Merge branches 'pci/enumeration', 'pci/virtualization' and 'pci/cleanup' into next

[linux/fpc-iii.git] / 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>       /* 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 "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 * This function is obsolete.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 * This function is obsolete.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 * This function is obsolete.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;

        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 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 *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;
                }
        }
        if (longest == 1)               /* don't compress a single 0 */
                colonpos = -1;

        /* emit address */
        for (i = 0; i < range; i++) {
                if (i == colonpos) {
                        if (needcolon || i == 0)
                                *p++ = ':';
                        *p++ = ':';
                        needcolon = false;
                        i += longest - 1;
                        continue;
                }
                if (needcolon) {
                        *p++ = ':';
                        needcolon = false;
                }
                /* hex u16 without leading 0s */
                word = ntohs(in6.s6_addr16[i]);
                hi = word >> 8;
                lo = word & 0xff;
                if (hi) {
                        if (hi > 0x0f)
                                p = hex_byte_pack(p, hi);
                        else
                                *p++ = hex_asc_lo(hi);
                        p = hex_byte_pack(p, lo);
                }
                else if (lo > 0x0f)
                        p = hex_byte_pack(p, lo);
                else
                        *p++ = hex_asc_lo(lo);
                needcolon = true;
        }

        if (useIPv4) {
                if (needcolon)
                        *p++ = ':';
                p = ip4_string(p, &in6.s6_addr[12], "I4");
        }
        *p = '\0';

        return p;
}

static noinline_for_stack
char *ip6_string(char *p, const char *addr, const char *fmt)
{
        int i;

        for (i = 0; i < 8; i++) {
                p = hex_byte_pack(p, *addr++);
                p = hex_byte_pack(p, *addr++);
                if (fmt[0] == 'I' && i != 7)
                        *p++ = ':';
        }
        *p = '\0';

        return p;
}

static noinline_for_stack
char *ip6_addr_string(char *buf, char *end, const u8 *addr,
                      struct printf_spec spec, const char *fmt)
{
        char ip6_addr[sizeof("xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255")];

        if (fmt[0] == 'I' && fmt[2] == 'c')
                ip6_compressed_string(ip6_addr, addr);
        else
                ip6_string(ip6_addr, addr, fmt);

        return string(buf, end, ip6_addr, spec);
}

static noinline_for_stack
char *ip4_addr_string(char *buf, char *end, const u8 *addr,
                      struct printf_spec spec, const char *fmt)
{
        char ip4_addr[sizeof("255.255.255.255")];

        ip4_string(ip4_addr, addr, fmt);

        return string(buf, end, ip4_addr, spec);
}

static noinline_for_stack
char *ip6_addr_string_sa(char *buf, char *end, const struct sockaddr_in6 *sa,
                         struct printf_spec spec, const char *fmt)
{
        bool have_p = false, have_s = false, have_f = false, have_c = false;
        char ip6_addr[sizeof("[xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255]") +
                      sizeof(":12345") + sizeof("/123456789") +
                      sizeof("%1234567890")];
        char *p = ip6_addr, *pend = ip6_addr + sizeof(ip6_addr);
        const u8 *addr = (const u8 *) &sa->sin6_addr;
        char fmt6[2] = { fmt[0], '6' };
        u8 off = 0;

        fmt++;
        while (isalpha(*++fmt)) {
                switch (*fmt) {
                case 'p':
                        have_p = true;
                        break;
                case 'f':
                        have_f = true;
                        break;
                case 's':
                        have_s = true;
                        break;
                case 'c':
                        have_c = true;
                        break;
                }
        }

        if (have_p || have_s || have_f) {
                *p = '[';
                off = 1;
        }

        if (fmt6[0] == 'I' && have_c)
                p = ip6_compressed_string(ip6_addr + off, addr);
        else
                p = ip6_string(ip6_addr + off, addr, fmt6);

        if (have_p || have_s || have_f)
                *p++ = ']';

        if (have_p) {
                *p++ = ':';
                p = number(p, pend, ntohs(sa->sin6_port), spec);
        }
        if (have_f) {
                *p++ = '/';
                p = number(p, pend, ntohl(sa->sin6_flowinfo &
                                          IPV6_FLOWINFO_MASK), spec);
        }
        if (have_s) {
                *p++ = '%';
                p = number(p, pend, sa->sin6_scope_id, spec);
        }
        *p = '\0';

        return string(buf, end, ip6_addr, spec);
}

static noinline_for_stack
char *ip4_addr_string_sa(char *buf, char *end, const struct sockaddr_in *sa,
                         struct printf_spec spec, const char *fmt)
{
        bool have_p = false;
        char *p, ip4_addr[sizeof("255.255.255.255") + sizeof(":12345")];
        char *pend = ip4_addr + sizeof(ip4_addr);
        const u8 *addr = (const u8 *) &sa->sin_addr.s_addr;
        char fmt4[3] = { fmt[0], '4', 0 };

