Re: [Qemu-devel] [PATCH 7/8] qtest/ahci: add qcow2 support to ahci-test

[John Snow]

On 02/25/2015 10:27 AM, Stefan Hajnoczi wrote:
> On Thu, Feb 19, 2015 at 05:30:02PM -0500, John Snow wrote:
> > diff --git a/tests/libqos/libqos.c b/tests/libqos/libqos.c
> > index bc8beb2..3577401 100644
> > --- a/tests/libqos/libqos.c
> > +++ b/tests/libqos/libqos.c
> > @@ -61,3 +61,33 @@ void qtest_shutdown(QOSState *qs)
> >       qtest_quit(qs->qts);
> >       g_free(qs);
> >   }
> > +
> > +int mkqcow2(const char *file, unsigned size_mb)
> > +{
> > +    pid_t pid;
> > +    int rc;
> > +    char buff[32];
> > +
> > +    snprintf(buff, 32, "%uM", size_mb);
> > +
> > +    pid = fork();
> > +    switch (pid) {
> > +    case -1:
> > +        perror("fork failed");
> > +        return -1;
> > +    case 0:
> > +        close(fileno(stdout));
> > +        rc = open("/dev/null", O_WRONLY);
> > +        g_assert_cmpint(rc, ==, fileno(stdout));
> > +        execl("./qemu-img", "qemu-img", "create", "-f", "qcow2",
> > +              file, buff, NULL);
>
> Where is the current working directory set?

Nowhere in-program. We assume you are running this via `make check` 
which further assumes that qemu-img is in your build tree. We actually 
never set an explicit path for where the QEMU binary is either: it's set 
to e.g.:

QTEST_QEMU_BINARY=x86_64-softmmu/qemu-system-x86_64
and then executed via execlp("exec QTEST_QEMU_BINARY", ...)

This patch pulls a similar shortcut.

The Makefile blob doesn't actually appear to really ever explicitly set 
a path for where the binaries should be; qemu-img is not defined to be 
in any sort of path, so we can assume that all paths are relative to the 
Makefile.

What I will do is set QTEST_QEMU_IMG to at least match the direct name 
of the QEMU_IMG we generated, so it will have $(EXESUF) attached to it, 
for instance.

> Will this work for both in-tree and out-of-tree builds?

Yes. I usually run out of tree, but it works fine in-tree too. As long 
as relative to the Makefile ./qemu-img$(EXESUF) exists, you will be fine.

If you decide to run this outside of make check, you can always set 
QTEST_QEMU_IMG yourself.

> BTW, glib abstracts process spawning, maybe all this can be done in a
> single function call:
> https://developer.gnome.org/glib/stable/glib-Spawning-Processes.html#g-spawn-sync

OK, I've implemented it with this call instead. Will send a V2.

> > +        perror("execl failed");
> > +        exit(-1);
>
> EXIT_FAILURE is provided by the C standard for returning failure.  (-1
> is confusing because the shell exit code value cannot be negative.)
>
> > +    default:
> > +        wait(&rc);
> > +        g_assert_cmpint(rc, ==, 0);
> > +        return rc;
> > +    }
> > +
> > +    g_assert_not_reached();
> > +}
> > diff --git a/tests/libqos/libqos.h b/tests/libqos/libqos.h
> > index 612d41e..5abd2bd 100644
> > --- a/tests/libqos/libqos.h
> > +++ b/tests/libqos/libqos.h
> > @@ -19,6 +19,7 @@ typedef struct QOSState {
> >   QOSState *qtest_vboot(QOSOps *ops, const char *cmdline_fmt, va_list ap);
> >   QOSState *qtest_boot(QOSOps *ops, const char *cmdline_fmt, ...);
> >   void qtest_shutdown(QOSState *qs);
> > +int mkqcow2(const char *file, unsigned size_mb);
> >
> >   static inline uint64_t qmalloc(QOSState *q, size_t bytes)
> >   {
> > --
> > 1.9.3