// SPDX-License-Identifier: GPL-2.0
/*
 * Convert integer string representation to an integer.
 * If an integer doesn't fit into specified type, -E is returned.
 *
 * Integer starts with optional sign.
 * kstrtou*() functions do not accept sign "-".
 *
 * Radix 0 means autodetection: leading "0x" implies radix 16,
 * leading "0" implies radix 8, otherwise radix is 10.
 * Autodetection hints work after optional sign, but not before.
 *
 * If -E is returned, result is not touched.
 */
#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/export.h>
#include <linux/kstrtox.h>
#include <linux/math64.h>
#include <linux/types.h>
#include <linux/uaccess.h>

#include "kstrtox.h"

noinline
const char *_parse_integer_fixup_radix(const char *s, unsigned int *base)
{
        if (*base == 0) {
                if (s[0] == '0') {
                        if (_tolower(s[1]) == 'x' && isxdigit(s[2]))
                                *base = 16;
                        else
                                *base = 8;
                } else
                        *base = 10;
        }
        if (*base == 16 && s[0] == '0' && _tolower(s[1]) == 'x')
                s += 2;
        return s;
}

/*
 * Convert non-negative integer string representation in explicitly given radix
 * to an integer. A maximum of max_chars characters will be converted.
 *
 * Return number of characters consumed maybe or-ed with overflow bit.
 * If overflow occurs, result integer (incorrect) is still returned.
 *
 * Don't you dare use this function.
 */
noinline
unsigned int _parse_integer_limit(const char *s, unsigned int base, unsigned long long *p,
                                  size_t max_chars)
{
        unsigned long long res;
        unsigned int rv;

        res = 0;
        rv = 0;
        while (max_chars--) {
                unsigned int c = *s;
                unsigned int lc = _tolower(c);
                unsigned int val;

                if ('0' <= c && c <= '9')
                        val = c - '0';
                else if ('a' <= lc && lc <= 'f')
                        val = lc - 'a' + 10;
                else
                        break;

                if (val >= base)
                        break;
                /*
                 * Check for overflow only if we are within range of
                 * it in the max base we support (16)
                 */
                if (unlikely(res & (~0ull << 60))) {
                        if (res > div_u64(ULLONG_MAX - val, base))
                                rv |= KSTRTOX_OVERFLOW;
                }
                res = res * base + val;
                rv++;
                s++;
        }
        *p = res;
        return rv;
}

noinline
unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long *p)
{
        return _parse_integer_limit(s, base, p, INT_MAX);
}

static int _kstrtoull(const char *s, unsigned int base, unsigned long long *res)
{
        unsigned long long _res;
        unsigned int rv;

        s = _parse_integer_fixup_radix(s, &base);
        rv = _parse_integer(s, base, &_res);
        if (rv & KSTRTOX_OVERFLOW)
                return -ERANGE;
        if (rv == 0)
                return -EINVAL;
        s += rv;
        if (*s == '\n')
                s++;
        if (*s)
                return -EINVAL;
        *res = _res;
        return 0;
}

/**
 * kstrtoull - convert a string to an unsigned long long
 * @s: The start of the string. The string must be null-terminated, and may also
 *  include a single newline before its terminating null. The first character
 *  may also be a plus sign, but not a minus sign.
 * @base: The number base to use. The maximum supported base is 16. If base is
 *  given as 0, then the base of the string is automatically detected with the
 *  conventional semantics - If it begins with 0x the number will be parsed as a
 *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 * @res: Where to write the result of the conversion on success.
 *
 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 * Preferred over simple_strtoull(). Return code must be checked.
 */
noinline
int kstrtoull(const char *s, unsigned int base, unsigned long long *res)
{
        if (s[0] == '+')
                s++;
        return _kstrtoull(s, base, res);
}
EXPORT_SYMBOL(kstrtoull);

