Move the XRef from src/core/obj.js and into its own file
The size of the `src/core/obj.js` file has increased slowly over the years, and it also contains a fair amount of *distinct* functionality. In order to improve readability and make it easier to navigate through the code, this patch moves the `XRef` into its own file.
This commit is contained in:
Jonas Jenwald
parent
24e5ecdf76
commit
e8750cfe95
@ -34,7 +34,6 @@ import {
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Util,
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Util,
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warn,
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warn,
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} from "../shared/util.js";
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} from "../shared/util.js";
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import { Catalog, XRef } from "./obj.js";
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import {
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import {
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clearPrimitiveCaches,
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clearPrimitiveCaches,
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Dict,
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Dict,
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@ -55,12 +54,14 @@ import {
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import { NullStream, Stream, StreamsSequenceStream } from "./stream.js";
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import { NullStream, Stream, StreamsSequenceStream } from "./stream.js";
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import { AnnotationFactory } from "./annotation.js";
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import { AnnotationFactory } from "./annotation.js";
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import { calculateMD5 } from "./crypto.js";
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import { calculateMD5 } from "./crypto.js";
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import { Catalog } from "./obj.js";
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import { Linearization } from "./parser.js";
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import { Linearization } from "./parser.js";
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import { ObjectLoader } from "./object_loader.js";
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import { ObjectLoader } from "./object_loader.js";
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import { OperatorList } from "./operator_list.js";
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import { OperatorList } from "./operator_list.js";
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import { PartialEvaluator } from "./evaluator.js";
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import { PartialEvaluator } from "./evaluator.js";
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import { StructTreePage } from "./struct_tree.js";
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import { StructTreePage } from "./struct_tree.js";
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import { XFAFactory } from "./xfa/factory.js";
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import { XFAFactory } from "./xfa/factory.js";
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import { XRef } from "./xref.js";
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const DEFAULT_USER_UNIT = 1.0;
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const DEFAULT_USER_UNIT = 1.0;
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const LETTER_SIZE_MEDIABOX = [0, 0, 612, 792];
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const LETTER_SIZE_MEDIABOX = [0, 0, 612, 792];
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856
src/core/obj.js
856
src/core/obj.js
@ -12,17 +12,14 @@
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* See the License for the specific language governing permissions and
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* See the License for the specific language governing permissions and
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* limitations under the License.
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* limitations under the License.
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*/
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*/
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/* eslint-disable no-var */
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import {
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import {
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assert,
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bytesToString,
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bytesToString,
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createPromiseCapability,
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createPromiseCapability,
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createValidAbsoluteUrl,
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createValidAbsoluteUrl,
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DocumentActionEventType,
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DocumentActionEventType,
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FormatError,
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FormatError,
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info,
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info,
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InvalidPDFException,
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isBool,
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isBool,
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isNum,
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isNum,
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isString,
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isString,
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@ -35,15 +32,12 @@ import {
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} from "../shared/util.js";
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} from "../shared/util.js";
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import {
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import {
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clearPrimitiveCaches,
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clearPrimitiveCaches,
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Cmd,
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Dict,
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Dict,
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isCmd,
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isDict,
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isDict,
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isName,
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isName,
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isRef,
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isRef,
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isRefsEqual,
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isRefsEqual,
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isStream,
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isStream,
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Ref,
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RefSet,
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RefSet,
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RefSetCache,
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RefSetCache,
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} from "./primitives.js";
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} from "./primitives.js";
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@ -51,12 +45,8 @@ import {
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collectActions,
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collectActions,
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MissingDataException,
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MissingDataException,
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toRomanNumerals,
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toRomanNumerals,
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XRefEntryException,
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XRefParseException,
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} from "./core_utils.js";
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} from "./core_utils.js";
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import { Lexer, Parser } from "./parser.js";
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import { NameTree, NumberTree } from "./name_number_tree.js";
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import { NameTree, NumberTree } from "./name_number_tree.js";
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import { CipherTransformFactory } from "./crypto.js";
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import { ColorSpace } from "./colorspace.js";
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import { ColorSpace } from "./colorspace.js";
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import { FileSpec } from "./file_spec.js";
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import { FileSpec } from "./file_spec.js";
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import { GlobalImageCache } from "./image_utils.js";
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import { GlobalImageCache } from "./image_utils.js";
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@ -1426,848 +1416,4 @@ class Catalog {
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}
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}
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}
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}
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var XRef = (function XRefClosure() {
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export { Catalog };
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// eslint-disable-next-line no-shadow
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function XRef(stream, pdfManager) {
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this.stream = stream;
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this.pdfManager = pdfManager;
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this.entries = [];
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this.xrefstms = Object.create(null);
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this._cacheMap = new Map(); // Prepare the XRef cache.
