lib/ansi/strtol.c

   1 /*
   2  * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
   3  * See the copyright notice in the ACK home directory, in the file "Copyright".
   4  */
   5 /* $Header$ */
   6
   7 #include        <ctype.h>
   8 #include        <errno.h>
   9 #include        <limits.h>
  10 #include        <stdlib.h>
  11
  12 static unsigned long
  13 string2long(register const char *nptr, char **endptr,
  14                         int base, int is_signed);
  15
  16 long int
  17 strtol(register const char *nptr, char **endptr, int base)
  18 {
  19         return (signed long)string2long(nptr, endptr, base, 1);
  20 }
  21
  22 unsigned long int
  23 strtoul(register const char *nptr, char **endptr, int base)
  24 {
  25         return (unsigned long)string2long(nptr, endptr, base, 0);
  26 }
  27
  28 #define between(a, c, z)  ((unsigned) ((c) - (a)) <= (unsigned) ((z) - (a)))
  29
  30 static unsigned long
  31 string2long(register const char *nptr, char ** const endptr,
  32                         int base, int is_signed)
  33 {
  34         register unsigned int v;
  35         register unsigned long val = 0;
  36         register int c;
  37         int ovfl = 0, sign = 1;
  38         const char *startnptr = nptr, *nrstart;
  39
  40         if (endptr) *endptr = (char *)nptr;
  41         while (isspace(*nptr)) nptr++;
  42         c = *nptr;
  43
  44         if (c == '-' || c == '+') {
  45                 if (c == '-') sign = -1;
  46                 nptr++;
  47         }
  48         nrstart = nptr;                 /* start of the number */
  49
  50         /* When base is 0, the syntax determines the actual base */
  51         if (base == 0)
  52                 if (*nptr == '0')
  53                         if (*++nptr == 'x' || *nptr == 'X') {
  54                                 base = 16;
  55                                 nptr++;
  56                         }
  57                         else    base = 8;
  58                 else    base = 10;
  59         else if (base==16 && *nptr=='0' && (*++nptr =='x' || *nptr =='X'))
  60                 nptr++;
  61
  62         for (;;) {
  63                 c = *nptr;
  64                 if (between('0', c, '9')) {
  65                         v = c - '0';
  66                 } else
  67                 if (between('a', c, 'z')) {
  68                         v = c - 'a' + 0xa;
  69                 } else
  70                 if (between('A', c, 'Z')) {
  71                         v = c - 'A' + 0xA;
  72                 } else {
  73                         break;
  74                 }
  75                 if (v >= base) break;
  76                 if (val > (ULONG_MAX - v) / base) ovfl++;
  77                 val = (val * base) + v;
  78                 nptr++;
  79         }
  80         if (endptr) {
  81                 if (nrstart == nptr) *endptr = (char *)startnptr;
  82                 else *endptr = (char *)nptr;
  83         }
  84
  85         if (!ovfl) {
  86                 /* Overflow is only possible when converting a signed long. */
  87                 if (is_signed
  88                     && (   (sign < 0 && val > -(unsigned long)LONG_MIN)
  89                         || (sign > 0 && val > LONG_MAX)))
  90                     ovfl++;
  91         }
  92
  93         if (ovfl) {
  94                 errno = ERANGE;
  95                 if (is_signed)
  96                         if (sign < 0) return LONG_MIN;
  97                         else return LONG_MAX;
  98                 else return ULONG_MAX;
  99         }
 100         return (long) sign * val;
 101 }