jscntxtinlines.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 * 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 jscntxtinlines_h
#define jscntxtinlines_h

#include "jscntxt.h"
#include "jscompartment.h"

#include "jsiter.h"

#include "builtin/Object.h"
#include "jit/JitFrames.h"
#include "vm/HelperThreads.h"
#include "vm/Interpreter.h"
#include "vm/ProxyObject.h"
#include "vm/Symbol.h"

namespace js {

#ifdef JS_CRASH_DIAGNOSTICS
class CompartmentChecker
{
    JSCompartment *compartment;

  public:
    explicit CompartmentChecker(ExclusiveContext *cx)
      : compartment(cx->compartment())
    {
#ifdef DEBUG
        // In debug builds, make sure the embedder passed the cx it claimed it
        // was going to use.
        JSContext *activeContext = nullptr;
        if (cx->isJSContext())
            activeContext = cx->asJSContext()->runtime()->activeContext;
        MOZ_ASSERT_IF(activeContext, cx == activeContext);
#endif
    }

    /*
     * Set a breakpoint here (break js::CompartmentChecker::fail) to debug
     * compartment mismatches.
     */
    static void fail(JSCompartment *c1, JSCompartment *c2) {
        printf("*** Compartment mismatch %p vs. %p\n", (void *) c1, (void *) c2);
        MOZ_CRASH();
    }

    static void fail(JS::Zone *z1, JS::Zone *z2) {
        printf("*** Zone mismatch %p vs. %p\n", (void *) z1, (void *) z2);
        MOZ_CRASH();
    }

    /* Note: should only be used when neither c1 nor c2 may be the atoms compartment. */
    static void check(JSCompartment *c1, JSCompartment *c2) {
        MOZ_ASSERT(!c1->runtimeFromAnyThread()->isAtomsCompartment(c1));
        MOZ_ASSERT(!c2->runtimeFromAnyThread()->isAtomsCompartment(c2));
        if (c1 != c2)
            fail(c1, c2);
    }

    void check(JSCompartment *c) {
        if (c && !compartment->runtimeFromAnyThread()->isAtomsCompartment(c)) {
            if (!compartment)
                compartment = c;
            else if (c != compartment)
                fail(compartment, c);
        }
    }

    void checkZone(JS::Zone *z) {
        if (compartment && z != compartment->zone())
            fail(compartment->zone(), z);
    }

    void check(JSObject *obj) {
        if (obj)
            check(obj->compartment());
    }

    template<typename T>
    void check(const Rooted<T>& rooted) {
        check(rooted.get());
    }

    template<typename T>
    void check(Handle<T> handle) {
        check(handle.get());
    }

    void check(JSString *str) {
        if (!str->isAtom())
            checkZone(str->zone());
    }

    void check(const js::Value &v) {
        if (v.isObject())
            check(&v.toObject());
        else if (v.isString())
            check(v.toString());
    }

    void check(const ValueArray &arr) {
        for (size_t i = 0; i < arr.length; i++)
            check(arr.array[i]);
    }

    void check(const JSValueArray &arr) {
        for (size_t i = 0; i < arr.length; i++)
            check(arr.array[i]);
    }

    void check(const JS::HandleValueArray &arr) {
        for (size_t i = 0; i < arr.length(); i++)
            check(arr[i]);
    }

    void check(const CallArgs &args) {
        for (Value *p = args.base(); p != args.end(); ++p)
            check(*p);
    }

    void check(jsid id) {}

    void check(JSScript *script) {
        if (script)
            check(script->compartment());
    }

    void check(InterpreterFrame *fp);
    void check(AbstractFramePtr frame);
    void check(SavedStacks *stacks);
};
#endif /* JS_CRASH_DIAGNOSTICS */

