path: root/lib/vsprintf.c

/*
 *  linux/lib/vsprintf.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/* vsprintf.c -- Lars Wirzenius & Linus Torvalds. */
/*
 * Wirzenius wrote this portably, Torvalds fucked it up :-)
 */

/* 
 * Fri Jul 13 2001 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
 * - changed to provide snprintf and vsnprintf functions
 * So Feb  1 16:51:32 CET 2004 Juergen Quade <quade@hsnr.de>
 * - scnprintf and vscnprintf
 */

#include <stdarg.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/kernel.h>

#include <asm/page.h>		/* for PAGE_SIZE */
#include <asm/div64.h>

/* Works only for digits and letters, but small and fast */
#define TOLOWER(x) ((x) | 0x20)

/**
 * simple_strtoul - convert a string to an unsigned long
 * @cp: The start of the string
 * @endp: A pointer to the end of the parsed string will be placed here
 * @base: The number base to use
 */
unsigned long simple_strtoul(const char *cp,char **endp,unsigned int base)
{
	unsigned long result = 0,value;

	if (!base) {
		base = 10;
		if (*cp == '0') {
			base = 8;
			cp++;
			if ((TOLOWER(*cp) == 'x') && isxdigit(cp[1])) {
				cp++;
				base = 16;
			}
		}
	} else if (base == 16) {
		if (cp[0] == '0' && TOLOWER(cp[1]) == 'x')
			cp += 2;
	}
	while (isxdigit(*cp) &&
	       (value = isdigit(*cp) ? *cp-'0' : TOLOWER(*cp)-'a'+10) < base) {
		result = result*base + value;
		cp++;
	}
	if (endp)
		*endp = (char *)cp;
	return result;
}

EXPORT_SYMBOL(simple_strtoul);

/**
 * simple_strtol - convert a string to a signed long
 * @cp: The start of the string
 * @endp: A pointer to the end of the parsed string will be placed here
 * @base: The number base to use
 */
long simple_strtol(const char *cp,char **endp,unsigned int base)
{
	if(*cp=='-')
		return -simple_strtoul(cp+1,endp,base);
	return simple_strtoul(cp,endp,base);
}

EXPORT_SYMBOL(simple_strtol);

/**
 * simple_strtoull - convert a string to an unsigned long long
 * @cp: The start of the string
 * @endp: A pointer to the end of the parsed string will be placed here
 * @base: The number base to use
 */
unsigned long long simple_strtoull(const char *cp,char **endp,unsigned int base)
{
	unsigned long long result = 0,value;

	if (!base) {
		base = 10;
		if (*cp == '0') {
			base = 8;
			cp++;
			if ((TOLOWER(*cp) == 'x') && isxdigit(cp[1])) {
				cp++;
				base = 16;
			}
		}
	} else if (base == 16) {
		if (cp[0] == '0' && TOLOWER(cp[1]) == 'x')
			cp += 2;
	}
	while (isxdigit(*cp)
	 && (value = isdigit(*cp) ? *cp-'0' : TOLOWER(*cp)-'a'+10) < base) {
		result = result*base + value;
		cp++;
	}
	if (endp)
		*endp = (char *)cp;
	return result;
}

EXPORT_SYMBOL(simple_strtoull);

/**
 * simple_strtoll - convert a string to a signed long long
 * @cp: The start of the string
 * @endp: A pointer to the end of the parsed string will be placed here
 * @base: The number base to use
 */
long long simple_strtoll(const char *cp,char **endp,unsigned int base)
{
	if(*cp=='-')
		return -simple_strtoull(cp+1,endp,base);
	return simple_strtoull(cp,endp,base);
}


/**
 * strict_strtoul - convert a string to an unsigned long strictly
 * @cp: The string to be converted
 * @base: The number base to use
 * @res: The converted result value
 *
 * strict_strtoul converts a string to an unsigned long only if the
 * string is really an unsigned long string, any string containing
 * any invalid char at the tail will be rejected and -EINVAL is returned,
 * only a newline char at the tail is acceptible because people generally
 * change a module parameter in the following way:
 *
 * 	echo 1024 > /sys/module/e1000/parameters/copybreak
 *
 * echo will append a newline to the tail.
 *
 * It returns 0 if conversion is successful and *res is set to the converted
 * value, otherwise it returns -EINVAL and *res is set to 0.
 *
 * simple_strtoul just ignores the successive invalid characters and
 * return the converted value of prefix part of the string.
 */
int strict_strtoul(const char *cp, unsigned int base, unsigned long *res);

