add check for existing symlink

Signed-off-by: Anton Troshin <anton@diagrid.io>

src/installer.ts

@@ -223,7 +223,7 @@ async function cacheWindowsDir(
   }
 
   core.info(`Found Cache Directory Paths: ${cacheDirectoryPaths}`);
-  
+
   // replace cache directory path with actual cache directory path
   const actualCacheDirectoryPaths = cacheDirectoryPaths.map(path => {
     return {
@@ -232,17 +232,24 @@ async function cacheWindowsDir(
     };
   });
 
-  // iterate through actual cache directory paths and make links
+  // iterate through actual cache directory paths and make links if necessary
   for (const cachePath of actualCacheDirectoryPaths) {
     if (!fs.existsSync(cachePath.actualPath)) {
       core.info(`Creating directory ${cachePath.actualPath}`);
       fs.mkdirSync(path.dirname(cachePath.actualPath), {recursive: true});
+    } else {
+      core.info(`Directory ${cachePath.actualPath} already exists`);
+      // make sure the link is pointing to the actual cache directory
+      let symlinkTarget = fs.readlinkSync(cachePath.defaultPath);
+      if (symlinkTarget !== "") {
+        core.info(`Found link ${cachePath.defaultPath} => ${symlinkTarget}`);
+      } else {
+        fs.symlinkSync(cachePath.actualPath, cachePath.defaultPath, 'junction');
+        core.info(
+          `Created link ${cachePath.defaultPath} => ${cachePath.actualPath}`
+        );
+      }
     }
-
-    fs.symlinkSync(cachePath.actualPath, cachePath.defaultPath, 'junction');
-    core.info(
-      `Created link ${cachePath.defaultPath} => ${cachePath.actualPath}`
-    );
   }
 
   // make outer code to continue using toolcache as if it were installed on c: