Migrate fd_renumber

crates/wasi-common/src/snapshots/wasi_snapshot_preview1.rs

@@ -289,8 +289,28 @@ impl<'a> WasiSnapshotPreview1 for WasiCtx {
         unimplemented!("fd_readdir")
     }
 
-    fn fd_renumber(&self, _fd: types::Fd, _to: types::Fd) -> Result<()> {
-        unimplemented!("fd_renumber")
+    fn fd_renumber(&self, from: types::Fd, to: types::Fd) -> Result<()> {
+        trace!("fd_renumber(from={:?}, to={:?})", from, to);
+
+        if unsafe { !self.contains_entry(from) } {
+            return Err(Errno::Badf);
+        }
+
+        // Don't allow renumbering over a pre-opened resource.
+        // TODO: Eventually, we do want to permit this, once libpreopen in
+        // userspace is capable of removing entries from its tables as well.
+        let from_fe = unsafe { self.get_entry(from)? };
+        if from_fe.preopen_path.is_some() {
+            return Err(Errno::Notsup);
+        }
+        if let Ok(to_fe) = unsafe { self.get_entry(to) } {
+            if to_fe.preopen_path.is_some() {
+                return Err(Errno::Notsup);
+            }
+        }
+        let fe = self.remove_entry(from)?;
+        self.insert_entry_at(to, fe);
+        Ok(())
     }
 
     fn fd_seek(