| //! UEFI-specific extensions to the primitives in `std::env` module |
| |
| #![unstable(feature = "uefi_std", issue = "100499")] |
| |
| use crate::sync::atomic::{AtomicBool, AtomicPtr, Ordering}; |
| use crate::{ffi::c_void, ptr::NonNull}; |
| |
| static SYSTEM_TABLE: AtomicPtr<c_void> = AtomicPtr::new(crate::ptr::null_mut()); |
| static IMAGE_HANDLE: AtomicPtr<c_void> = AtomicPtr::new(crate::ptr::null_mut()); |
| // Flag to check if BootServices are still valid. |
| // Start with assuming that they are not available |
| static BOOT_SERVICES_FLAG: AtomicBool = AtomicBool::new(false); |
| |
| /// Initializes the global System Table and Image Handle pointers. |
| /// |
| /// The standard library requires access to the UEFI System Table and the Application Image Handle |
| /// to operate. Those are provided to UEFI Applications via their application entry point. By |
| /// calling `init_globals()`, those pointers are retained by the standard library for future use. |
| /// Thus this function must be called before any of the standard library services are used. |
| /// |
| /// The pointers are never exposed to any entity outside of this application and it is guaranteed |
| /// that, once the application exited, these pointers are never dereferenced again. |
| /// |
| /// Callers are required to ensure the pointers are valid for the entire lifetime of this |
| /// application. In particular, UEFI Boot Services must not be exited while an application with the |
| /// standard library is loaded. |
| /// |
| /// # SAFETY |
| /// Calling this function more than once will panic |
| pub(crate) unsafe fn init_globals(handle: NonNull<c_void>, system_table: NonNull<c_void>) { |
| IMAGE_HANDLE |
| .compare_exchange( |
| crate::ptr::null_mut(), |
| handle.as_ptr(), |
| Ordering::Release, |
| Ordering::Acquire, |
| ) |
| .unwrap(); |
| SYSTEM_TABLE |
| .compare_exchange( |
| crate::ptr::null_mut(), |
| system_table.as_ptr(), |
| Ordering::Release, |
| Ordering::Acquire, |
| ) |
| .unwrap(); |
| BOOT_SERVICES_FLAG.store(true, Ordering::Release) |
| } |
| |
| /// Get the SystemTable Pointer. |
| /// If you want to use `BootServices` then please use [`boot_services`] as it performs some |
| /// additional checks. |
| /// |
| /// Note: This function panics if the System Table or Image Handle is not initialized |
| pub fn system_table() -> NonNull<c_void> { |
| try_system_table().unwrap() |
| } |
| |
| /// Get the ImageHandle Pointer. |
| /// |
| /// Note: This function panics if the System Table or Image Handle is not initialized |
| pub fn image_handle() -> NonNull<c_void> { |
| try_image_handle().unwrap() |
| } |
| |
| /// Get the BootServices Pointer. |
| /// This function also checks if `ExitBootServices` has already been called. |
| pub fn boot_services() -> Option<NonNull<c_void>> { |
| if BOOT_SERVICES_FLAG.load(Ordering::Acquire) { |
| let system_table: NonNull<r_efi::efi::SystemTable> = try_system_table()?.cast(); |
| let boot_services = unsafe { (*system_table.as_ptr()).boot_services }; |
| NonNull::new(boot_services).map(|x| x.cast()) |
| } else { |
| None |
| } |
| } |
| |
| /// Get the SystemTable Pointer. |
| /// This function is mostly intended for places where panic is not an option |
| pub(crate) fn try_system_table() -> Option<NonNull<c_void>> { |
| NonNull::new(SYSTEM_TABLE.load(Ordering::Acquire)) |
| } |
| |
| /// Get the SystemHandle Pointer. |
| /// This function is mostly intended for places where panicking is not an option |
| pub(crate) fn try_image_handle() -> Option<NonNull<c_void>> { |
| NonNull::new(IMAGE_HANDLE.load(Ordering::Acquire)) |
| } |
| |
| pub(crate) fn disable_boot_services() { |
| BOOT_SERVICES_FLAG.store(false, Ordering::Release) |
| } |