Added ErrConvString.lex_cstring() to simplify code

This allows us to use String::append() without using strlen().

The changes to the ErrConvString class where done by Alexander Barkov

sql/item.cc

@@ -3816,7 +3816,7 @@ void Item_string::print(String *str, enum_query_type query_type)
         changed.
       */
       ErrConvString tmp(str_value.ptr(), str_value.length(), &my_charset_bin);
-      str->append(tmp.ptr());
+      str->append(tmp.lex_cstring());
     }
     else
     {

sql/key.cc

@@ -393,7 +393,7 @@ void field_unpack(String *to, Field *field, const uchar *rec, uint max_length,
     if (max_length < field->pack_length())
       tmp.length(MY_MIN(tmp.length(),max_length));
     ErrConvString err(&tmp);
-    to->append(err.ptr());
+    to->append(err.lex_cstring());
   }
   else
     to->append(STRING_WITH_LEN("???"));

sql/sql_class.h

@@ -7558,10 +7558,10 @@ class ErrConvDQName: public ErrConv
   ErrConvDQName(const Database_qualified_name *name)
    :m_name(name)
   { }
-  const char *ptr() const
+  LEX_CSTRING lex_cstring() const override
   {
-    m_name->make_qname(err_buffer, sizeof(err_buffer));
-    return err_buffer;
+    size_t length= m_name->make_qname(err_buffer, sizeof(err_buffer));
+    return {err_buffer, length};
   }
 };
 

sql/sql_error.cc

@@ -864,10 +864,10 @@ extern "C" int my_wc_mb_utf8_null_terminated(CHARSET_INFO *cs,
    @param from_cs     charset from convert
  
    @retval
-   result string
+   result string length
 */
 
-char *err_conv(char *buff, uint to_length, const char *from,
+size_t err_conv(char *buff, uint to_length, const char *from,
                 uint from_length, CHARSET_INFO *from_cs)
 {
   char *to= buff;
@@ -919,7 +919,7 @@ char *err_conv(char *buff, uint to_length, const char *from,
                                &errors);
     to[res]= 0;
   }
-  return buff;
+  return res;
 }
 
 

sql/sql_error.h

@@ -811,7 +811,7 @@ class Warning_info
 };
 
 
-extern char *err_conv(char *buff, uint to_length, const char *from,
+extern size_t err_conv(char *buff, uint to_length, const char *from,
                        uint from_length, CHARSET_INFO *from_cs);
 
 class ErrBuff
@@ -824,31 +824,37 @@ class ErrBuff
     err_buffer[0]= '\0';
   }
   const char *ptr() const { return err_buffer; }
-  const char *set_longlong(const Longlong_hybrid &nr) const
+  LEX_CSTRING set_longlong(const Longlong_hybrid &nr) const
   {
-    return nr.is_unsigned() ? ullstr(nr.value(), err_buffer) :
-                              llstr(nr.value(), err_buffer);
+    int radix= nr.is_unsigned() ? 10 : -10;
+    const char *end= longlong10_to_str(nr.value(), err_buffer, radix);
+    DBUG_ASSERT(end >= err_buffer);
+    return {err_buffer, (size_t) (end - err_buffer)};
   }
-  const char *set_double(double nr) const
+  LEX_CSTRING set_double(double nr) const
   {
-    my_gcvt(nr, MY_GCVT_ARG_DOUBLE, sizeof(err_buffer), err_buffer, 0);
-    return err_buffer;
+    size_t length= my_gcvt(nr, MY_GCVT_ARG_DOUBLE,
+                           sizeof(err_buffer), err_buffer, 0);
+    return {err_buffer, length};
   }
-  const char *set_decimal(const decimal_t *d) const
+  LEX_CSTRING set_decimal(const decimal_t *d) const
   {
-    int len= sizeof(err_buffer);
-    decimal2string(d, err_buffer, &len, 0, 0, ' ');
-    return err_buffer;
+    int length= sizeof(err_buffer);
+    decimal2string(d, err_buffer, &length, 0, 0, ' ');
+    DBUG_ASSERT(length >= 0);
+    return {err_buffer, (size_t) length};
   }
-  const char *set_str(const char *str, size_t len, CHARSET_INFO *cs) const
+  LEX_CSTRING set_str(const char *str, size_t len, CHARSET_INFO *cs) const
   {
     DBUG_ASSERT(len < UINT_MAX32);
-    return err_conv(err_buffer, (uint) sizeof(err_buffer), str, (uint) len, cs);
+    len= err_conv(err_buffer, (uint) sizeof(err_buffer), str, (uint) len, cs);
+    return {err_buffer, len};
   }
-  const char *set_mysql_time(const MYSQL_TIME *ltime) const
+  LEX_CSTRING set_mysql_time(const MYSQL_TIME *ltime) const
   {
-    my_TIME_to_str(ltime, err_buffer, AUTO_SEC_PART_DIGITS);
-    return err_buffer;
+    int length= my_TIME_to_str(ltime, err_buffer, AUTO_SEC_PART_DIGITS);
+    DBUG_ASSERT(length >= 0);
+    return {err_buffer, (size_t) length};
   }
 };
 