/**
 * strict_strtol - convert a string to a long strictly
 * @cp: The string to be converted
 * @base: The number base to use
 * @res: The converted result value
 *
 * strict_strtol is similiar to strict_strtoul, but it allows the first
 * character of a string is '-'.
 *
 * It returns 0 if conversion is successful and *res is set to the converted
 * value, otherwise it returns -EINVAL and *res is set to 0.
 */
int strict_strtol(const char *cp, unsigned int base, long *res);

/**
 * strict_strtoull - convert a string to an unsigned long long strictly
 * @cp: The string to be converted
 * @base: The number base to use
 * @res: The converted result value
 *
 * strict_strtoull converts a string to an unsigned long long only if the
 * string is really an unsigned long long string, any string containing
 * any invalid char at the tail will be rejected and -EINVAL is returned,
 * only a newline char at the tail is acceptible because people generally
 * change a module parameter in the following way:
 *
 * 	echo 1024 > /sys/module/e1000/parameters/copybreak
 *
 * echo will append a newline to the tail of the string.
 *
 * It returns 0 if conversion is successful and *res is set to the converted
 * value, otherwise it returns -EINVAL and *res is set to 0.
 *
 * simple_strtoull just ignores the successive invalid characters and
 * return the converted value of prefix part of the string.
 */
int strict_strtoull(const char *cp, unsigned int base, unsigned long long *res);

/**
 * strict_strtoll - convert a string to a long long strictly
 * @cp: The string to be converted
 * @base: The number base to use
 * @res: The converted result value
 *
 * strict_strtoll is similiar to strict_strtoull, but it allows the first
 * character of a string is '-'.
 *
 * It returns 0 if conversion is successful and *res is set to the converted
 * value, otherwise it returns -EINVAL and *res is set to 0.
 */
int strict_strtoll(const char *cp, unsigned int base, long long *res);

#define define_strict_strtoux(type, valtype)				\
int strict_strtou##type(const char *cp, unsigned int base, valtype *res)\
{									\
	char *tail;							\
	valtype val;							\
	size_t len;							\
									\
	*res = 0;							\
	len = strlen(cp);						\
	if (len == 0)							\
		return -EINVAL;						\
									\
	val = simple_strtoul(cp, &tail, base);				\
	if ((*tail == '\0') ||						\
		((len == (size_t)(tail - cp) + 1) && (*tail == '\n'))) {\
		*res = val;						\
		return 0;						\
	}								\
									\
	return -EINVAL;							\
}									\

#define define_strict_strtox(type, valtype)				\
int strict_strto##type(const char *cp, unsigned int base, valtype *res)	\
{									\
	int ret;							\
	if (*cp == '-') {						\
		ret = strict_strtou##type(cp+1, base, res);		\
		if (!ret)						\
			*res = -(*res);					\
	} else								\
		ret = strict_strtou##type(cp, base, res);		\
									\
	return ret;							\
}									\

define_strict_strtoux(l, unsigned long)
define_strict_strtox(l, long)
define_strict_strtoux(ll, unsigned long long)
define_strict_strtox(ll, long long)

EXPORT_SYMBOL(strict_strtoul);
EXPORT_SYMBOL(strict_strtol);
EXPORT_SYMBOL(strict_strtoll);
EXPORT_SYMBOL(strict_strtoull);

static int skip_atoi(const char **s)
{
	int i=0;

	while (isdigit(**s))
		i = i*10 + *((*s)++) - '0';
	return i;
}

/* Decimal conversion is by far the most typical, and is used
 * for /proc and /sys data. This directly impacts e.g. top performance
 * with many processes running. We optimize it for speed
 * using code from
 * http://www.cs.uiowa.edu/~jones/bcd/decimal.html
 * (with permission from the author, Douglas W. Jones). */

