From 5e95240b6e40d3574b51b597051662a157c0b7d8 Mon Sep 17 00:00:00 2001
From: Wojtek Kosior <koszko@koszko.org>
Date: Wed, 24 Jan 2024 21:38:49 +0100
Subject: Forbid `.` and `..` in loaded resource file paths.

---
 src/guile/cantius.scm | 12 ++++++++++++
 1 file changed, 12 insertions(+)

(limited to 'src')

diff --git a/src/guile/cantius.scm b/src/guile/cantius.scm
index fe8131a..af37a32 100644
--- a/src/guile/cantius.scm
+++ b/src/guile/cantius.scm
@@ -24,8 +24,20 @@
 
 
 
+(define %illegal-path-regex
+  ;; Forbid `.` and `..` segments in paths.
+  (make-regexp "^(.*/)?[.][.]?(/.*)?$"))
+
+(define legal-path?
+  (negate (cut regexp-exec %illegal-path-regex <>)))
+
 (export find-resource-file)
 (define* (find-resource-file file #:optional (root-path (%resource-root-path)))
+  (unless (legal-path? file)
+    (raise (condition
+            (&error)
+            (&message (message (format #f "Illegal path ~a" file))))))
+
   (let loop ((paths root-path))
     (match paths
       (()
-- 
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