The completion of the child process can take place asynchronously or in
one of the waitFor...() functions. In both cases, we used the same
handler (_q_processDied()), which caused several problems:
a. technically, waitForReadyRead() should have taken into account the
result of the calls to _q_canRead...() slots inside the
_q_processDied() function:
- the user calls waitForReadyRead();
- forkfd descriptor becomes signaled, while a grandchild
process is still alive;
- as readyRead() signal has not been emitted, _q_processDied()
is called;
- the grandchild process writes to stdout pipe;
- now data arrives, and _q_processDied() will collect it, but
won't report it.
b. we had a bug with recursions on Unix:
- death notification comes asynchronously;
- waitForDeadChild() closes forkfd;
- _q_canRead...() emits readyRead();
- a slot connected to readyRead() calls waitForFinished();
- waitForFinished() hangs (forkfd == -1).
c. for blocking functions, drainOutputPipes() was called twice on
Windows.
By introducing a new processFinished() function, we leave the read
operations in the _q_processDied() slot, while the process completion
code is guaranteed to run only once.
Change-Id: I5f9d09bc68a058169de4d9e490b48fc0b35e94cd
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
6a6d12ea4b