/*
 * Don't perform these checks when called from a finalizer. The checking
 * depends on other objects not having been swept yet.
 */
#define START_ASSERT_SAME_COMPARTMENT()                                       \
    if (cx->isJSContext() && cx->asJSContext()->runtime()->isHeapBusy())      \
        return;                                                               \
    CompartmentChecker c(cx)

template <class T1> inline void
assertSameCompartment(ExclusiveContext *cx, const T1 &t1)
{
#ifdef JS_CRASH_DIAGNOSTICS
    START_ASSERT_SAME_COMPARTMENT();
    c.check(t1);
#endif
}

template <class T1> inline void
assertSameCompartmentDebugOnly(ExclusiveContext *cx, const T1 &t1)
{
#if defined(DEBUG) && defined(JS_CRASH_DIAGNOSTICS)
    START_ASSERT_SAME_COMPARTMENT();
    c.check(t1);
#endif
}

template <class T1, class T2> inline void
assertSameCompartment(ExclusiveContext *cx, const T1 &t1, const T2 &t2)
{
#ifdef JS_CRASH_DIAGNOSTICS
    START_ASSERT_SAME_COMPARTMENT();
    c.check(t1);
    c.check(t2);
#endif
}

template <class T1, class T2, class T3> inline void
assertSameCompartment(ExclusiveContext *cx, const T1 &t1, const T2 &t2, const T3 &t3)
{
#ifdef JS_CRASH_DIAGNOSTICS
    START_ASSERT_SAME_COMPARTMENT();
    c.check(t1);
    c.check(t2);
    c.check(t3);
#endif
}

template <class T1, class T2, class T3, class T4> inline void
assertSameCompartment(ExclusiveContext *cx,
                      const T1 &t1, const T2 &t2, const T3 &t3, const T4 &t4)
{
#ifdef JS_CRASH_DIAGNOSTICS
    START_ASSERT_SAME_COMPARTMENT();
    c.check(t1);
    c.check(t2);
    c.check(t3);
    c.check(t4);
#endif
}

template <class T1, class T2, class T3, class T4, class T5> inline void
assertSameCompartment(ExclusiveContext *cx,
                      const T1 &t1, const T2 &t2, const T3 &t3, const T4 &t4, const T5 &t5)
{
#ifdef JS_CRASH_DIAGNOSTICS
    START_ASSERT_SAME_COMPARTMENT();
    c.check(t1);
    c.check(t2);
    c.check(t3);
    c.check(t4);
    c.check(t5);
#endif
}

#undef START_ASSERT_SAME_COMPARTMENT

STATIC_PRECONDITION_ASSUME(ubound(args.argv_) >= argc)
MOZ_ALWAYS_INLINE bool
CallJSNative(JSContext *cx, Native native, const CallArgs &args)
{
    JS_CHECK_RECURSION(cx, return false);

#ifdef DEBUG
    bool alreadyThrowing = cx->isExceptionPending();
#endif
    assertSameCompartment(cx, args);
    bool ok = native(cx, args.length(), args.base());
    if (ok) {
        assertSameCompartment(cx, args.rval());
        MOZ_ASSERT_IF(!alreadyThrowing, !cx->isExceptionPending());
    }
    return ok;
}

STATIC_PRECONDITION_ASSUME(ubound(args.argv_) >= argc)
MOZ_ALWAYS_INLINE bool
CallNativeImpl(JSContext *cx, NativeImpl impl, const CallArgs &args)
{
#ifdef DEBUG
    bool alreadyThrowing = cx->isExceptionPending();
#endif
    assertSameCompartment(cx, args);
    bool ok = impl(cx, args);
    if (ok) {
        assertSameCompartment(cx, args.rval());
        MOZ_ASSERT_IF(!alreadyThrowing, !cx->isExceptionPending());
    }
    return ok;
}

STATIC_PRECONDITION(ubound(args.argv_) >= argc)
MOZ_ALWAYS_INLINE bool
CallJSNativeConstructor(JSContext *cx, Native native, const CallArgs &args)
{
#ifdef DEBUG
    RootedObject callee(cx, &args.callee());
#endif

