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>	/* for KSYM_SYMBOL_LEN */
#include <linux/types.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/kernel.h>
#include <linux/kallsyms.h>
#include <linux/math64.h>
#include <linux/uaccess.h>
#include <linux/ioport.h>
#include <linux/dcache.h>
#include <linux/cred.h>
#include <net/addrconf.h>

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

#include <linux/string_helpers.h>
#include "kstrtox.h"

/**
 * 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
 *
 * This function is obsolete. Please use kstrtoull instead.
 */
unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base)
{
	unsigned long long result;
	unsigned int rv;

	cp = _parse_integer_fixup_radix(cp, &base);
	rv = _parse_integer(cp, base, &result);
	/* FIXME */
	cp += (rv & ~KSTRTOX_OVERFLOW);

	if (endp)
		*endp = (char *)cp;

	return result;
}
EXPORT_SYMBOL(simple_strtoull);

/**
 * 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
 *
 * This function is obsolete. Please use kstrtoul instead.
 */
unsigned long simple_strtoul(const char *cp, char **endp, unsigned int base)
{
	return simple_strtoull(cp, endp, base);
}
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
 *
 * This function is obsolete. Please use kstrtol instead.
 */
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_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
 *
 * This function is obsolete. Please use kstrtoll instead.
 */
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);
}
EXPORT_SYMBOL(simple_strtoll);

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

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

	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 ideas described at <http://www.cs.uiowa.edu/~jones/bcd/divide.html>
 * (with permission from the author, Douglas W. Jones).
 */

#if BITS_PER_LONG != 32 || BITS_PER_LONG_LONG != 64
/* Formats correctly any integer in [0, 999999999] */
static noinline_for_stack
char *put_dec_full9(char *buf, unsigned q)
{
	unsigned r;

	/*
	 * Possible ways to approx. divide by 10
	 * (x * 0x1999999a) >> 32 x < 1073741829 (multiply must be 64-bit)
	 * (x * 0xcccd) >> 19     x <      81920 (x < 262149 when 64-bit mul)
	 * (x * 0x6667) >> 18     x <      43699
	 * (x * 0x3334) >> 17     x <      16389
	 * (x * 0x199a) >> 16     x <      16389
	 * (x * 0x0ccd) >> 15     x <      16389
	 * (x * 0x0667) >> 14     x <       2739
	 * (x * 0x0334) >> 13     x <       1029
	 * (x * 0x019a) >> 12     x <       1029
	 * (x * 0x00cd) >> 11     x <       1029 shorter code than * 0x67 (on i386)
	 * (x * 0x0067) >> 10     x <        179
	 * (x * 0x0034) >>  9     x <         69 same
	 * (x * 0x001a) >>  8     x <         69 same
	 * (x * 0x000d) >>  7     x <         69 same, shortest code (on i386)
	 * (x * 0x0007) >>  6     x <         19
	 * See <http://www.cs.uiowa.edu/~jones/bcd/divide.html>
	 */
	r      = (q * (uint64_t)0x1999999a) >> 32;
	*buf++ = (q - 10 * r) + '0'; /* 1 */
	q      = (r * (uint64_t)0x1999999a) >> 32;
	*buf++ = (r - 10 * q) + '0'; /* 2 */
	r      = (q * (uint64_t)0x1999999a) >> 32;
	*buf++ = (q - 10 * r) + '0'; /* 3 */
	q      = (r * (uint64_t)0x1999999a) >> 32;
	*buf++ = (r - 10 * q) + '0'; /* 4 */
	r      = (q * (uint64_t)0x1999999a) >> 32;
	*buf++ = (q - 10 * r) + '0'; /* 5 */
	/* Now value is under 10000, can avoid 64-bit multiply */
	q      = (r * 0x199a) >> 16;
	*buf++ = (r - 10 * q)  + '0'; /* 6 */
	r      = (q * 0xcd) >> 11;
	*buf++ = (q - 10 * r)  + '0'; /* 7 */
	q      = (r * 0xcd) >> 11;
	*buf++ = (r - 10 * q) + '0'; /* 8 */
	*buf++ = q + '0'; /* 9 */
	return buf;
}
#endif

/* Similar to above but do not pad with zeros.
 * Code can be easily arranged to print 9 digits too, but our callers
 * always call put_dec_full9() instead when the number has 9 decimal digits.
 */
static noinline_for_stack
char *put_dec_trunc8(char *buf, unsigned r)
{
	unsigned q;

