/* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.

 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 02110-1301 USA */

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

#include <my_global.h>
#include <my_sys.h>
#include <m_string.h>
#include <m_ctype.h>
#include <mysql_com.h>

#include "sql_string.h"

#include <algorithm>

using std::min;
using std::max;

/*****************************************************************************
** String functions
*****************************************************************************/

bool String::real_alloc(uint32 length)
{
 uint32 arg_length= ALIGN_SIZE(length + 1);
 DBUG_ASSERT(arg_length > length);
 if (arg_length <= length)
 return TRUE; /* Overflow */
 str_length=0;
 if (Alloced_length < arg_length)
 {
 free();
 if (!(Ptr=(char*) my_malloc(arg_length,MYF(MY_WME))))
 return TRUE;
 Alloced_length=arg_length;
 alloced=1;
 }
 Ptr[0]=0;
 return FALSE;
}


/**
 Allocates a new buffer on the heap for this String.

 - If the String's internal buffer is privately owned and heap allocated,
 one of the following is performed.

 - If the requested length is greater than what fits in the buffer, a new
 buffer is allocated, data moved and the old buffer freed.

 - If the requested length is less or equal to what fits in the buffer, a
 null character is inserted at the appropriate position.

 - If the String does not keep a private buffer on the heap, such a buffer
 will be allocated and the string copied accoring to its length, as found
 in String::length().

 For C compatibility, the new string buffer is null terminated.

 @param alloc_length The requested string size in characters, excluding any
 null terminator.

 @retval false Either the copy operation is complete or, if the size of the
 new buffer is smaller than the currently allocated buffer (if one exists),
 no allocation occured.

 @retval true An error occured when attempting to allocate memory.
*/
bool String::realloc(uint32 alloc_length)
{
 uint32 len=ALIGN_SIZE(alloc_length+1);
 DBUG_ASSERT(len > alloc_length);
 if (len <= alloc_length)
 return TRUE; /* Overflow */
 if (Alloced_length < len)
 {
 char *new_ptr;
 if (alloced)
 {
 if (!(new_ptr= (char*) my_realloc(Ptr,len,MYF(MY_WME))))
 return TRUE;				// Signal error
 }
 else if ((new_ptr= (char*) my_malloc(len,MYF(MY_WME))))
 {
 if (str_length > len - 1)
 str_length= 0;
 if (str_length)				// Avoid bugs in memcpy on AIX
	memcpy(new_ptr,Ptr,str_length);
 new_ptr[str_length]=0;
 alloced=1;
 }
 else
 return TRUE;			// Signal error
 Ptr= new_ptr;
 Alloced_length= len;
 }
 Ptr[alloc_length]=0;			// This make other funcs shorter
 return FALSE;
}

bool String::set_int(longlong num, bool unsigned_flag, const CHARSET_INFO *cs)
{
 uint l=20*cs->mbmaxlen+1;
 int base= unsigned_flag ? 10 : -10;

 if (alloc(l))
 return TRUE;
 str_length=(uint32) (cs->cset->longlong10_to_str)(cs,Ptr,l,base,num);
 str_charset=cs;
 return FALSE;
}

bool String::set_real(double num,uint decimals, const CHARSET_INFO *cs)
{
 char buff[FLOATING_POINT_BUFFER];
 uint dummy_errors;
 size_t len;

 str_charset=cs;
 if (decimals >= NOT_FIXED_DEC)
 {
 len= my_gcvt(num, MY_GCVT_ARG_DOUBLE, sizeof(buff) - 1, buff, NULL);
 return copy(buff, len, &my_charset_latin1, cs, &dummy_errors);
 }
 len= my_fcvt(num, decimals, buff, NULL);
 return copy(buff, (uint32) len, &my_charset_latin1, cs,
 &dummy_errors);
}


bool String::copy()
{
 if (!alloced)
 {
 Alloced_length=0;				// Force realloc
 return realloc(str_length);
 }
 return FALSE;
}

/**
 Copies the internal buffer from str. If this String has a private heap
 allocated buffer where new data does not fit, a new buffer is allocated
 before copying and the old buffer freed. Character set information is also
 copied.

