pdf.js/src/core/worker.js

/* Copyright 2012 Mozilla Foundation
 *
 * 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 {
  AbortException,
  arrayByteLength,
  arraysToBytes,
  createPromiseCapability,
  getVerbosityLevel,
  info,
  InvalidPDFException,
  isString,
  MissingPDFException,
  PasswordException,
  setVerbosityLevel,
  stringToPDFString,
  UnexpectedResponseException,
  UnknownErrorException,
  UNSUPPORTED_FEATURES,
  VerbosityLevel,
  warn,
} from "../shared/util.js";
import { clearPrimitiveCaches, Dict, Ref } from "./primitives.js";
import { LocalPdfManager, NetworkPdfManager } from "./pdf_manager.js";
import { incrementalUpdate } from "./writer.js";
import { isNodeJS } from "../shared/is_node.js";
import { MessageHandler } from "../shared/message_handler.js";
import { PDFWorkerStream } from "./worker_stream.js";
import { XRefParseException } from "./core_utils.js";

class WorkerTask {
  constructor(name) {
    this.name = name;
    this.terminated = false;
    this._capability = createPromiseCapability();
  }

  get finished() {
    return this._capability.promise;
  }

  finish() {
    this._capability.resolve();
  }

  terminate() {
    this.terminated = true;
  }

  ensureNotTerminated() {
    if (this.terminated) {
      throw new Error("Worker task was terminated");
    }
  }
}

class WorkerMessageHandler {
  static setup(handler, port) {
    let testMessageProcessed = false;
    handler.on("test", function wphSetupTest(data) {
      if (testMessageProcessed) {
        return; // we already processed 'test' message once
      }
      testMessageProcessed = true;

      // check if Uint8Array can be sent to worker
      if (!(data instanceof Uint8Array)) {
        handler.send("test", null);
        return;
      }
      // making sure postMessage transfers are working
      const supportTransfers = data[0] === 255;
      handler.postMessageTransfers = supportTransfers;

      handler.send("test", { supportTransfers });
    });

    handler.on("configure", function wphConfigure(data) {
      setVerbosityLevel(data.verbosity);
    });

    handler.on("GetDocRequest", function wphSetupDoc(data) {
      return WorkerMessageHandler.createDocumentHandler(data, port);
    });
  }

  static createDocumentHandler(docParams, port) {
    // This context is actually holds references on pdfManager and handler,
    // until the latter is destroyed.
    let pdfManager;
    let terminated = false;
    let cancelXHRs = null;
    const WorkerTasks = [];
    const verbosity = getVerbosityLevel();

    const apiVersion = docParams.apiVersion;
    const workerVersion =
      typeof PDFJSDev !== "undefined" && !PDFJSDev.test("TESTING")
        ? PDFJSDev.eval("BUNDLE_VERSION")
        : null;
    if (apiVersion !== workerVersion) {
      throw new Error(
        `The API version "${apiVersion}" does not match ` +
          `the Worker version "${workerVersion}".`
      );
    }

    if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
      // Fail early, and predictably, rather than having (some) fonts fail to
      // load/render with slightly cryptic error messages in environments where
      // the `Array.prototype` has been *incorrectly* extended.
      //
      // PLEASE NOTE: We do *not* want to slow down font parsing by adding
      //              `hasOwnProperty` checks all over the code-base.
      const enumerableProperties = [];
      for (const property in []) {
        enumerableProperties.push(property);
      }
      if (enumerableProperties.length) {
        throw new Error(
          "The `Array.prototype` contains unexpected enumerable properties: " +
            enumerableProperties.join(", ") +
            "; thus breaking e.g. `for...in` iteration of `Array`s."
        );
      }

      // Ensure that (primarily) Node.js users won't accidentally attempt to use
      // a non-translated/non-polyfilled build of the library, since that would
      // quickly fail anyway because of missing functionality.
      if (
        (typeof PDFJSDev === "undefined" || PDFJSDev.test("SKIP_BABEL")) &&
        typeof ReadableStream === "undefined"
      ) {
        throw new Error(
          "The browser/environment lacks native support for critical " +
            "functionality used by the PDF.js library (e.g. `ReadableStream`); " +
            "please use a `legacy`-build instead."
        );
      }
    }

    const docId = docParams.docId;
    const docBaseUrl = docParams.docBaseUrl;
    const workerHandlerName = docParams.docId + "_worker";
    let handler = new MessageHandler(workerHandlerName, docId, port);

    // Ensure that postMessage transfers are always correctly enabled/disabled,
    // to prevent "DataCloneError" in browsers without transfers support.
    handler.postMessageTransfers = docParams.postMessageTransfers;

    function ensureNotTerminated() {
      if (terminated) {
        throw new Error("Worker was terminated");
      }
    }

    function startWorkerTask(task) {
      WorkerTasks.push(task);
    }

    function finishWorkerTask(task) {
      task.finish();
      const i = WorkerTasks.indexOf(task);
      WorkerTasks.splice(i, 1);
    }

    async function loadDocument(recoveryMode) {
      await pdfManager.ensureDoc("checkHeader");
      await pdfManager.ensureDoc("parseStartXRef");
      await pdfManager.ensureDoc("parse", [recoveryMode]);

      if (!recoveryMode) {
        // Check that at least the first page can be successfully loaded,
        // since otherwise the XRef table is definitely not valid.
        await pdfManager.ensureDoc("checkFirstPage");
      }

      const isPureXfa = await pdfManager.ensureDoc("isPureXfa");
      if (isPureXfa) {
        const task = new WorkerTask("loadXfaFonts");
        startWorkerTask(task);
        await Promise.all([
          pdfManager
            .loadXfaFonts(handler, task)
            .catch(reason => {
              // Ignore errors, to allow the document to load.
            })
            .then(() => finishWorkerTask(task)),
          pdfManager.loadXfaImages(),
        ]);
      }

      const [numPages, fingerprints] = await Promise.all([
        pdfManager.ensureDoc("numPages"),
        pdfManager.ensureDoc("fingerprints"),
      ]);

      // Get htmlForXfa after numPages to avoid to create HTML twice.
      const htmlForXfa = isPureXfa
        ? await pdfManager.ensureDoc("htmlForXfa")
        : null;

      return { numPages, fingerprints, htmlForXfa };
    }

    function getPdfManager(data, evaluatorOptions, enableXfa) {
      const pdfManagerCapability = createPromiseCapability();
      let newPdfManager;

      const source = data.source;
      if (source.data) {
        try {
          newPdfManager = new LocalPdfManager(
            docId,
            source.data,
            source.password,
            evaluatorOptions,
            enableXfa,
            docBaseUrl
          );
          pdfManagerCapability.resolve(newPdfManager);
        } catch (ex) {
          pdfManagerCapability.reject(ex);
        }
        return pdfManagerCapability.promise;
      }

      let pdfStream,
        cachedChunks = [];
      try {
        pdfStream = new PDFWorkerStream(handler);
      } catch (ex) {
        pdfManagerCapability.reject(ex);
        return pdfManagerCapability.promise;
      }

      const fullRequest = pdfStream.getFullReader();
      fullRequest.headersReady
        .then(function () {
          if (!fullRequest.isRangeSupported) {
            return;
          }

          // We don't need auto-fetch when streaming is enabled.
          const disableAutoFetch =
            source.disableAutoFetch || fullRequest.isStreamingSupported;
          newPdfManager = new NetworkPdfManager(
            docId,
            pdfStream,
            {
              msgHandler: handler,
              password: source.password,
              length: fullRequest.contentLength,
              disableAutoFetch,
              rangeChunkSize: source.rangeChunkSize,
            },
            evaluatorOptions,
            enableXfa,
            docBaseUrl
          );
          // There may be a chance that `newPdfManager` is not initialized for
          // the first few runs of `readchunk` block of code. Be sure to send
          // all cached chunks, if any, to chunked_stream via pdf_manager.
          for (let i = 0; i < cachedChunks.length; i++) {
            newPdfManager.sendProgressiveData(cachedChunks[i]);
          }

          cachedChunks = [];
          pdfManagerCapability.resolve(newPdfManager);
          cancelXHRs = null;
        })
        .catch(function (reason) {
          pdfManagerCapability.reject(reason);
          cancelXHRs = null;
        });

