// SPDX-License-Identifier: GPL-2.0 //! Integer parsing functions.//!//! Integer parsing functions for parsing signed and unsigned integers//! potentially prefixed with `0x`, `0o`, or `0b`. use crate::prelude::*;use crate::str::BStr;use core::ops::Deref; // Make `FromStrRadix` a public type with a private name. This seals// `ParseInt`, that is, prevents downstream users from implementing the// trait.mod private {    use crate::prelude::*;    use crate::str::BStr;     /// Trait that allows parsing a [`&BStr`] to an integer with a radix.    pub trait FromStrRadix: Sized {        /// Parse `src` to [`Self`] using radix `radix`.        fn from_str_radix(src: &BStr, radix: u32) -> Result<Self>;         /// Tries to convert `value` into [`Self`] and negates the resulting value.        fn from_u64_negated(value: u64) -> Result<Self>;    }} /// Extract the radix from an integer literal optionally prefixed with/// one of `0x`, `0X`, `0o`, `0O`, `0b`, `0B`, `0`.fn strip_radix(src: &BStr) -> (u32, &BStr) {    match src.deref() {        [b'0', b'x' | b'X', rest @ ..] => (16, rest.as_ref()),        [b'0', b'o' | b'O', rest @ ..] => (8, rest.as_ref()),        [b'0', b'b' | b'B', rest @ ..] => (2, rest.as_ref()),        // NOTE: We are including the leading zero to be able to parse        // literal `0` here. If we removed it as a radix prefix, we would        // not be able to parse `0`.        [b'0', ..] => (8, src),        _ => (10, src),    }} /// Trait for parsing string representations of integers.////// Strings beginning with `0x`, `0o`, or `0b` are parsed as hex, octal, or/// binary respectively. Strings beginning with `0` otherwise are parsed as/// octal. Anything else is parsed as decimal. A leading `+` or `-` is also/// permitted. Any string parsed by [`kstrtol()`] or [`kstrtoul()`] will be/// successfully parsed.////// [`kstrtol()`]: https://docs.kernel.org/core-api/kernel-api.html#c.kstrtol/// [`kstrtoul()`]: https://docs.kernel.org/core-api/kernel-api.html#c.kstrtoul////// # Examples////// ```/// # use kernel::str::parse_int::ParseInt;/// # use kernel::b_str;////// assert_eq!(Ok(0u8), u8::from_str(b_str!("0")));////// assert_eq!(Ok(0xa2u8), u8::from_str(b_str!("0xa2")));/// assert_eq!(Ok(-0xa2i32), i32::from_str(b_str!("-0xa2")));////// assert_eq!(Ok(-0o57i8), i8::from_str(b_str!("-0o57")));/// assert_eq!(Ok(0o57i8), i8::from_str(b_str!("057")));////// assert_eq!(Ok(0b1001i16), i16::from_str(b_str!("0b1001")));/// assert_eq!(Ok(-0b1001i16), i16::from_str(b_str!("-0b1001")));////// assert_eq!(Ok(127i8), i8::from_str(b_str!("127")));/// assert!(i8::from_str(b_str!("128")).is_err());/// assert_eq!(Ok(-128i8), i8::from_str(b_str!("-128")));/// assert!(i8::from_str(b_str!("-129")).is_err());/// assert_eq!(Ok(255u8), u8::from_str(b_str!("255")));/// assert!(u8::from_str(b_str!("256")).is_err());/// ```pub trait ParseInt: private::FromStrRadix + TryFrom<u64> {    /// Parse a string according to the description in [`Self`].    fn from_str(src: &BStr) -> Result<Self> {        match src.deref() {            [b'-', rest @ ..] => {                let (radix, digits) = strip_radix(rest.as_ref());                // 2's complement values range from -2^(b-1) to 2^(b-1)-1.                // So if we want to parse negative numbers as positive and                // later multiply by -1, we have to parse into a larger                // integer. We choose `u64` as sufficiently large.                //                // NOTE: 128 bit integers are not available on all                // platforms, hence the choice of 64 bits.                let val =                    u64::from_str_radix(core::str::from_utf8(digits).map_err(|_| EINVAL)?, radix)                        .map_err(|_| EINVAL)?;                Self::from_u64_negated(val)            }            _ => {                let (radix, digits) = strip_radix(src);                Self::from_str_radix(digits, radix).map_err(|_| EINVAL)            }        }    }} macro_rules! impl_parse_int {    ($($ty:ty),*) => {        $(            impl private::FromStrRadix for $ty {                fn from_str_radix(src: &BStr, radix: u32) -> Result<Self> {                    <$ty>::from_str_radix(core::str::from_utf8(src).map_err(|_| EINVAL)?, radix)                        .map_err(|_| EINVAL)                }                 fn from_u64_negated(value: u64) -> Result<Self> {                    const ABS_MIN: u64 = {                        #[allow(unused_comparisons)]                        if <$ty>::MIN < 0 {                            1u64 << (<$ty>::BITS - 1)                        } else {                            0                        }                    };                     if value > ABS_MIN {                        return Err(EINVAL);                    }                     if value == ABS_MIN {                        return Ok(<$ty>::MIN);                    }                     // SAFETY: The above checks guarantee that `value` fits into `Self`:                    // - if `Self` is unsigned, then `ABS_MIN == 0` and thus we have returned above                    //   (either `EINVAL` or `MIN`).                    // - if `Self` is signed, then we have that `0 <= value < ABS_MIN`. And since                    //   `ABS_MIN - 1` fits into `Self` by construction, `value` also does.                    let value: Self = unsafe { value.try_into().unwrap_unchecked() };                     Ok((!value).wrapping_add(1))                }            }             impl ParseInt for $ty {}        )*    };} impl_parse_int![i8, u8, i16, u16, i32, u32, i64, u64, isize, usize];