mariadb/sql/sql_string.h

#ifndef SQL_STRING_INCLUDED
#define SQL_STRING_INCLUDED

/*
   Copyright (c) 2000, 2013, Oracle and/or its affiliates.
   Copyright (c) 2008, 2020, MariaDB Corporation.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335  USA */

/* This file is originally from the mysql distribution. Coded by monty */

#ifdef USE_PRAGMA_INTERFACE
#pragma interface			/* gcc class implementation */
#endif

#include "m_ctype.h"                            /* my_charset_bin */
#include <my_sys.h>              /* alloc_root, my_free, my_realloc */
#include "m_string.h"                           /* TRASH */
#include "sql_list.h"

class String;
#ifdef MYSQL_SERVER
extern PSI_memory_key key_memory_String_value;
#define STRING_PSI_MEMORY_KEY key_memory_String_value
#else
#define STRING_PSI_MEMORY_KEY PSI_NOT_INSTRUMENTED
#endif

typedef struct st_io_cache IO_CACHE;
typedef struct st_mem_root MEM_ROOT;

#include "pack.h"
int sortcmp(const String *a,const String *b, CHARSET_INFO *cs);
String *copy_if_not_alloced(String *a,String *b,uint32 arg_length);
inline uint32 copy_and_convert(char *to, size_t to_length,
                               CHARSET_INFO *to_cs,
                               const char *from, size_t from_length,
                               CHARSET_INFO *from_cs, uint *errors)
{
  return my_convert(to, (uint)to_length, to_cs, from, (uint)from_length, from_cs, errors);
}


class String_copy_status: protected MY_STRCOPY_STATUS
{
public:
  const char *source_end_pos() const
  { return m_source_end_pos; }
  const char *well_formed_error_pos() const
  { return m_well_formed_error_pos; }
};


class Well_formed_prefix_status: public String_copy_status
{
public:
  Well_formed_prefix_status(CHARSET_INFO *cs,
                            const char *str, const char *end, size_t nchars)
  { cs->well_formed_char_length(str, end, nchars, this); }
};


class Well_formed_prefix: public Well_formed_prefix_status
{
  const char *m_str; // The beginning of the string
public:
  Well_formed_prefix(CHARSET_INFO *cs, const char *str, const char *end,
                     size_t nchars)
   :Well_formed_prefix_status(cs, str, end, nchars), m_str(str)
  { }
  Well_formed_prefix(CHARSET_INFO *cs, const char *str, size_t length,
                     size_t nchars)
   :Well_formed_prefix_status(cs, str, str + length, nchars), m_str(str)
  { }
  Well_formed_prefix(CHARSET_INFO *cs, const char *str, size_t length)
   :Well_formed_prefix_status(cs, str, str + length, length), m_str(str)
  { }
  Well_formed_prefix(CHARSET_INFO *cs, LEX_CSTRING str, size_t nchars)
   :Well_formed_prefix_status(cs, str.str, str.str + str.length, nchars),
    m_str(str.str)
  { }
  size_t length() const { return m_source_end_pos - m_str; }
};


class String_copier: public String_copy_status,
                     protected MY_STRCONV_STATUS
{
public:
  const char *cannot_convert_error_pos() const
  { return m_cannot_convert_error_pos; }
  const char *most_important_error_pos() const
  {
    return well_formed_error_pos() ? well_formed_error_pos() :
                                     cannot_convert_error_pos();
  }
  /*
    Convert a string between character sets.
    "dstcs" and "srccs" cannot be &my_charset_bin.
  */
  size_t convert_fix(CHARSET_INFO *dstcs, char *dst, size_t dst_length,
                     CHARSET_INFO *srccs, const char *src, size_t src_length, size_t nchars)
  {
    return my_convert_fix(dstcs, dst, dst_length,
                          srccs, src, src_length, nchars, this, this);
  }
  /*
     Copy a string. Fix bad bytes/characters to '?'.
  */
  uint well_formed_copy(CHARSET_INFO *to_cs, char *to, size_t to_length,
                        CHARSET_INFO *from_cs, const char *from, size_t from_length, size_t nchars);
  // Same as above, but without the "nchars" limit.
  uint well_formed_copy(CHARSET_INFO *to_cs, char *to, size_t to_length,
                        CHARSET_INFO *from_cs, const char *from, size_t from_length)
  {
    return well_formed_copy(to_cs, to, to_length,
                            from_cs, from, from_length,
                            from_length /* No limit on "nchars"*/);
  }
};


size_t my_copy_with_hex_escaping(CHARSET_INFO *cs,
                                 char *dst, size_t dstlen,
                                 const char *src, size_t srclen);
uint convert_to_printable(char *to, size_t to_len,
                          const char *from, size_t from_len,
                          CHARSET_INFO *from_cs, size_t nbytes= 0);
size_t convert_to_printable_required_length(uint len);


class Charset
{
  CHARSET_INFO *m_charset;
public:
  Charset() :m_charset(&my_charset_bin) { }
  Charset(CHARSET_INFO *cs) :m_charset(cs) { }

