Merge #1664

1664: also implement Read and Write for &PtyMaster r=rtzoeller a=doy

align with std::fs::File which also does this because the underlying calls are just syscalls which are safe to run concurrently

Co-authored-by: Jesse Luehrs <doy@tozt.net>

3 files changed, 27 insertions, 0 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d85b42d0..65681677 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -52,6 +52,8 @@ This project adheres to [Semantic Versioning](https://semver.org/).
   (#[1553](https://github.com/nix-rust/nix/pull/1553))
 - Added `ENOTRECOVERABLE` and `EOWNERDEAD` error codes on DragonFly.
   (#[1665](https://github.com/nix-rust/nix/pull/1665))
+- Implemented `Read` and `Write` for `&PtyMaster`
+  (#[1664](https://github.com/nix-rust/nix/pull/1664))
 
 ### Changed
 
diff --git a/src/pty.rs b/src/pty.rs
index ae304d83..bb266a65 100644
--- a/src/pty.rs
+++ b/src/pty.rs
@@ -95,6 +95,21 @@ impl io::Write for PtyMaster {
     }
 }
 
+impl io::Read for &PtyMaster {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        unistd::read(self.0, buf).map_err(io::Error::from)
+    }
+}
+
+impl io::Write for &PtyMaster {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        unistd::write(self.0, buf).map_err(io::Error::from)
+    }
+    fn flush(&mut self) -> io::Result<()> {
+        Ok(())
+    }
+}
+
 /// Grant access to a slave pseudoterminal (see
 /// [`grantpt(3)`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/grantpt.html))
 ///
diff --git a/test/test_pty.rs b/test/test_pty.rs
index 71932f2d..1a7cab81 100644
--- a/test/test_pty.rs
+++ b/test/test_pty.rs
@@ -170,6 +170,11 @@ fn test_read_ptty_pair() {
     slave.write_all(b"hello").unwrap();
     master.read_exact(&mut buf).unwrap();
     assert_eq!(&buf, b"hello");
+
+    let mut master = &master;
+    slave.write_all(b"hello").unwrap();
+    master.read_exact(&mut buf).unwrap();
+    assert_eq!(&buf, b"hello");
 }
 
 /// Test `io::Write` on the PTTY master
@@ -182,6 +187,11 @@ fn test_write_ptty_pair() {
     master.write_all(b"adios").unwrap();
     slave.read_exact(&mut buf).unwrap();
     assert_eq!(&buf, b"adios");
+
+    let mut master = &master;
+    master.write_all(b"adios").unwrap();
+    slave.read_exact(&mut buf).unwrap();
+    assert_eq!(&buf, b"adios");
 }
 
 #[test]