prs_lib/util/
tty.rs

1use std::path::{Path, PathBuf};
2
3/// Maximum symlink resolving depth.
4const SYMLINK_DEPTH_MAX: u8 = 31;
5
6/// Local TTY path.
7const LOCAL_TTY_PATH: &str = "/dev/stdin";
8
9/// Get TTY path for this process.
10///
11/// Returns `None` if not in a TTY. Always returns `None` if not Linux, FreeBSD or OpenBSD.
12pub fn get_tty() -> Option<PathBuf> {
13    // None on unsupported platforms
14    if cfg!(not(any(
15        target_os = "linux",
16        target_os = "freebsd",
17        target_os = "openbsd",
18    ))) {
19        return None;
20    }
21
22    let path = PathBuf::from(LOCAL_TTY_PATH);
23    resolve_symlink(&path, 0)
24}
25
26/// Resolve symlink to the final accessible path.
27///
28/// Returns `None` if the given link could not be read (and `depth` is 0).
29///
30/// # Panics
31///
32/// Panics if a depth of `SYMLINK_DEPTH_MAX` is reached to prevent infinite loops.
33fn resolve_symlink(path: &Path, depth: u8) -> Option<PathBuf> {
34    // Panic if we're getting too deep
35    if depth >= SYMLINK_DEPTH_MAX {
36        // TODO: do not panic, return last unique path or return error
37        panic!("failed to resolve symlink because it is too deep, possible loop?");
38    }
39
40    // Read symlink path, recursively find target
41    match path.read_link() {
42        Ok(path) => resolve_symlink(&path, depth + 1),
43        Err(_) if depth == 0 => None,
44        Err(_) => Some(path.into()),
45    }
46}
prs_lib/util/tty.rs

prs_lib/util/
tty.rs
