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101 lines
1.9 KiB
C
101 lines
1.9 KiB
C
/*
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* strtol : convert a string to long.
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*
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* Andy Wilson, 2-Oct-89.
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*/
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#include <errno.h>
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#include <ctype.h>
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#include <stdio.h>
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#ifndef ULONG_MAX
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#define ULONG_MAX ((unsigned long)(~0L)) /* 0xFFFFFFFF */
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#endif
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extern int errno;
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unsigned long
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strtoul(s, ptr, base)
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const char *s; char **ptr; int base;
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{
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unsigned long total = 0;
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unsigned digit;
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const char *start=s;
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int did_conversion=0;
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int overflow = 0;
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int negate = 0;
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unsigned long maxdiv, maxrem;
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if (s==NULL)
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{
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errno = ERANGE;
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if (!ptr)
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*ptr = (char *)start;
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return 0L;
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}
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while (isspace(*s))
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s++;
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if (*s == '+')
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s++;
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else if (*s == '-')
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s++, negate = 1;
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if (base==0 || base==16) /* the 'base==16' is for handling 0x */
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{
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int tmp;
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/*
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* try to infer base from the string
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*/
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if (*s != '0')
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tmp = 10; /* doesn't start with 0 - assume decimal */
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else if (s[1] == 'X' || s[1] == 'x')
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tmp = 16, s += 2; /* starts with 0x or 0X - hence hex */
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else
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tmp = 8; /* starts with 0 - hence octal */
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if (base==0)
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base = (int)tmp;
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}
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maxdiv = ULONG_MAX / base;
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maxrem = ULONG_MAX % base;
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while ((digit = *s) != '\0')
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{
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if (digit >= '0' && digit < ('0'+base))
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digit -= '0';
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else
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if (base > 10)
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{
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if (digit >= 'a' && digit < ('a'+(base-10)))
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digit = digit - 'a' + 10;
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else if (digit >= 'A' && digit < ('A'+(base-10)))
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digit = digit - 'A' + 10;
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else
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break;
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}
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else
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break;
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did_conversion = 1;
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if (total > maxdiv
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|| (total == maxdiv && digit > maxrem))
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overflow = 1;
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total = (total * base) + digit;
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s++;
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}
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if (overflow)
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{
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errno = ERANGE;
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if (ptr != NULL)
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*ptr = (char *)s;
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return (ULONG_MAX);
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}
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if (ptr != NULL)
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*ptr = (char *) ((did_conversion) ? (char *)s : (char *)start);
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return negate ? -total : total;
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}
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