QFile::rename: use the open file's ID, instead of using the file name

To do that, we needed to add virtual id() in QAbstractFileEngine and
override it in QFSFileEngine. It might be useful to return other types
of IDs for the other file engines, but this commit does not attempt that
just yet.

Change-Id: I1eba2b016de74620bfc8fffd14ccafe0762b3c38
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/src/corelib/io/qabstractfileengine.cpp b/src/corelib/io/qabstractfileengine.cpp
index 9606ec68e9..89727673d3 100644
--- a/src/corelib/io/qabstractfileengine.cpp
+++ b/src/corelib/io/qabstractfileengine.cpp
@@ -678,6 +678,17 @@ bool QAbstractFileEngine::setPermissions(uint perms)
 }
 
 /*!
+    \since 5.9
+
+    Return an identifier that (hopefully) uniquely identifies this file in the
+    system. Returns an invalid QByteArray() if that cannot be calculated.
+*/
+QByteArray QAbstractFileEngine::id() const
+{
+    return QByteArray();
+}
+
+/*!
     Return  the file engine's current file name in the format
     specified by \a file.