text: /* 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 */
  
  /*
    str2int(src, radix, lower, upper, &val)
    converts the string pointed to by src to an integer and stores it in
    val.	It skips leading spaces and tabs (but not newlines, formfeeds,
    backspaces), then it accepts an optional sign and a sequence of digits
    in the specified radix.  The result should satisfy lower <= *val <= upper.
    The result is a pointer to the first character after the number;
    trailing spaces will NOT be skipped.
  
    If an error is detected, the result will be NullS, the value put
    in val will be 0, and errno will be set to
  	EDOM	if there are no digits
  	ERANGE	if the result would overflow or otherwise fail to lie
  		within the specified bounds.
    Check that the bounds are right for your machine.
    This looks amazingly complicated for what you probably thought was an
    easy task.  Coping with integer overflow and the asymmetric range of
    twos complement machines is anything but easy.
  
    So that users of atoi and atol can check whether an error occured,
    I have taken a wholly unprecedented step: errno is CLEARED if this
    call has no problems.
  */
  
  #include <my_global.h>
  #include "m_string.h"
  #include "m_ctype.h"
  #include "my_sys.h"			/* defines errno */
  #include <errno.h>
  
  #define char_val(X) (X >= '0' && X <= '9' ? X-'0' :\
  		     X >= 'A' && X <= 'Z' ? X-'A'+10 :\
  		     X >= 'a' && X <= 'z' ? X-'a'+10 :\
  		     '\177')
  
  char *str2int(const char *src, int radix, long int lower,
  	      long int upper, long int *val)
  {
    int sign;			/* is number negative (+1) or positive (-1) */
    int n;			/* number of digits yet to be converted */
    long limit;			/* "largest" possible valid input */
    long scale;			/* the amount to multiply next digit by */
    long sofar;			/* the running value */
    int d;		/* (negative of) next digit */
    char *start;
    int digits[32];		/* Room for numbers */
  
    /*  Make sure *val is sensible in case of error  */
  
    *val = 0;
  
    /*  Check that the radix is in the range 2..36  */
  
  #ifndef DBUG_OFF
    if (radix < 2 || radix > 36) {
      errno=EDOM;
      return NullS;
    }
  #endif
  
    /*  The basic problem is: how do we handle the conversion of
        a number without resorting to machine-specific code to
        check for overflow?  Obviously, we have to ensure that
        no calculation can overflow.  We are guaranteed that the
        "lower" and "upper" arguments are valid machine integers.
        On sign-and-magnitude, twos-complement, and ones-complement
        machines all, if +|n| is representable, so is -|n|, but on
        twos complement machines the converse is not true.  So the
        "maximum" representable number has a negative representative.
        Limit is set to min(-|lower|,-|upper|); this is the "largest"
        number we are concerned with.	*/
  
    /*  Calculate Limit using Scale as a scratch variable  */
  
    if ((limit = lower) > 0) limit = -limit;
    if ((scale = upper) > 0) scale = -scale;
    if (scale < limit) limit = scale;
  
    /*  Skip leading spaces and check for a sign.
        Note: because on a 2s complement machine MinLong is a valid
        integer but |MinLong| is not, we have to keep the current
        converted value (and the scale!) as *negative* numbers,
        so the sign is the opposite of what you might expect.
        */
    while (my_isspace(&my_charset_latin1,*src)) src++;
    sign = -1;
    if (*src == '+') src++; else
      if (*src == '-') src++, sign = 1;
  
    /*  Skip leading zeros so that we never compute a power of radix
        in scale that we won't have a need for.  Otherwise sticking
        enough 0s in front of a number could cause the multiplication
        to overflow when it neededn't.
        */
    start=(char*) src;
    while (*src == '0') src++;
  
    /*  Move over the remaining digits.  We have to convert from left
        to left in order to avoid overflow.  Answer is after last digit.
        */
  
    for (n = 0; (digits[n]=char_val(*src)) < radix && n < 20; n++,src++) ;
  
    /*  Check that there is at least one digit  */
  
    if (start == src) {
      errno=EDOM;
      return NullS;
    }
  
    /*  The invariant we want to maintain is that src is just
        to the right of n digits, we've converted k digits to
        sofar, scale = -radix**k, and scale < sofar < 0.	Now
        if the final number is to be within the original
        Limit, we must have (to the left)*scale+sofar >= Limit,
        or (to the left)*scale >= Limit-sofar, i.e. the digits
        to the left of src must form an integer <= (Limit-sofar)/(scale).
        In particular, this is true of the next digit.  In our
        incremental calculation of Limit,
  
        IT IS VITAL that (-|N|)/(-|D|) = |N|/|D|
        */
  
    for (sofar = 0, scale = -1; --n >= 1;)
    {
      if ((long) -(d=digits[n]) < limit) {
        errno=ERANGE;
        return NullS;
      }
      limit = (limit+d)/radix, sofar += d*scale; scale *= radix;
    }
    if (n == 0)
    {
      if ((long) -(d=digits[n]) < limit)		/* get last digit */
      {
        errno=ERANGE;
        return NullS;
      }
      sofar+=d*scale;
    }
  
    /*  Now it might still happen that sofar = -32768 or its equivalent,
        so we can't just multiply by the sign and check that the result
        is in the range lower..upper.  All of this caution is a right
        pain in the neck.  If only there were a standard routine which
        says generate thus and such a signal on integer overflow...
        But not enough machines can do it *SIGH*.
        */
    if (sign < 0)
    {
      if (sofar < -LONG_MAX || (sofar= -sofar) > upper)
      {
        errno=ERANGE;
        return NullS;
      }
    }
    else if (sofar < lower)
    {
      errno=ERANGE;
      return NullS;
    }
    *val = sofar;
    errno=0;			/* indicate that all went well */
    return (char*) src;
  }
  