      let loaded = 0;
      const flushChunks = function () {
        const pdfFile = arraysToBytes(cachedChunks);
        if (source.length && pdfFile.length !== source.length) {
          warn("reported HTTP length is different from actual");
        }
        // the data is array, instantiating directly from it
        try {
          newPdfManager = new LocalPdfManager(
            docId,
            pdfFile,
            source.password,
            evaluatorOptions,
            enableXfa,
            docBaseUrl
          );
          pdfManagerCapability.resolve(newPdfManager);
        } catch (ex) {
          pdfManagerCapability.reject(ex);
        }
        cachedChunks = [];
      };
      const readPromise = new Promise(function (resolve, reject) {
        const readChunk = function ({ value, done }) {
          try {
            ensureNotTerminated();
            if (done) {
              if (!newPdfManager) {
                flushChunks();
              }
              cancelXHRs = null;
              return;
            }

            loaded += arrayByteLength(value);
            if (!fullRequest.isStreamingSupported) {
              handler.send("DocProgress", {
                loaded,
                total: Math.max(loaded, fullRequest.contentLength || 0),
              });
            }

            if (newPdfManager) {
              newPdfManager.sendProgressiveData(value);
            } else {
              cachedChunks.push(value);
            }

            fullRequest.read().then(readChunk, reject);
          } catch (e) {
            reject(e);
          }
        };
        fullRequest.read().then(readChunk, reject);
      });
      readPromise.catch(function (e) {
        pdfManagerCapability.reject(e);
        cancelXHRs = null;
      });

      cancelXHRs = function (reason) {
        pdfStream.cancelAllRequests(reason);
      };

      return pdfManagerCapability.promise;
    }

    function setupDoc(data) {
      function onSuccess(doc) {
        ensureNotTerminated();
        handler.send("GetDoc", { pdfInfo: doc });
      }

      function onFailure(ex) {
        ensureNotTerminated();

        if (ex instanceof PasswordException) {
          const task = new WorkerTask(`PasswordException: response ${ex.code}`);
          startWorkerTask(task);

          handler
            .sendWithPromise("PasswordRequest", ex)
            .then(function ({ password }) {
              finishWorkerTask(task);
              pdfManager.updatePassword(password);
              pdfManagerReady();
            })
            .catch(function () {
              finishWorkerTask(task);
              handler.send("DocException", ex);
            });
        } else if (
          ex instanceof InvalidPDFException ||
          ex instanceof MissingPDFException ||
          ex instanceof UnexpectedResponseException ||
          ex instanceof UnknownErrorException
        ) {
          handler.send("DocException", ex);
        } else {
          handler.send(
            "DocException",
            new UnknownErrorException(ex.message, ex.toString())
          );
        }
      }

      function pdfManagerReady() {
        ensureNotTerminated();

        loadDocument(false).then(onSuccess, function (reason) {
          ensureNotTerminated();

          // Try again with recoveryMode == true
          if (!(reason instanceof XRefParseException)) {
            onFailure(reason);
            return;
          }
          pdfManager.requestLoadedStream();
          pdfManager.onLoadedStream().then(function () {
            ensureNotTerminated();

            loadDocument(true).then(onSuccess, onFailure);
          });
        });
      }

      ensureNotTerminated();

      const evaluatorOptions = {
        maxImageSize: data.maxImageSize,
        disableFontFace: data.disableFontFace,
        ignoreErrors: data.ignoreErrors,
        isEvalSupported: data.isEvalSupported,
        fontExtraProperties: data.fontExtraProperties,
        useSystemFonts: data.useSystemFonts,
        cMapUrl: data.cMapUrl,
        standardFontDataUrl: data.standardFontDataUrl,
      };

      getPdfManager(data, evaluatorOptions, data.enableXfa)
        .then(function (newPdfManager) {
          if (terminated) {
            // We were in a process of setting up the manager, but it got
            // terminated in the middle.
            newPdfManager.terminate(
              new AbortException("Worker was terminated.")
            );
            throw new Error("Worker was terminated");
          }
          pdfManager = newPdfManager;

