gecko-dev/devtools/server/actors/object.js

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JavaScript

/* 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/. */
"use strict";
const { Cu } = require("chrome");
const DevToolsUtils = require("devtools/shared/DevToolsUtils");
const { assert } = DevToolsUtils;
const protocol = require("devtools/shared/protocol");
const { objectSpec } = require("devtools/shared/specs/object");
loader.lazyRequireGetter(
this,
"PropertyIteratorActor",
"devtools/server/actors/object/property-iterator",
true
);
loader.lazyRequireGetter(
this,
"SymbolIteratorActor",
"devtools/server/actors/object/symbol-iterator",
true
);
loader.lazyRequireGetter(
this,
"previewers",
"devtools/server/actors/object/previewers"
);
loader.lazyRequireGetter(
this,
"stringify",
"devtools/server/actors/object/stringifiers"
);
const {
getArrayLength,
getPromiseState,
getStorageLength,
isArray,
isStorage,
isTypedArray,
} = require("devtools/server/actors/object/utils");
const proto = {
/**
* Creates an actor for the specified object.
*
* @param obj Debugger.Object
* The debuggee object.
* @param Object
* A collection of abstract methods that are implemented by the caller.
* ObjectActor requires the following functions to be implemented by
* the caller:
* - createValueGrip
* Creates a value grip for the given object
* - sources
* TabSources getter that manages the sources of a thread
* - createEnvironmentActor
* Creates and return an environment actor
* - getGripDepth
* An actor's grip depth getter
* - incrementGripDepth
* Increment the actor's grip depth
* - decrementGripDepth
* Decrement the actor's grip depth
* - globalDebugObject
* The Debuggee Global Object as given by the ThreadActor
*/
initialize(
obj,
{
createValueGrip: createValueGripHook,
sources,
createEnvironmentActor,
getGripDepth,
incrementGripDepth,
decrementGripDepth,
getGlobalDebugObject,
},
conn
) {
assert(
!obj.optimizedOut,
"Should not create object actors for optimized out values!"
);
protocol.Actor.prototype.initialize.call(this, conn);
this.conn = conn;
this.obj = obj;
this.hooks = {
createValueGrip: createValueGripHook,
sources,
createEnvironmentActor,
getGripDepth,
incrementGripDepth,
decrementGripDepth,
getGlobalDebugObject,
};
},
rawValue: function() {
return this.obj.unsafeDereference();
},
/**
* Returns a grip for this actor for returning in a protocol message.
*/
form: function() {
const g = {
type: "object",
actor: this.actorID,
};
// Unsafe objects must be treated carefully.
if (DevToolsUtils.isCPOW(this.obj)) {
// Cross-process object wrappers can't be accessed.
g.class = "CPOW";
return g;
}
const unwrapped = DevToolsUtils.unwrap(this.obj);
if (unwrapped === undefined) {
// Objects belonging to an invisible-to-debugger compartment might be proxies,
// so just in case they shouldn't be accessed.
g.class = "InvisibleToDebugger: " + this.obj.class;
return g;
}
if (unwrapped && unwrapped.isProxy) {
// Proxy objects can run traps when accessed, so just create a preview with
// the target and the handler.
g.class = "Proxy";
this.hooks.incrementGripDepth();
previewers.Proxy[0](this, g, null);
this.hooks.decrementGripDepth();
return g;
}
// If the debuggee does not subsume the object's compartment, most properties won't
// be accessible. Cross-orgin Window and Location objects might expose some, though.