 @param str The string whose internal buffer is to be copied.

 @retval false Success.
 @retval true Memory allocation failed.
*/
bool String::copy(const String &str)
{
 if (alloc(str.str_length))
 return TRUE;
 str_length=str.str_length;
 bmove(Ptr,str.Ptr,str_length);		// May be overlapping
 Ptr[str_length]=0;
 str_charset=str.str_charset;
 return FALSE;
}

bool String::copy(const char *str,uint32 arg_length,
 const CHARSET_INFO *cs)
{
 if (alloc(arg_length))
 return TRUE;
 if ((str_length=arg_length))
 memcpy(Ptr,str,arg_length);
 Ptr[arg_length]=0;
 str_charset=cs;
 return FALSE;
}


/*
 Checks that the source string can be just copied to the destination string
 without conversion.

 SYNPOSIS

 needs_conversion()
 arg_length		Length of string to copy.
 from_cs		Character set to copy from
 to_cs			Character set to copy to
 uint32 *offset	Returns number of unaligned characters.

 RETURN
 0 No conversion needed
 1 Either character set conversion or adding leading zeros
 (e.g. for UCS-2) must be done

 NOTE
 to_cs may be NULL for "no conversion" if the system variable
 character_set_results is NULL.
*/

bool String::needs_conversion(uint32 arg_length,
			 const CHARSET_INFO *from_cs,
			 const CHARSET_INFO *to_cs,
			 uint32 *offset)
{
 *offset= 0;
 if (!to_cs ||
 (to_cs == &my_charset_bin) || 
 (to_cs == from_cs) ||
 my_charset_same(from_cs, to_cs) ||
 ((from_cs == &my_charset_bin) &&
 (!(*offset=(arg_length % to_cs->mbminlen)))))
 return FALSE;
 return TRUE;
}


/*
 Checks that the source string can just be copied to the destination string
 without conversion.
 Unlike needs_conversion it will require conversion on incoming binary data
 to ensure the data are verified for vailidity first.

 @param arg_length Length of string to copy.
 @param from_cs Character set to copy from
 @param to_cs Character set to copy to

 @return conversion needed
*/
bool String::needs_conversion_on_storage(uint32 arg_length,
 const CHARSET_INFO *cs_from,
 const CHARSET_INFO *cs_to)
{
 uint32 offset;
 return (needs_conversion(arg_length, cs_from, cs_to, &offset) ||
 /* force conversion when storing a binary string */
 (cs_from == &my_charset_bin &&
 /* into a non-binary destination */
 cs_to != &my_charset_bin &&
 /* and any of the following is true :*/
 (
 /* it's a variable length encoding */
 cs_to->mbminlen != cs_to->mbmaxlen ||
 /* longer than 2 bytes : neither 1 byte nor ucs2 */
 cs_to->mbminlen > 2 ||
 /* and is not a multiple of the char byte size */
 0 != (arg_length % cs_to->mbmaxlen)
 )
 )
 );
}


/*
 Copy a multi-byte character sets with adding leading zeros.

 SYNOPSIS

 copy_aligned()
 str			String to copy
 arg_length		Length of string. This should NOT be dividable with
			cs->mbminlen.
 offset		arg_length % cs->mb_minlength
 cs			Character set for 'str'

 NOTES
 For real multi-byte, ascii incompatible charactser sets,
 like UCS-2, add leading zeros if we have an incomplete character.
 Thus, 
 SELECT _ucs2 0xAA 
 will automatically be converted into
 SELECT _ucs2 0x00AA