        fmt++;
        while (isalpha(*++fmt)) {
                switch (*fmt) {
                case 'p':
                        have_p = true;
                        break;
                case 'h':
                case 'l':
                case 'n':
                case 'b':
                        fmt4[2] = *fmt;
                        break;
                }
        }

        p = ip4_string(ip4_addr, addr, fmt4);
        if (have_p) {
                *p++ = ':';
                p = number(p, pend, ntohs(sa->sin_port), spec);
        }
        *p = '\0';

        return string(buf, end, ip4_addr, spec);
}

static noinline_for_stack
char *uuid_string(char *buf, char *end, const u8 *addr,
                  struct printf_spec spec, const char *fmt)
{
        char uuid[sizeof("xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx")];
        char *p = uuid;
        int i;
        static const u8 be[16] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
        static const u8 le[16] = {3,2,1,0,5,4,7,6,8,9,10,11,12,13,14,15};
        const u8 *index = be;
        bool uc = false;

        switch (*(++fmt)) {
        case 'L':
                uc = true;              /* fall-through */
        case 'l':
                index = le;
                break;
        case 'B':
                uc = true;
                break;
        }

        for (i = 0; i < 16; i++) {
                p = hex_byte_pack(p, addr[index[i]]);
                switch (i) {
                case 3:
                case 5:
                case 7:
                case 9:
                        *p++ = '-';
                        break;
                }
        }

        *p = 0;

        if (uc) {
                p = uuid;
                do {
                        *p = toupper(*p);
                } while (*(++p));
        }

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

static
char *netdev_feature_string(char *buf, char *end, const u8 *addr,
                      struct printf_spec spec)
{
        spec.flags |= SPECIAL | SMALL | ZEROPAD;
        if (spec.field_width == -1)
                spec.field_width = 2 + 2 * sizeof(netdev_features_t);
        spec.base = 16;

        return number(buf, end, *(const netdev_features_t *)addr, spec);
}

static noinline_for_stack
char *address_val(char *buf, char *end, const void *addr,
                  struct printf_spec spec, const char *fmt)
{
        unsigned long long num;

        spec.flags |= SPECIAL | SMALL | ZEROPAD;
        spec.base = 16;

        switch (fmt[1]) {
        case 'd':
                num = *(const dma_addr_t *)addr;
                spec.field_width = sizeof(dma_addr_t) * 2 + 2;
                break;
        case 'p':
        default:
                num = *(const phys_addr_t *)addr;
                spec.field_width = sizeof(phys_addr_t) * 2 + 2;
                break;
        }

        return number(buf, end, num, spec);
}

int kptr_restrict __read_mostly;

/*
 * 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 handle:
 *
 * - 'F' For symbolic function descriptor pointers with offset
 * - 'f' For simple symbolic function names without offset
 * - 'S' For symbolic direct pointers with offset
 * - 's' For symbolic direct pointers without offset
 * - '[FfSs]R' as above with __builtin_extract_return_addr() translation
 * - 'B' For backtraced symbolic direct pointers with offset
 * - 'R' For decoded struct resource, e.g., [mem 0x0-0x1f 64bit pref]
 * - 'r' For raw struct resource, e.g., [mem 0x0-0x1f flags 0x201]
 * - 'M' For a 6-byte MAC address, it prints the address in the
 *       usual colon-separated hex notation
 * - 'm' For a 6-byte MAC address, it prints the hex address without colons
 * - 'MF' For a 6-byte MAC FDDI address, it prints the address
 *       with a dash-separated hex notation
 * - '[mM]R' For a 6-byte MAC address, Reverse order (Bluetooth)
 * - 'I' [46] for IPv4/IPv6 addresses printed in the usual way
 *       IPv4 uses dot-separated decimal without leading 0's (1.2.3.4)
 *       IPv6 uses colon separated network-order 16 bit hex with leading 0's
 *       [S][pfs]
 *       Generic IPv4/IPv6 address (struct sockaddr *) that falls back to
 *       [4] or [6] and is able to print port [p], flowinfo [f], scope [s]
 * - 'i' [46] for 'raw' IPv4/IPv6 addresses
 *       IPv6 omits the colons (01020304...0f)
 *       IPv4 uses dot-separated decimal with leading 0's (010.123.045.006)
 *       [S][pfs]
 *       Generic IPv4/IPv6 address (struct sockaddr *) that falls back to
 *       [4] or [6] and is able to print port [p], flowinfo [f], scope [s]
 * - '[Ii][4S][hnbl]' IPv4 addresses in host, network, big or little endian order
 * - 'I[6S]c' for IPv6 addresses printed as specified by
 *       http://tools.ietf.org/html/rfc5952
 * - 'U' For a 16 byte UUID/GUID, it prints the UUID/GUID in the form
 *       "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
 *       Options for %pU are:
 *         b big endian lower case hex (default)
 *         B big endian UPPER case hex
 *         l little endian lower case hex
 *         L little endian UPPER case hex
 *           big endian output byte order is:
 *             [0][1][2][3]-[4][5]-[6][7]-[8][9]-[10][11][12][13][14][15]
 *           little endian output byte order is:
 *             [3][2][1][0]-[5][4]-[7][6]-[8][9]-[10][11][12][13][14][15]
 * - 'V' For a struct va_format which contains a format string * and va_list *,
 *       call vsnprintf(->format, *->va_list).
 *       Implements a "recursive vsnprintf".
 *       Do not use this feature without some mechanism to verify the
 *       correctness of the format string and va_list arguments.
 * - 'K' For a kernel pointer that should be hidden from unprivileged users
 * - 'NF' For a netdev_features_t
 * - 'h[CDN]' For a variable-length buffer, it prints it as a hex string with
 *            a certain separator (' ' by default):
 *              C colon
 *              D dash
 *              N no separator
 *            The maximum supported length is 64 bytes of the input. Consider
 *            to use print_hex_dump() for the larger input.
 * - 'a[pd]' For address types [p] phys_addr_t, [d] dma_addr_t and derivatives
 *           (default assumed to be phys_addr_t, passed by reference)
 * - 'd[234]' For a dentry name (optionally 2-4 last components)
 * - 'D[234]' Same as 'd' but for a struct file
 *
 * Note: The difference between 'S' and 'F' is that on ia64 and ppc64
 * function pointers are really function descriptors, which contain a
 * pointer to the real address.
 */
static noinline_for_stack
char *pointer(const char *fmt, char *buf, char *end, void *ptr,
              struct printf_spec spec)
{
        int default_width = 2 * sizeof(void *) + (spec.flags & SPECIAL ? 2 : 0);

