From 428c6ed4a5cb48f24fa5dd1ee4376722491f8f82 Mon Sep 17 00:00:00 2001
From: Ray Miller <ray@1729.org.uk>
Date: Sat, 4 Jan 2025 12:13:40 +0000
Subject: [PATCH] Shell quote zero-length strings.

---
 modules/ordo/util/shell-quote.scm | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/modules/ordo/util/shell-quote.scm b/modules/ordo/util/shell-quote.scm
index 6333264..84268e7 100644
--- a/modules/ordo/util/shell-quote.scm
+++ b/modules/ordo/util/shell-quote.scm
@@ -27,15 +27,16 @@
 (define (needs-escape? s)
   (irregex-search unsafe-characters s))
 
+(define (squash-quotes m)
+  (let ((n (/ (- (irregex-match-end-index m)
+                 (irregex-match-start-index m))
+              4)))
+    (list->string (append
+                   '(#\' #\")
+                   (make-list n #\')
+                   '(#\" #\')))))
+
 (define (escape s)
-  (define (squash-quotes m)
-    (let ((n (/ (- (irregex-match-end-index m)
-                   (irregex-match-start-index m))
-                4)))
-      (list->string (append
-                     '(#\' #\")
-                     (make-list n #\')
-                     '(#\" #\')))))
   (chain s
          ;; ' -> '\''
          (irregex-replace/all (irregex "'") _ "'\\''")
@@ -50,4 +51,7 @@
 
 (define (shell-quote-string s)
   "Quote strings for passing through the shell"
-  (if (needs-escape? s) (escape s) s))
+  (cond
+   ((zero? (string-length s)) "''")
+   ((needs-escape? s) (escape s))
+   (else s)))