When updating, write the xref table in the same format as the previous one (bug 1878916)
The specs are unclear about what kind of xref table format must be used. In checking the validity of some pdfs in the preflight tool from Acrobat we can guess that having the same format is the correct way to do. The pdf in the mentioned bug, after having been changed, wasn't correctly displayed in neither Chrome nor Acrobat: it's now fixed.
This commit is contained in:
Calixte Denizet
parent
e60329cea1
commit
2133da166e
@ -611,6 +611,19 @@ function getRotationMatrix(rotation, width, height) {
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}
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}
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/**
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* Get the number of bytes to use to represent the given positive integer.
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* If n is zero, the function returns 0 which means that we don't need to waste
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* a byte to represent it.
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* @param {number} x - a positive integer.
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* @returns {number}
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*/
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function getSizeInBytes(x) {
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// n bits are required for numbers up to 2^n - 1.
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// So for a number x, we need ceil(log2(1 + x)) bits.
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return Math.ceil(Math.ceil(Math.log2(1 + x)) / 8);
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}
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export {
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arrayBuffersToBytes,
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codePointIter,
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@ -622,6 +635,7 @@ export {
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getLookupTableFactory,
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getNewAnnotationsMap,
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getRotationMatrix,
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getSizeInBytes,
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isAscii,
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isWhiteSpace,
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log2,
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@ -35,7 +35,7 @@ import {
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getNewAnnotationsMap,
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XRefParseException,
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} from "./core_utils.js";
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import { Dict, Ref } from "./primitives.js";
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import { Dict, isDict, Ref } from "./primitives.js";
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import { LocalPdfManager, NetworkPdfManager } from "./pdf_manager.js";
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import { AnnotationFactory } from "./annotation.js";
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import { clearGlobalCaches } from "./cleanup_helper.js";
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@ -726,6 +726,8 @@ class WorkerMessageHandler {
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acroFormRef,
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acroForm,
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xfaData,
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// Use the same kind of XRef as the previous one.
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useXrefStream: isDict(xref.topDict, "XRef"),
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}).finally(() => {
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xref.resetNewTemporaryRef();
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});
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@ -18,12 +18,14 @@ import { Dict, isName, Name, Ref } from "./primitives.js";
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import {
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escapePDFName,
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escapeString,
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getSizeInBytes,
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numberToString,
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parseXFAPath,
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} from "./core_utils.js";
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import { SimpleDOMNode, SimpleXMLParser } from "./xml_parser.js";
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import { BaseStream } from "./base_stream.js";
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import { calculateMD5 } from "./crypto.js";
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import { Stream } from "./stream.js";
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async function writeObject(ref, obj, buffer, { encrypt = null }) {
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const transform = encrypt?.createCipherTransform(ref.num, ref.gen);
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@ -281,6 +283,112 @@ function updateXFA({ xfaData, xfaDatasetsRef, newRefs, xref }) {
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newRefs.push({ ref: xfaDatasetsRef, data });
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}
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async function getXRefTable(xrefInfo, baseOffset, newRefs, newXref, buffer) {
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buffer.push("xref\n");
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const indexes = getIndexes(newRefs);
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let indexesPosition = 0;
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for (const { ref, data } of newRefs) {
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if (ref.num === indexes[indexesPosition]) {
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buffer.push(
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`${indexes[indexesPosition]} ${indexes[indexesPosition + 1]}\n`
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);
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indexesPosition += 2;
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}
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// The EOL is \r\n to make sure that every entry is exactly 20 bytes long.
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// (see 7.5.4 - Cross-Reference Table).
