https://github.com/sunfishcode/c-ward

An implementation of libc written in Rust
https://github.com/sunfishcode/c-ward

libc rust

Last synced: 27 days ago
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An implementation of libc written in Rust

• Host: GitHub
• URL: https://github.com/sunfishcode/c-ward
• Owner: sunfishcode
• License: other
• Created: 2023-09-11T15:20:14.000Z (about 1 year ago)
• Default Branch: main
• Last Pushed: 2024-10-13T16:28:46.000Z (about 1 month ago)
• Last Synced: 2024-10-13T17:11:22.564Z (about 1 month ago)
• Topics: libc, rust
• Language: Rust
• Homepage:
• Size: 592 KB
• Stars: 192
• Watchers: 9
• Forks: 11
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • License: LICENSE-APACHE
  • Code of conduct: CODE_OF_CONDUCT.md

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README

        


  
c-ward


  


    An implementation of libc written in Rust

  


  


    

    

    

    

    

    

  



c-ward is an implementation of the libc ABI written in Rust.

It consists of two crates:

 - [c-scape], which is `no_std`, and

 - [c-gull], which pulls in c-scape and additionally provides features

   using `std`.

It is a goal of c-ward to be a C ABI layer on top of Rust-idomatic libraries,

rather than to have significant implementation code of its own.

In theory c-ward could be extended to be ABI-compatible with different

platforms, however currently it is only known to be ABI-compatible with

\*-unknown-linux-gnu\* platforms.

The primary way this is used is through [Mustang] and [Eyra], as their libc

implementations. It can also be used as a regular library in

["coexist-with-libc" mode].

## Runtime requirements

Resolving users and DNS records requires the execution of `getent` which

prints the entries on stdout. On a regular glibc system the `getent`

binary is provided by it and uses the NSS setup as usual.

Similar, a musl system also provides `getent` (but does not use NSS).

## Similar crates

Another libc implementation is [relibc]. [tinyrlibc] is a very minimal set of

libc functions for bare-metal embedded platforms.

## Where's the `#![no_builtins]`?

Normally, a libc implementation would use `#[no_builtins]` to prevent compilers

from noticing the bodies of libc functions implement the semantics of libc

functions and replacing them with calls, which effectively makes them uselessly

recursive calls to themselves.

However, `#[no_builtins]` is too pessimistic, because we don't need to disable

all pattern matching, just these specific cases.

So instead, c-scape and c-gull are just careful to avoid open-coding functions

which are known to get pattern-matched into builtins.

[c-scape]: https://github.com/sunfishcode/c-ward/tree/main/c-scape#readme

[c-gull]: https://github.com/sunfishcode/c-ward/tree/main/c-gull#readme

[relibc]: https://gitlab.redox-os.org/redox-os/relibc/

[tinyrlibc]: https://github.com/rust-embedded-community/tinyrlibc

[Mustang]: https://github.com/sunfishcode/mustang#readme

[Eyra]: https://github.com/sunfishcode/eyra#readme

["coexist-with-libc" mode]: https://github.com/sunfishcode/c-ward/blob/main/example-crates/libc-replacement#readme