1 files changed, 37 insertions, 8 deletions

diff --git a/src/corelib/io/qsavefile.cpp b/src/corelib/io/qsavefile.cpp
index 3f45ca5f91..56934a9a0f 100644
--- a/src/corelib/io/qsavefile.cpp
+++ b/src/corelib/io/qsavefile.cpp
@@ -184,7 +184,8 @@ void QSaveFile::setFileName(const QString &name)
     Important: the \a mode must include QIODevice::WriteOnly.
     It may also have additional flags, such as QIODevice::Text and QIODevice::Unbuffered.
 
-    QIODevice::ReadWrite and QIODevice::Append are not supported at the moment.
+    QIODevice::ReadWrite, QIODevice::Append, QIODevice::NewOnly and
+    QIODevice::ExistingOnly are not supported at the moment.
 
     \sa QIODevice::OpenMode, setFileName()
 */
@@ -201,7 +202,8 @@ bool QSaveFile::open(OpenMode mode)
         return false;
     }
     // In the future we could implement ReadWrite by copying from the existing file to the temp file...
-    if ((mode & ReadOnly) || (mode & Append)) {
+    // The implications of NewOnly and ExistingOnly when used with QSaveFile need to be considered carefully...
+    if (mode & (ReadOnly | Append | NewOnly | ExistingOnly)) {
         qWarning("QSaveFile::open: Unsupported open mode 0x%x", int(mode));
         return false;
     }
@@ -231,7 +233,38 @@ bool QSaveFile::open(OpenMode mode)
             d->finalFileName = existingFile.filePath();
     }
 
-    d->fileEngine = new QTemporaryFileEngine;
+    auto openDirectly = [&]() {
+        d->fileEngine = QAbstractFileEngine::create(d->finalFileName);
+        if (d->fileEngine->open(mode | QIODevice::Unbuffered)) {
+            d->useTemporaryFile = false;
+            QFileDevice::open(mode);
+            return true;
+        }
+        return false;
+    };
+
+#ifdef Q_OS_WIN
+    // check if it is an Alternate Data Stream
+    if (d->finalFileName == d->fileName && d->fileName.indexOf(QLatin1Char(':'), 2) > 1) {
+        // yes, we can't rename onto it...
+        if (d->directWriteFallback) {
+            if (openDirectly())
+                return true;
+            d->setError(d->fileEngine->error(), d->fileEngine->errorString());
+            delete d->fileEngine;
+            d->fileEngine = 0;
+        } else {
+            QString msg =
+                    QSaveFile::tr("QSaveFile cannot open '%1' without direct write fallback "
+                                  "enabled: path contains an Alternate Data Stream specifier")
+                    .arg(QDir::toNativeSeparators(d->fileName));
+            d->setError(QFileDevice::OpenError, msg);
+        }
+        return false;
+    }
+#endif
+
+    d->fileEngine = new QTemporaryFileEngine(&d->finalFileName);
     // if the target file exists, we'll copy its permissions below,
     // but until then, let's ensure the temporary file is not accessible
     // to a third party
@@ -243,12 +276,8 @@ bool QSaveFile::open(OpenMode mode)
 #ifdef Q_OS_UNIX
         if (d->directWriteFallback && err == QFileDevice::OpenError && errno == EACCES) {
             delete d->fileEngine;
-            d->fileEngine = QAbstractFileEngine::create(d->finalFileName);
-            if (d->fileEngine->open(mode | QIODevice::Unbuffered)) {
-                d->useTemporaryFile = false;
-                QFileDevice::open(mode);
+            if (openDirectly())
                 return true;
-            }
             err = d->fileEngine->error();
         }
 #endif