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// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2025 Google LLC.
//! Traits for rendering or updating values exported to DebugFS.
use crate::prelude::*;
use crate::sync::Mutex;
use crate::uaccess::UserSliceReader;
use core::fmt::{self, Debug, Formatter};
use core::str::FromStr;
use core::sync::atomic::{
AtomicI16, AtomicI32, AtomicI64, AtomicI8, AtomicIsize, AtomicU16, AtomicU32, AtomicU64,
AtomicU8, AtomicUsize, Ordering,
};
/// A trait for types that can be written into a string.
///
/// This works very similarly to `Debug`, and is automatically implemented if `Debug` is
/// implemented for a type. It is also implemented for any writable type inside a `Mutex`.
///
/// The derived implementation of `Debug` [may
/// change](https://doc.rust-lang.org/std/fmt/trait.Debug.html#stability)
/// between Rust versions, so if stability is key for your use case, please implement `Writer`
/// explicitly instead.
pub trait Writer {
/// Formats the value using the given formatter.
fn write(&self, f: &mut Formatter<'_>) -> fmt::Result;
}
impl<T: Writer> Writer for Mutex<T> {
fn write(&self, f: &mut Formatter<'_>) -> fmt::Result {
self.lock().write(f)
}
}
impl<T: Debug> Writer for T {
fn write(&self, f: &mut Formatter<'_>) -> fmt::Result {
writeln!(f, "{self:?}")
}
}
/// A trait for types that can be updated from a user slice.
///
/// This works similarly to `FromStr`, but operates on a `UserSliceReader` rather than a &str.
///
/// It is automatically implemented for all atomic integers, or any type that implements `FromStr`
/// wrapped in a `Mutex`.
pub trait Reader {
/// Updates the value from the given user slice.
fn read_from_slice(&self, reader: &mut UserSliceReader) -> Result;
}
impl<T: FromStr> Reader for Mutex<T> {
fn read_from_slice(&self, reader: &mut UserSliceReader) -> Result {
let mut buf = [0u8; 128];
if reader.len() > buf.len() {
return Err(EINVAL);
}
let n = reader.len();
reader.read_slice(&mut buf[..n])?;
let s = core::str::from_utf8(&buf[..n]).map_err(|_| EINVAL)?;
let val = s.trim().parse::<T>().map_err(|_| EINVAL)?;
*self.lock() = val;
Ok(())
}
}
macro_rules! impl_reader_for_atomic {
($(($atomic_type:ty, $int_type:ty)),*) => {
$(
impl Reader for $atomic_type {
fn read_from_slice(&self, reader: &mut UserSliceReader) -> Result {
let mut buf = [0u8; 21]; // Enough for a 64-bit number.
if reader.len() > buf.len() {
return Err(EINVAL);
}
let n = reader.len();
reader.read_slice(&mut buf[..n])?;
let s = core::str::from_utf8(&buf[..n]).map_err(|_| EINVAL)?;
let val = s.trim().parse::<$int_type>().map_err(|_| EINVAL)?;
self.store(val, Ordering::Relaxed);
Ok(())
}
}
)*
};
}
impl_reader_for_atomic!(
(AtomicI16, i16),
(AtomicI32, i32),
(AtomicI64, i64),
(AtomicI8, i8),
(AtomicIsize, isize),
(AtomicU16, u16),
(AtomicU32, u32),
(AtomicU64, u64),
(AtomicU8, u8),
(AtomicUsize, usize)
);
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