  CHARSET_INFO *charset() const { return m_charset; }
  bool use_mb() const { return m_charset->use_mb(); }
  uint mbminlen() const { return m_charset->mbminlen; }
  uint mbmaxlen() const { return m_charset->mbmaxlen; }
  bool is_good_for_ft() const
  {
    // Binary and UCS2/UTF16/UTF32 are not supported
    return m_charset != &my_charset_bin && m_charset->mbminlen == 1;
  }

  size_t numchars(const char *str, const char *end) const
  {
    return m_charset->numchars(str, end);
  }
  size_t lengthsp(const char *str, size_t length) const
  {
    return m_charset->lengthsp(str, length);
  }
  size_t charpos(const char *str, const char *end, size_t pos) const
  {
    return m_charset->charpos(str, end, pos);
  }
  void set_charset(CHARSET_INFO *charset_arg)
  {
    m_charset= charset_arg;
  }
  void set_charset(const Charset &other)
  {
    m_charset= other.m_charset;
  }
  void swap(Charset &other)
  {
    swap_variables(CHARSET_INFO*, m_charset, other.m_charset);
  }
  bool same_encoding(const Charset &other) const
  {
    return !strcmp(m_charset->csname, other.m_charset->csname);
  }
  /*
    Collation name without the character set name.
    For example, in case of "latin1_swedish_ci",
    this method returns "_swedish_ci".
  */
  LEX_CSTRING collation_specific_name() const;
  bool encoding_allows_reinterpret_as(CHARSET_INFO *cs) const;
  bool eq_collation_specific_names(CHARSET_INFO *cs) const;
  bool can_have_collate_clause() const
  {
    return m_charset != &my_charset_bin;
  }

  /*
    The MariaDB version when the last collation change happened,
    e.g. due to a bug fix. See functions below.
  */
  static ulong latest_mariadb_version_with_collation_change()
  {
    return 110002;
  }

  /*
    Check if the collation with the given ID changed its order
    since the given MariaDB version.
  */
  static bool collation_changed_order(ulong mysql_version, uint cs_number)
  {
    if ((mysql_version < 50048 &&
           (cs_number == 11 || /* ascii_general_ci - bug #29499, bug #27562 */
            cs_number == 41 || /* latin7_general_ci - bug #29461 */
            cs_number == 42 || /* latin7_general_cs - bug #29461 */
            cs_number == 20 || /* latin7_estonian_cs - bug #29461 */
            cs_number == 21 || /* latin2_hungarian_ci - bug #29461 */
            cs_number == 22 || /* koi8u_general_ci - bug #29461 */
            cs_number == 23 || /* cp1251_ukrainian_ci - bug #29461 */
            cs_number == 26)) || /* cp1250_general_ci - bug #29461 */
           (mysql_version < 50124 &&
           (cs_number == 33 || /* utf8mb3_general_ci - bug #27877 */
            cs_number == 35))) /* ucs2_general_ci - bug #27877 */
        return true;

    if (cs_number == 159 && /* ucs2_general_mysql500_ci - MDEV-30746 */
        ((mysql_version >= 100400 && mysql_version < 100429) ||
         (mysql_version >= 100500 && mysql_version < 100520) ||
         (mysql_version >= 100600 && mysql_version < 100613) ||
         (mysql_version >= 100700 && mysql_version < 100708) ||
         (mysql_version >= 100800 && mysql_version < 100808) ||
         (mysql_version >= 100900 && mysql_version < 100906) ||
         (mysql_version >= 101000 && mysql_version < 101004) ||
         (mysql_version >= 101100 && mysql_version < 101103) ||
         (mysql_version >= 110000 && mysql_version < 110002)))
      return true;
    return false;
  }

  /**
     Check if a collation has changed ID since the given version.
     Return the new ID.

     @param mysql_version
     @param cs_number     - collation ID

     @retval the new collation ID (or cs_number, if no change)
  */

  static uint upgrade_collation_id(ulong mysql_version, uint cs_number)
  {
    if (mysql_version >= 50300 && mysql_version <= 50399)
    {
      switch (cs_number) {
      case 149: return MY_PAGE2_COLLATION_ID_UCS2;   // ucs2_crotian_ci
      case 213: return MY_PAGE2_COLLATION_ID_UTF8;   // utf8_crotian_ci
      }
    }
    if ((mysql_version >= 50500 && mysql_version <= 50599) ||
        (mysql_version >= 100000 && mysql_version <= 100005))
    {
      switch (cs_number) {
      case 149: return MY_PAGE2_COLLATION_ID_UCS2;   // ucs2_crotian_ci
      case 213: return MY_PAGE2_COLLATION_ID_UTF8;   // utf8_crotian_ci
      case 214: return MY_PAGE2_COLLATION_ID_UTF32;  // utf32_croatian_ci
      case 215: return MY_PAGE2_COLLATION_ID_UTF16;  // utf16_croatian_ci
      case 245: return MY_PAGE2_COLLATION_ID_UTF8MB4;// utf8mb4_croatian_ci
      }
    }
    return cs_number;
  }

