src/port/strtol.c

   1 /*
   2  * $PostgreSQL:$
   3  *
   4  *
   5  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
   6  * Portions Copyright (c) 1990 The Regents of the University of California.
   7  * All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *        notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *        notice, this list of conditions and the following disclaimer in the
  16  *        documentation and/or other materials provided with the distribution.
  17  * 3. Neither the name of the University nor the names of its contributors
  18  *        may be used to endorse or promote products derived from this software
  19  *        without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.      IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #if defined(LIBC_SCCS) && !defined(lint)
  35 static char sccsid[] = "@(#)strtol.c    5.4 (Berkeley) 2/23/91";
  36 #endif   /* LIBC_SCCS and not lint */
  37
  38 #include "c.h"
  39
  40 #include <limits.h>
  41 #include <ctype.h>
  42
  43
  44 #define const
  45
  46 /*
  47  *      Usage Tip:
  48  *
  49  *      strtol() doesn't give a unique return value to indicate that errno
  50  *      should be consulted, so in most cases it is best to set errno = 0
  51  *      before calling this function, and then errno != 0 can be tested
  52  *      after the function completes.
  53  */
  54
  55 /*
  56  * Convert a string to a long integer.
  57  *
  58  * Ignores `locale' stuff.  Assumes that the upper and lower case
  59  * alphabets and digits are each contiguous.
  60  */
  61 long
  62 strtol(nptr, endptr, base)
  63 const char *nptr;
  64 char      **endptr;
  65 int                     base;
  66 {
  67         const char *s = nptr;
  68         unsigned long acc;
  69         unsigned char c;
  70         unsigned long cutoff;
  71         int                     neg = 0,
  72                                 any,
  73                                 cutlim;
  74
  75         /*
  76          * Skip white space and pick up leading +/- sign if any. If base is 0,
  77          * allow 0x for hex and 0 for octal, else assume decimal; if base is
  78          * already 16, allow 0x.
  79          */
  80         do
  81         {
  82                 c = *s++;
  83         } while (isspace(c));
  84         if (c == '-')
  85         {
  86                 neg = 1;
  87                 c = *s++;
  88         }
  89         else if (c == '+')
  90                 c = *s++;
  91         if ((base == 0 || base == 16) &&
  92                 c == '0' && (*s == 'x' || *s == 'X'))
  93         {
  94                 c = s[1];
  95                 s += 2;
  96                 base = 16;
  97         }
  98         if (base == 0)
  99                 base = c == '0' ? 8 : 10;
 100
 101         /*
 102          * Compute the cutoff value between legal numbers and illegal numbers.
 103          * That is the largest legal value, divided by the base.  An input number
 104          * that is greater than this value, if followed by a legal input
 105          * character, is too big.  One that is equal to this value may be valid or
 106          * not; the limit between valid and invalid numbers is then based on the
 107          * last digit.  For instance, if the range for longs is
 108          * [-2147483648..2147483647] and the input base is 10, cutoff will be set
 109          * to 214748364 and cutlim to either 7 (neg==0) or 8 (neg==1), meaning
 110          * that if we have accumulated a value > 214748364, or equal but the next
 111          * digit is > 7 (or 8), the number is too big, and we will return a range
 112          * error.
 113          *
 114          * Set any if any `digits' consumed; make it negative to indicate
 115          * overflow.
 116          */
 117         cutoff = neg ? -(unsigned long) LONG_MIN : LONG_MAX;
 118         cutlim = cutoff % (unsigned long) base;
 119         cutoff /= (unsigned long) base;
 120         for (acc = 0, any = 0;; c = *s++)
 121         {
 122                 if (isdigit(c))
 123                         c -= '0';
 124                 else if (isalpha(c))
 125                         c -= isupper(c) ? 'A' - 10 : 'a' - 10;
 126                 else
 127                         break;
 128                 if ((int) c >= base)
 129                         break;
 130                 if (any < 0 || acc > cutoff || acc == cutoff && (int) c > cutlim)
 131                         any = -1;
 132                 else
 133                 {
 134                         any = 1;
 135                         acc *= base;
 136                         acc += c;
 137                 }
 138         }
 139         if (any < 0)
 140         {
 141                 acc = neg ? LONG_MIN : LONG_MAX;
 142                 errno = ERANGE;
 143         }
 144         else if (neg)
 145                 acc = -acc;
 146         if (endptr != 0)
 147                 *endptr = any ? s - 1 : (char *) nptr;
 148         return acc;
 149 }