/* Formats correctly any integer in [0,99999].
 * Outputs from one to five digits depending on input.
 * On i386 gcc 4.1.2 -O2: ~250 bytes of code. */
static char* put_dec_trunc(char *buf, unsigned q)
{
	unsigned d3, d2, d1, d0;
	d1 = (q>>4) & 0xf;
	d2 = (q>>8) & 0xf;
	d3 = (q>>12);

	d0 = 6*(d3 + d2 + d1) + (q & 0xf);
	q = (d0 * 0xcd) >> 11;
	d0 = d0 - 10*q;
	*buf++ = d0 + '0'; /* least significant digit */
	d1 = q + 9*d3 + 5*d2 + d1;
	if (d1 != 0) {
		q = (d1 * 0xcd) >> 11;
		d1 = d1 - 10*q;
		*buf++ = d1 + '0'; /* next digit */

		d2 = q + 2*d2;
		if ((d2 != 0) || (d3 != 0)) {
			q = (d2 * 0xd) >> 7;
			d2 = d2 - 10*q;
			*buf++ = d2 + '0'; /* next digit */

			d3 = q + 4*d3;
			if (d3 != 0) {
				q = (d3 * 0xcd) >> 11;
				d3 = d3 - 10*q;
				*buf++ = d3 + '0';  /* next digit */
				if (q != 0)
					*buf++ = q + '0';  /* most sign. digit */
			}
		}
	}
	return buf;
}
/* Same with if's removed. Always emits five digits */
static char* put_dec_full(char *buf, unsigned q)
{
	/* BTW, if q is in [0,9999], 8-bit ints will be enough, */
	/* but anyway, gcc produces better code with full-sized ints */
	unsigned d3, d2, d1, d0;
	d1 = (q>>4) & 0xf;
	d2 = (q>>8) & 0xf;
	d3 = (q>>12);

	/* Possible ways to approx. divide by 10 */
	/* gcc -O2 replaces multiply with shifts and adds */
	// (x * 0xcd) >> 11: 11001101 - shorter code than * 0x67 (on i386)
	// (x * 0x67) >> 10:  1100111
	// (x * 0x34) >> 9:    110100 - same
	// (x * 0x1a) >> 8:     11010 - same
	// (x * 0x0d) >> 7:      1101 - same, shortest code (on i386)

	d0 = 6*(d3 + d2 + d1) + (q & 0xf);
	q = (d0 * 0xcd) >> 11;
	d0 = d0 - 10*q;
	*buf++ = d0 + '0';
	d1 = q + 9*d3 + 5*d2 + d1;
		q = (d1 * 0xcd) >> 11;
		d1 = d1 - 10*q;
		*buf++ = d1 + '0';

		d2 = q + 2*d2;
			q = (d2 * 0xd) >> 7;
			d2 = d2 - 10*q;
			*buf++ = d2 + '0';

			d3 = q + 4*d3;
				q = (d3 * 0xcd) >> 11; /* - shorter code */
				/* q = (d3 * 0x67) >> 10; - would also work */
				d3 = d3 - 10*q;
				*buf++ = d3 + '0';
					*buf++ = q + '0';
	return buf;
}
/* No inlining helps gcc to use registers better */
static noinline char* put_dec(char *buf, unsigned long long num)
{
	while (1) {
		unsigned rem;
		if (num < 100000)
			return put_dec_trunc(buf, num);
		rem = do_div(num, 100000);
		buf = put_dec_full(buf, rem);
	}
}

#define ZEROPAD	1		/* pad with zero */
#define SIGN	2		/* unsigned/signed long */
#define PLUS	4		/* show plus */
#define SPACE	8		/* space if plus */
#define LEFT	16		/* left justified */
#define SMALL	32		/* Must be 32 == 0x20 */
#define SPECIAL	64		/* 0x */

static char *number(char *buf, char *end, unsigned long long num, int base, int size, int precision, int type)
{
	/* we are called with base 8, 10 or 16, only, thus don't need "G..."  */
	static const char digits[16] = "0123456789ABCDEF"; /* "GHIJKLMNOPQRSTUVWXYZ"; */

	char tmp[66];
	char sign;
	char locase;
	int need_pfx = ((type & SPECIAL) && base != 10);
	int i;

	/* locase = 0 or 0x20. ORing digits or letters with 'locase'
	 * produces same digits or (maybe lowercased) letters */
	locase = (type & SMALL);
	if (type & LEFT)
		type &= ~ZEROPAD;
	sign = 0;
	if (type & SIGN) {
		if ((signed long long) num < 0) {
			sign = '-';
			num = - (signed long long) num;
			size--;
		} else if (type & PLUS) {
			sign = '+';
			size--;
		} else if (type & SPACE) {
			sign = ' ';
			size--;
		}
	}
	if (need_pfx) {
		size--;
		if (base == 16)
			size--;
	}

