Show file name and access mode in Debug instance for File on OS X

src/liblibc/lib.rs

@@ -4978,6 +4978,8 @@ pub mod posix01 {
             pub const F_GETFL : c_int = 3;
             pub const F_SETFL : c_int = 4;
 
+            pub const O_ACCMODE : c_int = 3;
+
             pub const SIGTRAP : c_int = 5;
             pub const SIG_IGN: size_t = 1;
 
@@ -5130,6 +5132,7 @@ pub mod extra {
             pub const O_DSYNC : c_int = 4194304;
             pub const O_SYNC : c_int = 128;
             pub const O_NONBLOCK : c_int = 4;
+            pub const F_GETPATH : c_int = 50;
             pub const F_FULLFSYNC : c_int = 51;
 
             pub const MAP_COPY : c_int = 0x0002;
@@ -5151,6 +5154,8 @@ pub mod extra {
             pub const SO_DONTTRUNC: c_int = 0x2000;
             pub const SO_WANTMORE: c_int = 0x4000;
             pub const SO_WANTOOBFLAG: c_int = 0x8000;
+
+            pub const PATH_MAX: c_int = 1024;
         }
         pub mod sysconf {
             use types::os::arch::c95::c_int;

src/libstd/sys/unix/fs.rs

@@ -370,13 +370,25 @@ fn get_path(fd: c_int) -> Option<PathBuf> {
             readlink(&p).ok()
         }
 
-        #[cfg(not(target_os = "linux"))]
+        #[cfg(target_os = "macos")]
+        fn get_path(fd: c_int) -> Option<PathBuf> {
+            let mut buf = vec![0;libc::PATH_MAX as usize];
+            let n = unsafe { libc::fcntl(fd, libc::F_GETPATH, buf.as_ptr()) };
+            if n == -1 {
+                return None;
+            }
+            let l = buf.iter().position(|&c| c == 0).unwrap();
+            buf.truncate(l as usize);
+            Some(PathBuf::from(OsString::from_vec(buf)))
+        }
+
+        #[cfg(not(any(target_os = "linux", target_os = "macos")))]
         fn get_path(_fd: c_int) -> Option<PathBuf> {
             // FIXME(#24570): implement this for other Unix platforms
             None
         }
 
-        #[cfg(target_os = "linux")]
+        #[cfg(any(target_os = "linux", target_os = "macos"))]
         fn get_mode(fd: c_int) -> Option<(bool, bool)> {
             let mode = unsafe { libc::fcntl(fd, libc::F_GETFL) };
             if mode == -1 {
@@ -390,7 +402,7 @@ fn get_mode(fd: c_int) -> Option<(bool, bool)> {
             }
         }
 
-        #[cfg(not(target_os = "linux"))]
+        #[cfg(not(any(target_os = "linux", target_os = "macos")))]
         fn get_mode(_fd: c_int) -> Option<(bool, bool)> {
             // FIXME(#24570): implement this for other Unix platforms
             None