uucore: add linux function to manage safe traversal (openat, unlinkat, etc)

src/uucore/Cargo.toml

@@ -137,6 +137,7 @@ proc-info = ["tty", "walkdir"]
 quoting-style = ["i18n-common"]
 ranges = []
 ringbuffer = []
+safe-traversal = ["libc"]
 selinux = ["dep:selinux"]
 signals = []
 sum = [

src/uucore/src/lib/features.rs

@@ -65,6 +65,8 @@ pub mod pipes;
 pub mod proc_info;
 #[cfg(all(unix, feature = "process"))]
 pub mod process;
+#[cfg(all(target_os = "linux", feature = "safe-traversal"))]
+pub mod safe_traversal;
 #[cfg(all(target_os = "linux", feature = "tty"))]
 pub mod tty;
 

src/uucore/src/lib/lib.rs

@@ -90,6 +90,8 @@ pub use crate::features::perms;
 pub use crate::features::pipes;
 #[cfg(all(unix, feature = "process"))]
 pub use crate::features::process;
+#[cfg(all(target_os = "linux", feature = "safe-traversal"))]
+pub use crate::features::safe_traversal;
 #[cfg(all(unix, not(target_os = "fuchsia"), feature = "signals"))]
 pub use crate::features::signals;
 #[cfg(all(