source: trunk/essentials/dev-lang/perl/uts/strtol_wrap.c

/* A wrapper around strtol() and strtoul() to correct some
 * "out of bounds" cases that don't work well on at least UTS.
 * If a value is Larger than the max, strto[u]l should return
 * the max value, and set errno to ERANGE
 *  The same if a value is smaller than the min value (only
 * relevant for strtol(); not strtoul()), except the minimum
 * value is returned (and errno == ERANGE).
 */

#include        <ctype.h>
#include        <string.h>
#include        <sys/errno.h>
#include        <stdlib.h>

extern int      errno;

#undef  I32
#undef  U32

#define I32     int
#define U32     unsigned int

struct  base_info {
        char    *ValidChars;

        char    *Ulong_max_str;
        char    *Long_max_str;
        char    *Long_min_str;  /* Absolute value */

        int     Ulong_max_str_len;
        int     Long_max_str_len;
        int     Long_min_str_len;       /* Absolute value */

        U32     Ulong_max;
        I32     Long_max;
        I32     Long_min;       /* NOT Absolute value */
};
static struct   base_info Base_info[37];

static struct base_info Base_info_16 = {
        "0123456789abcdefABCDEF",
        "4294967295", "2147483648" /* <== ABS VAL */ , "2147483647",
        10, 10, 10,
        4294967295, 2147483647, - 2147483648,
};

static struct base_info Base_info_10 = {
        "0123456789",
        "4294967295", "2147483648" /* <== ABS VAL */ , "2147483647",
        10, 10, 10,
        4294967295, 2147483647, - 2147483648,
};

 /* Used eventually (if this is fully developed) to hold info
  * for processing bases 2-36.  So that we can just plug the
  * base in as a selector for its info, we sacrifice
  * Base_info[0] and Base_info[1] (unless they are used
  * at some point for special information).
  */

/* This may be replaced later by something more universal */
static void
init_Base_info()
{
        if(Base_info[10].ValidChars) return;
        Base_info[10] = Base_info_10;
        Base_info[16] = Base_info_16;
}

unsigned int
strtoul_wrap32(char *s, char **pEnd, int base)
{
        int     Len;
        int     isNegated = 0;
        char    *sOrig = s;

        init_Base_info();

        while(*s && isspace(*s)) ++s;

        if(*s == '-') {
                ++isNegated;
                ++s;
                while(*s && isspace(*s)) ++s;
        }
        if(base == 0) {
                if(*s == '0') {
                        if(s[1] == 'x' || s[1] == 'X') {
                                s += 2;
                                base = 16;
                        } else {
                                ++s;
                                base = 8;
                        }
                } else if(isdigit(*s)) {
                        base = 10;
                }
        }
        if(base != 10) {
                return strtoul(sOrig, pEnd, base);
        }
        
        Len = strspn(s, Base_info[base].ValidChars);

        if(Len > Base_info[base].Ulong_max_str_len
                ||
           (Len == Base_info[base].Ulong_max_str_len
                        &&
            strncmp(Base_info[base].Ulong_max_str, s, Len) < 0)
          ) {
                /* In case isNegated is set - what to do?? */
                /* Mightn't we say a negative number is ERANGE for strtoul? */
                errno = ERANGE;
                return Base_info[base].Ulong_max;
        }

        return strtoul(sOrig, pEnd, base);
}

int
strtol_wrap32(char *s, char **pEnd, int base)
{
        int     Len;
        int     isNegated = 0;
        char    *sOrig = s;

        init_Base_info();

        while(*s && isspace(*s)) ++s;

        if(*s == '-') {
                ++isNegated;
                ++s;
                while(*s && isspace(*s)) ++s;
        }
        if(base == 0) {
                if(*s == '0') {
                        if(s[1] == 'x' || s[1] == 'X') {
                                s += 2;
                                base = 16;
                        } else {
                                ++s;
                                base = 8;
                        }
                } else if(isdigit(*s)) {
                        base = 10;
                }
        }
        if(base != 10) {
                return strtol(sOrig, pEnd, base);
        }
        
        Len = strspn(s, Base_info[base].ValidChars);

        if(Len > Base_info[base].Long_max_str_len
                                ||
           (!isNegated && Len == Base_info[base].Long_max_str_len
                &&
            strncmp(Base_info[base].Long_max_str, s, Len) < 0)
                                ||
           (isNegated && Len == Base_info[base].Long_min_str_len
                &&
            strncmp(Base_info[base].Long_min_str, s, Len) < 0)
          ) {
                /* In case isNegated is set - what to do?? */
                /* Mightn't we say a negative number is ERANGE for strtol? */
                errno = ERANGE;
                return(isNegated ? Base_info[base].Long_min
                                        :
                                   Base_info[base].Long_min);
        }

        return strtol(sOrig, pEnd, base);
}