MDEV-28835 Assertion `(length % 4) == 0' failed in my_lengthsp_utf32 on INSERT

Problem:

Item_func_date_format::val_str() and make_date_time() did not take into
account that the format string and the result string
(separately or at the same time) can be of a tricky character set
like UCS2, UTF16, UTF32. As a result, DATE_FORMAT() could generate
an ill-formed result which crashed on DBUG_ASSERTs testing well-formedness
in other parts of the code.

Fix:

1. class String changes
   Removing String::append_with_prefill(). It was not compatible with
   tricky character sets. Also it was inconvenient to use and required
   too much duplicate code on the caller side.
   Adding String::append_zerofill() instead. It's compatible with tricky
   character sets and is easier to use.
   Adding helper methods Static_binary_string::q_append_wc() and
   String::append_wc(), to append a single wide character
   (a Unicode code point in my_wc_t).

2. storage/spider changes
   Removing spider_string::append_with_prefill().
   It used String::append_with_prefix() inside, but it was unused itself.

3. Changing tricky charset incompatible code pieces in make_date_time()
   to compatible replacements:

   - Fixing the loop scanning the format string to iterate in terms
     of Unicode code points (using mb_wc()) rather than in terms
     of "char" items.
   - Using append_wc(my_wc_t) instead of append(char) to append
     a single character to the result string.
   - Using append_zerofill() instead of append_with_prefill() to
     append date/time numeric components to the result string.

mysql-test/main/ctype_binary.result

@@ -3394,5 +3394,49 @@ INSERT INTO t VALUES (0,0);
 DELETE FROM t WHERE c2<c1;
 DROP TABLE t;
 #
+# MDEV-28835 Assertion `(length % 4) == 0' failed in my_lengthsp_utf32 on INSERT
+#
+SET NAMES latin1,character_set_connection=binary;
+# Binary format, binary result
+SELECT DATE_FORMAT('2004-02-02','%W');
+DATE_FORMAT('2004-02-02','%W')
+Monday
+SELECT HEX(DATE_FORMAT('2004-02-02','%W'));
+HEX(DATE_FORMAT('2004-02-02','%W'))
+4D6F6E646179
+SELECT DATE_FORMAT(TIME'-01:01:01','%h');
+DATE_FORMAT(TIME'-01:01:01','%h')
+-01
+SELECT HEX(DATE_FORMAT(TIME'-01:01:01','%h'));
+HEX(DATE_FORMAT(TIME'-01:01:01','%h'))
+2D3031
+# latin1 format, binary result
+SELECT DATE_FORMAT('2004-02-02',_latin1'%W');
+DATE_FORMAT('2004-02-02',_latin1'%W')
+Monday
+SELECT HEX(DATE_FORMAT('2004-02-02',_latin1'%W'));
+HEX(DATE_FORMAT('2004-02-02',_latin1'%W'))
+4D6F6E646179
+SELECT DATE_FORMAT(TIME'-01:01:01',_latin1'%h');
+DATE_FORMAT(TIME'-01:01:01',_latin1'%h')
+-01
+SELECT HEX(DATE_FORMAT(TIME'-01:01:01',_latin1'%h'));
+HEX(DATE_FORMAT(TIME'-01:01:01',_latin1'%h'))
+2D3031
+# Binary format, latin1 result
+SET NAMES latin1;
+SELECT DATE_FORMAT('2004-02-02',_binary'%W');
+DATE_FORMAT('2004-02-02',_binary'%W')
+Monday
+SELECT HEX(DATE_FORMAT('2004-02-02',_binary'%W'));
+HEX(DATE_FORMAT('2004-02-02',_binary'%W'))
+4D6F6E646179
+SELECT DATE_FORMAT(TIME'-01:01:01',_binary'%h');
+DATE_FORMAT(TIME'-01:01:01',_binary'%h')
+-01
+SELECT HEX(DATE_FORMAT(TIME'-01:01:01',_binary'%h'));
+HEX(DATE_FORMAT(TIME'-01:01:01',_binary'%h'))
+2D3031
+#
 # End of 10.4 tests
 #

mysql-test/main/ctype_binary.test

@@ -241,6 +241,31 @@ INSERT INTO t VALUES (0,0);
 DELETE FROM t WHERE c2<c1;
 DROP TABLE t;
 
