Vendor things

third-party/vendor/rustix/src/ioctl/patterns.rs

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+//! Implements typical patterns for `ioctl` usage.
+
+use super::{Ioctl, IoctlOutput, Opcode, RawOpcode};
+
+use crate::backend::c;
+use crate::io::Result;
+
+use core::marker::PhantomData;
+use core::ptr::addr_of_mut;
+use core::{fmt, mem};
+
+/// Implements an `ioctl` with no real arguments.
+pub struct NoArg<Opcode> {
+    /// The opcode.
+    _opcode: PhantomData<Opcode>,
+}
+
+impl<Opcode: CompileTimeOpcode> fmt::Debug for NoArg<Opcode> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_tuple("NoArg").field(&Opcode::OPCODE).finish()
+    }
+}
+
+impl<Opcode: CompileTimeOpcode> NoArg<Opcode> {
+    /// Create a new no-argument `ioctl` object.
+    ///
+    /// # Safety
+    ///
+    /// - `Opcode` must provide a valid opcode.
+    #[inline]
+    pub unsafe fn new() -> Self {
+        Self {
+            _opcode: PhantomData,
+        }
+    }
+}
+
+unsafe impl<Opcode: CompileTimeOpcode> Ioctl for NoArg<Opcode> {
+    type Output = ();
+
+    const IS_MUTATING: bool = false;
+    const OPCODE: self::Opcode = Opcode::OPCODE;
+
+    fn as_ptr(&mut self) -> *mut c::c_void {
+        core::ptr::null_mut()
+    }
+
+    unsafe fn output_from_ptr(_: IoctlOutput, _: *mut c::c_void) -> Result<Self::Output> {
+        Ok(())
+    }
+}
+
+/// Implements the traditional “getter” pattern for `ioctl`s.
+///
+/// Some `ioctl`s just read data into the userspace. As this is a popular
+/// pattern this structure implements it.
+pub struct Getter<Opcode, Output> {
+    /// The output data.
+    output: mem::MaybeUninit<Output>,
+
+    /// The opcode.
+    _opcode: PhantomData<Opcode>,
+}
+
+impl<Opcode: CompileTimeOpcode, Output> fmt::Debug for Getter<Opcode, Output> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_tuple("Getter").field(&Opcode::OPCODE).finish()
+    }
+}
+
+impl<Opcode: CompileTimeOpcode, Output> Getter<Opcode, Output> {
+    /// Create a new getter-style `ioctl` object.
+    ///
+    /// # Safety
+    ///
+    /// - `Opcode` must provide a valid opcode.
+    /// - For this opcode, `Output` must be the type that the kernel expects to
+    ///   write into.
+    #[inline]
+    pub unsafe fn new() -> Self {
+        Self {
+            output: mem::MaybeUninit::uninit(),
+            _opcode: PhantomData,
+        }
+    }
+}
+
+unsafe impl<Opcode: CompileTimeOpcode, Output> Ioctl for Getter<Opcode, Output> {
+    type Output = Output;
+
+    const IS_MUTATING: bool = true;
+    const OPCODE: self::Opcode = Opcode::OPCODE;
+
+    fn as_ptr(&mut self) -> *mut c::c_void {
+        self.output.as_mut_ptr().cast()
+    }
+
+    unsafe fn output_from_ptr(_: IoctlOutput, ptr: *mut c::c_void) -> Result<Self::Output> {
+        Ok(ptr.cast::<Output>().read())
+    }
+}
+
+/// Implements the pattern for `ioctl`s where a pointer argument is given to
+/// the `ioctl`.
+///
+/// The opcode must be read-only.
+pub struct Setter<Opcode, Input> {
+    /// The input data.
+    input: Input,
+
+    /// The opcode.
+    _opcode: PhantomData<Opcode>,
+}
+
+impl<Opcode: CompileTimeOpcode, Input: fmt::Debug> fmt::Debug for Setter<Opcode, Input> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_tuple("Setter")
+            .field(&Opcode::OPCODE)
+            .field(&self.input)
+            .finish()
+    }
+}
+
+impl<Opcode: CompileTimeOpcode, Input> Setter<Opcode, Input> {
+    /// Create a new pointer setter-style `ioctl` object.
+    ///
+    /// # Safety
+    ///
+    /// - `Opcode` must provide a valid opcode.
+    /// - For this opcode, `Input` must be the type that the kernel expects to
+    ///   get.
