add directory rename

crates/wasi-c2/TEST_FAILURES

@@ -12,11 +12,8 @@ wasi_tests::path_filestat
     - fdstat.fs_flags is not populated correctly
 wasi_tests::path_link
     - path_link is not implemented
-wasi_tests::path_rename
-    - path_rename is not implemented. we need to be able to downcast a dyn
-      WasiDir to a concrete Dir for this to be possible - need to reintroduce Any to hierarchy
 wasi_tests::path_rename_trailing_slashes
-    - path_rename is not implemented
+    - unclear, trailing slash behavior is wrong
 wasi_tests::path_symlink_trailing_slashes
     - unclear, path_symlink is giving a ENOTDIR when it expects an EEXIST...
 wasi_tests::poll_oneoff

crates/wasi-c2/src/dir.rs

@@ -1,10 +1,12 @@
 use crate::error::Error;
 use crate::file::{FdFlags, FileCaps, FileType, Filestat, OFlags, WasiFile};
+use std::any::Any;
 use std::convert::TryInto;
 use std::ops::Deref;
 use std::path::{Path, PathBuf};
 
 pub trait WasiDir {
+    fn as_any(&self) -> &dyn Any;
     fn open_file(
         &self,
         symlink_follow: bool,
@@ -24,6 +26,7 @@ pub trait WasiDir {
     fn unlink_file(&self, path: &str) -> Result<(), Error>;
     fn read_link(&self, path: &str) -> Result<PathBuf, Error>;
     fn get_filestat(&self) -> Result<Filestat, Error>;
+    fn rename(&self, path: &str, dest_dir: &dyn WasiDir, dest_path: &str) -> Result<(), Error>;
 }
 
 pub(crate) struct DirEntry {
@@ -196,6 +199,9 @@ impl From<ReaddirCursor> for u64 {
 }
 
 impl WasiDir for cap_std::fs::Dir {
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
     fn open_file(
         &self,
         symlink_follow: bool,
@@ -349,4 +355,12 @@ impl WasiDir for cap_std::fs::Dir {
             ctim: meta.created().map(|t| Some(t.into_std())).unwrap_or(None),
         })
     }
+    fn rename(&self, src_path: &str, dest_dir: &dyn WasiDir, dest_path: &str) -> Result<(), Error> {
+        let dest_dir = dest_dir
+            .as_any()
+            .downcast_ref::<Self>()
+            .ok_or(Error::NotCapable)?;
+        self.rename(Path::new(src_path), dest_dir, Path::new(dest_path))?;
+        Ok(())
+    }
 }

crates/wasi-c2/src/snapshots/preview_1.rs

@@ -771,14 +771,21 @@ impl<'a> wasi_snapshot_preview1::WasiSnapshotPreview1 for WasiCtx {
 
     fn path_rename(
         &self,
-        old_fd: types::Fd,
-        old_path: &GuestPtr<'_, str>,
-        new_fd: types::Fd,
-        new_path: &GuestPtr<'_, str>,
+        src_fd: types::Fd,
+        src_path: &GuestPtr<'_, str>,
+        dest_fd: types::Fd,
+        dest_path: &GuestPtr<'_, str>,
     ) -> Result<(), Error> {
-        // XXX: Dir::rename requires (to_dir: &Self), but in the table we just have a dyn WasiDir.
-        // The downcast isn't possible.
-        unimplemented!()
+        let table = self.table();
+        let src_entry: Ref<DirEntry> = table.get(u32::from(src_fd))?;
+        let src_dir = src_entry.get_cap(DirCaps::RENAME_SOURCE)?;
+        let dest_entry: Ref<DirEntry> = table.get(u32::from(dest_fd))?;
+        let dest_dir = dest_entry.get_cap(DirCaps::RENAME_TARGET)?;
+        src_dir.rename(
+            src_path.as_str()?.deref(),
+            dest_dir.deref(),
+            dest_path.as_str()?.deref(),
+        )
     }
 
     fn path_symlink(