From 601ea3ef1918feb1bb69687a6b43c091cc9f4e13 Mon Sep 17 00:00:00 2001
From: Jan Verbeek <jan.verbeek@posteo.nl>
Date: Fri, 27 Aug 2021 16:16:59 +0200
Subject: [PATCH] uucore::process: Add a few notes

---
 src/uucore/src/lib/features/process.rs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/uucore/src/lib/features/process.rs b/src/uucore/src/lib/features/process.rs
index fc4b7ed48..d0f530a5a 100644
--- a/src/uucore/src/lib/features/process.rs
+++ b/src/uucore/src/lib/features/process.rs
@@ -19,6 +19,8 @@ use std::process::ExitStatus as StdExitStatus;
 use std::thread;
 use std::time::{Duration, Instant};
 
+// SAFETY: These functions always succeed and return simple integers.
+
 /// `geteuid()` returns the effective user ID of the calling process.
 pub fn geteuid() -> uid_t {
     unsafe { libc::geteuid() }
@@ -96,6 +98,9 @@ impl fmt::Display for ExitStatus {
 /// Missing methods for Child objects
 pub trait ChildExt {
     /// Send a signal to a Child process.
+    ///
+    /// Caller beware: if the process already exited then you may accidentally
+    /// send the signal to an unrelated process that recycled the PID.
     fn send_signal(&mut self, signal: usize) -> io::Result<()>;
 
     /// Wait for a process to finish or return after the specified duration.