Re: [Qemu-devel] [PATCH 2/3] qtest: make QEMU our direct child process

[Markus Armbruster]

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.

> Signed-off-by: Stefan Hajnoczi <address@hidden>

Patch looks good.