vsprintf.c

		if (!*fmt || !*str)
			break;

		switch(*fmt++) {
		case 'c':
		{
			char *s = (char *) va_arg(args,char*);
			if (field_width == -1)
				field_width = 1;
			do {
				*s++ = *str++;
			} while (--field_width > 0 && *str);
			num++;
		}
		continue;
		case 's':
		{
			char *s = (char *) va_arg(args, char *);
			if(field_width == -1)
				field_width = INT_MAX;
			/* first, skip leading white space in buffer */
			while (isspace(*str))
				str++;

			/* now copy until next white space */
			while (*str && !isspace(*str) && field_width--) {
				*s++ = *str++;
			}
			*s = '\0';
			num++;
		}
		continue;
		case 'n':
			/* return number of characters read so far */
		{
			int *i = (int *)va_arg(args,int*);
			*i = str - buf;
		}
		continue;
		case 'o':
			base = 8;
			break;
		case 'x':
		case 'X':
			base = 16;
			break;
		case 'i':
                        base = 0;
		case 'd':
			is_sign = 1;
		case 'u':
			break;
		case '%':
			/* looking for '%' in str */
			if (*str++ != '%') 
				return num;
			continue;
		default:
			/* invalid format; stop here */
			return num;
		}

		/* have some sort of integer conversion.
		 * first, skip white space in buffer.
		 */
		while (isspace(*str))
			str++;

		digit = *str;
		if (is_sign && digit == '-')
			digit = *(str + 1);

		if (!digit
                    || (base == 16 && !isxdigit(digit))
                    || (base == 10 && !isdigit(digit))
                    || (base == 8 && (!isdigit(digit) || digit > '7'))
                    || (base == 0 && !isdigit(digit)))
				break;

		switch(qualifier) {
		case 'H':	/* that's 'hh' in format */
			if (is_sign) {
				signed char *s = (signed char *) va_arg(args,signed char *);
				*s = (signed char) simple_strtol(str,&next,base);
			} else {
				unsigned char *s = (unsigned char *) va_arg(args, unsigned char *);
				*s = (unsigned char) simple_strtoul(str, &next, base);
			}
			break;
		case 'h':
			if (is_sign) {
				short *s = (short *) va_arg(args,short *);
				*s = (short) simple_strtol(str,&next,base);
			} else {
				unsigned short *s = (unsigned short *) va_arg(args, unsigned short *);
				*s = (unsigned short) simple_strtoul(str, &next, base);
			}
			break;
		case 'l':
			if (is_sign) {
				long *l = (long *) va_arg(args,long *);
				*l = simple_strtol(str,&next,base);
			} else {
				unsigned long *l = (unsigned long*) va_arg(args,unsigned long*);
				*l = simple_strtoul(str,&next,base);
			}
			break;
		case 'L':
			if (is_sign) {
				long long *l = (long long*) va_arg(args,long long *);
				*l = simple_strtoll(str,&next,base);
			} else {
				unsigned long long *l = (unsigned long long*) va_arg(args,unsigned long long*);
				*l = simple_strtoull(str,&next,base);
			}
			break;
		case 'Z':
		case 'z':
		{
			size_t *s = (size_t*) va_arg(args,size_t*);
			*s = (size_t) simple_strtoul(str,&next,base);
		}
		break;
		default:
			if (is_sign) {
				int *i = (int *) va_arg(args, int*);
				*i = (int) simple_strtol(str,&next,base);
			} else {
				unsigned int *i = (unsigned int*) va_arg(args, unsigned int*);
				*i = (unsigned int) simple_strtoul(str,&next,base);
			}
			break;
		}
		num++;

		if (!next)
			break;
		str = next;
	}

	/*
	 * Now we've come all the way through so either the input string or the
	 * format ended. In the former case, there can be a %n at the current
	 * position in the format that needs to be filled.
	 */
	if (*fmt == '%' && *(fmt + 1) == 'n') {
		int *p = (int *)va_arg(args, int *);
		*p = str - buf;
	}

	return num;
}

EXPORT_SYMBOL(vsscanf);

/**
 * sscanf - Unformat a buffer into a list of arguments
 * @buf:	input buffer
 * @fmt:	formatting of buffer
 * @...:	resulting arguments
 */
int sscanf(const char * buf, const char * fmt, ...)
{
	va_list args;
	int i;

	va_start(args,fmt);
	i = vsscanf(buf,fmt,args);
	va_end(args);
	return i;
}

EXPORT_SYMBOL(sscanf);