        if (!ptr && *fmt != 'K') {
                /*
                 * Print (null) with the same width as a pointer so it makes
                 * tabular output look nice.
                 */
                if (spec.field_width == -1)
                        spec.field_width = default_width;
                return string(buf, end, "(null)", spec);
        }

        switch (*fmt) {
        case 'F':
        case 'f':
                ptr = dereference_function_descriptor(ptr);
                /* Fallthrough */
        case 'S':
        case 's':
        case 'B':
                return symbol_string(buf, end, ptr, spec, fmt);
        case 'R':
        case 'r':
                return resource_string(buf, end, ptr, spec, fmt);
        case 'h':
                return hex_string(buf, end, ptr, spec, fmt);
        case 'M':                       /* Colon separated: 00:01:02:03:04:05 */
        case 'm':                       /* Contiguous: 000102030405 */
                                        /* [mM]F (FDDI) */
                                        /* [mM]R (Reverse order; Bluetooth) */
                return mac_address_string(buf, end, ptr, spec, fmt);
        case 'I':                       /* Formatted IP supported
                                         * 4:   1.2.3.4
                                         * 6:   0001:0203:...:0708
                                         * 6c:  1::708 or 1::1.2.3.4
                                         */
        case 'i':                       /* Contiguous:
                                         * 4:   001.002.003.004
                                         * 6:   000102...0f
                                         */
                switch (fmt[1]) {
                case '6':
                        return ip6_addr_string(buf, end, ptr, spec, fmt);
                case '4':
                        return ip4_addr_string(buf, end, ptr, spec, fmt);
                case 'S': {
                        const union {
                                struct sockaddr         raw;
                                struct sockaddr_in      v4;
                                struct sockaddr_in6     v6;
                        } *sa = ptr;

                        switch (sa->raw.sa_family) {
                        case AF_INET:
                                return ip4_addr_string_sa(buf, end, &sa->v4, spec, fmt);
                        case AF_INET6:
                                return ip6_addr_string_sa(buf, end, &sa->v6, spec, fmt);
                        default:
                                return string(buf, end, "(invalid address)", spec);
                        }}
                }
                break;
        case 'U':
                return uuid_string(buf, end, ptr, spec, fmt);
        case 'V':
                {
                        va_list va;

                        va_copy(va, *((struct va_format *)ptr)->va);
                        buf += vsnprintf(buf, end > buf ? end - buf : 0,
                                         ((struct va_format *)ptr)->fmt, va);
                        va_end(va);
                        return buf;
                }
        case 'K':
                /*
                 * %pK cannot be used in IRQ context because its test
                 * for CAP_SYSLOG would be meaningless.
                 */
                if (kptr_restrict && (in_irq() || in_serving_softirq() ||
                                      in_nmi())) {
                        if (spec.field_width == -1)
                                spec.field_width = default_width;
                        return string(buf, end, "pK-error", spec);
                }

                switch (kptr_restrict) {
                case 0:
                        /* Always print %pK values */
                        break;
                case 1: {
                        /*
                         * Only print the real pointer value if the current
                         * process has CAP_SYSLOG and is running with the
                         * same credentials it started with. This is because
                         * access to files is checked at open() time, but %pK
                         * checks permission at read() time. We don't want to
                         * leak pointer values if a binary opens a file using
                         * %pK and then elevates privileges before reading it.
                         */
                        const struct cred *cred = current_cred();

