chore(populateCache): skip if blob already cached

src/populateCache.ts

@@ -4,7 +4,7 @@ import fs from 'fs/promises';
 import git from 'isomorphic-git';
 import http from 'isomorphic-git/http/node';
 
-import { isWriteable, pointsToLFS } from './util';
+import { isVacantAndWriteable, isWriteable, pointsToLFS } from './util';
 import downloadBlobFromPointer from './download';
 import { readPointer } from "./pointers";
 
@@ -55,8 +55,9 @@ export default async function populateCache(workDir: string, ref: string = 'HEAD
             if (pointsToLFS(buff)) {
               const pointer = readPointer({ dir: workDir, content: buff });
 
-              // Don’t even start the download if LFS cache path is not accessible.
-              if (await isWriteable(pointer.objectPath) === false)
+              // Don’t even start the download if LFS cache path is not accessible,
+              // or if it already exists
+              if (await isVacantAndWriteable(pointer.objectPath) === false)
                 return;
 
               const content = await downloadBlobFromPointer(

src/util.ts

@@ -20,12 +20,27 @@ export async function isWriteable(filepath: string): Promise<boolean> {
     await fs.access(filepath, fsConstants.W_OK);
     return true;
   } catch (e) {
-    if ((e as { code: string }).code !== 'ENOENT') {
-      return false;
-    } else {
+    if ((e as { code: string }).code === 'ENOENT') {
+      return true;
+    }
+    return false;
+  }
+}
+
+
+/**
+ * Returns true if given path is available for writing
+ * and not occupied.
+ */
+export async function isVacantAndWriteable(filepath: string): Promise<boolean> {
+  try {
+    await fs.access(filepath, fsConstants.W_OK);
+  } catch (e) {
+    if ((e as { code: string }).code === 'ENOENT') {
       return true;
     }
   }
+  return false;
 }