mirrors/pdf.js
1
0
Fork 0
mirror of https://github.com/mozilla/pdf.js.git synced 2025-04-25 17:48:07 +02:00
Code Activity

Support parsing encrypted documents in XRef.indexObjects (issue 15893)

Browse source 
*Please note:* The reduced test-case is *not* a perfect reproduction of the original PDF document, since this one fails to open in e.g. Adobe Reader, but I do believe that it captures the most important points here.

For corrupt *and* encrypted PDF documents, it's possible that only some trailer dictionaries actually contain an /Encrypt-entry. Previously we'd could easily miss that, since we generally pick the first not obviously corrupt trailer dictionary, and the solution implemented here is to simply pre-parse all trailer dictionaries to see if there's any /Encrypt-entries.
This commit is contained in:
Jonas Jenwald 2023-01-06 10:27:20 +01:00
parent e36564668b
commit 7d94fdeb48
4 changed files with 35 additions and 11 deletions
Download patch file Download diff file Expand all files Collapse all files

38
src/core/xref.js
View file

@ -581,16 +581,11 @@ class XRef {
this.startXRefQueue.push(xrefStm);
this.readXRef(/* recoveryMode */ true);
}
// finding main trailer
let trailerDict, trailerError;
for (const trailer of [...trailers, "generationFallback", ...trailers]) {
if (trailer === "generationFallback") {
if (!trailerError) {
break; // No need to fallback if there were no validation errors.
}
this._generationFallback = true;
continue;
}
const trailerDicts = [];
// Pre-parsing the trailers to check if the document is possibly encrypted.
let isEncrypted = false;
for (const trailer of trailers) {
stream.pos = trailer;
const parser = new Parser({
lexer: new Lexer(stream),
@ -607,6 +602,23 @@ class XRef {
if (!(dict instanceof Dict)) {
continue;
}
trailerDicts.push(dict);
if (dict.has("Encrypt")) {
isEncrypted = true;
}
}
// finding main trailer
let trailerDict, trailerError;
for (const dict of [...trailerDicts, "genFallback", ...trailerDicts]) {
if (dict === "genFallback") {
if (!trailerError) {
break; // No need to fallback if there were no validation errors.
}
this._generationFallback = true;
continue;
}
// Do some basic validation of the trailer/root dictionary candidate.
let validPagesDict = false;
try {
@ -628,7 +640,11 @@ class XRef {
continue;
}
// taking the first one with 'ID'
if (validPagesDict && dict.has("ID")) {
if (
validPagesDict &&
(!isEncrypted || dict.has("Encrypt")) &&
dict.has("ID")
) {
return dict;
}
// The current dictionary is a candidate, but continue searching.