	/* Copy of previous function's body with added early returns */
	while (r >= 10000) {
		q = r + '0';
		r  = (r * (uint64_t)0x1999999a) >> 32;
		*buf++ = q - 10*r;
	}

	q      = (r * 0x199a) >> 16;	/* r <= 9999 */
	*buf++ = (r - 10 * q)  + '0';
	if (q == 0)
		return buf;
	r      = (q * 0xcd) >> 11;	/* q <= 999 */
	*buf++ = (q - 10 * r)  + '0';
	if (r == 0)
		return buf;
	q      = (r * 0xcd) >> 11;	/* r <= 99 */
	*buf++ = (r - 10 * q) + '0';
	if (q == 0)
		return buf;
	*buf++ = q + '0';		 /* q <= 9 */
	return buf;
}

/* There are two algorithms to print larger numbers.
 * One is generic: divide by 1000000000 and repeatedly print
 * groups of (up to) 9 digits. It's conceptually simple,
 * but requires a (unsigned long long) / 1000000000 division.
 *
 * Second algorithm splits 64-bit unsigned long long into 16-bit chunks,
 * manipulates them cleverly and generates groups of 4 decimal digits.
 * It so happens that it does NOT require long long division.
 *
 * If long is > 32 bits, division of 64-bit values is relatively easy,
 * and we will use the first algorithm.
 * If long long is > 64 bits (strange architecture with VERY large long long),
 * second algorithm can't be used, and we again use the first one.
 *
 * Else (if long is 32 bits and long long is 64 bits) we use second one.
 */

#if BITS_PER_LONG != 32 || BITS_PER_LONG_LONG != 64

/* First algorithm: generic */

static
char *put_dec(char *buf, unsigned long long n)
{
	if (n >= 100*1000*1000) {
		while (n >= 1000*1000*1000)
			buf = put_dec_full9(buf, do_div(n, 1000*1000*1000));
		if (n >= 100*1000*1000)
			return put_dec_full9(buf, n);
	}
	return put_dec_trunc8(buf, n);
}

#else

/* Second algorithm: valid only for 64-bit long longs */

/* See comment in put_dec_full9 for choice of constants */
static noinline_for_stack
void put_dec_full4(char *buf, unsigned q)
{
	unsigned r;
	r      = (q * 0xccd) >> 15;
	buf[0] = (q - 10 * r) + '0';
	q      = (r * 0xcd) >> 11;
	buf[1] = (r - 10 * q)  + '0';
	r      = (q * 0xcd) >> 11;
	buf[2] = (q - 10 * r)  + '0';
	buf[3] = r + '0';
}

/*
 * Call put_dec_full4 on x % 10000, return x / 10000.
 * The approximation x/10000 == (x * 0x346DC5D7) >> 43
 * holds for all x < 1,128,869,999.  The largest value this
 * helper will ever be asked to convert is 1,125,520,955.
 * (d1 in the put_dec code, assuming n is all-ones).
 */
static
unsigned put_dec_helper4(char *buf, unsigned x)
{
        uint32_t q = (x * (uint64_t)0x346DC5D7) >> 43;

        put_dec_full4(buf, x - q * 10000);
        return q;
}

/* Based on code by Douglas W. Jones found at
 * <http://www.cs.uiowa.edu/~jones/bcd/decimal.html#sixtyfour>
 * (with permission from the author).
 * Performs no 64-bit division and hence should be fast on 32-bit machines.
 */
static
char *put_dec(char *buf, unsigned long long n)
{
	uint32_t d3, d2, d1, q, h;

	if (n < 100*1000*1000)
		return put_dec_trunc8(buf, n);

	d1  = ((uint32_t)n >> 16); /* implicit "& 0xffff" */
	h   = (n >> 32);
	d2  = (h      ) & 0xffff;
	d3  = (h >> 16); /* implicit "& 0xffff" */

	q   = 656 * d3 + 7296 * d2 + 5536 * d1 + ((uint32_t)n & 0xffff);
	q = put_dec_helper4(buf, q);

	q += 7671 * d3 + 9496 * d2 + 6 * d1;
	q = put_dec_helper4(buf+4, q);

	q += 4749 * d3 + 42 * d2;
	q = put_dec_helper4(buf+8, q);

	q += 281 * d3;
	buf += 12;
	if (q)
		buf = put_dec_trunc8(buf, q);
	else while (buf[-1] == '0')
		--buf;

	return buf;
}

#endif

/*
 * Convert passed number to decimal string.
 * Returns the length of string.  On buffer overflow, returns 0.
 *
 * If speed is not important, use snprintf(). It's easy to read the code.
 */
int num_to_str(char *buf, int size, unsigned long long num)
{
	char tmp[sizeof(num) * 3];
	int idx, len;