	/* generate full string in tmp[], in reverse order */
	i = 0;
	if (num == 0)
		tmp[i++] = '0';
	/* Generic code, for any base:
	else do {
		tmp[i++] = (digits[do_div(num,base)] | locase);
	} while (num != 0);
	*/
	else if (base != 10) { /* 8 or 16 */
		int mask = base - 1;
		int shift = 3;
		if (base == 16) shift = 4;
		do {
			tmp[i++] = (digits[((unsigned char)num) & mask] | locase);
			num >>= shift;
		} while (num);
	} else { /* base 10 */
		i = put_dec(tmp, num) - tmp;
	}

	/* printing 100 using %2d gives "100", not "00" */
	if (i > precision)
		precision = i;
	/* leading space padding */
	size -= precision;
	if (!(type & (ZEROPAD+LEFT))) {
		while(--size >= 0) {
			if (buf < end)
				*buf = ' ';
			++buf;
		}
	}
	/* sign */
	if (sign) {
		if (buf < end)
			*buf = sign;
		++buf;
	}
	/* "0x" / "0" prefix */
	if (need_pfx) {
		if (buf < end)
			*buf = '0';
		++buf;
		if (base == 16) {
			if (buf < end)
				*buf = ('X' | locase);
			++buf;
		}
	}
	/* zero or space padding */
	if (!(type & LEFT)) {
		char c = (type & ZEROPAD) ? '0' : ' ';
		while (--size >= 0) {
			if (buf < end)
				*buf = c;
			++buf;
		}
	}
	/* hmm even more zero padding? */
	while (i <= --precision) {
		if (buf < end)
			*buf = '0';
		++buf;
	}
	/* actual digits of result */
	while (--i >= 0) {
		if (buf < end)
			*buf = tmp[i];
		++buf;
	}
	/* trailing space padding */
	while (--size >= 0) {
		if (buf < end)
			*buf = ' ';
		++buf;
	}
	return buf;
}

static char *string(char *buf, char *end, char *s, int field_width, int precision, int flags)
{
	int len, i;

	if ((unsigned long)s < PAGE_SIZE)
		s = "<NULL>";

	len = strnlen(s, precision);

	if (!(flags & LEFT)) {
		while (len < field_width--) {
			if (buf < end)
				*buf = ' ';
			++buf;
		}
	}
	for (i = 0; i < len; ++i) {
		if (buf < end)
			*buf = *s;
		++buf; ++s;
	}
	while (len < field_width--) {
		if (buf < end)
			*buf = ' ';
		++buf;
	}
	return buf;
}

/**
 * vsnprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @size: The size of the buffer, including the trailing null space
 * @fmt: The format string to use
 * @args: Arguments for the format string
 *
 * The return value is the number of characters which would
 * be generated for the given input, excluding the trailing
 * '\0', as per ISO C99. If you want to have the exact
 * number of characters written into @buf as return value
 * (not including the trailing '\0'), use vscnprintf(). If the
 * return is greater than or equal to @size, the resulting
 * string is truncated.
 *
 * Call this function if you are already dealing with a va_list.
 * You probably want snprintf() instead.
 */
int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
{
	unsigned long long num;
	int base;
	char *str, *end, c;

	int flags;		/* flags to number() */

	int field_width;	/* width of output field */
	int precision;		/* min. # of digits for integers; max
				   number of chars for from string */
	int qualifier;		/* 'h', 'l', or 'L' for integer fields */
				/* 'z' support added 23/7/1999 S.H.    */
				/* 'z' changed to 'Z' --davidm 1/25/99 */
				/* 't' added for ptrdiff_t */

	/* Reject out-of-range values early.  Large positive sizes are
	   used for unknown buffer sizes. */
	if (unlikely((int) size < 0)) {
		/* There can be only one.. */
		static char warn = 1;
		WARN_ON(warn);
		warn = 0;
		return 0;
	}

	str = buf;
	end = buf + size;

	/* Make sure end is always >= buf */
	if (end < buf) {
		end = ((void *)-1);
		size = end - buf;
	}

	for (; *fmt ; ++fmt) {
		if (*fmt != '%') {
			if (str < end)
				*str = *fmt;
			++str;
			continue;
		}

