fcntl add F_GETPATH support for apple/netbsd/dragonfly (#2142)

* fcntl add F_GETPATH support for apple/netbsd

* changes from review

* CHANGELOG entry

---------

Co-authored-by: SteveLauC <stevelauc@outlook.com>

Author: devnexen

CHANGELOG.md

@@ -49,6 +49,9 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 - Added `Icmp` and `IcmpV6` to `SockProtocol`.
   (#[2103](https://github.com/nix-rust/nix/pull/2103))
 
+- Added `F_GETPATH` FcntlFlags entry on Apple/NetBSD/DragonflyBSD for `::nix::fcntl`.
+  ([#2142](https://github.com/nix-rust/nix/pull/2142))
+  
 - Added `Ipv6HopLimit` to `::nix::sys::socket::ControlMessage` for Linux,
   MacOS, FreeBSD, DragonflyBSD, Android, iOS and Haiku.
   ([#2074](https://github.com/nix-rust/nix/pull/2074))

src/fcntl.rs

@@ -1,11 +1,25 @@
 use crate::errno::Errno;
 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",
+))]
+use std::ffi::CStr;
 use std::ffi::OsString;
 #[cfg(not(target_os = "redox"))]
 use std::os::raw;
 use std::os::unix::ffi::OsStringExt;
 use std::os::unix::io::RawFd;
 // For splice and copy_file_range
+#[cfg(any(
+    target_os = "netbsd",
+    target_os = "macos",
+    target_os = "ios",
+    target_os = "dragonfly",
+))]
+use std::path::PathBuf;
 #[cfg(any(
     target_os = "android",
     target_os = "freebsd",
@@ -489,6 +503,8 @@ pub enum FcntlArg<'a> {
     F_GETPIPE_SZ,
     #[cfg(any(target_os = "linux", target_os = "android"))]
     F_SETPIPE_SZ(c_int),
+    #[cfg(any(target_os = "netbsd", target_os = "dragonfly", target_os = "macos", target_os = "ios"))]
+    F_GETPATH(&'a mut PathBuf),
     // TODO: Rest of flags
 }
 
@@ -549,6 +565,15 @@ pub fn fcntl(fd: RawFd, arg: FcntlArg) -> Result<c_int> {
             F_GETPIPE_SZ => libc::fcntl(fd, libc::F_GETPIPE_SZ),
             #[cfg(any(target_os = "linux", target_os = "android"))]
             F_SETPIPE_SZ(size) => libc::fcntl(fd, libc::F_SETPIPE_SZ, size),
+            #[cfg(any(target_os = "dragonfly", target_os = "netbsd", target_os = "macos", target_os = "ios"))]
+            F_GETPATH(path) => {
+                let mut buffer = vec![0; libc::PATH_MAX as usize];
+                let res = libc::fcntl(fd, libc::F_GETPATH, buffer.as_mut_ptr());
+                let ok_res = Errno::result(res)?;
+                let optr = CStr::from_bytes_until_nul(&buffer).unwrap();
+                *path = PathBuf::from(OsString::from(optr.to_str().unwrap()));
+                return Ok(ok_res)
+            },
         }
     };
 

test/test_fcntl.rs

@@ -561,3 +561,26 @@ mod test_posix_fallocate {
         }
     }
 }
+
+#[cfg(any(
+    target_os = "dragonfly",
+    target_os = "netbsd",
+    target_os = "macos",
+    target_os = "ios"
+))]
+#[test]
+fn test_f_get_path() {
+    use nix::fcntl::*;
+    use std::{os::unix::io::AsRawFd, path::PathBuf};
+
+    let tmp = NamedTempFile::new().unwrap();
+    let fd = tmp.as_raw_fd();
+    let mut path = PathBuf::new();
+    let res =
+        fcntl(fd, FcntlArg::F_GETPATH(&mut path)).expect("get path failed");
+    assert_ne!(res, -1);
+    assert_eq!(
+        path.as_path().canonicalize().unwrap(),
+        tmp.path().canonicalize().unwrap()
+    );
+}