 RETURN
 0 ok
 1 error
*/

bool String::copy_aligned(const char *str,uint32 arg_length, uint32 offset,
			 const CHARSET_INFO *cs)
{
 /* How many bytes are in incomplete character */
 offset= cs->mbminlen - offset; /* How many zeros we should prepend */
 DBUG_ASSERT(offset && offset != cs->mbminlen);

 uint32 aligned_length= arg_length + offset;
 if (alloc(aligned_length))
 return TRUE;
 
 /*
 Note, this is only safe for big-endian UCS-2.
 If we add little-endian UCS-2 sometimes, this code
 will be more complicated. But it's OK for now.
 */
 memset(Ptr, 0, offset);
 memcpy(Ptr + offset, str, arg_length);
 Ptr[aligned_length]=0;
 /* str_length is always >= 0 as arg_length is != 0 */
 str_length= aligned_length;
 str_charset= cs;
 return FALSE;
}


bool String::set_or_copy_aligned(const char *str,uint32 arg_length,
				 const CHARSET_INFO *cs)
{
 /* How many bytes are in incomplete character */
 uint32 offset= (arg_length % cs->mbminlen); 
 
 if (!offset) /* All characters are complete, just copy */
 {
 set(str, arg_length, cs);
 return FALSE;
 }
 return copy_aligned(str, arg_length, offset, cs);
}


/**
 Copies the character data into this String, with optional character set
 conversion.

 @return
 FALSE ok
 TRUE Could not allocate result buffer

*/

bool String::copy(const char *str, uint32 arg_length,
		 const CHARSET_INFO *from_cs, const CHARSET_INFO *to_cs, uint *errors)
{
 uint32 offset;

 DBUG_ASSERT(!str || str != Ptr);
 
 if (!needs_conversion(arg_length, from_cs, to_cs, &offset))
 {
 *errors= 0;
 return copy(str, arg_length, to_cs);
 }
 if ((from_cs == &my_charset_bin) && offset)
 {
 *errors= 0;
 return copy_aligned(str, arg_length, offset, to_cs);
 }
 uint32 new_length= to_cs->mbmaxlen*arg_length;
 if (alloc(new_length))
 return TRUE;
 str_length=copy_and_convert((char*) Ptr, new_length, to_cs,
 str, arg_length, from_cs, errors);
 str_charset=to_cs;
 return FALSE;
}


/*
 Set a string to the value of a latin1-string, keeping the original charset

 SYNOPSIS
 copy_or_set()
 str			String of a simple charset (latin1)
 arg_length		Length of string

 IMPLEMENTATION
 If string object is of a simple character set, set it to point to the
 given string.
 If not, make a copy and convert it to the new character set.

 RETURN
 0	ok
 1	Could not allocate result buffer

*/

bool String::set_ascii(const char *str, uint32 arg_length)
{
 if (str_charset->mbminlen == 1)
 {
 set(str, arg_length, str_charset);
 return 0;
 }
 uint dummy_errors;
 return copy(str, arg_length, &my_charset_latin1, str_charset, &dummy_errors);
}


/* This is used by mysql.cc */

bool String::fill(uint32 max_length,char fill_char)
{
 if (str_length > max_length)
 Ptr[str_length=max_length]=0;
 else
 {
 if (realloc(max_length))
 return TRUE;
 memset(Ptr+str_length, fill_char, max_length-str_length);
 str_length=max_length;
 }
 return FALSE;
}

void String::strip_sp()
{
 while (str_length && my_isspace(str_charset,Ptr[str_length-1]))
 str_length--;
}

bool String::append(const String &s)
{
 if (s.length())
 {
 if (realloc(str_length+s.length()))
 return TRUE;
 memcpy(Ptr+str_length,s.ptr(),s.length());
 str_length+=s.length();
 }
 return FALSE;
}


/*
 Append an ASCII string to the a string of the current character set
*/

bool String::append(const char *s,uint32 arg_length)
{
 if (!arg_length)
 return FALSE;

