The Tor Browser: js/src/jsfun.cpp@6474c204b198 (annotated)

js/src/jsfun.cpp@6474c204b198 (annotated)

js/src/jsfun.cpp

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- 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/. */
 /*
  * JS function support.
  */
 #include "jsfuninlines.h"
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/PodOperations.h"
 #include <string.h>
 #include "jsapi.h"
 #include "jsarray.h"
 #include "jsatom.h"
 #include "jscntxt.h"
 #include "jsobj.h"
 #include "jsproxy.h"
 #include "jsscript.h"
 #include "jsstr.h"
 #include "jstypes.h"
 #include "jswrapper.h"
 #include "builtin/Eval.h"
 #include "builtin/Object.h"
 #include "frontend/BytecodeCompiler.h"
 #include "frontend/TokenStream.h"
 #include "gc/Marking.h"
 #ifdef JS_ION
 #include "jit/Ion.h"
 #include "jit/JitFrameIterator.h"
 #endif
 #include "vm/Interpreter.h"
 #include "vm/Shape.h"
 #include "vm/StringBuffer.h"
 #include "vm/WrapperObject.h"
 #include "vm/Xdr.h"
 #include "jsscriptinlines.h"
 #include "vm/Interpreter-inl.h"
 #include "vm/Stack-inl.h"
 using namespace js;
 using namespace js::gc;
 using namespace js::types;
 using namespace js::frontend;
 using mozilla::ArrayLength;
 using mozilla::PodCopy;
 static bool
 fun_getProperty(JSContext *cx, HandleObject obj_, HandleId id, MutableHandleValue vp)
 {
     RootedObject obj(cx, obj_);
     while (!obj->is<JSFunction>()) {
         if (!JSObject::getProto(cx, obj, &obj))
             return false;
         if (!obj)
             return true;
     }
     RootedFunction fun(cx, &obj->as<JSFunction>());
     /* Set to early to null in case of error */
     vp.setNull();
     /* Find fun's top-most activation record. */
     NonBuiltinScriptFrameIter iter(cx);
     for (; !iter.done(); ++iter) {
         if (!iter.isFunctionFrame() || iter.isEvalFrame())
             continue;
         if (iter.callee() == fun)
             break;
     }
     if (iter.done())
         return true;
     if (JSID_IS_ATOM(id, cx->names().arguments)) {
         if (fun->hasRest()) {
             JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr,
                                  JSMSG_FUNCTION_ARGUMENTS_AND_REST);
             return false;
         }
         /* Warn if strict about f.arguments or equivalent unqualified uses. */
         if (!JS_ReportErrorFlagsAndNumber(cx, JSREPORT_WARNING | JSREPORT_STRICT, js_GetErrorMessage,
                                           nullptr, JSMSG_DEPRECATED_USAGE, js_arguments_str)) {
             return false;
         }
         ArgumentsObject *argsobj = ArgumentsObject::createUnexpected(cx, iter);
         if (!argsobj)
             return false;
 #ifdef JS_ION
         // Disabling compiling of this script in IonMonkey.
         // IonMonkey does not guarantee |f.arguments| can be
         // fully recovered, so we try to mitigate observing this behavior by
         // detecting its use early.
         JSScript *script = iter.script();
         jit::ForbidCompilation(cx, script);
 #endif
         vp.setObject(*argsobj);
         return true;
     }
     if (JSID_IS_ATOM(id, cx->names().caller)) {
         ++iter;
         if (iter.done() || !iter.isFunctionFrame()) {
             JS_ASSERT(vp.isNull());
             return true;
         }
         /* Callsite clones should never escape to script. */
         JSObject &maybeClone = iter.calleev().toObject();
         if (maybeClone.is<JSFunction>())
             vp.setObject(*maybeClone.as<JSFunction>().originalFunction());
         else
             vp.set(iter.calleev());
         if (!cx->compartment()->wrap(cx, vp))
             return false;
         /*
          * Censor the caller if we don't have full access to it.
          */
         RootedObject caller(cx, &vp.toObject());
         if (caller->is<WrapperObject>() && Wrapper::wrapperHandler(caller)->hasSecurityPolicy()) {
             vp.setNull();
         } else if (caller->is<JSFunction>()) {
             JSFunction *callerFun = &caller->as<JSFunction>();
             if (callerFun->isInterpreted() && callerFun->strict()) {
                 JS_ReportErrorFlagsAndNumber(cx, JSREPORT_ERROR, js_GetErrorMessage, nullptr,
                                              JSMSG_CALLER_IS_STRICT);
                 return false;
             }
         }
         return true;
     }
     MOZ_ASSUME_UNREACHABLE("fun_getProperty");
 }
 /* NB: no sentinels at ends -- use ArrayLength to bound loops.
  * Properties censored into [[ThrowTypeError]] in strict mode. */
 static const uint16_t poisonPillProps[] = {
     NAME_OFFSET(arguments),
     NAME_OFFSET(caller),
 };
 static bool
 fun_enumerate(JSContext *cx, HandleObject obj)
 {
     JS_ASSERT(obj->is<JSFunction>());
     RootedId id(cx);
     bool found;
     if (!obj->isBoundFunction() && !obj->as<JSFunction>().isArrow()) {
         id = NameToId(cx->names().prototype);
         if (!JSObject::hasProperty(cx, obj, id, &found))
             return false;
     }
     id = NameToId(cx->names().length);
     if (!JSObject::hasProperty(cx, obj, id, &found))
         return false;
     id = NameToId(cx->names().name);
     if (!JSObject::hasProperty(cx, obj, id, &found))
         return false;
     for (unsigned i = 0; i < ArrayLength(poisonPillProps); i++) {
         const uint16_t offset = poisonPillProps[i];
         id = NameToId(AtomStateOffsetToName(cx->names(), offset));
         if (!JSObject::hasProperty(cx, obj, id, &found))
             return false;
     }
     return true;
 }
 static JSObject *
 ResolveInterpretedFunctionPrototype(JSContext *cx, HandleObject obj)
 {
 #ifdef DEBUG
     JSFunction *fun = &obj->as<JSFunction>();
     JS_ASSERT(fun->isInterpreted());
     JS_ASSERT(!fun->isFunctionPrototype());
 #endif
     // Assert that fun is not a compiler-created function object, which
     // must never leak to script or embedding code and then be mutated.
     // Also assert that obj is not bound, per the ES5 15.3.4.5 ref above.
     JS_ASSERT(!IsInternalFunctionObject(obj));
     JS_ASSERT(!obj->isBoundFunction());
     // Make the prototype object an instance of Object with the same parent as
     // the function object itself, unless the function is an ES6 generator.  In
     // that case, per the 15 July 2013 ES6 draft, section 15.19.3, its parent is
     // the GeneratorObjectPrototype singleton.
     bool isStarGenerator = obj->as<JSFunction>().isStarGenerator();
     Rooted<GlobalObject*> global(cx, &obj->global());
     JSObject *objProto;
     if (isStarGenerator)
         objProto = GlobalObject::getOrCreateStarGeneratorObjectPrototype(cx, global);
     else
         objProto = obj->global().getOrCreateObjectPrototype(cx);
     if (!objProto)
         return nullptr;
     const Class *clasp = &JSObject::class_;
     RootedObject proto(cx, NewObjectWithGivenProto(cx, clasp, objProto, nullptr, SingletonObject));
     if (!proto)
         return nullptr;
     // Per ES5 15.3.5.2 a user-defined function's .prototype property is
     // initially non-configurable, non-enumerable, and writable.
