Bug#45012 my_like_range_cp932 generates invalid string

Problem: The functions my_like_range_xxx() returned
badly formed maximum strings for Asian character sets,
which made problems for storage engines.

Fix: 
- Removed a number my_like_range_xxx() implementations,
  which were in fact dumplicate code pieces.
- Using generic my_like_range_mb() instead.
- Setting max_sort_char member properly for Asian character sets
- Adding unittest/strings/strings-t.c, 
  to test that my_like_range_xxx() return well-formed 
  min and max strings.

Notes:

- No additional tests in mysql/t/ available.
  Old tests cover the affected code well enough.

1 files changed, 3 insertions, 83 deletions

diff --git a/strings/ctype-big5.c b/strings/ctype-big5.c
index 3da307b82fc..2cb40c266d2 100644
--- a/strings/ctype-big5.c
+++ b/strings/ctype-big5.c
@@ -377,86 +377,6 @@ static int my_strxfrm_big5(uchar *dest, const uchar *src, int len)
 #endif
 
 
-/*
-** Calculate min_str and max_str that ranges a LIKE string.
-** Arguments:
-** ptr		Pointer to LIKE string.
-** ptr_length	Length of LIKE string.
-** escape	Escape character in LIKE.  (Normally '\').
-**		All escape characters should be removed from min_str and max_str
-** res_length   Length of min_str and max_str.
-** min_str      Smallest case sensitive string that ranges LIKE.
-**		Should be space padded to res_length.
-** max_str	Largest case sensitive string that ranges LIKE.
-**		Normally padded with the biggest character sort value.
-**
-** The function should return 0 if ok and 1 if the LIKE string can't be
-** optimized !
-*/
-
-#define max_sort_char ((char) 255)
-
-static my_bool my_like_range_big5(CHARSET_INFO *cs __attribute__((unused)),
-				  const char *ptr,size_t ptr_length,
-				  pbool escape, pbool w_one, pbool w_many,
-				  size_t res_length,
-                                  char *min_str, char *max_str,
-				  size_t *min_length, size_t *max_length)
-{
-  const char *end= ptr + ptr_length;
-  char *min_org=min_str;
-  char *min_end=min_str+res_length;
-  size_t charlen= res_length / cs->mbmaxlen;
-
-  for (; ptr != end && min_str != min_end && charlen > 0; ptr++, charlen--)
-  {
-    if (ptr+1 != end && isbig5code(ptr[0],ptr[1]))
-    {
-      *min_str++= *max_str++ = *ptr++;
-      *min_str++= *max_str++ = *ptr;
-      continue;
-    }
-    if (*ptr == escape && ptr+1 != end)
-    {
-      ptr++;				/* Skip escape */
-      if (isbig5code(ptr[0], ptr[1]))
-        *min_str++= *max_str++ = *ptr++;
-      if (min_str < min_end)
-        *min_str++= *max_str++= *ptr;
-      continue;
-    }
-    if (*ptr == w_one)			/* '_' in SQL */
-    {
-      *min_str++='\0';			/* This should be min char */
-      *max_str++=max_sort_char;
-      continue;
-    }
-    if (*ptr == w_many)		/* '%' in SQL */
-    {
-      /*
-        Calculate length of keys:
-        'a\0\0... is the smallest possible string when we have space expand
-        a\ff\ff... is the biggest possible string
-      */
-      *min_length= ((cs->state & MY_CS_BINSORT) ? (size_t) (min_str - min_org) :
-                    res_length);
-      *max_length= res_length;
-      do {
-	*min_str++ = 0;
-	*max_str++ = max_sort_char;
-      } while (min_str != min_end);
-      return 0;
-    }
-    *min_str++= *max_str++ = *ptr;
-  }
-
- *min_length= *max_length= (size_t) (min_str-min_org);
-  while (min_str != min_end)
-    *min_str++= *max_str++= ' ';
-  return 0;
-}
-
-
 static uint ismbchar_big5(CHARSET_INFO *cs __attribute__((unused)),
                          const char* p, const char *e)
 {
@@ -6338,7 +6258,7 @@ static MY_COLLATION_HANDLER my_collation_big5_chinese_ci_handler =
   my_strnncollsp_big5,
   my_strnxfrm_big5,
   my_strnxfrmlen_simple,
-  my_like_range_big5,
+  my_like_range_mb,
   my_wildcmp_mb,
   my_strcasecmp_mb,
   my_instr_mb,
@@ -6402,7 +6322,7 @@ CHARSET_INFO my_charset_big5_chinese_ci=
     1,			/* mbminlen   */
     2,			/* mbmaxlen   */
     0,			/* min_sort_char */
-    255,		/* max_sort_char */
+    0xF9D5,		/* max_sort_char */
     ' ',                /* pad char      */
     1,                  /* escape_with_backslash_is_dangerous */
     &my_charset_big5_handler,
@@ -6435,7 +6355,7 @@ CHARSET_INFO my_charset_big5_bin=
     1,			/* mbminlen   */
     2,			/* mbmaxlen   */
     0,			/* min_sort_char */
-    255,		/* max_sort_char */
+    0xF9FE,		/* max_sort_char */
     ' ',                /* pad char      */
     1,                  /* escape_with_backslash_is_dangerous */
     &my_charset_big5_handler,