Simplify QFSFileEngine code: QFile does not require buffering

We still support buffering via stdio.h (FILE*), but QFSFileEngine itself
is not responsible for the buffering. Opening by file name (not FILE*
and not file descriptor) already added the Unbuffered flag.

Change-Id: I2bc52f3c7a574209b213fffd1498d4e3f78fe1bf
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/src/corelib/io/qfile.cpp b/src/corelib/io/qfile.cpp
index 6249d54f7d..c19cb92715 100644
--- a/src/corelib/io/qfile.cpp
+++ b/src/corelib/io/qfile.cpp
@@ -956,7 +956,9 @@ bool QFile::open(FILE *fh, OpenMode mode, FileHandleFlags handleFlags)
         qWarning("QFile::open: File access not specified");
         return false;
     }
-    if (d->openExternalFile(mode, fh, handleFlags)) {
+
+    // QIODevice provides the buffering, so request unbuffered file engines
+    if (d->openExternalFile(mode | Unbuffered, fh, handleFlags)) {
         QIODevice::open(mode);
         if (!(mode & Append) && !isSequential()) {
             qint64 pos = (qint64)QT_FTELL(fh);
@@ -1012,7 +1014,9 @@ bool QFile::open(int fd, OpenMode mode, FileHandleFlags handleFlags)
         qWarning("QFile::open: File access not specified");
         return false;
     }
-    if (d->openExternalFile(mode, fd, handleFlags)) {
+
+    // QIODevice provides the buffering, so request unbuffered file engines
+    if (d->openExternalFile(mode | Unbuffered, fd, handleFlags)) {
         QIODevice::open(mode);
         if (!(mode & Append) && !isSequential()) {
             qint64 pos = (qint64)QT_LSEEK(fd, QT_OFF_T(0), SEEK_CUR);