+--echo #
+--echo # MDEV-28835 Assertion `(length % 4) == 0' failed in my_lengthsp_utf32 on INSERT
+--echo #
+
+SET NAMES latin1,character_set_connection=binary;
+
+--echo # Binary format, binary result
+SELECT DATE_FORMAT('2004-02-02','%W');
+SELECT HEX(DATE_FORMAT('2004-02-02','%W'));
+SELECT DATE_FORMAT(TIME'-01:01:01','%h');
+SELECT HEX(DATE_FORMAT(TIME'-01:01:01','%h'));
+
+--echo # latin1 format, binary result
+SELECT DATE_FORMAT('2004-02-02',_latin1'%W');
+SELECT HEX(DATE_FORMAT('2004-02-02',_latin1'%W'));
+SELECT DATE_FORMAT(TIME'-01:01:01',_latin1'%h');
+SELECT HEX(DATE_FORMAT(TIME'-01:01:01',_latin1'%h'));
+
+--echo # Binary format, latin1 result
+SET NAMES latin1;
+SELECT DATE_FORMAT('2004-02-02',_binary'%W');
+SELECT HEX(DATE_FORMAT('2004-02-02',_binary'%W'));
+SELECT DATE_FORMAT(TIME'-01:01:01',_binary'%h');
+SELECT HEX(DATE_FORMAT(TIME'-01:01:01',_binary'%h'));
+
 --echo #
 --echo # End of 10.4 tests
 --echo #

mysql-test/main/ctype_utf32.result

@@ -2958,5 +2958,69 @@ HEX(OCT(a))
 DROP TABLE t;
 SET NAMES utf8;
 #
+# MDEV-28835 Assertion `(length % 4) == 0' failed in my_lengthsp_utf32 on INSERT
+#
+SET sql_mode='',character_set_connection=utf32;
+CREATE TABLE t (c ENUM ('','')) CHARACTER SET utf32;
+Warnings:
+Note	1291	Column 'c' has duplicated value '' in ENUM
+INSERT INTO t VALUES (DATE_FORMAT('2004-02-02','%W'));
+Warnings:
+Warning	1265	Data truncated for column 'c' at row 1
+DROP TABLE t;
+SET sql_mode=DEFAULT;
+# utf32 format, utf32 result
+SELECT DATE_FORMAT('2004-02-02','%W');
+DATE_FORMAT('2004-02-02','%W')
+Monday
+SELECT HEX(DATE_FORMAT('2004-02-02','%W'));
+HEX(DATE_FORMAT('2004-02-02','%W'))
+0000004D0000006F0000006E000000640000006100000079
+SELECT DATE_FORMAT(TIME'-01:01:01','%h');
+DATE_FORMAT(TIME'-01:01:01','%h')
+-01
+SELECT HEX(DATE_FORMAT(TIME'-01:01:01','%h'));
+HEX(DATE_FORMAT(TIME'-01:01:01','%h'))
+0000002D0000003000000031
+# utf8 format, utf32 result
+SELECT DATE_FORMAT('2004-02-02',_utf8'%W');
+DATE_FORMAT('2004-02-02',_utf8'%W')
+Monday
+SELECT HEX(DATE_FORMAT('2004-02-02',_utf8'%W'));
+HEX(DATE_FORMAT('2004-02-02',_utf8'%W'))
+0000004D0000006F0000006E000000640000006100000079
+SELECT DATE_FORMAT(TIME'-01:01:01',_utf8'%h');
+DATE_FORMAT(TIME'-01:01:01',_utf8'%h')
+-01
+SELECT HEX(DATE_FORMAT(TIME'-01:01:01',_utf8'%h'));
+HEX(DATE_FORMAT(TIME'-01:01:01',_utf8'%h'))
+0000002D0000003000000031
+# utf32 format, utf8 result
+SET NAMES utf8;
+SELECT DATE_FORMAT('2004-02-02',CONVERT('%W' USING utf32));
+DATE_FORMAT('2004-02-02',CONVERT('%W' USING utf32))
+Monday
+SELECT HEX(DATE_FORMAT('2004-02-02',CONVERT('%W' USING utf32)));
+HEX(DATE_FORMAT('2004-02-02',CONVERT('%W' USING utf32)))
+4D6F6E646179
+SELECT DATE_FORMAT(TIME'-01:01:01',CONVERT('%h' USING utf32));
+DATE_FORMAT(TIME'-01:01:01',CONVERT('%h' USING utf32))
+-01
+SELECT HEX(DATE_FORMAT(TIME'-01:01:01',CONVERT('%h' USING utf32)));
+HEX(DATE_FORMAT(TIME'-01:01:01',CONVERT('%h' USING utf32)))
+2D3031
+# non-BMP characters in format, utf8mb3 result
+# expect non-convertable characters to be replaced to '?'
+SET NAMES utf8mb3;
+SET @format= CONCAT(CONVERT('%h' USING utf32),
+_utf32 0x0010FFFF /*a non-BMP character*/,
+CONVERT('%i' USING utf32));
+SELECT DATE_FORMAT(TIME'11:22:33',@format);
+DATE_FORMAT(TIME'11:22:33',@format)
+11?22
+SELECT HEX(DATE_FORMAT(TIME'11:22:33',@format));
+HEX(DATE_FORMAT(TIME'11:22:33',@format))
+31313F3232
+#
 # End of 10.4 tests
 #

