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Merge pull request #21699 from calixteman/fix/pdf-editor-field-parent-cycle

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Avoid an infinite loop on cyclic field Parent chains
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Tim van der Meij 2026-08-04 20:58:25 +02:00 committed by GitHub
commit 8e3a1fd4ad
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2 changed files with 77 additions and 1 deletions
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17
src/core/editor/pdf_editor.js
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@ -2147,8 +2147,20 @@ class PDFEditor {
}
let parent = parentRef;
let lastNonNullParent = parentRef;
const visited = new RefSet();
while (true) {
parent = xref.fetchIfRef(parent)?.getRaw("Parent") || null;
if (parent instanceof Ref) {
if (visited.has(parent)) {
// Cyclic Parent chain: stop on the field closing the cycle.
break;
}
visited.put(parent);
}
const parentDict = xref.fetchIfRef(parent);
if (!(parentDict instanceof Dict)) {
break;
}
parent = parentDict.getRaw("Parent") || null;
if (!parent) {
break;
}
@ -2221,6 +2233,9 @@ class PDFEditor {
}
processed.put(oldKidRef);
const kid = xref.fetchIfRef(oldKidRef);
if (!(kid instanceof Dict)) {
continue;
}
if (kid.has("Kids")) {
const kidsArray = kid.get("Kids");
if (!Array.isArray(kidsArray)) {

61
test/unit/api_spec.js
View File

@ -7775,6 +7775,67 @@ small scripts as well as for`);
await loadingTask.destroy();
});
it("rebuilds a missing AcroForm Fields array with a Parent cycle", async function () {
const data = assemblePdf([
"1 0 obj\n<< /Type /Catalog /Pages 2 0 R /AcroForm 6 0 R >>\nendobj\n",
"2 0 obj\n<< /Type /Pages /Kids [3 0 R] /Count 1 >>\nendobj\n",
"3 0 obj\n<< /Type /Page /Parent 2 0 R /MediaBox [0 0 100 100] " +
"/Annots [4 0 R] >>\nendobj\n",
"4 0 obj\n<< /Type /Annot /Subtype /Widget /Rect [0 0 20 10] " +
"/Parent 5 0 R >>\nendobj\n",
// The Parent chain 5 -> 7 -> 5 is cyclic.
"5 0 obj\n<< /FT /Tx /T (group) /Kids [4 0 R] /Parent 7 0 R >>\n" +
"endobj\n",
"6 0 obj\n<< /DA (/Helv 10 Tf) >>\nendobj\n",
"7 0 obj\n<< /T (cycle) /Kids [5 0 R] /Parent 5 0 R >>\nendobj\n",
]);
let loadingTask = getDocument({ data });
let pdfDoc = await loadingTask.promise;
const extracted = await pdfDoc.extractPages([{ document: null }]);
expect(extracted).not.toBeNull();
await loadingTask.destroy();
loadingTask = getDocument({ data: extracted });
pdfDoc = await loadingTask.promise;
const fieldObjects = await pdfDoc.getFieldObjects();
expect([...fieldObjects.keys()]).toEqual(["group"]);
const annotations = await (await pdfDoc.getPage(1)).getAnnotations();
expect(annotations[0].fieldName).toEqual("group");
await loadingTask.destroy();
});
it("rebuilds a missing AcroForm Fields array with a bogus Parent", async function () {
const data = assemblePdf([
"1 0 obj\n<< /Type /Catalog /Pages 2 0 R /AcroForm 6 0 R >>\nendobj\n",
"2 0 obj\n<< /Type /Pages /Kids [3 0 R] /Count 1 >>\nendobj\n",
"3 0 obj\n<< /Type /Page /Parent 2 0 R /MediaBox [0 0 100 100] " +
"/Annots [4 0 R] >>\nendobj\n",
"4 0 obj\n<< /Type /Annot /Subtype /Widget /Rect [0 0 20 10] " +
"/FT /Tx /T (widget) /Parent 5 0 R >>\nendobj\n",
// The Parent isn't a dictionary.
"5 0 obj\n[1 2 3]\nendobj\n",
"6 0 obj\n<< /DA (/Helv 10 Tf) >>\nendobj\n",
]);
let loadingTask = getDocument({ data });
let pdfDoc = await loadingTask.promise;
const extracted = await pdfDoc.extractPages([{ document: null }]);
expect(extracted).not.toBeNull();
await loadingTask.destroy();
loadingTask = getDocument({ data: extracted });
pdfDoc = await loadingTask.promise;
const annotations = await (await pdfDoc.getPage(1)).getAnnotations();
expect(annotations.length).toEqual(1);
expect(annotations[0].fieldName).toEqual("widget");
await loadingTask.destroy();
});
it("preserves indirect AcroForm default resources", async function () {
const pdfData = assemblePdf([
"1 0 obj\n<< /Type /Catalog /Pages 2 0 R " +