     RootedValue protoVal(cx, ObjectValue(*proto));
     if (!JSObject::defineProperty(cx, obj, cx->names().prototype,
                                   protoVal, JS_PropertyStub, JS_StrictPropertyStub,
                                   JSPROP_PERMANENT))
     {
         return nullptr;
     }
     // Per ES5 13.2 the prototype's .constructor property is configurable,
     // non-enumerable, and writable.  However, per the 15 July 2013 ES6 draft,
     // section 15.19.3, the .prototype of a generator function does not link
     // back with a .constructor.
     if (!isStarGenerator) {
         RootedValue objVal(cx, ObjectValue(*obj));
         if (!JSObject::defineProperty(cx, proto, cx->names().constructor,
                                       objVal, JS_PropertyStub, JS_StrictPropertyStub, 0))
         {
             return nullptr;
         }
     }
     return proto;
 }
 bool
 js::FunctionHasResolveHook(const JSAtomState &atomState, PropertyName *name)
 {
     if (name == atomState.prototype || name == atomState.length || name == atomState.name)
         return true;
     for (unsigned i = 0; i < ArrayLength(poisonPillProps); i++) {
         const uint16_t offset = poisonPillProps[i];
         if (name == AtomStateOffsetToName(atomState, offset))
             return true;
     }
     return false;
 }
 bool
 js::fun_resolve(JSContext *cx, HandleObject obj, HandleId id, MutableHandleObject objp)
 {
     if (!JSID_IS_ATOM(id))
         return true;
     RootedFunction fun(cx, &obj->as<JSFunction>());
     if (JSID_IS_ATOM(id, cx->names().prototype)) {
         /*
          * Built-in functions do not have a .prototype property per ECMA-262,
          * or (Object.prototype, Function.prototype, etc.) have that property
          * created eagerly.
          *
          * ES5 15.3.4: the non-native function object named Function.prototype
          * does not have a .prototype property.
          *
          * ES5 15.3.4.5: bound functions don't have a prototype property. The
          * isBuiltin() test covers this case because bound functions are native
          * (and thus built-in) functions by definition/construction.
          *
          * ES6 19.2.4.3: arrow functions also don't have a prototype property.
          */
         if (fun->isBuiltin() || fun->isArrow() || fun->isFunctionPrototype())
             return true;
         if (!ResolveInterpretedFunctionPrototype(cx, fun))
             return false;
         objp.set(fun);
         return true;
     }
     if (JSID_IS_ATOM(id, cx->names().length) || JSID_IS_ATOM(id, cx->names().name)) {
         JS_ASSERT(!IsInternalFunctionObject(obj));
         RootedValue v(cx);
         if (JSID_IS_ATOM(id, cx->names().length)) {
             if (fun->isInterpretedLazy() && !fun->getOrCreateScript(cx))
                 return false;
             uint16_t length = fun->hasScript() ? fun->nonLazyScript()->funLength() :
                 fun->nargs() - fun->hasRest();
             v.setInt32(length);
         } else {
             v.setString(fun->atom() == nullptr ? cx->runtime()->emptyString : fun->atom());
         }
         if (!DefineNativeProperty(cx, fun, id, v, JS_PropertyStub, JS_StrictPropertyStub,
                                   JSPROP_PERMANENT | JSPROP_READONLY)) {
             return false;
         }
         objp.set(fun);
         return true;
     }
     for (unsigned i = 0; i < ArrayLength(poisonPillProps); i++) {
         const uint16_t offset = poisonPillProps[i];
         if (JSID_IS_ATOM(id, AtomStateOffsetToName(cx->names(), offset))) {
             JS_ASSERT(!IsInternalFunctionObject(fun));
             PropertyOp getter;
             StrictPropertyOp setter;
             unsigned attrs = JSPROP_PERMANENT | JSPROP_SHARED;
             if (fun->isInterpretedLazy() && !fun->getOrCreateScript(cx))
                 return false;
             if (fun->isInterpreted() ? fun->strict() : fun->isBoundFunction()) {
                 JSObject *throwTypeError = fun->global().getThrowTypeError();
                 getter = CastAsPropertyOp(throwTypeError);
                 setter = CastAsStrictPropertyOp(throwTypeError);
                 attrs |= JSPROP_GETTER | JSPROP_SETTER;
             } else {
                 getter = fun_getProperty;
                 setter = JS_StrictPropertyStub;
             }
             if (!DefineNativeProperty(cx, fun, id, UndefinedHandleValue, getter, setter, attrs))
                 return false;
             objp.set(fun);
             return true;
         }
     }
     return true;
 }
 template<XDRMode mode>
 bool
 js::XDRInterpretedFunction(XDRState<mode> *xdr, HandleObject enclosingScope, HandleScript enclosingScript,
                            MutableHandleObject objp)
 {
     enum FirstWordFlag {
         HasAtom             = 0x1,
         IsStarGenerator     = 0x2,
         IsLazy              = 0x4,
         HasSingletonType    = 0x8
     };
     /* NB: Keep this in sync with CloneFunctionAndScript. */
     RootedAtom atom(xdr->cx());
     uint32_t firstword = 0;        /* bitmask of FirstWordFlag */
     uint32_t flagsword = 0;        /* word for argument count and fun->flags */
     JSContext *cx = xdr->cx();
     RootedFunction fun(cx);
     RootedScript script(cx);
     Rooted<LazyScript *> lazy(cx);
     if (mode == XDR_ENCODE) {
         fun = &objp->as<JSFunction>();
         if (!fun->isInterpreted()) {
             JSAutoByteString funNameBytes;
             if (const char *name = GetFunctionNameBytes(cx, fun, &funNameBytes)) {
                 JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr,
                                      JSMSG_NOT_SCRIPTED_FUNCTION, name);
             }
             return false;
         }
         if (fun->atom() || fun->hasGuessedAtom())
             firstword |= HasAtom;
         if (fun->isStarGenerator())
             firstword |= IsStarGenerator;
         if (fun->isInterpretedLazy()) {
             // This can only happen for re-lazified cloned functions, so this
             // does not apply to any JSFunction produced by the parser, only to
             // JSFunction created by the runtime.
             JS_ASSERT(!fun->lazyScript()->maybeScript());
             // Encode a lazy script.
             firstword |= IsLazy;
             lazy = fun->lazyScript();
         } else {
             // Encode the script.
             script = fun->nonLazyScript();
         }
         if (fun->hasSingletonType())
             firstword |= HasSingletonType;
         atom = fun->displayAtom();
         flagsword = (fun->nargs() << 16) | fun->flags();
         // The environment of any function which is not reused will always be
         // null, it is later defined when a function is cloned or reused to
         // mirror the scope chain.
         JS_ASSERT_IF(fun->hasSingletonType() &&
                      !((lazy && lazy->hasBeenCloned()) || (script && script->hasBeenCloned())),
                      fun->environment() == nullptr);
     }
     if (!xdr->codeUint32(&firstword))
         return false;
     if ((firstword & HasAtom) && !XDRAtom(xdr, &atom))
         return false;
     if (!xdr->codeUint32(&flagsword))
         return false;
     if (mode == XDR_DECODE) {
         JSObject *proto = nullptr;
         if (firstword & IsStarGenerator) {
             proto = GlobalObject::getOrCreateStarGeneratorFunctionPrototype(cx, cx->global());
             if (!proto)
                 return false;
         }
         gc::AllocKind allocKind = JSFunction::FinalizeKind;
         if (uint16_t(flagsword) & JSFunction::EXTENDED)
             allocKind = JSFunction::ExtendedFinalizeKind;
         fun = NewFunctionWithProto(cx, NullPtr(), nullptr, 0, JSFunction::INTERPRETED,
                                    /* parent = */ NullPtr(), NullPtr(), proto,
                                    allocKind, TenuredObject);
         if (!fun)
             return false;
         script = nullptr;
     }
     if (firstword & IsLazy) {
         if (!XDRLazyScript(xdr, enclosingScope, enclosingScript, fun, &lazy))
             return false;
     } else {
         if (!XDRScript(xdr, enclosingScope, enclosingScript, fun, &script))
             return false;
     }
     if (mode == XDR_DECODE) {
         fun->setArgCount(flagsword >> 16);
         fun->setFlags(uint16_t(flagsword));
         fun->initAtom(atom);
         if (firstword & IsLazy) {
             fun->initLazyScript(lazy);
         } else {
             fun->initScript(script);
             script->setFunction(fun);
             JS_ASSERT(fun->nargs() == script->bindings.numArgs());
         }
         bool singleton = firstword & HasSingletonType;
         if (!JSFunction::setTypeForScriptedFunction(cx, fun, singleton))
             return false;
         objp.set(fun);
     }
     return true;
 }
 template bool
 js::XDRInterpretedFunction(XDRState<XDR_ENCODE> *, HandleObject, HandleScript, MutableHandleObject);
 template bool
 js::XDRInterpretedFunction(XDRState<XDR_DECODE> *, HandleObject, HandleScript, MutableHandleObject);
 JSObject *
 js::CloneFunctionAndScript(JSContext *cx, HandleObject enclosingScope, HandleFunction srcFun)
 {
     /* NB: Keep this in sync with XDRInterpretedFunction. */
     JSObject *cloneProto = nullptr;
     if (srcFun->isStarGenerator()) {
         cloneProto = GlobalObject::getOrCreateStarGeneratorFunctionPrototype(cx, cx->global());
         if (!cloneProto)
             return nullptr;
     }
     gc::AllocKind allocKind = JSFunction::FinalizeKind;
     if (srcFun->isExtended())
         allocKind = JSFunction::ExtendedFinalizeKind;
     RootedFunction clone(cx, NewFunctionWithProto(cx, NullPtr(), nullptr, 0,
                                                   JSFunction::INTERPRETED, NullPtr(), NullPtr(),
                                                   cloneProto, allocKind, TenuredObject));
     if (!clone)
         return nullptr;
     RootedScript srcScript(cx, srcFun->getOrCreateScript(cx));
     if (!srcScript)
         return nullptr;
     RootedScript clonedScript(cx, CloneScript(cx, enclosingScope, clone, srcScript));
     if (!clonedScript)
         return nullptr;
     clone->setArgCount(srcFun->nargs());
     clone->setFlags(srcFun->flags());
     clone->initAtom(srcFun->displayAtom());
     clone->initScript(clonedScript);
     clonedScript->setFunction(clone);
     if (!JSFunction::setTypeForScriptedFunction(cx, clone))
         return nullptr;
     RootedScript cloneScript(cx, clone->nonLazyScript());
     CallNewScriptHook(cx, cloneScript, clone);
     return clone;
 }
 /*
  * [[HasInstance]] internal method for Function objects: fetch the .prototype
  * property of its 'this' parameter, and walks the prototype chain of v (only
  * if v is an object) returning true if .prototype is found.
