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fix(ignore): harden final .html4ignore open against symlink traversal #623

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fix(ignore): harden final .html4ignore open against symlink traversal #623

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4 changes: 4 additions & 0 deletions .jules/sentinel.md
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Expand Up @@ -99,3 +99,7 @@
**Root cause:** The protected implementation added canonical names to the exclusion set but did not compare each observed directory entry through a locale-stable normalized key.
**Prevention:** Build one `Locale.ROOT` lowercase set from the canonical sensitive names, compare every observed name against it, and add the original spelling to the exclusion set so downstream exact membership remains correct.
**Evidence:** `testProcessIgnoreFileTreatsSensitiveNamesCaseInsensitively` failed on test-only commit `472b916cd40f70693c4e1eb48956042a25353feb` (CI run `31469596932`) and passed with the source fix at `bb113d858ccfc42ddaecf6729749b238e5ade2d0` (CI run `31469921661`).
## 2026-09-04 - Prevent TOCTOU in file reading
**Vulnerability:** `File.useLines` implicitly resolves symbolic links internally, which can lead to Time-of-Check-to-Time-of-Use (TOCTOU) if the file is replaced by a symlink after validation.
**Learning:** Even if symlinks are verified as absent prior to reading, Kotlin's standard library file readers might still traverse them during the reading phase, opening a TOCTOU window.
**Prevention:** Replace `File.useLines` with `Files.newInputStream(..., StandardOpenOption.READ, LinkOption.NOFOLLOW_LINKS).bufferedReader().useLines` to strictly disallow symlink traversal when opening the file.
2 changes: 1 addition & 1 deletion src/main/kotlin/html4tree/main.kt
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Expand Up @@ -309,7 +309,7 @@ fun process_ignore_file(curr_dir: File, dirFilesNames: Array<String>? = null): S
if(ignore_file.isFile && !Files.isSymbolicLink(ignore_file.toPath()) && ignore_file.canRead() && ignore_file.length() <= 1048576){
val ignored_matchers = mutableListOf<java.nio.file.PathMatcher>()

ignore_file.useLines { lines ->
java.nio.file.Files.newInputStream(ignore_file.toPath(), java.nio.file.StandardOpenOption.READ, java.nio.file.LinkOption.NOFOLLOW_LINKS).bufferedReader().useLines { lines ->
for ((lineIndex, it) in lines.withIndex()) {
// 줄 수 제한이 패턴 수도 함께 상한(줄당 최대 1개 패턴)하므로 별도 패턴 카운터는 불필요
if (lineIndex >= 1000) break
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