 /*
 For an ASCII incompatible string, e.g. UCS-2, we need to convert
 */
 if (str_charset->mbminlen > 1)
 {
 uint32 add_length=arg_length * str_charset->mbmaxlen;
 uint dummy_errors;
 if (realloc(str_length+ add_length))
 return TRUE;
 str_length+= copy_and_convert(Ptr+str_length, add_length, str_charset,
				 s, arg_length, &my_charset_latin1,
 &dummy_errors);
 return FALSE;
 }

 /*
 For an ASCII compatinble string we can just append.
 */
 if (realloc(str_length+arg_length))
 return TRUE;
 memcpy(Ptr+str_length,s,arg_length);
 str_length+=arg_length;
 return FALSE;
}


/*
 Append a 0-terminated ASCII string
*/

bool String::append(const char *s)
{
 return append(s, (uint) strlen(s));
}



bool String::append_ulonglong(ulonglong val)
{
 if (realloc(str_length+MAX_BIGINT_WIDTH+2))
 return TRUE;
 char *end= (char*) longlong10_to_str(val, (char*) Ptr + str_length, 10);
 str_length= end - Ptr;
 return FALSE;
}

/*
 Append a string in the given charset to the string
 with character set recoding
*/

bool String::append(const char *s,uint32 arg_length, const CHARSET_INFO *cs)
{
 uint32 offset;
 
 if (needs_conversion(arg_length, cs, str_charset, &offset))
 {
 uint32 add_length;
 if ((cs == &my_charset_bin) && offset)
 {
 DBUG_ASSERT(str_charset->mbminlen > offset);
 offset= str_charset->mbminlen - offset; // How many characters to pad
 add_length= arg_length + offset;
 if (realloc(str_length + add_length))
 return TRUE;
 memset(Ptr + str_length, 0, offset);
 memcpy(Ptr + str_length + offset, s, arg_length);
 str_length+= add_length;
 return FALSE;
 }

 add_length= arg_length / cs->mbminlen * str_charset->mbmaxlen;
 uint dummy_errors;
 if (realloc(str_length + add_length)) 
 return TRUE;
 str_length+= copy_and_convert(Ptr+str_length, add_length, str_charset,
				 s, arg_length, cs, &dummy_errors);
 }
 else
 {
 if (realloc(str_length + arg_length)) 
 return TRUE;
 memcpy(Ptr + str_length, s, arg_length);
 str_length+= arg_length;
 }
 return FALSE;
}

bool String::append(IO_CACHE* file, uint32 arg_length)
{
 if (realloc(str_length+arg_length))
 return TRUE;
 if (my_b_read(file, (uchar*) Ptr + str_length, arg_length))
 {
 shrink(str_length);
 return TRUE;
 }
 str_length+=arg_length;
 return FALSE;
}


/**
 Append a parenthesized number to String.
 Used in various pieces of SHOW related code.

 @param nr Number
 @param radix Radix, optional parameter, 10 by default.
*/
bool String::append_parenthesized(long nr, int radix)
{
 char buff[64], *end;
 buff[0]= '(';
 end= int10_to_str(nr, buff + 1, radix);
 *end++ = ')';
 return append(buff, (uint) (end - buff));
}


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(str_length + t_length))
 return TRUE;
 t_length= full_length - arg_length;
 if (t_length > 0)
 {
 memset(Ptr+str_length, fill_char, t_length);
 str_length=str_length + t_length;
 }
 append(s, arg_length);
 return FALSE;
}

uint32 String::numchars() const
{
 return str_charset->cset->numchars(str_charset, Ptr, Ptr+str_length);
}

int String::charpos(int i,uint32 offset)
{
 if (i <= 0)
 return i;
 return str_charset->cset->charpos(str_charset,Ptr+offset,Ptr+str_length,i);
}

int String::strstr(const String &s,uint32 offset)
{
 if (s.length()+offset <= str_length)
 {
 if (!s.length())
 return ((int) offset);	// Empty string is always found

 register const char *str = Ptr+offset;
 register const char *search=s.ptr();
 const char *end=Ptr+str_length-s.length()+1;
 const char *search_end=s.ptr()+s.length();
skip:
 while (str != end)
 {
 if (*str++ == *search)
 {
	register char *i,*j;
	i=(char*) str; j=(char*) search+1;
	while (j != search_end)
	 if (*i++ != *j++) goto skip;
	return (int) (str-Ptr) -1;
 }
 }
 }
 return -1;
}