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buffer.push(
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`${baseOffset.toString().padStart(10, "0")} ${Math.min(ref.gen, 0xffff).toString().padStart(5, "0")} n\r\n`
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);
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baseOffset += data.length;
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}
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computeIDs(baseOffset, xrefInfo, newXref);
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buffer.push("trailer\n");
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await writeDict(newXref, buffer);
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buffer.push("\nstartxref\n", baseOffset.toString(), "\n%%EOF\n");
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}
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function getIndexes(newRefs) {
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const indexes = [];
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for (const { ref } of newRefs) {
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if (ref.num === indexes.at(-2) + indexes.at(-1)) {
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indexes[indexes.length - 1] += 1;
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} else {
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indexes.push(ref.num, 1);
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}
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}
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return indexes;
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}
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async function getXRefStreamTable(
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xrefInfo,
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baseOffset,
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newRefs,
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newXref,
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buffer
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) {
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const xrefTableData = [];
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let maxOffset = 0;
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let maxGen = 0;
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for (const { ref, data } of newRefs) {
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maxOffset = Math.max(maxOffset, baseOffset);
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const gen = Math.min(ref.gen, 0xffff);
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maxGen = Math.max(maxGen, gen);
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xrefTableData.push([1, baseOffset, gen]);
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baseOffset += data.length;
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}
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newXref.set("Index", getIndexes(newRefs));
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const offsetSize = getSizeInBytes(maxOffset);
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const maxGenSize = getSizeInBytes(maxGen);
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const sizes = [1, offsetSize, maxGenSize];
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newXref.set("W", sizes);
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computeIDs(baseOffset, xrefInfo, newXref);
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const structSize = sizes.reduce((a, x) => a + x, 0);
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const data = new Uint8Array(structSize * xrefTableData.length);
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const stream = new Stream(data);
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stream.dict = newXref;
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let offset = 0;
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for (const [type, objOffset, gen] of xrefTableData) {
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offset = writeInt(type, sizes[0], offset, data);
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offset = writeInt(objOffset, sizes[1], offset, data);
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offset = writeInt(gen, sizes[2], offset, data);
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}
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await writeObject(xrefInfo.newRef, stream, buffer, {});
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buffer.push("startxref\n", baseOffset.toString(), "\n%%EOF\n");
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}
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function computeIDs(baseOffset, xrefInfo, newXref) {
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if (Array.isArray(xrefInfo.fileIds) && xrefInfo.fileIds.length > 0) {
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const md5 = computeMD5(baseOffset, xrefInfo);
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newXref.set("ID", [xrefInfo.fileIds[0], md5]);
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}
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}
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function getTrailerDict(xrefInfo, newRefs, useXrefStream) {
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const newXref = new Dict(null);
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newXref.set("Prev", xrefInfo.startXRef);
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const refForXrefTable = xrefInfo.newRef;
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if (useXrefStream) {
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newRefs.push({ ref: refForXrefTable, data: "" });
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newXref.set("Size", refForXrefTable.num + 1);
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newXref.set("Type", Name.get("XRef"));
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} else {
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newXref.set("Size", refForXrefTable.num);
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}
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if (xrefInfo.rootRef !== null) {
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newXref.set("Root", xrefInfo.rootRef);
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}
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if (xrefInfo.infoRef !== null) {
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newXref.set("Info", xrefInfo.infoRef);
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}
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if (xrefInfo.encryptRef !== null) {
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newXref.set("Encrypt", xrefInfo.encryptRef);
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}
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return newXref;
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}
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async function incrementalUpdate({
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originalData,
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xrefInfo,
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@ -293,6 +401,7 @@ async function incrementalUpdate({
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acroFormRef = null,
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acroForm = null,
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xfaData = null,
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useXrefStream = false,
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}) {
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await updateAcroform({
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xref,
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@ -314,9 +423,6 @@ async function incrementalUpdate({
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});
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}
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const newXref = new Dict(null);
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const refForXrefTable = xrefInfo.newRef;
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let buffer, baseOffset;
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const lastByte = originalData.at(-1);