};


/*
  A storage for String.
  Should be eventually derived from LEX_STRING.
*/
class Static_binary_string : public Sql_alloc
{
protected:
  char *Ptr;
  uint32 str_length;
public:
  Static_binary_string()
   :Ptr(NULL),
    str_length(0)
  { }
  Static_binary_string(char *str, size_t length_arg)
   :Ptr(str),
    str_length((uint32) length_arg)
  {
    DBUG_ASSERT(length_arg < UINT_MAX32);
  }
  inline uint32 length() const { return str_length;}
  inline char& operator [] (size_t i) const { return Ptr[i]; }
  inline void length(size_t len) { str_length=(uint32)len ; }
  inline bool is_empty() const { return (str_length == 0); }
  inline const char *ptr() const { return Ptr; }
  inline const char *end() const { return Ptr + str_length; }
  bool has_8bit_bytes() const
  {
    for (const char *c= ptr(), *c_end= end(); c < c_end; c++)
    {
      if (!my_isascii(*c))
        return true;
    }
    return false;
  }

  bool bin_eq(const Static_binary_string *other) const
  {
    return length() == other->length() &&
           !memcmp(ptr(), other->ptr(), length());
  }

  void set(char *str, size_t len)
  {
    Ptr= str;
    str_length= (uint32) len;
  }

  void swap(Static_binary_string &s)
  {
    swap_variables(char *, Ptr, s.Ptr);
    swap_variables(uint32, str_length, s.str_length);
  }

  /*
    PMG 2004.11.12
    This is a method that works the same as perl's "chop". It simply
    drops the last character of a string. This is useful in the case
    of the federated storage handler where I'm building a unknown
    number, list of values and fields to be used in a sql insert
    statement to be run on the remote server, and have a comma after each.
    When the list is complete, I "chop" off the trailing comma

    ex.
      String stringobj;
      stringobj.append("VALUES ('foo', 'fi', 'fo',");
      stringobj.chop();
      stringobj.append(")");

    In this case, the value of string was:

    VALUES ('foo', 'fi', 'fo',
    VALUES ('foo', 'fi', 'fo'
    VALUES ('foo', 'fi', 'fo')
  */
  inline void chop()
  {
    str_length--;
    Ptr[str_length]= '\0';
    DBUG_ASSERT(strlen(Ptr) == str_length);
  }

  // Returns offset to substring or -1
  int strstr(const Static_binary_string &search, uint32 offset=0);
  // Returns offset to substring or -1
  int strrstr(const Static_binary_string &search, uint32 offset=0);

  /*
    The following append operations do NOT check alloced memory
    q_*** methods writes values of parameters itself
    qs_*** methods writes string representation of value
  */
  void q_append(const char c)
  {
    Ptr[str_length++] = c;
  }
  void q_append2b(const uint32 n)
  {
    int2store(Ptr + str_length, n);
    str_length += 2;
  }
  void q_append(const uint32 n)
  {
    int4store(Ptr + str_length, n);
    str_length += 4;
  }
  void q_append(double d)
  {
    float8store(Ptr + str_length, d);
    str_length += 8;
  }
  void q_append(double *d)
  {
    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)
      memcpy(Ptr + str_length, data, data_len);
    DBUG_ASSERT(str_length <= UINT_MAX32 - data_len);
    str_length += (uint)data_len;
  }
  void q_append(const LEX_CSTRING *ls)
  {
    DBUG_ASSERT(ls->length < UINT_MAX32 &&
                ((ls->length == 0 && !ls->str) ||
                 ls->length == strlen(ls->str)));
    q_append(ls->str, (uint32) ls->length);
  }

  void write_at_position(int position, uint32 value)
  {
    int4store(Ptr + position,value);
  }

  void qs_append(const char *str)
  {
    qs_append(str, (uint32)strlen(str));
  }
  void qs_append(const LEX_CSTRING *ls)
  {
    DBUG_ASSERT(ls->length < UINT_MAX32 &&
                ((ls->length == 0 && !ls->str) ||
                 ls->length == strlen(ls->str)));
    qs_append(ls->str, (uint32)ls->length);
  }
  void qs_append(const char *str, size_t len);
  void qs_append_hex(const char *str, uint32 len);
  void qs_append_hex_uint32(uint32 num);
  void qs_append(double d);
  void qs_append(const double *d);
  inline void qs_append(const char c)
  {
     Ptr[str_length]= c;
     str_length++;
  }
  void qs_append(int i);
  void qs_append(uint i)
  {
    qs_append((ulonglong)i);
  }
  void qs_append(ulong i)
  {
    qs_append((ulonglong)i);
  }
  void qs_append(ulonglong i);
  void qs_append(longlong i, int radix)
  {
    char *buff= Ptr + str_length;
    char *end= ll2str(i, buff, radix, 0);
    str_length+= uint32(end-buff);
  }
};