	/* put_dec() may work incorrectly for num = 0 (generate "", not "0") */
	if (num <= 9) {
		tmp[0] = '0' + num;
		len = 1;
	} else {
		len = put_dec(tmp, num) - tmp;
	}

	if (len > size)
		return 0;
	for (idx = 0; idx < len; ++idx)
		buf[idx] = tmp[len - idx - 1];
	return len;
}

#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		/* use lowercase in hex (must be 32 == 0x20) */
#define SPECIAL	64		/* prefix hex with "0x", octal with "0" */

enum format_type {
	FORMAT_TYPE_NONE, /* Just a string part */
	FORMAT_TYPE_WIDTH,
	FORMAT_TYPE_PRECISION,
	FORMAT_TYPE_CHAR,
	FORMAT_TYPE_STR,
	FORMAT_TYPE_PTR,
	FORMAT_TYPE_PERCENT_CHAR,
	FORMAT_TYPE_INVALID,
	FORMAT_TYPE_LONG_LONG,
	FORMAT_TYPE_ULONG,
	FORMAT_TYPE_LONG,
	FORMAT_TYPE_UBYTE,
	FORMAT_TYPE_BYTE,
	FORMAT_TYPE_USHORT,
	FORMAT_TYPE_SHORT,
	FORMAT_TYPE_UINT,
	FORMAT_TYPE_INT,
	FORMAT_TYPE_SIZE_T,
	FORMAT_TYPE_PTRDIFF
};

struct printf_spec {
	u8	type;		/* format_type enum */
	u8	flags;		/* flags to number() */
	u8	base;		/* number base, 8, 10 or 16 only */
	u8	qualifier;	/* number qualifier, one of 'hHlLtzZ' */
	s16	field_width;	/* width of output field */
	s16	precision;	/* # of digits/chars */
};

static noinline_for_stack
char *number(char *buf, char *end, unsigned long long num,
	     struct printf_spec spec)
{
	/* 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 = ((spec.flags & SPECIAL) && spec.base != 10);
	int i;
	bool is_zero = num == 0LL;

	/* locase = 0 or 0x20. ORing digits or letters with 'locase'
	 * produces same digits or (maybe lowercased) letters */
	locase = (spec.flags & SMALL);
	if (spec.flags & LEFT)
		spec.flags &= ~ZEROPAD;
	sign = 0;
	if (spec.flags & SIGN) {
		if ((signed long long)num < 0) {
			sign = '-';
			num = -(signed long long)num;
			spec.field_width--;
		} else if (spec.flags & PLUS) {
			sign = '+';
			spec.field_width--;
		} else if (spec.flags & SPACE) {
			sign = ' ';
			spec.field_width--;
		}
	}
	if (need_pfx) {
		if (spec.base == 16)
			spec.field_width -= 2;
		else if (!is_zero)
			spec.field_width--;
	}

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

		if (spec.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 > spec.precision)
		spec.precision = i;
	/* leading space padding */
	spec.field_width -= spec.precision;
	if (!(spec.flags & (ZEROPAD+LEFT))) {
		while (--spec.field_width >= 0) {
			if (buf < end)
				*buf = ' ';
			++buf;
		}
	}
	/* sign */
	if (sign) {
		if (buf < end)
			*buf = sign;
		++buf;
	}
	/* "0x" / "0" prefix */
	if (need_pfx) {
		if (spec.base == 16 || !is_zero) {
			if (buf < end)
				*buf = '0';
			++buf;
		}
		if (spec.base == 16) {
			if (buf < end)
				*buf = ('X' | locase);
			++buf;
		}
	}
	/* zero or space padding */
	if (!(spec.flags & LEFT)) {
		char c = (spec.flags & ZEROPAD) ? '0' : ' ';
		while (--spec.field_width >= 0) {
			if (buf < end)
				*buf = c;
			++buf;
		}
	}
	/* hmm even more zero padding? */
	while (i <= --spec.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 (--spec.field_width >= 0) {
		if (buf < end)
			*buf = ' ';
		++buf;
	}

	return buf;
}

static noinline_for_stack
char *string(char *buf, char *end, const char *s, struct printf_spec spec)
{
	int len, i;

	if ((unsigned long)s < PAGE_SIZE)
		s = "(null)";

	len = strnlen(s, spec.precision);