  */
 static bool
 fun_hasInstance(JSContext *cx, HandleObject objArg, MutableHandleValue v, bool *bp)
 {
     RootedObject obj(cx, objArg);
     while (obj->is<JSFunction>() && obj->isBoundFunction())
         obj = obj->as<JSFunction>().getBoundFunctionTarget();
     RootedValue pval(cx);
     if (!JSObject::getProperty(cx, obj, obj, cx->names().prototype, &pval))
         return false;
     if (pval.isPrimitive()) {
         /*
          * Throw a runtime error if instanceof is called on a function that
          * has a non-object as its .prototype value.
          */
         RootedValue val(cx, ObjectValue(*obj));
         js_ReportValueError(cx, JSMSG_BAD_PROTOTYPE, -1, val, js::NullPtr());
         return false;
     }
     RootedObject pobj(cx, &pval.toObject());
     bool isDelegate;
     if (!IsDelegate(cx, pobj, v, &isDelegate))
         return false;
     *bp = isDelegate;
     return true;
 }
 inline void
 JSFunction::trace(JSTracer *trc)
 {
     if (isExtended()) {
         MarkValueRange(trc, ArrayLength(toExtended()->extendedSlots),
                        toExtended()->extendedSlots, "nativeReserved");
     }
     if (atom_)
         MarkString(trc, &atom_, "atom");
     if (isInterpreted()) {
         // Functions can be be marked as interpreted despite having no script
         // yet at some points when parsing, and can be lazy with no lazy script
         // for self-hosted code.
         if (hasScript() && u.i.s.script_) {
             // Functions can be relazified under the following conditions:
             // - their compartment isn't currently executing scripts or being
             //   debugged
             // - they are not in the self-hosting compartment
             // - they aren't generators
             // - they don't have JIT code attached
             // - they haven't ever been inlined
             // - they don't have child functions
             // - they have information for un-lazifying them again later
             // This information can either be a LazyScript, or the name of a
             // self-hosted function which can be cloned over again. The latter
             // is stored in the first extended slot.
             if (IS_GC_MARKING_TRACER(trc) && !compartment()->hasBeenEntered() &&
                 !compartment()->debugMode() && !compartment()->isSelfHosting &&
                 u.i.s.script_->isRelazifiable() && (!isSelfHostedBuiltin() || isExtended()))
             {
                 relazify(trc);
             } else {
                 MarkScriptUnbarriered(trc, &u.i.s.script_, "script");
             }
         } else if (isInterpretedLazy() && u.i.s.lazy_) {
             MarkLazyScriptUnbarriered(trc, &u.i.s.lazy_, "lazyScript");
         }
         if (u.i.env_)
             MarkObjectUnbarriered(trc, &u.i.env_, "fun_callscope");
     }
 }
 static void
 fun_trace(JSTracer *trc, JSObject *obj)
 {
     obj->as<JSFunction>().trace(trc);
 }
 const Class JSFunction::class_ = {
     js_Function_str,
     JSCLASS_NEW_RESOLVE | JSCLASS_IMPLEMENTS_BARRIERS |
     JSCLASS_HAS_CACHED_PROTO(JSProto_Function),
     JS_PropertyStub,         /* addProperty */
     JS_DeletePropertyStub,   /* delProperty */
     JS_PropertyStub,         /* getProperty */
     JS_StrictPropertyStub,   /* setProperty */
     fun_enumerate,
     (JSResolveOp)js::fun_resolve,
     JS_ConvertStub,
     nullptr,                 /* finalize    */
     nullptr,                 /* call        */
     fun_hasInstance,
     nullptr,                 /* construct   */
     fun_trace
 };
 const Class* const js::FunctionClassPtr = &JSFunction::class_;
 /* Find the body of a function (not including braces). */
 bool
 js::FindBody(JSContext *cx, HandleFunction fun, ConstTwoByteChars chars, size_t length,
          size_t *bodyStart, size_t *bodyEnd)
 {
     // We don't need principals, since those are only used for error reporting.
     CompileOptions options(cx);
     options.setFileAndLine("internal-findBody", 0);
     // For asm.js modules, there's no script.
     if (fun->hasScript())
         options.setVersion(fun->nonLazyScript()->getVersion());
     AutoKeepAtoms keepAtoms(cx->perThreadData);
     TokenStream ts(cx, options, chars.get(), length, nullptr);
     int nest = 0;
     bool onward = true;
     // Skip arguments list.
     do {
         switch (ts.getToken()) {
           case TOK_NAME:
           case TOK_YIELD:
             if (nest == 0)
                 onward = false;
             break;
           case TOK_LP:
             nest++;
             break;
           case TOK_RP:
             if (--nest == 0)
                 onward = false;
             break;
           case TOK_ERROR:
             // Must be memory.
             return false;
           default:
             break;
         }
     } while (onward);
     TokenKind tt = ts.getToken();
     if (tt == TOK_ARROW)
         tt = ts.getToken();
     if (tt == TOK_ERROR)
         return false;
     bool braced = tt == TOK_LC;
     JS_ASSERT_IF(fun->isExprClosure(), !braced);
     *bodyStart = ts.currentToken().pos.begin;
     if (braced)
         *bodyStart += 1;
     ConstTwoByteChars end(chars.get() + length, chars.get(), length);
     if (end[-1] == '}') {
         end--;
     } else {
         JS_ASSERT(!braced);
         for (; unicode::IsSpaceOrBOM2(end[-1]); end--)
             ;
     }
     *bodyEnd = end - chars;
     JS_ASSERT(*bodyStart <= *bodyEnd);
     return true;
 }
 JSString *
 js::FunctionToString(JSContext *cx, HandleFunction fun, bool bodyOnly, bool lambdaParen)
 {
     if (fun->isInterpretedLazy() && !fun->getOrCreateScript(cx))
         return nullptr;
     if (IsAsmJSModule(fun))
         return AsmJSModuleToString(cx, fun, !lambdaParen);
     if (IsAsmJSFunction(fun))
         return AsmJSFunctionToString(cx, fun);
     StringBuffer out(cx);
     RootedScript script(cx);
     if (fun->hasScript()) {
         script = fun->nonLazyScript();
         if (script->isGeneratorExp()) {
             if ((!bodyOnly && !out.append("function genexp() {")) ||
                 !out.append("\n    [generator expression]\n") ||
                 (!bodyOnly && !out.append("}")))
             {
                 return nullptr;
             }
             return out.finishString();
         }
     }
     if (!bodyOnly) {
         // If we're not in pretty mode, put parentheses around lambda functions.