class Binary_string: public Static_binary_string
{
  uint32 Alloced_length, extra_alloc;
  bool alloced, thread_specific;
  void init_private_data()
  {
    Alloced_length= extra_alloc= 0;
    alloced= thread_specific= false;
  }
public:
  Binary_string()
  {
    init_private_data();
  }
  explicit Binary_string(size_t length_arg)
  {
    init_private_data();
    (void) real_alloc(length_arg);
  }
  explicit Binary_string(const char *str)
   :Binary_string(str, strlen(str))
  { }
  /*
    NOTE: If one intend to use the c_ptr() method, the following two
    contructors need the size of memory for STR to be at least LEN+1 (to make
    room for zero termination).
  */
  Binary_string(const char *str, size_t len)
   :Static_binary_string((char *) str, len)
  {
    init_private_data();
  }
  Binary_string(char *str, size_t len)
   :Static_binary_string(str, len)
  {
    Alloced_length= (uint32) len;
    extra_alloc= 0;
    alloced= thread_specific= 0;
  }
  explicit Binary_string(const Binary_string &str)
   :Static_binary_string(str)
  {
    Alloced_length= str.Alloced_length;
    extra_alloc= 0;
    alloced= thread_specific= 0;
  }

  ~Binary_string() { free(); }

  /* Mark variable thread specific it it's not allocated already */
  inline void set_thread_specific()
  {
    if (!alloced)
      thread_specific= 1;
  }
  bool is_alloced() const { return alloced; }
  inline uint32 alloced_length() const { return Alloced_length;}
  inline uint32 extra_allocation() const { return extra_alloc;}
  inline void extra_allocation(size_t len) { extra_alloc= (uint32)len; }
  inline void mark_as_const() { Alloced_length= 0;}

  inline bool uses_buffer_owned_by(const Binary_string *s) const
  {
    return (s->alloced && Ptr >= s->Ptr && Ptr < s->Ptr + s->str_length);
  }

  /* Swap two string objects. Efficient way to exchange data without memcpy. */
  void swap(Binary_string &s)
  {
    Static_binary_string::swap(s);
    swap_variables(uint32, Alloced_length, s.Alloced_length);
    swap_variables(bool, alloced, s.alloced);
  }

  /**
     Points the internal buffer to the supplied one. The old buffer is freed.
     @param str Pointer to the new buffer.
     @param arg_length Length of the new buffer in characters, excluding any
            null character.
     @note The new buffer will not be null terminated.
  */
  void set_alloced(char *str, size_t length_arg, size_t alloced_length_arg)
  {
    free();
    Static_binary_string::set(str, length_arg);
    DBUG_ASSERT(alloced_length_arg < UINT_MAX32);
    Alloced_length= (uint32) alloced_length_arg;
  }
  inline void set(char *str, size_t arg_length)
  {
    set_alloced(str, arg_length, arg_length);
  }
  inline void set(const char *str, size_t arg_length)
  {
    free();
    Static_binary_string::set((char *) str, arg_length);
  }

  void set(Binary_string &str, size_t offset, size_t arg_length)
  {
    DBUG_ASSERT(&str != this);
    free();
    Static_binary_string::set((char*) str.ptr() + offset, arg_length);
    if (str.Alloced_length)
      Alloced_length= (uint32) (str.Alloced_length - offset);
  }
  LEX_CSTRING to_lex_cstring() const
  {
    LEX_CSTRING tmp= {Ptr, str_length};
    return tmp;
  }
  inline LEX_CSTRING *get_value(LEX_CSTRING *res)
  {
    res->str=    Ptr;
    res->length= str_length;
    return res;
  }

  /* Take over handling of buffer from some other object */
  void reset(char *ptr_arg, size_t length_arg, size_t alloced_length_arg)
  {
    set_alloced(ptr_arg, length_arg, alloced_length_arg);
    alloced= ptr_arg != 0;
  }