/*
** Search string from end. Offset is offset to the end of string
*/

int String::strrstr(const String &s,uint32 offset)
{
 if (s.length() <= offset && offset <= str_length)
 {
 if (!s.length())
 return offset;				// Empty string is always found
 register const char *str = Ptr+offset-1;
 register const char *search=s.ptr()+s.length()-1;

 const char *end=Ptr+s.length()-2;
 const char *search_end=s.ptr()-1;
skip:
 while (str != end)
 {
 if (*str-- == *search)
 {
	register char *i,*j;
	i=(char*) str; j=(char*) search-1;
	while (j != search_end)
	 if (*i-- != *j--) goto skip;
	return (int) (i-Ptr) +1;
 }
 }
 }
 return -1;
}

/*
 Replace substring with string
 If wrong parameter or not enough memory, do nothing
*/

bool String::replace(uint32 offset,uint32 arg_length,const String &to)
{
 return replace(offset,arg_length,to.ptr(),to.length());
}

bool String::replace(uint32 offset,uint32 arg_length,
 const char *to, uint32 to_length)
{
 long diff = (long) to_length-(long) arg_length;
 if (offset+arg_length <= str_length)
 {
 if (diff < 0)
 {
 if (to_length)
	memcpy(Ptr+offset,to,to_length);
 bmove(Ptr+offset+to_length,Ptr+offset+arg_length,
	 str_length-offset-arg_length);
 }
 else
 {
 if (diff)
 {
	if (realloc(str_length+(uint32) diff))
	 return TRUE;
	bmove_upp((uchar*) Ptr+str_length+diff, (uchar*) Ptr+str_length,
		 str_length-offset-arg_length);
 }
 if (to_length)
	memcpy(Ptr+offset,to,to_length);
 }
 str_length+=(uint32) diff;
 }
 return FALSE;
}


// added by Holyfoot for "geometry" needs
int String::reserve(uint32 space_needed, uint32 grow_by)
{
 if (Alloced_length < str_length + space_needed)
 {
 if (realloc(Alloced_length + max(space_needed, grow_by) - 1))
 return TRUE;
 }
 return FALSE;
}

void String::qs_append(const char *str, uint32 len)
{
 memcpy(Ptr + str_length, str, len + 1);
 str_length += len;
}

void String::qs_append(double d)
{
 char *buff = Ptr + str_length;
 str_length+= my_gcvt(d, MY_GCVT_ARG_DOUBLE, FLOATING_POINT_BUFFER - 1, buff,
 NULL);
}

void String::qs_append(double *d)
{
 double ld;
 float8get(ld, (char*) d);
 qs_append(ld);
}

void String::qs_append(int i)
{
 char *buff= Ptr + str_length;
 char *end= int10_to_str(i, buff, -10);
 str_length+= (int) (end-buff);
}

void String::qs_append(uint i)
{
 char *buff= Ptr + str_length;
 char *end= int10_to_str(i, buff, 10);
 str_length+= (int) (end-buff);
}

/*
 Compare strings according to collation, without end space.

 SYNOPSIS
 sortcmp()
 s		First string
 t		Second string
 cs		Collation

 NOTE:
 Normally this is case sensitive comparison

 RETURN
 < 0	s < t
 0	s == t
 > 0	s > t
*/


int sortcmp(const String *s,const String *t, const CHARSET_INFO *cs)
{
 return cs->coll->strnncollsp(cs,
 (uchar *) s->ptr(),s->length(),
 (uchar *) t->ptr(),t->length(), 0);
}


/*
 Compare strings byte by byte. End spaces are also compared.

