diff options
Diffstat (limited to 'rust/kernel/types.rs')
| -rw-r--r-- | rust/kernel/types.rs | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs index fdb778e65d79..aa77bad9bce4 100644 --- a/rust/kernel/types.rs +++ b/rust/kernel/types.rs @@ -46,6 +46,25 @@ pub trait ForeignOwnable: Sized { /// Additionally, all instances (if any) of values returned by [`ForeignOwnable::borrow`] for /// this object must have been dropped. unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self; + + /// Tries to convert a foreign-owned object back to a Rust-owned one. + /// + /// A convenience wrapper over [`ForeignOwnable::from_foreign`] that returns [`None`] if `ptr` + /// is null. + /// + /// # Safety + /// + /// `ptr` must either be null or satisfy the safety requirements for + /// [`ForeignOwnable::from_foreign`]. + unsafe fn try_from_foreign(ptr: *const core::ffi::c_void) -> Option<Self> { + if ptr.is_null() { + None + } else { + // SAFETY: Since `ptr` is not null here, then `ptr` satisfies the safety requirements + // of `from_foreign` given the safety requirements of this function. + unsafe { Some(Self::from_foreign(ptr)) } + } + } } impl<T: 'static> ForeignOwnable for Box<T> { @@ -90,6 +109,7 @@ impl ForeignOwnable for () { /// /// In the example below, we have multiple exit paths and we want to log regardless of which one is /// taken: +/// /// ``` /// # use kernel::types::ScopeGuard; /// fn example1(arg: bool) { @@ -108,6 +128,7 @@ impl ForeignOwnable for () { /// /// In the example below, we want to log the same message on all early exits but a different one on /// the main exit path: +/// /// ``` /// # use kernel::types::ScopeGuard; /// fn example2(arg: bool) { @@ -129,6 +150,7 @@ impl ForeignOwnable for () { /// /// In the example below, we need a mutable object (the vector) to be accessible within the log /// function, so we wrap it in the [`ScopeGuard`]: +/// /// ``` /// # use kernel::types::ScopeGuard; /// fn example3(arg: bool) -> Result { |