                        if (!has_capability_noaudit(current, CAP_SYSLOG) ||
                            !uid_eq(cred->euid, cred->uid) ||
                            !gid_eq(cred->egid, cred->gid))
                                ptr = NULL;
                        break;
                }
                case 2:
                default:
                        /* Always print 0's for %pK */
                        ptr = NULL;
                        break;
                }
                break;

        case 'N':
                switch (fmt[1]) {
                case 'F':
                        return netdev_feature_string(buf, end, ptr, spec);
                }
                break;
        case 'a':
                return address_val(buf, end, ptr, spec, fmt);
        case 'd':
                return dentry_name(buf, end, ptr, spec, fmt);
        case 'D':
                return dentry_name(buf, end,
                                   ((const struct file *)ptr)->f_path.dentry,
                                   spec, fmt);
        }
        spec.flags |= SMALL;
        if (spec.field_width == -1) {
                spec.field_width = default_width;
                spec.flags |= ZEROPAD;
        }
        spec.base = 16;

        return number(buf, end, (unsigned long) ptr, spec);
}

/*
 * Helper function to decode printf style format.
 * Each call decode a token from the format and return the
 * number of characters read (or likely the delta where it wants
 * to go on the next call).
 * The decoded token is returned through the parameters
 *
 * '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
 *
 * @fmt: the format string
 * @type of the token returned
 * @flags: various flags such as +, -, # tokens..
 * @field_width: overwritten width
 * @base: base of the number (octal, hex, ...)
 * @precision: precision of a number
 * @qualifier: qualifier of a number (long, size_t, ...)
 */
static noinline_for_stack
int format_decode(const char *fmt, struct printf_spec *spec)
{
        const char *start = fmt;

        /* we finished early by reading the field width */
        if (spec->type == FORMAT_TYPE_WIDTH) {
                if (spec->field_width < 0) {
                        spec->field_width = -spec->field_width;
                        spec->flags |= LEFT;
                }
                spec->type = FORMAT_TYPE_NONE;
                goto precision;
        }

        /* we finished early by reading the precision */
        if (spec->type == FORMAT_TYPE_PRECISION) {
                if (spec->precision < 0)
                        spec->precision = 0;

                spec->type = FORMAT_TYPE_NONE;
                goto qualifier;
        }

        /* By default */
        spec->type = FORMAT_TYPE_NONE;

        for (; *fmt ; ++fmt) {
                if (*fmt == '%')
                        break;
        }

        /* Return the current non-format string */
        if (fmt != start || !*fmt)
                return fmt - start;

        /* Process flags */
        spec->flags = 0;

        while (1) { /* this also skips first '%' */
                bool found = true;

                ++fmt;

                switch (*fmt) {
                case '-': spec->flags |= LEFT;    break;
                case '+': spec->flags |= PLUS;    break;
                case ' ': spec->flags |= SPACE;   break;
                case '#': spec->flags |= SPECIAL; break;
                case '0': spec->flags |= ZEROPAD; break;
                default:  found = false;
                }

                if (!found)
                        break;
        }

        /* get field width */
        spec->field_width = -1;

        if (isdigit(*fmt))
                spec->field_width = skip_atoi(&fmt);
        else if (*fmt == '*') {
                /* it's the next argument */
                spec->type = FORMAT_TYPE_WIDTH;
                return ++fmt - start;
        }

precision:
        /* get the precision */
        spec->precision = -1;
        if (*fmt == '.') {
                ++fmt;
                if (isdigit(*fmt)) {
                        spec->precision = skip_atoi(&fmt);
                        if (spec->precision < 0)
                                spec->precision = 0;
                } else if (*fmt == '*') {
                        /* it's the next argument */
                        spec->type = FORMAT_TYPE_PRECISION;
                        return ++fmt - start;
                }
        }

qualifier:
        /* get the conversion qualifier */
        spec->qualifier = -1;
        if (*fmt == 'h' || _tolower(*fmt) == 'l' ||
            _tolower(*fmt) == 'z' || *fmt == 't') {
                spec->qualifier = *fmt++;
                if (unlikely(spec->qualifier == *fmt)) {
                        if (spec->qualifier == 'l') {
                                spec->qualifier = 'L';
                                ++fmt;
                        } else if (spec->qualifier == 'h') {
                                spec->qualifier = 'H';
                                ++fmt;
                        }
                }
        }

