63 lines
1.8 KiB
Rust
63 lines
1.8 KiB
Rust
// compile-flags: -Zmiri-permissive-provenance
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#![feature(strict_provenance)]
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use std::ptr;
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/// Ensure we can expose the address of a pointer that is out-of-bounds
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fn ptr_roundtrip_out_of_bounds() {
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let x: i32 = 3;
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let x_ptr = &x as *const i32;
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let x_usize = x_ptr.wrapping_offset(128).expose_addr();
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let ptr = ptr::from_exposed_addr::<i32>(x_usize).wrapping_offset(-128);
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assert_eq!(unsafe { *ptr }, 3);
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}
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/// Ensure that we can move between allocations after casting back to a ptr
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fn ptr_roundtrip_confusion() {
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let x: i32 = 0;
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let y: i32 = 1;
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let x_ptr = &x as *const i32;
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let y_ptr = &y as *const i32;
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let x_usize = x_ptr.expose_addr();
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let y_usize = y_ptr.expose_addr();
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let ptr = ptr::from_exposed_addr::<i32>(y_usize);
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let ptr = ptr.with_addr(x_usize);
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assert_eq!(unsafe { *ptr }, 0);
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}
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/// Ensure we can cast back a different integer than the one we got when exposing.
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fn ptr_roundtrip_imperfect() {
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let x: u8 = 3;
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let x_ptr = &x as *const u8;
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let x_usize = x_ptr.expose_addr() + 128;
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let ptr = ptr::from_exposed_addr::<u8>(x_usize).wrapping_offset(-128);
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assert_eq!(unsafe { *ptr }, 3);
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}
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/// Ensure that we can roundtrip through a pointer with an address of 0
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fn ptr_roundtrip_null() {
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let x = &42;
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let x_ptr = x as *const i32;
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let x_null_ptr = x_ptr.with_addr(0); // addr 0, but still the provenance of x
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let null = x_null_ptr.expose_addr();
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assert_eq!(null, 0);
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let x_null_ptr_copy = ptr::from_exposed_addr::<i32>(null); // just a roundtrip, so has provenance of x (angelically)
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let x_ptr_copy = x_null_ptr_copy.with_addr(x_ptr.addr()); // addr of x and provenance of x
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assert_eq!(unsafe { *x_ptr_copy }, 42);
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}
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fn main() {
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ptr_roundtrip_out_of_bounds();
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ptr_roundtrip_confusion();
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ptr_roundtrip_imperfect();
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ptr_roundtrip_null();
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}
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