rustix/ioctl/
patterns.rs

1//! Implements typical patterns for `ioctl` usage.
2
3use super::{Ioctl, IoctlOutput, Opcode, RawOpcode};
4
5use crate::backend::c;
6use crate::io::Result;
7
8use core::marker::PhantomData;
9use core::ptr::addr_of_mut;
10use core::{fmt, mem};
11
12/// Implements an `ioctl` with no real arguments.
13pub struct NoArg<Opcode> {
14    /// The opcode.
15    _opcode: PhantomData<Opcode>,
16}
17
18impl<Opcode: CompileTimeOpcode> fmt::Debug for NoArg<Opcode> {
19    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
20        f.debug_tuple("NoArg").field(&Opcode::OPCODE).finish()
21    }
22}
23
24impl<Opcode: CompileTimeOpcode> NoArg<Opcode> {
25    /// Create a new no-argument `ioctl` object.
26    ///
27    /// # Safety
28    ///
29    /// - `Opcode` must provide a valid opcode.
30    #[inline]
31    pub unsafe fn new() -> Self {
32        Self {
33            _opcode: PhantomData,
34        }
35    }
36}
37
38unsafe impl<Opcode: CompileTimeOpcode> Ioctl for NoArg<Opcode> {
39    type Output = ();
40
41    const IS_MUTATING: bool = false;
42    const OPCODE: self::Opcode = Opcode::OPCODE;
43
44    fn as_ptr(&mut self) -> *mut c::c_void {
45        core::ptr::null_mut()
46    }
47
48    unsafe fn output_from_ptr(_: IoctlOutput, _: *mut c::c_void) -> Result<Self::Output> {
49        Ok(())
50    }
51}
52
53/// Implements the traditional “getter” pattern for `ioctl`s.
54///
55/// Some `ioctl`s just read data into the userspace. As this is a popular
56/// pattern this structure implements it.
57pub struct Getter<Opcode, Output> {
58    /// The output data.
59    output: mem::MaybeUninit<Output>,
60
61    /// The opcode.
62    _opcode: PhantomData<Opcode>,
63}
64
65impl<Opcode: CompileTimeOpcode, Output> fmt::Debug for Getter<Opcode, Output> {
66    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
67        f.debug_tuple("Getter").field(&Opcode::OPCODE).finish()
68    }
69}
70
71impl<Opcode: CompileTimeOpcode, Output> Getter<Opcode, Output> {
72    /// Create a new getter-style `ioctl` object.
73    ///
74    /// # Safety
75    ///
76    /// - `Opcode` must provide a valid opcode.
77    /// - For this opcode, `Output` must be the type that the kernel expects to
78    ///   write into.
79    #[inline]
80    pub unsafe fn new() -> Self {
81        Self {
82            output: mem::MaybeUninit::uninit(),
83            _opcode: PhantomData,
84        }
85    }
86}
87
88unsafe impl<Opcode: CompileTimeOpcode, Output> Ioctl for Getter<Opcode, Output> {
89    type Output = Output;
90
91    const IS_MUTATING: bool = true;
92    const OPCODE: self::Opcode = Opcode::OPCODE;
93
94    fn as_ptr(&mut self) -> *mut c::c_void {
95        self.output.as_mut_ptr().cast()
96    }
97
98    unsafe fn output_from_ptr(_: IoctlOutput, ptr: *mut c::c_void) -> Result<Self::Output> {
99        Ok(ptr.cast::<Output>().read())
100    }
101}
102
103/// Implements the pattern for `ioctl`s where a pointer argument is given to
104/// the `ioctl`.
105///
106/// The opcode must be read-only.
107pub struct Setter<Opcode, Input> {
108    /// The input data.
109    input: Input,
110
111    /// The opcode.
112    _opcode: PhantomData<Opcode>,
113}
114
115impl<Opcode: CompileTimeOpcode, Input: fmt::Debug> fmt::Debug for Setter<Opcode, Input> {
116    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
117        f.debug_tuple("Setter")
118            .field(&Opcode::OPCODE)
119            .field(&self.input)
120            .finish()
121    }
122}
123
124impl<Opcode: CompileTimeOpcode, Input> Setter<Opcode, Input> {
125    /// Create a new pointer setter-style `ioctl` object.
126    ///
127    /// # Safety
128    ///
129    /// - `Opcode` must provide a valid opcode.
130    /// - For this opcode, `Input` must be the type that the kernel expects to
131    ///   get.