        /* default base */
        spec->base = 10;
        switch (*fmt) {
        case 'c':
                spec->type = FORMAT_TYPE_CHAR;
                return ++fmt - start;

        case 's':
                spec->type = FORMAT_TYPE_STR;
                return ++fmt - start;

        case 'p':
                spec->type = FORMAT_TYPE_PTR;
                return fmt - start;
                /* skip alnum */

        case '%':
                spec->type = FORMAT_TYPE_PERCENT_CHAR;
                return ++fmt - start;

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

        case 'x':
                spec->flags |= SMALL;

        case 'X':
                spec->base = 16;
                break;

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

        case 'n':
                /*
                 * Since %n poses a greater security risk than utility, treat
                 * it as an invalid format specifier. Warn about its use so
                 * that new instances don't get added.
                 */
                WARN_ONCE(1, "Please remove ignored %%n in '%s'\n", fmt);
                /* Fall-through */

        default:
                spec->type = FORMAT_TYPE_INVALID;
                return fmt - start;
        }

        if (spec->qualifier == 'L')
                spec->type = FORMAT_TYPE_LONG_LONG;
        else if (spec->qualifier == 'l') {
                if (spec->flags & SIGN)
                        spec->type = FORMAT_TYPE_LONG;
                else
                        spec->type = FORMAT_TYPE_ULONG;
        } else if (_tolower(spec->qualifier) == 'z') {
                spec->type = FORMAT_TYPE_SIZE_T;
        } else if (spec->qualifier == 't') {
                spec->type = FORMAT_TYPE_PTRDIFF;
        } else if (spec->qualifier == 'H') {
                if (spec->flags & SIGN)
                        spec->type = FORMAT_TYPE_BYTE;
                else
                        spec->type = FORMAT_TYPE_UBYTE;
        } else if (spec->qualifier == 'h') {
                if (spec->flags & SIGN)
                        spec->type = FORMAT_TYPE_SHORT;
                else
                        spec->type = FORMAT_TYPE_USHORT;
        } else {
                if (spec->flags & SIGN)
                        spec->type = FORMAT_TYPE_INT;
                else
                        spec->type = FORMAT_TYPE_UINT;
        }

        return ++fmt - start;
}

/**
 * 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
 *
 * This function follows C99 vsnprintf, but has some extensions:
 * %pS output the name of a text symbol with offset
 * %ps output the name of a text symbol without offset
 * %pF output the name of a function pointer with its offset
 * %pf output the name of a function pointer without its offset
 * %pB output the name of a backtrace symbol with its offset
 * %pR output the address range in a struct resource with decoded flags
 * %pr output the address range in a struct resource with raw flags
 * %pM output a 6-byte MAC address with colons
 * %pMR output a 6-byte MAC address with colons in reversed order
 * %pMF output a 6-byte MAC address with dashes
 * %pm output a 6-byte MAC address without colons
 * %pmR output a 6-byte MAC address without colons in reversed order
 * %pI4 print an IPv4 address without leading zeros
 * %pi4 print an IPv4 address with leading zeros
 * %pI6 print an IPv6 address with colons
 * %pi6 print an IPv6 address without colons
 * %pI6c print an IPv6 address as specified by RFC 5952
 * %pIS depending on sa_family of 'struct sockaddr *' print IPv4/IPv6 address
 * %piS depending on sa_family of 'struct sockaddr *' print IPv4/IPv6 address
 * %pU[bBlL] print a UUID/GUID in big or little endian using lower or upper
 *   case.
 * %*ph[CDN] a variable-length hex string with a separator (supports up to 64
 *           bytes of the input)
 * %n is ignored
 *
 * ** Please update Documentation/printk-formats.txt when making changes **
 *
 * 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.
 *
 * If you're not already dealing with a va_list consider using snprintf().
 */
int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
{
        unsigned long long num;
        char *str, *end;
        struct printf_spec spec = {0};

        /* Reject out-of-range values early.  Large positive sizes are
           used for unknown buffer sizes. */
        if (WARN_ON_ONCE((int) size < 0))
                return 0;

        str = buf;
        end = buf + size;

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

        while (*fmt) {
                const char *old_fmt = fmt;
                int read = format_decode(fmt, &spec);

                fmt += read;

                switch (spec.type) {
                case FORMAT_TYPE_NONE: {
                        int copy = read;
                        if (str < end) {
                                if (copy > end - str)
                                        copy = end - str;
                                memcpy(str, old_fmt, copy);
                        }
                        str += read;
                        break;
                }

                case FORMAT_TYPE_WIDTH:
                        spec.field_width = va_arg(args, int);
                        break;

                case FORMAT_TYPE_PRECISION:
                        spec.precision = va_arg(args, int);
                        break;

                case FORMAT_TYPE_CHAR: {
                        char c;

                        if (!(spec.flags & LEFT)) {
                                while (--spec.field_width > 0) {
                                        if (str < end)
                                                *str = ' ';
                                        ++str;

