Add UnixCredentials::new() to make portable use of ScmCredentials easy

src/sys/socket/mod.rs

@@ -196,6 +196,15 @@ cfg_if! {
         pub struct UnixCredentials(libc::ucred);
 
         impl UnixCredentials {
+            /// Creates a new instance with the credentials of the current process
+            pub fn new() -> Self {
+                UnixCredentials(libc::ucred {
+                    pid: crate::unistd::getpid().as_raw(),
+                    uid: crate::unistd::getuid().as_raw(),
+                    gid: crate::unistd::getgid().as_raw(),
+                })
+            }
+
             /// Returns the process identifier
             pub fn pid(&self) -> libc::pid_t {
                 self.0.pid
@@ -232,6 +241,19 @@ cfg_if! {
         pub struct UnixCredentials(libc::cmsgcred);
 
         impl UnixCredentials {
+            /// Creates a new instance with the credentials of the current process
+            pub fn new() -> Self {
+                // The kernel overwrites it when sending SCM_CREDS
+                UnixCredentials(libc::cmsgcred {
+                    cmcred_pid: 0,
+                    cmcred_uid: 0,
+                    cmcred_euid: 0,
+                    cmcred_gid: 0,
+                    cmcred_ngroups: 0,
+                    cmcred_groups: [0; libc::CMGROUP_MAX],
+                })
+            }
+
             /// Returns the process identifier
             pub fn pid(&self) -> libc::pid_t {
                 self.0.cmcred_pid

test/sys/test_socket.rs

@@ -540,28 +540,31 @@ pub fn test_sendmsg_empty_cmsgs() {
     }
 }
 
-#[cfg(any(target_os = "android", target_os = "linux"))]
+#[cfg(any(
+    target_os = "android",
+    target_os = "linux",
+    target_os = "freebsd",
+    target_os = "dragonfly",
+))]
 #[test]
 fn test_scm_credentials() {
-    use libc;
     use nix::sys::uio::IoVec;
     use nix::unistd::{close, getpid, getuid, getgid};
     use nix::sys::socket::{socketpair, sendmsg, recvmsg, setsockopt,
                            AddressFamily, SockType, SockFlag,
-                           ControlMessage, ControlMessageOwned, MsgFlags};
+                           ControlMessage, ControlMessageOwned, MsgFlags,
+                           UnixCredentials};
+    #[cfg(any(target_os = "android", target_os = "linux"))]
     use nix::sys::socket::sockopt::PassCred;
 
     let (send, recv) = socketpair(AddressFamily::Unix, SockType::Stream, None, SockFlag::empty())
         .unwrap();
+    #[cfg(any(target_os = "android", target_os = "linux"))]
     setsockopt(recv, PassCred, &true).unwrap();
 
     {
         let iov = [IoVec::from_slice(b"hello")];
-        let cred = libc::ucred {
-            pid: getpid().as_raw(),
-            uid: getuid().as_raw(),
-            gid: getgid().as_raw(),
-        }.into();
+        let cred = UnixCredentials::new();
         let cmsg = ControlMessage::ScmCredentials(&cred);
         assert_eq!(sendmsg(send, &iov, &[cmsg], MsgFlags::empty(), None).unwrap(), 5);
         close(send).unwrap();
@@ -570,7 +573,7 @@ fn test_scm_credentials() {
     {
         let mut buf = [0u8; 5];
         let iov = [IoVec::from_mut_slice(&mut buf[..])];
-        let mut cmsgspace = cmsg_space!(libc::ucred);
+        let mut cmsgspace = cmsg_space!(UnixCredentials);
         let msg = recvmsg(recv, &iov, Some(&mut cmsgspace), MsgFlags::empty()).unwrap();
         let mut received_cred = None;
 
@@ -582,7 +585,7 @@ fn test_scm_credentials() {
                 assert_eq!(cred.gid(), getgid().as_raw());
                 received_cred = Some(cred);
             } else {
-                panic!("unexpected cmsg");
+                panic!("unexpected cmsg {:?}", cmsg);
             }
         }
         received_cred.expect("no creds received");