summaryrefslogtreecommitdiffstats
path: root/js/src/jscompartmentinlines.h
blob: c17ba99de24809fca7e2c16976018bef49cb6706 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef jscompartmentinlines_h
#define jscompartmentinlines_h

#include "jscompartment.h"

#include "gc/Barrier.h"

#include "jscntxtinlines.h"

inline void
JSCompartment::initGlobal(js::GlobalObject& global)
{
    MOZ_ASSERT(global.compartment() == this);
    MOZ_ASSERT(!global_);
    global_.set(&global);
}

js::GlobalObject*
JSCompartment::maybeGlobal() const
{
    MOZ_ASSERT_IF(global_, global_->compartment() == this);
    return global_;
}

js::GlobalObject*
JSCompartment::unsafeUnbarrieredMaybeGlobal() const
{
    return *global_.unsafeGet();
}

js::AutoCompartment::AutoCompartment(ExclusiveContext* cx, JSObject* target,
                                     js::AutoLockForExclusiveAccess* maybeLock /* = nullptr */)
  : cx_(cx),
    origin_(cx->compartment_),
    maybeLock_(maybeLock)
{
    cx_->enterCompartment(target->compartment(), maybeLock);
}

js::AutoCompartment::AutoCompartment(ExclusiveContext* cx, JSCompartment* target,
                                     js::AutoLockForExclusiveAccess* maybeLock /* = nullptr */)
  : cx_(cx),
    origin_(cx_->compartment_),
    maybeLock_(maybeLock)
{
    cx_->enterCompartment(target, maybeLock);
}

js::AutoCompartment::~AutoCompartment()
{
    cx_->leaveCompartment(origin_, maybeLock_);
}

inline bool
JSCompartment::wrap(JSContext* cx, JS::MutableHandleValue vp)
{
    /* Only GC things have to be wrapped or copied. */
    if (!vp.isGCThing())
        return true;

    /*
     * Symbols are GC things, but never need to be wrapped or copied because
     * they are always allocated in the atoms compartment.
     */
    if (vp.isSymbol())
        return true;

    /* Handle strings. */
    if (vp.isString()) {
        JS::RootedString str(cx, vp.toString());
        if (!wrap(cx, &str))
            return false;
        vp.setString(str);
        return true;
    }

    MOZ_ASSERT(vp.isObject());

    /*
     * All that's left are objects.
     *
     * Object wrapping isn't the fastest thing in the world, in part because
     * we have to unwrap and invoke the prewrap hook to find the identity
     * object before we even start checking the cache. Neither of these
     * operations are needed in the common case, where we're just wrapping
     * a plain JS object from the wrappee's side of the membrane to the
     * wrapper's side.
     *
     * To optimize this, we note that the cache should only ever contain
     * identity objects - that is to say, objects that serve as the
     * canonical representation for a unique object identity observable by
     * script. Unwrap and prewrap are both steps that we take to get to the
     * identity of an incoming objects, and as such, they shuld never map
     * one identity object to another object. This means that we can safely
     * check the cache immediately, and only risk false negatives. Do this
     * in opt builds, and do both in debug builds so that we can assert
     * that we get the same answer.
     */
#ifdef DEBUG
    JS::RootedObject cacheResult(cx);
#endif
    JS::RootedValue v(cx, vp);
    if (js::WrapperMap::Ptr p = crossCompartmentWrappers.lookup(js::CrossCompartmentKey(v))) {
#ifdef DEBUG
        cacheResult = &p->value().get().toObject();
#else
        vp.set(p->value().get());
        return true;
#endif
    }

    JS::RootedObject obj(cx, &vp.toObject());
    if (!wrap(cx, &obj))
        return false;
    vp.setObject(*obj);
    MOZ_ASSERT_IF(cacheResult, obj == cacheResult);
    return true;
}

#endif /* jscompartmentinlines_h */