// SPDX-License-Identifier: GPL-2.0-only
#include "test_util.h"
#include "kvm_util.h"
#include "ucall_common.h"

#define APPEND_BUFFER_SAFE(str, end, v) \
do {                                    \
        GUEST_ASSERT(str < end);        \
        *str++ = (v);                   \
} while (0)

static int isdigit(int ch)
{
        return (ch >= '0') && (ch <= '9');
}

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

        while (isdigit(**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 SMALL   32              /* Must be 32 == 0x20 */
#define SPECIAL 64              /* 0x */

#define __do_div(n, base)                               \
({                                                      \
        int __res;                                      \
                                                        \
        __res = ((uint64_t) n) % (uint32_t) base;       \
        n = ((uint64_t) n) / (uint32_t) base;           \
        __res;                                          \
})

static char *number(char *str, const char *end, 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 c, sign, locase;
        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;
        if (base < 2 || base > 16)
                return NULL;
        c = (type & ZEROPAD) ? '0' : ' ';
        sign = 0;
        if (type & SIGN) {
                if (num < 0) {
                        sign = '-';
                        num = -num;
                        size--;
                } else if (type & PLUS) {
                        sign = '+';
                        size--;
                } else if (type & SPACE) {
                        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)
                        tmp[i++] = (digits[__do_div(num, base)] | locase);
        if (i > precision)
                precision = i;
        size -= precision;
        if (!(type & (ZEROPAD + LEFT)))
                while (size-- > 0)
                        APPEND_BUFFER_SAFE(str, end, ' ');
        if (sign)
                APPEND_BUFFER_SAFE(str, end, sign);
        if (type & SPECIAL) {
                if (base == 8)
                        APPEND_BUFFER_SAFE(str, end, '0');
                else if (base == 16) {
                        APPEND_BUFFER_SAFE(str, end, '0');
                        APPEND_BUFFER_SAFE(str, end, 'x');
                }
        }
        if (!(type & LEFT))
                while (size-- > 0)
                        APPEND_BUFFER_SAFE(str, end, c);
        while (i < precision--)
                APPEND_BUFFER_SAFE(str, end, '0');
        while (i-- > 0)
                APPEND_BUFFER_SAFE(str, end, tmp[i]);
        while (size-- > 0)
                APPEND_BUFFER_SAFE(str, end, ' ');

        return str;
}

int guest_vsnprintf(char *buf, int n, const char *fmt, va_list args)
{
        char *str, *end;
        const char *s;
        uint64_t num;
        int i, base;
        int len;

        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 */

        end = buf + n;
        GUEST_ASSERT(buf < end);
        GUEST_ASSERT(n > 0);

        for (str = buf; *fmt; ++fmt) {
                if (*fmt != '%') {
                        APPEND_BUFFER_SAFE(str, end, *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 (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') {
                        qualifier = *fmt;
                        ++fmt;
                }

                /*
                 * Play nice with %llu, %llx, etc.  KVM selftests only support
                 * 64-bit builds, so just treat %ll* the same as %l*.
                 */
                if (qualifier == 'l' && *fmt == 'l')
                        ++fmt;

                /* default base */
                base = 10;

                switch (*fmt) {
                case 'c':
                        if (!(flags & LEFT))
                                while (--field_width > 0)
                                        APPEND_BUFFER_SAFE(str, end, ' ');
                        APPEND_BUFFER_SAFE(str, end,
                                            (uint8_t)va_arg(args, int));
                        while (--field_width > 0)
                                APPEND_BUFFER_SAFE(str, end, ' ');
                        continue;

                case 's':
                        s = va_arg(args, char *);
                        len = strnlen(s, precision);

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

                case 'p':
                        if (field_width == -1) {
                                field_width = 2 * sizeof(void *);
                                flags |= SPECIAL | SMALL | ZEROPAD;
                        }
                        str = number(str, end,
                                     (uint64_t)va_arg(args, void *), 16,
                                     field_width, precision, flags);
                        continue;

                case 'n':
                        if (qualifier == 'l') {
                                long *ip = va_arg(args, long *);
                                *ip = (str - buf);
                        } else {
                                int *ip = va_arg(args, int *);
                                *ip = (str - buf);
                        }
                        continue;

                case '%':
                        APPEND_BUFFER_SAFE(str, end, '%');
                        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:
                        APPEND_BUFFER_SAFE(str, end, '%');
                        if (*fmt)
                                APPEND_BUFFER_SAFE(str, end, *fmt);
                        else
                                --fmt;
                        continue;
                }
                if (qualifier == 'l')
                        num = va_arg(args, uint64_t);
                else if (qualifier == 'h') {
                        num = (uint16_t)va_arg(args, int);
                        if (flags & SIGN)
                                num = (int16_t)num;
                } else if (flags & SIGN)
                        num = va_arg(args, int);
                else
                        num = va_arg(args, uint32_t);
                str = number(str, end, num, base, field_width, precision, flags);
        }

        GUEST_ASSERT(str < end);
        *str = '\0';
        return str - buf;
}

int guest_snprintf(char *buf, int n, const char *fmt, ...)
{
        va_list va;
        int len;

        va_start(va, fmt);
        len = guest_vsnprintf(buf, n, fmt, va);
        va_end(va);

        return len;
}