QSaveFile: Fix changing the file name after hitting on readonly file

The call to QFileDevice::unsetError() in QSaveFile::open() does
not clear QSaveFilePrivate::writeError. Clear it in addition.

Fixes: QTBUG-77007
Change-Id: I5e5009750f1726d1c74c1b4eb1c33f3a5393fe4f
Reviewed-by: David Faure <david.faure@kdab.com>

2 files changed, 35 insertions, 0 deletions

diff --git a/src/corelib/io/qsavefile.cpp b/src/corelib/io/qsavefile.cpp
index 0cbc8c2234..fac8892da2 100644
--- a/src/corelib/io/qsavefile.cpp
+++ b/src/corelib/io/qsavefile.cpp
@@ -197,6 +197,7 @@ bool QSaveFile::open(OpenMode mode)
         return false;
     }
     unsetError();
+    d->writeError = QFileDevice::NoError;
     if ((mode & (ReadOnly | WriteOnly)) == 0) {
         qWarning("QSaveFile::open: Open mode not specified");
         return false;
diff --git a/tests/auto/corelib/io/qsavefile/tst_qsavefile.cpp b/tests/auto/corelib/io/qsavefile/tst_qsavefile.cpp
index 96970421d3..f1327933c4 100644
--- a/tests/auto/corelib/io/qsavefile/tst_qsavefile.cpp
+++ b/tests/auto/corelib/io/qsavefile/tst_qsavefile.cpp
@@ -72,6 +72,7 @@ public slots:
 
 private slots:
     void transactionalWrite();
+    void retryTransactionalWrite();
     void textStreamManualFlush();
     void textStreamAutoFlush();
     void saveTwice();
@@ -129,6 +130,39 @@ void tst_QSaveFile::transactionalWrite()
     QCOMPARE(QFile::permissions(targetFile), QFile::permissions(otherFile));
 }
 
+// QTBUG-77007: Simulate the case of an application with a loop prompting
+// to retry saving on failure. Create a read-only file first (Unix only)
+void tst_QSaveFile::retryTransactionalWrite()
+{
+#ifndef Q_OS_UNIX
+    QSKIP("This test is Unix only");
+#endif
+    QTemporaryDir dir;
+    QVERIFY2(dir.isValid(), qPrintable(dir.errorString()));
+
+    QString targetFile = dir.path() + QLatin1String("/outfile");
+    const QString readOnlyName = targetFile + QLatin1String(".ro");
+    {
+        QFile readOnlyFile(readOnlyName);
+        QVERIFY2(readOnlyFile.open(QIODevice::WriteOnly), msgCannotOpen(readOnlyFile).constData());
+        readOnlyFile.write("Hello");
+        readOnlyFile.close();
+        auto permissions = readOnlyFile.permissions();
+        permissions &= ~(QFileDevice::WriteOwner | QFileDevice::WriteGroup | QFileDevice::WriteUser);
+        QVERIFY(readOnlyFile.setPermissions(permissions));
+    }
+
+    QSaveFile file(readOnlyName);
+    QVERIFY(!file.open(QIODevice::WriteOnly));
+
+    file.setFileName(targetFile);
+    QVERIFY2(file.open(QIODevice::WriteOnly), msgCannotOpen(file).constData());
+    QVERIFY(file.isOpen());
+    QCOMPARE(file.write("Hello"), Q_INT64_C(5));
+    QCOMPARE(file.error(), QFile::NoError);
+    QVERIFY(file.commit());
+}
+
 void tst_QSaveFile::saveTwice()
 {
     // Check that we can reuse a QSaveFile object