There should only be one write buffer at a time in QFile

To be sure, we should explicitly use the size of that buffer and not the
whole QRingBuffer when flushing the data.

With this change, we make violations of the one-buffer-rule explicitly
fail on flush(), but we avoid corrupting data and reading past the
buffer's end.

Reviewed-by: Markus Goetz

1 files changed, 1 insertions, 1 deletions

diff --git a/src/corelib/io/qfile.cpp b/src/corelib/io/qfile.cpp
index c9b26032ea..d4077bcb23 100644
--- a/src/corelib/io/qfile.cpp
+++ b/src/corelib/io/qfile.cpp
@@ -1339,7 +1339,7 @@ QFile::setPermissions(const QString &fileName, Permissions permissions)
 
 static inline qint64 _qfile_writeData(QAbstractFileEngine *engine, QRingBuffer *buffer)
 {
-    qint64 ret = engine->write(buffer->readPointer(), buffer->size());
+    qint64 ret = engine->write(buffer->readPointer(), buffer->nextDataBlockSize());
     if (ret > 0)
         buffer->free(ret);
     return ret;