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this.stats = {
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streamTypes: Object.create(null),
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fontTypes: Object.create(null),
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};
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this._newRefNum = null;
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}
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XRef.prototype = {
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getNewRef: function XRef_getNewRef() {
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if (this._newRefNum === null) {
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this._newRefNum = this.entries.length;
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}
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return Ref.get(this._newRefNum++, 0);
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},
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resetNewRef: function XRef_resetNewRef() {
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this._newRefNum = null;
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},
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setStartXRef: function XRef_setStartXRef(startXRef) {
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// Store the starting positions of xref tables as we process them
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// so we can recover from missing data errors
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this.startXRefQueue = [startXRef];
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},
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parse: function XRef_parse(recoveryMode) {
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var trailerDict;
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if (!recoveryMode) {
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trailerDict = this.readXRef();
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} else {
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warn("Indexing all PDF objects");
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trailerDict = this.indexObjects();
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}
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trailerDict.assignXref(this);
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this.trailer = trailerDict;
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let encrypt;
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try {
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encrypt = trailerDict.get("Encrypt");
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} catch (ex) {
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if (ex instanceof MissingDataException) {
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throw ex;
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}
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warn(`XRef.parse - Invalid "Encrypt" reference: "${ex}".`);
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}
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if (isDict(encrypt)) {
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var ids = trailerDict.get("ID");
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var fileId = ids && ids.length ? ids[0] : "";
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// The 'Encrypt' dictionary itself should not be encrypted, and by
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// setting `suppressEncryption` we can prevent an infinite loop inside
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// of `XRef_fetchUncompressed` if the dictionary contains indirect
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// objects (fixes issue7665.pdf).
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encrypt.suppressEncryption = true;
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this.encrypt = new CipherTransformFactory(
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encrypt,
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fileId,
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this.pdfManager.password
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);
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}
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// Get the root dictionary (catalog) object, and do some basic validation.
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let root;
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try {
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root = trailerDict.get("Root");
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} catch (ex) {
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if (ex instanceof MissingDataException) {
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throw ex;
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}
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warn(`XRef.parse - Invalid "Root" reference: "${ex}".`);
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}
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if (isDict(root) && root.has("Pages")) {
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this.root = root;
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} else {
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if (!recoveryMode) {
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throw new XRefParseException();
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}
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throw new FormatError("Invalid root reference");
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}
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},
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processXRefTable: function XRef_processXRefTable(parser) {
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if (!("tableState" in this)) {
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// Stores state of the table as we process it so we can resume
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// from middle of table in case of missing data error
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this.tableState = {
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entryNum: 0,
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streamPos: parser.lexer.stream.pos,
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parserBuf1: parser.buf1,
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parserBuf2: parser.buf2,
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};
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}
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var obj = this.readXRefTable(parser);
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// Sanity check
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if (!isCmd(obj, "trailer")) {
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throw new FormatError(
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"Invalid XRef table: could not find trailer dictionary"
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);
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}
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// Read trailer dictionary, e.g.
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// trailer
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// << /Size 22
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// /Root 20R
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// /Info 10R
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// /ID [ <81b14aafa313db63dbd6f981e49f94f4> ]
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// >>
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// The parser goes through the entire stream << ... >> and provides
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// a getter interface for the key-value table
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var dict = parser.getObj();
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// The pdflib PDF generator can generate a nested trailer dictionary
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if (!isDict(dict) && dict.dict) {
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dict = dict.dict;
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}
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if (!isDict(dict)) {
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throw new FormatError(
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"Invalid XRef table: could not parse trailer dictionary"
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);
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}
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delete this.tableState;
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return dict;
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},
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readXRefTable: function XRef_readXRefTable(parser) {
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// Example of cross-reference table:
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// xref
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// 0 1 <-- subsection header (first obj #, obj count)
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// 0000000000 65535 f <-- actual object (offset, generation #, f/n)
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// 23 2 <-- subsection header ... and so on ...
