Implement a permissions API

src/core/obj.js

@@ -15,9 +15,9 @@
 
 import {
  bytesToString, createPromiseCapability, createValidAbsoluteUrl, FormatError,
- info, InvalidPDFException, isBool, isString, MissingDataException, shadow,
- stringToPDFString, stringToUTF8String, toRomanNumerals, unreachable, warn,
- XRefParseException
+ info, InvalidPDFException, isBool, isNum, isString, MissingDataException,
+ PermissionFlag, shadow, stringToPDFString, stringToUTF8String,
+ toRomanNumerals, unreachable, warn, XRefParseException
 } from '../shared/util';
 import {
  Dict, isCmd, isDict, isName, isRef, isRefsEqual, isStream, Ref, RefSet,
@@ -177,6 +177,48 @@ class Catalog {
  return (root.items.length > 0 ? root.items : null);
  }
 
+ get permissions() {
+ let permissions = null;
+ try {
+ permissions = this._readPermissions();
+ } catch (ex) {
+ if (ex instanceof MissingDataException) {
+ throw ex;
+ }
+ warn('Unable to read permissions.');
+ }
+ return shadow(this, 'permissions', permissions);
+ }
+
+ /**
+ * @private
+ */
+ _readPermissions() {
+ const encrypt = this.xref.trailer.get('Encrypt');
+ if (!isDict(encrypt)) {
+ return null;
+ }
+
+ let flags = encrypt.get('P');
+ if (!isNum(flags)) {
+ return null;
+ }
+
+ // PDF integer objects are represented internally in signed 2's complement
+ // form. Therefore, convert the signed decimal integer to a signed 2's
+ // complement binary integer so we can use regular bitwise operations on it.
+ flags += 2 ** 32;
+
+ const permissions = [];
+ for (const key in PermissionFlag) {
+ const value = PermissionFlag[key];
+ if (flags & value) {
+ permissions.push(value);
+ }
+ }
+ return permissions;
+ }
+
  get numPages() {
  const obj = this.toplevelPagesDict.get('Count');
  if (!Number.isInteger(obj)) {

src/core/worker.js

@@ -703,6 +703,10 @@ var WorkerMessageHandler = {
  }
  );
 
+ handler.on('GetPermissions', function(data) {
+ return pdfManager.ensureCatalog('permissions');
+ });
+
  handler.on('GetMetadata',
  function wphSetupGetMetadata(data) {
  return Promise.all([pdfManager.ensureDoc('documentInfo'),

src/display/api.js

@@ -691,6 +691,14 @@ class PDFDocumentProxy {
  return this._transport.getOutline();
  }
 
+ /**
+ * @return {Promise} A promise that is resolved with an {Array} that contains
+ * the permission flags for the PDF document.
+ */
+ getPermissions() {
+ return this._transport.getPermissions();
+ }
+
  /**
  * @return {Promise} A promise that is resolved with an {Object} that has
  * `info` and `metadata` properties. `info` is an {Object} filled with
@@ -2142,6 +2150,10 @@ class WorkerTransport {
  return this.messageHandler.sendWithPromise('GetOutline', null);
  }
 
+ getPermissions() {
+ return this.messageHandler.sendWithPromise('GetPermissions', null);
+ }
+
  getMetadata() {
  return this.messageHandler.sendWithPromise('GetMetadata', null).
  then((results) => {

src/shared/util.js

@@ -25,6 +25,18 @@ const NativeImageDecoding = {
  DISPLAY: 'display',
 };
 
+// Permission flags from Table 22, Section 7.6.3.2 of the PDF specification.
+const PermissionFlag = {
+ PRINT: 0x04,
+ MODIFY_CONTENTS: 0x08,
+ COPY: 0x10,
+ MODIFY_ANNOTATIONS: 0x20,
+ FILL_INTERACTIVE_FORMS: 0x100,
+ COPY_FOR_ACCESSIBILITY: 0x200,
+ ASSEMBLE: 0x400,
+ PRINT_HIGH_QUALITY: 0x800,
+};
+
 var TextRenderingMode = {
  FILL: 0,
  STROKE: 1,
@@ -1014,6 +1026,7 @@ export {
  NativeImageDecoding,
  PasswordException,
  PasswordResponses,
+ PermissionFlag,
  StreamType,
  TextRenderingMode,
  UnexpectedResponseException,

test/pdfs/.gitignore

@@ -324,3 +324,6 @@
 !transparent.pdf
 !xobject-image.pdf
 !ccitt_EndOfBlock_false.pdf
+!issue9972-1.pdf
+!issue9972-2.pdf
+!issue9972-3.pdf

test/unit/api_spec.js

@@ -18,7 +18,8 @@ import {
 } from './test_utils';
 import {
  createPromiseCapability, FontType, InvalidPDFException, MissingPDFException,
- OPS, PasswordException, PasswordResponses, StreamType, stringToBytes
+ OPS, PasswordException, PasswordResponses, PermissionFlag, StreamType,
+ stringToBytes
 } from '../../src/shared/util';
 import {
  DOMCanvasFactory, RenderingCancelledException, StatTimer
@@ -822,6 +823,63 @@ describe('api', function() {
  done.fail(reason);
  });
  });
+
+ it('gets non-existent permissions', function(done) {
+ doc.getPermissions().then(function(permissions) {
+ expect(permissions).toEqual(null);
+
+ done();
+ }).catch(function(reason) {
+ done.fail(reason);
+ });
+ });
+
+ it('gets permissions', function (done) {
+ // Editing not allowed.
+ const loadingTask0 =
+ getDocument(buildGetDocumentParams('issue9972-1.pdf'));
+ const promise0 = loadingTask0.promise.then(function(pdfDocument) {
+ return pdfDocument.getPermissions();
+ });
+
+ // Printing not allowed.
+ const loadingTask1 =
+ getDocument(buildGetDocumentParams('issue9972-2.pdf'));
+ const promise1 = loadingTask1.promise.then(function(pdfDocument) {
+ return pdfDocument.getPermissions();
+ });
+
+ // Copying not allowed.
+ const loadingTask2 =
+ getDocument(buildGetDocumentParams('issue9972-3.pdf'));
+ const promise2 = loadingTask2.promise.then(function(pdfDocument) {
+ return pdfDocument.getPermissions();
+ });
+
+ const totalPermissionCount = Object.keys(PermissionFlag).length;
+ Promise.all([promise0, promise1, promise2]).then(function(permissions) {
+ expect(permissions[0].length).toEqual(totalPermissionCount - 1);
+ expect(permissions[0].includes(PermissionFlag.MODIFY_CONTENTS))
+ .toBeFalsy();
+
+ expect(permissions[1].length).toEqual(totalPermissionCount - 2);
+ expect(permissions[1].includes(PermissionFlag.PRINT)).toBeFalsy();
+ expect(permissions[1].includes(PermissionFlag.PRINT_HIGH_QUALITY))
+ .toBeFalsy();
+
+ expect(permissions[2].length).toEqual(totalPermissionCount - 1);
+ expect(permissions[2].includes(PermissionFlag.COPY)).toBeFalsy();
+
+ Promise.all([
+ loadingTask0.destroy(),
+ loadingTask1.destroy(),
+ loadingTask2.destroy(),
+ ]).then(done);
+ }).catch(function(reason) {
+ done.fail(reason);
+ });
+ });
+
  it('gets metadata', function(done) {
  var promise = doc.getMetadata();
  promise.then(function({ info, metadata, contentDispositionFilename, }) {