From ceedd4195f8d5b3084f7b494ca0ab7965634246d Mon Sep 17 00:00:00 2001
From: xiangjinwu <17769960+xiangjinwu@users.noreply.github.com>
Date: Tue, 2 Jan 2024 13:07:40 +0800
Subject: [PATCH] fix(pgwire): `TruncatedFmt` should respect utf8 char boundary
 (#14292)

---
 src/utils/pgwire/src/lib.rs         |  1 +
 src/utils/pgwire/src/pg_protocol.rs | 18 ++++++++++++++++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/utils/pgwire/src/lib.rs b/src/utils/pgwire/src/lib.rs
index d4018373db005..96d439b8b94ff 100644
--- a/src/utils/pgwire/src/lib.rs
+++ b/src/utils/pgwire/src/lib.rs
@@ -18,6 +18,7 @@
 #![feature(trusted_len)]
 #![feature(lazy_cell)]
 #![feature(buf_read_has_data_left)]
+#![feature(round_char_boundary)]
 #![expect(clippy::doc_markdown, reason = "FIXME: later")]
 
 pub mod error;
diff --git a/src/utils/pgwire/src/pg_protocol.rs b/src/utils/pgwire/src/pg_protocol.rs
index 98ad88ffcce25..ebffb24d81118 100644
--- a/src/utils/pgwire/src/pg_protocol.rs
+++ b/src/utils/pgwire/src/pg_protocol.rs
@@ -1139,8 +1139,9 @@ pub mod truncated_fmt {
             }
 
             if self.remaining < s.len() {
-                self.f.write_str(&s[0..self.remaining])?;
-                self.remaining = 0;
+                let actual = s.floor_char_boundary(self.remaining);
+                self.f.write_str(&s[0..actual])?;
+                self.remaining -= actual;
                 self.f.write_str("...(truncated)")?;
                 self.finished = true; // so that ...(truncated) is printed exactly once
             } else {
@@ -1180,4 +1181,17 @@ pub mod truncated_fmt {
             .write_fmt(format_args!("{}", self.0))
         }
     }
+
+    #[cfg(test)]
+    mod tests {
+        use super::*;
+
+        #[test]
+        fn test_trunc_utf8() {
+            assert_eq!(
+                format!("{}", TruncatedFmt(&"select '🌊';", 10)),
+                "select '...(truncated)",
+            );
+        }
+    }
 }