		/* process flags */
		flags = 0;
		repeat:
			++fmt;		/* this also skips first '%' */
			switch (*fmt) {
				case '-': flags |= LEFT; goto repeat;
				case '+': flags |= PLUS; goto repeat;
				case ' ': flags |= SPACE; goto repeat;
				case '#': flags |= SPECIAL; goto repeat;
				case '0': flags |= ZEROPAD; goto repeat;
			}

		/* get field width */
		field_width = -1;
		if (isdigit(*fmt))
			field_width = skip_atoi(&fmt);
		else if (*fmt == '*') {
			++fmt;
			/* it's the next argument */
			field_width = va_arg(args, int);
			if (field_width < 0) {
				field_width = -field_width;
				flags |= LEFT;
			}
		}

		/* get the precision */
		precision = -1;
		if (*fmt == '.') {
			++fmt;	
			if (isdigit(*fmt))
				precision = skip_atoi(&fmt);
			else if (*fmt == '*') {
				++fmt;
				/* it's the next argument */
				precision = va_arg(args, int);
			}
			if (precision < 0)
				precision = 0;
		}

		/* get the conversion qualifier */
		qualifier = -1;
		if (*fmt == 'h' || *fmt == 'l' || *fmt == 'L' ||
		    *fmt =='Z' || *fmt == 'z' || *fmt == 't') {
			qualifier = *fmt;
			++fmt;
			if (qualifier == 'l' && *fmt == 'l') {
				qualifier = 'L';
				++fmt;
			}
		}

		/* default base */
		base = 10;

		switch (*fmt) {
			case 'c':
				if (!(flags & LEFT)) {
					while (--field_width > 0) {
						if (str < end)
							*str = ' ';
						++str;
					}
				}
				c = (unsigned char) va_arg(args, int);
				if (str < end)
					*str = c;
				++str;
				while (--field_width > 0) {
					if (str < end)
						*str = ' ';
					++str;
				}
				continue;

			case 's':
				str = string(str, end, va_arg(args, char *), field_width, precision, flags);
				continue;

			case 'p':
				flags |= SMALL;
				if (field_width == -1) {
					field_width = 2*sizeof(void *);
					flags |= ZEROPAD;
				}
				str = number(str, end,
						(unsigned long) va_arg(args, void *),
						16, field_width, precision, flags);
				continue;


			case 'n':
				/* FIXME:
				* What does C99 say about the overflow case here? */
				if (qualifier == 'l') {
					long * ip = va_arg(args, long *);
					*ip = (str - buf);
				} else if (qualifier == 'Z' || qualifier == 'z') {
					size_t * ip = va_arg(args, size_t *);
					*ip = (str - buf);
				} else {
					int * ip = va_arg(args, int *);
					*ip = (str - buf);
				}
				continue;

			case '%':
				if (str < end)
					*str = '%';
				++str;
				continue;

				/* integer number formats - set up the flags and "break" */
			case 'o':
				base = 8;
				break;

			case 'x':
				flags |= SMALL;
			case 'X':
				base = 16;
				break;

			case 'd':
			case 'i':
				flags |= SIGN;
			case 'u':
				break;

			default:
				if (str < end)
					*str = '%';
				++str;
				if (*fmt) {
					if (str < end)
						*str = *fmt;
					++str;
				} else {
					--fmt;
				}
				continue;
		}
		if (qualifier == 'L')
			num = va_arg(args, long long);
		else if (qualifier == 'l') {
			num = va_arg(args, unsigned long);
			if (flags & SIGN)
				num = (signed long) num;
		} else if (qualifier == 'Z' || qualifier == 'z') {
			num = va_arg(args, size_t);
		} else if (qualifier == 't') {
			num = va_arg(args, ptrdiff_t);
		} else if (qualifier == 'h') {
			num = (unsigned short) va_arg(args, int);
			if (flags & SIGN)
				num = (signed short) num;
		} else {
			num = va_arg(args, unsigned int);
			if (flags & SIGN)
				num = (signed int) num;
		}
		str = number(str, end, num, base,
				field_width, precision, flags);
	}
	if (size > 0) {
		if (str < end)
			*str = '\0';
		else
			end[-1] = '\0';
	}
	/* the trailing null byte doesn't count towards the total */
	return str-buf;
}

EXPORT_SYMBOL(vsnprintf);

