feat: impl AsFd for PtyMaster (#2355)

Fixes #2354

Author: yshui

changelog/2355.added.md

@@ -0,0 +1 @@
+Added `impl AsFd for pty::PtyMaster`

src/pty.rs

@@ -58,6 +58,12 @@ impl AsRawFd for PtyMaster {
     }
 }
 
+impl AsFd for PtyMaster {
+    fn as_fd(&self) -> BorrowedFd<'_> {
+        self.0.as_fd()
+    }
+}
+
 impl IntoRawFd for PtyMaster {
     fn into_raw_fd(self) -> RawFd {
         let fd = self.0;

test/test_pty.rs

@@ -17,9 +17,10 @@ use nix::unistd::{pause, write};
 fn test_ptsname_equivalence() {
     let _m = crate::PTSNAME_MTX.lock();
 
-    // Open a new PTTY master
+    // Open a new PTY master
     let master_fd = posix_openpt(OFlag::O_RDWR).unwrap();
     assert!(master_fd.as_raw_fd() > 0);
+    assert!(master_fd.as_fd().as_raw_fd() == master_fd.as_raw_fd());
 
     // Get the name of the slave
     let slave_name = unsafe { ptsname(&master_fd) }.unwrap();