// Change the displayed class, but when creating the preview use the original one.
if (unwrapped === null) {
g.class = "Restricted";
} else {
g.class = this.obj.class;
}
this.hooks.incrementGripDepth();
g.extensible = this.obj.isExtensible();
g.frozen = this.obj.isFrozen();
g.sealed = this.obj.isSealed();
if (g.class == "Promise") {
g.promiseState = this._createPromiseState();
}
// FF40+: Allow to know how many properties an object has to lazily display them
// when there is a bunch.
if (isTypedArray(g)) {
// Bug 1348761: getOwnPropertyNames is unnecessary slow on TypedArrays
g.ownPropertyLength = getArrayLength(this.obj);
} else if (isStorage(g)) {
g.ownPropertyLength = getStorageLength(this.obj);
} else if (isReplaying) {
// When replaying we can get the number of properties directly, to avoid
// needing to enumerate all of them.
g.ownPropertyLength = this.obj.getOwnPropertyNamesCount();
} else {
try {
g.ownPropertyLength = this.obj.getOwnPropertyNames().length;
} catch (err) {
// The above can throw when the debuggee does not subsume the object's
// compartment, or for some WrappedNatives like Cu.Sandbox.
}
}
let raw = this.obj.unsafeDereference();
// If Cu is not defined, we are running on a worker thread, where xrays
// don't exist. The raw object will be null/unavailable when interacting
// with a replaying execution.
if (raw && Cu) {
raw = Cu.unwaiveXrays(raw);
}
if (raw && !DevToolsUtils.isSafeJSObject(raw)) {
raw = null;
}
for (const fn of previewers[this.obj.class] || previewers.Object) {
try {
if (fn(this, g, raw)) {
break;
}
} catch (e) {
const msg = "ObjectActor.prototype.grip previewer function";
DevToolsUtils.reportException(msg, e);
}
}
this.hooks.decrementGripDepth();
return g;
},
/**
* Returns an object exposing the internal Promise state.
*/
_createPromiseState: function() {
const { state, value, reason } = getPromiseState(this.obj);
const promiseState = { state };
if (state == "fulfilled") {
promiseState.value = this.hooks.createValueGrip(value);
} else if (state == "rejected") {
promiseState.reason = this.hooks.createValueGrip(reason);
}
promiseState.creationTimestamp = Date.now() - this.obj.promiseLifetime;
// Only add the timeToSettle property if the Promise isn't pending.
if (state !== "pending") {
promiseState.timeToSettle = this.obj.promiseTimeToResolution;
}
return promiseState;
},
/**
* Handle a protocol request to provide the definition site of this function
* object.
*/
definitionSite: function() {
if (this.obj.class != "Function") {
return this.throwError(
"objectNotFunction",
this.actorID + " is not a function."
);
}
if (!this.obj.script) {
return this.throwError(
"noScript",
this.actorID + " has no Debugger.Script"
);
}
return {
source: this.hooks.sources().createSourceActor(this.obj.script.source),
line: this.obj.script.startLine,
column: 0, // TODO bug 901138: use Debugger.Script.prototype.startColumn
};
},
/**
* Handle a protocol request to provide the names of the properties defined on
* the object and not its prototype.
*/
ownPropertyNames: function() {
let props = [];
if (DevToolsUtils.isSafeDebuggerObject(this.obj)) {
try {
props = this.obj.getOwnPropertyNames();
} catch (err) {
// The above can throw when the debuggee does not subsume the object's
// compartment, or for some WrappedNatives like Cu.Sandbox.
}
}
return { ownPropertyNames: props };
},
/**
* Creates an actor to iterate over an object property names and values.
* See PropertyIteratorActor constructor for more info about options param.
*
* @param options object
*/
enumProperties: function(options) {
return PropertyIteratorActor(this, options, this.conn);
},
/**
* Creates an actor to iterate over entries of a Map/Set-like object.
*/
enumEntries: function() {
return PropertyIteratorActor(this, { enumEntries: true }, this.conn);
},
/**
* Creates an actor to iterate over an object symbols properties.
*/
enumSymbols: function() {
return SymbolIteratorActor(this, this.conn);
},
/**
* Handle a protocol request to provide the prototype and own properties of
* the object.
*
* @returns {Object} An object containing the data of this.obj, of the following form:
* - {Object} prototype: The descriptor of this.obj's prototype.
* - {Object} ownProperties: an object where the keys are the names of the
* this.obj's ownProperties, and the values the descriptors of
* the properties.
