[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH 2/3] qtest: make QEMU our direct child process
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH 2/3] qtest: make QEMU our direct child process |
Date: |
Tue, 18 Feb 2014 10:00:36 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Mon, Feb 17, 2014 at 05:44:55PM +0100, Markus Armbruster wrote:
> Stefan Hajnoczi <address@hidden> writes:
>
> > qtest_init() cannot use exec*p() to launch QEMU since the exec*p()
> > functions take an argument array while qtest_init() takes char
> > *extra_args. Therefore we execute /bin/sh -c <command-line> and let the
> > shell parse the argument string.
> >
> > This left /bin/sh as our child process and our child's child was QEMU.
> > We still want QEMU's pid so the -pidfile option was used to let QEMU
> > report its pid.
> >
> > The pidfile needs to be unlinked when the test case exits or fails. In
> > other words, the pidfile creates a new problem for us!
> >
> > Simplify all this using the shell 'exec' command. It allows us to
> > replace the /bin/sh process with QEMU. Then we no longer need to use
> > -pidfile because we already know our fork child's pid.
> >
> > Note: Yes, it seems silly to exec /bin/sh when we could just exec QEMU
> > directly. But remember qtest_init() takes a single char *extra_args
> > command-line fragment instead of a real argv[] array, so we need
> > /bin/sh's argument parsing behavior.
>
> Sounds like a design mistake to me.
I wouldn't call char *extra_args a mistake because strings are still
simpler to manipulate in C than char *argv[] arrays. So we write less
code in test cases and libqtest.c at the expense of a roundabout way to
spawn the process.
Stefan
- [Qemu-devel] [PATCH 0/3] qtest: avoid pidfile and QEMU process leaks, Stefan Hajnoczi, 2014/02/17
- [Qemu-devel] [PATCH 3/3] qtest: kill QEMU process on g_assert() failure, Stefan Hajnoczi, 2014/02/17
- Re: [Qemu-devel] [PATCH 3/3] qtest: kill QEMU process on g_assert() failure, Paolo Bonzini, 2014/02/17
- Re: [Qemu-devel] [PATCH 3/3] qtest: kill QEMU process on g_assert() failure, Markus Armbruster, 2014/02/17
- Re: [Qemu-devel] [PATCH 3/3] qtest: kill QEMU process on g_assert() failure, Stefan Hajnoczi, 2014/02/18
- Re: [Qemu-devel] [PATCH 3/3] qtest: kill QEMU process on g_assert() failure, Markus Armbruster, 2014/02/18
- Re: [Qemu-devel] [PATCH 3/3] qtest: kill QEMU process on g_assert() failure, Paolo Bonzini, 2014/02/18
- Re: [Qemu-devel] [PATCH 3/3] qtest: kill QEMU process on g_assert() failure, Markus Armbruster, 2014/02/18
- Re: [Qemu-devel] [PATCH 3/3] qtest: kill QEMU process on g_assert() failure, Stefan Hajnoczi, 2014/02/18
- Re: [Qemu-devel] [PATCH 3/3] qtest: kill QEMU process on g_assert() failure, Paolo Bonzini, 2014/02/18