Ensure QTemporaryFile can create files when an identical dir exists.

When QTemporaryFile attempts to create a new file in
createFileFromTemplate, it fails if the filename exists and is a
directory. Windows returns error code 5 (ERROR_ACCESS_DENIED) in this
case - rather than ERROR_FILE_EXISTS - which is not handled.

This patch handles ERROR_ACCESS_DENIED in addition to the already
handled ERROR_FILE_EXISTS, meaning that QTemporaryFile will continue
to look for unique names when a directory with the same name exists.

Task-number: QTBUG-30058

Change-Id: I42339887d7f5483e3dc6a03a9da15111c350da8f
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: David Faure <david.faure@kdab.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>

2 files changed, 43 insertions, 1 deletions

diff --git a/src/corelib/io/qtemporaryfile.cpp b/src/corelib/io/qtemporaryfile.cpp
index d3a6e3c238..c2f421843c 100644
--- a/src/corelib/io/qtemporaryfile.cpp
+++ b/src/corelib/io/qtemporaryfile.cpp
@@ -160,7 +160,14 @@ static bool createFileFromTemplate(NativeFileHandle &file,
             return true;
 
         DWORD err = GetLastError();
-        if (err != ERROR_FILE_EXISTS) {
+        if (err == ERROR_ACCESS_DENIED) {
+            DWORD attributes = GetFileAttributes((const wchar_t *)path.constData());
+            if (attributes == INVALID_FILE_ATTRIBUTES) {
+                // Potential write error (read-only parent directory, etc.).
+                error = QSystemError(err, QSystemError::NativeError);
+                return false;
+            } // else file already exists as a directory.
+        } else if (err != ERROR_FILE_EXISTS) {
             error = QSystemError(err, QSystemError::NativeError);
             return false;
         }
diff --git a/tests/auto/corelib/io/qtemporaryfile/tst_qtemporaryfile.cpp b/tests/auto/corelib/io/qtemporaryfile/tst_qtemporaryfile.cpp
index 28cf7a904a..6eb6f83d2a 100644
--- a/tests/auto/corelib/io/qtemporaryfile/tst_qtemporaryfile.cpp
+++ b/tests/auto/corelib/io/qtemporaryfile/tst_qtemporaryfile.cpp
@@ -92,6 +92,7 @@ private slots:
     void createNativeFile();
     void QTBUG_4796_data();
     void QTBUG_4796();
+    void guaranteeUnique();
 };
 
 void tst_QTemporaryFile::initTestCase()
@@ -782,5 +783,39 @@ void tst_QTemporaryFile::QTBUG_4796()
     cleaner.reset();
 }
 
+void tst_QTemporaryFile::guaranteeUnique()
+{
+    QDir dir(QDir::tempPath());
+    QString takenFileName;
+
+    // First pass. See which filename QTemporaryFile will try first.
+    {
+        // Fix the random seed.
+        qsrand(1135);
+        QTemporaryFile tmpFile("testFile1.XXXXXX");
+        tmpFile.open();
+        takenFileName = tmpFile.fileName();
+        QVERIFY(QFile::exists(takenFileName));
+    }
+
+    QVERIFY(!QFile::exists(takenFileName));
+
+    // Create a directory with same name.
+    QVERIFY(dir.mkdir(takenFileName));
+
+    // Second pass, now we have blocked its first attempt with a directory.
+    {
+        // Fix the random seed.
+        qsrand(1135);
+        QTemporaryFile tmpFile("testFile1.XXXXXX");
+        QVERIFY(tmpFile.open());
+        QString uniqueFileName = tmpFile.fileName();
+        QVERIFY(QFileInfo(uniqueFileName).isFile());
+        QVERIFY(uniqueFileName != takenFileName);
+    }
+
+    QVERIFY(dir.rmdir(takenFileName));
+}
+
 QTEST_MAIN(tst_QTemporaryFile)
 #include "tst_qtemporaryfile.moc"