* - {Array} ownSymbols: An array containing all descriptors of this.obj's
* ownSymbols. Here we have an array, and not an object like for
* ownProperties, because we can have multiple symbols with the same
* name in this.obj, e.g. `{[Symbol()]: "a", [Symbol()]: "b"}`.
* - {Object} safeGetterValues: an object that maps this.obj's property names
* with safe getters descriptors.
*/
prototypeAndProperties: function() {
let objProto = null;
let names = [];
let symbols = [];
if (DevToolsUtils.isSafeDebuggerObject(this.obj)) {
try {
objProto = this.obj.proto;
names = this.obj.getOwnPropertyNames();
symbols = this.obj.getOwnPropertySymbols();
} catch (err) {
// The above can throw when the debuggee does not subsume the object's
// compartment, or for some WrappedNatives like Cu.Sandbox.
}
}
const ownProperties = Object.create(null);
const ownSymbols = [];
for (const name of names) {
ownProperties[name] = this._propertyDescriptor(name);
}
for (const sym of symbols) {
ownSymbols.push({
name: sym.toString(),
descriptor: this._propertyDescriptor(sym),
});
}
return {
prototype: this.hooks.createValueGrip(objProto),
ownProperties,
ownSymbols,
safeGetterValues: this._findSafeGetterValues(names),
};
},
/**
* Find the safe getter values for the current Debugger.Object, |this.obj|.
*
* @private
* @param array ownProperties
* The array that holds the list of known ownProperties names for
* |this.obj|.
* @param number [limit=0]
* Optional limit of getter values to find.
* @return object
* An object that maps property names to safe getter descriptors as
* defined by the remote debugging protocol.
*/
/* eslint-disable complexity */
_findSafeGetterValues: function(ownProperties, limit = 0) {
const safeGetterValues = Object.create(null);
let obj = this.obj;
let level = 0,
i = 0;
// Do not search safe getters in unsafe objects.
if (!DevToolsUtils.isSafeDebuggerObject(obj)) {
return safeGetterValues;
}
// Do not search for safe getters while replaying. While this would be nice
// to support, it involves a lot of back-and-forth between processes and
// would be better to do entirely in the replaying process.
if (isReplaying) {
return safeGetterValues;
}
// Most objects don't have any safe getters but inherit some from their
// prototype. Avoid calling getOwnPropertyNames on objects that may have
// many properties like Array, strings or js objects. That to avoid
// freezing firefox when doing so.
if (isArray(this.obj) || ["Object", "String"].includes(this.obj.class)) {
obj = obj.proto;
level++;
}
while (obj && DevToolsUtils.isSafeDebuggerObject(obj)) {
const getters = this._findSafeGetters(obj);
for (const name of getters) {
// Avoid overwriting properties from prototypes closer to this.obj. Also
// avoid providing safeGetterValues from prototypes if property |name|
// is already defined as an own property.
if (
name in safeGetterValues ||
(obj != this.obj && ownProperties.includes(name))
) {
continue;
}
// Ignore __proto__ on Object.prototye.
if (!obj.proto && name == "__proto__") {
continue;
}
let desc = null,
getter = null;
try {
desc = obj.getOwnPropertyDescriptor(name);
getter = desc.get;
} catch (ex) {
// The above can throw if the cache becomes stale.
}
if (!getter) {
obj._safeGetters = null;
continue;
}
const result = getter.call(this.obj);
if (!result || "throw" in result) {
continue;
}
let getterValue = undefined;
if ("return" in result) {
getterValue = result.return;
} else if ("yield" in result) {
getterValue = result.yield;
}
// Treat an already-rejected Promise as we would a thrown exception
// by not including it as a safe getter value (see Bug 1477765).
if (
getterValue &&
(getterValue.class == "Promise" &&
getterValue.promiseState == "rejected")
) {
// Until we have a good way to handle Promise rejections through the
// debugger API (Bug 1478076), call `catch` when it's safe to do so.