mysql-test/main/ctype_utf32.test

@@ -1120,6 +1120,48 @@ SELECT HEX(OCT(a)) FROM t;
 DROP TABLE t;
 SET NAMES utf8;
 
+--echo #
+--echo # MDEV-28835 Assertion `(length % 4) == 0' failed in my_lengthsp_utf32 on INSERT
+--echo #
+
+# --view-protocol does not yet work well with character set introducers
+
+--disable_view_protocol
+
+SET sql_mode='',character_set_connection=utf32;
+CREATE TABLE t (c ENUM ('','')) CHARACTER SET utf32;
+INSERT INTO t VALUES (DATE_FORMAT('2004-02-02','%W'));
+DROP TABLE t;
+SET sql_mode=DEFAULT;
+
+--echo # utf32 format, utf32 result
+SELECT DATE_FORMAT('2004-02-02','%W');
+SELECT HEX(DATE_FORMAT('2004-02-02','%W'));
+SELECT DATE_FORMAT(TIME'-01:01:01','%h');
+SELECT HEX(DATE_FORMAT(TIME'-01:01:01','%h'));
+
+--echo # utf8 format, utf32 result
+SELECT DATE_FORMAT('2004-02-02',_utf8'%W');
+SELECT HEX(DATE_FORMAT('2004-02-02',_utf8'%W'));
+SELECT DATE_FORMAT(TIME'-01:01:01',_utf8'%h');
+SELECT HEX(DATE_FORMAT(TIME'-01:01:01',_utf8'%h'));
+
+--echo # utf32 format, utf8 result
+SET NAMES utf8;
+SELECT DATE_FORMAT('2004-02-02',CONVERT('%W' USING utf32));
+SELECT HEX(DATE_FORMAT('2004-02-02',CONVERT('%W' USING utf32)));
+SELECT DATE_FORMAT(TIME'-01:01:01',CONVERT('%h' USING utf32));
+SELECT HEX(DATE_FORMAT(TIME'-01:01:01',CONVERT('%h' USING utf32)));
+
+--echo # non-BMP characters in format, utf8mb3 result
+--echo # expect non-convertable characters to be replaced to '?'
+SET NAMES utf8mb3;
+SET @format= CONCAT(CONVERT('%h' USING utf32),
+                    _utf32 0x0010FFFF /*a non-BMP character*/,
+                    CONVERT('%i' USING utf32));
+SELECT DATE_FORMAT(TIME'11:22:33',@format);
+SELECT HEX(DATE_FORMAT(TIME'11:22:33',@format));
+--enable_view_protocol
 
 --echo #
 --echo # End of 10.4 tests

sql/item_timefunc.cc

@@ -478,7 +478,9 @@ static bool extract_date_time(THD *thd, DATE_TIME_FORMAT *format,
   Create a formatted date/time value in a string.
 */
 
-static bool make_date_time(const LEX_CSTRING &format, MYSQL_TIME *l_time,
+static bool make_date_time(const LEX_CSTRING &format,
+                           CHARSET_INFO *format_charset,
+                           MYSQL_TIME *l_time,
                            timestamp_type type, const MY_LOCALE *locale,
                            String *str)
 {
@@ -486,21 +488,33 @@ static bool make_date_time(const LEX_CSTRING &format, MYSQL_TIME *l_time,
   uint hours_i;
   uint weekday;
   ulong length;
-  const char *ptr, *end;
+  const uchar *ptr, *end;
 
   str->length(0);
 
   if (l_time->neg)
-    str->append('-');
+    str->append_wc('-');
   
