FB2: Maximum call stack size exceeded

[pok49]

I've installed Foliate and tried some ebooks. Some of them opened as expected, but quite a few failed with the error message screen:

:-(
Could not open file
Maximum call stack size exceeded.
[Open Another File]

A small fb2 book of this sort is available here.

I've reduced it to a smaller test (1214 bytes; I'll try to attach it). The problem seems to be due to hyperlinks in the text.

I am not alone in experiencing this problem; there are similar complaints in the Net, e.g. in this post:

Ответ на: комментарий от AP 07.04.22 23:18:41
Спасибо за наводку. Выглядит симпатично, правда некоторые fb2 книги не открывает, валится с «Maximum call stack size exceeded». Кто-нибудь сталкивался с таким?

My testing environment:
% uname -a
Linux Eee901 4.9.0-279-antix.1-486-smp #1 SMP Sun Aug 8 20:59:37 EEST 2021 i686 GNU/Linux
%
% dpkg-query -l 'foliate'
||/ Name Version Architecture Description
+++-===============================-============-============-================>
ii com.github.johnfactotum.foliate 2.6.4 all Simple and modern
fail17.fb2.zip

[johnfactotum]

Thanks for reporting this. It's indeed caused by hyperlinks. The smaller test case only test for links within a section, but the larger one seems to contain also links to other sections which then links back to the original section. So I think one needs to keep track of all the sections that one has traversed before to prevent infinite recursion. Here's a quick fix I came up with:

diff --git a/src/web/webpub.js b/src/web/webpub.js
index 5479c16..36cd89b 100644
--- a/src/web/webpub.js
+++ b/src/web/webpub.js
@@ -156,7 +156,8 @@ const webpubFromFB2 = async (uri, filename) => {
 
 const fb2Sections = new Map()
 
-const fb2ToHtml = (fb2, node, itemFromElement, isSection) => {
+const fb2ToHtml = (fb2, node, itemFromElement, isSection, parents = []) => {
+    parents.push(node)
     const walk = (fb2, node, f) => {
         const [output, childF, post = x => x] = f(fb2, node)
         node = node.firstChild
@@ -229,9 +230,8 @@ const fb2ToHtml = (fb2, node, itemFromElement, isSection) => {
                     let note = fb2.getElementById(id)
                     if (!note) return [el]
                     while (!note.matches('body > *')) note = note.parentElement
-                    let item = fb2Sections.get(note)
-                    if (!item && itemFromElement) item = itemFromElement(note)
-                    if (item) el.setAttribute('href', item.href + '#' + id)
+                    const item = itemFromElement ? itemFromElement(note, parents) : null
+                    if (item) el.setAttribute('href', (item?.href ?? '') + '#' + id)
                 }
                 return [el]
             }
@@ -488,9 +488,10 @@ const processFB2 = async (fb2, blob, filename) => {
     const styleUrl = URL.createObjectURL(styleBlob)
 
     let i = 0
-    const itemFromElement = x => {
+    const itemFromElement = (x, parents = []) => {
+        if (parents.includes(x)) return
         if (fb2Sections.has(x)) return fb2Sections.get(x)
-        const section = fb2ToHtml(fb2, x, itemFromElement)
+        const section = fb2ToHtml(fb2, x, itemFromElement, false, parents)
 
         const titles = [
             ...section.querySelectorAll(':scope > section > header') || []]
@@ -540,7 +541,7 @@ const processFB2 = async (fb2, blob, filename) => {
     const toc = []
     bodies.forEach((body, i) => {
         const name = body.getAttribute('name')
-        const sections = [...body.children].map(itemFromElement)
+        const sections = [...body.children].map(x => itemFromElement(x))
         readingOrder.push(...sections)
 
         const titledSections = sections.filter(x => x.title)

Would be great if you could test and see if it fixes the issue and if it causes any regressions. (I guess I should really set up some tests when I have time.)

[johnfactotum]

Fixed in the gtk4 branch. With the new renderer (#962), there's no need to pre-generate blobs for every section, as a result there's no need for recursive loading linked sections anymore.