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

	return buf;
}

static void widen(char *buf, char *end, unsigned len, unsigned spaces)
{
	size_t size;
	if (buf >= end)	/* nowhere to put anything */
		return;
	size = end - buf;
	if (size <= spaces) {
		memset(buf, ' ', size);
		return;
	}
	if (len) {
		if (len > size - spaces)
			len = size - spaces;
		memmove(buf + spaces, buf, len);
	}
	memset(buf, ' ', spaces);
}

static noinline_for_stack
char *dentry_name(char *buf, char *end, const struct dentry *d, struct printf_spec spec,
		  const char *fmt)
{
	const char *array[4], *s;
	const struct dentry *p;
	int depth;
	int i, n;

	switch (fmt[1]) {
		case '2': case '3': case '4':
			depth = fmt[1] - '0';
			break;
		default:
			depth = 1;
	}

	rcu_read_lock();
	for (i = 0; i < depth; i++, d = p) {
		p = ACCESS_ONCE(d->d_parent);
		array[i] = ACCESS_ONCE(d->d_name.name);
		if (p == d) {
			if (i)
				array[i] = "";
			i++;
			break;
		}
	}
	s = array[--i];
	for (n = 0; n != spec.precision; n++, buf++) {
		char c = *s++;
		if (!c) {
			if (!i)
				break;
			c = '/';
			s = array[--i];
		}
		if (buf < end)
			*buf = c;
	}
	rcu_read_unlock();
	if (n < spec.field_width) {
		/* we want to pad the sucker */
		unsigned spaces = spec.field_width - n;
		if (!(spec.flags & LEFT)) {
			widen(buf - n, end, n, spaces);
			return buf + spaces;
		}
		while (spaces--) {
			if (buf < end)
				*buf = ' ';
			++buf;
		}
	}
	return buf;
}

static noinline_for_stack
char *symbol_string(char *buf, char *end, void *ptr,
		    struct printf_spec spec, const char *fmt)
{
	unsigned long value;
#ifdef CONFIG_KALLSYMS
	char sym[KSYM_SYMBOL_LEN];
#endif

	if (fmt[1] == 'R')
		ptr = __builtin_extract_return_addr(ptr);
	value = (unsigned long)ptr;

#ifdef CONFIG_KALLSYMS
	if (*fmt == 'B')
		sprint_backtrace(sym, value);
	else if (*fmt != 'f' && *fmt != 's')
		sprint_symbol(sym, value);
	else
		sprint_symbol_no_offset(sym, value);

	return string(buf, end, sym, spec);
#else
	spec.field_width = 2 * sizeof(void *);
	spec.flags |= SPECIAL | SMALL | ZEROPAD;
	spec.base = 16;

	return number(buf, end, value, spec);
#endif
}

static noinline_for_stack
char *resource_string(char *buf, char *end, struct resource *res,
		      struct printf_spec spec, const char *fmt)
{
#ifndef IO_RSRC_PRINTK_SIZE
#define IO_RSRC_PRINTK_SIZE	6
#endif

#ifndef MEM_RSRC_PRINTK_SIZE
#define MEM_RSRC_PRINTK_SIZE	10
#endif
	static const struct printf_spec io_spec = {
		.base = 16,
		.field_width = IO_RSRC_PRINTK_SIZE,
		.precision = -1,
		.flags = SPECIAL | SMALL | ZEROPAD,
	};
	static const struct printf_spec mem_spec = {
		.base = 16,
		.field_width = MEM_RSRC_PRINTK_SIZE,
		.precision = -1,
		.flags = SPECIAL | SMALL | ZEROPAD,
	};
	static const struct printf_spec bus_spec = {
		.base = 16,
		.field_width = 2,
		.precision = -1,
		.flags = SMALL | ZEROPAD,
	};
	static const struct printf_spec dec_spec = {
		.base = 10,
		.precision = -1,
		.flags = 0,
	};
	static const struct printf_spec str_spec = {
		.field_width = -1,
		.precision = 10,
		.flags = LEFT,
	};
	static const struct printf_spec flag_spec = {
		.base = 16,
		.precision = -1,
		.flags = SPECIAL | SMALL,
	};