         if (fun->isInterpreted() && !lambdaParen && fun->isLambda() && !fun->isArrow()) {
             if (!out.append("("))
                 return nullptr;
         }
         if (!fun->isArrow()) {
             if (!(fun->isStarGenerator() ? out.append("function* ") : out.append("function ")))
                 return nullptr;
         }
         if (fun->atom()) {
             if (!out.append(fun->atom()))
                 return nullptr;
         }
     }
     bool haveSource = fun->isInterpreted() && !fun->isSelfHostedBuiltin();
     if (haveSource && !script->scriptSource()->hasSourceData() &&
         !JSScript::loadSource(cx, script->scriptSource(), &haveSource))
     {
         return nullptr;
     }
     if (haveSource) {
         RootedString srcStr(cx, script->sourceData(cx));
         if (!srcStr)
             return nullptr;
         Rooted<JSFlatString *> src(cx, srcStr->ensureFlat(cx));
         if (!src)
             return nullptr;
         ConstTwoByteChars chars(src->chars(), src->length());
         bool exprBody = fun->isExprClosure();
         // The source data for functions created by calling the Function
         // constructor is only the function's body.  This depends on the fact,
         // asserted below, that in Function("function f() {}"), the inner
         // function's sourceStart points to the '(', not the 'f'.
         bool funCon = !fun->isArrow() &&
                       script->sourceStart() == 0 &&
                       script->sourceEnd() == script->scriptSource()->length() &&
                       script->scriptSource()->argumentsNotIncluded();
         // Functions created with the constructor can't be arrow functions or
         // expression closures.
         JS_ASSERT_IF(funCon, !fun->isArrow());
         JS_ASSERT_IF(funCon, !exprBody);
         JS_ASSERT_IF(!funCon && !fun->isArrow(), src->length() > 0 && chars[0] == '(');
         // If a function inherits strict mode by having scopes above it that
         // have "use strict", we insert "use strict" into the body of the
         // function. This ensures that if the result of toString is evaled, the
         // resulting function will have the same semantics.
         bool addUseStrict = script->strict() && !script->explicitUseStrict() && !fun->isArrow();
         bool buildBody = funCon && !bodyOnly;
         if (buildBody) {
             // This function was created with the Function constructor. We don't
             // have source for the arguments, so we have to generate that. Part
             // of bug 755821 should be cobbling the arguments passed into the
             // Function constructor into the source string.
             if (!out.append("("))
                 return nullptr;
             // Fish out the argument names.
             BindingVector *localNames = cx->new_<BindingVector>(cx);
             ScopedJSDeletePtr<BindingVector> freeNames(localNames);
             if (!FillBindingVector(script, localNames))
                 return nullptr;
             for (unsigned i = 0; i < fun->nargs(); i++) {
                 if ((i && !out.append(", ")) ||
                     (i == unsigned(fun->nargs() - 1) && fun->hasRest() && !out.append("...")) ||
                     !out.append((*localNames)[i].name())) {
                     return nullptr;
                 }
             }
             if (!out.append(") {\n"))
                 return nullptr;
         }
         if ((bodyOnly && !funCon) || addUseStrict) {
             // We need to get at the body either because we're only supposed to
             // return the body or we need to insert "use strict" into the body.
             size_t bodyStart = 0, bodyEnd;
             // If the function is defined in the Function constructor, we
             // already have a body.
             if (!funCon) {
                 JS_ASSERT(!buildBody);
                 if (!FindBody(cx, fun, chars, src->length(), &bodyStart, &bodyEnd))
                     return nullptr;
             } else {
                 bodyEnd = src->length();
             }
             if (addUseStrict) {
                 // Output source up to beginning of body.
                 if (!out.append(chars, bodyStart))
                     return nullptr;
                 if (exprBody) {
                     // We can't insert a statement into a function with an
                     // expression body. Do what the decompiler did, and insert a
                     // comment.
                     if (!out.append("/* use strict */ "))
                         return nullptr;
                 } else {
                     if (!out.append("\n\"use strict\";\n"))
                         return nullptr;
                 }
             }
             // Output just the body (for bodyOnly) or the body and possibly
             // closing braces (for addUseStrict).
             size_t dependentEnd = bodyOnly ? bodyEnd : src->length();
             if (!out.append(chars + bodyStart, dependentEnd - bodyStart))
                 return nullptr;
         } else {
             if (!out.append(src))
                 return nullptr;
         }
         if (buildBody) {
             if (!out.append("\n}"))
                 return nullptr;
         }
         if (bodyOnly) {
             // Slap a semicolon on the end of functions with an expression body.
             if (exprBody && !out.append(";"))
                 return nullptr;
         } else if (!lambdaParen && fun->isLambda() && !fun->isArrow()) {
             if (!out.append(")"))
                 return nullptr;
         }
     } else if (fun->isInterpreted() && !fun->isSelfHostedBuiltin()) {
         if ((!bodyOnly && !out.append("() {\n    ")) ||
             !out.append("[sourceless code]") ||
             (!bodyOnly && !out.append("\n}")))
             return nullptr;
         if (!lambdaParen && fun->isLambda() && !fun->isArrow() && !out.append(")"))
             return nullptr;
     } else {
         JS_ASSERT(!fun->isExprClosure());
         if ((!bodyOnly && !out.append("() {\n    "))
             || !out.append("[native code]")
             || (!bodyOnly && !out.append("\n}")))
         {
             return nullptr;
         }
     }
     return out.finishString();
 }
 JSString *
 fun_toStringHelper(JSContext *cx, HandleObject obj, unsigned indent)
 {
     if (!obj->is<JSFunction>()) {
         if (obj->is<ProxyObject>())
             return Proxy::fun_toString(cx, obj, indent);
         JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr,
                              JSMSG_INCOMPATIBLE_PROTO,
                              js_Function_str, js_toString_str,
                              "object");
         return nullptr;
     }
     RootedFunction fun(cx, &obj->as<JSFunction>());
     return FunctionToString(cx, fun, false, indent != JS_DONT_PRETTY_PRINT);
 }
 static bool
 fun_toString(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     JS_ASSERT(IsFunctionObject(args.calleev()));
     uint32_t indent = 0;
     if (args.length() != 0 && !ToUint32(cx, args[0], &indent))
         return false;
     RootedObject obj(cx, ToObject(cx, args.thisv()));
     if (!obj)
         return false;
     RootedString str(cx, fun_toStringHelper(cx, obj, indent));
     if (!str)
         return false;
     args.rval().setString(str);
     return true;
 }
 #if JS_HAS_TOSOURCE
 static bool
 fun_toSource(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     JS_ASSERT(IsFunctionObject(args.calleev()));
     RootedObject obj(cx, ToObject(cx, args.thisv()));
     if (!obj)
         return false;
     RootedString str(cx);
     if (obj->isCallable())
         str = fun_toStringHelper(cx, obj, JS_DONT_PRETTY_PRINT);
     else
         str = ObjectToSource(cx, obj);
     if (!str)
         return false;
     args.rval().setString(str);
     return true;
 }
 #endif
 bool
 js_fun_call(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     HandleValue fval = args.thisv();
     if (!js_IsCallable(fval)) {
         ReportIncompatibleMethod(cx, args, &JSFunction::class_);
         return false;
     }
     args.setCallee(fval);
     args.setThis(args.get(0));
     if (args.length() > 0) {
         for (size_t i = 0; i < args.length() - 1; i++)
             args[i].set(args[i + 1]);
         args = CallArgsFromVp(args.length() - 1, vp);
     }
     return Invoke(cx, args);
 }
 // ES5 15.3.4.3
 bool
 js_fun_apply(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     // Step 1.
     HandleValue fval = args.thisv();
     if (!js_IsCallable(fval)) {
         ReportIncompatibleMethod(cx, args, &JSFunction::class_);
         return false;
     }
     // Step 2.
     if (args.length() < 2 || args[1].isNullOrUndefined())
         return js_fun_call(cx, (args.length() > 0) ? 1 : 0, vp);
     InvokeArgs args2(cx);
     // A JS_OPTIMIZED_ARGUMENTS magic value means that 'arguments' flows into
     // this apply call from a scripted caller and, as an optimization, we've
     // avoided creating it since apply can simply pull the argument values from
     // the calling frame (which we must do now).
     if (args[1].isMagic(JS_OPTIMIZED_ARGUMENTS)) {
         // Step 3-6.
