| commit | f32bc367f4577290dbf12b4c298ded4c930a86a7 | [log] [tgz] |
|---|---|---|
| author | Victor Hsieh <[email protected]> | Tue Dec 15 13:56:41 2020 -0800 |
| committer | Victor Hsieh <[email protected]> | Wed Dec 16 09:01:35 2020 -0800 |
| tree | 0f71108f0df4dec57714cdde613b9bf02ef490bf | |
| parent | 3037f986244f7a025bc269c67f1053a808b72e30 [diff] |
Import memoffset from crates.io
This is generated with get_rust_pkg.py, plus
- src/lib.rs, src/span_of.rs
- patches/std.diff
* Since Android does not support building with no-std, disable no-std
and replace `core` with `std`.
- Android.bp
- patches/Android.bp.patch
* remove doc-comment just to avoid one dependnecy. Can be added later.
- TEST_MAPPING
Bug: 174797066
Test: mma
Test: tools/external_updater/updater.sh update --refresh --keep_date
rust/crates/memoffset
Change-Id: I836d46eb71f1f0b1449318076e0eb266adbfe4c9
C-Like offset_of functionality for Rust structs.
Introduces the following macros:
offset_of! for obtaining the offset of a member of a struct.offset_of_tuple! for obtaining the offset of a member of a tuple. (Requires Rust 1.20+)span_of! for obtaining the range that a field, or fields, span.memoffset works under no_std environments.
Add the following dependency to your Cargo.toml:
[dependencies] memoffset = "0.6"
These versions will compile fine with rustc versions greater or equal to 1.19.
Add the following lines at the top of your main.rs or lib.rs files.
#[macro_use] extern crate memoffset;
#[macro_use] extern crate memoffset; #[repr(C, packed)] struct Foo { a: u32, b: u32, c: [u8; 5], d: u32, } fn main() { assert_eq!(offset_of!(Foo, b), 4); assert_eq!(offset_of!(Foo, d), 4+4+5); assert_eq!(span_of!(Foo, a), 0..4); assert_eq!(span_of!(Foo, a .. c), 0..8); assert_eq!(span_of!(Foo, a ..= c), 0..13); assert_eq!(span_of!(Foo, ..= d), 0..17); assert_eq!(span_of!(Foo, b ..), 4..17); }
memoffset has experimental support for compile-time offset_of! on a nightly compiler.
In order to use it, you must enable the unstable_const crate feature and several compiler features.
Cargo.toml:
[dependencies.memoffset] version = "0.6" features = ["unstable_const"]
Your crate root: (lib.rs/main.rs)
#![feature(ptr_offset_from, const_ptr_offset_from, const_maybe_uninit_as_ptr, const_raw_ptr_deref)]
If you intend to use offset_of! inside a const fn, also add the const_fn compiler feature.
Recent nightlies support a way to create raw pointers that avoids creating intermediate safe references. memoffset can make use of that feature to avoid what is technically Undefined Behavior. Use the unstable_raw feature to enable this.