:15]

Didn't think of that one.  Good idea.  Done.

     }
     // Use the trusted interface to get the file descriptor.
     if (file_io_trusted_interface_ == NULL) {
-      return NACL_NO_FILE_DESC;
+      return info;
     }
     file_desc = file_io_trusted_interface_->GetOSFileDescriptor(
         file_reader_.pp_resource());
   }
 
 #if NACL_WINDOWS
   // Convert the Windows HANDLE from Pepper to a POSIX file descriptor.
   int32_t posix_desc = _open_osfhandle(file_desc, _O_RDWR | _O_BINARY);
   if (posix_desc == -1) {
     // Close the Windows HANDLE if it can't be converted.
     CloseHandle(reinterpret_cast<HANDLE>(file_desc));
-    return NACL_NO_FILE_DESC;
+    return info;
   }
   file_desc = posix_desc;
 #endif
 
-  return file_desc;
+  info.desc = file_desc;
+  return info;
 }
 
 int64_t FileDownloader::TimeSinceOpenMilliseconds() const {
   int64_t now = NaClGetTimeOfDayMicroseconds();
   // If Open() wasn't called or we somehow return an earlier time now, just
   // return the 0 rather than worse nonsense values.
   if (open_time_ < 0 || now < open_time_)
     return 0;
   return (now - open_time_) / NACL_MICROS_PER_MILLI;
 }
@@ skipping 196 matching lines @@
 
 bool FileDownloader::streaming_to_user() const {
   return mode_ == DOWNLOAD_STREAM;
 }
 
 bool FileDownloader::not_streaming() const {
   return mode_ == DOWNLOAD_NONE;
 }
 
 }  // namespace plugin