dev: decouple FSEntryFetcher by adding hasChild

Adding the hasChild method of FSNodeContext as well as a corresponding
method to filesystem providers is prerequisite to moving
FSEntryFetcher's logic into the new puterfs extension.

extensions/puterfs/PuterFSProvider.js

@@ -614,6 +614,17 @@ export default class PuterFSProvider {
         return child_uuids;
     }
 
+    async directory_has_name ({ parent, name }) {
+        const uid = await parent.get('uid');
+        /* eslint-disable */
+        let check_dupe = await db.read(
+            'SELECT `id` FROM `fsentries` WHERE `parent_uid` = ? AND name = ? LIMIT 1',
+            [uid, name],
+        );
+        /* eslint-enable */
+        return !!check_dupe[0];
+    }
+
     /**
      * Write a new file to the filesystem. Throws an error if the destination
      * already exists.

src/backend/src/filesystem/FSNodeContext.js

@@ -614,6 +614,10 @@ module.exports = class FSNodeContext {
         }
 
         if ( key === 'uid' ) {
+            const uidSelector = this.get_selector_of_type(NodeUIDSelector);
+            if ( uidSelector ) {
+                return uidSelector.value;
+            }
             await this.fetchEntry();
             return this.uid;
         }
@@ -737,6 +741,10 @@ module.exports = class FSNodeContext {
 
         return await this.fs.node(new NodeChildSelector(this.selector, name));
     }
+    
+    async hasChild(name) {
+        return await this.provider.directory_has_name({ parent: this, name });
+    }
 
     async getTarget() {
         await this.fetchEntry();

src/backend/src/filesystem/hl_operations/hl_copy.js

@@ -173,14 +173,11 @@ class HLCopy extends HLFilesystemOperation {
             }
 
             if ( values.dedupe_name ) {
-                const fsEntryFetcher = context.get('services').get('fsEntryFetcher');
                 const target_ext = _path.extname(target_name);
                 const target_noext = _path.basename(target_name, target_ext);
                 for ( let i=1 ;; i++ ) {
                     const try_new_name = `${target_noext} (${i})${target_ext}`;
-                    const exists = await fsEntryFetcher.nameExistsUnderParent(
-                        parent.uid, try_new_name
-                    );
+                    const exists = await parent.hasChild(try_new_name);
                     if ( ! exists ) {
                         target_name = try_new_name;
                         break;

src/backend/src/filesystem/hl_operations/hl_move.js

@@ -152,14 +152,11 @@ class HLMove extends HLFilesystemOperation {
             }
 
             if ( values.dedupe_name ) {
-                const svc_fsEntryFetcher = svc.get('fsEntryFetcher');
                 const target_ext = _path.extname(target_name);
                 const target_noext = _path.basename(target_name, target_ext);
                 for ( let i=1 ;; i++ ) {
                     const try_new_name = `${target_noext} (${i})${target_ext}`;
-                    const exists = await svc_fsEntryFetcher.nameExistsUnderParent(
-                        parent.uid, try_new_name
-                    );
+                    const exists = await parent.hasChild(try_new_name);
                     if ( ! exists ) {
                         target_name = try_new_name;
                         break;

src/backend/src/filesystem/hl_operations/hl_write.js

@@ -251,9 +251,7 @@ class HLWrite extends HLFilesystemOperation {
                 const target_noext = _path.basename(target_name, target_ext);
                 for ( let i=1 ;; i++ ) {
                     const try_new_name = `${target_noext} (${i})${target_ext}`;
-                    const exists = await fsEntryFetcher.nameExistsUnderParent(
-                        parent.uid, try_new_name
-                    );
+                    const exists = await parent.hasChild(try_new_name);
                     if ( ! exists ) {
                         target_name = try_new_name;
                         break;