         ScriptFrameIter iter(cx);
         JS_ASSERT(iter.numActualArgs() <= ARGS_LENGTH_MAX);
         if (!args2.init(iter.numActualArgs()))
             return false;
         args2.setCallee(fval);
         args2.setThis(args[0]);
         // Steps 7-8.
         iter.unaliasedForEachActual(cx, CopyTo(args2.array()));
     } else {
         // Step 3.
         if (!args[1].isObject()) {
             JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr,
                                  JSMSG_BAD_APPLY_ARGS, js_apply_str);
             return false;
         }
         // Steps 4-5 (note erratum removing steps originally numbered 5 and 7 in
         // original version of ES5).
         RootedObject aobj(cx, &args[1].toObject());
         uint32_t length;
         if (!GetLengthProperty(cx, aobj, &length))
             return false;
         // Step 6.
         if (length > ARGS_LENGTH_MAX) {
             JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr, JSMSG_TOO_MANY_FUN_APPLY_ARGS);
             return false;
         }
         if (!args2.init(length))
             return false;
         // Push fval, obj, and aobj's elements as args.
         args2.setCallee(fval);
         args2.setThis(args[0]);
         // Steps 7-8.
         if (!GetElements(cx, aobj, length, args2.array()))
             return false;
     }
     // Step 9.
     if (!Invoke(cx, args2))
         return false;
     args.rval().set(args2.rval());
     return true;
 }
 static const uint32_t JSSLOT_BOUND_FUNCTION_THIS       = 0;
 static const uint32_t JSSLOT_BOUND_FUNCTION_ARGS_COUNT = 1;
 static const uint32_t BOUND_FUNCTION_RESERVED_SLOTS = 2;
 inline bool
 JSFunction::initBoundFunction(JSContext *cx, HandleValue thisArg,
                               const Value *args, unsigned argslen)
 {
     RootedFunction self(cx, this);
     /*
      * Convert to a dictionary to set the BOUND_FUNCTION flag and increase
      * the slot span to cover the arguments and additional slots for the 'this'
      * value and arguments count.
      */
     if (!self->toDictionaryMode(cx))
         return false;
     if (!self->setFlag(cx, BaseShape::BOUND_FUNCTION))
         return false;
     if (!JSObject::setSlotSpan(cx, self, BOUND_FUNCTION_RESERVED_SLOTS + argslen))
         return false;
     self->setSlot(JSSLOT_BOUND_FUNCTION_THIS, thisArg);
     self->setSlot(JSSLOT_BOUND_FUNCTION_ARGS_COUNT, PrivateUint32Value(argslen));
     self->initSlotRange(BOUND_FUNCTION_RESERVED_SLOTS, args, argslen);
     return true;
 }
 const js::Value &
 JSFunction::getBoundFunctionThis() const
 {
     JS_ASSERT(isBoundFunction());
     return getSlot(JSSLOT_BOUND_FUNCTION_THIS);
 }
 const js::Value &
 JSFunction::getBoundFunctionArgument(unsigned which) const
 {
     JS_ASSERT(isBoundFunction());
     JS_ASSERT(which < getBoundFunctionArgumentCount());
     return getSlot(BOUND_FUNCTION_RESERVED_SLOTS + which);
 }
 size_t
 JSFunction::getBoundFunctionArgumentCount() const
 {
     JS_ASSERT(isBoundFunction());
     return getSlot(JSSLOT_BOUND_FUNCTION_ARGS_COUNT).toPrivateUint32();
 }
 /* static */ bool
 JSFunction::createScriptForLazilyInterpretedFunction(JSContext *cx, HandleFunction fun)
 {
     JS_ASSERT(fun->isInterpretedLazy());
     Rooted<LazyScript*> lazy(cx, fun->lazyScriptOrNull());
     if (lazy) {
         // Trigger a pre barrier on the lazy script being overwritten.
         if (cx->zone()->needsBarrier())
             LazyScript::writeBarrierPre(lazy);
         // Suppress GC for now although we should be able to remove this by
         // making 'lazy' a Rooted<LazyScript*> (which requires adding a
         // THING_ROOT_LAZY_SCRIPT).
         AutoSuppressGC suppressGC(cx);
         RootedScript script(cx, lazy->maybeScript());
         if (script) {
             fun->setUnlazifiedScript(script);
             // Remember the lazy script on the compiled script, so it can be
             // stored on the function again in case of re-lazification.
             // Only functions without inner functions are re-lazified.
             if (!lazy->numInnerFunctions())
                 script->setLazyScript(lazy);
             return true;
         }
         if (fun != lazy->functionNonDelazifying()) {
             if (!lazy->functionDelazifying(cx))
                 return false;
             script = lazy->functionNonDelazifying()->nonLazyScript();
             if (!script)
                 return false;
             fun->setUnlazifiedScript(script);
             return true;
         }
         // Lazy script caching is only supported for leaf functions. If a
         // script with inner functions was returned by the cache, those inner
         // functions would be delazified when deep cloning the script, even if
         // they have never executed.
         //
         // Additionally, the lazy script cache is not used during incremental
         // GCs, to avoid resurrecting dead scripts after incremental sweeping
         // has started.
         if (!lazy->numInnerFunctions() && !JS::IsIncrementalGCInProgress(cx->runtime())) {
             LazyScriptCache::Lookup lookup(cx, lazy);
             cx->runtime()->lazyScriptCache.lookup(lookup, script.address());
         }
         if (script) {
             RootedObject enclosingScope(cx, lazy->enclosingScope());
             RootedScript clonedScript(cx, CloneScript(cx, enclosingScope, fun, script));
             if (!clonedScript)
                 return false;
             clonedScript->setSourceObject(lazy->sourceObject());
             fun->initAtom(script->functionNonDelazifying()->displayAtom());
             clonedScript->setFunction(fun);
             fun->setUnlazifiedScript(clonedScript);
             CallNewScriptHook(cx, clonedScript, fun);
             if (!lazy->maybeScript())
                 lazy->initScript(clonedScript);
             return true;
         }
         JS_ASSERT(lazy->source()->hasSourceData());
         // Parse and compile the script from source.
         SourceDataCache::AutoHoldEntry holder;
         const jschar *chars = lazy->source()->chars(cx, holder);
         if (!chars)
             return false;
         const jschar *lazyStart = chars + lazy->begin();
         size_t lazyLength = lazy->end() - lazy->begin();
         if (!frontend::CompileLazyFunction(cx, lazy, lazyStart, lazyLength))
             return false;
         script = fun->nonLazyScript();
         // Remember the compiled script on the lazy script itself, in case
         // there are clones of the function still pointing to the lazy script.
         if (!lazy->maybeScript())
             lazy->initScript(script);
         // Try to insert the newly compiled script into the lazy script cache.
         if (!lazy->numInnerFunctions()) {
             // A script's starting column isn't set by the bytecode emitter, so
             // specify this from the lazy script so that if an identical lazy
             // script is encountered later a match can be determined.
             script->setColumn(lazy->column());
             LazyScriptCache::Lookup lookup(cx, lazy);
             cx->runtime()->lazyScriptCache.insert(lookup, script);
             // Remember the lazy script on the compiled script, so it can be
             // stored on the function again in case of re-lazification.
             // Only functions without inner functions are re-lazified.
             script->setLazyScript(lazy);
         }
         return true;
     }
     /* Lazily cloned self-hosted script. */
     JS_ASSERT(fun->isSelfHostedBuiltin());
     RootedAtom funAtom(cx, &fun->getExtendedSlot(0).toString()->asAtom());
     if (!funAtom)
         return false;
     Rooted<PropertyName *> funName(cx, funAtom->asPropertyName());
     return cx->runtime()->cloneSelfHostedFunctionScript(cx, funName, fun);
 }
 void
 JSFunction::relazify(JSTracer *trc)
 {
     JSScript *script = nonLazyScript();
     JS_ASSERT(script->isRelazifiable());
     JS_ASSERT(!compartment()->hasBeenEntered());
     JS_ASSERT(!compartment()->debugMode());
     // If the script's canonical function isn't lazy, we have to mark the
     // script. Otherwise, the following scenario would leave it unmarked
     // and cause it to be swept while a function is still expecting it to be
     // valid:
     // 1. an incremental GC slice causes the canonical function to relazify
     // 2. a clone is used and delazifies the canonical function
     // 3. another GC slice causes the clone to relazify
     // The result is that no function marks the script, but the canonical
     // function expects it to be valid.
