Support unlink and rmdir
The change implements the regular unlink and rmdir logic like other
filesystems. That is, assuming permission,
- A file can always be removed from a directory.
- A directory can only be removed from the parent directory if it
contains no entries.
- Even after a file is deleted from the directory, one can still read
and/or write through the existing FDs. The filesystem will delete the
actual entry when there is no active FDs.
The change focuses to ensure the integrity of AuthFS as always. AuthFS
should manage FD lifetime correctly by itself.
On the contrary, AuthFS does not currently close remote FDs even if it
should better to.
Bug: 208892249
Test: atest AuthFsHostTest ComposHostTestCases
Change-Id: Iab565e85bd7111bdfe423293c271d69ced4db2ea
diff --git a/authfs/src/file/dir.rs b/authfs/src/file/dir.rs
index 2eaaddd..2a8f359 100644
--- a/authfs/src/file/dir.rs
+++ b/authfs/src/file/dir.rs
@@ -14,6 +14,7 @@
* limitations under the License.
*/
+use log::warn;
use std::collections::{hash_map, HashMap};
use std::io;
use std::path::{Path, PathBuf};
@@ -25,6 +26,16 @@
const MAX_ENTRIES: u16 = 100; // Arbitrary limit
+struct DirEntry {
+ inode: Inode,
+
+ // This information is duplicated since it is also available in `AuthFs::inode_table` via the
+ // type system. But it makes it simple to deal with deletion, where otherwise we need to get a
+ // mutable parent directory in the table, and query the table for directory/file type checking
+ // at the same time.
+ is_dir: bool,
+}
+
/// A remote directory backed by a remote directory FD, where the provider/fd_server is not
/// trusted.
///
@@ -43,9 +54,9 @@
service: VirtFdService,
remote_dir_fd: i32,
- /// Mapping of entry names to the corresponding inode number. The actual file/directory is
- /// stored in the global pool in fusefs.
- entries: HashMap<PathBuf, Inode>,
+ /// Mapping of entry names to the corresponding inode. The actual file/directory is stored in
+ /// the global pool in fusefs.
+ entries: HashMap<PathBuf, DirEntry>,
}
impl RemoteDirEditor {
@@ -75,7 +86,7 @@
let new_remote_file =
VerifiedFileEditor::new(RemoteFileEditor::new(self.service.clone(), new_fd));
- self.entries.insert(basename.to_path_buf(), inode);
+ self.entries.insert(basename.to_path_buf(), DirEntry { inode, is_dir: false });
Ok(new_remote_file)
}
@@ -92,14 +103,68 @@
.map_err(into_io_error)?;
let new_remote_dir = RemoteDirEditor::new(self.service.clone(), new_fd);
- self.entries.insert(basename.to_path_buf(), inode);
+ self.entries.insert(basename.to_path_buf(), DirEntry { inode, is_dir: true });
Ok(new_remote_dir)
}
+ /// Deletes a file
+ pub fn delete_file(&mut self, basename: &Path) -> io::Result<Inode> {
+ let inode = self.force_delete_entry(basename, /* expect_dir */ false)?;
+
+ let basename_str =
+ basename.to_str().ok_or_else(|| io::Error::from_raw_os_error(libc::EINVAL))?;
+ if let Err(e) = self.service.deleteFile(self.remote_dir_fd, basename_str) {
+ // Ignore the error to honor the local state.
+ warn!("Deletion on the host is reportedly failed: {:?}", e);
+ }
+ Ok(inode)
+ }
+
+ /// Forces to delete a directory. The caller must only call if `basename` is a directory and
+ /// empty.
+ pub fn force_delete_directory(&mut self, basename: &Path) -> io::Result<Inode> {
+ let inode = self.force_delete_entry(basename, /* expect_dir */ true)?;
+
+ let basename_str =
+ basename.to_str().ok_or_else(|| io::Error::from_raw_os_error(libc::EINVAL))?;
+ if let Err(e) = self.service.deleteDirectory(self.remote_dir_fd, basename_str) {
+ // Ignore the error to honor the local state.
+ warn!("Deletion on the host is reportedly failed: {:?}", e);
+ }
+ Ok(inode)
+ }
+
/// Returns the inode number of a file or directory named `name` previously created through
/// `RemoteDirEditor`.
- pub fn find_inode(&self, name: &Path) -> Option<Inode> {
- self.entries.get(name).copied()
+ pub fn find_inode(&self, name: &Path) -> io::Result<Inode> {
+ self.entries
+ .get(name)
+ .map(|entry| entry.inode)
+ .ok_or_else(|| io::Error::from_raw_os_error(libc::ENOENT))
+ }
+
+ /// Returns whether the directory has an entry of the given name.
+ pub fn has_entry(&self, name: &Path) -> bool {
+ self.entries.contains_key(name)
+ }
+
+ fn force_delete_entry(&mut self, basename: &Path, expect_dir: bool) -> io::Result<Inode> {
+ // Kernel should only give us a basename.
+ debug_assert!(validate_basename(basename).is_ok());
+
+ if let Some(entry) = self.entries.get(basename) {
+ match (expect_dir, entry.is_dir) {
+ (true, false) => Err(io::Error::from_raw_os_error(libc::ENOTDIR)),
+ (false, true) => Err(io::Error::from_raw_os_error(libc::EISDIR)),
+ _ => {
+ let inode = entry.inode;
+ let _ = self.entries.remove(basename);
+ Ok(inode)
+ }
+ }
+ } else {
+ Err(io::Error::from_raw_os_error(libc::ENOENT))
+ }
}
fn validate_argument(&self, basename: &Path) -> io::Result<()> {