Rollup merge of #79600 - nicokoch:kernel_copy_unixstream, r=m-ou-se

std::io: Use sendfile for UnixStream

`UnixStream` was forgotten in #75272 .

Benchmark yields the following results.
Before:
`running 1 test
test sys::unix::kernel_copy::tests::bench_file_to_uds_copy        ... bench:      54,399 ns/iter (+/- 6,817) = 2409 MB/s`

After:
`running 1 test
test sys::unix::kernel_copy::tests::bench_file_to_uds_copy        ... bench:      18,627 ns/iter (+/- 6,007) = 7036 MB/s`

1 files changed, 29 insertions, 0 deletions

diff --git a/library/std/src/sys/unix/kernel_copy.rs b/library/std/src/sys/unix/kernel_copy.rs
index 1dc16ef0993..f08c828ecff 100644
--- a/library/std/src/sys/unix/kernel_copy.rs
+++ b/library/std/src/sys/unix/kernel_copy.rs
@@ -56,6 +56,7 @@ use crate::mem::ManuallyDrop;
 use crate::net::TcpStream;
 use crate::os::unix::fs::FileTypeExt;
 use crate::os::unix::io::{AsRawFd, FromRawFd, RawFd};
+use crate::os::unix::net::UnixStream;
 use crate::process::{ChildStderr, ChildStdin, ChildStdout};
 use crate::ptr;
 use crate::sync::atomic::{AtomicBool, Ordering};
@@ -320,6 +321,34 @@ impl CopyWrite for &TcpStream {
     }
 }
 
+impl CopyRead for UnixStream {
+    fn properties(&self) -> CopyParams {
+        // avoid the stat syscall since we can be fairly sure it's a socket
+        CopyParams(FdMeta::Socket, Some(self.as_raw_fd()))
+    }
+}
+
+impl CopyRead for &UnixStream {
+    fn properties(&self) -> CopyParams {
+        // avoid the stat syscall since we can be fairly sure it's a socket
+        CopyParams(FdMeta::Socket, Some(self.as_raw_fd()))
+    }
+}
+
+impl CopyWrite for UnixStream {
+    fn properties(&self) -> CopyParams {
+        // avoid the stat syscall since we can be fairly sure it's a socket
+        CopyParams(FdMeta::Socket, Some(self.as_raw_fd()))
+    }
+}
+
+impl CopyWrite for &UnixStream {
+    fn properties(&self) -> CopyParams {
+        // avoid the stat syscall since we can be fairly sure it's a socket
+        CopyParams(FdMeta::Socket, Some(self.as_raw_fd()))
+    }
+}
+
 impl CopyWrite for ChildStdin {
     fn properties(&self) -> CopyParams {
         CopyParams(FdMeta::Pipe, Some(self.as_raw_fd()))