                                }
                        }
                        c = (unsigned char) va_arg(args, int);
                        if (str < end)
                                *str = c;
                        ++str;
                        while (--spec.field_width > 0) {
                                if (str < end)
                                        *str = ' ';
                                ++str;
                        }
                        break;
                }

                case FORMAT_TYPE_STR:
                        str = string(str, end, va_arg(args, char *), spec);
                        break;

                case FORMAT_TYPE_PTR:
                        str = pointer(fmt+1, str, end, va_arg(args, void *),
                                      spec);
                        while (isalnum(*fmt))
                                fmt++;
                        break;

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

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

                default:
                        switch (spec.type) {
                        case FORMAT_TYPE_LONG_LONG:
                                num = va_arg(args, long long);
                                break;
                        case FORMAT_TYPE_ULONG:
                                num = va_arg(args, unsigned long);
                                break;
                        case FORMAT_TYPE_LONG:
                                num = va_arg(args, long);
                                break;
                        case FORMAT_TYPE_SIZE_T:
                                if (spec.flags & SIGN)
                                        num = va_arg(args, ssize_t);
                                else
                                        num = va_arg(args, size_t);
                                break;
                        case FORMAT_TYPE_PTRDIFF:
                                num = va_arg(args, ptrdiff_t);
                                break;
                        case FORMAT_TYPE_UBYTE:
                                num = (unsigned char) va_arg(args, int);
                                break;
                        case FORMAT_TYPE_BYTE:
                                num = (signed char) va_arg(args, int);
                                break;
                        case FORMAT_TYPE_USHORT:
                                num = (unsigned short) va_arg(args, int);
                                break;
                        case FORMAT_TYPE_SHORT:
                                num = (short) va_arg(args, int);
                                break;
                        case FORMAT_TYPE_INT:
                                num = (int) va_arg(args, int);
                                break;
                        default:
                                num = va_arg(args, unsigned int);
                        }

                        str = number(str, end, num, spec);
                }
        }

        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.
 *
 * If you're not already dealing with a va_list consider using scnprintf().
 *
 * See the vsnprintf() documentation for format string extensions over C99.
 */
int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
{
        int i;

        i = vsnprintf(buf, size, fmt, args);

        if (likely(i < size))
                return i;
        if (size != 0)
                return size - 1;
        return 0;
}
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.
 *
 * See the vsnprintf() documentation for format string extensions over C99.
 */
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 = vscnprintf(buf, size, fmt, args);
        va_end(args);

        return 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.
 *
 * If you're not already dealing with a va_list consider using sprintf().
 *
 * See the vsnprintf() documentation for format string extensions over C99.
 */
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.
 *
 * See the vsnprintf() documentation for format string extensions over C99.
 */
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);

#ifdef CONFIG_BINARY_PRINTF
/*
 * bprintf service:
 * vbin_printf() - VA arguments to binary data
 * bstr_printf() - Binary data to text string
 */

/**
 * vbin_printf - Parse a format string and place args' binary value in a buffer
 * @bin_buf: The buffer to place args' binary value
 * @size: The size of the buffer(by words(32bits), not characters)
 * @fmt: The format string to use
 * @args: Arguments for the format string
 *
 * The format follows C99 vsnprintf, except %n is ignored, and its argument
 * is skiped.
 *
 * The return value is the number of words(32bits) which would be generated for
 * the given input.
 *
 * NOTE:
 * If the return value is greater than @size, the resulting bin_buf is NOT
 * valid for bstr_printf().
 */
int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args)
{
        struct printf_spec spec = {0};
        char *str, *end;

        str = (char *)bin_buf;
        end = (char *)(bin_buf + size);

#define save_arg(type)                                                  \
do {                                                                    \
        if (sizeof(type) == 8) {                                        \
                unsigned long long value;                               \
                str = PTR_ALIGN(str, sizeof(u32));                      \
                value = va_arg(args, unsigned long long);               \
                if (str + sizeof(type) <= end) {                        \
                        *(u32 *)str = *(u32 *)&value;                   \
                        *(u32 *)(str + 4) = *((u32 *)&value + 1);       \
                }                                                       \
        } else {                                                        \
                unsigned long value;                                    \
                str = PTR_ALIGN(str, sizeof(type));                     \
                value = va_arg(args, int);                              \
                if (str + sizeof(type) <= end)                          \
                        *(typeof(type) *)str = (type)value;             \
        }                                                               \
        str += sizeof(type);                                            \
} while (0)

        while (*fmt) {
                int read = format_decode(fmt, &spec);

                fmt += read;

                switch (spec.type) {
                case FORMAT_TYPE_NONE:
                case FORMAT_TYPE_INVALID:
                case FORMAT_TYPE_PERCENT_CHAR:
                        break;

                case FORMAT_TYPE_WIDTH:
                case FORMAT_TYPE_PRECISION:
                        save_arg(int);
                        break;

                case FORMAT_TYPE_CHAR:
                        save_arg(char);
                        break;

                case FORMAT_TYPE_STR: {
                        const char *save_str = va_arg(args, char *);
                        size_t len;

