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<div align="center">
<h1><code>cap-std</code></h1>
<p>
<strong>Capability-based version of the Rust standard library</strong>
</p>
<p>
<a href="https://github.com/bytecodealliance/cap-std/actions?query=workflow%3ACI"><img src="https://github.com/bytecodealliance/cap-std/workflows/CI/badge.svg" alt="Github Actions CI Status" /></a>
<a href="https://crates.io/crates/cap-std"><img src="https://img.shields.io/crates/v/cap-std.svg" alt="crates.io page" /></a>
<a href="https://docs.rs/cap-std"><img src="https://docs.rs/cap-std/badge.svg" alt="docs.rs docs" /></a>
</p>
</div>
This crate provides a capability-based version of [`std`], providing
sandboxed filesystem, networking, and clock APIs. See the [toplevel README.md]
for more information about sandboxing using capability-based security.
The filesystem module [`cap_std::fs`], the networking module [`cap_std::net`],
and the time module [`cap_std::time`] currently support Linux, macOS, FreeBSD,
and Windows. WASI support is in development, though not yet usable.
Example usage of [`Dir`] for filesystem access:
```rust
use std::io;
use cap_std::fs::Dir;
/// Open files relative to `dir`.
fn dir_example(dir: &Dir) -> io::Result<()> {
// This works (assuming symlinks don't lead outside of `dir`).
let file = dir.open("the/thing.txt")?;
// This fails, since `..` leads outside of `dir`.
let hidden = dir.open("../hidden.txt")?;
// This fails, as creating symlinks to absolute paths is not permitted.
dir.symlink("/hidden.txt", "misdirection.txt")?;
// However, even if the symlink had succeeded, or, if there is a
// pre-existing symlink to an absolute directory, following a
// symlink which would lead outside the sandbox also fails.
let secret = dir.open("misdirection.txt")?;
Ok(())
}
```
Example usage of [`Pool`] for network access:
```rust
use std::io;
use cap_std::net::Pool;
/// Open network addresses within `pool`.
fn pool_example(pool: &Pool) -> io::Result<()> {
// Connect to an address. This succeeds only if the given address and
// port are present in `pool`.
let stream = pool.connect_tcp_stream("localhost:3333")?;
Ok(())
}
```
[`std`]: https://doc.rust-lang.org/std/
[toplevel README.md]: https://github.com/bytecodealliance/cap-std/blob/main/README.md
[`cap_std::fs`]: https://docs.rs/cap-std/latest/cap_std/fs/index.html
[`cap_std::net`]: https://docs.rs/cap-std/latest/cap_std/net/index.html
[`cap_std::time`]: https://docs.rs/cap-std/latest/cap_std/time/index.html
[`Pool`]: https://docs.rs/cap-std/latest/cap_std/net/struct.Pool.html
[`Dir`]: https://docs.rs/cap-std/latest/cap_std/fs/struct.Dir.html
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