Python/mystrtoul.c

   1
   2 #include "Python.h"
   3
   4 #if defined(__sgi) && defined(WITH_THREAD) && !defined(_SGI_MP_SOURCE)
   5 #define _SGI_MP_SOURCE
   6 #endif
   7
   8 /* Convert a possibly signed character to a nonnegative int */
   9 /* XXX This assumes characters are 8 bits wide */
  10 #ifdef __CHAR_UNSIGNED__
  11 #define Py_CHARMASK(c)          (c)
  12 #else
  13 #define Py_CHARMASK(c)          ((c) & 0xff)
  14 #endif
  15
  16 /* strtol and strtoul, renamed to avoid conflicts */
  17
  18 /*
  19 **      strtoul
  20 **              This is a general purpose routine for converting
  21 **              an ascii string to an integer in an arbitrary base.
  22 **              Leading white space is ignored.  If 'base' is zero
  23 **              it looks for a leading 0, 0x or 0X to tell which
  24 **              base.  If these are absent it defaults to 10.
  25 **              Base must be 0 or between 2 and 36 (inclusive).
  26 **              If 'ptr' is non-NULL it will contain a pointer to
  27 **              the end of the scan.
  28 **              Errors due to bad pointers will probably result in
  29 **              exceptions - we don't check for them.
  30 */
  31
  32 #include <ctype.h>
  33 #ifndef DONT_HAVE_ERRNO_H
  34 #include <errno.h>
  35 #endif
  36
  37 unsigned long
  38 PyOS_strtoul(register char *str, char **ptr, int base)
  39 {
  40     register unsigned long      result; /* return value of the function */
  41     register int                c;      /* current input character */
  42     register unsigned long      temp;   /* used in overflow testing */
  43     int                         ovf;    /* true if overflow occurred */
  44
  45     result = 0;
  46     ovf = 0;
  47
  48 /* catch silly bases */
  49     if (base != 0 && (base < 2 || base > 36))
  50     {
  51         if (ptr)
  52             *ptr = str;
  53         return 0;
  54     }
  55
  56 /* skip leading white space */
  57     while (*str && isspace(Py_CHARMASK(*str)))
  58         str++;
  59
  60 /* check for leading 0 or 0x for auto-base or base 16 */
  61     switch (base)
  62     {
  63     case 0:             /* look for leading 0, 0x or 0X */
  64         if (*str == '0')
  65         {
  66             str++;
  67             if (*str == 'x' || *str == 'X')
  68             {
  69                 str++;
  70                 base = 16;
  71             }
  72             else
  73                 base = 8;
  74         }
  75         else
  76             base = 10;
  77         break;
  78
  79     case 16:    /* skip leading 0x or 0X */
  80         if (*str == '0' && (*(str+1) == 'x' || *(str+1) == 'X'))
  81             str += 2;
  82         break;
  83     }
  84
  85 /* do the conversion */
  86     while ((c = Py_CHARMASK(*str)) != '\0')
  87     {
  88         if (isdigit(c) && c - '0' < base)
  89             c -= '0';
  90         else
  91         {
  92             if (isupper(c))
  93                 c = tolower(c);
  94             if (c >= 'a' && c <= 'z')
  95                 c -= 'a' - 10;
  96             else        /* non-"digit" character */
  97                 break;
  98             if (c >= base)      /* non-"digit" character */
  99                 break;
 100         }
 101         temp = result;
 102         result = result * base + c;
 103         if(base == 10) {
 104                 if(((long)(result - c) / base != (long)temp))   /* overflow */
 105                         ovf = 1;
 106         }
 107         else {
 108                 if ((result - c) / base != temp)        /* overflow */
 109                         ovf = 1;
 110         }
 111         str++;
 112     }
 113
 114 /* set pointer to point to the last character scanned */
 115     if (ptr)
 116         *ptr = str;
 117     if (ovf)
 118     {
 119         result = (unsigned long) ~0L;
 120         errno = ERANGE;
 121     }
 122     return result;
 123 }
 124
 125 long
 126 PyOS_strtol(char *str, char **ptr, int base)
 127 {
 128         long result;
 129         char sign;
 130
 131         while (*str && isspace(Py_CHARMASK(*str)))
 132                 str++;
 133
 134         sign = *str;
 135         if (sign == '+' || sign == '-')
 136                 str++;
 137
 138         result = (long) PyOS_strtoul(str, ptr, base);
 139
 140         /* Signal overflow if the result appears negative,
 141            except for the largest negative integer */
 142         if (result < 0 && !(sign == '-' && result == -result)) {
 143                 errno = ERANGE;
 144                 result = 0x7fffffff;
 145         }
 146
 147         if (sign == '-')
 148                 result = -result;
 149
 150         return result;
 151 }