@@ -858,7 +864,11 @@ class ErrConv: public ErrBuff
 public:
   ErrConv() {}
   virtual ~ErrConv() {}
-  virtual const char *ptr() const = 0;
+  virtual LEX_CSTRING lex_cstring() const= 0;
+  inline const char *ptr() const
+  {
+    return lex_cstring().str;
+  }
 };
 
 class ErrConvString : public ErrConv
@@ -873,7 +883,7 @@ class ErrConvString : public ErrConv
     : ErrConv(), str(str_arg), len(strlen(str_arg)), cs(cs_arg) {}
   ErrConvString(const String *s)
     : ErrConv(), str(s->ptr()), len(s->length()), cs(s->charset()) {}
-  const char *ptr() const
+  LEX_CSTRING lex_cstring() const override
   {
     return set_str(str, len, cs);
   }
@@ -884,7 +894,7 @@ class ErrConvInteger : public ErrConv, public Longlong_hybrid
 public:
   ErrConvInteger(const Longlong_hybrid &nr)
    : ErrConv(), Longlong_hybrid(nr) { }
-  const char *ptr() const
+  LEX_CSTRING lex_cstring() const override
   {
     return set_longlong(static_cast<Longlong_hybrid>(*this));
   }
@@ -895,7 +905,7 @@ class ErrConvDouble: public ErrConv
   double num;
 public:
   ErrConvDouble(double num_arg) : ErrConv(), num(num_arg) {}
-  const char *ptr() const
+  LEX_CSTRING lex_cstring() const override
   {
     return set_double(num);
   }
@@ -906,7 +916,7 @@ class ErrConvTime : public ErrConv
   const MYSQL_TIME *ltime;
 public:
   ErrConvTime(const MYSQL_TIME *ltime_arg) : ErrConv(), ltime(ltime_arg) {}
-  const char *ptr() const
+  LEX_CSTRING lex_cstring() const override
   {
     return set_mysql_time(ltime);
   }
@@ -917,7 +927,7 @@ class ErrConvDecimal : public ErrConv
   const decimal_t *d;
 public:
   ErrConvDecimal(const decimal_t *d_arg) : ErrConv(), d(d_arg) {}
-  const char *ptr() const
+  LEX_CSTRING lex_cstring() const override
   {
     return set_decimal(d);
   }

storage/connect/ha_connect.cc

@@ -3480,11 +3480,11 @@ bool ha_connect::get_error_message(int error, String* buf)
 
 		if (trace(1))
 			htrc("GEM(%d): %s\n", error, g->Message);
-
-		buf->append(ErrConvString(g->Message, strlen(g->Message),
-			&my_charset_latin1).ptr());
+                buf->append(ErrConvString(g->Message,
+                                          strlen(g->Message),
+                                          &my_charset_latin1).lex_cstring());
 	} else
-    buf->append("Cannot retrieve error message");
+          buf->append(STRING_WITH_LEN("Cannot retrieve error message"));
 
   DBUG_RETURN(false);
 } // end of get_error_message