printk: remove %p6 format specifier, fix up comments

[deliverable/linux.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>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/kernel.h>
#include <linux/kallsyms.h>
#include <linux/uaccess.h>
#include <linux/ioport.h>

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

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

static unsigned int simple_guess_base(const char *cp)
{
        if (cp[0] == '0') {
                if (TOLOWER(cp[1]) == 'x' && isxdigit(cp[2]))
                        return 16;
                else
                        return 8;
        } else {
                return 10;
        }
}

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

        if (!base)
                base = simple_guess_base(cp);

        if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x')
                cp += 2;

        while (isxdigit(*cp)) {
                unsigned int value;

                value = isdigit(*cp) ? *cp - '0' : TOLOWER(*cp) - 'a' + 10;
                if (value >= base)
                        break;
                result = result * base + value;
                cp++;
        }

        if (endp)
                *endp = (char *)cp;
        return result;
}
EXPORT_SYMBOL(simple_strtoul);

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

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

        if (!base)
                base = simple_guess_base(cp);

        if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x')
                cp += 2;

        while (isxdigit(*cp)) {
                unsigned int value;

                value = isdigit(*cp) ? *cp - '0' : TOLOWER(*cp) - 'a' + 10;
                if (value >= base)
                        break;
                result = result * base + value;
                cp++;
        }

        if (endp)
                *endp = (char *)cp;
        return result;
}
EXPORT_SYMBOL(simple_strtoull);

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

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

        *res = 0;
        len = strlen(cp);
        if (len == 0)
                return -EINVAL;

        val = simple_strtoul(cp, &tail, base);
        if ((*tail == '\0') ||
                ((len == (size_t)(tail - cp) + 1) && (*tail == '\n'))) {
                *res = val;
                return 0;
        }

        return -EINVAL;
}
EXPORT_SYMBOL(strict_strtoul);

/**
 * strict_strtol - convert a string to a long strictly
 * @cp: The string to be converted
 * @base: The number base to use
 * @res: The converted result value
 *
 * strict_strtol is similiar to strict_strtoul, but it allows the first
 * character of a string is '-'.
 *
 * It returns 0 if conversion is successful and *res is set to the converted
 * value, otherwise it returns -EINVAL and *res is set to 0.
 */
int strict_strtol(const char *cp, unsigned int base, long *res)
{
        int ret;
        if (*cp == '-') {
                ret = strict_strtoul(cp + 1, base, (unsigned long *)res);
                if (!ret)
                        *res = -(*res);
        } else {
                ret = strict_strtoul(cp, base, (unsigned long *)res);
        }

        return ret;
}
EXPORT_SYMBOL(strict_strtol);

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

        *res = 0;
        len = strlen(cp);
        if (len == 0)
                return -EINVAL;

        val = simple_strtoull(cp, &tail, base);
        if ((*tail == '\0') ||
                ((len == (size_t)(tail - cp) + 1) && (*tail == '\n'))) {
                *res = val;
                return 0;
        }

        return -EINVAL;
}
EXPORT_SYMBOL(strict_strtoull);

/**
 * strict_strtoll - convert a string to a long long strictly
 * @cp: The string to be converted
 * @base: The number base to use
 * @res: The converted result value
 *
 * strict_strtoll is similiar to strict_strtoull, but it allows the first
 * character of a string is '-'.
 *
 * It returns 0 if conversion is successful and *res is set to the converted
 * value, otherwise it returns -EINVAL and *res is set to 0.
 */
int strict_strtoll(const char *cp, unsigned int base, long long *res)
{
        int ret;
        if (*cp == '-') {
                ret = strict_strtoull(cp + 1, base, (unsigned long long *)res);
                if (!ret)
                        *res = -(*res);
        } else {
                ret = strict_strtoull(cp, base, (unsigned long long *)res);
        }

        return ret;
}
EXPORT_SYMBOL(strict_strtoll);

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        len = strnlen(s, precision);

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

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

static char *resource_string(char *buf, char *end, struct resource *res, int field_width, int precision, int flags)
{
#ifndef IO_RSRC_PRINTK_SIZE
#define IO_RSRC_PRINTK_SIZE     4
#endif

#ifndef MEM_RSRC_PRINTK_SIZE
#define MEM_RSRC_PRINTK_SIZE    8
#endif

        /* room for the actual numbers, the two "0x", -, [, ] and the final zero */
        char sym[4*sizeof(resource_size_t) + 8];
        char *p = sym, *pend = sym + sizeof(sym);
        int size = -1;

        if (res->flags & IORESOURCE_IO)
                size = IO_RSRC_PRINTK_SIZE;
        else if (res->flags & IORESOURCE_MEM)
                size = MEM_RSRC_PRINTK_SIZE;

