One of the uses for [ambient-authority] is to mark places in the code which may be opening files or other resources in ways that may be influenced by untrusted inputs. Paths or other identifiers which are constant and known at compile time are safe. This crate provides macros for use with [cap-std] which open files and directories in a way that requires the paths to be constant and in a way that allows them to be ignored in a clippy scan for use of dynamic ambient authority.
To use, it add #![deny(clippy::disallowed_method)]
to your code and copy
[the clippy.toml file], as described [here], for example:
```rust
use openambient::openambient_file;
fn main() {
let fine = openambientfile!("Cargo.toml").unwrap();
// ... do stuff with fine
drop(fine);
let risky = std::fs::File::open("Cargo.toml").unwrap();
// ... do stuff with `risky`
drop(risky);
} ```
And run clippy configured with [these instructions]. The above code gets just one error:
error: use of a disallowed method `std::fs::File::open`
--> test.rs:10:19
|
10 | let risky = std::fs::File::open("Cargo.toml").unwrap();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
The open_ambient_file!
line does not get an error, while the
std::fs::File::open
line does.