| use core::cell::RefCell; |
| use core::marker::Freeze; |
| use core::mem::MaybeUninit; |
| use core::num::NonZero; |
| use core::ptr; |
| use core::ptr::*; |
| use std::fmt::{Debug, Display}; |
| |
| #[test] |
| fn test_const_from_raw_parts() { |
| const SLICE: &[u8] = &[1, 2, 3, 4]; |
| const FROM_RAW: &[u8] = unsafe { &*slice_from_raw_parts(SLICE.as_ptr(), SLICE.len()) }; |
| assert_eq!(SLICE, FROM_RAW); |
| |
| let slice = &[1, 2, 3, 4, 5]; |
| let from_raw = unsafe { &*slice_from_raw_parts(slice.as_ptr(), 2) }; |
| assert_eq!(&slice[..2], from_raw); |
| } |
| |
| #[test] |
| fn test() { |
| unsafe { |
| #[repr(C)] |
| struct Pair { |
| fst: isize, |
| snd: isize, |
| } |
| let mut p = Pair { fst: 10, snd: 20 }; |
| let pptr: *mut Pair = addr_of_mut!(p); |
| let iptr: *mut isize = pptr as *mut isize; |
| assert_eq!(*iptr, 10); |
| *iptr = 30; |
| assert_eq!(*iptr, 30); |
| assert_eq!(p.fst, 30); |
| |
| *pptr = Pair { fst: 50, snd: 60 }; |
| assert_eq!(*iptr, 50); |
| assert_eq!(p.fst, 50); |
| assert_eq!(p.snd, 60); |
| |
| let v0 = vec![32000u16, 32001u16, 32002u16]; |
| let mut v1 = vec![0u16, 0u16, 0u16]; |
| |
| copy(v0.as_ptr().offset(1), v1.as_mut_ptr().offset(1), 1); |
| assert!(v1[0] == 0u16 && v1[1] == 32001u16 && v1[2] == 0u16); |
| copy(v0.as_ptr().offset(2), v1.as_mut_ptr(), 1); |
| assert!(v1[0] == 32002u16 && v1[1] == 32001u16 && v1[2] == 0u16); |
| copy(v0.as_ptr(), v1.as_mut_ptr().offset(2), 1); |
| assert!(v1[0] == 32002u16 && v1[1] == 32001u16 && v1[2] == 32000u16); |
| } |
| } |
| |
| #[test] |
| fn test_is_null() { |
| let p: *const isize = null(); |
| assert!(p.is_null()); |
| |
| let q = p.wrapping_offset(1); |
| assert!(!q.is_null()); |
| |
| let mp: *mut isize = null_mut(); |
| assert!(mp.is_null()); |
| |
| let mq = mp.wrapping_offset(1); |
| assert!(!mq.is_null()); |
| |
| // Pointers to unsized types -- slices |
| let s: &mut [u8] = &mut [1, 2, 3]; |
| let cs: *const [u8] = s; |
| assert!(!cs.is_null()); |
| |
| let ms: *mut [u8] = s; |
| assert!(!ms.is_null()); |
| |
| let cz: *const [u8] = &[]; |
| assert!(!cz.is_null()); |
| |
| let mz: *mut [u8] = &mut []; |
| assert!(!mz.is_null()); |
| |
| let ncs: *const [u8] = null::<[u8; 3]>(); |
| assert!(ncs.is_null()); |
| |
| let nms: *mut [u8] = null_mut::<[u8; 3]>(); |
| assert!(nms.is_null()); |
| |
| // Pointers to unsized types -- trait objects |
| let ci: *const dyn ToString = &3; |
| assert!(!ci.is_null()); |
| |
| let mi: *mut dyn ToString = &mut 3; |
| assert!(!mi.is_null()); |
| |
| let nci: *const dyn ToString = null::<isize>(); |
| assert!(nci.is_null()); |
| |
| let nmi: *mut dyn ToString = null_mut::<isize>(); |
| assert!(nmi.is_null()); |
| |
| unsafe extern "C" { |
| type Extern; |
| } |
| let ec: *const Extern = null::<Extern>(); |
| assert!(ec.is_null()); |
| |
| let em: *mut Extern = null_mut::<Extern>(); |
| assert!(em.is_null()); |
| } |
| |
| #[test] |
| fn test_as_ref() { |
| unsafe { |
| let p: *const isize = null(); |
| assert_eq!(p.as_ref(), None); |
| |
| let q: *const isize = &2; |
| assert_eq!(q.as_ref().unwrap(), &2); |
| |
| let p: *mut isize = null_mut(); |
| assert_eq!(p.as_ref(), None); |
| |
| let q: *mut isize = &mut 2; |
| assert_eq!(q.as_ref().unwrap(), &2); |
| |
| // Lifetime inference |
| let u = 2isize; |
| { |
| let p = &u as *const isize; |
| assert_eq!(p.as_ref().unwrap(), &2); |
| } |
| |
| // Pointers to unsized types -- slices |
| let s: &mut [u8] = &mut [1, 2, 3]; |
| let cs: *const [u8] = s; |
| assert_eq!(cs.as_ref(), Some(&*s)); |
| |
| let ms: *mut [u8] = s; |
| assert_eq!(ms.as_ref(), Some(&*s)); |
| |
| let cz: *const [u8] = &[]; |
| assert_eq!(cz.as_ref(), Some(&[][..])); |
| |
| let mz: *mut [u8] = &mut []; |
| assert_eq!(mz.as_ref(), Some(&[][..])); |
| |
| let ncs: *const [u8] = null::<[u8; 3]>(); |
| assert_eq!(ncs.as_ref(), None); |
| |
| let nms: *mut [u8] = null_mut::<[u8; 3]>(); |