     if (script->functionNonDelazifying()->hasScript())
         MarkScriptUnbarriered(trc, &u.i.s.script_, "script");
     flags_ &= ~INTERPRETED;
     flags_ |= INTERPRETED_LAZY;
     LazyScript *lazy = script->maybeLazyScript();
     u.i.s.lazy_ = lazy;
     if (lazy) {
         JS_ASSERT(!isSelfHostedBuiltin());
         // If this is the script stored in the lazy script to be cloned
         // for un-lazifying other functions, reset it so the script can
         // be freed.
         if (lazy->maybeScript() == script)
             lazy->resetScript();
         MarkLazyScriptUnbarriered(trc, &u.i.s.lazy_, "lazyScript");
     } else {
         JS_ASSERT(isSelfHostedBuiltin());
         JS_ASSERT(isExtended());
         JS_ASSERT(getExtendedSlot(0).toString()->isAtom());
     }
 }
 /* ES5 15.3.4.5.1 and 15.3.4.5.2. */
 bool
 js::CallOrConstructBoundFunction(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     RootedFunction fun(cx, &args.callee().as<JSFunction>());
     JS_ASSERT(fun->isBoundFunction());
     /* 15.3.4.5.1 step 1, 15.3.4.5.2 step 3. */
     unsigned argslen = fun->getBoundFunctionArgumentCount();
     if (args.length() + argslen > ARGS_LENGTH_MAX) {
         js_ReportAllocationOverflow(cx);
         return false;
     }
     /* 15.3.4.5.1 step 3, 15.3.4.5.2 step 1. */
     RootedObject target(cx, fun->getBoundFunctionTarget());
     /* 15.3.4.5.1 step 2. */
     const Value &boundThis = fun->getBoundFunctionThis();
     InvokeArgs invokeArgs(cx);
     if (!invokeArgs.init(args.length() + argslen))
         return false;
     /* 15.3.4.5.1, 15.3.4.5.2 step 4. */
     for (unsigned i = 0; i < argslen; i++)
         invokeArgs[i].set(fun->getBoundFunctionArgument(i));
     PodCopy(invokeArgs.array() + argslen, vp + 2, args.length());
     /* 15.3.4.5.1, 15.3.4.5.2 step 5. */
     invokeArgs.setCallee(ObjectValue(*target));
     bool constructing = args.isConstructing();
     if (!constructing)
         invokeArgs.setThis(boundThis);
     if (constructing ? !InvokeConstructor(cx, invokeArgs) : !Invoke(cx, invokeArgs))
         return false;
     args.rval().set(invokeArgs.rval());
     return true;
 }
 static bool
 fun_isGenerator(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     JSFunction *fun;
     if (!IsFunctionObject(args.thisv(), &fun)) {
         args.rval().setBoolean(false);
         return true;
     }
     args.rval().setBoolean(fun->isGenerator());
     return true;
 }
 /* ES5 15.3.4.5. */
 static bool
 fun_bind(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     /* Step 1. */
     Value thisv = args.thisv();
     /* Step 2. */
     if (!js_IsCallable(thisv)) {
         ReportIncompatibleMethod(cx, args, &JSFunction::class_);
         return false;
     }
     /* Step 3. */
     Value *boundArgs = nullptr;
     unsigned argslen = 0;
     if (args.length() > 1) {
         boundArgs = args.array() + 1;
         argslen = args.length() - 1;
     }
     /* Steps 7-9. */
     RootedValue thisArg(cx, args.length() >= 1 ? args[0] : UndefinedValue());
     RootedObject target(cx, &thisv.toObject());
     JSObject *boundFunction = js_fun_bind(cx, target, thisArg, boundArgs, argslen);
     if (!boundFunction)
         return false;
     /* Step 22. */
     args.rval().setObject(*boundFunction);
     return true;
 }
 JSObject*
 js_fun_bind(JSContext *cx, HandleObject target, HandleValue thisArg,
             Value *boundArgs, unsigned argslen)
 {
     /* Steps 15-16. */
     unsigned length = 0;
     if (target->is<JSFunction>()) {
         unsigned nargs = target->as<JSFunction>().nargs();
         if (nargs > argslen)
             length = nargs - argslen;
     }
     /* Step 4-6, 10-11. */
     RootedAtom name(cx, target->is<JSFunction>() ? target->as<JSFunction>().atom() : nullptr);
     RootedObject funobj(cx, NewFunction(cx, js::NullPtr(), CallOrConstructBoundFunction, length,
                                         JSFunction::NATIVE_CTOR, target, name));
     if (!funobj)
         return nullptr;
     /* NB: Bound functions abuse |parent| to store their target. */
     if (!JSObject::setParent(cx, funobj, target))
         return nullptr;
     if (!funobj->as<JSFunction>().initBoundFunction(cx, thisArg, boundArgs, argslen))
         return nullptr;
     /* Steps 17, 19-21 are handled by fun_resolve. */
     /* Step 18 is the default for new functions. */
     return funobj;
 }
 /*
  * Report "malformed formal parameter" iff no illegal char or similar scanner
  * error was already reported.
  */
 static bool
 OnBadFormal(JSContext *cx, TokenKind tt)
 {
     if (tt != TOK_ERROR)
         JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr, JSMSG_BAD_FORMAL);
     else
         JS_ASSERT(cx->isExceptionPending());
     return false;
 }
 const JSFunctionSpec js::function_methods[] = {
 #if JS_HAS_TOSOURCE
     JS_FN(js_toSource_str,   fun_toSource,   0,0),
 #endif
     JS_FN(js_toString_str,   fun_toString,   0,0),
     JS_FN(js_apply_str,      js_fun_apply,   2,0),
     JS_FN(js_call_str,       js_fun_call,    1,0),
     JS_FN("bind",            fun_bind,       1,0),
     JS_FN("isGenerator",     fun_isGenerator,0,0),
     JS_FS_END
 };
 static bool
 FunctionConstructor(JSContext *cx, unsigned argc, Value *vp, GeneratorKind generatorKind)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     RootedString arg(cx);   // used multiple times below
     /* Block this call if security callbacks forbid it. */
     Rooted<GlobalObject*> global(cx, &args.callee().global());
     if (!GlobalObject::isRuntimeCodeGenEnabled(cx, global)) {
         JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr, JSMSG_CSP_BLOCKED_FUNCTION);
         return false;
     }
     AutoKeepAtoms keepAtoms(cx->perThreadData);
     AutoNameVector formals(cx);
     bool hasRest = false;
     bool isStarGenerator = generatorKind == StarGenerator;
     JS_ASSERT(generatorKind != LegacyGenerator);
     RootedScript maybeScript(cx);
     const char *filename;
     unsigned lineno;
     JSPrincipals *originPrincipals;
     uint32_t pcOffset;
     DescribeScriptedCallerForCompilation(cx, &maybeScript, &filename, &lineno, &pcOffset,
                                          &originPrincipals);
     const char *introductionType = "Function";
     if (generatorKind != NotGenerator)
         introductionType = "GeneratorFunction";
     const char *introducerFilename = filename;
     if (maybeScript && maybeScript->scriptSource()->introducerFilename())
         introducerFilename = maybeScript->scriptSource()->introducerFilename();
     CompileOptions options(cx);
     options.setOriginPrincipals(originPrincipals)
            .setFileAndLine(filename, 1)
            .setNoScriptRval(false)
            .setCompileAndGo(true)
            .setIntroductionInfo(introducerFilename, introductionType, lineno, maybeScript, pcOffset);
     unsigned n = args.length() ? args.length() - 1 : 0;
     if (n > 0) {
         /*
          * Collect the function-argument arguments into one string, separated
          * by commas, then make a tokenstream from that string, and scan it to
          * get the arguments.  We need to throw the full scanner at the
          * problem, because the argument string can legitimately contain
          * comments and linefeeds.  XXX It might be better to concatenate
          * everything up into a function definition and pass it to the
          * compiler, but doing it this way is less of a delta from the old
          * code.  See ECMA 15.3.2.1.
          */
         size_t args_length = 0;
         for (unsigned i = 0; i < n; i++) {
             /* Collect the lengths for all the function-argument arguments. */
             arg = ToString<CanGC>(cx, args[i]);
             if (!arg)
                 return false;
             args[i].setString(arg);
             /*
              * Check for overflow.  The < test works because the maximum
              * JSString length fits in 2 fewer bits than size_t has.