                        if ((unsigned long)save_str > (unsigned long)-PAGE_SIZE
                                        || (unsigned long)save_str < PAGE_SIZE)
                                save_str = "(null)";
                        len = strlen(save_str) + 1;
                        if (str + len < end)
                                memcpy(str, save_str, len);
                        str += len;
                        break;
                }

                case FORMAT_TYPE_PTR:
                        save_arg(void *);
                        /* skip all alphanumeric pointer suffixes */
                        while (isalnum(*fmt))
                                fmt++;
                        break;

                default:
                        switch (spec.type) {

                        case FORMAT_TYPE_LONG_LONG:
                                save_arg(long long);
                                break;
                        case FORMAT_TYPE_ULONG:
                        case FORMAT_TYPE_LONG:
                                save_arg(unsigned long);
                                break;
                        case FORMAT_TYPE_SIZE_T:
                                save_arg(size_t);
                                break;
                        case FORMAT_TYPE_PTRDIFF:
                                save_arg(ptrdiff_t);
                                break;
                        case FORMAT_TYPE_UBYTE:
                        case FORMAT_TYPE_BYTE:
                                save_arg(char);
                                break;
                        case FORMAT_TYPE_USHORT:
                        case FORMAT_TYPE_SHORT:
                                save_arg(short);
                                break;
                        default:
                                save_arg(int);
                        }
                }
        }

        return (u32 *)(PTR_ALIGN(str, sizeof(u32))) - bin_buf;
#undef save_arg
}
EXPORT_SYMBOL_GPL(vbin_printf);

/**
 * bstr_printf - Format a string from binary arguments 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
 * @bin_buf: Binary arguments for the format string
 *
 * This function like C99 vsnprintf, but the difference is that vsnprintf gets
 * arguments from stack, and bstr_printf gets arguments from @bin_buf which is
 * a binary buffer that generated by vbin_printf.
 *
 * The format follows C99 vsnprintf, but has some extensions:
 *  see vsnprintf comment for details.
 *
 * 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.
 */
int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf)
{
        struct printf_spec spec = {0};
        char *str, *end;
        const char *args = (const char *)bin_buf;

        if (WARN_ON_ONCE((int) size < 0))
                return 0;

        str = buf;
        end = buf + size;

#define get_arg(type)                                                   \
({                                                                      \
        typeof(type) value;                                             \
        if (sizeof(type) == 8) {                                        \
                args = PTR_ALIGN(args, sizeof(u32));                    \
                *(u32 *)&value = *(u32 *)args;                          \
                *((u32 *)&value + 1) = *(u32 *)(args + 4);              \
        } else {                                                        \
                args = PTR_ALIGN(args, sizeof(type));                   \
                value = *(typeof(type) *)args;                          \
        }                                                               \
        args += sizeof(type);                                           \
        value;                                                          \
})

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

        while (*fmt) {
                const char *old_fmt = fmt;
                int read = format_decode(fmt, &spec);

                fmt += read;

                switch (spec.type) {
                case FORMAT_TYPE_NONE: {
                        int copy = read;
                        if (str < end) {
                                if (copy > end - str)
                                        copy = end - str;
                                memcpy(str, old_fmt, copy);
                        }
                        str += read;
                        break;
                }

                case FORMAT_TYPE_WIDTH:
                        spec.field_width = get_arg(int);
                        break;

                case FORMAT_TYPE_PRECISION:
                        spec.precision = get_arg(int);
                        break;

                case FORMAT_TYPE_CHAR: {
                        char c;

                        if (!(spec.flags & LEFT)) {
                                while (--spec.field_width > 0) {
                                        if (str < end)
                                                *str = ' ';
                                        ++str;
                                }
                        }
                        c = (unsigned char) get_arg(char);
                        if (str < end)
                                *str = c;
                        ++str;
                        while (--spec.field_width > 0) {
                                if (str < end)
                                        *str = ' ';
                                ++str;
                        }
                        break;
                }

                case FORMAT_TYPE_STR: {
                        const char *str_arg = args;
                        args += strlen(str_arg) + 1;
                        str = string(str, end, (char *)str_arg, spec);
                        break;
                }

                case FORMAT_TYPE_PTR:
                        str = pointer(fmt+1, str, end, get_arg(void *), spec);
                        while (isalnum(*fmt))
                                fmt++;
                        break;

                case FORMAT_TYPE_PERCENT_CHAR:
                case FORMAT_TYPE_INVALID:
                        if (str < end)
                                *str = '%';
                        ++str;
                        break;

                default: {
                        unsigned long long num;