+    #[inline]
+    pub unsafe fn new(input: Input) -> Self {
+        Self {
+            input,
+            _opcode: PhantomData,
+        }
+    }
+}
+
+unsafe impl<Opcode: CompileTimeOpcode, Input> Ioctl for Setter<Opcode, Input> {
+    type Output = ();
+
+    const IS_MUTATING: bool = false;
+    const OPCODE: self::Opcode = Opcode::OPCODE;
+
+    fn as_ptr(&mut self) -> *mut c::c_void {
+        addr_of_mut!(self.input).cast::<c::c_void>()
+    }
+
+    unsafe fn output_from_ptr(_: IoctlOutput, _: *mut c::c_void) -> Result<Self::Output> {
+        Ok(())
+    }
+}
+
+/// Implements an “updater” pattern for `ioctl`s.
+///
+/// The ioctl takes a reference to a struct that it reads its input from,
+/// then writes output to the same struct.
+pub struct Updater<'a, Opcode, Value> {
+    /// Reference to input/output data.
+    value: &'a mut Value,
+
+    /// The opcode.
+    _opcode: PhantomData<Opcode>,
+}
+
+impl<'a, Opcode: CompileTimeOpcode, Value> Updater<'a, Opcode, Value> {
+    /// Create a new pointer updater-style `ioctl` object.
+    ///
+    /// # Safety
+    ///
+    /// - `Opcode` must provide a valid opcode.
+    /// - For this opcode, `Value` must be the type that the kernel expects to
+    ///   get.
+    #[inline]
+    pub unsafe fn new(value: &'a mut Value) -> Self {
+        Self {
+            value,
+            _opcode: PhantomData,
+        }
+    }
+}
+
+unsafe impl<'a, Opcode: CompileTimeOpcode, T> Ioctl for Updater<'a, Opcode, T> {
+    type Output = ();
+
+    const IS_MUTATING: bool = true;
+    const OPCODE: self::Opcode = Opcode::OPCODE;
+
+    fn as_ptr(&mut self) -> *mut c::c_void {
+        (self.value as *mut T).cast()
+    }
+
+    unsafe fn output_from_ptr(_output: IoctlOutput, _ptr: *mut c::c_void) -> Result<()> {
+        Ok(())
+    }
+}
+
+/// Trait for something that provides an `ioctl` opcode at compile time.
+pub trait CompileTimeOpcode {
+    /// The opcode.
+    const OPCODE: Opcode;
+}
+
+/// Provides a bad opcode at compile time.
+pub struct BadOpcode<const OPCODE: RawOpcode>;
+
+impl<const OPCODE: RawOpcode> CompileTimeOpcode for BadOpcode<OPCODE> {
+    const OPCODE: Opcode = Opcode::old(OPCODE);
+}
+
+/// Provides a read code at compile time.
+///
+/// This corresponds to the C macro `_IOR(GROUP, NUM, Data)`.
+#[cfg(any(linux_kernel, bsd))]
+pub struct ReadOpcode<const GROUP: u8, const NUM: u8, Data>(Data);
+
+#[cfg(any(linux_kernel, bsd))]
+impl<const GROUP: u8, const NUM: u8, Data> CompileTimeOpcode for ReadOpcode<GROUP, NUM, Data> {
+    const OPCODE: Opcode = Opcode::read::<Data>(GROUP, NUM);
+}
+
+/// Provides a write code at compile time.
+///
+/// This corresponds to the C macro `_IOW(GROUP, NUM, Data)`.
+#[cfg(any(linux_kernel, bsd))]
+pub struct WriteOpcode<const GROUP: u8, const NUM: u8, Data>(Data);
+
+#[cfg(any(linux_kernel, bsd))]
+impl<const GROUP: u8, const NUM: u8, Data> CompileTimeOpcode for WriteOpcode<GROUP, NUM, Data> {
+    const OPCODE: Opcode = Opcode::write::<Data>(GROUP, NUM);
+}
+
+/// Provides a read/write code at compile time.
+///
+/// This corresponds to the C macro `_IOWR(GROUP, NUM, Data)`.
+#[cfg(any(linux_kernel, bsd))]
+pub struct ReadWriteOpcode<const GROUP: u8, const NUM: u8, Data>(Data);
+
+#[cfg(any(linux_kernel, bsd))]
+impl<const GROUP: u8, const NUM: u8, Data> CompileTimeOpcode for ReadWriteOpcode<GROUP, NUM, Data> {
+    const OPCODE: Opcode = Opcode::read_write::<Data>(GROUP, NUM);
+}
+
+/// Provides a `None` code at compile time.
+///
+/// This corresponds to the C macro `_IO(GROUP, NUM)` when `Data` is zero
+/// sized.
+#[cfg(any(linux_kernel, bsd))]
+pub struct NoneOpcode<const GROUP: u8, const NUM: u8, Data>(Data);
+
+#[cfg(any(linux_kernel, bsd))]
+impl<const GROUP: u8, const NUM: u8, Data> CompileTimeOpcode for NoneOpcode<GROUP, NUM, Data> {
+    const OPCODE: Opcode = Opcode::none::<Data>(GROUP, NUM);
+}