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