              */
             size_t old_args_length = args_length;
             args_length = old_args_length + arg->length();
             if (args_length < old_args_length) {
                 js_ReportAllocationOverflow(cx);
                 return false;
             }
         }
         /* Add 1 for each joining comma and check for overflow (two ways). */
         size_t old_args_length = args_length;
         args_length = old_args_length + n - 1;
         if (args_length < old_args_length ||
             args_length >= ~(size_t)0 / sizeof(jschar)) {
             js_ReportAllocationOverflow(cx);
             return false;
         }
         /*
          * Allocate a string to hold the concatenated arguments, including room
          * for a terminating 0. Mark cx->tempLifeAlloc for later release, to
          * free collected_args and its tokenstream in one swoop.
          */
         LifoAllocScope las(&cx->tempLifoAlloc());
         jschar *cp = cx->tempLifoAlloc().newArray<jschar>(args_length + 1);
         if (!cp) {
             js_ReportOutOfMemory(cx);
             return false;
         }
         ConstTwoByteChars collected_args(cp, args_length + 1);
         /*
          * Concatenate the arguments into the new string, separated by commas.
          */
         for (unsigned i = 0; i < n; i++) {
             arg = args[i].toString();
             size_t arg_length = arg->length();
             const jschar *arg_chars = arg->getChars(cx);
             if (!arg_chars)
                 return false;
             (void) js_strncpy(cp, arg_chars, arg_length);
             cp += arg_length;
             /* Add separating comma or terminating 0. */
             *cp++ = (i + 1 < n) ? ',' : 0;
         }
         /*
          * Initialize a tokenstream that reads from the given string.  No
          * StrictModeGetter is needed because this TokenStream won't report any
          * strict mode errors.  Any strict mode errors which might be reported
          * here (duplicate argument names, etc.) will be detected when we
          * compile the function body.
          */
         TokenStream ts(cx, options, collected_args.get(), args_length,
                        /* strictModeGetter = */ nullptr);
         bool yieldIsValidName = ts.versionNumber() < JSVERSION_1_7 && !isStarGenerator;
         /* The argument string may be empty or contain no tokens. */
         TokenKind tt = ts.getToken();
         if (tt != TOK_EOF) {
             for (;;) {
                 /*
                  * Check that it's a name.  This also implicitly guards against
                  * TOK_ERROR, which was already reported.
                  */
                 if (hasRest) {
                     ts.reportError(JSMSG_PARAMETER_AFTER_REST);
                     return false;
                 }
                 if (tt == TOK_YIELD && yieldIsValidName)
                     tt = TOK_NAME;
                 if (tt != TOK_NAME) {
                     if (tt == TOK_TRIPLEDOT) {
                         hasRest = true;
                         tt = ts.getToken();
                         if (tt == TOK_YIELD && yieldIsValidName)
                             tt = TOK_NAME;
                         if (tt != TOK_NAME) {
                             if (tt != TOK_ERROR)
                                 ts.reportError(JSMSG_NO_REST_NAME);
                             return false;
                         }
                     } else {
                         return OnBadFormal(cx, tt);
                     }
                 }
                 if (!formals.append(ts.currentName()))
                     return false;
                 /*
                  * Get the next token.  Stop on end of stream.  Otherwise
                  * insist on a comma, get another name, and iterate.
                  */
                 tt = ts.getToken();
                 if (tt == TOK_EOF)
                     break;
                 if (tt != TOK_COMMA)
                     return OnBadFormal(cx, tt);
                 tt = ts.getToken();
             }
         }
     }
 #ifdef DEBUG
     for (unsigned i = 0; i < formals.length(); ++i) {
         JSString *str = formals[i];
         JS_ASSERT(str->asAtom().asPropertyName() == formals[i]);
     }
 #endif
     RootedString str(cx);
     if (!args.length())
         str = cx->runtime()->emptyString;
     else
         str = ToString<CanGC>(cx, args[args.length() - 1]);
     if (!str)
         return false;
     JSLinearString *linear = str->ensureLinear(cx);
     if (!linear)
         return false;
     JS::Anchor<JSString *> strAnchor(str);
     const jschar *chars = linear->chars();
     size_t length = linear->length();
     /*
      * NB: (new Function) is not lexically closed by its caller, it's just an
      * anonymous function in the top-level scope that its constructor inhabits.
      * Thus 'var x = 42; f = new Function("return x"); print(f())' prints 42,
      * and so would a call to f from another top-level's script or function.
      */
     RootedAtom anonymousAtom(cx, cx->names().anonymous);
     JSObject *proto = nullptr;
     if (isStarGenerator) {
         proto = GlobalObject::getOrCreateStarGeneratorFunctionPrototype(cx, global);
         if (!proto)
             return false;
     }
     RootedFunction fun(cx, NewFunctionWithProto(cx, js::NullPtr(), nullptr, 0,
                                                 JSFunction::INTERPRETED_LAMBDA, global,
                                                 anonymousAtom, proto,
                                                 JSFunction::FinalizeKind, TenuredObject));
     if (!fun)
         return false;
     if (!JSFunction::setTypeForScriptedFunction(cx, fun))
         return false;
     if (hasRest)
         fun->setHasRest();
     bool ok;
     SourceBufferHolder srcBuf(chars, length, SourceBufferHolder::NoOwnership);
     if (isStarGenerator)
         ok = frontend::CompileStarGeneratorBody(cx, &fun, options, formals, srcBuf);
     else
         ok = frontend::CompileFunctionBody(cx, &fun, options, formals, srcBuf);
     args.rval().setObject(*fun);
     return ok;
 }
 bool
 js::Function(JSContext *cx, unsigned argc, Value *vp)
 {
     return FunctionConstructor(cx, argc, vp, NotGenerator);
 }
 bool
 js::Generator(JSContext *cx, unsigned argc, Value *vp)
 {
     return FunctionConstructor(cx, argc, vp, StarGenerator);
 }
 bool
 JSFunction::isBuiltinFunctionConstructor()
 {
     return maybeNative() == Function || maybeNative() == Generator;
 }
 JSFunction *
 js::NewFunction(ExclusiveContext *cx, HandleObject funobjArg, Native native, unsigned nargs,
                 JSFunction::Flags flags, HandleObject parent, HandleAtom atom,
                 gc::AllocKind allocKind /* = JSFunction::FinalizeKind */,
                 NewObjectKind newKind /* = GenericObject */)
 {
     return NewFunctionWithProto(cx, funobjArg, native, nargs, flags, parent, atom, nullptr,
                                 allocKind, newKind);
 }
 JSFunction *
 js::NewFunctionWithProto(ExclusiveContext *cx, HandleObject funobjArg, Native native,
                          unsigned nargs, JSFunction::Flags flags, HandleObject parent,
                          HandleAtom atom, JSObject *proto,
                          gc::AllocKind allocKind /* = JSFunction::FinalizeKind */,
                          NewObjectKind newKind /* = GenericObject */)
 {
     JS_ASSERT(allocKind == JSFunction::FinalizeKind || allocKind == JSFunction::ExtendedFinalizeKind);
     JS_ASSERT(sizeof(JSFunction) <= gc::Arena::thingSize(JSFunction::FinalizeKind));
     JS_ASSERT(sizeof(FunctionExtended) <= gc::Arena::thingSize(JSFunction::ExtendedFinalizeKind));
     RootedObject funobj(cx, funobjArg);
     if (funobj) {
         JS_ASSERT(funobj->is<JSFunction>());
         JS_ASSERT(funobj->getParent() == parent);
         JS_ASSERT_IF(native, funobj->hasSingletonType());
     } else {
         // Don't give asm.js module functions a singleton type since they
         // are cloned (via CloneFunctionObjectIfNotSingleton) which assumes
         // that hasSingletonType implies isInterpreted.