const raw = getterValue.unsafeDereference();
if (DevToolsUtils.isSafeJSObject(raw)) {
raw.catch(e => e);
}
continue;
}
// WebIDL attributes specified with the LenientThis extended attribute
// return undefined and should be ignored.
if (getterValue !== undefined) {
safeGetterValues[name] = {
getterValue: this.hooks.createValueGrip(getterValue),
getterPrototypeLevel: level,
enumerable: desc.enumerable,
writable: level == 0 ? desc.writable : true,
};
if (limit && ++i == limit) {
break;
}
}
}
if (limit && i == limit) {
break;
}
obj = obj.proto;
level++;
}
return safeGetterValues;
},
/* eslint-enable complexity */
/**
* Find the safe getters for a given Debugger.Object. Safe getters are native
* getters which are safe to execute.
*
* @private
* @param Debugger.Object object
* The Debugger.Object where you want to find safe getters.
* @return Set
* A Set of names of safe getters. This result is cached for each
* Debugger.Object.
*/
_findSafeGetters: function(object) {
if (object._safeGetters) {
return object._safeGetters;
}
const getters = new Set();
if (!DevToolsUtils.isSafeDebuggerObject(object)) {
object._safeGetters = getters;
return getters;
}
let names = [];
try {
names = object.getOwnPropertyNames();
} catch (ex) {
// Calling getOwnPropertyNames() on some wrapped native prototypes is not
// allowed: "cannot modify properties of a WrappedNative". See bug 952093.
}
for (const name of names) {
let desc = null;
try {
desc = object.getOwnPropertyDescriptor(name);
} catch (e) {
// Calling getOwnPropertyDescriptor on wrapped native prototypes is not
// allowed (bug 560072).
}
if (!desc || desc.value !== undefined || !("get" in desc)) {
continue;
}
if (DevToolsUtils.hasSafeGetter(desc)) {
getters.add(name);
}
}
object._safeGetters = getters;
return getters;
},
/**
* Handle a protocol request to provide the prototype of the object.
*/
prototype: function() {
let objProto = null;
if (DevToolsUtils.isSafeDebuggerObject(this.obj)) {
objProto = this.obj.proto;
}
return { prototype: this.hooks.createValueGrip(objProto) };
},
/**
* Handle a protocol request to provide the property descriptor of the
* object's specified property.
*
* @param name string
* The property we want the description of.
*/
property: function(name) {
if (!name) {
return this.throwError(
"missingParameter",
"no property name was specified"
);
}
return { descriptor: this._propertyDescriptor(name) };
},
/**
* Handle a protocol request to provide the value of the object's
* specified property.
*
* Note: Since this will evaluate getters, it can trigger execution of
* content code and may cause side effects. This endpoint should only be used
* when you are confident that the side-effects will be safe, or the user
* is expecting the effects.
*
* @param {string} name
* The property we want the value of.
* @param {string|null} receiverId
* The actorId of the receiver to be used if the property is a getter.
* If null or invalid, the receiver will be the referent.
*/
propertyValue: function(name, receiverId) {
if (!name) {
return this.throwError(
"missingParameter",
"no property name was specified"
);
}
let receiver;
if (receiverId) {
const receiverActor = this.conn.getActor(receiverId);
if (receiverActor) {
receiver = receiverActor.obj;
}
}
const value = receiver
? this.obj.getProperty(name, receiver)
: this.obj.getProperty(name);
return { value: this._buildCompletion(value) };
},
/**
* Handle a protocol request to evaluate a function and provide the value of
* the result.
*
* Note: Since this will evaluate the function, it can trigger execution of
* content code and may cause side effects. This endpoint should only be used
* when you are confident that the side-effects will be safe, or the user
* is expecting the effects.
*
* @param {any} context
* The 'this' value to call the function with.
* @param {Array<any>} args
* The array of un-decoded actor objects, or primitives.