-  end= (ptr= format.str) + format.length;
-  for (; ptr != end ; ptr++)
+  end= (ptr= (const uchar *) format.str) + format.length;
+
+  for ( ; ; )
   {
-    if (*ptr != '%' || ptr+1 == end)
-      str->append(*ptr);
+    my_wc_t wc;
+    int mblen= format_charset->cset->mb_wc(format_charset, &wc, ptr, end);
+    if (mblen < 1)
+      return false;
+    ptr+= mblen;
+
+    if (wc != '%' || ptr >= end)
+      str->append_wc(wc);
     else
     {
-      switch (*++ptr) {
+      mblen= format_charset->cset->mb_wc(format_charset, &wc, ptr, end);
+      if (mblen < 1)
+        return false;
+      ptr+= mblen;
+
+      switch (wc) {
       case 'M':
         if (type == MYSQL_TIMESTAMP_TIME || !l_time->month)
           return 1;
@@ -536,8 +550,7 @@ static bool make_date_time(const LEX_CSTRING &format, MYSQL_TIME *l_time,
       case 'D':
 	if (type == MYSQL_TIMESTAMP_TIME)
 	  return 1;
-	length= (uint) (int10_to_str(l_time->day, intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 1, '0');
+	str->append_zerofill(l_time->day, 1);
 	if (l_time->day >= 10 &&  l_time->day <= 19)
 	  str->append(STRING_WITH_LEN("th"));
 	else
@@ -561,73 +574,62 @@ static bool make_date_time(const LEX_CSTRING &format, MYSQL_TIME *l_time,
       case 'Y':
         if (type == MYSQL_TIMESTAMP_TIME)
           return 1;
-	length= (uint) (int10_to_str(l_time->year, intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 4, '0');
+	str->append_zerofill(l_time->year, 4);
 	break;
       case 'y':
         if (type == MYSQL_TIMESTAMP_TIME)
           return 1;
-	length= (uint) (int10_to_str(l_time->year%100, intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 2, '0');
+	str->append_zerofill(l_time->year % 100, 2);
 	break;
       case 'm':
         if (type == MYSQL_TIMESTAMP_TIME)
           return 1;
-	length= (uint) (int10_to_str(l_time->month, intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 2, '0');
+	str->append_zerofill(l_time->month, 2);
 	break;
       case 'c':
         if (type == MYSQL_TIMESTAMP_TIME)
           return 1;
-	length= (uint) (int10_to_str(l_time->month, intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 1, '0');
+	str->append_zerofill(l_time->month, 1);
 	break;
       case 'd':
 	if (type == MYSQL_TIMESTAMP_TIME)
 	  return 1;
-	length= (uint) (int10_to_str(l_time->day, intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 2, '0');
+	str->append_zerofill(l_time->day, 2);
 	break;
       case 'e':
 	if (type == MYSQL_TIMESTAMP_TIME)
 	  return 1;
-	length= (uint) (int10_to_str(l_time->day, intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 1, '0');
+	str->append_zerofill(l_time->day, 1);
 	break;
       case 'f':
-	length= (uint) (int10_to_str(l_time->second_part, intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 6, '0');
+	str->append_zerofill((uint) l_time->second_part, 6);
 	break;
       case 'H':
-	length= (uint) (int10_to_str(l_time->hour, intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 2, '0');
+	str->append_zerofill(l_time->hour, 2);
 	break;
       case 'h':
       case 'I':
 	hours_i= (l_time->hour%24 + 11)%12+1;
-	length= (uint) (int10_to_str(hours_i, intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 2, '0');
+	str->append_zerofill(hours_i, 2);
 	break;
       case 'i':					/* minutes */
-	length= (uint) (int10_to_str(l_time->minute, intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 2, '0');
+	str->append_zerofill(l_time->minute, 2);
 	break;
       case 'j':
+      {
 	if (type == MYSQL_TIMESTAMP_TIME || !l_time->month || !l_time->year)
 	  return 1;
-	length= (uint) (int10_to_str(calc_daynr(l_time->year,l_time->month,
