puppeteer/src/helper.ts

/**
 * Copyright 2017 Google Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import { TimeoutError } from './Errors';
import * as debug from 'debug';
import * as fs from 'fs';
import { CDPSession } from './Connection';
import { promisify } from 'util';
import Protocol from './protocol';

const openAsync = promisify(fs.open);
const writeAsync = promisify(fs.write);
const closeAsync = promisify(fs.close);

export const debugError = debug('puppeteer:error');

export function assert(value: unknown, message?: string): void {
  if (!value) throw new Error(message);
}

interface AnyClass {
  prototype: object;
}

function getExceptionMessage(
  exceptionDetails: Protocol.Runtime.ExceptionDetails
): string {
  if (exceptionDetails.exception)
    return (
      exceptionDetails.exception.description || exceptionDetails.exception.value
    );
  let message = exceptionDetails.text;
  if (exceptionDetails.stackTrace) {
    for (const callframe of exceptionDetails.stackTrace.callFrames) {
      const location =
        callframe.url +
        ':' +
        callframe.lineNumber +
        ':' +
        callframe.columnNumber;
      const functionName = callframe.functionName || '<anonymous>';
      message += `\n    at ${functionName} (${location})`;
    }
  }
  return message;
}

function valueFromRemoteObject(
  remoteObject: Protocol.Runtime.RemoteObject
): any {
  assert(!remoteObject.objectId, 'Cannot extract value when objectId is given');
  if (remoteObject.unserializableValue) {
    if (remoteObject.type === 'bigint' && typeof BigInt !== 'undefined')
      return BigInt(remoteObject.unserializableValue.replace('n', ''));
    switch (remoteObject.unserializableValue) {
      case '-0':
        return -0;
      case 'NaN':
        return NaN;
      case 'Infinity':
        return Infinity;
      case '-Infinity':
        return -Infinity;
      default:
        throw new Error(
          'Unsupported unserializable value: ' +
            remoteObject.unserializableValue
        );
    }
  }
  return remoteObject.value;
}

async function releaseObject(
  client: CDPSession,
  remoteObject: Protocol.Runtime.RemoteObject
): Promise<void> {
  if (!remoteObject.objectId) return;
  await client
    .send('Runtime.releaseObject', { objectId: remoteObject.objectId })
    .catch((error) => {
      // Exceptions might happen in case of a page been navigated or closed.
      // Swallow these since they are harmless and we don't leak anything in this case.
      debugError(error);
    });
}

function installAsyncStackHooks(classType: AnyClass): void {
  for (const methodName of Reflect.ownKeys(classType.prototype)) {
    const method = Reflect.get(classType.prototype, methodName);
    if (
      methodName === 'constructor' ||
      typeof methodName !== 'string' ||
      methodName.startsWith('_') ||
      typeof method !== 'function' ||
      method.constructor.name !== 'AsyncFunction'
    )
      continue;
    Reflect.set(classType.prototype, methodName, function (...args) {
      const syncStack = {
        stack: '',
      };
      Error.captureStackTrace(syncStack);
      return method.call(this, ...args).catch((error) => {
        const stack = syncStack.stack.substring(
          syncStack.stack.indexOf('\n') + 1
        );
        const clientStack = stack.substring(stack.indexOf('\n'));
        if (
          error instanceof Error &&
          error.stack &&
          !error.stack.includes(clientStack)
        )
          error.stack += '\n  -- ASYNC --\n' + stack;
        throw error;
      });
    });
  }
}

export interface PuppeteerEventListener {
  emitter: NodeJS.EventEmitter;
  eventName: string | symbol;
  handler: (...args: any[]) => void;
}

function addEventListener(
  emitter: NodeJS.EventEmitter,
  eventName: string | symbol,
  handler: (...args: any[]) => void
): PuppeteerEventListener {
  emitter.on(eventName, handler);
  return { emitter, eventName, handler };
}

function removeEventListeners(
  listeners: Array<{
    emitter: NodeJS.EventEmitter;
    eventName: string | symbol;
    handler: (...args: any[]) => void;
  }>
): void {
  for (const listener of listeners)
    listener.emitter.removeListener(listener.eventName, listener.handler);
  listeners.length = 0;
}

function isString(obj: unknown): obj is string {
  return typeof obj === 'string' || obj instanceof String;
}

function isNumber(obj: unknown): obj is number {
  return typeof obj === 'number' || obj instanceof Number;
}

async function waitForEvent<T extends any>(
  emitter: NodeJS.EventEmitter,
  eventName: string | symbol,
  predicate: (event: T) => boolean,
  timeout: number,
  abortPromise: Promise<Error>
): Promise<T> {
  let eventTimeout, resolveCallback, rejectCallback;
  const promise = new Promise<T>((resolve, reject) => {
    resolveCallback = resolve;
    rejectCallback = reject;
  });
  const listener = addEventListener(emitter, eventName, (event) => {
    if (!predicate(event)) return;
    resolveCallback(event);
  });
  if (timeout) {
    eventTimeout = setTimeout(() => {
      rejectCallback(
        new TimeoutError('Timeout exceeded while waiting for event')
      );
    }, timeout);
  }
  function cleanup(): void {
    removeEventListeners([listener]);
    clearTimeout(eventTimeout);
  }
  const result = await Promise.race([promise, abortPromise]).then(
    (r) => {
      cleanup();
      return r;
    },
    (error) => {
      cleanup();
      throw error;
    }
  );
  if (result instanceof Error) throw result;

  return result;
}

function evaluationString(fun: Function | string, ...args: unknown[]): string {
  if (isString(fun)) {
    assert(args.length === 0, 'Cannot evaluate a string with arguments');
    return fun;
  }

  function serializeArgument(arg: unknown): string {
    if (Object.is(arg, undefined)) return 'undefined';
    return JSON.stringify(arg);
  }

  return `(${fun})(${args.map(serializeArgument).join(',')})`;
}

async function waitWithTimeout<T extends any>(
  promise: Promise<T>,
  taskName: string,
  timeout: number
): Promise<T> {
  let reject;
  const timeoutError = new TimeoutError(
    `waiting for ${taskName} failed: timeout ${timeout}ms exceeded`
  );
  const timeoutPromise = new Promise<T>((resolve, x) => (reject = x));
  let timeoutTimer = null;
  if (timeout) timeoutTimer = setTimeout(() => reject(timeoutError), timeout);
  try {
    return await Promise.race([promise, timeoutPromise]);
  } finally {
    if (timeoutTimer) clearTimeout(timeoutTimer);
  }
}

async function readProtocolStream(
  client: CDPSession,
  handle: string,
  path?: string
): Promise<Buffer> {
  let eof = false;
  let file;
  if (path) file = await openAsync(path, 'w');
  const bufs = [];
  while (!eof) {
    const response = await client.send('IO.read', { handle });
    eof = response.eof;
    const buf = Buffer.from(
      response.data,
      response.base64Encoded ? 'base64' : undefined
    );
    bufs.push(buf);
    if (path) await writeAsync(file, buf);
  }
  if (path) await closeAsync(file);
  await client.send('IO.close', { handle });
  let resultBuffer = null;
  try {
    resultBuffer = Buffer.concat(bufs);
  } finally {
    return resultBuffer;
  }
}

export const helper = {
  promisify,
  evaluationString,
  readProtocolStream,
  waitWithTimeout,
  waitForEvent,
  isString,
  isNumber,
  addEventListener,
  removeEventListeners,
  valueFromRemoteObject,
  installAsyncStackHooks,
  getExceptionMessage,
  releaseObject,
};