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/*
 * Copyright (C) 2005 Martin Decky
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <string.h>
#include <unistd.h>
#include <ctype.h>
#include <limits.h>


/* Dummy implementation of mem/ functions */

void * memset(void *s, int c, size_t n)
{
    char *os = s;
    while (n--)
        *(os++) = c;
    return s;
}

void * memcpy(void *dest, void *src, size_t n)
{
    char *os = src;
    char *odst = dest;
    while (n--)
        *(odst++) = *(os++);
    return dest;
}

/** Count the number of characters in the string, not including terminating 0.
 * @param str string
 * @return number of characters in string.
 */
size_t strlen(const char *str) 
{
    size_t counter = 0;

    while (str[counter] != 0) {
        counter++;
    }

    return counter;
}

/** Return pointer to the first occurence of character c in string
 * @param str scanned string 
 * @param c searched character (taken as one byte)
 * @return pointer to the matched character or NULL if it is not found in given string.
 */
char *strchr(const char *str, int c)
{
    while (*str != '\0') {
        if (*str == (char)c)
            return (char *)str;
        str++;
    }

    return NULL;
}

/** Return pointer to the last occurence of character c in string
 * @param str scanned string 
 * @param c searched character (taken as one byte)
 * @return pointer to the matched character or NULL if it is not found in given string.
 */
char *strrchr(const char *str, int c)
{
    char *retval = NULL;

    while (*str != '\0') {
        if (*str == (char)c)
            retval = (char *)str;
        str++;
    }

    return (char *)retval;
}

/** Convert string to a number. 
 * Core of strtol and strtoul functions.
 * @param nptr pointer to string
 * @param endptr if not NULL, function stores here pointer to the first invalid character
 * @param base zero or number between 2 and 36 inclusive
 * @param sgn its set to 1 if minus found
 * @return result of conversion.
 */
static unsigned long _strtoul(const char *nptr, char **endptr, int base, char *sgn)
{
    unsigned char c;
    unsigned long result = 0;
    unsigned long a, b;
    const char *str = nptr;
    const char *tmpptr;
    
    while (isspace(*str))
        str++;
    
    if (*str == '-') {
        *sgn = 1;
        ++str;
    } else if (*str == '+')
        ++str;
    
    if (base) {
        if ((base == 1) || (base > 36)) {
            /* FIXME: set errno to EINVAL */
            return 0;
        }
        if ((base == 16) && (*str == '0') && ((str[1] == 'x') || (str[1] == 'X'))) {
            str += 2;
        }
    } else {
        base = 10;
        
        if (*str == '0') {
            base = 8;
            if ((str[1] == 'X') || (str[1] == 'x'))  {
                base = 16;
                str += 2;
            }
        } 
    }
    
    tmpptr = str;

    while (*str) {
        c = *str;
        c = ( c >= 'a'? c-'a'+10:(c >= 'A'?c-'A'+10:(c <= '9'?c-'0':0xff)));
        if (c > base) {
            break;
        }
        
        a = (result & 0xff) * base + c;
        b = (result >> 8) * base + (a >> 8);
        
        if (b > (ULONG_MAX >> 8)) {
            /* overflow */
            /* FIXME: errno = ERANGE*/
            return ULONG_MAX;
        }
    
        result = (b << 8) + (a & 0xff);
        ++str;
    }
    
    if (str == tmpptr) {
        /* no number was found => first invalid character is the first character of the string */
        /* FIXME: set errno to EINVAL */
        str = nptr;
        result = 0;
    }
    
    if (endptr)
        *endptr = (char *)str;

    if (nptr == str) { 
        /*FIXME: errno = EINVAL*/
        return 0;
    }

    return result;
}

/** Convert initial part of string to long int according to given base.
 * The number may begin with an arbitrary number of whitespaces followed by optional sign (`+' or `-').
 * If the base is 0 or 16, the prefix `0x' may be inserted and the number will be taken as hexadecimal one.
 * If the base is 0 and the number begin with a zero, number will be taken as octal one (as with base 8).
 * Otherwise the base 0 is taken as decimal.
 * @param nptr pointer to string
 * @param endptr if not NULL, function stores here pointer to the first invalid character
 * @param base zero or number between 2 and 36 inclusive
 * @return result of conversion.
 */
long int strtol(const char *nptr, char **endptr, int base)
{
    char sgn = 0;
    unsigned long number = 0;
    
    number = _strtoul(nptr, endptr, base, &sgn);

    if (number > LONG_MAX) {
        if ((sgn) && (number == (unsigned long)(LONG_MAX) + 1)) {
            /* FIXME: set 0 to errno */
            return number;      
        }
        /* FIXME: set ERANGE to errno */
        return (sgn?LONG_MIN:LONG_MAX); 
    }
    
    return (sgn?-number:number);
}


/** Convert initial part of string to unsigned long according to given base.
 * The number may begin with an arbitrary number of whitespaces followed by optional sign (`+' or `-').
 * If the base is 0 or 16, the prefix `0x' may be inserted and the number will be taken as hexadecimal one.
 * If the base is 0 and the number begin with a zero, number will be taken as octal one (as with base 8).
 * Otherwise the base 0 is taken as decimal.
 * @param nptr pointer to string
 * @param endptr if not NULL, function stores here pointer to the first invalid character
 * @param base zero or number between 2 and 36 inclusive
 * @return result of conversion.
 */
unsigned long strtoul(const char *nptr, char **endptr, int base)
{
    char sgn = 0;
    unsigned long number = 0;
    
    number = _strtoul(nptr, endptr, base, &sgn);

    return (sgn?-number:number);
}