-					l_time->day) - 
-		     calc_daynr(l_time->year,1,1) + 1, intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 3, '0');
+        long value= calc_daynr(l_time->year,l_time->month, l_time->day) -
+                    calc_daynr(l_time->year,1,1) + 1;
+	str->append_zerofill((uint) value, 3);
 	break;
+      }
       case 'k':
-	length= (uint) (int10_to_str(l_time->hour, intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 1, '0');
+	str->append_zerofill(l_time->hour, 1);
 	break;
       case 'l':
 	hours_i= (l_time->hour%24 + 11)%12+1;
-	length= (uint) (int10_to_str(hours_i, intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 1, '0');
+	str->append_zerofill(hours_i, 1);
 	break;
       case 'p':
 	hours_i= l_time->hour%24;
@@ -643,8 +645,7 @@ static bool make_date_time(const LEX_CSTRING &format, MYSQL_TIME *l_time,
 	break;
       case 'S':
       case 's':
-	length= (uint) (int10_to_str(l_time->second, intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 2, '0');
+	str->append_zerofill(l_time->second, 2);
 	break;
       case 'T':
 	length= sprintf(intbuff, "%02d:%02d:%02d",
@@ -657,42 +658,39 @@ static bool make_date_time(const LEX_CSTRING &format, MYSQL_TIME *l_time,
 	uint year;
 	if (type == MYSQL_TIMESTAMP_TIME)
 	  return 1;
-	length= (uint) (int10_to_str(calc_week(l_time,
-				       (*ptr) == 'U' ?
-				       WEEK_FIRST_WEEKDAY : WEEK_MONDAY_FIRST,
-				       &year),
-			     intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 2, '0');
+
+        uint value= calc_week(l_time,
+                              wc == 'U' ? WEEK_FIRST_WEEKDAY :
+                                          WEEK_MONDAY_FIRST,
+                              &year);
+	str->append_zerofill(value, 2);
       }
       break;
       case 'v':
       case 'V':
       {
-	uint year;
-	if (type == MYSQL_TIMESTAMP_TIME)
-	  return 1;
-	length= (uint) (int10_to_str(calc_week(l_time,
-				       ((*ptr) == 'V' ?
-					(WEEK_YEAR | WEEK_FIRST_WEEKDAY) :
-					(WEEK_YEAR | WEEK_MONDAY_FIRST)),
-				       &year),
-			     intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 2, '0');
+        uint year;
+        if (type == MYSQL_TIMESTAMP_TIME)
+          return 1;
+        uint value= calc_week(l_time, wc == 'V' ?
+                                      (WEEK_YEAR | WEEK_FIRST_WEEKDAY) :
+                                      (WEEK_YEAR | WEEK_MONDAY_FIRST),
+                              &year);
+        str->append_zerofill(value, 2);
       }
       break;
       case 'x':
       case 'X':
       {
-	uint year;
-	if (type == MYSQL_TIMESTAMP_TIME)
-	  return 1;
-	(void) calc_week(l_time,
-			 ((*ptr) == 'X' ?
-			  WEEK_YEAR | WEEK_FIRST_WEEKDAY :
-			  WEEK_YEAR | WEEK_MONDAY_FIRST),
-			 &year);
-	length= (uint) (int10_to_str(year, intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 4, '0');
+        uint year;
+        if (type == MYSQL_TIMESTAMP_TIME)
+          return 1;
+        (void) calc_week(l_time,
+                         (wc == 'X' ?
+                          WEEK_YEAR | WEEK_FIRST_WEEKDAY :
+                          WEEK_YEAR | WEEK_MONDAY_FIRST),
+                         &year);
+        str->append_zerofill(year, 4);
       }
       break;
       case 'w':
@@ -700,12 +698,11 @@ static bool make_date_time(const LEX_CSTRING &format, MYSQL_TIME *l_time,
 	  return 1;
 	weekday=calc_weekday(calc_daynr(l_time->year,l_time->month,
 					l_time->day),1);
-	length= (uint) (int10_to_str(weekday, intbuff, 10) - intbuff);
-	str->append_with_prefill(intbuff, length, 1, '0');
+	str->append_zerofill(weekday, 1);
 	break;
 