/**
 * vscnprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @size: The size of the buffer, including the trailing null space
 * @fmt: The format string to use
 * @args: Arguments for the format string
 *
 * The return value is the number of characters which have been written into
 * the @buf not including the trailing '\0'. If @size is <= 0 the function
 * returns 0.
 *
 * Call this function if you are already dealing with a va_list.
 * You probably want scnprintf() instead.
 */
int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
{
	int i;

	i=vsnprintf(buf,size,fmt,args);
	return (i >= size) ? (size - 1) : i;
}

EXPORT_SYMBOL(vscnprintf);

/**
 * snprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @size: The size of the buffer, including the trailing null space
 * @fmt: The format string to use
 * @...: Arguments for the format string
 *
 * The return value is the number of characters which would be
 * generated for the given input, excluding the trailing null,
 * as per ISO C99.  If the return is greater than or equal to
 * @size, the resulting string is truncated.
 */
int snprintf(char * buf, size_t size, const char *fmt, ...)
{
	va_list args;
	int i;

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

EXPORT_SYMBOL(snprintf);

/**
 * scnprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @size: The size of the buffer, including the trailing null space
 * @fmt: The format string to use
 * @...: Arguments for the format string
 *
 * The return value is the number of characters written into @buf not including
 * the trailing '\0'. If @size is <= 0 the function returns 0.
 */

int scnprintf(char * buf, size_t size, const char *fmt, ...)
{
	va_list args;
	int i;

	va_start(args, fmt);
	i = vsnprintf(buf, size, fmt, args);
	va_end(args);
	return (i >= size) ? (size - 1) : i;
}
EXPORT_SYMBOL(scnprintf);

/**
 * vsprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @fmt: The format string to use
 * @args: Arguments for the format string
 *
 * The function returns the number of characters written
 * into @buf. Use vsnprintf() or vscnprintf() in order to avoid
 * buffer overflows.
 *
 * Call this function if you are already dealing with a va_list.
 * You probably want sprintf() instead.
 */
int vsprintf(char *buf, const char *fmt, va_list args)
{
	return vsnprintf(buf, INT_MAX, fmt, args);
}

EXPORT_SYMBOL(vsprintf);

/**
 * sprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @fmt: The format string to use
 * @...: Arguments for the format string
 *
 * The function returns the number of characters written
 * into @buf. Use snprintf() or scnprintf() in order to avoid
 * buffer overflows.
 */
int sprintf(char * buf, const char *fmt, ...)
{
	va_list args;
	int i;

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

EXPORT_SYMBOL(sprintf);

/**
 * vsscanf - Unformat a buffer into a list of arguments
 * @buf:	input buffer
 * @fmt:	format of buffer
 * @args:	arguments
 */
int vsscanf(const char * buf, const char * fmt, va_list args)
{
	const char *str = buf;
	char *next;
	char digit;
	int num = 0;
	int qualifier;
	int base;
	int field_width;
	int is_sign = 0;

	while(*fmt && *str) {
		/* skip any white space in format */
		/* white space in format matchs any amount of
		 * white space, including none, in the input.
		 */
		if (isspace(*fmt)) {
			while (isspace(*fmt))
				++fmt;
			while (isspace(*str))
				++str;
		}

		/* anything that is not a conversion must match exactly */
		if (*fmt != '%' && *fmt) {
			if (*fmt++ != *str++)
				break;
			continue;
		}

		if (!*fmt)
			break;
		++fmt;
		
		/* skip this conversion.
		 * advance both strings to next white space
		 */
		if (*fmt == '*') {
			while (!isspace(*fmt) && *fmt)
				fmt++;
			while (!isspace(*str) && *str)
				str++;
			continue;
		}

		/* get field width */
		field_width = -1;
		if (isdigit(*fmt))
			field_width = skip_atoi(&fmt);

		/* get conversion qualifier */
		qualifier = -1;
		if (*fmt == 'h' || *fmt == 'l' || *fmt == 'L' ||
		    *fmt == 'Z' || *fmt == 'z') {
			qualifier = *fmt++;
			if (unlikely(qualifier == *fmt)) {
				if (qualifier == 'h') {
					qualifier = 'H';
					fmt++;
				} else if (qualifier == 'l') {
					qualifier = 'L';
					fmt++;
				}
			}
		}
		base = 10;
		is_sign = 0;

		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);