*/
apply: function(context, args) {
if (!this.obj.callable) {
return this.throwError("notCallable", "debugee object is not callable");
}
const debugeeContext = this._getValueFromGrip(context);
const debugeeArgs = args && args.map(this._getValueFromGrip, this);
const value = this.obj.apply(debugeeContext, debugeeArgs);
return { value: this._buildCompletion(value) };
},
_getValueFromGrip(grip) {
if (typeof grip !== "object" || !grip) {
return grip;
}
if (typeof grip.actor !== "string") {
return this.throwError(
"invalidGrip",
"grip argument did not include actor ID"
);
}
const actor = this.conn.getActor(grip.actor);
if (!actor) {
return this.throwError(
"unknownActor",
"grip actor did not match a known object"
);
}
return actor.obj;
},
/**
* Converts a Debugger API completion value record into an eqivalent
* object grip for use by the API.
*
* See https://developer.mozilla.org/en-US/docs/Tools/Debugger-API/Conventions#completion-values
* for more specifics on the expected behavior.
*/
_buildCompletion(value) {
let completionGrip = null;
// .apply result will be falsy if the script being executed is terminated
// via the "slow script" dialog.
if (value) {
completionGrip = {};
if ("return" in value) {
completionGrip.return = this.hooks.createValueGrip(value.return);
}
if ("throw" in value) {
completionGrip.throw = this.hooks.createValueGrip(value.throw);
}
}
return completionGrip;
},
/**
* Handle a protocol request to provide the display string for the object.
*/
displayString: function() {
const string = stringify(this.obj);
return { displayString: this.hooks.createValueGrip(string) };
},
/**
* A helper method that creates a property descriptor for the provided object,
* properly formatted for sending in a protocol response.
*
* @private
* @param string name
* The property that the descriptor is generated for.
* @param boolean [onlyEnumerable]
* Optional: true if you want a descriptor only for an enumerable
* property, false otherwise.
* @return object|undefined
* The property descriptor, or undefined if this is not an enumerable
* property and onlyEnumerable=true.
*/
_propertyDescriptor: function(name, onlyEnumerable) {
if (!DevToolsUtils.isSafeDebuggerObject(this.obj)) {
return undefined;
}
let desc;
try {
desc = this.obj.getOwnPropertyDescriptor(name);
} catch (e) {
// Calling getOwnPropertyDescriptor on wrapped native prototypes is not
// allowed (bug 560072). Inform the user with a bogus, but hopefully
// explanatory, descriptor.
return {
configurable: false,
writable: false,
enumerable: false,
value: e.name,
};
}
if (isStorage(this.obj)) {
if (name === "length") {
return undefined;
}
return desc;
}
if (!desc || (onlyEnumerable && !desc.enumerable)) {
return undefined;
}
const retval = {
configurable: desc.configurable,
enumerable: desc.enumerable,
};
if ("value" in desc) {
retval.writable = desc.writable;
retval.value = this.hooks.createValueGrip(desc.value);
} else {
if ("get" in desc) {
retval.get = this.hooks.createValueGrip(desc.get);
}
if ("set" in desc) {
retval.set = this.hooks.createValueGrip(desc.set);
}
}
return retval;
},
/**
* Handle a protocol request to provide the source code of a function.
*
* @param pretty boolean
*/
decompile: function(pretty) {
if (this.obj.class !== "Function") {
return this.throwError(
"objectNotFunction",
"decompile request is only valid for grips with a 'Function' class."
);
}
return { decompiledCode: this.obj.decompile(!!pretty) };
},
/**
* Handle a protocol request to provide the parameters of a function.
*/
parameterNames: function() {
if (this.obj.class !== "Function") {
return this.throwError(
"objectNotFunction",
"'parameterNames' request is only valid for grips with a 'Function' class."
);
}
return { parameterNames: this.obj.parameterNames };
},
/**
* Handle a protocol request to provide the lexical scope of a function.
*/
scope: function() {
if (this.obj.class !== "Function") {
return this.throwError(
"objectNotFunction",
"scope request is only valid for grips with a 'Function' class."