       default:
-	str->append(*ptr);
+	str->append_wc(wc);
 	break;
       }
     }
@@ -1919,7 +1916,7 @@ String *Item_func_date_format::val_str(String *str)
 
   /* Create the result string */
   str->set_charset(collation.collation);
-  if (!make_date_time(format->lex_cstring(), &l_time,
+  if (!make_date_time(format->lex_cstring(), format->charset(), &l_time,
                       is_time_format ? MYSQL_TIMESTAMP_TIME :
                                        MYSQL_TIMESTAMP_DATE,
                       lc, str))

sql/sql_string.cc

@@ -649,24 +649,6 @@ bool String::append_parenthesized(long nr, int radix)
 }
 
 
-bool String::append_with_prefill(const char *s,uint32 arg_length,
-		 uint32 full_length, char fill_char)
-{
-  int t_length= arg_length > full_length ? arg_length : full_length;
-
-  if (realloc_with_extra_if_needed(str_length + t_length))
-    return TRUE;
-  t_length= full_length - arg_length;
-  if (t_length > 0)
-  {
-    bfill(Ptr+str_length, t_length, fill_char);
-    str_length=str_length + t_length;
-  }
-  append(s, arg_length);
-  return FALSE;
-}
-
-
 int Static_binary_string::strstr(const Static_binary_string &s, uint32 offset)
 {
   if (s.length()+offset <= str_length)

sql/sql_string.h

@@ -392,6 +392,19 @@ class Static_binary_string : public Sql_alloc
     float8store(Ptr + str_length, *d);
     str_length += 8;
   }
+  /*
+    Append a wide character.
+    The caller must have allocated at least cs->mbmaxlen bytes.
+  */
+  int q_append_wc(my_wc_t wc, CHARSET_INFO *cs)
+  {
+    int mblen;
+    if ((mblen= cs->cset->wc_mb(cs, wc,
+                                (uchar *) end(),
+                                (uchar *) end() + cs->mbmaxlen)) > 0)
+      str_length+= (uint32) mblen;
+    return mblen;
+  }
   void q_append(const char *data, size_t data_len)
   {
     if (data_len)
@@ -1009,8 +1022,6 @@ class String: public Charset, public Binary_string
       (quot && append(quot));
   }
   bool append(const char *s, size_t size);
-  bool append_with_prefill(const char *s, uint32 arg_length,
-			   uint32 full_length, char fill_char);
   bool append_parenthesized(long nr, int radix= 10);
 
   // Append with optional character set conversion from cs to charset()
@@ -1020,6 +1031,31 @@ class String: public Charset, public Binary_string
     return append(s.str, s.length, cs);
   }
 
+  // Append a wide character
+  bool append_wc(my_wc_t wc)
+  {
+    if (reserve(mbmaxlen()))
+      return true;
+    int mblen= q_append_wc(wc, charset());
+    if (mblen > 0)
+      return false;
+    else if (mblen == MY_CS_ILUNI && wc != '?')
+      return q_append_wc('?', charset()) <= 0;
+    return true;
+  }
+
+  // Append a number with zero prefilling
+  bool append_zerofill(uint num, uint width)
+  {
+    static const char zeros[15]= "00000000000000";
+    char intbuff[15];
+    uint length= (uint) (int10_to_str(num, intbuff, 10) - intbuff);
+    if (length < width &&
+        append(zeros, width - length, &my_charset_latin1))
+      return true;
+    return append(intbuff, length, &my_charset_latin1);
+  }
+
   /*
     Append a bitmask in an uint32 with a translation into a
     C-style human readable representation, e.g.:

storage/spider/spd_db_include.h

@@ -445,12 +445,6 @@ class spider_string
     IO_CACHE *file,
     uint32 arg_length
   );
-  bool append_with_prefill(
-    const char *s,
-    uint32 arg_length,
-    uint32 full_length,
-    char fill_char
-  );
   int strstr(
     const String &search,
     uint32 offset = 0

storage/spider/spd_malloc.cc

@@ -941,23 +941,6 @@ bool spider_string::append(
   DBUG_RETURN(res);
 }
 
-bool spider_string::append_with_prefill(
-  const char *s,
-  uint32 arg_length,
-  uint32 full_length,
-  char fill_char
-) {
-  DBUG_ENTER("spider_string::append_with_prefill");
-  DBUG_PRINT("info",("spider this=%p", this));
-  DBUG_ASSERT(mem_calc_inited);
-  DBUG_ASSERT((!current_alloc_mem && !str.is_alloced()) ||
-    current_alloc_mem == str.alloced_length());
-  bool res = str.append_with_prefill(s, arg_length, full_length,
-    fill_char);
-  SPIDER_STRING_CALC_MEM;
-  DBUG_RETURN(res);
-}
-
 int spider_string::strstr(
   const String &search,
   uint32 offset