/**
 * kstrtoll - convert a string to a long long
 * @s: The start of the string. The string must be null-terminated, and may also
 *  include a single newline before its terminating null. The first character
 *  may also be a plus sign or a minus sign.
 * @base: The number base to use. The maximum supported base is 16. If base is
 *  given as 0, then the base of the string is automatically detected with the
 *  conventional semantics - If it begins with 0x the number will be parsed as a
 *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 * @res: Where to write the result of the conversion on success.
 *
 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 * Preferred over simple_strtoll(). Return code must be checked.
 */
noinline
int kstrtoll(const char *s, unsigned int base, long long *res)
{
        unsigned long long tmp;
        int rv;

        if (s[0] == '-') {
                rv = _kstrtoull(s + 1, base, &tmp);
                if (rv < 0)
                        return rv;
                if ((long long)-tmp > 0)
                        return -ERANGE;
                *res = -tmp;
        } else {
                rv = kstrtoull(s, base, &tmp);
                if (rv < 0)
                        return rv;
                if ((long long)tmp < 0)
                        return -ERANGE;
                *res = tmp;
        }
        return 0;
}
EXPORT_SYMBOL(kstrtoll);

/* Internal, do not use. */
int _kstrtoul(const char *s, unsigned int base, unsigned long *res)
{
        unsigned long long tmp;
        int rv;

        rv = kstrtoull(s, base, &tmp);
        if (rv < 0)
                return rv;
        if (tmp != (unsigned long)tmp)
                return -ERANGE;
        *res = tmp;
        return 0;
}
EXPORT_SYMBOL(_kstrtoul);

/* Internal, do not use. */
int _kstrtol(const char *s, unsigned int base, long *res)
{
        long long tmp;
        int rv;

        rv = kstrtoll(s, base, &tmp);
        if (rv < 0)
                return rv;
        if (tmp != (long)tmp)
                return -ERANGE;
        *res = tmp;
        return 0;
}
EXPORT_SYMBOL(_kstrtol);

/**
 * kstrtouint - convert a string to an unsigned int
 * @s: The start of the string. The string must be null-terminated, and may also
 *  include a single newline before its terminating null. The first character
 *  may also be a plus sign, but not a minus sign.
 * @base: The number base to use. The maximum supported base is 16. If base is
 *  given as 0, then the base of the string is automatically detected with the
 *  conventional semantics - If it begins with 0x the number will be parsed as a
 *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 * @res: Where to write the result of the conversion on success.
 *
 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 * Preferred over simple_strtoul(). Return code must be checked.
 */
noinline
int kstrtouint(const char *s, unsigned int base, unsigned int *res)
{
        unsigned long long tmp;
        int rv;

        rv = kstrtoull(s, base, &tmp);
        if (rv < 0)
                return rv;
        if (tmp != (unsigned int)tmp)
                return -ERANGE;
        *res = tmp;
        return 0;
}
EXPORT_SYMBOL(kstrtouint);

/**
 * kstrtoint - convert a string to an int
 * @s: The start of the string. The string must be null-terminated, and may also
 *  include a single newline before its terminating null. The first character
 *  may also be a plus sign or a minus sign.
 * @base: The number base to use. The maximum supported base is 16. If base is
 *  given as 0, then the base of the string is automatically detected with the
 *  conventional semantics - If it begins with 0x the number will be parsed as a
 *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 * @res: Where to write the result of the conversion on success.
 *
 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 * Preferred over simple_strtol(). Return code must be checked.
 */
noinline
int kstrtoint(const char *s, unsigned int base, int *res)
{
        long long tmp;
        int rv;

        rv = kstrtoll(s, base, &tmp);
        if (rv < 0)
                return rv;
        if (tmp != (int)tmp)
                return -ERANGE;
        *res = tmp;
        return 0;
}
EXPORT_SYMBOL(kstrtoint);

noinline
int kstrtou16(const char *s, unsigned int base, u16 *res)
{
        unsigned long long tmp;
        int rv;

        rv = kstrtoull(s, base, &tmp);
        if (rv < 0)
                return rv;
        if (tmp != (u16)tmp)
                return -ERANGE;
        *res = tmp;
        return 0;
}
EXPORT_SYMBOL(kstrtou16);

noinline
int kstrtos16(const char *s, unsigned int base, s16 *res)
{
        long long tmp;
        int rv;

