fcntl adding F_LOG2PHYS* flags. (nix-rust#2483)

to get the current device address, in practice its current offset only.

changelog/2483.added.md

@@ -0,0 +1 @@
+Add `F_LOG2PHYS` and `F_LOG2PHYS_EXT` for Apple target

src/fcntl.rs

@@ -808,6 +808,17 @@ pub enum FcntlArg<'a> {
     /// fstore_t field fst_bytesalloc.
     #[cfg(apple_targets)]
     F_PREALLOCATE(&'a mut libc::fstore_t),
+    #[cfg(apple_targets)]
+    /// Get disk device information. In practice,
+    /// only the file offset data is set.
+    F_LOG2PHYS(&'a mut libc::off_t),
+    #[cfg(apple_targets)]
+    /// Get disk device information. In practice,
+    /// only the file offset data is set.
+    /// The difference with F_LOG2PHYS is the struct passed
+    /// is used as both IN/OUT as both its l2p_devoffset and
+    /// l2p_contigbytes can be used for more specific queries.
+    F_LOG2PHYS_EXT(&'a mut libc::log2phys),
     // TODO: Rest of flags
 }
 
@@ -919,6 +930,18 @@ pub fn fcntl<Fd: std::os::fd::AsFd>(fd: Fd, arg: FcntlArg) -> Result<c_int> {
             #[cfg(apple_targets)]
             F_RDADVISE(rad) => {
                 libc::fcntl(fd, libc::F_RDADVISE, &rad)
+            },
+            #[cfg(apple_targets)]
+            F_LOG2PHYS(offset) => {
+                let mut info: libc::log2phys = std::mem::zeroed();
+                let res = libc::fcntl(fd, libc::F_LOG2PHYS, &mut info);
+                let ok_res = Errno::result(res)?;
+                *offset = info.l2p_devoffset;
+                return Ok(ok_res)
+            }
+            #[cfg(apple_targets)]
+            F_LOG2PHYS_EXT(info) => {
+                libc::fcntl(fd, libc::F_LOG2PHYS_EXT, info)
             }
             #[cfg(apple_targets)]
             F_RDAHEAD(on) => {

test/test_fcntl.rs

@@ -770,3 +770,25 @@ fn test_f_rdadvise() {
     assert_eq!(contents.len(), read(&fd, &mut buf).unwrap());
     assert_eq!(contents, &buf[0..contents.len()]);
 }
+
+#[cfg(apple_targets)]
+#[test]
+fn test_f_log2phys() {
+    use nix::fcntl::*;
+
+    const CONTENTS: &[u8] = b"abcd";
+    let mut tmp = NamedTempFile::new().unwrap();
+    tmp.write_all(CONTENTS).unwrap();
+    let mut offset: libc::off_t = 0;
+    let mut res = fcntl(&tmp, FcntlArg::F_LOG2PHYS(&mut offset))
+        .expect("log2phys failed");
+    assert_ne!(res, -1);
+    assert_ne!(offset, 0);
+    let mut info: libc::log2phys = unsafe { std::mem::zeroed() };
+    info.l2p_contigbytes = CONTENTS.len() as _;
+    info.l2p_devoffset = 3;
+    res = fcntl(&tmp, FcntlArg::F_LOG2PHYS_EXT(&mut info))
+        .expect("log2phys failed");
+    assert_ne!(res, -1);
+    assert_ne!({ info.l2p_devoffset }, 3);
+}