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// 0000025518 00002 n
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// 0000025635 00000 n
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// trailer
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// ...
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var stream = parser.lexer.stream;
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var tableState = this.tableState;
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stream.pos = tableState.streamPos;
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parser.buf1 = tableState.parserBuf1;
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parser.buf2 = tableState.parserBuf2;
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// Outer loop is over subsection headers
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var obj;
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while (true) {
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if (!("firstEntryNum" in tableState) || !("entryCount" in tableState)) {
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if (isCmd((obj = parser.getObj()), "trailer")) {
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break;
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}
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tableState.firstEntryNum = obj;
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tableState.entryCount = parser.getObj();
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}
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var first = tableState.firstEntryNum;
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var count = tableState.entryCount;
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if (!Number.isInteger(first) || !Number.isInteger(count)) {
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throw new FormatError(
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"Invalid XRef table: wrong types in subsection header"
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);
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}
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// Inner loop is over objects themselves
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for (var i = tableState.entryNum; i < count; i++) {
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tableState.streamPos = stream.pos;
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tableState.entryNum = i;
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tableState.parserBuf1 = parser.buf1;
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tableState.parserBuf2 = parser.buf2;
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var entry = {};
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entry.offset = parser.getObj();
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entry.gen = parser.getObj();
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var type = parser.getObj();
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if (type instanceof Cmd) {
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switch (type.cmd) {
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case "f":
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entry.free = true;
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break;
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case "n":
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entry.uncompressed = true;
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break;
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}
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}
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// Validate entry obj
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if (
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!Number.isInteger(entry.offset) ||
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!Number.isInteger(entry.gen) ||
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!(entry.free || entry.uncompressed)
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) {
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throw new FormatError(
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`Invalid entry in XRef subsection: ${first}, ${count}`
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);
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}
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// The first xref table entry, i.e. obj 0, should be free. Attempting
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// to adjust an incorrect first obj # (fixes issue 3248 and 7229).
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if (i === 0 && entry.free && first === 1) {
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first = 0;
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}
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if (!this.entries[i + first]) {
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this.entries[i + first] = entry;
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}
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}
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tableState.entryNum = 0;
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tableState.streamPos = stream.pos;
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tableState.parserBuf1 = parser.buf1;
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tableState.parserBuf2 = parser.buf2;
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delete tableState.firstEntryNum;
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delete tableState.entryCount;
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}
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// Sanity check: as per spec, first object must be free
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if (this.entries[0] && !this.entries[0].free) {
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throw new FormatError("Invalid XRef table: unexpected first object");
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}
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return obj;
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},
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processXRefStream: function XRef_processXRefStream(stream) {
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if (!("streamState" in this)) {
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// Stores state of the stream as we process it so we can resume
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// from middle of stream in case of missing data error
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var streamParameters = stream.dict;
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var byteWidths = streamParameters.get("W");
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var range = streamParameters.get("Index");
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if (!range) {
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range = [0, streamParameters.get("Size")];
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}