        rv = kstrtoll(s, base, &tmp);
        if (rv < 0)
                return rv;
        if (tmp != (s16)tmp)
                return -ERANGE;
        *res = tmp;
        return 0;
}
EXPORT_SYMBOL(kstrtos16);

noinline
int kstrtou8(const char *s, unsigned int base, u8 *res)
{
        unsigned long long tmp;
        int rv;

        rv = kstrtoull(s, base, &tmp);
        if (rv < 0)
                return rv;
        if (tmp != (u8)tmp)
                return -ERANGE;
        *res = tmp;
        return 0;
}
EXPORT_SYMBOL(kstrtou8);

noinline
int kstrtos8(const char *s, unsigned int base, s8 *res)
{
        long long tmp;
        int rv;

        rv = kstrtoll(s, base, &tmp);
        if (rv < 0)
                return rv;
        if (tmp != (s8)tmp)
                return -ERANGE;
        *res = tmp;
        return 0;
}
EXPORT_SYMBOL(kstrtos8);

/**
 * kstrtobool - convert common user inputs into boolean values
 * @s: input string
 * @res: result
 *
 * This routine returns 0 iff the first character is one of 'EeYyTt1DdNnFf0',
 * or [oO][NnFf] for "on" and "off". Otherwise it will return -EINVAL.  Value
 * pointed to by res is updated upon finding a match.
 */
noinline
int kstrtobool(const char *s, bool *res)
{
        if (!s)
                return -EINVAL;

        switch (s[0]) {
        case 'e':
        case 'E':
        case 'y':
        case 'Y':
        case 't':
        case 'T':
        case '1':
                *res = true;
                return 0;
        case 'd':
        case 'D':
        case 'n':
        case 'N':
        case 'f':
        case 'F':
        case '0':
                *res = false;
                return 0;
        case 'o':
        case 'O':
                switch (s[1]) {
                case 'n':
                case 'N':
                        *res = true;
                        return 0;
                case 'f':
                case 'F':
                        *res = false;
                        return 0;
                default:
                        break;
                }
                break;
        default:
                break;
        }

        return -EINVAL;
}
EXPORT_SYMBOL(kstrtobool);

/*
 * Since "base" would be a nonsense argument, this open-codes the
 * _from_user helper instead of using the helper macro below.
 */
int kstrtobool_from_user(const char __user *s, size_t count, bool *res)
{
        /* Longest string needed to differentiate, newline, terminator */
        char buf[4];

        count = min(count, sizeof(buf) - 1);
        if (copy_from_user(buf, s, count))
                return -EFAULT;
        buf[count] = '\0';
        return kstrtobool(buf, res);
}
EXPORT_SYMBOL(kstrtobool_from_user);

#define kstrto_from_user(f, g, type)                                    \
int f(const char __user *s, size_t count, unsigned int base, type *res) \
{                                                                       \
        /* sign, base 2 representation, newline, terminator */          \
        char buf[1 + sizeof(type) * 8 + 1 + 1];                         \
                                                                        \
        count = min(count, sizeof(buf) - 1);                            \
        if (copy_from_user(buf, s, count))                              \
                return -EFAULT;                                         \
        buf[count] = '\0';                                              \
        return g(buf, base, res);                                       \
}                                                                       \
EXPORT_SYMBOL(f)

kstrto_from_user(kstrtoull_from_user,   kstrtoull,      unsigned long long);
kstrto_from_user(kstrtoll_from_user,    kstrtoll,       long long);
kstrto_from_user(kstrtoul_from_user,    kstrtoul,       unsigned long);
kstrto_from_user(kstrtol_from_user,     kstrtol,        long);
kstrto_from_user(kstrtouint_from_user,  kstrtouint,     unsigned int);
kstrto_from_user(kstrtoint_from_user,   kstrtoint,      int);
kstrto_from_user(kstrtou16_from_user,   kstrtou16,      u16);
kstrto_from_user(kstrtos16_from_user,   kstrtos16,      s16);
kstrto_from_user(kstrtou8_from_user,    kstrtou8,       u8);
kstrto_from_user(kstrtos8_from_user,    kstrtos8,       s8);