 SYNOPSIS
 stringcmp()
 s		First string
 t		Second string

 NOTE:
 Strings are compared as a stream of uchars

 RETURN
 < 0	s < t
 0	s == t
 > 0	s > t
*/


int stringcmp(const String *s,const String *t)
{
 uint32 s_len=s->length(),t_len=t->length(),len=min(s_len,t_len);
 int cmp= memcmp(s->ptr(), t->ptr(), len);
 return (cmp) ? cmp : (int) (s_len - t_len);
}


String *copy_if_not_alloced(String *to,String *from,uint32 from_length)
{
 if (from->Alloced_length >= from_length)
 return from;
 if ((from->alloced && (from->Alloced_length != 0)) || !to || from == to)
 {
 (void) from->realloc(from_length);
 return from;
 }
 if (to->realloc(from_length))
 return from;				// Actually an error
 if ((to->str_length=min(from->str_length,from_length)))
 memcpy(to->Ptr,from->Ptr,to->str_length);
 to->str_charset=from->str_charset;
 return to;
}


/****************************************************************************
 Help functions
****************************************************************************/

/**
 Copy string with HEX-encoding of "bad" characters.

 @details This functions copies the string pointed by "src"
 to the string pointed by "dst". Not more than "srclen" bytes
 are read from "src". Any sequences of bytes representing
 a not-well-formed substring (according to cs) are hex-encoded,
 and all well-formed substrings (according to cs) are copied as is.
 Not more than "dstlen" bytes are written to "dst". The number 
 of bytes written to "dst" is returned.

 @param cs character set pointer of the destination string
 @param[out] dst destination string
 @param dstlen size of dst
 @param src source string
 @param srclen length of src

 @retval result length
*/

size_t
my_copy_with_hex_escaping(const CHARSET_INFO *cs,
 char *dst, size_t dstlen,
 const char *src, size_t srclen)
{
 const char *srcend= src + srclen;
 char *dst0= dst;

 for ( ; src < srcend ; )
 {
 size_t chlen;
 if ((chlen= my_ismbchar(cs, src, srcend)))
 {
 if (dstlen < chlen)
 break; /* purecov: inspected */
 memcpy(dst, src, chlen);
 src+= chlen;
 dst+= chlen;
 dstlen-= chlen;
 }
 else if (*src & 0x80)
 {
 if (dstlen < 4)
 break; /* purecov: inspected */
 *dst++= '\\';
 *dst++= 'x';
 *dst++= _dig_vec_upper[((unsigned char) *src) >> 4];
 *dst++= _dig_vec_upper[((unsigned char) *src) & 15];
 src++;
 dstlen-= 4;
 }
 else
 {
 if (dstlen < 1)
 break; /* purecov: inspected */
 *dst++= *src++;
 dstlen--;
 }
 }
 return dst - dst0;
}

/*
 copy a string,
 with optional character set conversion,
 with optional left padding (for binary -> UCS2 conversion)

 SYNOPSIS
 well_formed_copy_nchars()
 to			 Store result here
 to_length Maxinum length of "to" string
 to_cs		 Character set of "to" string
 from		 Copy from here
 from_length		 Length of from string
 from_cs		 From character set
 nchars Copy not more that nchars characters
 well_formed_error_pos Return position when "from" is not well formed
 or NULL otherwise.
 cannot_convert_error_pos Return position where a not convertable
 character met, or NULL otherwise.
 from_end_pos Return position where scanning of "from"
 string stopped.
 NOTES

