mirror of
https://github.com/uutils/coreutils
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87 lines
2.6 KiB
Markdown
87 lines
2.6 KiB
Markdown
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# Conventions
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In order to achieve our goal of wrapping [libc][libc] code in idiomatic rust
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constructs with minimal performance overhead, we follow the following
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conventions.
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Note that, thus far, not all the code follows these conventions and not all
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conventions we try to follow have been documented here. If you find an instance
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of either, feel free to remedy the flaw by opening a pull request with
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appropriate changes or additions.
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## Change Log
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We follow the conventions laid out in [Keep A CHANGELOG][kacl].
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[kacl]: https://github.com/olivierlacan/keep-a-changelog/tree/18adb5f5be7a898d046f6a4acb93e39dcf40c4ad
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## libc constants, functions and structs
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We do not define integer constants ourselves, but use or reexport them from the
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[libc crate][libc].
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We use the functions exported from [libc][libc] instead of writing our own
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`extern` declarations.
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We use the `struct` definitions from [libc][libc] internally instead of writing
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our own. If we want to add methods to a libc type, we use the newtype pattern.
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For example,
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```rust
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pub struct SigSet(libc::sigset_t);
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impl SigSet {
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...
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}
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```
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When creating newtypes, we use Rust's `CamelCase` type naming convention.
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## Bitflags
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Many C functions have flags parameters that are combined from constants using
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bitwise operations. We represent the types of these parameters by types defined
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using our `libc_bitflags!` macro, which is a convenience wrapper around the
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`bitflags!` macro from the [bitflags crate][bitflags] that brings in the
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constant value from `libc`.
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We name the type for a set of constants whose element's names start with `FOO_`
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`FooFlags`.
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For example,
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```rust
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libc_bitflags!{
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pub struct ProtFlags: libc::c_int {
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PROT_NONE;
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PROT_READ;
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PROT_WRITE;
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PROT_EXEC;
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#[cfg(any(target_os = "linux", target_os = "android"))]
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PROT_GROWSDOWN;
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#[cfg(any(target_os = "linux", target_os = "android"))]
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PROT_GROWSUP;
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}
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}
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```
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## Enumerations
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We represent sets of constants that are intended as mutually exclusive arguments
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to parameters of functions by [enumerations][enum].
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## Structures Initialized by libc Functions
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Whenever we need to use a [libc][libc] function to properly initialize a
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variable and said function allows us to use uninitialized memory, we use
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[`std::mem::MaybeUninit`][std_MaybeUninit] when defining the variable. This
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allows us to avoid the overhead incurred by zeroing or otherwise initializing
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the variable.
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[bitflags]: https://crates.io/crates/bitflags/
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[enum]: https://doc.rust-lang.org/reference.html#enumerations
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[libc]: https://crates.io/crates/libc/
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[std_MaybeUninit]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html
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