                        switch (spec.type) {

                        case FORMAT_TYPE_LONG_LONG:
                                num = get_arg(long long);
                                break;
                        case FORMAT_TYPE_ULONG:
                        case FORMAT_TYPE_LONG:
                                num = get_arg(unsigned long);
                                break;
                        case FORMAT_TYPE_SIZE_T:
                                num = get_arg(size_t);
                                break;
                        case FORMAT_TYPE_PTRDIFF:
                                num = get_arg(ptrdiff_t);
                                break;
                        case FORMAT_TYPE_UBYTE:
                                num = get_arg(unsigned char);
                                break;
                        case FORMAT_TYPE_BYTE:
                                num = get_arg(signed char);
                                break;
                        case FORMAT_TYPE_USHORT:
                                num = get_arg(unsigned short);
                                break;
                        case FORMAT_TYPE_SHORT:
                                num = get_arg(short);
                                break;
                        case FORMAT_TYPE_UINT:
                                num = get_arg(unsigned int);
                                break;
                        default:
                                num = get_arg(int);
                        }

                        str = number(str, end, num, spec);
                } /* default: */
                } /* switch(spec.type) */
        } /* while(*fmt) */

        if (size > 0) {
                if (str < end)
                        *str = '\0';
                else
                        end[-1] = '\0';
        }

#undef get_arg

        /* the trailing null byte doesn't count towards the total */
        return str - buf;
}
EXPORT_SYMBOL_GPL(bstr_printf);

/**
 * bprintf - Parse a format string and place args' binary value in a buffer
 * @bin_buf: The buffer to place args' binary value
 * @size: The size of the buffer(by words(32bits), not characters)
 * @fmt: The format string to use
 * @...: Arguments for the format string
 *
 * The function returns the number of words(u32) written
 * into @bin_buf.
 */
int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...)
{
        va_list args;
        int ret;

        va_start(args, fmt);
        ret = vbin_printf(bin_buf, size, fmt, args);
        va_end(args);

        return ret;
}
EXPORT_SYMBOL_GPL(bprintf);

#endif /* CONFIG_BINARY_PRINTF */

/**
 * 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;
        u8 qualifier;
        unsigned int base;
        union {
                long long s;
                unsigned long long u;
        } val;
        s16 field_width;
        bool is_sign;

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

                /* get field width */
                field_width = -1;
                if (isdigit(*fmt)) {
                        field_width = skip_atoi(&fmt);
                        if (field_width <= 0)
                                break;
                }

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

                if (!*fmt)
                        break;

                if (*fmt == 'n') {
                        /* return number of characters read so far */
                        *va_arg(args, int *) = str - buf;
                        ++fmt;
                        continue;
                }

                if (!*str)
                        break;

                base = 10;
                is_sign = false;

                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 = SHRT_MAX;
                        /* first, skip leading white space in buffer */
                        str = skip_spaces(str);

                        /* now copy until next white space */
                        while (*str && !isspace(*str) && field_width--)
                                *s++ = *str++;
                        *s = '\0';
                        num++;
                }
                continue;
                case 'o':
                        base = 8;
                        break;
                case 'x':
                case 'X':
                        base = 16;
                        break;
                case 'i':
                        base = 0;
                case 'd':
                        is_sign = true;
                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.
                 */
                str = skip_spaces(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;

                if (is_sign)
                        val.s = qualifier != 'L' ?
                                simple_strtol(str, &next, base) :
                                simple_strtoll(str, &next, base);
                else
                        val.u = qualifier != 'L' ?
                                simple_strtoul(str, &next, base) :
                                simple_strtoull(str, &next, base);

                if (field_width > 0 && next - str > field_width) {
                        if (base == 0)
                                _parse_integer_fixup_radix(str, &base);
                        while (next - str > field_width) {
                                if (is_sign)
                                        val.s = div_s64(val.s, base);
                                else
                                        val.u = div_u64(val.u, base);
                                --next;
                        }
                }

                switch (qualifier) {
                case 'H':       /* that's 'hh' in format */
                        if (is_sign)
                                *va_arg(args, signed char *) = val.s;
                        else
                                *va_arg(args, unsigned char *) = val.u;
                        break;
                case 'h':
                        if (is_sign)
                                *va_arg(args, short *) = val.s;
                        else
                                *va_arg(args, unsigned short *) = val.u;
                        break;
                case 'l':
                        if (is_sign)
                                *va_arg(args, long *) = val.s;
                        else
                                *va_arg(args, unsigned long *) = val.u;
                        break;
                case 'L':
                        if (is_sign)
                                *va_arg(args, long long *) = val.s;
                        else
                                *va_arg(args, unsigned long long *) = val.u;
                        break;
                case 'Z':
                case 'z':
                        *va_arg(args, size_t *) = val.u;
                        break;
                default:
                        if (is_sign)
                                *va_arg(args, int *) = val.s;
                        else
                                *va_arg(args, unsigned int *) = val.u;
                        break;
                }
                num++;

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

        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);