          pdfManager.onLoadedStream().then(function (stream) {
            handler.send("DataLoaded", { length: stream.bytes.byteLength });
          });
        })
        .then(pdfManagerReady, onFailure);
    }

    handler.on("GetPage", function wphSetupGetPage(data) {
      return pdfManager.getPage(data.pageIndex).then(function (page) {
        return Promise.all([
          pdfManager.ensure(page, "rotate"),
          pdfManager.ensure(page, "ref"),
          pdfManager.ensure(page, "userUnit"),
          pdfManager.ensure(page, "view"),
        ]).then(function ([rotate, ref, userUnit, view]) {
          return {
            rotate,
            ref,
            userUnit,
            view,
          };
        });
      });
    });

    handler.on("GetPageIndex", function wphSetupGetPageIndex({ ref }) {
      const pageRef = Ref.get(ref.num, ref.gen);
      return pdfManager.ensureCatalog("getPageIndex", [pageRef]);
    });

    handler.on("GetDestinations", function wphSetupGetDestinations(data) {
      return pdfManager.ensureCatalog("destinations");
    });

    handler.on("GetDestination", function wphSetupGetDestination(data) {
      return pdfManager.ensureCatalog("getDestination", [data.id]);
    });

    handler.on("GetPageLabels", function wphSetupGetPageLabels(data) {
      return pdfManager.ensureCatalog("pageLabels");
    });

    handler.on("GetPageLayout", function wphSetupGetPageLayout(data) {
      return pdfManager.ensureCatalog("pageLayout");
    });

    handler.on("GetPageMode", function wphSetupGetPageMode(data) {
      return pdfManager.ensureCatalog("pageMode");
    });

    handler.on("GetViewerPreferences", function (data) {
      return pdfManager.ensureCatalog("viewerPreferences");
    });

    handler.on("GetOpenAction", function (data) {
      return pdfManager.ensureCatalog("openAction");
    });

    handler.on("GetAttachments", function wphSetupGetAttachments(data) {
      return pdfManager.ensureCatalog("attachments");
    });

    handler.on("GetJavaScript", function wphSetupGetJavaScript(data) {
      return pdfManager.ensureCatalog("javaScript");
    });

    handler.on("GetDocJSActions", function wphSetupGetDocJSActions(data) {
      return pdfManager.ensureCatalog("jsActions");
    });

    handler.on("GetPageJSActions", function ({ pageIndex }) {
      return pdfManager.getPage(pageIndex).then(function (page) {
        return pdfManager.ensure(page, "jsActions");
      });
    });

    handler.on("GetOutline", function wphSetupGetOutline(data) {
      return pdfManager.ensureCatalog("documentOutline");
    });

    handler.on("GetOptionalContentConfig", function (data) {
      return pdfManager.ensureCatalog("optionalContentConfig");
    });

    handler.on("GetPermissions", function (data) {
      return pdfManager.ensureCatalog("permissions");
    });

    handler.on("GetMetadata", function wphSetupGetMetadata(data) {
      return Promise.all([
        pdfManager.ensureDoc("documentInfo"),
        pdfManager.ensureCatalog("metadata"),
      ]);
    });

    handler.on("GetMarkInfo", function wphSetupGetMarkInfo(data) {
      return pdfManager.ensureCatalog("markInfo");
    });

    handler.on("GetData", function wphSetupGetData(data) {
      pdfManager.requestLoadedStream();
      return pdfManager.onLoadedStream().then(function (stream) {
        return stream.bytes;
      });
    });

    handler.on("GetStats", function wphSetupGetStats(data) {
      return pdfManager.ensureXRef("stats");
    });

    handler.on("GetAnnotations", function ({ pageIndex, intent }) {
      return pdfManager.getPage(pageIndex).then(function (page) {
        return page.getAnnotationsData(intent);
      });
    });

    handler.on("GetFieldObjects", function (data) {
      return pdfManager.ensureDoc("fieldObjects");
    });

    handler.on("HasJSActions", function (data) {
      return pdfManager.ensureDoc("hasJSActions");
    });

    handler.on("GetCalculationOrderIds", function (data) {
      return pdfManager.ensureDoc("calculationOrderIds");
    });

