From 13da7cc4a79ecc191939227ced096ebb6b6048fc Mon Sep 17 00:00:00 2001
From: weili <541602953@qq.com>
Date: Fri, 12 Jun 2026 04:51:15 +0000
Subject: [PATCH] find: -printf: advance past a full char in advance_one to
 avoid a panic
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advance_one read a full `char` via front() but then dropped it by slicing one
byte (`&self.string[1..]`). When that char is multibyte (e.g. a `€` after a `%`
conversion, a `\` escape, or a `%A`/`%C`/`%T` time directive), byte index 1 is
not a char boundary and the slice panics. Advance by the char's UTF-8 length so
multibyte input routes through the normal handling instead of aborting.
---
 src/find/matchers/printf.rs | 12 +++++++++++-
 tests/test_find.rs          | 16 ++++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/src/find/matchers/printf.rs b/src/find/matchers/printf.rs
index 038ec7fb..906e1594 100644
--- a/src/find/matchers/printf.rs
+++ b/src/find/matchers/printf.rs
@@ -149,7 +149,7 @@ impl FormatStringParser<'_> {
 
     fn advance_one(&mut self) -> Result<char, Box<dyn Error>> {
         let c = self.front()?;
-        self.string = &self.string[1..];
+        self.string = &self.string[c.len_utf8()..];
         Ok(c)
     }
 
@@ -719,6 +719,16 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_parse_multibyte_char_after_directive() {
+        assert_eq!(
+            FormatString::parse("%€").unwrap().components,
+            vec![FormatComponent::Literal("€".to_owned())]
+        );
+        assert!(FormatString::parse("\\€").is_err());
+        assert!(FormatString::parse("%A€").is_err());
+    }
+
     #[test]
     fn test_parse_formatting() {
         fn unaligned_directive(directive: FormatDirective) -> FormatComponent {
diff --git a/tests/test_find.rs b/tests/test_find.rs
index cfee583f..997c0bfe 100644
--- a/tests/test_find.rs
+++ b/tests/test_find.rs
@@ -519,6 +519,22 @@ fn find_printf_octal_escape_before_multibyte_char() {
         .stdout_only("\0€\n");
 }
 
+#[test]
+fn find_printf_multibyte_char_after_directive() {
+    ucmd()
+        .args(&["./test_data/simple", "-maxdepth", "0", "-printf", "%€\\n"])
+        .succeeds()
+        .stdout_only("€\n");
+    ucmd()
+        .args(&["./test_data/simple", "-maxdepth", "0", "-printf", "\\€\\n"])
+        .fails()
+        .stderr_contains("find: Invalid escape sequence");
+    ucmd()
+        .args(&["./test_data/simple", "-maxdepth", "0", "-printf", "%A€"])
+        .fails()
+        .stderr_contains("find: Invalid time specifier");
+}
+
 #[cfg(unix)]
 #[test]
 fn find_perm() {