From 8c565ece3eb0f3bb4fde4fa2d2dfc77899d6f23d Mon Sep 17 00:00:00 2001
From: Dorian Peron <peron@adacore.com>
Date: Fri, 4 Jul 2025 01:40:09 +0200
Subject: [PATCH] expr: add locale-aware length

---
 src/uu/expr/src/locale_aware.rs | 10 ++++++++++
 src/uu/expr/src/syntax_tree.rs  |  4 ++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/uu/expr/src/locale_aware.rs b/src/uu/expr/src/locale_aware.rs
index ebdc78e0c..cc07f9cc6 100644
--- a/src/uu/expr/src/locale_aware.rs
+++ b/src/uu/expr/src/locale_aware.rs
@@ -58,3 +58,13 @@ fn index_with_locale(
 pub(crate) fn locale_aware_index(left: &MaybeNonUtf8Str, right: &MaybeNonUtf8Str) -> usize {
     index_with_locale(left, right, get_locale_encoding())
 }
+
+/// Perform a string length calculation depending on the current locale. In
+/// UTF-8 locale, it will count valid UTF-8 chars, and fallback to counting
+/// bytes otherwise. In Non UTF-8 locale, directly return input byte length.
+pub(crate) fn locale_aware_length(input: &MaybeNonUtf8Str) -> usize {
+    match get_locale_encoding() {
+        UEncoding::Utf8 => std::str::from_utf8(input).map_or(input.len(), |s| s.chars().count()),
+        UEncoding::Ascii => input.len(),
+    }
+}
diff --git a/src/uu/expr/src/syntax_tree.rs b/src/uu/expr/src/syntax_tree.rs
index 66e75044d..8a45c2362 100644
--- a/src/uu/expr/src/syntax_tree.rs
+++ b/src/uu/expr/src/syntax_tree.rs
@@ -13,7 +13,7 @@ use onig::{Regex, RegexOptions, Syntax};
 
 use crate::{
     ExprError, ExprResult,
-    locale_aware::{locale_aware_index, locale_comparison},
+    locale_aware::{locale_aware_index, locale_aware_length, locale_comparison},
 };
 
 pub(crate) type MaybeNonUtf8String = Vec<u8>;
@@ -583,7 +583,7 @@ impl AstNode {
                         continue;
                     };
 
-                    let length = string?.eval_as_string().iter().count();
+                    let length = locale_aware_length(&string?.eval_as_string());
                     result_stack.insert(node.id, Ok(length.into()));
                 }
             }