SFI NaCl: Batch-open resource files

components/nacl/renderer/ppb_nacl_private_impl.cc

Index: components/nacl/renderer/ppb_nacl_private_impl.cc
diff --git a/components/nacl/renderer/ppb_nacl_private_impl.cc b/components/nacl/renderer/ppb_nacl_private_impl.cc
index fb5e6dc9e356f52fef1a591e386cada970e43eaf..498a986d0777da77a935e5dbb04c568abd1089de 100644
--- a/components/nacl/renderer/ppb_nacl_private_impl.cc
+++ b/components/nacl/renderer/ppb_nacl_private_impl.cc
@@ -420,9 +420,16 @@ void LaunchSelLdr(PP_Instance instance,
   IPC::PlatformFileForTransit nexe_for_transit =
       IPC::InvalidPlatformFileForTransit();
 
+#if defined(OS_POSIX)
+  static const bool kPrefetchFiles = true;
+#else
+  // TODO(yusukes): Support OS_WIN.

[Mark Seaborn, 2015/03/20 00:40:52]

What would be required to support Windows?

Since there's no OS_WIN check in the browser process, what would happen if a
compromised renderer skipped this check and requested prefetched files?  Would
it get invalid Windows file handles back?

[Yusuke Sato, 2015/04/16 02:38:45]

Probably nothing, but I haven't confirmed it yet since I don't have Windows dev
environment (yet). Unless there's an urgent need for OS_WIN support, I would
like to enable it later.
 
Good point. Checking this in the renderer side is probably a bad idea. I moved
this #ifdef to browser side so that browser ignores the URL list on OS_WIN for
now.

[Mark Seaborn, 2015/05/04 17:08:39]

What happens if you remove the "#if !defined(OS_WIN)" conditional that's
currently in components/nacl/browser/nacl_host_message_filter.cc?  Does this
pass on the trybots, and if not, what's the failure?  Can you try that, even if
you haven't got a local Windows machine?

I'd rather not have a conditional in here unless the specific reason why this
doesn't work on Windows is commented.

[Yusuke Sato, 2015/05/05 18:27:16]

Thanks to Hidehiko's recent refactoring, it turned out that the code for
releasing prefetched descriptors in NaClProcessHost::~NaClProcessHost() was not
fully compatible with OS_WIN. Updated comments in
components/nacl/browser/nacl_host_message_filter.cc and
components/nacl/browser/nacl_process_host.cc. Let me continue to exclude OS_WIN
for now.

+  static const bool kPrefetchFiles = false;
+#endif
+
   std::vector<std::pair<
     std::string /*key*/, std::string /*url*/> > resource_files_to_prefetch;
-  if (process_type == kNativeNaClProcessType && uses_nonsfi_mode) {
+  if (process_type == kNativeNaClProcessType && kPrefetchFiles) {
     JsonManifest* manifest = GetJsonManifest(instance);
     if (manifest)
       manifest->GetPrefetchableFiles(&resource_files_to_prefetch);