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this.streamState = {
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entryRanges: range,
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byteWidths,
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entryNum: 0,
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streamPos: stream.pos,
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};
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}
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this.readXRefStream(stream);
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delete this.streamState;
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return stream.dict;
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},
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readXRefStream: function XRef_readXRefStream(stream) {
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var i, j;
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var streamState = this.streamState;
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stream.pos = streamState.streamPos;
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var byteWidths = streamState.byteWidths;
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var typeFieldWidth = byteWidths[0];
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var offsetFieldWidth = byteWidths[1];
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var generationFieldWidth = byteWidths[2];
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var entryRanges = streamState.entryRanges;
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while (entryRanges.length > 0) {
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var first = entryRanges[0];
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var n = entryRanges[1];
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if (!Number.isInteger(first) || !Number.isInteger(n)) {
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throw new FormatError(`Invalid XRef range fields: ${first}, ${n}`);
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}
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if (
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!Number.isInteger(typeFieldWidth) ||
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!Number.isInteger(offsetFieldWidth) ||
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!Number.isInteger(generationFieldWidth)
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) {
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throw new FormatError(
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`Invalid XRef entry fields length: ${first}, ${n}`
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);
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}
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for (i = streamState.entryNum; i < n; ++i) {
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streamState.entryNum = i;
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streamState.streamPos = stream.pos;
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var type = 0,
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offset = 0,
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generation = 0;
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for (j = 0; j < typeFieldWidth; ++j) {
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type = (type << 8) | stream.getByte();
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}
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// if type field is absent, its default value is 1
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if (typeFieldWidth === 0) {
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type = 1;
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}
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for (j = 0; j < offsetFieldWidth; ++j) {
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offset = (offset << 8) | stream.getByte();
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}
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for (j = 0; j < generationFieldWidth; ++j) {
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generation = (generation << 8) | stream.getByte();
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}
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var entry = {};
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entry.offset = offset;
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entry.gen = generation;
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switch (type) {
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case 0:
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entry.free = true;
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||||||
break;
|
|
||||||
case 1:
|
|
||||||
entry.uncompressed = true;
|
|
||||||
break;
|
|
||||||
case 2:
|
|
||||||
break;
|
|
||||||
default:
|
|
||||||
throw new FormatError(`Invalid XRef entry type: ${type}`);
|
|
||||||
}
|
|
||||||
if (!this.entries[first + i]) {
|
|
||||||
this.entries[first + i] = entry;
|
|
||||||
}
|
|
||||||
}
|
|
||||||
|
|
||||||
streamState.entryNum = 0;
|
|
||||||
streamState.streamPos = stream.pos;
|
|
||||||
entryRanges.splice(0, 2);
|
|
||||||
}
|
|
||||||
},
|
|
||||||
|
|
||||||
indexObjects: function XRef_indexObjects() {
|
|
||||||
// Simple scan through the PDF content to find objects,
|
|
||||||
// trailers and XRef streams.
|
|
||||||
var TAB = 0x9,
|
|
||||||
LF = 0xa,
|
|
||||||
CR = 0xd,
|
|
||||||
SPACE = 0x20;
|
|
||||||
var PERCENT = 0x25,
|
|
||||||
LT = 0x3c;
|
|
||||||
|
|
||||||
function readToken(data, offset) {
|
|
||||||
var token = "",
|
|
||||||
ch = data[offset];
|
|
||||||
while (ch !== LF && ch !== CR && ch !== LT) {
|
|
||||||
if (++offset >= data.length) {
|
|
||||||
break;
|
|
||||||
}
|
|
||||||
token += String.fromCharCode(ch);
|
|
||||||
ch = data[offset];
|
|
||||||
}
|
|
||||||
return token;
|
|
||||||
}
|
|
||||||
function skipUntil(data, offset, what) {
|
|
||||||
var length = what.length,
|
|
||||||
dataLength = data.length;
|
|
||||||
var skipped = 0;
|
|
||||||
// finding byte sequence
|
|
||||||
while (offset < dataLength) {
|
|
||||||
var i = 0;
|
|
||||||
while (i < length && data[offset + i] === what[i]) {
|
|
||||||
++i;
|
|
||||||
}
|
|
||||||
if (i >= length) {
|
|
||||||
break; // sequence found
|
|
||||||
}
|
|
||||||
offset++;
|
|
||||||
skipped++;
|
|
||||||
}
|
|
||||||
return skipped;
|
|
||||||
}
|
|
||||||
var objRegExp = /^(\d+)\s+(\d+)\s+obj\b/;
|
|
||||||
const endobjRegExp = /\bendobj[\b\s]$/;
|
|
||||||
const nestedObjRegExp = /\s+(\d+\s+\d+\s+obj[\b\s<])$/;
|
|
||||||
const CHECK_CONTENT_LENGTH = 25;
|
|
||||||
|
|
||||||
var trailerBytes = new Uint8Array([116, 114, 97, 105, 108, 101, 114]);
|
|
||||||
// prettier-ignore
|
|
||||||
var startxrefBytes = new Uint8Array([115, 116, 97, 114, 116, 120, 114,
|
|
||||||
101, 102]);
|
|
||||||
const objBytes = new Uint8Array([111, 98, 106]);
|
|
||||||
var xrefBytes = new Uint8Array([47, 88, 82, 101, 102]);
|
|
||||||
|
|
||||||
// Clear out any existing entries, since they may be bogus.
