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Fix QFSFileEngine::renameOverwrite for Windows Embedded Compact 7. 

Windows Embedded Compact 7 does not have MoveFileEx, simulate it with
the available file I/O functions [1]. For more details please check the
comments in source code.

[1] http://msdn.microsoft.com/en-us/library/ee490588.aspx

Change-Id: Ib0fb0ba84e2d070dee2f633af1b81bec132f4c17
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Andreas Holzammer <andreas.holzammer@kdab.com>
Reviewed-by: Johannes Oikarinen <johannes.oikarinen@digia.com>
bb10
Janne Anttila 2013-03-20 10:16:24 +02:00 committed by The Qt Project
parent 59f1152ec7
commit aa009e3dcc
1 changed files with 26 additions and 0 deletions
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26
src/corelib/io/qfsfileengine_win.cpp
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@ -520,9 +520,35 @@ bool QFSFileEngine::rename(const QString &newName)
bool QFSFileEngine::renameOverwrite(const QString &newName)
{
Q_D(QFSFileEngine);
#if defined(Q_OS_WINCE)
// Windows Embedded Compact 7 does not have MoveFileEx, simulate it with the following sequence:
// 1. DeleteAndRenameFile (Should work on RAM FS when both files exist)
// 2. DeleteFile/MoveFile (Should work on all file systems)
//
// DeleteFile/MoveFile fallback implementation violates atomicity, but it is more acceptable than
// alternative CopyFile/DeleteFile sequence for the following reasons:
//
// 1. DeleteFile/MoveFile is way faster than CopyFile/DeleteFile and thus more atomic.
// 2. Given the intended use case of this function in QSaveFile, DeleteFile/MoveFile sequence will
// delete the old content, but leave a file "filename.ext.XXXXXX" in the same directory if MoveFile fails.
// With CopyFile/DeleteFile sequence, it can happen that new data is partially copied to target file
// (because CopyFile is not atomic either), thus leaving *some* content to target file.
// This makes the need for application level recovery harder to detect than in DeleteFile/MoveFile
// sequence where target file simply does not exist.
//
bool ret = ::DeleteAndRenameFile((wchar_t*)QFileSystemEntry(newName).nativeFilePath().utf16(),
(wchar_t*)d->fileEntry.nativeFilePath().utf16()) != 0;
if (!ret) {
ret = ::DeleteFile((wchar_t*)d->fileEntry.nativeFilePath().utf16()) != 0;
if (ret)
ret = ::MoveFile((wchar_t*)d->fileEntry.nativeFilePath().utf16(),
(wchar_t*)QFileSystemEntry(newName).nativeFilePath().utf16()) != 0;
}
#else
bool ret = ::MoveFileEx((wchar_t*)d->fileEntry.nativeFilePath().utf16(),
(wchar_t*)QFileSystemEntry(newName).nativeFilePath().utf16(),
MOVEFILE_REPLACE_EXISTING) != 0;
#endif
if (!ret)
setError(QFile::RenameError, QSystemError(::GetLastError(), QSystemError::NativeError).toString());
return ret;