    MOZ_ASSERT(args.thisv().isMagic());
    if (!CallJSNative(cx, native, args))
        return false;

    /*
     * Native constructors must return non-primitive values on success.
     * Although it is legal, if a constructor returns the callee, there is a
     * 99.9999% chance it is a bug. If any valid code actually wants the
     * constructor to return the callee, the assertion can be removed or
     * (another) conjunct can be added to the antecedent.
     *
     * Exceptions:
     *
     * - Proxies are exceptions to both rules: they can return primitives and
     *   they allow content to return the callee.
     *
     * - CallOrConstructBoundFunction is an exception as well because we might
     *   have used bind on a proxy function.
     *
     * - new Iterator(x) is user-hookable; it returns x.__iterator__() which
     *   could be any object.
     *
     * - (new Object(Object)) returns the callee.
     */
    MOZ_ASSERT_IF(native != js::proxy_Construct &&
                  native != js::CallOrConstructBoundFunction &&
                  native != js::IteratorConstructor &&
                  (!callee->is<JSFunction>() || callee->as<JSFunction>().native() != obj_construct),
                  args.rval().isObject() && callee != &args.rval().toObject());

    return true;
}

MOZ_ALWAYS_INLINE bool
CallJSPropertyOp(JSContext *cx, PropertyOp op, HandleObject receiver, HandleId id, MutableHandleValue vp)
{
    JS_CHECK_RECURSION(cx, return false);

    assertSameCompartment(cx, receiver, id, vp);
    bool ok = op(cx, receiver, id, vp);
    if (ok)
        assertSameCompartment(cx, vp);
    return ok;
}

MOZ_ALWAYS_INLINE bool
CallJSPropertyOpSetter(JSContext *cx, StrictPropertyOp op, HandleObject obj, HandleId id,
                       bool strict, MutableHandleValue vp)
{
    JS_CHECK_RECURSION(cx, return false);

    assertSameCompartment(cx, obj, id, vp);
    return op(cx, obj, id, strict, vp);
}

static inline bool
CallJSDeletePropertyOp(JSContext *cx, JSDeletePropertyOp op, HandleObject receiver, HandleId id,
                       bool *succeeded)
{
    JS_CHECK_RECURSION(cx, return false);

    assertSameCompartment(cx, receiver, id);
    if (op)
        return op(cx, receiver, id, succeeded);
    *succeeded = true;
    return true;
}

inline bool
CallSetter(JSContext *cx, HandleObject obj, HandleId id, StrictPropertyOp op, unsigned attrs,
           bool strict, MutableHandleValue vp)
{
    if (attrs & JSPROP_SETTER) {
        RootedValue opv(cx, CastAsObjectJsval(op));
        return InvokeGetterOrSetter(cx, obj, opv, 1, vp.address(), vp);
    }

    if (attrs & JSPROP_GETTER)
        return js_ReportGetterOnlyAssignment(cx, strict);

    if (!op)
        return true;

    return CallJSPropertyOpSetter(cx, op, obj, id, strict, vp);
}

inline uintptr_t
GetNativeStackLimit(ExclusiveContext *cx)
{
    StackKind kind;
    if (cx->isJSContext()) {
        kind = cx->asJSContext()->runningWithTrustedPrincipals()
                 ? StackForTrustedScript : StackForUntrustedScript;
    } else {
        // For other threads, we just use the trusted stack depth, since it's
        // unlikely that we'll be mixing trusted and untrusted code together.
        kind = StackForTrustedScript;
    }
    return cx->perThreadData->nativeStackLimit[kind];
}

inline LifoAlloc &
ExclusiveContext::typeLifoAlloc()
{
    return zone()->types.typeLifoAlloc;
}

