fcntl update following up with F_GETPATH but with FreeBSD's F_KINFO flag support instead (#2152)

Author: devnexen

CHANGELOG.md

@@ -66,6 +66,9 @@ This project adheres to [Semantic Versioning](https://semver.org/).
   MacOS, FreeBSD, DragonflyBSD, Android, iOS and Haiku.
   ([#2074](https://github.com/nix-rust/nix/pull/2074))
 
+- Added `F_KINFO` FcntlFlags entry on FreeBSD for `::nix::fcntl`.
+  ([#2152](https://github.com/nix-rust/nix/pull/2152))
+
 ## [0.27.1] - 2023-08-28
 
 ### Fixed

src/fcntl.rs

@@ -1,10 +1,13 @@
 use crate::errno::Errno;
+#[cfg(all(target_os = "freebsd", target_arch = "x86_64"))]
+use core::slice;
 use libc::{self, c_int, c_uint, size_t, ssize_t};
 #[cfg(any(
     target_os = "netbsd",
     target_os = "macos",
     target_os = "ios",
     target_os = "dragonfly",
+    all(target_os = "freebsd", target_arch = "x86_64"),
 ))]
 use std::ffi::CStr;
 use std::ffi::OsString;
@@ -18,6 +21,7 @@ use std::os::unix::io::RawFd;
     target_os = "macos",
     target_os = "ios",
     target_os = "dragonfly",
+    all(target_os = "freebsd", target_arch = "x86_64"),
 ))]
 use std::path::PathBuf;
 #[cfg(any(
@@ -505,6 +509,8 @@ pub enum FcntlArg<'a> {
     F_SETPIPE_SZ(c_int),
     #[cfg(any(target_os = "netbsd", target_os = "dragonfly", target_os = "macos", target_os = "ios"))]
     F_GETPATH(&'a mut PathBuf),
+    #[cfg(all(target_os = "freebsd", target_arch = "x86_64"))]
+    F_KINFO(&'a mut PathBuf),
     // TODO: Rest of flags
 }
 
@@ -574,6 +580,18 @@ pub fn fcntl(fd: RawFd, arg: FcntlArg) -> Result<c_int> {
                 *path = PathBuf::from(OsString::from(optr.to_str().unwrap()));
                 return Ok(ok_res)
             },
+            #[cfg(all(target_os = "freebsd", target_arch = "x86_64"))]
+            F_KINFO(path) => {
+                let mut info: libc::kinfo_file = std::mem::zeroed();
+                info.kf_structsize = std::mem::size_of::<libc::kinfo_file>() as i32;
+                let res = libc::fcntl(fd, libc::F_KINFO, &mut info);
+                let ok_res = Errno::result(res)?;
+                let p = info.kf_path;
+                let u8_slice = slice::from_raw_parts(p.as_ptr().cast(), p.len());
+                let optr = CStr::from_bytes_until_nul(u8_slice).unwrap();
+                *path = PathBuf::from(OsString::from(optr.to_str().unwrap()));
+                return Ok(ok_res)
+            },
         }
     };
 

test/test_fcntl.rs

@@ -584,3 +584,22 @@ fn test_f_get_path() {
         tmp.path().canonicalize().unwrap()
     );
 }
+
+#[cfg(all(target_os = "freebsd", target_arch = "x86_64"))]
+#[test]
+fn test_f_kinfo() {
+    use nix::fcntl::*;
+    use std::{os::unix::io::AsRawFd, path::PathBuf};
+
+    let tmp = NamedTempFile::new().unwrap();
+    // With TMPDIR set with UFS, the vnode name is not entered
+    // into the name cache thus path is always empty.
+    // Therefore, we reopen the tempfile a second time for the test
+    // to pass.
+    let tmp2 = File::open(tmp.path()).unwrap();
+    let fd = tmp2.as_raw_fd();
+    let mut path = PathBuf::new();
+    let res = fcntl(fd, FcntlArg::F_KINFO(&mut path)).expect("get path failed");
+    assert_ne!(res, -1);
+    assert_eq!(path, tmp.path());
+}