132    #[inline]
133    pub unsafe fn new(input: Input) -> Self {
134        Self {
135            input,
136            _opcode: PhantomData,
137        }
138    }
139}
140
141unsafe impl<Opcode: CompileTimeOpcode, Input> Ioctl for Setter<Opcode, Input> {
142    type Output = ();
143
144    const IS_MUTATING: bool = false;
145    const OPCODE: self::Opcode = Opcode::OPCODE;
146
147    fn as_ptr(&mut self) -> *mut c::c_void {
148        addr_of_mut!(self.input).cast::<c::c_void>()
149    }
150
151    unsafe fn output_from_ptr(_: IoctlOutput, _: *mut c::c_void) -> Result<Self::Output> {
152        Ok(())
153    }
154}
155
156/// Implements an “updater” pattern for `ioctl`s.
157///
158/// The ioctl takes a reference to a struct that it reads its input from,
159/// then writes output to the same struct.
160pub struct Updater<'a, Opcode, Value> {
161    /// Reference to input/output data.
162    value: &'a mut Value,
163
164    /// The opcode.
165    _opcode: PhantomData<Opcode>,
166}
167
168impl<'a, Opcode: CompileTimeOpcode, Value> Updater<'a, Opcode, Value> {
169    /// Create a new pointer updater-style `ioctl` object.
170    ///
171    /// # Safety
172    ///
173    /// - `Opcode` must provide a valid opcode.
174    /// - For this opcode, `Value` must be the type that the kernel expects to
175    ///   get.
176    #[inline]
177    pub unsafe fn new(value: &'a mut Value) -> Self {
178        Self {
179            value,
180            _opcode: PhantomData,
181        }
182    }
183}
184
185unsafe impl<'a, Opcode: CompileTimeOpcode, T> Ioctl for Updater<'a, Opcode, T> {
186    type Output = ();
187
188    const IS_MUTATING: bool = true;
189    const OPCODE: self::Opcode = Opcode::OPCODE;
190
191    fn as_ptr(&mut self) -> *mut c::c_void {
192        (self.value as *mut T).cast()
193    }
194
195    unsafe fn output_from_ptr(_output: IoctlOutput, _ptr: *mut c::c_void) -> Result<()> {
196        Ok(())
197    }
198}
199
200/// Trait for something that provides an `ioctl` opcode at compile time.
201pub trait CompileTimeOpcode {
202    /// The opcode.
203    const OPCODE: Opcode;
204}
205
206/// Provides a bad opcode at compile time.
207pub struct BadOpcode<const OPCODE: RawOpcode>;
208
209impl<const OPCODE: RawOpcode> CompileTimeOpcode for BadOpcode<OPCODE> {
210    const OPCODE: Opcode = Opcode::old(OPCODE);
211}
212
213/// Provides a read code at compile time.
214///
215/// This corresponds to the C macro `_IOR(GROUP, NUM, Data)`.
216#[cfg(any(linux_kernel, bsd))]
217pub struct ReadOpcode<const GROUP: u8, const NUM: u8, Data>(Data);
218
219#[cfg(any(linux_kernel, bsd))]
220impl<const GROUP: u8, const NUM: u8, Data> CompileTimeOpcode for ReadOpcode<GROUP, NUM, Data> {
221    const OPCODE: Opcode = Opcode::read::<Data>(GROUP, NUM);
222}
223
224/// Provides a write code at compile time.
225///
226/// This corresponds to the C macro `_IOW(GROUP, NUM, Data)`.
227#[cfg(any(linux_kernel, bsd))]
228pub struct WriteOpcode<const GROUP: u8, const NUM: u8, Data>(Data);
229
230#[cfg(any(linux_kernel, bsd))]
231impl<const GROUP: u8, const NUM: u8, Data> CompileTimeOpcode for WriteOpcode<GROUP, NUM, Data> {
232    const OPCODE: Opcode = Opcode::write::<Data>(GROUP, NUM);
233}
234
235/// Provides a read/write code at compile time.
236///
237/// This corresponds to the C macro `_IOWR(GROUP, NUM, Data)`.
238#[cfg(any(linux_kernel, bsd))]
239pub struct ReadWriteOpcode<const GROUP: u8, const NUM: u8, Data>(Data);
240
241#[cfg(any(linux_kernel, bsd))]
242impl<const GROUP: u8, const NUM: u8, Data> CompileTimeOpcode for ReadWriteOpcode<GROUP, NUM, Data> {
243    const OPCODE: Opcode = Opcode::read_write::<Data>(GROUP, NUM);
244}
245
246/// Provides a `None` code at compile time.
247///
248/// This corresponds to the C macro `_IO(GROUP, NUM)` when `Data` is zero
249/// sized.
250#[cfg(any(linux_kernel, bsd))]
251pub struct NoneOpcode<const GROUP: u8, const NUM: u8, Data>(Data);
252
253#[cfg(any(linux_kernel, bsd))]
254impl<const GROUP: u8, const NUM: u8, Data> CompileTimeOpcode for NoneOpcode<GROUP, NUM, Data> {
255    const OPCODE: Opcode = Opcode::none::<Data>(GROUP, NUM);
256}
rustix/ioctl/patterns.rs

rustix/ioctl/
patterns.rs
