js/src/jscompartmentinlines.h@b8a032363ba2 (annotated)
js/src/jscompartmentinlines.h
Thu, 22 Jan 2015 13:21:57 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Thu, 22 Jan 2015 13:21:57 +0100
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
- permissions
- -rw-r--r--
Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6
| michael@0 | 1 | /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- |
| michael@0 | 2 | * vim: set ts=8 sts=4 et sw=4 tw=99: |
| michael@0 | 3 | * This Source Code Form is subject to the terms of the Mozilla Public |
| michael@0 | 4 | * License, v. 2.0. If a copy of the MPL was not distributed with this |
| michael@0 | 5 | * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ |
| michael@0 | 6 | |
| michael@0 | 7 | #ifndef jscompartmentinlines_h |
| michael@0 | 8 | #define jscompartmentinlines_h |
| michael@0 | 9 | |
| michael@0 | 10 | #include "jscompartment.h" |
| michael@0 | 11 | |
| michael@0 | 12 | #include "gc/Barrier-inl.h" |
| michael@0 | 13 | |
| michael@0 | 14 | inline void |
| michael@0 | 15 | JSCompartment::initGlobal(js::GlobalObject &global) |
| michael@0 | 16 | { |
| michael@0 | 17 | JS_ASSERT(global.compartment() == this); |
| michael@0 | 18 | JS_ASSERT(!global_); |
| michael@0 | 19 | global_ = &global; |
| michael@0 | 20 | } |
| michael@0 | 21 | |
| michael@0 | 22 | js::GlobalObject * |
| michael@0 | 23 | JSCompartment::maybeGlobal() const |
| michael@0 | 24 | { |
| michael@0 | 25 | JS_ASSERT_IF(global_, global_->compartment() == this); |
| michael@0 | 26 | return global_; |
| michael@0 | 27 | } |
| michael@0 | 28 | |
| michael@0 | 29 | js::AutoCompartment::AutoCompartment(ExclusiveContext *cx, JSObject *target) |
| michael@0 | 30 | : cx_(cx), |
| michael@0 | 31 | origin_(cx->compartment_) |
| michael@0 | 32 | { |
| michael@0 | 33 | cx_->enterCompartment(target->compartment()); |
| michael@0 | 34 | } |
| michael@0 | 35 | |
| michael@0 | 36 | js::AutoCompartment::AutoCompartment(ExclusiveContext *cx, JSCompartment *target) |
| michael@0 | 37 | : cx_(cx), |
| michael@0 | 38 | origin_(cx_->compartment_) |
| michael@0 | 39 | { |
| michael@0 | 40 | cx_->enterCompartment(target); |
| michael@0 | 41 | } |
| michael@0 | 42 | |
| michael@0 | 43 | js::AutoCompartment::~AutoCompartment() |
| michael@0 | 44 | { |
| michael@0 | 45 | cx_->leaveCompartment(origin_); |
| michael@0 | 46 | } |
| michael@0 | 47 | |
| michael@0 | 48 | inline bool |
| michael@0 | 49 | JSCompartment::wrap(JSContext *cx, JS::MutableHandleValue vp, JS::HandleObject existing) |
| michael@0 | 50 | { |
| michael@0 | 51 | JS_ASSERT_IF(existing, vp.isObject()); |
| michael@0 | 52 | |
| michael@0 | 53 | /* Only GC things have to be wrapped or copied. */ |
| michael@0 | 54 | if (!vp.isMarkable()) |
| michael@0 | 55 | return true; |
| michael@0 | 56 | |
| michael@0 | 57 | /* Handle strings. */ |
| michael@0 | 58 | if (vp.isString()) { |
| michael@0 | 59 | JS::RootedString str(cx, vp.toString()); |
| michael@0 | 60 | if (!wrap(cx, str.address())) |
| michael@0 | 61 | return false; |
| michael@0 | 62 | vp.setString(str); |
| michael@0 | 63 | return true; |
| michael@0 | 64 | } |
| michael@0 | 65 | |
| michael@0 | 66 | JS_ASSERT(vp.isObject()); |
| michael@0 | 67 | |
| michael@0 | 68 | /* |
| michael@0 | 69 | * All that's left are objects. |
| michael@0 | 70 | * |
| michael@0 | 71 | * Object wrapping isn't the fastest thing in the world, in part because |
| michael@0 | 72 | * we have to unwrap and invoke the prewrap hook to find the identity |
| michael@0 | 73 | * object before we even start checking the cache. Neither of these |
| michael@0 | 74 | * operations are needed in the common case, where we're just wrapping |
| michael@0 | 75 | * a plain JS object from the wrappee's side of the membrane to the |
| michael@0 | 76 | * wrapper's side. |
| michael@0 | 77 | * |
| michael@0 | 78 | * To optimize this, we note that the cache should only ever contain |
| michael@0 | 79 | * identity objects - that is to say, objects that serve as the |
| michael@0 | 80 | * canonical representation for a unique object identity observable by |
| michael@0 | 81 | * script. Unwrap and prewrap are both steps that we take to get to the |
| michael@0 | 82 | * identity of an incoming objects, and as such, they shuld never map |
| michael@0 | 83 | * one identity object to another object. This means that we can safely |
| michael@0 | 84 | * check the cache immediately, and only risk false negatives. Do this |
| michael@0 | 85 | * in opt builds, and do both in debug builds so that we can assert |
| michael@0 | 86 | * that we get the same answer. |
| michael@0 | 87 | */ |
| michael@0 | 88 | #ifdef DEBUG |
| michael@0 | 89 | JS::RootedObject cacheResult(cx); |
| michael@0 | 90 | #endif |
| michael@0 | 91 | JS::RootedValue v(cx, vp); |
| michael@0 | 92 | if (js::WrapperMap::Ptr p = crossCompartmentWrappers.lookup(v)) { |
| michael@0 | 93 | #ifdef DEBUG |
| michael@0 | 94 | cacheResult = &p->value().get().toObject(); |
| michael@0 | 95 | #else |
| michael@0 | 96 | vp.set(p->value()); |
| michael@0 | 97 | return true; |
| michael@0 | 98 | #endif |
| michael@0 | 99 | } |
| michael@0 | 100 | |
| michael@0 | 101 | JS::RootedObject obj(cx, &vp.toObject()); |
| michael@0 | 102 | if (!wrap(cx, &obj, existing)) |
| michael@0 | 103 | return false; |
| michael@0 | 104 | vp.setObject(*obj); |
| michael@0 | 105 | JS_ASSERT_IF(cacheResult, obj == cacheResult); |
| michael@0 | 106 | return true; |
| michael@0 | 107 | } |
| michael@0 | 108 | |
| michael@0 | 109 | #endif /* jscompartmentinlines_h */ |