	/* 32-bit res (sizeof==4): 10 chars in dec, 10 in hex ("0x" + 8)
	 * 64-bit res (sizeof==8): 20 chars in dec, 18 in hex ("0x" + 16) */
#define RSRC_BUF_SIZE		((2 * sizeof(resource_size_t)) + 4)
#define FLAG_BUF_SIZE		(2 * sizeof(res->flags))
#define DECODED_BUF_SIZE	sizeof("[mem - 64bit pref window disabled]")
#define RAW_BUF_SIZE		sizeof("[mem - flags 0x]")
	char sym[max(2*RSRC_BUF_SIZE + DECODED_BUF_SIZE,
		     2*RSRC_BUF_SIZE + FLAG_BUF_SIZE + RAW_BUF_SIZE)];

	char *p = sym, *pend = sym + sizeof(sym);
	int decode = (fmt[0] == 'R') ? 1 : 0;
	const struct printf_spec *specp;

	*p++ = '[';
	if (res->flags & IORESOURCE_IO) {
		p = string(p, pend, "io  ", str_spec);
		specp = &io_spec;
	} else if (res->flags & IORESOURCE_MEM) {
		p = string(p, pend, "mem ", str_spec);
		specp = &mem_spec;
	} else if (res->flags & IORESOURCE_IRQ) {
		p = string(p, pend, "irq ", str_spec);
		specp = &dec_spec;
	} else if (res->flags & IORESOURCE_DMA) {
		p = string(p, pend, "dma ", str_spec);
		specp = &dec_spec;
	} else if (res->flags & IORESOURCE_BUS) {
		p = string(p, pend, "bus ", str_spec);
		specp = &bus_spec;
	} else {
		p = string(p, pend, "??? ", str_spec);
		specp = &mem_spec;
		decode = 0;
	}
	if (decode && res->flags & IORESOURCE_UNSET) {
		p = string(p, pend, "size ", str_spec);
		p = number(p, pend, resource_size(res), *specp);
	} else {
		p = number(p, pend, res->start, *specp);
		if (res->start != res->end) {
			*p++ = '-';
			p = number(p, pend, res->end, *specp);
		}
	}
	if (decode) {
		if (res->flags & IORESOURCE_MEM_64)
			p = string(p, pend, " 64bit", str_spec);
		if (res->flags & IORESOURCE_PREFETCH)
			p = string(p, pend, " pref", str_spec);
		if (res->flags & IORESOURCE_WINDOW)
			p = string(p, pend, " window", str_spec);
		if (res->flags & IORESOURCE_DISABLED)
			p = string(p, pend, " disabled", str_spec);
	} else {
		p = string(p, pend, " flags ", str_spec);
		p = number(p, pend, res->flags, flag_spec);
	}
	*p++ = ']';
	*p = '\0';

	return string(buf, end, sym, spec);
}

static noinline_for_stack
char *hex_string(char *buf, char *end, u8 *addr, struct printf_spec spec,
		 const char *fmt)
{
	int i, len = 1;		/* if we pass '%ph[CDN]', field width remains
				   negative value, fallback to the default */
	char separator;

	if (spec.field_width == 0)
		/* nothing to print */
		return buf;

	if (ZERO_OR_NULL_PTR(addr))
		/* NULL pointer */
		return string(buf, end, NULL, spec);

	switch (fmt[1]) {
	case 'C':
		separator = ':';
		break;
	case 'D':
		separator = '-';
		break;
	case 'N':
		separator = 0;
		break;
	default:
		separator = ' ';
		break;
	}

	if (spec.field_width > 0)
		len = min_t(int, spec.field_width, 64);

	for (i = 0; i < len && buf < end - 1; i++) {
		buf = hex_byte_pack(buf, addr[i]);

		if (buf < end && separator && i != len - 1)
			*buf++ = separator;
	}

	return buf;
}

static noinline_for_stack
char *bitmap_string(char *buf, char *end, unsigned long *bitmap,
		    struct printf_spec spec, const char *fmt)
{
	const int CHUNKSZ = 32;
	int nr_bits = max_t(int, spec.field_width, 0);
	int i, chunksz;
	bool first = true;

