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, 5 insertions, 1 deletions

diff --git a/library/std/src/sys/pal/unix/linux/pidfd.rs b/library/std/src/sys/pal/unix/linux/pidfd.rs
index 2d949ec9e91..47e9a616bfd 100644
--- a/library/std/src/sys/pal/unix/linux/pidfd.rs
+++ b/library/std/src/sys/pal/unix/linux/pidfd.rs
@@ -13,11 +13,15 @@ pub(crate) struct PidFd(FileDesc);
 
 impl PidFd {
     pub fn kill(&self) -> io::Result<()> {
+        self.send_signal(libc::SIGKILL)
+    }
+
+    pub(crate) fn send_signal(&self, signal: i32) -> io::Result<()> {
         cvt(unsafe {
             libc::syscall(
                 libc::SYS_pidfd_send_signal,
                 self.0.as_raw_fd(),
-                libc::SIGKILL,
+                signal,
                 crate::ptr::null::<()>(),
                 0,
             )