1 files changed, 202 insertions, 0 deletions
diff --git a/strings/str2int.c b/strings/str2int.c
new file mode 100644
index 00000000000..55fcd56adb9
--- /dev/null
+++ b/strings/str2int.c
@@ -0,0 +1,202 @@
+/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
+   
+   This library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public
+   License as published by the Free Software Foundation; either
+   version 2 of the License, or (at your option) any later version.
+   
+   This library 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
+   Library General Public License for more details.
+   
+   You should have received a copy of the GNU Library General Public
+   License along with this library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+   MA 02111-1307, 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 <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(register const char *src, register 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 */
+  register 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 (isspace(*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;
+}
+
+	/* Theese are so slow compared with ordinary, optimized atoi */
+
+#ifdef WANT_OUR_ATOI
+
+int atoi(const char *src)
+{
+  long val;
+  str2int(src, 10, (long) INT_MIN, (long) INT_MAX, &val);
+  return (int) val;
+}
+
+
+long atol(const char *src)
+{
+  long val;
+  str2int(src, 10, LONG_MIN, LONG_MAX, &val);
+  return val;
+}
+
+#endif /* WANT_OUR_ATOI */