 RETURN
 length of bytes copied to 'to'
*/


uint32
well_formed_copy_nchars(const CHARSET_INFO *to_cs,
 char *to, uint to_length,
 const CHARSET_INFO *from_cs,
 const char *from, uint from_length,
 uint nchars,
 const char **well_formed_error_pos,
 const char **cannot_convert_error_pos,
 const char **from_end_pos)
{
 uint res;

 if ((to_cs == &my_charset_bin) || 
 (from_cs == &my_charset_bin) ||
 (to_cs == from_cs) ||
 my_charset_same(from_cs, to_cs))
 {
 if (to_length < to_cs->mbminlen || !nchars)
 {
 *from_end_pos= from;
 *cannot_convert_error_pos= NULL;
 *well_formed_error_pos= NULL;
 return 0;
 }

 if (to_cs == &my_charset_bin)
 {
 res= min(min(nchars, to_length), from_length);
 memmove(to, from, res);
 *from_end_pos= from + res;
 *well_formed_error_pos= NULL;
 *cannot_convert_error_pos= NULL;
 }
 else
 {
 int well_formed_error;
 uint from_offset;

 if ((from_offset= (from_length % to_cs->mbminlen)) &&
 (from_cs == &my_charset_bin))
 {
 /*
 Copying from BINARY to UCS2 needs to prepend zeros sometimes:
 INSERT INTO t1 (ucs2_column) VALUES (0x01);
 0x01 -> 0x0001
 */
 uint pad_length= to_cs->mbminlen - from_offset;
 memset(to, 0, pad_length);
 memmove(to + pad_length, from, from_offset);
 /*
 In some cases left zero-padding can create an incorrect character.
 For example:
 INSERT INTO t1 (utf32_column) VALUES (0x110000);
 We'll pad the value to 0x00110000, which is a wrong UTF32 sequence!
 The valid characters range is limited to 0x00000000..0x0010FFFF.

 Make sure we didn't pad to an incorrect character.
 */
 if (to_cs->cset->well_formed_len(to_cs,
 to, to + to_cs->mbminlen, 1,
 &well_formed_error) !=
 to_cs->mbminlen)
 {
 *from_end_pos= *well_formed_error_pos= from;
 *cannot_convert_error_pos= NULL;
 return 0;
 }
 nchars--;
 from+= from_offset;
 from_length-= from_offset;
 to+= to_cs->mbminlen;
 to_length-= to_cs->mbminlen;
 }

 set_if_smaller(from_length, to_length);
 res= to_cs->cset->well_formed_len(to_cs, from, from + from_length,
 nchars, &well_formed_error);
 memmove(to, from, res);
 *from_end_pos= from + res;
 *well_formed_error_pos= well_formed_error ? from + res : NULL;
 *cannot_convert_error_pos= NULL;
 if (from_offset)
 res+= to_cs->mbminlen;
 }
 }
 else
 {
 int cnvres;
 my_wc_t wc;
 my_charset_conv_mb_wc mb_wc= from_cs->cset->mb_wc;
 my_charset_conv_wc_mb wc_mb= to_cs->cset->wc_mb;
 const uchar *from_end= (const uchar*) from + from_length;
 uchar *to_end= (uchar*) to + to_length;
 char *to_start= to;
 *well_formed_error_pos= NULL;
 *cannot_convert_error_pos= NULL;

 for ( ; nchars; nchars--)
 {
 const char *from_prev= from;
 if ((cnvres= (*mb_wc)(from_cs, &wc, (uchar*) from, from_end)) > 0)
 from+= cnvres;
 else if (cnvres == MY_CS_ILSEQ)
 {
 if (!*well_formed_error_pos)
 *well_formed_error_pos= from;
 from++;
 wc= '?';
 }
 else if (cnvres > MY_CS_TOOSMALL)
 {
 /*
 A correct multibyte sequence detected
 But it doesn't have Unicode mapping.
 */
 if (!*cannot_convert_error_pos)
 *cannot_convert_error_pos= from;
 from+= (-cnvres);
 wc= '?';
 }
 else
 break; // Not enough characters

