1 // SPDX-License-Identifier: GPL-2.0 OR MIT 2 3 //! DRM File objects. 4 //! 5 //! C header: [`include/drm/drm_file.h`](srctree/include/drm/drm_file.h) 6 7 use crate::{ 8 bindings, 9 drm, 10 error::Result, 11 prelude::*, 12 types::Opaque, // 13 }; 14 use core::{ 15 marker::PhantomData, 16 pin::Pin, // 17 }; 18 19 /// Trait that must be implemented by DRM drivers to represent a DRM File (a client instance). 20 pub trait DriverFile { 21 /// The parent `Driver` implementation for this `DriverFile`. 22 type Driver: drm::Driver; 23 24 /// Open a new file (called when a client opens the DRM device). 25 fn open(device: &drm::Device<Self::Driver>) -> Result<Pin<KBox<Self>>>; 26 } 27 28 /// An open DRM File. 29 /// 30 /// # Invariants 31 /// 32 /// `self.0` is a valid instance of a `struct drm_file`. 33 #[repr(transparent)] 34 pub struct File<T: DriverFile>(Opaque<bindings::drm_file>, PhantomData<T>); 35 36 impl<T: DriverFile> File<T> { 37 #[doc(hidden)] 38 /// Not intended to be called externally, except via declare_drm_ioctls!() 39 /// 40 /// # Safety 41 /// 42 /// `raw_file` must be a valid pointer to an open `struct drm_file`, opened through `T::open`. 43 pub unsafe fn from_raw<'a>(ptr: *mut bindings::drm_file) -> &'a File<T> { 44 // SAFETY: `raw_file` is valid by the safety requirements of this function. 45 unsafe { &*ptr.cast() } 46 } 47 48 pub(super) fn as_raw(&self) -> *mut bindings::drm_file { 49 self.0.get() 50 } 51 52 fn driver_priv(&self) -> *mut T { 53 // SAFETY: By the type invariants of `Self`, `self.as_raw()` is always valid. 54 unsafe { (*self.as_raw()).driver_priv }.cast() 55 } 56 57 /// Return a pinned reference to the driver file structure. 58 pub fn inner(&self) -> Pin<&T> { 59 // SAFETY: By the type invariant the pointer `self.as_raw()` points to a valid and opened 60 // `struct drm_file`, hence `driver_priv` has been properly initialized by `open_callback`. 61 unsafe { Pin::new_unchecked(&*(self.driver_priv())) } 62 } 63 64 /// The open callback of a `struct drm_file`. 65 pub(crate) extern "C" fn open_callback( 66 raw_dev: *mut bindings::drm_device, 67 raw_file: *mut bindings::drm_file, 68 ) -> core::ffi::c_int { 69 // SAFETY: A callback from `struct drm_driver::open` guarantees that 70 // - `raw_dev` is valid pointer to a `struct drm_device`, 71 // - the corresponding `struct drm_device` has been registered. 72 let drm = unsafe { drm::Device::from_raw(raw_dev) }; 73 74 // SAFETY: `raw_file` is a valid pointer to a `struct drm_file`. 75 let file = unsafe { File::<T>::from_raw(raw_file) }; 76 77 let inner = match T::open(drm) { 78 Err(e) => { 79 return e.to_errno(); 80 } 81 Ok(i) => i, 82 }; 83 84 // SAFETY: This pointer is treated as pinned, and the Drop guarantee is upheld in 85 // `postclose_callback()`. 86 let driver_priv = KBox::into_raw(unsafe { Pin::into_inner_unchecked(inner) }); 87 88 // SAFETY: By the type invariants of `Self`, `self.as_raw()` is always valid. 89 unsafe { (*file.as_raw()).driver_priv = driver_priv.cast() }; 90 91 0 92 } 93 94 /// The postclose callback of a `struct drm_file`. 95 pub(crate) extern "C" fn postclose_callback( 96 _raw_dev: *mut bindings::drm_device, 97 raw_file: *mut bindings::drm_file, 98 ) { 99 // SAFETY: This reference won't escape this function 100 let file = unsafe { File::<T>::from_raw(raw_file) }; 101 102 // SAFETY: `file.driver_priv` has been created in `open_callback` through `KBox::into_raw`. 103 let _ = unsafe { KBox::from_raw(file.driver_priv()) }; 104 } 105 } 106 107 impl<T: DriverFile> super::private::Sealed for File<T> {} 108