Add syncToDisk() to QAbstractFileEngine.

This is needed by QSaveFile.

Change-Id: I07ebdfd832c0be65c26f0aed1bb7852ac33135ca
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

6 files changed, 58 insertions, 4 deletions

diff --git a/src/corelib/io/qabstractfileengine.cpp b/src/corelib/io/qabstractfileengine.cpp
index b12dc47c52..e046119fe2 100644
--- a/src/corelib/io/qabstractfileengine.cpp
+++ b/src/corelib/io/qabstractfileengine.cpp
@@ -400,6 +400,19 @@ bool QAbstractFileEngine::close()
 }
 
 /*!
+    \since 5.1
+
+    Flushes and syncs the file to disk.
+
+    Returns true if successful; otherwise returns false.
+    The default implementation always returns false.
+*/
+bool QAbstractFileEngine::syncToDisk()
+{
+    return false;
+}
+
+/*!
     Flushes the open file, returning true if successful; otherwise returns
     false.
 
diff --git a/src/corelib/io/qabstractfileengine_p.h b/src/corelib/io/qabstractfileengine_p.h
index 2cbd927968..5106c01be9 100644
--- a/src/corelib/io/qabstractfileengine_p.h
+++ b/src/corelib/io/qabstractfileengine_p.h
@@ -124,6 +124,7 @@ public:
     virtual bool open(QIODevice::OpenMode openMode);
     virtual bool close();
     virtual bool flush();
+    virtual bool syncToDisk();
     virtual qint64 size() const;
     virtual qint64 pos() const;
     virtual bool seek(qint64 pos);
diff --git a/src/corelib/io/qfsfileengine.cpp b/src/corelib/io/qfsfileengine.cpp
index 1bc3a7da2e..11cbda14ca 100644
--- a/src/corelib/io/qfsfileengine.cpp
+++ b/src/corelib/io/qfsfileengine.cpp
@@ -419,6 +419,17 @@ bool QFSFileEngine::flush()
 }
 
 /*!
+    \reimp
+*/
+bool QFSFileEngine::syncToDisk()
+{
+    Q_D(QFSFileEngine);
+    if ((d->openMode & QIODevice::WriteOnly) == 0)
+        return true;
+    return d->nativeSyncToDisk();
+}
+
+/*!
     \internal
 */
 bool QFSFileEnginePrivate::flushFh()
diff --git a/src/corelib/io/qfsfileengine_p.h b/src/corelib/io/qfsfileengine_p.h
index cf70032134..5d3a6a3767 100644
--- a/src/corelib/io/qfsfileengine_p.h
+++ b/src/corelib/io/qfsfileengine_p.h
@@ -81,6 +81,7 @@ public:
     bool open(QIODevice::OpenMode flags, FILE *fh);
     bool close();
     bool flush();
+    bool syncToDisk();
     qint64 size() const;
     qint64 pos() const;
     bool seek(qint64);
@@ -150,6 +151,7 @@ public:
     bool nativeClose();
     bool closeFdFh();
     bool nativeFlush();
+    bool nativeSyncToDisk();
     bool flushFh();
     qint64 nativeSize() const;
 #ifndef Q_OS_WIN
diff --git a/src/corelib/io/qfsfileengine_unix.cpp b/src/corelib/io/qfsfileengine_unix.cpp
index 8f622d77cd..05b55525b6 100644
--- a/src/corelib/io/qfsfileengine_unix.cpp
+++ b/src/corelib/io/qfsfileengine_unix.cpp
@@ -258,6 +258,23 @@ bool QFSFileEnginePrivate::nativeFlush()
 
 /*!
     \internal
+    \since 5.1
+*/
+bool QFSFileEnginePrivate::nativeSyncToDisk()
+{
+    Q_Q(QFSFileEngine);
+#if defined(_POSIX_SYNCHRONIZED_IO) && _POSIX_SYNCHRONIZED_IO > 0
+    const int ret = fdatasync(nativeHandle());
+#else
+    const int ret = fsync(nativeHandle());
+#endif
+    if (ret != 0)
+        q->setError(QFile::WriteError, qt_error_string(errno));
+    return ret == 0;
+}
+
+/*!
+    \internal
 */
 qint64 QFSFileEnginePrivate::nativeRead(char *data, qint64 len)
 {
diff --git a/src/corelib/io/qfsfileengine_win.cpp b/src/corelib/io/qfsfileengine_win.cpp
index 86e9bf971d..756e884bd1 100644
--- a/src/corelib/io/qfsfileengine_win.cpp
+++ b/src/corelib/io/qfsfileengine_win.cpp
@@ -198,15 +198,25 @@ bool QFSFileEnginePrivate::nativeFlush()
         return true;
     }
 
-    // Windows native mode; flushing is
-    // unnecessary. FlushFileBuffers(), the equivalent of sync() or
-    // fsync() on Unix, does a low-level flush to the disk, and we
-    // don't expose an API for this.
+    // Windows native mode; flushing is unnecessary.
     return true;
 }
 
 /*
     \internal
+    \since 5.1
+*/
+bool QFSFileEnginePrivate::nativeSyncToDisk()
+{
+    if (fh || fd != -1) {
+        // stdlib / stdio mode. No API available.
+        return false;
+    }
+    return FlushFileBuffers(fileHandle);
+}
+
+/*
+    \internal
 */
 qint64 QFSFileEnginePrivate::nativeSize() const
 {