    handler.on(
      "SaveDocument",
      function ({ isPureXfa, numPages, annotationStorage, filename }) {
        pdfManager.requestLoadedStream();

        const promises = [
          pdfManager.onLoadedStream(),
          pdfManager.ensureCatalog("acroForm"),
          pdfManager.ensureCatalog("acroFormRef"),
          pdfManager.ensureDoc("xref"),
          pdfManager.ensureDoc("startXRef"),
        ];

        if (isPureXfa) {
          promises.push(pdfManager.serializeXfaData(annotationStorage));
        } else {
          for (let pageIndex = 0; pageIndex < numPages; pageIndex++) {
            promises.push(
              pdfManager.getPage(pageIndex).then(function (page) {
                const task = new WorkerTask(`Save: page ${pageIndex}`);
                return page
                  .save(handler, task, annotationStorage)
                  .finally(function () {
                    finishWorkerTask(task);
                  });
              })
            );
          }
        }

        return Promise.all(promises).then(function ([
          stream,
          acroForm,
          acroFormRef,
          xref,
          startXRef,
          ...refs
        ]) {
          let newRefs = [];
          let xfaData = null;
          if (isPureXfa) {
            xfaData = refs[0];
            if (!xfaData) {
              return stream.bytes;
            }
          } else {
            for (const ref of refs) {
              newRefs = ref
                .filter(x => x !== null)
                .reduce((a, b) => a.concat(b), newRefs);
            }

            if (newRefs.length === 0) {
              // No new refs so just return the initial bytes
              return stream.bytes;
            }
          }

          const xfa = (acroForm instanceof Dict && acroForm.get("XFA")) || null;
          let xfaDatasets = null;
          let hasDatasets = false;
          if (Array.isArray(xfa)) {
            for (let i = 0, ii = xfa.length; i < ii; i += 2) {
              if (xfa[i] === "datasets") {
                xfaDatasets = xfa[i + 1];
                acroFormRef = null;
                hasDatasets = true;
              }
            }
            if (xfaDatasets === null) {
              xfaDatasets = xref.getNewRef();
            }
          } else {
            acroFormRef = null;
            // TODO: Support XFA streams.
            warn("Unsupported XFA type.");
          }

          let newXrefInfo = Object.create(null);
          if (xref.trailer) {
            // Get string info from Info in order to compute fileId.
            const infoObj = Object.create(null);
            const xrefInfo = xref.trailer.get("Info") || null;
            if (xrefInfo instanceof Dict) {
              xrefInfo.forEach((key, value) => {
                if (isString(key) && isString(value)) {
                  infoObj[key] = stringToPDFString(value);
                }
              });
            }

            newXrefInfo = {
              rootRef: xref.trailer.getRaw("Root") || null,
              encryptRef: xref.trailer.getRaw("Encrypt") || null,
              newRef: xref.getNewRef(),
              infoRef: xref.trailer.getRaw("Info") || null,
              info: infoObj,
              fileIds: xref.trailer.get("ID") || null,
              startXRef,
              filename,
            };
          }
          xref.resetNewRef();

          return incrementalUpdate({
            originalData: stream.bytes,
            xrefInfo: newXrefInfo,
            newRefs,
            xref,
            datasetsRef: xfaDatasets,
            hasDatasets,
            acroFormRef,
            acroForm,
            xfaData,
          });
        });
      }
    );

    handler.on("GetOperatorList", function wphSetupRenderPage(data, sink) {
      const pageIndex = data.pageIndex;
      pdfManager.getPage(pageIndex).then(function (page) {
        const task = new WorkerTask(`GetOperatorList: page ${pageIndex}`);
        startWorkerTask(task);

        // NOTE: Keep this condition in sync with the `info` helper function.
        const start = verbosity >= VerbosityLevel.INFOS ? Date.now() : 0;