  /* Forget about the buffer, let some other object handle it */
  char *release()
  {
    char *old= Ptr;
    Static_binary_string::set(NULL, 0);
    init_private_data();
    return old;
  }

  inline void set_quick(char *str, size_t arg_length)
  {
    if (!alloced)
    {
      Static_binary_string::set(str, arg_length);
      Alloced_length= (uint32) arg_length;
    }
  }

  inline Binary_string& operator=(const Binary_string &s)
  {
    if (&s != this)
    {
      /*
        It is forbidden to do assignments like
        some_string = substring_of_that_string
      */
      DBUG_ASSERT(!s.uses_buffer_owned_by(this));
      set_alloced((char *) s.Ptr, s.str_length, s.Alloced_length);
    }
    return *this;
  }

  bool set_hex(ulonglong num);
  bool set_hex(const char *str, uint32 len);
  bool set_fcvt(double num, uint decimals);

  bool copy();                                  // Alloc string if not alloced
  bool copy(const Binary_string &s);            // Allocate new string
  bool copy(const char *s, size_t arg_length);	// Allocate new string
  bool copy_or_move(const char *s,size_t arg_length);

  /**
    Convert a string to a printable format.
    All non-convertable and control characters are replaced to 5-character
    sequences '\hhhh'.
  */
  bool copy_printable_hhhh(CHARSET_INFO *to_cs,
                           CHARSET_INFO *from_cs,
                           const char *from, size_t from_length);

  bool append_ulonglong(ulonglong val);
  bool append_longlong(longlong val);

  bool append(const char *s, size_t size)
  {
    if (!size)
      return false;
    if (realloc_with_extra_if_needed(str_length + size))
      return true;
    q_append(s, size);
    return false;
  }
  bool append(const LEX_CSTRING &s)
  {
    return append(s.str, s.length);
  }
  bool append(const Binary_string &s)
  {
    return append(s.ptr(), s.length());
  }
  bool append(IO_CACHE* file, uint32 arg_length);

  inline bool append_char(char chr)
  {
    if (str_length < Alloced_length)
    {
      Ptr[str_length++]= chr;
    }
    else
    {
      if (unlikely(realloc_with_extra(str_length + 1)))
	return true;
      Ptr[str_length++]= chr;
    }
    return false;
  }
  bool append_hex(const char *src, uint32 srclen)
  {
    for (const char *src_end= src + srclen ; src != src_end ; src++)
    {
      if (unlikely(append_char(_dig_vec_lower[((uchar) *src) >> 4])) ||
          unlikely(append_char(_dig_vec_lower[((uchar) *src) & 0x0F])))
        return true;
    }
    return false;
  }
  bool append_hex_uint32(uint32 num)
  {
    if (reserve(8))
      return true;
    qs_append_hex_uint32(num);
    return false;
  }
  bool append_with_step(const char *s, uint32 arg_length, uint32 step_alloc)
  {
    uint32 new_length= arg_length + str_length;
    if (new_length > Alloced_length &&
        unlikely(realloc(new_length + step_alloc)))
      return true;
    q_append(s, arg_length);
    return false;
  }

  inline char *c_ptr()
  {
    DBUG_ASSERT(!alloced || !Ptr || !Alloced_length ||
                (Alloced_length >= (str_length + 1)));

    if (!Ptr || Ptr[str_length])              // Should be safe
      (void) realloc(str_length);
    return Ptr;
  }
  inline char *c_ptr_quick()
  {
    if (Ptr && str_length < Alloced_length)
      Ptr[str_length]=0;
    return Ptr;
  }
  inline char *c_ptr_safe()
  {
    if (Ptr && str_length < Alloced_length)
      Ptr[str_length]=0;
    else
      (void) realloc(str_length);
    return Ptr;
  }

  inline void free()
  {
    if (alloced)
    {
      alloced=0;
      my_free(Ptr);
    }
    Alloced_length= extra_alloc= 0;
    Static_binary_string::set(NULL, 0); // Safety
  }
  inline bool alloc(size_t arg_length)
  {
    if (arg_length < Alloced_length)
      return 0;
    return real_alloc(arg_length);
  }
  bool real_alloc(size_t arg_length);  // Empties old string
  bool realloc_raw(size_t arg_length);
  bool realloc(size_t arg_length)
  {
    if (realloc_raw(arg_length))
      return TRUE;
    Ptr[arg_length]= 0; // This make other funcs shorter
    return FALSE;
  }
  bool realloc_with_extra(size_t arg_length)
  {
    if (extra_alloc < 4096)
      extra_alloc= extra_alloc*2+128;
    if (realloc_raw(arg_length + extra_alloc))
      return TRUE;
    Ptr[arg_length]=0;        // This make other funcs shorter
    return FALSE;
  }
  bool realloc_with_extra_if_needed(size_t arg_length)
  {
    if (arg_length < Alloced_length)
    {
      Ptr[arg_length]=0; // behave as if realloc was called.
      return 0;
    }
    return realloc_with_extra(arg_length);
  }
  // Shrink the buffer, but only if it is allocated on the heap.
  void shrink(size_t arg_length);

