Bug#52520 Difference in tinytext utf column metadata

      Problems:
      - regression (compating to version 5.1) in metadata for BLOB types
      - inconsistency between length metadata in server and embedded for BLOB types
      - wrong max_length calculation in items derived from BLOB columns
     @ libmysqld/lib_sql.cc
        Calculating length metadata in embedded similary to server version,
        using new function char_to_byte_length_safe().
     @ mysql-test/r/ctype_utf16.result
        Adding tests
     @ mysql-test/r/ctype_utf32.result
        Adding tests
     @ mysql-test/r/ctype_utf8.result
        Adding tests
     @ mysql-test/r/ctype_utf8mb4.result
        Adding tests
     @ mysql-test/t/ctype_utf16.test
        Adding tests
     @ mysql-test/t/ctype_utf32.test
        Adding tests
     @ mysql-test/t/ctype_utf8.test
        Adding tests
     @ mysql-test/t/ctype_utf8mb4.test
        Adding tests
     @ sql/field.cc
        Overriding char_length() for Field_blob:
        unlike in generic Item::char_length() we don't
        divide to mbmaxlen for BLOBs.
     @ sql/field.h
        - Making Field::char_length() virtual
        - Adding prototype for Field_blob::char_length()
     @ sql/item.h
        - Adding new helper function char_to_byte_length_safe()
        - Using new function
     @ sql/protocol.cc
        Using new function char_to_byte_length_safe().

    modified:
      libmysqld/lib_sql.cc
      mysql-test/r/ctype_utf16.result
      mysql-test/r/ctype_utf32.result
      mysql-test/r/ctype_utf8.result
      mysql-test/r/ctype_utf8mb4.result
      mysql-test/t/ctype_utf16.test
      mysql-test/t/ctype_utf32.test
      mysql-test/t/ctype_utf8.test
      mysql-test/t/ctype_utf8mb4.test
      sql/field.cc
      sql/field.h
      sql/item.h
      sql/protocol.cc

1 files changed, 3 insertions, 5 deletions

diff --git a/sql/protocol.cc b/sql/protocol.cc
index eeb248012ab..ac78ac88ec6 100644
--- a/sql/protocol.cc
+++ b/sql/protocol.cc
@@ -747,8 +747,7 @@ bool Protocol::send_result_set_metadata(List<Item> *list, uint flags)
       else
       {
         /* With conversion */
-        ulonglong max_length;
-        uint32 field_length;
+        uint32 field_length, max_length;
         int2store(pos, thd_charset->number);
         /*
           For TEXT/BLOB columns, field_length describes the maximum data
@@ -771,9 +770,8 @@ bool Protocol::send_result_set_metadata(List<Item> *list, uint flags)
                      field.type <= MYSQL_TYPE_BLOB) ?
                      field.length / item->collation.collation->mbminlen :
                      field.length / item->collation.collation->mbmaxlen;
-        max_length*= thd_charset->mbmaxlen;
-        field_length= (max_length > UINT_MAX32) ? 
-          UINT_MAX32 : (uint32) max_length;
+        field_length= char_to_byte_length_safe(max_length,
+                                               thd_charset->mbmaxlen);
         int4store(pos + 2, field_length);
       }
       pos[6]= field.type;