|
|
||||||
this.entries.length = 0;
|
|
||||||
|
|
||||||
var stream = this.stream;
|
|
||||||
stream.pos = 0;
|
|
||||||
var buffer = stream.getBytes();
|
|
||||||
var position = stream.start,
|
|
||||||
length = buffer.length;
|
|
||||||
var trailers = [],
|
|
||||||
xrefStms = [];
|
|
||||||
while (position < length) {
|
|
||||||
var ch = buffer[position];
|
|
||||||
if (ch === TAB || ch === LF || ch === CR || ch === SPACE) {
|
|
||||||
++position;
|
|
||||||
continue;
|
|
||||||
}
|
|
||||||
if (ch === PERCENT) {
|
|
||||||
// %-comment
|
|
||||||
do {
|
|
||||||
++position;
|
|
||||||
if (position >= length) {
|
|
||||||
break;
|
|
||||||
}
|
|
||||||
ch = buffer[position];
|
|
||||||
} while (ch !== LF && ch !== CR);
|
|
||||||
continue;
|
|
||||||
}
|
|
||||||
var token = readToken(buffer, position);
|
|
||||||
var m;
|
|
||||||
if (
|
|
||||||
token.startsWith("xref") &&
|
|
||||||
(token.length === 4 || /\s/.test(token[4]))
|
|
||||||
) {
|
|
||||||
position += skipUntil(buffer, position, trailerBytes);
|
|
||||||
trailers.push(position);
|
|
||||||
position += skipUntil(buffer, position, startxrefBytes);
|
|
||||||
} else if ((m = objRegExp.exec(token))) {
|
|
||||||
const num = m[1] | 0,
|
|
||||||
gen = m[2] | 0;
|
|
||||||
if (!this.entries[num] || this.entries[num].gen === gen) {
|
|
||||||
this.entries[num] = {
|
|
||||||
offset: position - stream.start,
|
|
||||||
gen,
|
|
||||||
uncompressed: true,
|
|
||||||
};
|
|
||||||
}
|
|
||||||
let contentLength,
|
|
||||||
startPos = position + token.length;
|
|
||||||
|
|
||||||
// Find the next "obj" string, rather than "endobj", to ensure that
|
|
||||||
// we won't skip over a new 'obj' operator in corrupt files where
|
|
||||||
// 'endobj' operators are missing (fixes issue9105_reduced.pdf).
|
|
||||||
while (startPos < buffer.length) {
|
|
||||||
const endPos = startPos + skipUntil(buffer, startPos, objBytes) + 4;
|
|
||||||
contentLength = endPos - position;
|
|
||||||
|
|
||||||
const checkPos = Math.max(endPos - CHECK_CONTENT_LENGTH, startPos);
|
|
||||||
const tokenStr = bytesToString(buffer.subarray(checkPos, endPos));
|
|
||||||
|
|
||||||
// Check if the current object ends with an 'endobj' operator.
|
|
||||||
if (endobjRegExp.test(tokenStr)) {
|
|
||||||
break;
|
|
||||||
} else {
|
|
||||||
// Check if an "obj" occurrence is actually a new object,
|
|
||||||
// i.e. the current object is missing the 'endobj' operator.
|
|
||||||
const objToken = nestedObjRegExp.exec(tokenStr);
|
|
||||||
|
|
||||||
if (objToken && objToken[1]) {
|
|
||||||
warn(
|
|
||||||
'indexObjects: Found new "obj" inside of another "obj", ' +
|
|
||||||
'caused by missing "endobj" -- trying to recover.'
