[wasm] Transferrable modules

We want to restrict structured cloning in Chrome to:
- postMessage senders and receivers that are co-located
in the same process
- indexedDB (just https).

For context, on the Chrome side, we will achieve the postMessage part
by using a mechanism similar to transferrables: the
SerializedScriptValue will have a list of wasm modules, separate from
the serialized data stream; and this list won't be copied cross
process boundaries. The IDB part is achieved by explicitly opting in
reading/writing to the serialization stream. To block attack vectors
in IPC cases, the default for deserialization will be to expect data
in the wasm transfers list.

This change is the V8 side necessary to enabling this design. We
introduce TransferrableModule, an opaque datatype exposed to the
embedder. Internally, TransferrableModules are just serialized data,
because we don't have a better mechanism, at the moment, for
de-contextualizing/re-contextualizing wasm modules (wrt Isolate and

The chrome defaults will be implemented in the
serialization/deserialization delegates on that side. For the v8 side
of things, in the absence of a serialization delegate, the V8
serializer will write to serialization stream. In the absence of a
deserialization delegate, the deserializer won't work. This asymmetry
is intentional - it communicates to the embedder the need to make a
policy decision, otherwise wasm serialization/deserialization won't
work "out of the box".


Review-Url: https://codereview.chromium.org/2748473004
Cr-Commit-Position: refs/heads/master@{#43955}
6 files changed
tree: 0e1939027a2b7e83980fec2fb19c2997d865b3eb
  1. .clang-format
  2. .gitignore
  3. .gn
  4. .ycm_extra_conf.py
  6. BUILD.gn
  8. ChangeLog
  9. DEPS
  11. LICENSE.fdlibm
  12. LICENSE.strongtalk
  13. LICENSE.v8
  14. LICENSE.valgrind
  15. Makefile
  16. Makefile.android
  17. OWNERS
  18. PRESUBMIT.py
  19. README.md
  21. benchmarks/
  22. build_overrides/
  23. codereview.settings
  24. docs/
  25. gni/
  26. gypfiles/
  27. include/
  28. infra/
  29. samples/
  30. snapshot_toolchain.gni
  31. src/
  32. test/
  33. testing/
  34. third_party/
  35. tools/

V8 JavaScript Engine

V8 is Google's open source JavaScript engine.

V8 implements ECMAScript as specified in ECMA-262.

V8 is written in C++ and is used in Google Chrome, the open source browser from Google.

V8 can run standalone, or can be embedded into any C++ application.

V8 Project page: https://github.com/v8/v8/wiki

Getting the Code

Checkout depot tools, and run

    fetch v8

This will checkout V8 into the directory v8 and fetch all of its dependencies. To stay up to date, run

    git pull origin
    gclient sync

For fetching all branches, add the following into your remote configuration in .git/config:

    fetch = +refs/branch-heads/*:refs/remotes/branch-heads/*
    fetch = +refs/tags/*:refs/tags/*


Please follow the instructions mentioned on the V8 wiki.