[Solved] QProcess pipe creation on Windows

keesvp

In porting from Qt4 to Qt5 I had problems with the named pipes. I found I had to make the following adjustments:
original:
@ hRead = CreateNamedPipe(pipeName,
PIPE_ACCESS_INBOUND | FILE_FLAG_OVERLAPPED,
dwPipeFlags,
1, // only one pipe instance
0, // output buffer size
dwPipeBufferSize, // input buffer size
0,
&secAtt);
hWrite = CreateFile(pipeName,
GENERIC_WRITE,
0,
&secAtt,
OPEN_EXISTING,
FILE_FLAG_OVERLAPPED,
NULL);
@
My version:

@ hRead = CreateNamedPipe(pipeName,
( isInputPipe ? PIPE_ACCESS_OUTBOUND : PIPE_ACCESS_INBOUND ) | FILE_FLAG_OVERLAPPED,
dwPipeFlags,
1, // only one pipe instance
dwPipeBufferSize, // output buffer size
dwPipeBufferSize, // input buffer size
0,
&secAtt);
hWrite = CreateFile(pipeName,
isInputPipe ? GENERIC_READ | FILE_WRITE_ATTRIBUTES :
GENERIC_WRITE,
0,
&secAtt,
OPEN_EXISTING,
FILE_FLAG_OVERLAPPED,
NULL);
@

Isn't it essential to have the in/out dependent mode settings???

SGaist

Hi and welcome to devnet,

It seems indeed to be strange. You should check the "bug report system":http://bugreports.qt-project.org to see whether it's something known. If not, you could open a new bug report explaining what was working and what doesn't. Providing a minimal compilable example that shows the behavior would be really great.

keesvp

Thanks.
I just filed a bug report.I couldn't find a report mentioning the same issue.
It's not simple to extract a minimal example, but I'll try.

SGaist

Can you share the link to the report ?

keesvp

Sure:
https://bugreports.qt-project.org/browse/QTBUG-35357

I realize it's terse. I'm working on an extracted sample. Problem is, this is a huge project. I'm having another issue that might be or not be related. And is in cooperation with libuv, which is complex in its own way.

SGaist

Do you know how to trigger the bad behavior ?

Just a supposition but I think you need two processes: one that you call with QProcess and your software where you use QProcess then you can establish the communication between the two. So it looks like a subdir project with two applications. Hope it helps

keesvp

Yes, that's exactly what I'm working on. I've been able to set it up like that with 2 VS-2012 projects, which I can run/debug in parallel. I need to 'skin' libuv to get something communicable.

SGaist

Great ! If I may, once you're done, convert them in one or two qmake powered project so it's not tied to VS

SGaist

Just saw that the bug has been solved, please update the thread title prepending [solved] so other forum users may know that a solutions has been found :)