Пример #1
0
void
LiveSavedFrameCache::find(JSContext* cx, FrameIter& frameIter, MutableHandleSavedFrame frame) const
{
    MOZ_ASSERT(initialized());
    MOZ_ASSERT(!frameIter.done());
    MOZ_ASSERT(frameIter.hasCachedSavedFrame());

    Maybe<FramePtr> maybeFramePtr = getFramePtr(frameIter);
    MOZ_ASSERT(maybeFramePtr.isSome());

    FramePtr framePtr(*maybeFramePtr);
    jsbytecode* pc = frameIter.pc();
    size_t numberStillValid = 0;

    frame.set(nullptr);
    for (auto* p = frames->begin(); p < frames->end(); p++) {
        numberStillValid++;
        if (framePtr == p->framePtr && pc == p->pc) {
            frame.set(p->savedFrame);
            break;
        }
    }

    if (!frame) {
        frames->clear();
        return;
    }

    MOZ_ASSERT(0 < numberStillValid && numberStillValid <= frames->length());

    if (frame->compartment() != cx->compartment()) {
        frame.set(nullptr);
        numberStillValid--;
    }

    // Everything after the cached SavedFrame are stale younger frames we have
    // since popped.
    frames->shrinkBy(frames->length() - numberStillValid);
}
Пример #2
0
bool
SavedStacks::insertFrames(JSContext *cx, FrameIter &iter, MutableHandleSavedFrame frame,
                          unsigned maxFrameCount)
{
    // In order to lookup a cached SavedFrame object, we need to have its parent
    // SavedFrame, which means we need to walk the stack from oldest frame to
    // youngest. However, FrameIter walks the stack from youngest frame to
    // oldest. The solution is to append stack frames to a vector as we walk the
    // stack with FrameIter, and then do a second pass through that vector in
    // reverse order after the traversal has completed and get or create the
    // SavedFrame objects at that time.
    //
    // To avoid making many copies of FrameIter (whose copy constructor is
    // relatively slow), we save the subset of FrameIter's data that is relevant
    // to our needs in a FrameState object, and maintain a vector of FrameState
    // objects instead of a vector of FrameIter objects.

    // Accumulate the vector of FrameState objects in |stackState|.
    AutoFrameStateVector stackState(cx);
    while (!iter.done()) {
        AutoLocationValueRooter location(cx);

        {
            AutoCompartment ac(cx, iter.compartment());
            if (!cx->compartment()->savedStacks().getLocation(cx, iter, &location))
                return false;
        }

        {
            FrameState frameState(iter);
            frameState.location = location.get();
            if (!stackState->append(frameState))
                return false;
        }

        ++iter;

        if (maxFrameCount == 0) {
            // If maxFrameCount is zero, then there's no limit on the number of
            // frames.
            continue;
        } else if (maxFrameCount == 1) {
            // Since we were only asked to save one frame, do not continue
            // walking the stack and saving frame state.
            break;
        } else {
            maxFrameCount--;
        }
    }

    // Iterate through |stackState| in reverse order and get or create the
    // actual SavedFrame instances.
    RootedSavedFrame parentFrame(cx, nullptr);
    for (size_t i = stackState->length(); i != 0; i--) {
        SavedFrame::AutoLookupRooter lookup(cx,
                                            stackState[i-1].location.source,
                                            stackState[i-1].location.line,
                                            stackState[i-1].location.column,
                                            stackState[i-1].name,
                                            parentFrame,
                                            stackState[i-1].principals);
        parentFrame.set(getOrCreateSavedFrame(cx, lookup));
        if (!parentFrame)
            return false;
    }

    frame.set(parentFrame);
    return true;
}
Пример #3
0
bool
SavedStacks::insertFrames(JSContext *cx, FrameIter &iter, MutableHandleSavedFrame frame,
                          unsigned maxFrameCount)
{
    if (iter.done()) {
        frame.set(nullptr);
        return true;
    }

    // Don't report the over-recursion error because if we are blowing the stack
    // here, we already blew the stack in JS, reported it, and we are creating
    // the saved stack for the over-recursion error object. We do this check
    // here, rather than inside saveCurrentStack, because in some cases we will
    // pass the check there, despite later failing the check here (for example,
    // in js/src/jit-test/tests/saved-stacks/bug-1006876-too-much-recursion.js).
    JS_CHECK_RECURSION_DONT_REPORT(cx, return false);

    JSPrincipals* principals = iter.compartment()->principals;
    RootedAtom name(cx, iter.isNonEvalFunctionFrame() ? iter.functionDisplayAtom() : nullptr);

    // When we have a |JSScript| for this frame, use |getLocation| to get a
    // potentially memoized location result and copy it into |location|. When we
    // do not have a |JSScript| for this frame (asm.js frames), we take a slow
    // path that doesn't employ memoization, and update |location|'s slots
    // directly.
    AutoLocationValueRooter location(cx);
    if (iter.hasScript()) {
        JSScript *script = iter.script();
        jsbytecode *pc = iter.pc();
        {
            AutoCompartment ac(cx, iter.compartment());
            if (!cx->compartment()->savedStacks().getLocation(cx, script, pc, &location))
                return false;
        }
    } else {
        const char *filename = iter.scriptFilename();
        if (!filename)
            filename = "";
        location.get().source = Atomize(cx, filename, strlen(filename));
        if (!location.get().source)
            return false;
        uint32_t column;
        location.get().line = iter.computeLine(&column);
        location.get().column = column;
    }

    RootedSavedFrame parentFrame(cx);

    // If maxFrameCount is zero, then there's no limit on the number of frames.
    if (maxFrameCount == 0) {
        if (!insertFrames(cx, ++iter, &parentFrame, 0))
            return false;
    } else if (maxFrameCount == 1) {
        // Since we were only asked to save one frame, the SavedFrame we're
        // building here should have no parent, even if there are older frames
        // on the stack.
        parentFrame = nullptr;
    } else {
        if (!insertFrames(cx, ++iter, &parentFrame, maxFrameCount - 1))
            return false;
    }

    SavedFrame::AutoLookupRooter lookup(cx,
                                        location.get().source,
                                        location.get().line,
                                        location.get().column,
                                        name,
                                        parentFrame,
                                        principals);

    frame.set(getOrCreateSavedFrame(cx, lookup));
    return frame.get() != nullptr;
}