| assert_eq!(nms.as_ref(), None); |
| |
| // Pointers to unsized types -- trait objects |
| let ci: *const dyn ToString = &3; |
| assert!(ci.as_ref().is_some()); |
| |
| let mi: *mut dyn ToString = &mut 3; |
| assert!(mi.as_ref().is_some()); |
| |
| let nci: *const dyn ToString = null::<isize>(); |
| assert!(nci.as_ref().is_none()); |
| |
| let nmi: *mut dyn ToString = null_mut::<isize>(); |
| assert!(nmi.as_ref().is_none()); |
| } |
| } |
| |
| #[test] |
| fn test_as_mut() { |
| unsafe { |
| let p: *mut isize = null_mut(); |
| assert!(p.as_mut() == None); |
| |
| let q: *mut isize = &mut 2; |
| assert!(q.as_mut().unwrap() == &mut 2); |
| |
| // Lifetime inference |
| let mut u = 2isize; |
| { |
| let p = &mut u as *mut isize; |
| assert!(p.as_mut().unwrap() == &mut 2); |
| } |
| |
| // Pointers to unsized types -- slices |
| let s: &mut [u8] = &mut [1, 2, 3]; |
| let ms: *mut [u8] = s; |
| assert_eq!(ms.as_mut(), Some(&mut [1, 2, 3][..])); |
| |
| let mz: *mut [u8] = &mut []; |
| assert_eq!(mz.as_mut(), Some(&mut [][..])); |
| |
| let nms: *mut [u8] = null_mut::<[u8; 3]>(); |
| assert_eq!(nms.as_mut(), None); |
| |
| // Pointers to unsized types -- trait objects |
| let mi: *mut dyn ToString = &mut 3; |
| assert!(mi.as_mut().is_some()); |
| |
| let nmi: *mut dyn ToString = null_mut::<isize>(); |
| assert!(nmi.as_mut().is_none()); |
| } |
| } |
| |
| #[test] |
| fn test_ptr_addition() { |
| unsafe { |
| let xs = vec![5; 16]; |
| let mut ptr = xs.as_ptr(); |
| let end = ptr.offset(16); |
| |
| while ptr < end { |
| assert_eq!(*ptr, 5); |
| ptr = ptr.offset(1); |
| } |
| |
| let mut xs_mut = xs; |
| let mut m_ptr = xs_mut.as_mut_ptr(); |
| let m_end = m_ptr.offset(16); |
| |
| while m_ptr < m_end { |
| *m_ptr += 5; |
| m_ptr = m_ptr.offset(1); |
| } |
| |
| assert!(xs_mut == vec![10; 16]); |
| } |
| } |
| |
| #[test] |
| fn test_ptr_subtraction() { |
| unsafe { |
| let xs = vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9]; |
| let mut idx = 9; |
| let ptr = xs.as_ptr(); |
| |
| while idx >= 0 { |
| assert_eq!(*(ptr.offset(idx as isize)), idx as isize); |
| idx = idx - 1; |
| } |
| |
| let mut xs_mut = xs; |
| let m_start = xs_mut.as_mut_ptr(); |
| let mut m_ptr = m_start.offset(9); |
| |
| loop { |
| *m_ptr += *m_ptr; |
| if m_ptr == m_start { |
| break; |
| } |
| m_ptr = m_ptr.offset(-1); |
| } |
| |
| assert_eq!(xs_mut, [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]); |
| } |
| } |
| |
| #[test] |
| fn test_set_memory() { |
| let mut xs = [0u8; 20]; |
| let ptr = xs.as_mut_ptr(); |
| unsafe { |
| write_bytes(ptr, 5u8, xs.len()); |
| } |
| assert!(xs == [5u8; 20]); |
| } |
| |
| #[test] |
| fn test_set_memory_const() { |
| const XS: [u8; 20] = { |
| let mut xs = [0u8; 20]; |
| let ptr = xs.as_mut_ptr(); |
| unsafe { |
| ptr.write_bytes(5u8, xs.len()); |
| } |
| xs |
| }; |
| |
| assert!(XS == [5u8; 20]); |
| } |
| |
| #[test] |
| fn test_unsized_nonnull() { |
| let xs: &[i32] = &[1, 2, 3]; |
| let ptr = unsafe { NonNull::new_unchecked(xs as *const [i32] as *mut [i32]) }; |
| let ys = unsafe { ptr.as_ref() }; |
| let zs: &[i32] = &[1, 2, 3]; |
| assert!(ys == zs); |
| } |
| |
| #[test] |
| fn test_const_nonnull_new() { |
| const { |
| assert!(NonNull::new(core::ptr::null_mut::<()>()).is_none()); |
| |
| let value = &mut 0u32; |
| let mut ptr = NonNull::new(value).unwrap(); |
| unsafe { *ptr.as_mut() = 42 }; |
| |
| let reference = unsafe { &*ptr.as_ref() }; |
| assert!(*reference == *value); |
| assert!(*reference == 42); |
| }; |
| } |
| |
| #[test] |
| #[cfg(unix)] // printf may not be available on other platforms |
| #[allow(deprecated)] // For SipHasher |
| #[allow(unpredictable_function_pointer_comparisons)] |
| pub fn test_variadic_fnptr() { |
| use core::ffi; |
| use core::hash::{Hash, SipHasher}; |
| unsafe extern "C" { |
| // This needs to use the correct function signature even though it isn't called as some |
| // codegen backends make it UB to declare a function with multiple conflicting signatures |
| // (like LLVM) while others straight up return an error (like Cranelift). |
| fn printf(_: *const ffi::c_char, ...) -> ffi::c_int; |
| } |
| let p: unsafe extern "C" fn(*const ffi::c_char, ...) -> ffi::c_int = printf; |
| let q = p.clone(); |
| assert_eq!(p, q); |
| assert!(!(p < q)); |
| let mut s = SipHasher::new(); |
| assert_eq!(p.hash(&mut s), q.hash(&mut s)); |
| } |
| |
| #[test] |
| fn write_unaligned_drop() { |
| thread_local! { |
| static DROPS: RefCell<Vec<u32>> = RefCell::new(Vec::new()); |
| } |
| |
| struct Dropper(u32); |
| |
| impl Drop for Dropper { |
| fn drop(&mut self) { |
| DROPS.with(|d| d.borrow_mut().push(self.0)); |
| } |
| } |
| |
| { |
| let c = Dropper(0); |
| let mut t = Dropper(1); |
| unsafe { |
| write_unaligned(&mut t, c); |
| } |
| } |
| DROPS.with(|d| assert_eq!(*d.borrow(), [0])); |
| } |
| |
| #[test] |
| fn align_offset_zst() { |
| // For pointers of stride = 0, the pointer is already aligned or it cannot be aligned at |
| // all, because no amount of elements will align the pointer. |
| let mut p = 1; |
| while p < 1024 { |
| assert_eq!(ptr::without_provenance::<()>(p).align_offset(p), 0); |
| if p != 1 { |
| assert_eq!(ptr::without_provenance::<()>(p + 1).align_offset(p), !0); |
| } |
| p = (p + 1).next_power_of_two(); |
| } |
| } |
| |
| #[test] |
| fn align_offset_stride_one() { |
| // For pointers of stride = 1, the pointer can always be aligned. The offset is equal to |
| // number of bytes. |
| let mut align = 1; |
| while align < 1024 { |
| for ptr in 1..2 * align { |
| let expected = ptr % align; |
| let offset = if expected == 0 { 0 } else { align - expected }; |
| assert_eq!( |
| ptr::without_provenance::<u8>(ptr).align_offset(align), |
| offset, |
| "ptr = {}, align = {}, size = 1", |
| ptr, |
| align |
| ); |
| } |
| align = (align + 1).next_power_of_two(); |
| } |
| } |
| |
| #[test] |
| fn align_offset_various_strides() { |
| unsafe fn test_stride<T>(ptr: *const T, align: usize) -> bool { |
| let numptr = ptr as usize; |
| let mut expected = usize::MAX; |
| // Naive but definitely correct way to find the *first* aligned element of stride::<T>. |
| for el in 0..align { |
| if (numptr + el * size_of::<T>()) % align == 0 { |
| expected = el; |
| break; |
| } |
| } |
| let got = ptr.align_offset(align); |
| if got != expected { |
| eprintln!( |
| "aligning {:p} (with stride of {}) to {}, expected {}, got {}", |
| ptr, |
| size_of::<T>(), |
| align, |
| expected, |
| got |
| ); |
| return true; |
| } |
| return false; |
| } |
| |
| // For pointers of stride != 1, we verify the algorithm against the naivest possible |
| // implementation |
| let mut align = 1; |
| let mut x = false; |
| // Miri is too slow |
| let limit = if cfg!(miri) { 32 } else { 1024 }; |
| while align < limit { |
| for ptr in 1usize..4 * align { |
| unsafe { |
| #[repr(packed)] |
| struct A3(#[allow(dead_code)] u16, #[allow(dead_code)] u8); |
| x |= test_stride::<A3>(ptr::without_provenance::<A3>(ptr), align); |
| |
| struct A4(#[allow(dead_code)] u32); |
| x |= test_stride::<A4>(ptr::without_provenance::<A4>(ptr), align); |
| |
| #[repr(packed)] |
| struct A5(#[allow(dead_code)] u32, #[allow(dead_code)] u8); |
| x |= test_stride::<A5>(ptr::without_provenance::<A5>(ptr), align); |
| |
| #[repr(packed)] |
| struct A6(#[allow(dead_code)] u32, #[allow(dead_code)] u16); |
| x |= test_stride::<A6>(ptr::without_provenance::<A6>(ptr), align); |
| |
| #[repr(packed)] |
| struct A7(#[allow(dead_code)] u32, #[allow(dead_code)] u16, #[allow(dead_code)] u8); |
| x |= test_stride::<A7>(ptr::without_provenance::<A7>(ptr), align); |
| |
| #[repr(packed)] |
| struct A8(#[allow(dead_code)] u32, #[allow(dead_code)] u32); |
| x |= test_stride::<A8>(ptr::without_provenance::<A8>(ptr), align); |
| |
| #[repr(packed)] |
| struct A9(#[allow(dead_code)] u32, #[allow(dead_code)] u32, #[allow(dead_code)] u8); |
| x |= test_stride::<A9>(ptr::without_provenance::<A9>(ptr), align); |
| |
| #[repr(packed)] |
| struct A10( |
| #[allow(dead_code)] u32, |
| #[allow(dead_code)] u32, |
| #[allow(dead_code)] u16, |
| ); |
| x |= test_stride::<A10>(ptr::without_provenance::<A10>(ptr), align); |
| |
| x |= test_stride::<u32>(ptr::without_provenance::<u32>(ptr), align); |
| x |= test_stride::<u128>(ptr::without_provenance::<u128>(ptr), align); |
| } |
| } |
| align = (align + 1).next_power_of_two(); |
| } |
| assert!(!x); |
| } |
| |
| #[test] |
| fn align_offset_issue_103361() { |
| #[cfg(target_pointer_width = "64")] |
| const SIZE: usize = 1 << 47; |
| #[cfg(target_pointer_width = "32")] |
| const SIZE: usize = 1 << 30; |
| #[cfg(target_pointer_width = "16")] |
| const SIZE: usize = 1 << 13; |
| struct HugeSize(#[allow(dead_code)] [u8; SIZE - 1]); |
| let _ = ptr::without_provenance::<HugeSize>(SIZE).align_offset(SIZE); |
| } |
| |
| #[test] |
| fn is_aligned() { |
| let data = 42; |
| let ptr: *const i32 = &data; |
| assert!(ptr.is_aligned()); |
| assert!(ptr.is_aligned_to(1)); |
| assert!(ptr.is_aligned_to(2)); |
| assert!(ptr.is_aligned_to(4)); |
| assert!(ptr.wrapping_byte_add(2).is_aligned_to(1)); |
| assert!(ptr.wrapping_byte_add(2).is_aligned_to(2)); |
| assert!(!ptr.wrapping_byte_add(2).is_aligned_to(4)); |
| |
| // At runtime either `ptr` or `ptr+1` is aligned to 8. |
| assert_ne!(ptr.is_aligned_to(8), ptr.wrapping_add(1).is_aligned_to(8)); |
| } |
| |
| #[test] |
| fn offset_from() { |
| let mut a = [0; 5]; |
| let ptr1: *mut i32 = &mut a[1]; |
| let ptr2: *mut i32 = &mut a[3]; |
| unsafe { |
| assert_eq!(ptr2.offset_from(ptr1), 2); |
| assert_eq!(ptr1.offset_from(ptr2), -2); |
| assert_eq!(ptr1.offset(2), ptr2); |
| assert_eq!(ptr2.offset(-2), ptr1); |
| } |
| } |
| |
| #[test] |
| fn ptr_metadata() { |
| struct Unit; |
| struct Pair<A, B: ?Sized>(A, B); |
| unsafe extern "C" { |
| type Extern; |
| } |
| let () = metadata(&()); |
| let () = metadata(&Unit); |
| let () = metadata(&4_u32); |
| let () = metadata(&String::new()); |
| let () = metadata(&Some(4_u32)); |
| let () = metadata(&ptr_metadata); |
| let () = metadata(&|| {}); |
| let () = metadata(&[4, 7]); |
| let () = metadata(&(4, String::new())); |
| let () = metadata(&Pair(4, String::new())); |
| let () = metadata(ptr::null::<()>() as *const Extern); |
| let () = metadata(ptr::null::<()>() as *const <&u32 as std::ops::Deref>::Target); |
| |
| assert_eq!(metadata("foo"), 3_usize); |
| assert_eq!(metadata(&[4, 7][..]), 2_usize); |
| |
| let dst_struct: &Pair<bool, [u8]> = &Pair(true, [0x66, 0x6F, 0x6F]); |
| assert_eq!(metadata(dst_struct), 3_usize); |
| unsafe { |
| let dst_struct: &Pair<bool, str> = std::mem::transmute(dst_struct); |
| assert_eq!(&dst_struct.1, "foo"); |
| assert_eq!(metadata(dst_struct), 3_usize); |
| } |
| |
| let vtable_1: DynMetadata<dyn Debug> = metadata(&4_u16 as &dyn Debug); |
| let vtable_2: DynMetadata<dyn Display> = metadata(&4_u16 as &dyn Display); |
| let vtable_3: DynMetadata<dyn Display> = metadata(&4_u32 as &dyn Display); |
| let vtable_4: DynMetadata<dyn Display> = |
| metadata(&Pair(true, 7_u32) as &Pair<bool, dyn Display>); |
| unsafe { |
| let address_1: *const () = std::mem::transmute(vtable_1); |
| let address_2: *const () = std::mem::transmute(vtable_2); |
| let address_3: *const () = std::mem::transmute(vtable_3); |
| let address_4: *const () = std::mem::transmute(vtable_4); |
| // Different trait => different vtable pointer |
| assert_ne!(address_1, address_2); |
| // Different erased type => different vtable pointer |
| assert_ne!(address_2, address_3); |
| // Same erased type and same trait => same vtable pointer. |
| // This is *not guaranteed*, so we skip it in Miri. |
| if !cfg!(miri) { |
| assert_eq!(address_3, address_4); |
| } |
| } |
| } |
| |
| #[test] |
| fn ptr_metadata_bounds() { |
| fn metadata_eq_method_address<T: ?Sized>() -> usize { |
| // The `Metadata` associated type has an `Ord` bound, so this is valid: |
| <<T as Pointee>::Metadata as PartialEq>::eq as usize |
| } |
| // "Synthetic" trait impls generated by the compiler like those of `Pointee` |
| // are not checked for bounds of associated type. |
| // So with a buggy core we could have both: |
| // * `<dyn Display as Pointee>::Metadata == DynMetadata` |
| // * `DynMetadata: !PartialEq` |
| // … and cause an ICE here: |
| metadata_eq_method_address::<dyn Display>(); |
| |
| // For this reason, let’s check here that bounds are satisfied: |
| |
| let _ = static_assert_expected_bounds_for_metadata::<()>; |
| let _ = static_assert_expected_bounds_for_metadata::<usize>; |
| let _ = static_assert_expected_bounds_for_metadata::<DynMetadata<dyn Display>>; |
| fn _static_assert_associated_type<T: ?Sized>() { |
| let _ = static_assert_expected_bounds_for_metadata::<<T as Pointee>::Metadata>; |
| } |
| |
| fn static_assert_expected_bounds_for_metadata<Meta>() |
| where |
| // Keep this in sync with the associated type in `library/core/src/ptr/metadata.rs` |
| Meta: Debug + Copy + Send + Sync + Ord + std::hash::Hash + Unpin + Freeze, |
| { |
| } |
| } |
| |
| #[test] |
| fn pointee_metadata_debug() { |
| assert_eq!("()", format!("{:?}", metadata::<u32>(&17))); |
| assert_eq!("2", format!("{:?}", metadata::<[u32]>(&[19, 23]))); |
| let for_dyn = format!("{:?}", metadata::<dyn Debug>(&29)); |
| assert!(for_dyn.starts_with("DynMetadata(0x"), "{:?}", for_dyn); |
| } |
| |
| #[test] |
| fn dyn_metadata() { |
| #[derive(Debug)] |
| #[repr(align(32))] |
| struct Something(#[allow(dead_code)] [u8; 47]); |
| |
| let value = Something([0; 47]); |
| let trait_object: &dyn Debug = &value; |
| let meta = metadata(trait_object); |
| |
| assert_eq!(meta.size_of(), 64); |
| assert_eq!(meta.size_of(), size_of::<Something>()); |
| assert_eq!(meta.align_of(), 32); |
| assert_eq!(meta.align_of(), align_of::<Something>()); |
| assert_eq!(meta.layout(), std::alloc::Layout::new::<Something>()); |
| |
| assert!(format!("{meta:?}").starts_with("DynMetadata(0x")); |
| } |
| |
| #[test] |
| fn from_raw_parts() { |
| let mut value = 5_u32; |
| let address = &mut value as *mut _ as *mut (); |
| let trait_object: &dyn Display = &mut value; |
| let vtable = metadata(trait_object); |
| let trait_object = NonNull::from(trait_object); |
| |
| assert_eq!(ptr::from_raw_parts(address, vtable), trait_object.as_ptr()); |
| assert_eq!(ptr::from_raw_parts_mut(address, vtable), trait_object.as_ptr()); |
| assert_eq!(NonNull::from_raw_parts(NonNull::new(address).unwrap(), vtable), trait_object); |
| |
| let mut array = [5_u32, 5, 5, 5, 5]; |
| let address = &mut array as *mut _ as *mut (); |
| let array_ptr = NonNull::from(&mut array); |
| let slice_ptr = NonNull::from(&mut array[..]); |
| |
| assert_eq!(ptr::from_raw_parts(address, ()), array_ptr.as_ptr()); |
| assert_eq!(ptr::from_raw_parts_mut(address, ()), array_ptr.as_ptr()); |
| assert_eq!(NonNull::from_raw_parts(NonNull::new(address).unwrap(), ()), array_ptr); |
| |
| assert_eq!(ptr::from_raw_parts(address, 5), slice_ptr.as_ptr()); |
| assert_eq!(ptr::from_raw_parts_mut(address, 5), slice_ptr.as_ptr()); |
| assert_eq!(NonNull::from_raw_parts(NonNull::new(address).unwrap(), 5), slice_ptr); |
| } |
| |
| #[test] |
| fn thin_box() { |
| let foo = ThinBox::<dyn Display>::new(4); |
| assert_eq!(foo.to_string(), "4"); |
| drop(foo); |
| let bar = ThinBox::<dyn Display>::new(7); |
| assert_eq!(bar.to_string(), "7"); |
| |
| // A slightly more interesting library that could be built on top of metadata APIs. |
| // |
| // * It could be generalized to any `T:Â ?Sized` (not just trait object) |
| // if `{size,align}_of_for_meta<T:Â ?Sized>(T::Metadata)` are added. |
| // * Constructing a `ThinBox` without consuming and deallocating a `Box` |
| // requires either the unstable `Unsize` marker trait, |
| // or taking `&dyn T` and restricting to `T: Copy`. |
| |
| use std::alloc::*; |
| use std::marker::PhantomData; |
| |
| struct ThinBox<T> |
| where |
| T: ?Sized + Pointee<Metadata = DynMetadata<T>>, |
| { |
| ptr: NonNull<DynMetadata<T>>, |
| phantom: PhantomData<T>, |
| } |
| |
| impl<T> ThinBox<T> |
| where |
| T: ?Sized + Pointee<Metadata = DynMetadata<T>>, |
| { |
| pub fn new<Value: std::marker::Unsize<T>>(value: Value) -> Self { |
| let unsized_: &T = &value; |
| let meta = metadata(unsized_); |
| let meta_layout = Layout::for_value(&meta); |
| let value_layout = Layout::for_value(&value); |
| let (layout, offset) = meta_layout.extend(value_layout).unwrap(); |
| // `DynMetadata` is pointer-sized: |
| assert!(layout.size() > 0); |
| // If `ThinBox<T>` is generalized to any `T: ?Sized`, |
| // handle ZSTs with a dangling pointer without going through `alloc()`, |
| // like `Box<T>` does. |
| unsafe { |
| let ptr = NonNull::new(alloc(layout)) |
| .unwrap_or_else(|| handle_alloc_error(layout)) |
| .cast::<DynMetadata<T>>(); |
| ptr.as_ptr().write(meta); |
| ptr.as_ptr().byte_add(offset).cast::<Value>().write(value); |
| Self { ptr, phantom: PhantomData } |
| } |
| } |
| |
| fn meta(&self) -> DynMetadata<T> { |
| unsafe { *self.ptr.as_ref() } |
| } |
| |
| fn layout(&self) -> (Layout, usize) { |
| let meta = self.meta(); |
| Layout::for_value(&meta).extend(meta.layout()).unwrap() |
| } |
| |
| fn value_ptr(&self) -> *const T { |
| let (_, offset) = self.layout(); |
| let data_ptr = unsafe { self.ptr.cast::<u8>().as_ptr().add(offset) }; |
| ptr::from_raw_parts(data_ptr, self.meta()) |
| } |
| |
| fn value_mut_ptr(&mut self) -> *mut T { |
| let (_, offset) = self.layout(); |
| // FIXME: can this line be shared with the same in `value_ptr()` |
| // without upsetting Stacked Borrows? |
| let data_ptr = unsafe { self.ptr.cast::<u8>().as_ptr().add(offset) }; |
| from_raw_parts_mut(data_ptr, self.meta()) |
| } |
| } |
| |
| impl<T> std::ops::Deref for ThinBox<T> |
| where |
| T: ?Sized + Pointee<Metadata = DynMetadata<T>>, |
| { |
| type Target = T; |
| |
| fn deref(&self) -> &T { |
| unsafe { &*self.value_ptr() } |
| } |
| } |
| |
| impl<T> std::ops::DerefMut for ThinBox<T> |
| where |
| T: ?Sized + Pointee<Metadata = DynMetadata<T>>, |
| { |
| fn deref_mut(&mut self) -> &mut T { |
| unsafe { &mut *self.value_mut_ptr() } |
| } |
| } |
| |
| impl<T> std::ops::Drop for ThinBox<T> |
| where |
| T: ?Sized + Pointee<Metadata = DynMetadata<T>>, |
| { |
| fn drop(&mut self) { |
| let (layout, _) = self.layout(); |
| unsafe { |
| drop_in_place::<T>(&mut **self); |
| dealloc(self.ptr.cast().as_ptr(), layout); |
| } |
| } |
| } |
| } |
| |
| #[test] |
| fn nonnull_tagged_pointer_with_provenance() { |
| let raw_pointer = Box::into_raw(Box::new(10)); |
| |
| let mut p = TaggedPointer::new(raw_pointer).unwrap(); |
| assert_eq!(p.tag(), 0); |
| |
| p.set_tag(1); |
| assert_eq!(p.tag(), 1); |
| assert_eq!(unsafe { *p.pointer().as_ptr() }, 10); |
| |
| p.set_tag(3); |
| assert_eq!(p.tag(), 3); |
| assert_eq!(unsafe { *p.pointer().as_ptr() }, 10); |
| |
| unsafe { drop(Box::from_raw(p.pointer().as_ptr())) }; |
| |
| /// A non-null pointer type which carries several bits of metadata and maintains provenance. |
| #[repr(transparent)] |
| pub struct TaggedPointer<T>(NonNull<T>); |
| |
| impl<T> Clone for TaggedPointer<T> { |
| fn clone(&self) -> Self { |
| Self(self.0) |
| } |
| } |
| |
| impl<T> Copy for TaggedPointer<T> {} |
| |
| impl<T> TaggedPointer<T> { |
| /// The ABI-required minimum alignment of the `P` type. |
| pub const ALIGNMENT: usize = align_of::<T>(); |
| /// A mask for data-carrying bits of the address. |
| pub const DATA_MASK: usize = !Self::ADDRESS_MASK; |
| /// Number of available bits of storage in the address. |
| pub const NUM_BITS: u32 = Self::ALIGNMENT.trailing_zeros(); |
| /// A mask for the non-data-carrying bits of the address. |
| pub const ADDRESS_MASK: usize = usize::MAX << Self::NUM_BITS; |
| |
| /// Creates a new tagged pointer from a possibly null pointer. |
| pub fn new(pointer: *mut T) -> Option<TaggedPointer<T>> { |
| Some(TaggedPointer(NonNull::new(pointer)?)) |
| } |
| |
| /// Consume this tagged pointer and produce a raw mutable pointer to the |
| /// memory location. |
| pub fn pointer(self) -> NonNull<T> { |
| // SAFETY: The `addr` guaranteed to have bits set in the Self::ADDRESS_MASK, so the result will be non-null. |
| self.0 |
| .map_addr(|addr| unsafe { NonZero::new_unchecked(addr.get() & Self::ADDRESS_MASK) }) |
| } |
| |
| /// Consume this tagged pointer and produce the data it carries. |
| pub fn tag(&self) -> usize { |
| self.0.addr().get() & Self::DATA_MASK |
| } |
| |
| /// Update the data this tagged pointer carries to a new value. |
| pub fn set_tag(&mut self, data: usize) { |
| assert_eq!( |
| data & Self::ADDRESS_MASK, |
| 0, |
| "cannot set more data beyond the lowest NUM_BITS" |
| ); |
| let data = data & Self::DATA_MASK; |
| |
| // SAFETY: This value will always be non-zero because the upper bits (from |
| // ADDRESS_MASK) will always be non-zero. This a property of the type and its |
| // construction. |
| self.0 = self.0.map_addr(|addr| unsafe { |
| NonZero::new_unchecked((addr.get() & Self::ADDRESS_MASK) | data) |
| }) |
| } |
| } |
| } |
| |
| #[test] |
| fn swap_copy_untyped() { |
| // We call `{swap,copy}{,_nonoverlapping}` at `bool` type on data that is not a valid bool. |
| // These should all do untyped copies, so this should work fine. |
| let mut x = 5u8; |
| let mut y = 6u8; |
| |
| let ptr1 = addr_of_mut!(x).cast::<bool>(); |
| let ptr2 = addr_of_mut!(y).cast::<bool>(); |
| |
| unsafe { |
| ptr::swap(ptr1, ptr2); |
| ptr::swap_nonoverlapping(ptr1, ptr2, 1); |
| } |
| assert_eq!(x, 5); |
| assert_eq!(y, 6); |
| |
| unsafe { |
| ptr::copy(ptr1, ptr2, 1); |
| ptr::copy_nonoverlapping(ptr1, ptr2, 1); |
| } |
| assert_eq!(x, 5); |
| assert_eq!(y, 5); |
| } |
| |
| #[test] |
| fn test_const_copy_ptr() { |
| // `copy` and `copy_nonoverlapping` are thin layers on top of intrinsics. Ensure they correctly |
| // deal with pointers even when the pointers cross the boundary from one "element" being copied |
| // to another. |
| const { |
| let ptr1 = &1; |
| let mut ptr2 = &666; |
| |
| // Copy ptr1 to ptr2, bytewise. |
| unsafe { |
| ptr::copy( |
| &ptr1 as *const _ as *const MaybeUninit<u8>, |
| &mut ptr2 as *mut _ as *mut MaybeUninit<u8>, |
| size_of::<&i32>(), |
| ); |
| } |
| |
| // Make sure they still work. |
| assert!(*ptr1 == 1); |
| assert!(*ptr2 == 1); |
| }; |
| |
| const { |
| let ptr1 = &1; |
| let mut ptr2 = &666; |
| |
| // Copy ptr1 to ptr2, bytewise. |
| unsafe { |
| ptr::copy_nonoverlapping( |
| &ptr1 as *const _ as *const MaybeUninit<u8>, |
| &mut ptr2 as *mut _ as *mut MaybeUninit<u8>, |
| size_of::<&i32>(), |
| ); |
| } |
| |
| // Make sure they still work. |
| assert!(*ptr1 == 1); |
| assert!(*ptr2 == 1); |
| }; |
| } |
| |
| #[test] |
| fn test_const_swap_ptr() { |
| // The `swap` functions are implemented in the library, they are not primitives. |
| // Only `swap_nonoverlapping` takes a count; pointers that cross multiple elements |
| // are *not* supported. |
| // We put the pointer at an odd offset in the type and copy them as an array of bytes, |
| // which should catch most of the ways that the library implementation can get it wrong. |
| |
| #[cfg(target_pointer_width = "32")] |
| type HalfPtr = i16; |
| #[cfg(target_pointer_width = "64")] |
| type HalfPtr = i32; |
| |
| #[repr(C, packed)] |
| #[allow(unused)] |
| struct S { |
| f1: HalfPtr, |
| // Crucially this field is at an offset that is not a multiple of the pointer size. |
| ptr: &'static i32, |
| // Make sure the entire type does not have a power-of-2 size: |
| // make it 3 pointers in size. This used to hit a bug in `swap_nonoverlapping`. |
| f2: [HalfPtr; 3], |
| } |
| |
| // Ensure the entire thing is usize-aligned, so in principle this |
| // looks like it could be eligible for a `usize` copying loop. |
| #[cfg_attr(target_pointer_width = "32", repr(align(4)))] |
| #[cfg_attr(target_pointer_width = "64", repr(align(8)))] |
| struct A(S); |
| |
| const { |
| let mut s1 = A(S { ptr: &1, f1: 0, f2: [0; 3] }); |
| let mut s2 = A(S { ptr: &666, f1: 0, f2: [0; 3] }); |
| |
| // Swap ptr1 and ptr2, as an array. |
| type T = [u8; size_of::<A>()]; |
| unsafe { |
| ptr::swap(ptr::from_mut(&mut s1).cast::<T>(), ptr::from_mut(&mut s2).cast::<T>()); |
| } |
| |
| // Make sure they still work. |
| assert!(*s1.0.ptr == 666); |
| assert!(*s2.0.ptr == 1); |
| |
| // Swap them back, byte-for-byte |
| unsafe { |
| ptr::swap_nonoverlapping( |
| ptr::from_mut(&mut s1).cast::<u8>(), |
| ptr::from_mut(&mut s2).cast::<u8>(), |
| size_of::<A>(), |
| ); |
| } |
| |
| // Make sure they still work. |
| assert!(*s1.0.ptr == 1); |
| assert!(*s2.0.ptr == 666); |
| }; |
| } |
| |
| #[test] |
| fn test_null_array_as_slice() { |
| let arr: *mut [u8; 4] = null_mut(); |
| let ptr: *mut [u8] = arr.as_mut_slice(); |
| assert!(ptr.is_null()); |
| assert_eq!(ptr.len(), 4); |
| |
| let arr: *const [u8; 4] = null(); |
| let ptr: *const [u8] = arr.as_slice(); |
| assert!(ptr.is_null()); |
| assert_eq!(ptr.len(), 4); |
| } |
| |
| #[test] |
| fn test_ptr_from_raw_parts_in_const() { |
| const EMPTY_SLICE_PTR: *const [i32] = |
| std::ptr::slice_from_raw_parts(std::ptr::without_provenance(123), 456); |
| assert_eq!(EMPTY_SLICE_PTR.addr(), 123); |
| assert_eq!(EMPTY_SLICE_PTR.len(), 456); |
| } |
| |
| #[test] |
| fn test_ptr_metadata_in_const() { |
| use std::fmt::Debug; |
| |
| const ARRAY_META: () = std::ptr::metadata::<[u16; 3]>(&[1, 2, 3]); |
| const SLICE_META: usize = std::ptr::metadata::<[u16]>(&[1, 2, 3]); |
| const DYN_META: DynMetadata<dyn Debug> = std::ptr::metadata::<dyn Debug>(&[0_u8; 42]); |
| assert_eq!(ARRAY_META, ()); |
| assert_eq!(SLICE_META, 3); |
| assert_eq!(DYN_META.size_of(), 42); |
| } |
| |
| // See <https://github.com/rust-lang/rust/issues/134713> |
| const fn ptr_swap_nonoverlapping_is_untyped_inner() { |
| #[repr(C)] |
| struct HasPadding(usize, u8); |
| |
| let buf1: [usize; 2] = [1000, 2000]; |
| let buf2: [usize; 2] = [3000, 4000]; |
| |
| // HasPadding and [usize; 2] have the same size and alignment, |
| // so swap_nonoverlapping should treat them the same |
| assert!(size_of::<HasPadding>() == size_of::<[usize; 2]>()); |
| assert!(align_of::<HasPadding>() == align_of::<[usize; 2]>()); |
| |
| let mut b1 = buf1; |
| let mut b2 = buf2; |
| // Safety: b1 and b2 are distinct local variables, |
| // with the same size and alignment as HasPadding. |
| unsafe { |
| std::ptr::swap_nonoverlapping( |
| b1.as_mut_ptr().cast::<HasPadding>(), |
| b2.as_mut_ptr().cast::<HasPadding>(), |
| 1, |
| ); |
| } |
| assert!(b1[0] == buf2[0]); |
| assert!(b1[1] == buf2[1]); |
| assert!(b2[0] == buf1[0]); |
| assert!(b2[1] == buf1[1]); |
| } |
| |
| #[test] |
| fn test_ptr_swap_nonoverlapping_is_untyped() { |
| ptr_swap_nonoverlapping_is_untyped_inner(); |
| const { ptr_swap_nonoverlapping_is_untyped_inner() }; |
| } |
| |
| #[test] |
| fn test_ptr_default() { |
| #[derive(Default)] |
| struct PtrDefaultTest { |
| ptr: *const u64, |
| } |
| let default = PtrDefaultTest::default(); |
| assert!(default.ptr.is_null()); |
| |
| #[derive(Default)] |
| struct PtrMutDefaultTest { |
| ptr: *mut u64, |
| } |
| let default = PtrMutDefaultTest::default(); |
| assert!(default.ptr.is_null()); |
| } |
