Re: [PATCH v2] libqtest: refuse QTEST_QEMU_BINARY=qemu-kvm

[Thomas Huth <thuth@redhat.com>]

On 12/04/2021 16.21, Stefan Hajnoczi wrote:
> On Mon, Apr 12, 2021 at 11:35:40AM +0200, Thomas Huth wrote:
>> On 12/04/2021 11.18, Stefan Hajnoczi wrote:
>>> Some downstreams rename the QEMU binary to "qemu-kvm". This breaks
>>> qtest_get_arch(), which attempts to parse the target architecture from
>>> the QTEST_QEMU_BINARY environment variable.
>>>
>>> Print an error instead of returning the architecture "kvm". Things fail
>>> in weird ways when the architecture string is bogus.
>>>
>>> Arguably qtests should always be run in a build directory instead of
>>> against an installed QEMU. In any case, printing a clear error when this
>>> happens is helpful.
>>>
>>> Reported-by: Qin Wang <qinwang@rehdat.com>
>>> Cc: Emanuele Giuseppe Esposito <eesposit@redhat.com>
>>> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
>>> ---
>>>    tests/qtest/libqtest.c | 10 ++++++++++
>>>    1 file changed, 10 insertions(+)
>>>
>>> diff --git a/tests/qtest/libqtest.c b/tests/qtest/libqtest.c
>>> index 71e359efcd..7caf20f56b 100644
>>> --- a/tests/qtest/libqtest.c
>>> +++ b/tests/qtest/libqtest.c
>>> @@ -910,6 +910,16 @@ const char *qtest_get_arch(void)
>>>            abort();
>>>        }
>>> +    if (!strstr(qemu, "-system-")) {
>>> +        fprintf(stderr, "QTEST_QEMU_BINARY must end with *-system-<arch> where "
>>> +                        "'arch' is the target architecture (x86_64, aarch64, "
>>> +                        "etc). If you are using qemu-kvm or another custom "
>>> +                        "name, please create a symlink like ln -s "
>>> +                        "path/to/qemu-kvm qemu-system-x86_64 and use that "
>>> +                        "instead.\n");
>>
>> The text is very long ... maybe add some \n to wrap it after 80 columns?
>> (also not sure whether we really need the second part about the symlink...
>> but I also don't mind leaving it in)
>>
>>> +        abort();
>>
>> Since this can be triggered by the user, I'd rather use exit(1) instead,
>> what do you think?
> 
> Sure, but in that case I guess the abort() call above also needs to be
> changed? It is triggered when the QTEST_QEMU_BINARY path does not
> contain a hyphen ('-') and it currently aborts.

Drat, you're right, and it was even me who added that :-/ ... if you've got 
some spare minutes, could you send a patch for that, too, please? (Otherwise 
I'll do it later)

  Thomas