Re: [Qemu-devel] [PATCH] tests/bios-tables-test: Compiler warning fix

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Daniel P. Berrange (berrange@redhat.com) wrote:
> On Thu, Jul 20, 2017 at 05:35:36PM +0100, Dr. David Alan Gilbert (git) wrote:
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > 
> > gcc 7.1.1 in fedora 26 moans about the:
> >    tables = g_new0(uint32_t, tables_nr)
> > 
> > because it can't convince itself that tables_nr is positive.
> > This is fallout from g_assert_cmpint no longer necessarily being
> > no-return;  replace it with a plain g_assert.
> > 
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > ---
> >  tests/bios-tables-test.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/tests/bios-tables-test.c b/tests/bios-tables-test.c
> > index 63da978f0b..564da45f65 100644
> > --- a/tests/bios-tables-test.c
> > +++ b/tests/bios-tables-test.c
> > @@ -108,7 +108,7 @@ static void test_acpi_rsdt_table(test_data *data)
> >      /* compute the table entries in rsdt */
> >      tables_nr = (rsdt_table->length - sizeof(AcpiRsdtDescriptorRev1)) /
> >                  sizeof(uint32_t);
> > -    g_assert_cmpint(tables_nr, >, 0);
> > +    g_assert(tables_nr > 0);
> 
> IMHO your original patch was better - rsdt_table->length is an
> uint32_t, and sizeof() evaluates to size_t, but we're assigning
> to a local  tables_nr that is a signed int. So tables_nr would
> be better declared as size_t.  That would mean the assert can
> just be removed entirely, or replaced by an assert that
> rsdt_table->length > sizeof(AcpiRsdtDescriptorRev1) if we're
> concerned about that

Given that assert was there I'd assumed Marcel was explicitly checking
for that case, so my original hack of just making it a uint or size_t
didn't seem safe.

Checking that rsdt_table->length > sizeof(AcpiRsdtDescriptorRev1)
probably is safer; although this is only a sanity assert in a test
case, not dealing with user data, so I just made the minimal change.

Dave

> 
> Regards,
> Daniel
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--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK