76 lines
2.5 KiB
Rust
76 lines
2.5 KiB
Rust
use core::alloc::Layout;
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use core::mem::size_of;
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use core::ptr::{self, NonNull};
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#[test]
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fn const_unchecked_layout() {
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const SIZE: usize = 0x2000;
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const ALIGN: usize = 0x1000;
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const LAYOUT: Layout = unsafe { Layout::from_size_align_unchecked(SIZE, ALIGN) };
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const DANGLING: NonNull<u8> = LAYOUT.dangling();
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assert_eq!(LAYOUT.size(), SIZE);
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assert_eq!(LAYOUT.align(), ALIGN);
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assert_eq!(Some(DANGLING), NonNull::new(ptr::without_provenance_mut(ALIGN)));
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}
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#[test]
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fn layout_round_up_to_align_edge_cases() {
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const MAX_SIZE: usize = isize::MAX as usize;
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for shift in 0..usize::BITS {
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let align = 1_usize << shift;
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let edge = (MAX_SIZE + 1) - align;
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let low = edge.saturating_sub(10);
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let high = edge.saturating_add(10);
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assert!(Layout::from_size_align(low, align).is_ok());
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assert!(Layout::from_size_align(high, align).is_err());
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for size in low..=high {
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assert_eq!(
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Layout::from_size_align(size, align).is_ok(),
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size.next_multiple_of(align) <= MAX_SIZE,
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);
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}
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}
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}
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#[test]
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fn layout_array_edge_cases() {
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for_type::<i64>();
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for_type::<[i32; 0b10101]>();
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for_type::<[u8; 0b1010101]>();
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// Make sure ZSTs don't lead to divide-by-zero
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assert_eq!(Layout::array::<()>(usize::MAX).unwrap(), Layout::from_size_align(0, 1).unwrap());
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fn for_type<T>() {
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const MAX_SIZE: usize = isize::MAX as usize;
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let edge = (MAX_SIZE + 1) / size_of::<T>();
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let low = edge.saturating_sub(10);
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let high = edge.saturating_add(10);
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assert!(Layout::array::<T>(low).is_ok());
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assert!(Layout::array::<T>(high).is_err());
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for n in low..=high {
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assert_eq!(Layout::array::<T>(n).is_ok(), n * size_of::<T>() <= MAX_SIZE);
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}
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}
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}
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#[test]
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fn layout_debug_shows_log2_of_alignment() {
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// `Debug` is not stable, but here's what it does right now
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let layout = Layout::from_size_align(24576, 8192).unwrap();
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let s = format!("{:?}", layout);
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assert_eq!(s, "Layout { size: 24576, align: 8192 (1 << 13) }");
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}
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// Running this normally doesn't do much, but it's also run in Miri, which
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// will double-check that these are allowed by the validity invariants.
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#[test]
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fn layout_accepts_all_valid_alignments() {
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for align in 0..usize::BITS {
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let layout = Layout::from_size_align(0, 1_usize << align).unwrap();
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assert_eq!(layout.align(), 1_usize << align);
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}
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}
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