handle trimming '/' if present in the object names (#11765)

- MultipleDeletes should handle '/' prefix for objectnames
- Trimming the slash alone is enough for ListObjects()
  prefix and markers

fixes #11769

cmd/bucket-handlers.go

@@ -411,6 +411,11 @@ func (api objectAPIHandlers) DeleteMultipleObjectsHandler(w http.ResponseWriter,
 		return
 	}
 
+	// Convert object name delete objects if it has `/` in the beginning.
+	for i := range deleteObjects.Objects {
+		deleteObjects.Objects[i].ObjectName = trimLeadingSlash(deleteObjects.Objects[i].ObjectName)
+	}
+
 	// Call checkRequestAuthType to populate ReqInfo.AccessKey before GetBucketInfo()
 	// Ignore errors here to preserve the S3 error behavior of GetBucketInfo()
 	checkRequestAuthType(ctx, r, policy.DeleteObjectAction, bucket, "")
@@ -853,13 +858,7 @@ func (api objectAPIHandlers) PostPolicyBucketHandler(w http.ResponseWriter, r *h
 		// by the filename attribute passed in multipart
 		formValues.Set("Key", strings.Replace(formValues.Get("Key"), "${filename}", fileName, -1))
 	}
-	object := formValues.Get("Key")
-
-	object, err = unescapePath(object)
-	if err != nil {
-		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
-		return
-	}
+	object := trimLeadingSlash(formValues.Get("Key"))
 
 	successRedirect := formValues.Get("success_action_redirect")
 	successStatus := formValues.Get("success_action_status")