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if (lastByte === /* \n */ 0x0a || lastByte === /* \r */ 0x0d) {
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@ -328,60 +434,23 @@ async function incrementalUpdate({
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baseOffset = originalData.length + 1;
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}
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newXref.set("Size", refForXrefTable.num + 1);
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newXref.set("Prev", xrefInfo.startXRef);
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newXref.set("Type", Name.get("XRef"));
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if (xrefInfo.rootRef !== null) {
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newXref.set("Root", xrefInfo.rootRef);
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}
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if (xrefInfo.infoRef !== null) {
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newXref.set("Info", xrefInfo.infoRef);
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}
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if (xrefInfo.encryptRef !== null) {
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newXref.set("Encrypt", xrefInfo.encryptRef);
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}
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// Add a ref for the new xref and sort them
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newRefs.push({ ref: refForXrefTable, data: "" });
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const newXref = getTrailerDict(xrefInfo, newRefs, useXrefStream);
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newRefs = newRefs.sort(
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(a, b) => /* compare the refs */ a.ref.num - b.ref.num
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);
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const xrefTableData = [[0, 1, 0xffff]];
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const indexes = [0, 1];
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let maxOffset = 0;
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for (const { ref, data } of newRefs) {
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maxOffset = Math.max(maxOffset, baseOffset);
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xrefTableData.push([1, baseOffset, Math.min(ref.gen, 0xffff)]);
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baseOffset += data.length;
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indexes.push(ref.num, 1);
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for (const { data } of newRefs) {
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buffer.push(data);
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}
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newXref.set("Index", indexes);
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await (useXrefStream
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? getXRefStreamTable(xrefInfo, baseOffset, newRefs, newXref, buffer)
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: getXRefTable(xrefInfo, baseOffset, newRefs, newXref, buffer));
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if (Array.isArray(xrefInfo.fileIds) && xrefInfo.fileIds.length > 0) {
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const md5 = computeMD5(baseOffset, xrefInfo);
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newXref.set("ID", [xrefInfo.fileIds[0], md5]);
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}
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const offsetSize = Math.ceil(Math.log2(maxOffset) / 8);
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const sizes = [1, offsetSize, 2];
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const structSize = sizes[0] + sizes[1] + sizes[2];
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const tableLength = structSize * xrefTableData.length;
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newXref.set("W", sizes);
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newXref.set("Length", tableLength);
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buffer.push(`${refForXrefTable.num} ${refForXrefTable.gen} obj\n`);
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await writeDict(newXref, buffer, null);
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buffer.push(" stream\n");
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const bufferLen = buffer.reduce((a, str) => a + str.length, 0);
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const footer = `\nendstream\nendobj\nstartxref\n${baseOffset}\n%%EOF\n`;
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const array = new Uint8Array(
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originalData.length + bufferLen + tableLength + footer.length
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const totalLength = buffer.reduce(
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(a, str) => a + str.length,
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originalData.length
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);
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const array = new Uint8Array(totalLength);
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// Original data
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array.set(originalData);
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@ -393,16 +462,6 @@ async function incrementalUpdate({
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offset += str.length;
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}
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// New xref table
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for (const [type, objOffset, gen] of xrefTableData) {
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offset = writeInt(type, sizes[0], offset, array);
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offset = writeInt(objOffset, sizes[1], offset, array);
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offset = writeInt(gen, sizes[2], offset, array);
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}
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// Add the footer
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writeString(footer, offset, array);
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return array;
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}
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@ -19,6 +19,7 @@ import {
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escapePDFName,
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escapeString,
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getInheritableProperty,
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getSizeInBytes,
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isAscii,
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isWhiteSpace,
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log2,
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@ -468,4 +469,21 @@ describe("core_utils", function () {
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);
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});
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});
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describe("getSizeInBytes", function () {
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it("should get the size in bytes to use to represent a positive integer", function () {
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expect(getSizeInBytes(0)).toEqual(0);
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for (let i = 1; i <= 0xff; i++) {
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expect(getSizeInBytes(i)).toEqual(1);
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}
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for (let i = 0x100; i <= 0xffff; i += 0x100) {
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expect(getSizeInBytes(i)).toEqual(2);
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}
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for (let i = 0x10000; i <= 0xffffff; i += 0x10000) {
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expect(getSizeInBytes(i)).toEqual(3);
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}
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});
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});
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});
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@ -37,26 +37,55 @@ describe("Writer", function () {
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info: {},
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};
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let data = await incrementalUpdate({ originalData, xrefInfo, newRefs });
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let data = await incrementalUpdate({
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originalData,
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xrefInfo,
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newRefs,
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useXrefStream: true,
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});
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data = bytesToString(data);
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const expected =
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let expected =
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"\nabc\n" +
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"defg\n" +
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"789 0 obj\n" +
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"<< /Size 790 /Prev 314 /Type /XRef /Index [0 1 123 1 456 1 789 1] " +
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"/ID [(id) (\x01#Eg\x89\xab\xcd\xef\xfe\xdc\xba\x98vT2\x10)] " +
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"/W [1 1 2] /Length 16>> stream\n" +
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"\x00\x01\xff\xff" +
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"\x01\x01\x00\x2d" +
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"\x01\x05\x00\x4e" +
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"\x01\x0a\x00\x00\n" +
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"<< /Prev 314 /Size 790 /Type /XRef /Index [123 1 456 1 789 1] " +
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"/W [1 1 1] /ID [(id) (\x01#Eg\x89\xab\xcd\xef\xfe\xdc\xba\x98vT2\x10)] " +
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"/Length 9>> stream\n" +
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"\x01\x01\x2d" +
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"\x01\x05\x4e" +
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"\x01\x0a\x00\n" +
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"endstream\n" +
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"endobj\n" +
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"startxref\n" +
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"10\n" +
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"%%EOF\n";
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expect(data).toEqual(expected);
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data = await incrementalUpdate({
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originalData,
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xrefInfo,
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newRefs,
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useXrefStream: false,
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});
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data = bytesToString(data);
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expected =
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"\nabc\n" +
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"defg\n" +
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"xref\n" +
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"123 1\n" +
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"0000000001 00045 n\r\n" +
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"456 1\n" +
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"0000000005 00078 n\r\n" +
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"789 1\n" +
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"0000000010 00000 n\r\n" +
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"trailer\n" +
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"<< /Prev 314 /Size 789 " +
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"/ID [(id) (\x01#Eg\x89\xab\xcd\xef\xfe\xdc\xba\x98vT2\x10)]>>\n" +
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"startxref\n" +
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"10\n" +
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"%%EOF\n";
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expect(data).toEqual(expected);
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});
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@ -74,17 +103,21 @@ describe("Writer", function () {
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info: {},
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};
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let data = await incrementalUpdate({ originalData, xrefInfo, newRefs });
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let data = await incrementalUpdate({
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originalData,
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xrefInfo,
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newRefs,
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useXrefStream: true,
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});
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data = bytesToString(data);
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const expected =
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"\nabc\n" +
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"789 0 obj\n" +
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"<< /Size 790 /Prev 314 /Type /XRef /Index [0 1 123 1 789 1] " +
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"/W [1 1 2] /Length 12>> stream\n" +
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"\x00\x01\xff\xff" +
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"\x01\x01\x00\x2d" +
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"\x01\x05\x00\x00\n" +
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"<< /Prev 314 /Size 790 /Type /XRef /Index [123 1 789 1] " +
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"/W [1 1 1] /Length 6>> stream\n" +
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"\x01\x01\x2d" +
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"\x01\x05\x00\n" +
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"endstream\n" +
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"endobj\n" +
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"startxref\n" +
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@ -187,6 +220,7 @@ describe("Writer", function () {
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acroForm,
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xfaData,
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xref: {},
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useXrefStream: true,
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});
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data = bytesToString(data);
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@ -202,8 +236,8 @@ describe("Writer", function () {
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"endstream\n" +
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"endobj\n" +
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"131415 0 obj\n" +
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"<< /Size 131416 /Prev 314 /Type /XRef /Index [0 1 789 1 101112 1 131415 1] /W [1 1 2] /Length 16>> stream\n" +
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"\u0000\u0001ÿÿ\u0001\u0001\u0000\u0000\u0001[\u0000\u0000\u0001¹\u0000\u0000\n" +
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"<< /Prev 314 /Size 131416 /Type /XRef /Index [789 1 101112 1 131415 1] /W [1 1 0] /Length 6>> stream\n" +
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"\x01\x01\x01[\x01¹\n" +
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"endstream\n" +
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"endobj\n" +
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"startxref\n" +
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