Re: [Qemu-devel] [PATCH] Acceptance tests: add Linux initrd checking test

[Eduardo Habkost]

On Thu, Oct 18, 2018 at 05:45:56PM -0400, Cleber Rosa wrote:
> 
> 
> On 10/18/18 12:20 PM, Wainer dos Santos Moschetta wrote:
> > QEMU used to exits with a not accurate error message when
> > an initrd >= 2GB was passed. That was fixed on patch:
> > 
> >     commit f3839fda5771596152b75dd1e1a6d050e6e6e380
> >     Author: Li Zhijian <address@hidden>
> >     Date:   Thu Sep 13 18:07:13 2018 +0800
> > 
> >             change get_image_size return type to int64_t
> > 
> > This change adds a regression test for that fix. It starts
> > QEMU with a 2GB dummy initrd, and check it evaluates the file
> > size correctly and prints accurate message.
> > 
> > Signed-off-by: Wainer dos Santos Moschetta <address@hidden>
> > ---
> >  tests/acceptance/linux_initrd.py | 47 ++++++++++++++++++++++++++++++++
> >  1 file changed, 47 insertions(+)
> >  create mode 100644 tests/acceptance/linux_initrd.py
> > 
> > diff --git a/tests/acceptance/linux_initrd.py 
> > b/tests/acceptance/linux_initrd.py
> > new file mode 100644
> > index 0000000000..7d9e5862cd
> > --- /dev/null
> > +++ b/tests/acceptance/linux_initrd.py
> > @@ -0,0 +1,47 @@
> > +# Linux initrd acceptance test.
> > +#
> > +# Copyright (c) 2018 Red Hat, Inc.
> > +#
> > +# Author:
> > +#  Wainer dos Santos Moschetta <address@hidden>
> > +#
> > +# This work is licensed under the terms of the GNU GPL, version 2 or
> > +# later.  See the COPYING file in the top-level directory.
> > +
> > +import tempfile
> > +
> > +from avocado_qemu import Test
> > +from avocado.utils.process import run
> > +
> > +
> > +class LinuxInitrd(Test):
> > +    """
> > +    Checks QEMU evaluates correctly the initrd file passed as -initrd 
> > option.
> > +
> > +    :avocado: enable
> > +    :avocado: tags=x86_64
> > +    """
> > +
> > +    timeout = 60
> > +
> > +    def test_with_2GB_file_should_exit_error_msg(self):
> > +        """
> > +        Pretends to boot QEMU with an initrd file with size of 2GB
> > +        and expect it exits with error message.
> > +        Regression test for bug fixed on commit f3839fda5771596152.
> > +        """
> > +        kernel_url = ('https://mirrors.kernel.org/fedora/releases/28/'
> > +                      'Everything/x86_64/os/images/pxeboot/vmlinuz')
> > +        kernel_hash = '238e083e114c48200f80d889f7e32eeb2793e02a'
> > +        kernel_path = self.fetch_asset(kernel_url, asset_hash=kernel_hash)
> > +
> > +        with tempfile.NamedTemporaryFile() as initrd:
> > +            initrd.seek(2048*(1024**2) -1)
> 
> It's a style issue, but I'd go with spaces between operators:
> 
>         initrd.seek(2048 * (1024 ** 2) - 1)
> 
> One other possibility that may improve code readability is:
> 
>         from avocado.utils.data_structures import DataSize
>         initrd.seek(DataSize('2G').b - 1)
> 

I'd agree if "2G" weren't ambiguous (I would expect it to mean
2,000,000,000, not 1,073,741,824).

I can live with the ambiguity of 2GB in the commit message, class
name, and docstring.  But having to look for the
avocado.utils.data_structures.DataSize documentation to find out
what's the file size makes the code less readable to me.


> Or finally, just set a "max_size" variable to the 2GB literal value.
> 
> > +            initrd.write(b'\0')
> > +            initrd.flush()
> > +            cmd = "%s -kernel %s -initrd %s" % (self.qemu_bin, kernel_path,
> > +                                                initrd.name)
> > +            res = run(cmd, ignore_status=True)
> > +            self.assertNotEqual(res.exit_status, 0)

I would prefer to ensure exit code is 1.  We don't want the test
to pass if QEMU crashed with a signal, for example.


> > +            expected_msg = r'.*initrd is too large.*max: \d+, need \d+.*'
> 
> I'd be a bit more assertive here and do something like:
> 
>       expected_msg = r'.*initrd is too large.*max: \d+, need %d\)' %
> max_size
> 
> And if "134053887" (which appears in "max"), is a QEMU constant, that
> can be added there as well.

I was going to suggest the opposite: just checking if the error
message contains "initrd is too large".  If we ensure the exit
status is 1, the exact format of the error message isn't very
important.

-- 
Eduardo