        // Pre compile the pdf page and fetch the fonts/images.
        page
          .getOperatorList({
            handler,
            sink,
            task,
            intent: data.intent,
            cacheKey: data.cacheKey,
            annotationStorage: data.annotationStorage,
          })
          .then(
            function (operatorListInfo) {
              finishWorkerTask(task);

              if (start) {
                info(
                  `page=${pageIndex + 1} - getOperatorList: time=` +
                    `${Date.now() - start}ms, len=${operatorListInfo.length}`
                );
              }
              sink.close();
            },
            function (reason) {
              finishWorkerTask(task);
              if (task.terminated) {
                return; // ignoring errors from the terminated thread
              }
              // For compatibility with older behavior, generating unknown
              // unsupported feature notification on errors.
              handler.send("UnsupportedFeature", {
                featureId: UNSUPPORTED_FEATURES.errorOperatorList,
              });

              sink.error(reason);

              // TODO: Should `reason` be re-thrown here (currently that casues
              //       "Uncaught exception: ..." messages in the console)?
            }
          );
      });
    });

    handler.on("GetTextContent", function wphExtractText(data, sink) {
      const pageIndex = data.pageIndex;
      sink.onPull = function (desiredSize) {};
      sink.onCancel = function (reason) {};

      pdfManager.getPage(pageIndex).then(function (page) {
        const task = new WorkerTask("GetTextContent: page " + pageIndex);
        startWorkerTask(task);

        // NOTE: Keep this condition in sync with the `info` helper function.
        const start = verbosity >= VerbosityLevel.INFOS ? Date.now() : 0;

        page
          .extractTextContent({
            handler,
            task,
            sink,
            normalizeWhitespace: data.normalizeWhitespace,
            includeMarkedContent: data.includeMarkedContent,
            combineTextItems: data.combineTextItems,
          })
          .then(
            function () {
              finishWorkerTask(task);

              if (start) {
                info(
                  `page=${pageIndex + 1} - getTextContent: time=` +
                    `${Date.now() - start}ms`
                );
              }
              sink.close();
            },
            function (reason) {
              finishWorkerTask(task);
              if (task.terminated) {
                return; // ignoring errors from the terminated thread
              }
              sink.error(reason);

              // TODO: Should `reason` be re-thrown here (currently that casues
              //       "Uncaught exception: ..." messages in the console)?
            }
          );
      });
    });

    handler.on("GetStructTree", function wphGetStructTree(data) {
      return pdfManager.getPage(data.pageIndex).then(function (page) {
        return pdfManager.ensure(page, "getStructTree");
      });
    });

    handler.on("FontFallback", function (data) {
      return pdfManager.fontFallback(data.id, handler);
    });

    handler.on("Cleanup", function wphCleanup(data) {
      return pdfManager.cleanup(/* manuallyTriggered = */ true);
    });

    handler.on("Terminate", function wphTerminate(data) {
      terminated = true;

      const waitOn = [];
      if (pdfManager) {
        pdfManager.terminate(new AbortException("Worker was terminated."));

        const cleanupPromise = pdfManager.cleanup();
        waitOn.push(cleanupPromise);

        pdfManager = null;
      } else {
        clearPrimitiveCaches();
      }
      if (cancelXHRs) {
        cancelXHRs(new AbortException("Worker was terminated."));
      }

      for (const task of WorkerTasks) {
        waitOn.push(task.finished);
        task.terminate();
      }

      return Promise.all(waitOn).then(function () {
        // Notice that even if we destroying handler, resolved response promise
        // must be sent back.
        handler.destroy();
        handler = null;
      });
    });

    handler.on("Ready", function wphReady(data) {
      setupDoc(docParams);
      docParams = null; // we don't need docParams anymore -- saving memory.
    });
    return workerHandlerName;
  }

  static initializeFromPort(port) {
    const handler = new MessageHandler("worker", "main", port);
    WorkerMessageHandler.setup(handler, port);
    handler.send("ready", null);
  }
}

function isMessagePort(maybePort) {
  return (
    typeof maybePort.postMessage === "function" && "onmessage" in maybePort
  );
}

// Worker thread (and not Node.js)?
if (
  typeof window === "undefined" &&
  !isNodeJS &&
  typeof self !== "undefined" &&
  isMessagePort(self)
) {
  WorkerMessageHandler.initializeFromPort(self);
}

export { WorkerMessageHandler, WorkerTask };