Defer application of init.meta.json until after init Lua files. (#549)

Fixes #546.

src/snapshot_middleware/dir.rs

@@ -10,6 +10,40 @@ pub fn snapshot_dir(
     context: &InstanceContext,
     vfs: &Vfs,
     path: &Path,
+) -> anyhow::Result<Option<InstanceSnapshot>> {
+    let mut snapshot = match snapshot_dir_no_meta(context, vfs, path)? {
+        Some(snapshot) => snapshot,
+        None => return Ok(None),
+    };
+
+    if let Some(mut meta) = dir_meta(vfs, path)? {
+        meta.apply_all(&mut snapshot)?;
+    }
+
+    Ok(Some(snapshot))
+}
+
+/// Retrieves the meta file that should be applied for this directory, if it
+/// exists.
+pub fn dir_meta(vfs: &Vfs, path: &Path) -> anyhow::Result<Option<DirectoryMetadata>> {
+    let meta_path = path.join("init.meta.json");
+
+    if let Some(meta_contents) = vfs.read(&meta_path).with_not_found()? {
+        let metadata = DirectoryMetadata::from_slice(&meta_contents, meta_path)?;
+        Ok(Some(metadata))
+    } else {
+        Ok(None)
+    }
+}
+
+/// Snapshot a directory without applying meta files; useful for if the
+/// directory's ClassName will change before metadata should be applied. For
+/// example, this can happen if the directory contains an `init.client.lua`
+/// file.
+pub fn snapshot_dir_no_meta(
+    context: &InstanceContext,
+    vfs: &Vfs,
+    path: &Path,
 ) -> anyhow::Result<Option<InstanceSnapshot>> {
     let passes_filter_rules = |child: &DirEntry| {
         context
@@ -52,7 +86,7 @@ pub fn snapshot_dir(
         path.join("init.client.lua"),
     ];
 
-    let mut snapshot = InstanceSnapshot::new()
+    let snapshot = InstanceSnapshot::new()
         .name(instance_name)
         .class_name("Folder")
         .children(snapshot_children)
@@ -63,11 +97,6 @@ pub fn snapshot_dir(
                 .context(context),
         );
 
-    if let Some(meta_contents) = vfs.read(&meta_path).with_not_found()? {
-        let mut metadata = DirectoryMetadata::from_slice(&meta_contents, meta_path)?;
-        metadata.apply_all(&mut snapshot)?;
-    }
-
     Ok(Some(snapshot))
 }