}  /* namespace js */

inline void
JSContext::setPendingException(js::Value v)
{
    MOZ_ASSERT(!IsPoisonedValue(v));
    // overRecursed_ is set after the fact by js_ReportOverRecursed.
    this->overRecursed_ = false;
    this->throwing = true;
    this->unwrappedException_ = v;
    // We don't use assertSameCompartment here to allow
    // js::SetPendingExceptionCrossContext to work.
    MOZ_ASSERT_IF(v.isObject(), v.toObject().compartment() == compartment());
}

inline bool
JSContext::runningWithTrustedPrincipals() const
{
    return !compartment() || compartment()->principals == runtime()->trustedPrincipals();
}

inline void
js::ExclusiveContext::enterCompartment(JSCompartment *c)
{
    enterCompartmentDepth_++;
    c->enter();
    setCompartment(c);
}

inline void
js::ExclusiveContext::enterNullCompartment()
{
    enterCompartmentDepth_++;
    setCompartment(nullptr);
}

inline void
js::ExclusiveContext::leaveCompartment(JSCompartment *oldCompartment)
{
    MOZ_ASSERT(hasEnteredCompartment());
    enterCompartmentDepth_--;

    // Only call leave() after we've setCompartment()-ed away from the current
    // compartment.
    JSCompartment *startingCompartment = compartment_;
    setCompartment(oldCompartment);
    if (startingCompartment)
        startingCompartment->leave();
}

inline void
js::ExclusiveContext::setCompartment(JSCompartment *comp)
{
    // ExclusiveContexts can only be in the atoms zone or in exclusive zones.
    MOZ_ASSERT_IF(!isJSContext() && !runtime_->isAtomsCompartment(comp),
                  comp->zone()->usedByExclusiveThread);

    // Normal JSContexts cannot enter exclusive zones.
    MOZ_ASSERT_IF(isJSContext() && comp,
                  !comp->zone()->usedByExclusiveThread);

    // Only one thread can be in the atoms compartment at a time.
    MOZ_ASSERT_IF(runtime_->isAtomsCompartment(comp),
                  runtime_->currentThreadHasExclusiveAccess());

    // Make sure that the atoms compartment has its own zone.
    MOZ_ASSERT_IF(comp && !runtime_->isAtomsCompartment(comp),
                  !runtime_->isAtomsZone(comp->zone()));

    // Both the current and the new compartment should be properly marked as
    // entered at this point.
    MOZ_ASSERT_IF(compartment_, compartment_->hasBeenEntered());
    MOZ_ASSERT_IF(comp, comp->hasBeenEntered());

    compartment_ = comp;
    zone_ = comp ? comp->zone() : nullptr;
    arenas_ = zone_ ? &zone_->arenas : nullptr;
}

inline JSScript *
JSContext::currentScript(jsbytecode **ppc,
                         MaybeAllowCrossCompartment allowCrossCompartment) const
{
    if (ppc)
        *ppc = nullptr;

    js::Activation *act = mainThread().activation();
    while (act && (act->cx() != this || (act->isJit() && !act->asJit()->isActive())))
        act = act->prev();

    if (!act)
        return nullptr;

    MOZ_ASSERT(act->cx() == this);

    if (act->isJit()) {
        JSScript *script = nullptr;
        js::jit::GetPcScript(const_cast<JSContext *>(this), &script, ppc);
        if (!allowCrossCompartment && script->compartment() != compartment())
            return nullptr;
        return script;
    }

    if (act->isAsmJS())
        return nullptr;

    MOZ_ASSERT(act->isInterpreter());

    js::InterpreterFrame *fp = act->asInterpreter()->current();
    MOZ_ASSERT(!fp->runningInJit());

    JSScript *script = fp->script();
    if (!allowCrossCompartment && script->compartment() != compartment())
        return nullptr;

    if (ppc) {
        *ppc = act->asInterpreter()->regs().pc;
        MOZ_ASSERT(script->containsPC(*ppc));
    }
    return script;
}

#endif /* jscntxtinlines_h */