src/third_party/WebKit/Source/JavaScriptCore/API/JSContextRef.cpp

/*
 * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#include "config.h"
#include "JSContextRef.h"
#include "JSContextRefPrivate.h"

#include "APICast.h"
#include "InitializeThreading.h"
#include <interpreter/CallFrame.h>
#include <interpreter/Interpreter.h>
#include "JSCallbackObject.h"
#include "JSClassRef.h"
#include "JSGlobalObject.h"
#include "JSObject.h"
#include <wtf/text/StringBuilder.h>
#include <wtf/text/StringHash.h>

#if OS(DARWIN)
#include <mach-o/dyld.h>

static const int32_t webkitFirstVersionWithConcurrentGlobalContexts = 0x2100500; // 528.5.0
#endif

using namespace JSC;

// From the API's perspective, a context group remains alive iff
//     (a) it has been JSContextGroupRetained
//     OR
//     (b) one of its contexts has been JSContextRetained

JSContextGroupRef JSContextGroupCreate()
{
    initializeThreading();
    return toRef(JSGlobalData::createContextGroup().leakRef());
}

JSContextGroupRef JSContextGroupRetain(JSContextGroupRef group)
{
    toJS(group)->ref();
    return group;
}

void JSContextGroupRelease(JSContextGroupRef group)
{
    toJS(group)->deref();
}

#if !defined(__LB_SHELL__) && !OS(STARBOARD)
// From the API's perspective, a global context remains alive iff it has been JSGlobalContextRetained.
JSGlobalContextRef JSGlobalContextCreate(JSClassRef globalObjectClass)
{
    initializeThreading();

#if OS(DARWIN)
    // If the application was linked before JSGlobalContextCreate was changed to use a unique JSGlobalData,
    // we use a shared one for backwards compatibility.
    if (NSVersionOfLinkTimeLibrary("JavaScriptCore") <= webkitFirstVersionWithConcurrentGlobalContexts) {
        return JSGlobalContextCreateInGroup(toRef(&JSGlobalData::sharedInstance()), globalObjectClass);
    }
#endif // OS(DARWIN)

    return JSGlobalContextCreateInGroup(0, globalObjectClass);
}

JSGlobalContextRef JSGlobalContextCreateInGroup(JSContextGroupRef group, JSClassRef globalObjectClass)
{
    initializeThreading();

    RefPtr<JSGlobalData> globalData = group ? PassRefPtr<JSGlobalData>(toJS(group)) : JSGlobalData::createContextGroup();

    APIEntryShim entryShim(globalData.get(), false);
    globalData->makeUsableFromMultipleThreads();

    if (!globalObjectClass) {
        JSGlobalObject* globalObject = JSGlobalObject::create(*globalData, JSGlobalObject::createStructure(*globalData, jsNull()));
        return JSGlobalContextRetain(toGlobalRef(globalObject->globalExec()));
    }

    JSGlobalObject* globalObject = JSCallbackObject<JSGlobalObject>::create(*globalData, globalObjectClass, JSCallbackObject<JSGlobalObject>::createStructure(*globalData, 0, jsNull()));
    ExecState* exec = globalObject->globalExec();
    JSValue prototype = globalObjectClass->prototype(exec);
    if (!prototype)
        prototype = jsNull();
    globalObject->resetPrototype(*globalData, prototype);
    return JSGlobalContextRetain(toGlobalRef(exec));
}
#endif

JSGlobalContextRef JSGlobalContextRetain(JSGlobalContextRef ctx)
{
    ExecState* exec = toJS(ctx);
    APIEntryShim entryShim(exec);

    JSGlobalData& globalData = exec->globalData();
    gcProtect(exec->dynamicGlobalObject());
    globalData.ref();
    return ctx;
}

void JSGlobalContextRelease(JSGlobalContextRef ctx)
{
    IdentifierTable* savedIdentifierTable;
    ExecState* exec = toJS(ctx);
    {
        JSLockHolder lock(exec);

        JSGlobalData& globalData = exec->globalData();
        savedIdentifierTable = wtfThreadData().setCurrentIdentifierTable(globalData.identifierTable);

        bool protectCountIsZero = Heap::heap(exec->dynamicGlobalObject())->unprotect(exec->dynamicGlobalObject());
        if (protectCountIsZero)
            globalData.heap.reportAbandonedObjectGraph();
        globalData.deref();
    }

    wtfThreadData().setCurrentIdentifierTable(savedIdentifierTable);
}

JSObjectRef JSContextGetGlobalObject(JSContextRef ctx)
{
    ExecState* exec = toJS(ctx);
    APIEntryShim entryShim(exec);

    // It is necessary to call toThisObject to get the wrapper object when used with WebCore.
    return toRef(exec->lexicalGlobalObject()->methodTable()->toThisObject(exec->lexicalGlobalObject(), exec));
}

JSContextGroupRef JSContextGetGroup(JSContextRef ctx)
{
    ExecState* exec = toJS(ctx);
    return toRef(&exec->globalData());
}

JSGlobalContextRef JSContextGetGlobalContext(JSContextRef ctx)
{
    ExecState* exec = toJS(ctx);
    APIEntryShim entryShim(exec);

    return toGlobalRef(exec->lexicalGlobalObject()->globalExec());
}
    
JSStringRef JSContextCreateBacktrace(JSContextRef ctx, unsigned maxStackSize)
{
    ExecState* exec = toJS(ctx);
    JSLockHolder lock(exec);

    unsigned count = 0;
    StringBuilder builder;
    CallFrame* callFrame = exec;
    String functionName;
    if (exec->callee()) {
        if (asObject(exec->callee())->inherits(InternalFunction::s_classinfo())) {
            functionName = asInternalFunction(exec->callee())->name(exec);
            builder.appendLiteral("#0 ");
            builder.append(functionName);
            builder.appendLiteral("() ");
            count++;
        }
    }
    while (true) {
        ASSERT(callFrame);
        int signedLineNumber;
        intptr_t sourceID;
        String urlString;
        JSValue function;

        exec->interpreter()->retrieveLastCaller(callFrame, signedLineNumber, sourceID, urlString, function);

        if (function)
            functionName = jsCast<JSFunction*>(function)->name(exec);
        else {
            // Caller is unknown, but if frame is empty we should still add the frame, because
            // something called us, and gave us arguments.
            if (count)
                break;
        }
        unsigned lineNumber = signedLineNumber >= 0 ? signedLineNumber : 0;
        if (!builder.isEmpty())
            builder.append('\n');
        builder.append('#');
        builder.appendNumber(count);
        builder.append(' ');
        builder.append(functionName);
        builder.appendLiteral("() at ");
        builder.append(urlString);
        builder.append(':');
        builder.appendNumber(lineNumber);
        if (!function || ++count == maxStackSize)
            break;
        callFrame = callFrame->callerFrame();
    }
    return OpaqueJSString::create(builder.toString()).leakRef();
}