qt-bugs@ issue : N84155

applied: yes

author: dfaure

Fix datastream<<qint64 code to actually write to the stream, not read from it (!), in 3-1-compat mode.

    qint64 value = 0x1234567887654321LL;

    QByteArray data;

    QDataStream arg( &data, QIODevice::WriteOnly );

    arg.setVersion( QDataStream::Qt_3_1 );

    arg << value;

Without the patch, this fails with ""QIODevice::read called on a WriteOnly device".

Index: qdatastream.cpp

===================================================================

--- src/corelib/io/qdatastream.cpp.orig	(revision 452002)

+++ src/corelib/io/qdatastream.cpp	(working copy)

@@ -985,8 +985,9 @@ QDataStream &QDataStream::operator<<(qin

 {

     CHECK_STREAM_PRECOND(*this)

     if (version() < 6) {

-        quint32 i1, i2;

-        *this >> i2 >> i1;

+        quint32 i1 = i >> 32;

+        quint32 i2 = i & 0xFFFFFFFF;

+        *this << i2 << i1;

         i = ((quint64)i1 << 32) + i2;

     } else if (noswap) {                        // no conversion needed

         dev->write((char *)&i, sizeof(qint64));