On Monday, 14 May 2018 00:32:38 PDT alexander golks wrote:
> > int QDataStream::writeRawData(const char *s, int len)
> > {
> >
> > CHECK_STREAM_WRITE_PRECOND(-1)
> > int ret = dev->write(s, len);
> > if (ret != len)
> > q_status = WriteFailed;
> > return ret;
> >
> > }
>
> it does, partly. the write has not failed, it simply has not written all
> data.
It's a matter of perspective. As seen in this thread, in some situations
failing to write everything is an unrecoverable situation. That is the case
here: QDataStream cannot recover from a partial write.
We could loop retrying the write so long as ret > 0. This is probably
acceptable here, since the alternative is to go into WriteFailed state anyway.
Would you submit an update?
> > > otherwise, as i still don't know the "no-error" conditions, i would
> > > always
> > > need to use something like QDataStream::writeRawData, which is barely
> > > more
> > > then a QFile::write, and no other operator<< methods.
> >
> > it will tell you if there was a write failure. See above.
>
> yes, but all other operator<< methods not.
The other methods do the same:
QDataStream &QDataStream::operator<<(qint16 i)
{
CHECK_STREAM_WRITE_PRECOND(*this)
if (!noswap) {
i = qbswap(i);
}
if (dev->write((char *)&i, sizeof(qint16)) != sizeof(qint16))
q_status = WriteFailed;
return *this;
}
Inserting the loop requires a bit of refactoring to centralise the writing to
the device.
> what about something like:
>
> int QDataStream::writeRawData(const char *s, int len)
> {
> CHECK_STREAM_WRITE_PRECOND(-1)
> qint64 bytesToWrite = len;
> qint64 totalWritten = 0;
> do {
> int ret = dev->write(s + totalWritten, bytesToWrite);
> if(ret < 0)
> break;
> totalWritten += ret;
> bytesToWrite -= ret;
> } while (totalWritten < len);
> if(totalWritten != len)
> q_status = WriteFailed;
> return totalWritten;
> }
>
> and appropriate modifications for all other related methods.
Please submit via the code review system.
--
Thiago Macieira - thiago.macieira (AT) intel.com
Software Architect - Intel Open Source Technology Center
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