         if (native && !IsAsmJSModuleNative(native))
             newKind = SingletonObject;
         funobj = NewObjectWithClassProto(cx, &JSFunction::class_, proto,
                                          SkipScopeParent(parent), allocKind, newKind);
         if (!funobj)
             return nullptr;
     }
     RootedFunction fun(cx, &funobj->as<JSFunction>());
     if (allocKind == JSFunction::ExtendedFinalizeKind)
         flags = JSFunction::Flags(flags | JSFunction::EXTENDED);
     /* Initialize all function members. */
     fun->setArgCount(uint16_t(nargs));
     fun->setFlags(flags);
     if (fun->isInterpreted()) {
         JS_ASSERT(!native);
         fun->mutableScript().init(nullptr);
         fun->initEnvironment(parent);
     } else {
         JS_ASSERT(fun->isNative());
         JS_ASSERT(native);
         fun->initNative(native, nullptr);
     }
     if (allocKind == JSFunction::ExtendedFinalizeKind)
         fun->initializeExtended();
     fun->initAtom(atom);
     return fun;
 }
 JSFunction *
 js::CloneFunctionObject(JSContext *cx, HandleFunction fun, HandleObject parent, gc::AllocKind allocKind,
                         NewObjectKind newKindArg /* = GenericObject */)
 {
     JS_ASSERT(parent);
     JS_ASSERT(!fun->isBoundFunction());
     bool useSameScript = cx->compartment() == fun->compartment() &&
                          !fun->hasSingletonType() &&
                          !types::UseNewTypeForClone(fun);
     if (!useSameScript && fun->isInterpretedLazy() && !fun->getOrCreateScript(cx))
         return nullptr;
     NewObjectKind newKind = useSameScript ? newKindArg : SingletonObject;
     JSObject *cloneProto = nullptr;
     if (fun->isStarGenerator()) {
         cloneProto = GlobalObject::getOrCreateStarGeneratorFunctionPrototype(cx, cx->global());
         if (!cloneProto)
             return nullptr;
     }
     JSObject *cloneobj = NewObjectWithClassProto(cx, &JSFunction::class_, cloneProto,
                                                  SkipScopeParent(parent), allocKind, newKind);
     if (!cloneobj)
         return nullptr;
     RootedFunction clone(cx, &cloneobj->as<JSFunction>());
     uint16_t flags = fun->flags() & ~JSFunction::EXTENDED;
     if (allocKind == JSFunction::ExtendedFinalizeKind)
         flags |= JSFunction::EXTENDED;
     clone->setArgCount(fun->nargs());
     clone->setFlags(flags);
     if (fun->hasScript()) {
         clone->initScript(fun->nonLazyScript());
         clone->initEnvironment(parent);
     } else if (fun->isInterpretedLazy()) {
         LazyScript *lazy = fun->lazyScriptOrNull();
         clone->initLazyScript(lazy);
         clone->initEnvironment(parent);
     } else {
         clone->initNative(fun->native(), fun->jitInfo());
     }
     clone->initAtom(fun->displayAtom());
     if (allocKind == JSFunction::ExtendedFinalizeKind) {
         if (fun->isExtended() && fun->compartment() == cx->compartment()) {
             for (unsigned i = 0; i < FunctionExtended::NUM_EXTENDED_SLOTS; i++)
                 clone->initExtendedSlot(i, fun->getExtendedSlot(i));
         } else {
             clone->initializeExtended();
         }
     }
     if (useSameScript) {
         /*
          * Clone the function, reusing its script. We can use the same type as
          * the original function provided that its prototype is correct.
          */
         if (fun->getProto() == clone->getProto())
             clone->setType(fun->type());
         return clone;
     }
     RootedFunction cloneRoot(cx, clone);
     /*
      * Across compartments we have to clone the script for interpreted
      * functions. Cross-compartment cloning only happens via JSAPI
      * (JS_CloneFunctionObject) which dynamically ensures that 'script' has
      * no enclosing lexical scope (only the global scope).
      */
     if (cloneRoot->isInterpreted() && !CloneFunctionScript(cx, fun, cloneRoot, newKindArg))
         return nullptr;
     return cloneRoot;
 }
 JSFunction *
 js::DefineFunction(JSContext *cx, HandleObject obj, HandleId id, Native native,
                    unsigned nargs, unsigned flags, AllocKind allocKind /* = FinalizeKind */,
                    NewObjectKind newKind /* = GenericObject */)
 {
     PropertyOp gop;
     StrictPropertyOp sop;
     RootedFunction fun(cx);
     if (flags & JSFUN_STUB_GSOPS) {
         /*
          * JSFUN_STUB_GSOPS is a request flag only, not stored in fun->flags or
          * the defined property's attributes. This allows us to encode another,
          * internal flag using the same bit, JSFUN_EXPR_CLOSURE -- see jsfun.h
          * for more on this.
          */
         flags &= ~JSFUN_STUB_GSOPS;
         gop = JS_PropertyStub;
         sop = JS_StrictPropertyStub;
     } else {
         gop = nullptr;
         sop = nullptr;
     }
     JSFunction::Flags funFlags;
     if (!native)
         funFlags = JSFunction::INTERPRETED_LAZY;
     else
         funFlags = JSAPIToJSFunctionFlags(flags);
     RootedAtom atom(cx, JSID_IS_ATOM(id) ? JSID_TO_ATOM(id) : nullptr);
     fun = NewFunction(cx, NullPtr(), native, nargs, funFlags, obj, atom, allocKind, newKind);
     if (!fun)
         return nullptr;
     RootedValue funVal(cx, ObjectValue(*fun));
     if (!JSObject::defineGeneric(cx, obj, id, funVal, gop, sop, flags & ~JSFUN_FLAGS_MASK))
         return nullptr;
     return fun;
 }
 bool
 js::IsConstructor(const Value &v)
 {
     // Step 2.
     if (!v.isObject())
         return false;
     // Step 3-4, a bit complex for us, since we have several flavors of
     // [[Construct]] internal method.
     JSObject &obj = v.toObject();
     if (obj.is<JSFunction>()) {
         JSFunction &fun = obj.as<JSFunction>();
         return fun.isNativeConstructor() || fun.isInterpretedConstructor();
     }
     return obj.getClass()->construct != nullptr;
 }
 void
 js::ReportIncompatibleMethod(JSContext *cx, CallReceiver call, const Class *clasp)
 {
     RootedValue thisv(cx, call.thisv());
 #ifdef DEBUG
     if (thisv.isObject()) {
         JS_ASSERT(thisv.toObject().getClass() != clasp ||
                   !thisv.toObject().isNative() ||
                   !thisv.toObject().getProto() ||
                   thisv.toObject().getProto()->getClass() != clasp);
     } else if (thisv.isString()) {
         JS_ASSERT(clasp != &StringObject::class_);
     } else if (thisv.isNumber()) {
         JS_ASSERT(clasp != &NumberObject::class_);
     } else if (thisv.isBoolean()) {
         JS_ASSERT(clasp != &BooleanObject::class_);
     } else {
         JS_ASSERT(thisv.isUndefined() || thisv.isNull());
     }
 #endif
     if (JSFunction *fun = ReportIfNotFunction(cx, call.calleev())) {
         JSAutoByteString funNameBytes;
         if (const char *funName = GetFunctionNameBytes(cx, fun, &funNameBytes)) {
             JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr, JSMSG_INCOMPATIBLE_PROTO,
                                  clasp->name, funName, InformalValueTypeName(thisv));
         }
     }
 }
 void
 js::ReportIncompatible(JSContext *cx, CallReceiver call)
 {
     if (JSFunction *fun = ReportIfNotFunction(cx, call.calleev())) {
         JSAutoByteString funNameBytes;
         if (const char *funName = GetFunctionNameBytes(cx, fun, &funNameBytes)) {
             JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr, JSMSG_INCOMPATIBLE_METHOD,
                                  funName, "method", InformalValueTypeName(call.thisv()));
         }
     }
 }
 bool
 JSObject::hasIdempotentProtoChain() const
 {
     // Return false if obj (or an object on its proto chain) is non-native or
     // has a resolve or lookup hook.
     JSObject *obj = const_cast<JSObject *>(this);
     while (true) {
         if (!obj->isNative())
             return false;
         JSResolveOp resolve = obj->getClass()->resolve;
         if (resolve != JS_ResolveStub && resolve != (JSResolveOp) js::fun_resolve)
             return false;
         if (obj->getOps()->lookupProperty || obj->getOps()->lookupGeneric || obj->getOps()->lookupElement)
             return false;
         obj = obj->getProto();
         if (!obj)
             return true;
     }
     MOZ_ASSUME_UNREACHABLE("Should not get here");
 }
 namespace JS {
 namespace detail {
 JS_PUBLIC_API(void)
 CheckIsValidConstructible(Value calleev)
 {
     JSObject *callee = &calleev.toObject();
     if (callee->is<JSFunction>())
         JS_ASSERT(callee->as<JSFunction>().isNativeConstructor());
     else
         JS_ASSERT(callee->getClass()->construct != nullptr);
 }
 } // namespace detail
 } // namespace JS

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js/src/jsfun.cpp