outp:
 if ((cnvres= (*wc_mb)(to_cs, wc, (uchar*) to, to_end)) > 0)
 to+= cnvres;
 else if (cnvres == MY_CS_ILUNI && wc != '?')
 {
 if (!*cannot_convert_error_pos)
 *cannot_convert_error_pos= from_prev;
 wc= '?';
 goto outp;
 }
 else
 {
 from= from_prev;
 break;
 }
 }
 *from_end_pos= from;
 res= (uint) (to - to_start);
 }
 return (uint32) res;
}




void String::print(String *str)
{
 char *st= (char*)Ptr, *end= st+str_length;
 for (; st < end; st++)
 {
 uchar c= *st;
 switch (c)
 {
 case '\\':
 str->append(STRING_WITH_LEN("\\\\"));
 break;
 case '0円':
 str->append(STRING_WITH_LEN("\\0"));
 break;
 case '\'':
 str->append(STRING_WITH_LEN("\\'"));
 break;
 case '\n':
 str->append(STRING_WITH_LEN("\\n"));
 break;
 case '\r':
 str->append(STRING_WITH_LEN("\\r"));
 break;
 case '032円': // Ctrl-Z
 str->append(STRING_WITH_LEN("\\Z"));
 break;
 default:
 str->append(c);
 }
 }
}


/*
 Exchange state of this object and argument.

 SYNOPSIS
 String::swap()

 RETURN
 Target string will contain state of this object and vice versa.
*/

void String::swap(String &s)
{
 swap_variables(char *, Ptr, s.Ptr);
 swap_variables(uint32, str_length, s.str_length);
 swap_variables(uint32, Alloced_length, s.Alloced_length);
 swap_variables(bool, alloced, s.alloced);
 swap_variables(const CHARSET_INFO *, str_charset, s.str_charset);
}


/**
 Convert string to printable ASCII string

 @details This function converts input string "from" replacing non-ASCII bytes
 with hexadecimal sequences ("\xXX") optionally appending "..." to the end of
 the resulting string.
 This function used in the ER_TRUNCATED_WRONG_VALUE_FOR_FIELD error messages,
 e.g. when a string cannot be converted to a result charset.


 @param to output buffer
 @param to_len size of the output buffer (8 bytes or greater)
 @param from input string
 @param from_len size of the input string
 @param from_cs input charset
 @param nbytes maximal number of bytes to convert (from_len if 0)

 @return number of bytes in the output string
*/

uint convert_to_printable(char *to, size_t to_len,
 const char *from, size_t from_len,
 const CHARSET_INFO *from_cs, size_t nbytes /*= 0*/)
{
 /* needs at least 8 bytes for '\xXX...' and zero byte */
 DBUG_ASSERT(to_len >= 8);

 char *t= to;
 char *t_end= to + to_len - 1; // '- 1' is for the '0円' at the end
 const char *f= from;
 const char *f_end= from + (nbytes ? min(from_len, nbytes) : from_len);
 char *dots= to; // last safe place to append '...'

 if (!f || t == t_end)
 return 0;

 for (; t < t_end && f < f_end; f++)
 {
 /*
 If the source string is ASCII compatible (mbminlen==1)
 and the source character is in ASCII printable range (0x20..0x7F),
 then display the character as is.

 Otherwise, if the source string is not ASCII compatible (e.g. UCS2),
 or the source character is not in the printable range,
 then print the character using HEX notation.
 */
 if (((unsigned char) *f) >= 0x20 &&
 ((unsigned char) *f) <= 0x7F &&
 from_cs->mbminlen == 1)
 {
 *t++= *f;
 }
 else
 {
 if (t_end - t < 4) // \xXX
 break;
 *t++= '\\';
 *t++= 'x';
 *t++= _dig_vec_upper[((unsigned char) *f) >> 4];
 *t++= _dig_vec_upper[((unsigned char) *f) & 0x0F];
 }
 if (t_end - t >= 3) // '...'
 dots= t;
 }
 if (f < from + from_len)
 memcpy(dots, STRING_WITH_LEN("...0円"));
 else
 *t= '0円';
 return t - to;
}