Rollup merge of #141990 - Qelxiros:141975-unix_send_signal, r=ChrisDenton,tgross35

Implement send_signal for unix child processes

Tracking issue: rust-lang/rust#141975

There are two main differences between my implementation and the Public API section of the tracking issue. ~First, `send_signal` requires a mutable reference, like `Child::kill`.~ Second, `ChildExt` has `Sealed` as a supertrait, bringing it more in line with other extension traits like `CommandExt`.

try-job: `dist-various*`
try-job: `test-various*`

1 files changed, 8 insertions, 4 deletions

diff --git a/library/std/src/sys/process/unix/unix.rs b/library/std/src/sys/process/unix/unix.rs
index 4f595ac9a1c..1fe80c13b81 100644
--- a/library/std/src/sys/process/unix/unix.rs
+++ b/library/std/src/sys/process/unix/unix.rs
@@ -963,9 +963,13 @@ impl Process {
         self.pid as u32
     }
 
-    pub fn kill(&mut self) -> io::Result<()> {
+    pub fn kill(&self) -> io::Result<()> {
+        self.send_signal(libc::SIGKILL)
+    }
+
+    pub(crate) fn send_signal(&self, signal: i32) -> io::Result<()> {
         // If we've already waited on this process then the pid can be recycled
-        // and used for another process, and we probably shouldn't be killing
+        // and used for another process, and we probably shouldn't be signaling
         // random processes, so return Ok because the process has exited already.
         if self.status.is_some() {
             return Ok(());
@@ -973,9 +977,9 @@ impl Process {
         #[cfg(target_os = "linux")]
         if let Some(pid_fd) = self.pidfd.as_ref() {
             // pidfd_send_signal predates pidfd_open. so if we were able to get an fd then sending signals will work too
-            return pid_fd.kill();
+            return pid_fd.send_signal(signal);
         }
-        cvt(unsafe { libc::kill(self.pid, libc::SIGKILL) }).map(drop)
+        cvt(unsafe { libc::kill(self.pid, signal) }).map(drop)
     }
 
     pub fn wait(&mut self) -> io::Result<ExitStatus> {