  void move(Binary_string &s)
  {
    set_alloced(s.Ptr, s.str_length, s.Alloced_length);
    extra_alloc= s.extra_alloc;
    alloced= s.alloced;
    thread_specific= s.thread_specific;
    s.alloced= 0;
  }
  bool fill(uint32 max_length,char fill);
  /*
    Replace substring with string
    If wrong parameter or not enough memory, do nothing
  */
  bool replace(uint32 offset,uint32 arg_length, const char *to, uint32 length);
  bool replace(uint32 offset,uint32 arg_length, const Static_binary_string &to)
  {
    return replace(offset,arg_length,to.ptr(),to.length());
  }

  int reserve(size_t space_needed)
  {
    DBUG_ASSERT((ulonglong) str_length + space_needed < UINT_MAX32);
    return realloc(str_length + space_needed);
  }
  int reserve(size_t space_needed, size_t grow_by);

  inline char *prep_append(uint32 arg_length, uint32 step_alloc)
  {
    uint32 new_length= arg_length + str_length;
    if (new_length > Alloced_length)
    {
      if (unlikely(realloc(new_length + step_alloc)))
        return 0;
    }
    uint32 old_length= str_length;
    str_length+= arg_length;
    return Ptr + old_length;                  // Area to use
  }


  void q_net_store_length(ulonglong length)
  {
    DBUG_ASSERT(Alloced_length >= (str_length + net_length_size(length)));
    char *pos= (char *) net_store_length((uchar *)(Ptr + str_length), length);
    str_length= uint32(pos - Ptr);
  }
  void q_net_store_data(const uchar *from, size_t length)
  {
    DBUG_ASSERT(length < UINT_MAX32);
    DBUG_ASSERT(Alloced_length >= (str_length + length +
                                   net_length_size(length)));
    q_net_store_length(length);
    q_append((const char *)from, (uint32) length);
  }
};


class String: public Charset, public Binary_string
{
public:
  String() = default;
  String(size_t length_arg)
   :Binary_string(length_arg)
  { }
  String(const char *str, CHARSET_INFO *cs)
   :Charset(cs),
    Binary_string(str)
  { }
  /*
    NOTE: If one intend to use the c_ptr() method, the following two
    contructors need the size of memory for STR to be at least LEN+1 (to make
    room for zero termination).
  */
  String(const char *str, size_t len, CHARSET_INFO *cs)
   :Charset(cs),
    Binary_string((char *) str, len)
  { }
  String(char *str, size_t len, CHARSET_INFO *cs)
   :Charset(cs),
    Binary_string(str, len)
  { }
  String(const String &str) = default;

  void set(String &str,size_t offset,size_t arg_length)
  {
    Binary_string::set(str, offset, arg_length);
    set_charset(str);
  }
  inline void set(char *str,size_t arg_length, CHARSET_INFO *cs)
  {
    Binary_string::set(str, arg_length);
    set_charset(cs);
  }
  inline void set(const char *str,size_t arg_length, CHARSET_INFO *cs)
  {
    Binary_string::set(str, arg_length);
    set_charset(cs);
  }
  bool set_ascii(const char *str, size_t arg_length);
  inline void set_quick(char *str,size_t arg_length, CHARSET_INFO *cs)
  {
    Binary_string::set_quick(str, arg_length);
    set_charset(cs);
  }
  bool set_int(longlong num, bool unsigned_flag, CHARSET_INFO *cs);
  bool set(int num, CHARSET_INFO *cs) { return set_int(num, false, cs); }
  bool set(uint num, CHARSET_INFO *cs) { return set_int(num, true, cs); }
  bool set(long num, CHARSET_INFO *cs) { return set_int(num, false, cs); }
  bool set(ulong num, CHARSET_INFO *cs) { return set_int(num, true, cs); }
  bool set(longlong num, CHARSET_INFO *cs) { return set_int(num, false, cs); }
  bool set(ulonglong num, CHARSET_INFO *cs) { return set_int((longlong)num, true, cs); }
  bool set_real(double num,uint decimals, CHARSET_INFO *cs);
  bool set_fcvt(double num, uint decimals)
  {
    set_charset(&my_charset_latin1);
    return Binary_string::set_fcvt(num, decimals);
  }

  bool set_hex(ulonglong num)
  {
    set_charset(&my_charset_latin1);
    return Binary_string::set_hex(num);
  }
  bool set_hex(const char *str, uint32 len)
  {
    set_charset(&my_charset_latin1);
    return Binary_string::set_hex(str, len);
  }

  /* Take over handling of buffer from some other object */
  void reset(char *ptr_arg, size_t length_arg, size_t alloced_length_arg,
             CHARSET_INFO *cs)
  {
    Binary_string::reset(ptr_arg, length_arg, alloced_length_arg);
    set_charset(cs);
  }

  inline String& operator = (const String &s)
  {
    if (&s != this)
    {
      set_charset(s);
      Binary_string::operator=(s);
    }
    return *this;
  }

  bool copy()
  {
    return Binary_string::copy();
  }
  bool copy(const String &s)
  {
    set_charset(s);
    return Binary_string::copy(s);
  }
  bool copy(const char *s, size_t arg_length, CHARSET_INFO *cs)
  {
    set_charset(cs);
    return Binary_string::copy(s, arg_length);
  }
  bool copy_or_move(const char *s, size_t arg_length, CHARSET_INFO *cs)
  {
    set_charset(cs);
    return Binary_string::copy_or_move(s, arg_length);
  }
  static bool needs_conversion(size_t arg_length,
  			       CHARSET_INFO *cs_from, CHARSET_INFO *cs_to,
			       uint32 *offset);
  static bool needs_conversion_on_storage(size_t arg_length,
                                          CHARSET_INFO *cs_from,
                                          CHARSET_INFO *cs_to);
  bool copy_aligned(const char *s, size_t arg_length, size_t offset,
		    CHARSET_INFO *cs);
  bool set_or_copy_aligned(const char *s, size_t arg_length, CHARSET_INFO *cs);
  bool can_be_safely_converted_to(CHARSET_INFO *tocs) const
  {
    if (charset() == &my_charset_bin)
      return Well_formed_prefix(tocs, ptr(), length()).length() == length();
    String try_val;
    uint try_conv_error= 0;
    try_val.copy(ptr(), length(), charset(), tocs, &try_conv_error);
    return try_conv_error == 0;
  }
  bool copy(const char*s, size_t 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);
  }
  bool copy(CHARSET_INFO *tocs,
            CHARSET_INFO *fromcs, const char *src, size_t src_length,
            size_t nchars, String_copier *copier)
  {
    if (unlikely(alloc(tocs->mbmaxlen * src_length)))
      return true;
    str_length= copier->well_formed_copy(tocs, Ptr, alloced_length(),
                                         fromcs, src, (uint)src_length, (uint)nchars);
    set_charset(tocs);
    return false;
  }
  // Append without character set conversion
  bool append(const String &s)
  {
    return Binary_string::append(s);
  }
  inline bool append(char chr)
  {
    return Binary_string::append_char(chr);
  }
  bool append_hex(const char *src, uint32 srclen)
  {
    return Binary_string::append_hex(src, srclen);
  }
  bool append_hex(const uchar *src, uint32 srclen)
  {
    return Binary_string::append_hex((const char*)src, srclen);
  }
  bool append_introducer_and_hex(const String *str)
  {
    return
      append(STRING_WITH_LEN("_"))   ||
      append(str->charset()->csname)  ||
      append(STRING_WITH_LEN(" 0x")) ||
      append_hex(str->ptr(), (uint32) str->length());
  }
  bool append(IO_CACHE* file, uint32 arg_length)
  {
    return Binary_string::append(file, arg_length);
  }
  inline bool append(const char *s, uint32 arg_length, uint32 step_alloc)
  {
    return append_with_step(s, arg_length, step_alloc);
  }

  // Append with optional character set conversion from ASCII (e.g. to UCS2)
  bool append(const char *s)
  {
    return append(s, strlen(s));
  }
  bool append(const LEX_STRING *ls)
  {
    DBUG_ASSERT(ls->length < UINT_MAX32 &&
                ((ls->length == 0 && !ls->str) ||
                 ls->length == strlen(ls->str)));
    return append(ls->str, (uint32) ls->length);
  }
  bool append(const LEX_CSTRING *ls)
  {
    DBUG_ASSERT(ls->length < UINT_MAX32 &&
                ((ls->length == 0 && !ls->str) ||
                 ls->length == strlen(ls->str)));
    return append(ls->str, (uint32) ls->length);
  }
  bool append(const LEX_CSTRING &ls)
  {
    return append(&ls);
  }
  bool append_name_value(const LEX_CSTRING &name,
                         const LEX_CSTRING &value,
                         uchar quot= '\0')
  {
    return
      append(name) ||
      append('=') ||
      (quot && append(quot)) ||
      append(value) ||
      (quot && append(quot));
  }
  bool append(const char *s, size_t size);
  bool append_parenthesized(long nr, int radix= 10);

  // Append with optional character set conversion from cs to charset()
  bool append(const char *s, size_t arg_length, CHARSET_INFO *cs);
  bool append(const LEX_CSTRING &s, CHARSET_INFO *cs)
  {
    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.:
      0x05 -> "(flag04|flag01)"

