Set the state of QTemporaryFileEngine properly prior to reopening

QTemporaryFileEngine does not store the pattern, so it needs to get it
again from QTemporaryFilePrivate prior to reopening the file. It's
possible to lose the pattern when remove() is called on the object.

Task-number: QTBUG-46156
Change-Id: I66a35ce5f88941f29aa6ffff13dfc7f83d4fa3a2
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
Reviewed-by: David Faure <david.faure@kdab.com>

3 files changed, 28 insertions, 14 deletions

diff --git a/src/corelib/io/qsavefile.cpp b/src/corelib/io/qsavefile.cpp
index ffa6ad1c55..5a325f8e2c 100644
--- a/src/corelib/io/qsavefile.cpp
+++ b/src/corelib/io/qsavefile.cpp
@@ -215,7 +215,8 @@ bool QSaveFile::open(OpenMode mode)
             d->finalFileName = existingFile.filePath();
     }
 
-    d->fileEngine = new QTemporaryFileEngine(d->finalFileName, 0666);
+    d->fileEngine = new QTemporaryFileEngine;
+    static_cast<QTemporaryFileEngine *>(d->fileEngine)->initialize(d->finalFileName, 0666);
     // Same as in QFile: QIODevice provides the buffering, so there's no need to request it from the file engine.
     if (!d->fileEngine->open(mode | QIODevice::Unbuffered)) {
         QFileDevice::FileError err = d->fileEngine->error();
diff --git a/src/corelib/io/qtemporaryfile.cpp b/src/corelib/io/qtemporaryfile.cpp
index 556bc6e760..68ac85fffd 100644
--- a/src/corelib/io/qtemporaryfile.cpp
+++ b/src/corelib/io/qtemporaryfile.cpp
@@ -409,14 +409,24 @@ QTemporaryFilePrivate::~QTemporaryFilePrivate()
 QAbstractFileEngine *QTemporaryFilePrivate::engine() const
 {
     if (!fileEngine) {
-        if (fileName.isEmpty())
-            fileEngine = new QTemporaryFileEngine(templateName, 0600);
-        else
-            fileEngine = new QTemporaryFileEngine(fileName, 0600, false);
+        fileEngine = new QTemporaryFileEngine;
+        resetFileEngine();
     }
     return fileEngine;
 }
 
+void QTemporaryFilePrivate::resetFileEngine() const
+{
+    if (!fileEngine)
+        return;
+
+    QTemporaryFileEngine *tef = static_cast<QTemporaryFileEngine *>(fileEngine);
+    if (fileName.isEmpty())
+        tef->initialize(templateName, 0600);
+    else
+        tef->initialize(fileName, 0600, false);
+}
+
 QString QTemporaryFilePrivate::defaultTemplateName()
 {
     QString baseName;
@@ -769,6 +779,13 @@ bool QTemporaryFile::open(OpenMode flags)
         }
     }
 
+    // reset the engine state so it creates a new, unique file name from the template;
+    // equivalent to:
+    //    delete d->fileEngine;
+    //    d->fileEngine = 0;
+    //    d->engine();
+    d->resetFileEngine();
+
     if (QFile::open(flags)) {
         d->fileName = d->fileEngine->fileName(QAbstractFileEngine::DefaultName);
         return true;
diff --git a/src/corelib/io/qtemporaryfile_p.h b/src/corelib/io/qtemporaryfile_p.h
index 475298f264..2d4468fcf8 100644
--- a/src/corelib/io/qtemporaryfile_p.h
+++ b/src/corelib/io/qtemporaryfile_p.h
@@ -64,6 +64,7 @@ protected:
     ~QTemporaryFilePrivate();
 
     QAbstractFileEngine *engine() const;
+    void resetFileEngine() const;
 
     bool autoRemove;
     QString templateName;
@@ -77,22 +78,17 @@ class QTemporaryFileEngine : public QFSFileEngine
 {
     Q_DECLARE_PRIVATE(QFSFileEngine)
 public:
-
-    QTemporaryFileEngine(const QString &file,
-                         quint32 fileMode,
-                         bool fileIsTemplate = true) :
-        QFSFileEngine(),
-        fileMode(fileMode),
-        filePathIsTemplate(fileIsTemplate),
-        filePathWasTemplate(fileIsTemplate)
+    void initialize(const QString &file, quint32 mode, bool nameIsTemplate = true)
     {
         Q_D(QFSFileEngine);
+        Q_ASSERT(!isReallyOpen());
+        fileMode = mode;
+        filePathIsTemplate = filePathWasTemplate = nameIsTemplate;
         d->fileEntry = QFileSystemEntry(file);
 
         if (!filePathIsTemplate)
             QFSFileEngine::setFileName(file);
     }
-
     ~QTemporaryFileEngine();
 
     bool isReallyOpen();