);
}
const { createEnvironmentActor } = this.hooks;
const envActor = createEnvironmentActor(
this.obj.environment,
this.registeredPool
);
if (!envActor) {
return this.throwError(
"notDebuggee",
"cannot access the environment of this function."
);
}
return {
scope: envActor,
};
},
/**
* Handle a protocol request to get the list of dependent promises of a
* promise.
*
* @return object
* Returns an object containing an array of object grips of the
* dependent promises
*/
dependentPromises: function() {
if (this.obj.class != "Promise") {
return this.throwError(
"objectNotPromise",
"'dependentPromises' request is only valid for grips with a 'Promise' class."
);
}
const promises = this.obj.promiseDependentPromises.map(p =>
this.hooks.createValueGrip(p)
);
return { promises };
},
/**
* Handle a protocol request to get the allocation stack of a promise.
*/
allocationStack: function() {
if (this.obj.class != "Promise") {
return this.throwError(
"objectNotPromise",
"'allocationStack' request is only valid for grips with a 'Promise' class."
);
}
let stack = this.obj.promiseAllocationSite;
const allocationStacks = [];
while (stack) {
if (stack.source) {
const source = this._getSourceOriginalLocation(stack);
if (source) {
allocationStacks.push(source);
}
}
stack = stack.parent;
}
return Promise.all(allocationStacks);
},
/**
* Handle a protocol request to get the fulfillment stack of a promise.
*/
fulfillmentStack: function() {
if (this.obj.class != "Promise") {
return this.throwError(
"objectNotPromise",
"'fulfillmentStack' request is only valid for grips with a 'Promise' class."
);
}
let stack = this.obj.promiseResolutionSite;
const fulfillmentStacks = [];
while (stack) {
if (stack.source) {
const source = this._getSourceOriginalLocation(stack);
if (source) {
fulfillmentStacks.push(source);
}
}
stack = stack.parent;
}
return Promise.all(fulfillmentStacks);
},
/**
* Handle a protocol request to get the rejection stack of a promise.
*/
rejectionStack: function() {
if (this.obj.class != "Promise") {
return this.throwError(
"objectNotPromise",
"'rejectionStack' request is only valid for grips with a 'Promise' class."
);
}
let stack = this.obj.promiseResolutionSite;
const rejectionStacks = [];
while (stack) {
if (stack.source) {
const source = this._getSourceOriginalLocation(stack);
if (source) {
rejectionStacks.push(source);
}
}
stack = stack.parent;
}
return Promise.all(rejectionStacks);
},
/**
* Helper function for fetching the source location of a SavedFrame stack.
*
* @param SavedFrame stack
* The promise allocation stack frame
* @return object
* Returns an object containing the source location of the SavedFrame
* stack.
*/
_getSourceOriginalLocation: function(stack) {
let source;
// Catch any errors if the source actor cannot be found
try {
source = this.hooks.sources().getSourceActorsByURL(stack.source)[0];
} catch (e) {
// ignored
}
if (!source) {
return null;
}
return {
source,
line: stack.line,
column: stack.column,
functionDisplayName: stack.functionDisplayName,
};
},
/**
* Handle a protocol request to get the target and handler internal slots of a proxy.
*/
proxySlots: function() {
// There could be transparent security wrappers, unwrap to check if it's a proxy.
// However, retrieve proxyTarget and proxyHandler from `this.obj` to avoid exposing
// the unwrapped target and handler.
const unwrapped = DevToolsUtils.unwrap(this.obj);
if (!unwrapped || !unwrapped.isProxy) {
return this.throwError(
"objectNotProxy",
"'proxySlots' request is only valid for grips with a 'Proxy' class."
);
}
return {
proxyTarget: this.hooks.createValueGrip(this.obj.proxyTarget),
proxyHandler: this.hooks.createValueGrip(this.obj.proxyHandler),
};
},
/**
* Release the actor, when it isn't needed anymore.
* Protocol.js uses this release method to call the destroy method.
*/
release: function() {},
};
exports.ObjectActor = protocol.ActorClassWithSpec(objectSpec, proto);
exports.ObjectActorProto = proto;