MDEV-6752 Trailing incomplete characters are not replaced to question marks on conversion

1 files changed, 9 insertions, 2 deletions

diff --git a/sql/sql_string.cc b/sql/sql_string.cc
index 55bf0f9b1c7..a7bfa6c1455 100644
--- a/sql/sql_string.cc
+++ b/sql/sql_string.cc
@@ -1022,8 +1022,15 @@ well_formed_copy_nchars(CHARSET_INFO *to_cs,
         wc= '?';
       }
       else
-        break;  // Not enough characters
-
+      {
+        if ((uchar *) from >= from_end)
+          break; // End of line
+        // Incomplete byte sequence
+        if (!*well_formed_error_pos)
+          *well_formed_error_pos= from;
+        from++;
+        wc= '?';
+      }
 outp:
       if ((cnvres= (*wc_mb)(to_cs, wc, (uchar*) to, to_end)) > 0)
         to+= cnvres;