passthroughfs: add unit test for inode store

Signed-off-by: Eryu Guan <eguan@linux.alibaba.com>

Author: eryugey

src/passthrough/file_handle.rs

@@ -148,6 +148,15 @@ pub struct FileHandle {
     handle: CFileHandle,
 }
 
+impl Default for FileHandle {
+    fn default() -> Self {
+        Self {
+            mnt_id: 0,
+            handle: CFileHandle::new(0),
+        }
+    }
+}
+
 extern "C" {
     fn name_to_handle_at(
         dirfd: libc::c_int,

src/passthrough/inode_store.rs

@@ -65,3 +65,134 @@ impl InodeStore {
         self.by_handle.get(handle)
     }
 }
+
+#[cfg(test)]
+mod test {
+    use super::super::*;
+    use super::*;
+
+    use std::ffi::CStr;
+    use std::os::unix::io::{AsRawFd, RawFd};
+    use std::sync::atomic::Ordering;
+    use vmm_sys_util::tempfile::TempFile;
+
+    impl PartialEq for InodeData {
+        fn eq(&self, other: &Self) -> bool {
+            if self.inode != other.inode
+                || self.altkey != other.altkey
+                || self.mode != other.mode
+                || self.refcount.load(Ordering::Relaxed) != other.refcount.load(Ordering::Relaxed)
+            {
+                return false;
+            }
+
+            match (&self.file_or_handle, &other.file_or_handle) {
+                (FileOrHandle::File(f1), FileOrHandle::File(f2)) => {
+                    f1.as_raw_fd() == f2.as_raw_fd()
+                }
+                (FileOrHandle::Handle(h1), FileOrHandle::Handle(h2)) => h1 == h2,
+                _ => false,
+            }
+        }
+    }
+
+    fn stat_fd(fd: RawFd) -> io::Result<libc::stat64> {
+        let mut st = MaybeUninit::<libc::stat64>::zeroed();
+        let null_path = unsafe { CStr::from_bytes_with_nul_unchecked(b"\0") };
+
+        // Safe because the kernel will only write data in `st` and we check the return value.
+        let res = unsafe {
+            libc::fstatat64(
+                fd,
+                null_path.as_ptr(),
+                st.as_mut_ptr(),
+                libc::AT_EMPTY_PATH | libc::AT_SYMLINK_NOFOLLOW,
+            )
+        };
+        if res >= 0 {
+            // Safe because the kernel guarantees that the struct is now fully initialized.
+            Ok(unsafe { st.assume_init() })
+        } else {
+            Err(io::Error::last_os_error())
+        }
+    }
+
+    #[test]
+    fn test_inode_store() {
+        let mut m = InodeStore::default();
+        let tmpfile1 = TempFile::new().unwrap();
+        let tmpfile2 = TempFile::new().unwrap();
+
+        let inode1: Inode = 3;
+        let inode2: Inode = 4;
+        let inode_stat1 = InodeStat {
+            stat: stat_fd(tmpfile1.as_file().as_raw_fd()).unwrap(),
+            mnt_id: 0,
+        };
+        let inode_stat2 = InodeStat {
+            stat: stat_fd(tmpfile2.as_file().as_raw_fd()).unwrap(),
+            mnt_id: 0,
+        };
+        let ids1 = InodeAltKey::ids_from_stat(&inode_stat1);
+        let ids2 = InodeAltKey::ids_from_stat(&inode_stat2);
+        let file_or_handle1 = FileOrHandle::File(tmpfile1.into_file());
+        let file_or_handle2 = FileOrHandle::File(tmpfile2.into_file());
+        let data1 = InodeData::new(
+            inode1,
+            file_or_handle1,
+            2,
+            ids1,
+            inode_stat1.get_stat().st_mode,
+        );
+        let data2 = InodeData::new(
+            inode2,
+            file_or_handle2,
+            2,
+            ids2,
+            inode_stat2.get_stat().st_mode,
+        );
+        let data1 = Arc::new(data1);
+        let data2 = Arc::new(data2);
+
+        m.insert(data1.clone());
+
+        // get not present key, expect none
+        assert!(m.get(&1).is_none());
+
+        // get just inserted value by key, by id, by handle
+        assert!(m.get_by_ids(&InodeAltKey::default()).is_none());
+        assert!(m.get_by_handle(&FileHandle::default()).is_none());
+        assert_eq!(m.get(&inode1).unwrap(), &data1);
+        assert_eq!(m.get_by_ids(&ids1).unwrap(), &data1);
+
+        // insert another value, and check again
+        m.insert(data2.clone());
+        assert!(m.get(&1).is_none());
+        assert!(m.get_by_ids(&InodeAltKey::default()).is_none());
+        assert!(m.get_by_handle(&FileHandle::default()).is_none());
+        assert_eq!(m.get(&inode1).unwrap(), &data1);
+        assert_eq!(m.get_by_ids(&ids1).unwrap(), &data1);
+        assert_eq!(m.get(&inode2).unwrap(), &data2);
+        assert_eq!(m.get_by_ids(&ids2).unwrap(), &data2);
+
+        // remove non-present key
+        assert!(m.remove(&1).is_none());
+
+        // remove present key, return its value
+        assert_eq!(m.remove(&inode1).unwrap(), data1.clone());
+        assert!(m.get(&inode1).is_none());
+        assert!(m.get_by_ids(&ids1).is_none());
+        assert_eq!(m.get(&inode2).unwrap(), &data2);
+        assert_eq!(m.get_by_ids(&ids2).unwrap(), &data2);
+
+        // clear the map
+        m.clear();
+        assert!(m.get(&1).is_none());
+        assert!(m.get_by_ids(&InodeAltKey::default()).is_none());
+        assert!(m.get_by_handle(&FileHandle::default()).is_none());
+        assert!(m.get(&inode1).is_none());
+        assert!(m.get_by_ids(&ids1).is_none());
+        assert!(m.get(&inode2).is_none());
+        assert!(m.get_by_ids(&ids2).is_none());
+    }
+}

src/passthrough/mod.rs

@@ -88,6 +88,7 @@ impl InodeAltKey {
     }
 }
 
+#[derive(Debug)]
 enum FileOrHandle {
     File(File),
     Handle(Arc<FileHandle>),
@@ -127,6 +128,7 @@ impl AsRawFd for InodeFile<'_> {
 }
 
 /// Represents an inode in `PassthroughFs`.
+#[derive(Debug)]
 pub struct InodeData {
     inode: Inode,
     // Most of these aren't actually files but ¯\_(ツ)_/¯.