[PATCH v3 3/4] rust: str: add radix prefixed integer parsing functions

Andreas Hindborg
2024-12-13T11:33:48Z

Add the trait `ParseInt` for parsing string representations of integers
where the string representations are optionally prefixed by a radix
specifier. Implement the trait for the primitive integer types.

Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
---
rust/kernel/str.rs | 116 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 116 insertions(+)

diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 9c446ff1ad7adba7ca09a5ae9df00fd369a32899..4da711f264397c7a1fce34edb69a71253d03911e 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -914,3 +914,119 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
macro_rules! fmt {
($($f:tt)*) => ( core::format_args!($($f)*) )
}
+
+pub mod parse_int {
+ //! Integer parsing functions for parsing signed and unsigned integers
+ //! potentially prefixed with `0x`, `0o`, or `0b`.
+
+ use crate::alloc::flags;
+ use crate::prelude::*;
+ use crate::str::BStr;
+
+ /// Trait that allows parsing a `&BStr` to an integer with a radix.
+ // This is required because the `from_str_radix` function on the primitive
+ // integer types is not part of any trait.
+ pub trait FromStrRadix: Sized {
+ /// Parse `src` to `Self` using radix `radix`.
+ fn from_str_radix(src: &BStr, radix: u32) -> Result<Self, crate::error::Error>;
+ }
+
+ /// 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) {
+ if let Some(n) = src.strip_prefix(b_str!("0x")) {
+ (16, n)
+ } else if let Some(n) = src.strip_prefix(b_str!("0X")) {
+ (16, n)
+ } else if let Some(n) = src.strip_prefix(b_str!("0o")) {
+ (8, n)
+ } else if let Some(n) = src.strip_prefix(b_str!("0O")) {
+ (8, n)
+ } else if let Some(n) = src.strip_prefix(b_str!("0b")) {
+ (2, n)
+ } else if let Some(n) = src.strip_prefix(b_str!("0B")) {
+ (2, n)
+ } else if let Some(n) = src.strip_prefix(b_str!("0")) {
+ (8, n)
+ } else {
+ (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://www.kernel.org/doc/html/latest/core-api/kernel-api.html#c.kstrtol
+ /// [`kstrtoul()`]: https://www.kernel.org/doc/html/latest/core-api/kernel-api.html#c.kstrtoul
+ ///
+ /// # Example
+ /// ```
+ /// use kernel::str::parse_int::ParseInt;
+ /// use kernel::b_str;
+ ///
+ /// 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(127), i8::from_str(b_str!("127")));
+ /// assert!(i8::from_str(b_str!("128")).is_err());
+ /// assert_eq!(Ok(-128), i8::from_str(b_str!("-128")));
+ /// assert!(i8::from_str(b_str!("-129")).is_err());
+ /// assert_eq!(Ok(255), u8::from_str(b_str!("255")));
+ /// assert!(u8::from_str(b_str!("256")).is_err());
+ /// ```
+ pub trait ParseInt: FromStrRadix {
+ /// Parse a string according to the description in [`Self`].
+ fn from_str(src: &BStr) -> Result<Self> {
+ match src.iter().next() {
+ None => Err(EINVAL),
+ Some(sign @ b'-') | Some(sign @ b'+') => {
+ let (radix, digits) = strip_radix(BStr::from_bytes(&src[1..]));
+ let mut n_digits: KVec<u8> =
+ KVec::with_capacity(digits.len() + 1, flags::GFP_KERNEL)?;
+ n_digits.push(*sign, flags::GFP_KERNEL)?;
+ n_digits.extend_from_slice(digits, flags::GFP_KERNEL)?;
+ Self::from_str_radix(BStr::from_bytes(&n_digits), radix).map_err(|_| EINVAL)
+ }
+ Some(_) => {
+ let (radix, digits) = strip_radix(src);
+ Self::from_str_radix(digits, radix).map_err(|_| EINVAL)
+ }
+ }
+ }
+ }
+
+ macro_rules! impl_parse_int {
+ ($ty:ty) => {
+ impl FromStrRadix for $ty {
+ fn from_str_radix(src: &BStr, radix: u32) -> Result<Self, crate::error::Error> {
+ <$ty>::from_str_radix(core::str::from_utf8(src).map_err(|_| EINVAL)?, radix)
+ .map_err(|_| EINVAL)
+ }
+ }
+
+ impl ParseInt for $ty {}
+ };
+ }
+
+ impl_parse_int!(i8);
+ impl_parse_int!(u8);
+ impl_parse_int!(i16);
+ impl_parse_int!(u16);
+ impl_parse_int!(i32);
+ impl_parse_int!(u32);
+ impl_parse_int!(i64);
+ impl_parse_int!(u64);
+ impl_parse_int!(isize);
+ impl_parse_int!(usize);
+}

--
2.47.0