	/* reused to print numbers */
	spec = (struct printf_spec){ .flags = SMALL | ZEROPAD, .base = 16 };

	chunksz = nr_bits & (CHUNKSZ - 1);
	if (chunksz == 0)
		chunksz = CHUNKSZ;

	i = ALIGN(nr_bits, CHUNKSZ) - CHUNKSZ;
	for (; i >= 0; i -= CHUNKSZ) {
		u32 chunkmask, val;
		int word, bit;

		chunkmask = ((1ULL << chunksz) - 1);
		word = i / BITS_PER_LONG;
		bit = i % BITS_PER_LONG;
		val = (bitmap[word] >> bit) & chunkmask;

		if (!first) {
			if (buf < end)
				*buf = ',';
			buf++;
		}
		first = false;

		spec.field_width = DIV_ROUND_UP(chunksz, 4);
		buf = number(buf, end, val, spec);

		chunksz = CHUNKSZ;
	}
	return buf;
}

static noinline_for_stack
char *bitmap_list_string(char *buf, char *end, unsigned long *bitmap,
			 struct printf_spec spec, const char *fmt)
{
	int nr_bits = max_t(int, spec.field_width, 0);
	/* current bit is 'cur', most recently seen range is [rbot, rtop] */
	int cur, rbot, rtop;
	bool first = true;

	/* reused to print numbers */
	spec = (struct printf_spec){ .base = 10 };

	rbot = cur = find_first_bit(bitmap, nr_bits);
	while (cur < nr_bits) {
		rtop = cur;
		cur = find_next_bit(bitmap, nr_bits, cur + 1);
		if (cur < nr_bits && cur <= rtop + 1)
			continue;

		if (!first) {
			if (buf < end)
				*buf = ',';
			buf++;
		}
		first = false;

		buf = number(buf, end, rbot, spec);
		if (rbot < rtop) {
			if (buf < end)
				*buf = '-';
			buf++;

			buf = number(buf, end, rtop, spec);
		}

		rbot = cur;
	}
	return buf;
}

static noinline_for_stack
char *mac_address_string(char *buf, char *end, u8 *addr,
			 struct printf_spec spec, const char *fmt)
{
	char mac_addr[sizeof("xx:xx:xx:xx:xx:xx")];
	char *p = mac_addr;
	int i;
	char separator;
	bool reversed = false;

	switch (fmt[1]) {
	case 'F':
		separator = '-';
		break;

	case 'R':
		reversed = true;
		/* fall through */

	default:
		separator = ':';
		break;
	}

	for (i = 0; i < 6; i++) {
		if (reversed)
			p = hex_byte_pack(p, addr[5 - i]);
		else
			p = hex_byte_pack(p, addr[i]);

		if (fmt[0] == 'M' && i != 5)
			*p++ = separator;
	}
	*p = '\0';

	return string(buf, end, mac_addr, spec);
}

static noinline_for_stack
char *ip4_string(char *p, const u8 *addr, const char *fmt)
{
	int i;
	bool leading_zeros = (fmt[0] == 'i');
	int index;
	int step;

	switch (fmt[2]) {
	case 'h':
#ifdef __BIG_ENDIAN
		index = 0;
		step = 1;
#else
		index = 3;
		step = -1;
#endif
		break;
	case 'l':
		index = 3;
		step = -1;
		break;
	case 'n':
	case 'b':
	default:
		index = 0;
		step = 1;
		break;
	}
	for (i = 0; i < 4; i++) {
		char temp[3];	/* hold each IP quad in reverse order */
		int digits = put_dec_trunc8(temp, addr[index]) - temp;
		if (leading_zeros) {
			if (digits < 3)
				*p++ = '0';
			if (digits < 2)
				*p++ = '0';
		}
		/* reverse the digits in the quad */
		while (digits--)
			*p++ = temp[digits];
		if (i < 3)
			*p++ = '.';
		index += step;
	}
	*p = '\0';

	return p;
}

static noinline_for_stack
char *ip6_compressed_string(char *p, const char *addr)
{
	int i, j, range;
	unsigned char zerolength[8];
	int longest = 1;
	int colonpos = -1;
	u16 word;
	u8 hi, lo;
	bool needcolon = false;
	bool useIPv4;
	struct in6_addr in6;

	memcpy(&in6, addr, sizeof(struct in6_addr));

	useIPv4 = ipv6_addr_v4mapped(&in6) || ipv6_addr_is_isatap(&in6);

	memset(zerolength, 0, sizeof(zerolength));

	if (useIPv4)
		range = 6;
	else
		range = 8;

	/* find position of longest 0 run */
	for (i = 0; i < range; i++) {
		for (j = i; j < range; j++) {
			if (in6.s6_addr16[j] != 0)
				break;
			zerolength[i]++;
		}
	}
	for (i = 0; i < range; i++) {
		if (zerolength[i] > longest) {
			longest = zerolength[i];
			colonpos = i;