QFileInfo: Fail faster when stat'ing filepath on a disconnected drive

The Windows implementation of QFileSystemEngine tries hard to fill the
metadata for a file, even if GetFileAttributesEx returns with error.
This is good in many situations, but when the error code indicates that
the drive on which the file resides has been disconnected, then we
should fail quickly.

Task-number: QTBUG-6039
Pick-to: 5.15
Change-Id: I7574c5a2e524e913306d0b470b4f227416442c13
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

1 files changed, 8 insertions, 6 deletions

diff --git a/src/corelib/io/qfilesystemengine_win.cpp b/src/corelib/io/qfilesystemengine_win.cpp
index 4e7824522c..1c99f07400 100644
--- a/src/corelib/io/qfilesystemengine_win.cpp
+++ b/src/corelib/io/qfilesystemengine_win.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2020 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the QtCore module of the Qt Toolkit.
@@ -1062,11 +1062,13 @@ bool QFileSystemEngine::fillMetaData(const QFileSystemEntry &entry, QFileSystemM
         if (ok) {
             data.fillFromFindData(findData, false, fname.isDriveRoot());
         } else {
-            if (!tryFindFallback(fname, data))
-                if (!tryDriveUNCFallback(fname, data)) {
-                    SetErrorMode(oldmode);
-                    return false;
-                }
+            const DWORD lastError = GetLastError();
+            if (lastError == ERROR_LOGON_FAILURE || lastError == ERROR_BAD_NETPATH // disconnected drive
+                || (!tryFindFallback(fname, data) && !tryDriveUNCFallback(fname, data))) {
+                data.clearFlags();
+                SetErrorMode(oldmode);
+                return false;
+            }
         }
         SetErrorMode(oldmode);
     }