MDEV-6661 PI() does not work well in UCS2/UTF16/UTF32 context

MDEV-6666 Malformed result for CONCAT(utf8_column, binary_string)

Item_static_string_func::safe_charset_converter() and 
Item_hex_string::safe_charset_converter() did not
handle character sets with mbminlen>1 properly, as well as
did not handle conversion from binary to multi-byte well.

Introducing Item::const_charset_converter(), to reuse it in a number
of Item_*::safe_charset_converter().

1 files changed, 10 insertions, 0 deletions

diff --git a/sql/sql_string.h b/sql/sql_string.h
index 95c82518f9e..cc1db1d214b 100644
--- a/sql/sql_string.h
+++ b/sql/sql_string.h
@@ -351,6 +351,10 @@ public:
   bool set_or_copy_aligned(const char *s, uint32 arg_length, CHARSET_INFO *cs);
   bool copy(const char*s,uint32 arg_length, CHARSET_INFO *csfrom,
 	    CHARSET_INFO *csto, uint *errors);
+  bool copy(const String *str, CHARSET_INFO *tocs, uint *errors)
+  {
+    return copy(str->ptr(), str->length(), str->charset(), tocs, errors);
+  }
   void move(String &s)
   {
     free();
@@ -517,6 +521,12 @@ public:
   {
     return (s->alloced && Ptr >= s->Ptr && Ptr < s->Ptr + s->str_length);
   }
+  uint well_formed_length() const
+  {
+    int dummy_error;
+    return charset()->cset->well_formed_len(charset(), ptr(), ptr() + length(),
+                                            length(), &dummy_error);
+  }
   bool is_ascii() const
   {
     if (length() == 0)