From 700d7b442bf1c5d8bfafd985cb5306c3b053c52c Mon Sep 17 00:00:00 2001
From: jpirnay <jens@pirnay.com>
Date: Thu, 23 Apr 2026 09:39:58 +0200
Subject: [PATCH] fix: Erroneous navigation with long filenames in footnote
 links (#1723)

---
 lib/Epub/Epub/FootnoteEntry.h                  |  7 +++++--
 lib/Epub/Epub/Section.cpp                      |  2 +-
 .../Epub/parsers/ChapterHtmlSlimParser.cpp     | 18 +++++++++---------
 lib/Epub/Epub/parsers/ChapterHtmlSlimParser.h  |  3 +--
 4 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/lib/Epub/Epub/FootnoteEntry.h b/lib/Epub/Epub/FootnoteEntry.h
index 8023df42..6034a6a5 100644
--- a/lib/Epub/Epub/FootnoteEntry.h
+++ b/lib/Epub/Epub/FootnoteEntry.h
@@ -2,9 +2,12 @@
 
 #include <cstring>
 
+#define FOOTNOTE_NUMBER_LEN 32
+#define FOOTNOTE_HREF_LEN 96
+
 struct FootnoteEntry {
-  char number[24];
-  char href[64];
+  char number[FOOTNOTE_NUMBER_LEN];
+  char href[FOOTNOTE_HREF_LEN];
 
   FootnoteEntry() {
     number[0] = '\0';
diff --git a/lib/Epub/Epub/Section.cpp b/lib/Epub/Epub/Section.cpp
index 0bce47e2..8a157bce 100644
--- a/lib/Epub/Epub/Section.cpp
+++ b/lib/Epub/Epub/Section.cpp
@@ -12,7 +12,7 @@
 #include "parsers/ChapterHtmlSlimParser.h"
 
 namespace {
-constexpr uint8_t SECTION_FILE_VERSION = 21;
+constexpr uint8_t SECTION_FILE_VERSION = 22;
 constexpr uint32_t HEADER_SIZE = sizeof(uint8_t) +   // SECTION_FILE_VERSION
                                  sizeof(int) +       // fontId
                                  sizeof(float) +     // lineCompression
diff --git a/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp b/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp
index 8f520fae..4c92e398 100644
--- a/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp
+++ b/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp
@@ -742,9 +742,9 @@ void XMLCALL ChapterHtmlSlimParser::startElement(void* userData, const XML_Char*
       }
       self->insideFootnoteLink = true;
       self->footnoteLinkDepth = self->depth;
-      strncpy(self->currentFootnoteLinkHref, href, sizeof(self->currentFootnoteLinkHref) - 1);
-      self->currentFootnoteLinkHref[sizeof(self->currentFootnoteLinkHref) - 1] = '\0';
-      self->currentFootnoteLinkText[0] = '\0';
+      strncpy(self->currentFootnote.href, href, sizeof(self->currentFootnote.href) - 1);
+      self->currentFootnote.href[sizeof(self->currentFootnote.href) - 1] = '\0';
+      self->currentFootnote.number[0] = '\0';
       self->currentFootnoteLinkTextLen = 0;
 
       // Apply underline style to visually indicate the link
@@ -985,11 +985,11 @@ void XMLCALL ChapterHtmlSlimParser::characterData(void* userData, const XML_Char
     }
 
     // Extract footnote link text
-    for (int i = start; (self->currentFootnoteLinkTextLen < sizeof(self->currentFootnoteLinkText) - 1) && (i <= end);
+    for (int i = start; (self->currentFootnoteLinkTextLen < sizeof(self->currentFootnote.number) - 1) && (i <= end);
          ++i) {
-      self->currentFootnoteLinkText[self->currentFootnoteLinkTextLen++] = s[i];
+      self->currentFootnote.number[self->currentFootnoteLinkTextLen++] = s[i];
     }
-    self->currentFootnoteLinkText[self->currentFootnoteLinkTextLen] = '\0';
+    self->currentFootnote.number[self->currentFootnoteLinkTextLen] = '\0';
   }
 
   for (int i = 0; i < len; i++) {
@@ -1220,11 +1220,11 @@ void XMLCALL ChapterHtmlSlimParser::endElement(void* userData, const XML_Char* n
 
   // Closing a footnote link — create entry from collected text and href
   if (self->insideFootnoteLink && self->depth == self->footnoteLinkDepth) {
-    if (self->currentFootnoteLinkText[0] != '\0' && self->currentFootnoteLinkHref[0] != '\0') {
+    if (self->currentFootnote.number[0] != '\0' && self->currentFootnote.href[0] != '\0') {
       FootnoteEntry entry;
-      strncpy(entry.number, self->currentFootnoteLinkText, sizeof(entry.number) - 1);
+      strncpy(entry.number, self->currentFootnote.number, sizeof(entry.number) - 1);
       entry.number[sizeof(entry.number) - 1] = '\0';
-      strncpy(entry.href, self->currentFootnoteLinkHref, sizeof(entry.href) - 1);
+      strncpy(entry.href, self->currentFootnote.href, sizeof(entry.href) - 1);
       entry.href[sizeof(entry.href) - 1] = '\0';
       int wordIndex =
           self->wordsExtractedInBlock + (self->currentTextBlock ? static_cast<int>(self->currentTextBlock->size()) : 0);
diff --git a/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.h b/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.h
index 8d189f43..44605025 100644
--- a/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.h
+++ b/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.h
@@ -113,9 +113,8 @@ class ChapterHtmlSlimParser {
   // Footnote link tracking
   bool insideFootnoteLink = false;
   int footnoteLinkDepth = -1;
-  char currentFootnoteLinkText[24] = {};
+  FootnoteEntry currentFootnote = {};
   int currentFootnoteLinkTextLen = 0;
-  char currentFootnoteLinkHref[64] = {};
   std::vector<std::pair<int, FootnoteEntry>> pendingFootnotes;  // <wordIndex, entry>
   int wordsExtractedInBlock = 0;