    @param flags  - the flags to translate
    @param names  - an array of flag names
    @param count  - the number of available elements in "names"
  */
  bool append_flag32_names(uint32 flags, const char *names[], size_t count)
  {
    bool added= false;
    if (flags && append('('))
      return true;
    for (ulong i= 0; i <= 31; i++)
    {
      ulong bit= 31 - i;
      if (flags & (1 << bit))
      {
        if (added && append('|'))
          return true;
        if (append(bit < count ? names[bit] : "?"))
          return true;
        added= true;
      }
    }
    if (flags && append(')'))
      return true;
    return false;
  }

  void strip_sp();
  friend int sortcmp(const String *a,const String *b, CHARSET_INFO *cs);
  friend int stringcmp(const String *a,const String *b);
  friend String *copy_if_not_alloced(String *a,String *b,uint32 arg_length);
  friend class Field;
  uint32 numchars() const
  {
    return (uint32) Charset::numchars(ptr(), end());
  }
  int charpos(longlong i, uint32 offset=0)
  {
    if (i <= 0)
      return (int) i;
    return (int) Charset::charpos(ptr() + offset, end(), (size_t) i);
  }
  size_t lengthsp() const
  {
    return Charset::lengthsp(Ptr, str_length);
  }

  void print(String *to) const;
  void print_with_conversion(String *to, CHARSET_INFO *cs) const;
  void print(String *to, CHARSET_INFO *cs) const
  {
    if (my_charset_same(charset(), cs))
      print(to);
    else
      print_with_conversion(to, cs);
  }

  static my_wc_t escaped_wc_for_single_quote(my_wc_t ch)
  {
    switch (ch)
    {
    case '\\':   return '\\';
    case '\0':   return '0';
    case '\'':   return '\'';
    case '\n':   return 'n';
    case '\r':   return 'r';
    case '\032': return 'Z';
    }
    return 0;
  }

  // Append for single quote using mb_wc/wc_mb Unicode conversion
  bool append_for_single_quote_using_mb_wc(const char *str, size_t length,
                                           CHARSET_INFO *cs);

  // Append for single quote with optional mb_wc/wc_mb conversion
  bool append_for_single_quote_opt_convert(const char *str,
                                           size_t length,
                                           CHARSET_INFO *cs)
  {
    return charset() == &my_charset_bin || cs == &my_charset_bin  ||
           my_charset_same(charset(), cs) ?
           append_for_single_quote(str, length) :
           append_for_single_quote_using_mb_wc(str, length, cs);
  }

  bool append_for_single_quote_opt_convert(const String &str)
  {
    return append_for_single_quote_opt_convert(str.ptr(),
                                               str.length(),
                                               str.charset());
  }

  bool append_for_single_quote(const char *st, size_t len);
  bool append_for_single_quote(const String *s)
  {
    return append_for_single_quote(s->ptr(), s->length());
  }
  bool append_for_single_quote(const char *st)
  {
    size_t len= strlen(st);
    DBUG_ASSERT(len < UINT_MAX32);
    return append_for_single_quote(st, (uint32) len);
  }

  void swap(String &s)
  {
    Charset::swap(s);
    Binary_string::swap(s);
  }

  uint well_formed_length() const
  {
    return (uint) Well_formed_prefix(charset(), ptr(), length()).length();
  }
  bool is_ascii() const
  {
    if (length() == 0)
      return TRUE;
    if (charset()->mbminlen > 1)
      return FALSE;
    return !has_8bit_bytes();
  }
  bool eq(const String *other, CHARSET_INFO *cs) const
  {
    return !sortcmp(this, other, cs);
  }
private:
  bool append_semi_hex(const char *s, uint len, CHARSET_INFO *cs);
};


// The following class is a backport from MySQL 5.6:
/**
  String class wrapper with a preallocated buffer of size buff_sz

  This class allows to replace sequences of:
     char buff[12345];
     String str(buff, sizeof(buff));
     str.length(0);
  with a simple equivalent declaration:
     StringBuffer<12345> str;
*/

template<size_t buff_sz>
class StringBuffer : public String
{
  char buff[buff_sz];

public:
  StringBuffer() : String(buff, buff_sz, &my_charset_bin) { length(0); }
  explicit StringBuffer(CHARSET_INFO *cs) : String(buff, buff_sz, cs)
  {
    length(0);
  }
};


template<size_t buff_sz>
class BinaryStringBuffer : public Binary_string
{
  char buff[buff_sz];
public:
  BinaryStringBuffer() : Binary_string(buff, buff_sz) { length(0); }
};


class String_space: public String
{
public:
  String_space(uint n)
  {
    if (fill(n, ' '))
      set("", 0, &my_charset_bin);
  }
};


static inline bool check_if_only_end_space(CHARSET_INFO *cs,
                                           const char *str,
                                           const char *end)
{
  return str + cs->scan(str, end, MY_SEQ_SPACES) == end;
}

int append_query_string(CHARSET_INFO *csinfo, String *to,
                        const char *str, size_t len, bool no_backslash);

#endif /* SQL_STRING_INCLUDED */