        *p++ = '[';
        p = number(p, pend, res->start, 16, size, -1, SPECIAL | SMALL | ZEROPAD);
        *p++ = '-';
        p = number(p, pend, res->end, 16, size, -1, SPECIAL | SMALL | ZEROPAD);
        *p++ = ']';
        *p = 0;

        return string(buf, end, sym, field_width, precision, flags);
}

static char *mac_address_string(char *buf, char *end, u8 *addr, int field_width,
                                int precision, int flags)
{
        char mac_addr[6 * 3]; /* (6 * 2 hex digits), 5 colons and trailing zero */
        char *p = mac_addr;
        int i;

        for (i = 0; i < 6; i++) {
                p = pack_hex_byte(p, addr[i]);
                if (!(flags & SPECIAL) && i != 5)
                        *p++ = ':';
        }
        *p = '\0';

        return string(buf, end, mac_addr, field_width, precision, flags & ~SPECIAL);
}

static char *ip6_addr_string(char *buf, char *end, u8 *addr, int field_width,
                         int precision, int flags)
{
        char ip6_addr[8 * 5]; /* (8 * 4 hex digits), 7 colons and trailing zero */
        char *p = ip6_addr;
        int i;

        for (i = 0; i < 8; i++) {
                p = pack_hex_byte(p, addr[2 * i]);
                p = pack_hex_byte(p, addr[2 * i + 1]);
                if (!(flags & SPECIAL) && i != 7)
                        *p++ = ':';
        }
        *p = '\0';

        return string(buf, end, ip6_addr, field_width, precision, flags & ~SPECIAL);
}

static char *ip4_addr_string(char *buf, char *end, u8 *addr, int field_width,
                         int precision, int flags)
{
        char ip4_addr[4 * 4]; /* (4 * 3 decimal digits), 3 dots and trailing zero */
        char *p = ip4_addr;
        int i;

        for (i = 0; i < 4; i++) {
                p = put_dec_trunc(p, addr[i]);
                if (i != 3)
                        *p++ = '.';
        }
        *p = '\0';

        return string(buf, end, ip4_addr, field_width, precision, flags & ~SPECIAL);
}

/*
 * 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
 * - 'S' For symbolic direct pointers
 * - 'R' For a struct resource pointer, it prints the range of
 *       addresses (not the name nor the flags)
 * - 'M' For a 6-byte MAC address, it prints the address in the
 *       usual colon-separated hex notation
 * - 'I' [46] for IPv4/IPv6 addresses printed in the usual way (dot-separated
 *       decimal for v4 and colon separated network-order 16 bit hex for v6)
 * - 'i' [46] for 'raw' IPv4/IPv6 addresses, IPv6 omits the colons, IPv4 is
 *       currently the same
 *
 * 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 char *pointer(const char *fmt, char *buf, char *end, void *ptr, int field_width, int precision, int flags)
{
        switch (*fmt) {
        case 'F':
                ptr = dereference_function_descriptor(ptr);
                /* Fallthrough */
        case 'S':
                return symbol_string(buf, end, ptr, field_width, precision, flags);
        case 'R':
                return resource_string(buf, end, ptr, field_width, precision, flags);
        case 'M':
                return mac_address_string(buf, end, ptr, field_width, precision, flags);
        case 'i':
                flags |= SPECIAL;
                /* Fallthrough */
        case 'I':
                if (fmt[1] == '6')
                        return ip6_addr_string(buf, end, ptr, field_width, precision, flags);
                if (fmt[1] == '4')
                        return ip4_addr_string(buf, end, ptr, field_width, precision, flags);
                flags &= ~SPECIAL;
                break;
        }
        flags |= SMALL;
        if (field_width == -1) {
                field_width = 2*sizeof(void *);
                flags |= ZEROPAD;
        }
        return number(buf, end, (unsigned long) ptr, 16, field_width, precision, flags);
}

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

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

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

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

        str = buf;
        end = buf + size;

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

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

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

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

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

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

                /* default base */
                base = 10;

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

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

                        case 'p':
                                str = pointer(fmt+1, str, end,
                                                va_arg(args, void *),
                                                field_width, precision, flags);
                                /* Skip all alphanumeric pointer suffixes */
                                while (isalnum(fmt[1]))
                                        fmt++;
                                continue;

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

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

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

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

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

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

/**
 * vscnprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @size: The size of the buffer, including the trailing null space
 * @fmt: The format string to use
 * @args: Arguments for the format string
 *
 * The return value is the number of characters which have been written into
 * the @buf not including the trailing '\0'. If @size is <= 0 the function
 * returns 0.
 *
 * Call this function if you are already dealing with a va_list.
 * You probably want scnprintf() instead.
 *
 * 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);
        return (i >= size) ? (size - 1) : i;
}
EXPORT_SYMBOL(vscnprintf);

/**
 * snprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @size: The size of the buffer, including the trailing null space
 * @fmt: The format string to use
 * @...: Arguments for the format string
 *
 * The return value is the number of characters which would be
 * generated for the given input, excluding the trailing null,
 * as per ISO C99.  If the return is greater than or equal to
 * @size, the resulting string is truncated.
 *
 * 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 = vsnprintf(buf, size, fmt, args);
        va_end(args);
        return (i >= size) ? (size - 1) : i;
}
EXPORT_SYMBOL(scnprintf);

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        return num;
}
EXPORT_SYMBOL(vsscanf);

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

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