|
|
||||||
);
|
|
||||||
contentLength -= objToken[1].length;
|
|
||||||
break;
|
|
||||||
}
|
|
||||||
}
|
|
||||||
startPos = endPos;
|
|
||||||
}
|
|
||||||
const content = buffer.subarray(position, position + contentLength);
|
|
||||||
|
|
||||||
// checking XRef stream suspect
|
|
||||||
// (it shall have '/XRef' and next char is not a letter)
|
|
||||||
var xrefTagOffset = skipUntil(content, 0, xrefBytes);
|
|
||||||
if (
|
|
||||||
xrefTagOffset < contentLength &&
|
|
||||||
content[xrefTagOffset + 5] < 64
|
|
||||||
) {
|
|
||||||
xrefStms.push(position - stream.start);
|
|
||||||
this.xrefstms[position - stream.start] = 1; // Avoid recursion
|
|
||||||
}
|
|
||||||
|
|
||||||
position += contentLength;
|
|
||||||
} else if (
|
|
||||||
token.startsWith("trailer") &&
|
|
||||||
(token.length === 7 || /\s/.test(token[7]))
|
|
||||||
) {
|
|
||||||
trailers.push(position);
|
|
||||||
position += skipUntil(buffer, position, startxrefBytes);
|
|
||||||
} else {
|
|
||||||
position += token.length + 1;
|
|
||||||
}
|
|
||||||
}
|
|
||||||
// reading XRef streams
|
|
||||||
for (let i = 0, ii = xrefStms.length; i < ii; ++i) {
|
|
||||||
this.startXRefQueue.push(xrefStms[i]);
|
|
||||||
this.readXRef(/* recoveryMode */ true);
|
|
||||||
}
|
|
||||||
// finding main trailer
|
|
||||||
let trailerDict;
|
|
||||||
for (let i = 0, ii = trailers.length; i < ii; ++i) {
|
|
||||||
stream.pos = trailers[i];
|
|
||||||
const parser = new Parser({
|
|
||||||
lexer: new Lexer(stream),
|
|
||||||
xref: this,
|
|
||||||
allowStreams: true,
|
|
||||||
recoveryMode: true,
|
|
||||||
});
|
|
||||||
var obj = parser.getObj();
|
|
||||||
if (!isCmd(obj, "trailer")) {
|
|
||||||
continue;
|
|
||||||
}
|
|
||||||
// read the trailer dictionary
|
|
||||||
const dict = parser.getObj();
|
|
||||||
if (!isDict(dict)) {
|
|
||||||
continue;
|
|
||||||
}
|
|
||||||
// Do some basic validation of the trailer/root dictionary candidate.
|
|
||||||
try {
|
|
||||||
const rootDict = dict.get("Root");
|
|
||||||
if (!(rootDict instanceof Dict)) {
|
|
||||||
continue;
|
|
||||||
}
|
|
||||||
const pagesDict = rootDict.get("Pages");
|
|
||||||
if (!(pagesDict instanceof Dict)) {
|
|
||||||
continue;
|
|
||||||
}
|
|
||||||
const pagesCount = pagesDict.get("Count");
|
|
||||||
if (!Number.isInteger(pagesCount)) {
|
|
||||||
continue;
|
|
||||||
}
|
|
||||||
// The top-level /Pages dictionary isn't obviously corrupt.
|
|
||||||
} catch (ex) {
|
|
||||||
continue;
|
|
||||||
}
|
|
||||||
// taking the first one with 'ID'
|
|
||||||
if (dict.has("ID")) {
|
|
||||||
return dict;
|
|
||||||
}
|
|
||||||
// The current dictionary is a candidate, but continue searching.
|
|
||||||
trailerDict = dict;
|
|
||||||
}
|
|
||||||
// No trailer with 'ID', taking last one (if exists).
|
|
||||||
if (trailerDict) {
|
|
||||||
return trailerDict;
|
|
||||||
}
|
|
||||||
// nothing helps
|
|
||||||
throw new InvalidPDFException("Invalid PDF structure.");
|
|
||||||
},
|
|
||||||
|
|
||||||
readXRef: function XRef_readXRef(recoveryMode) {
|
|
||||||
var stream = this.stream;
|
|
||||||
// Keep track of already parsed XRef tables, to prevent an infinite loop
|
|
||||||
// when parsing corrupt PDF files where e.g. the /Prev entries create a
|
|
||||||
// circular dependency between tables (fixes bug1393476.pdf).
|
|
||||||
const startXRefParsedCache = new Set();
|
|
||||||
|
|
||||||
try {
|
|
||||||
while (this.startXRefQueue.length) {
|
|
||||||
var startXRef = this.startXRefQueue[0];
|
|
||||||
|
|
||||||
if (startXRefParsedCache.has(startXRef)) {
|
|
||||||
warn("readXRef - skipping XRef table since it was already parsed.");
|
|
||||||