vsprintf.c

Lib files of linux kernel

/*
 *  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 <[e-mail]>
 * - changed to provide snprintf and vsnprintf functions
 * So Feb  1 16:51:32 CET 2004 Juergen Quade <[e-mail]>
 * - 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 <linux/kallsyms.h>
#include <linux/uaccess.h>

#include <asm/page.h>		/* for PAGE_SIZE */
#include <asm/div64.h>
#include <asm/sections.h>	/* for dereference_function_descriptor() */

/* 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_strtou##type(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;
}

static char *symbol_string(char *buf, char *end, void *ptr, int field_width, int precision, int flags)
{
	unsigned long value = (unsigned long) ptr;
#ifdef CONFIG_KALLSYMS
	char sym[KSYM_SYMBOL_LEN];
	sprint_symbol(sym, value);
	return string(buf, end, sym, field_width, precision, flags);
#else
	field_width = 2*sizeof(void *);
	flags |= SPECIAL | SMALL | ZEROPAD;
	return number(buf, end, value, 16, field_width, precision, flags);
#endif
}

/*
 * Show a '%p' thing.  A kernel extension is that the '%p' is followed
 * by an extra set of alphanumeric characters that are extended format
 * specifiers.
 *
 * Right now we just handle 'F' (for symbolic Function descriptor pointers)
 * and 'S' (for Symbolic direct pointers), but this can easily be
 * extended in the future (network address types etc).
 *
 * The difference between 'S' and 'F' is that on ia64 and ppc64 function
 * pointers are really function descriptors, which contain a pointer the
 * real address. 
 */
static char *pointer(const char *fmt, char *buf, char *end, void *ptr, int field_width, int precision, int flags)
{
	switch (*fmt) {
	case 'F':
		ptr = dereference_function_descriptor(ptr);
		/* Fallthrough */
	case 'S':
		return symbol_string(buf, end, ptr, field_width, precision, flags);
	}
	flags |= SMALL;
	if (field_width == -1) {
		field_width = 2*sizeof(void *);
		flags |= ZEROPAD;
	}
	return number(buf, end, (unsigned long) ptr, 16, field_width, precision, flags);
}

/**
 * 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)