From 0cb64bbd56e7228409f1b527881bfc164327d4cb Mon Sep 17 00:00:00 2001
From: weili <541602953@qq.com>
Date: Wed, 5 Aug 2026 06:29:45 +0000
Subject: [PATCH] stat: truncate string precision on a byte boundary to avoid a
 panic

print_str applied a `%.P` precision by slicing the &str value (`&s[..p]`),
which panics when p lands inside a multibyte UTF-8 character (e.g. a file
name printed with %n). Route it through write_padded_bytes, as print_os_str
already does, so truncation and padding operate on bytes and match GNU
stat's byte truncation instead of crashing.
---
 src/uu/stat/src/stat.rs    | 13 ++++++++-----
 tests/by-util/test_stat.rs | 11 +++++++++++
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/src/uu/stat/src/stat.rs b/src/uu/stat/src/stat.rs
index 8e1f76779a1..2cc6c655701 100644
--- a/src/uu/stat/src/stat.rs
+++ b/src/uu/stat/src/stat.rs
@@ -405,11 +405,14 @@ fn determine_padding_char(flags: Flags) -> Padding {
 /// * `width` - The width of the field for the printed string.
 /// * `precision` - How many digits of precision, if any.
 fn print_str(s: &str, flags: Flags, width: usize, precision: Precision) {
-    let s = match precision {
-        Precision::Number(p) if p < s.len() => &s[..p],
-        _ => s,
-    };
-    pad_and_print(s, flags.left, width, Padding::Space);
+    // Truncate and pad on the byte representation, so a precision that lands inside a multibyte character does not cause a panic.
+    let _ = write_padded_bytes(
+        std::io::stdout(),
+        s.as_bytes(),
+        flags.left,
+        width,
+        precision,
+    );
 }
 
 /// Prints a `OsString` value based on the provided flags, width, and precision.
diff --git a/tests/by-util/test_stat.rs b/tests/by-util/test_stat.rs
index 153ef39c88d..13103ecc772 100644
--- a/tests/by-util/test_stat.rs
+++ b/tests/by-util/test_stat.rs
@@ -593,6 +593,17 @@ fn test_invalid_directive_after_multibyte_char() {
     }
 }
 
+#[test]
+fn test_precision_splits_multibyte_char_in_value() {
+    let ts = TestScenario::new(util_name!());
+    let at = &ts.fixtures;
+    at.touch("é");
+    ts.ucmd()
+        .args(&["-c", "%.1n", "é"])
+        .succeeds()
+        .stdout_only_bytes([0xc3, b'\n']);
+}
+
 #[test]
 #[cfg(all(
     feature = "feat_selinux",