adding the possiblity to remove the filter.

fixing build too.

library/std/src/os/unix/net/datagram.rs

@@ -1,6 +1,8 @@
 #[cfg(any(doc, target_os = "android", target_os = "linux"))]
 use super::{recv_vectored_with_ancillary_from, send_vectored_with_ancillary_to, SocketAncillary};
 use super::{sockaddr_un, SocketAddr};
+#[cfg(any(doc, target_os = "netbsd", target_os = "freebsd"))]
+use crate::ffi::CStr;
 #[cfg(any(doc, target_os = "android", target_os = "linux"))]
 use crate::io::{IoSlice, IoSliceMut};
 use crate::net::Shutdown;
@@ -807,6 +809,86 @@ impl UnixDatagram {
         self.0.set_nonblocking(nonblocking)
     }
 
+    /// Moves the socket to pass unix credentials as control message in [`SocketAncillary`].
+    ///
+    /// Set the socket option `SO_PASSCRED`.
+    ///
+    /// # Examples
+    ///
+    #[cfg_attr(
+        any(
+            target_os = "android",
+            target_os = "linux",
+            target_os = "netbsd",
+            target_os = "freebsd",
+        ),
+        doc = "```no_run"
+    )]
+    #[cfg_attr(
+        not(any(
+            target_os = "android",
+            target_os = "linux",
+            target_os = "netbsd",
+            target_os = "freebsd"
+        )),
+        doc = "```ignore"
+    )]
+    /// #![feature(unix_socket_ancillary_data)]
+    /// use std::os::unix::net::UnixDatagram;
+    ///
+    /// fn main() -> std::io::Result<()> {
+    ///     let sock = UnixDatagram::unbound()?;
+    ///     sock.set_passcred(true).expect("set_passcred function failed");
+    ///     Ok(())
+    /// }
+    /// ```
+    #[cfg(any(
+        doc,
+        target_os = "android",
+        target_os = "linux",
+        target_os = "netbsd",
+        target_os = "freebsd"
+    ))]
+    #[unstable(feature = "unix_socket_ancillary_data", issue = "76915")]
+    pub fn set_passcred(&self, passcred: bool) -> io::Result<()> {
+        self.0.set_passcred(passcred)
+    }
+
+    /// Get the current value of the socket for passing unix credentials in [`SocketAncillary`].
+    /// This value can be change by [`set_passcred`].
+    ///
+    /// Get the socket option `SO_PASSCRED`.
+    ///
+    /// [`set_passcred`]: UnixDatagram::set_passcred
+    #[cfg(any(
+        doc,
+        target_os = "android",
+        target_os = "linux",
+        target_os = "netbsd",
+        target_os = "freebsd"
+    ))]
+    #[unstable(feature = "unix_socket_ancillary_data", issue = "76915")]
+    pub fn passcred(&self) -> io::Result<bool> {
+        self.0.passcred()
+    }
+
+    /// Set a filter name on the socket to filter incoming connections to defer it before accept(2)
+    ///
+    /// an empty name allows to remove this connection's filter
+    #[cfg(any(doc, target_os = "netbsd", target_os = "freebsd"))]
+    #[unstable(feature = "acceptfilter", issue = "none")]
+    pub fn set_acceptfilter(&self, name: &CStr) -> io::Result<()> {
+        self.0.set_acceptfilter(name)
+    }
+
+    /// Get a filter name if one had been set previously on the socket.
+    ///
+    #[cfg(any(doc, target_os = "netbsd", target_os = "freebsd"))]
+    #[unstable(feature = "acceptfilter", issue = "none")]
+    pub fn acceptfilter(&self) -> io::Result<&CStr> {
+        self.0.acceptfilter()
+    }
+
     /// Set the id of the socket for network filtering purpose
     ///
     #[cfg_attr(

library/std/src/os/unix/net/stream.rs

@@ -14,6 +14,7 @@ use super::{peer_cred, UCred};
 #[cfg(any(doc, target_os = "android", target_os = "linux"))]
 use super::{recv_vectored_with_ancillary_from, send_vectored_with_ancillary_to, SocketAncillary};
 use super::{sockaddr_un, SocketAddr};
+#[cfg(any(doc, target_os = "netbsd", target_os = "freebsd"))]
 use crate::ffi::CStr;
 use crate::fmt;
 use crate::io::{self, IoSlice, IoSliceMut};
@@ -450,6 +451,7 @@ impl UnixStream {
 
     /// Set a filter name on the socket to filter incoming connections to defer it before accept(2)
     ///
+    /// an empty name allows to remove this connection's filter
     #[cfg(any(doc, target_os = "netbsd", target_os = "freebsd"))]
     #[unstable(feature = "acceptfilter", issue = "none")]
     pub fn set_acceptfilter(&self, name: &CStr) -> io::Result<()> {

library/std/src/sys/pal/unix/net.rs

@@ -455,14 +455,23 @@ impl Socket {
 
     #[cfg(any(target_os = "freebsd", target_os = "netbsd"))]
     pub fn set_acceptfilter(&self, name: &CStr) -> io::Result<()> {
-        const AF_NAME_MAX: usize = 16;
-        let mut buf = [0; AF_NAME_MAX];
-        for (src, dst) in name.to_bytes().iter().zip(&mut buf[..AF_NAME_MAX - 1]) {
-            *dst = *src as i8;
+        if !name.to_bytes().is_empty() {
+            const AF_NAME_MAX: usize = 16;
+            let mut buf = [0; AF_NAME_MAX];
+            for (src, dst) in name.to_bytes().iter().zip(&mut buf[..AF_NAME_MAX - 1]) {
+                *dst = *src as i8;
+            }
+            let mut arg: libc::accept_filter_arg = unsafe { mem::zeroed() };
+            arg.af_name = buf;
+            setsockopt(self, libc::SOL_SOCKET, libc::SO_ACCEPTFILTER, &mut arg)
+        } else {
+            setsockopt(
+                self,
+                libc::SOL_SOCKET,
+                libc::SO_ACCEPTFILTER,
+                core::ptr::null_mut() as *mut c_void,
+            )
         }
-        let mut arg: libc::accept_filter_arg = unsafe { mem::zeroed() };
-        arg.af_name = buf;
-        setsockopt(self, libc::SOL_SOCKET, libc::SO_ACCEPTFILTER, &mut arg)
     }
 
     #[cfg(any(target_os = "freebsd", target_os = "netbsd"))]