vsprintf.c

/*
 * Copyright (c) 2008-2014, Pedigree Developers
 *
 * Please see the CONTRIB file in the root of the source tree for a full
 * list of contributors.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

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

#include "pedigree/kernel/processor/types.h"
#include "pedigree/kernel/utilities/utility.h"
#include <stdarg.h>

#ifdef __clang__
#pragma GCC diagnostic ignored "-Wgnu-statement-expression"
#endif

/* we use this so that we can do without the ctype library */
#define is_digit(c) ((c) >= '0' && (c) <= '9')

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

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

#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 SPECIAL 32 /* 0x */
#define SMALL 64   /* use 'abcdef' instead of 'ABCDEF' */

#if defined(X86_COMMON) || defined(HOSTED_X86_COMMON) || defined(UTILITY_LINUX)
#define do_div(n, base)                                                       \
    ({                                                                        \
        int __res;                                                            \
        __asm__("div %4" : "=a"(n), "=d"(__res) : "0"(n), "1"(0), "r"(base)); \
        __res;                                                                \
    })
#else
#define do_div(n, base) ({ n / base; })
#endif

static char *
number(char *str, int64_t num, int base, int size, int precision, int type)
{
    char c, sign, tmp[36];
    const char *digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    int i;

    if (type & SMALL)
        digits = "0123456789abcdefghijklmnopqrstuvwxyz";
    if (type & LEFT)
        type &= ~ZEROPAD;
    if (base < 2 || base > 36)
        return 0;
    c = (type & ZEROPAD) ? '0' : ' ';
    if (type & SIGN && num < 0)
    {
        sign = '-';
        num = -num;
    }
    else
        sign = (type & PLUS) ? '+' : ((type & SPACE) ? ' ' : 0);
    if (sign)
        size--;
    if (type & SPECIAL)
    {
        if (base == 16)
            size -= 2;
        else if (base == 8)
            size--;
    }
    i = 0;
    if (num == 0)
        tmp[i++] = '0';
    else
        while (num != 0)
        {
            int d = do_div(num, base);
            tmp[i++] = digits[d];
        }
    if (i > precision)
        precision = i;
    size -= precision;
    if (!(type & (ZEROPAD + LEFT)))
        while (size-- > 0)
            *str++ = ' ';
    if (sign)
        *str++ = sign;
    if (type & SPECIAL)
    {
        if (base == 8)
            *str++ = '0';
        else if (base == 16)
        {
            *str++ = '0';
            *str++ = digits[33];
        }
    }
    if (!(type & LEFT))
        while (size-- > 0)
            *str++ = c;
    while (i < precision--)
        *str++ = '0';
    while (i-- > 0)
        *str++ = tmp[i];
    while (size-- > 0)
        *str++ = ' ';
    return str;
}

int VStringFormat(char *buf, const char *fmt, va_list args)
{
    int len;
    int i;
    char *str;
    char *s;
    int *ip;

    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 */

    for (str = buf; *fmt; ++fmt)
    {
        if (*fmt != '%')
        {
            *str++ = *fmt;
            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 (is_digit(*fmt))
            field_width = skip_atoi(&fmt);
        else if (*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 (is_digit(*fmt))
                precision = skip_atoi(&fmt);
            else if (*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')
        {
            qualifier = *fmt;
            ++fmt;
        }

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

            case 's':
                s = va_arg(args, char *);
                len = StringLength(s);
                if (precision < 0)
                    precision = len;
                else if (len > precision)
                    len = precision;

                if (!(flags & LEFT))
                    while (len < field_width--)
                        *str++ = ' ';
                for (i = 0; i < len; ++i)
                    *str++ = *s++;
                while (len < field_width--)
                    *str++ = ' ';
                break;

            case 'o':
                str = number(
                    str, va_arg(args, unsigned long), 8, field_width, precision,
                    flags);
                break;

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

            case 'x':
                flags |= SMALL;
            case 'X':
                str = number(
                    str, va_arg(args, unsigned long), 16, field_width,
                    precision, flags);
                break;

            case 'd':
            case 'i':
                flags |= SIGN;
            case 'u':
                str = number(
                    str, va_arg(args, unsigned long), 10, field_width,
                    precision, flags);
                break;

            case 'n':
                ip = va_arg(args, int *);
                *ip = (str - buf);
                break;

            default:
                if (*fmt != '%')
                    *str++ = '%';
                if (*fmt)
                    *str++ = *fmt;
                else
                    --fmt;
                break;
        }
    }
    *str = '\0';
    return str - buf;
}