[libvirt] [PATCH v2] test_driver: implement virDomainGetDiskErrors

[Michal Privoznik]

On 5/13/19 1:26 AM, Ilias Stamatis wrote:
> Return the number of disks present in the configuration of the test
> domain when called with @errors as NULL and @maxerrors as 0.
> 
> Otherwise report an error for every second disk, assigning available
> error codes in a cyclic order.
> 
> Signed-off-by: Ilias Stamatis <stamatis.iliass at gmail.com>
> ---
>   src/test/test_driver.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 42 insertions(+)
> 
> diff --git a/src/test/test_driver.c b/src/test/test_driver.c
> index a06d1fc402..527c2f5d3b 100644
> --- a/src/test/test_driver.c
> +++ b/src/test/test_driver.c
> @@ -3046,6 +3046,47 @@ static int testDomainSetAutostart(virDomainPtr domain,
>       return 0;
>   }
> 
> +static int testDomainGetDiskErrors(virDomainPtr dom,
> +                                   virDomainDiskErrorPtr errors,
> +                                   unsigned int maxerrors,
> +                                   unsigned int flags)
> +{
> +    virDomainObjPtr vm = NULL;
> +    int ret = -1;
> +    size_t i;
> +    int n = 0;
> +    int codes[] = {VIR_DOMAIN_DISK_ERROR_UNSPEC, VIR_DOMAIN_DISK_ERROR_NO_SPACE};
> +    size_t ncodes = sizeof(codes) / sizeof(codes[0]);

We have ARRAY_CARDINALITY() for this.
Also, there's no need to create @codes array as we'll see later.

> +
> +    virCheckFlags(0, -1);
> +
> +    if (!(vm = testDomObjFromDomain(dom)))
> +        goto cleanup;
> +
> +    if (virDomainObjCheckActive(vm) < 0)
> +        goto cleanup;
> +
> +    if (!errors) {
> +        ret = vm->def->ndisks;

Tiny nitpick, we tend to put the longer body first, which in this case 
is the else branch.

> +    } else {
> +        for (i = 1; i < vm->def->ndisks && n < maxerrors; i += 2) {
> +            if (VIR_STRDUP(errors[n].disk, vm->def->disks[i]->dst) < 0)
> +                goto cleanup;
> +            errors[n].error = codes[n % ncodes];

This can be simplified. This enum in question is guaranteed to have 
continuous items and _LAST to be the last item. Hence, this can be 
rewritten as:

errors[i].error = (i % (VIR_DOMAIN_DISK_ERROR_LAST - 1)) + 1;

But if we want to simplify it a little bit more (so that 
VIR_DOMAIN_DISK_ERROR_NONE is possible too) we can do it like this:

errors[i].error = i % VIR_DOMAIN_DISK_ERROR_LAST;

This immediatelly drops @codes, @ncodes and @n variables.
Also, there's MIN() macro ;-)
Yeah, libvirt has a lot of marcos and helpers and it's not obvious at 
the first glance, but I guess that's like so with every bigger project, 
isn't it?

> +            n++;
> +        }
> +        ret = n;
> +    }
> +
> + cleanup:
> +    virDomainObjEndAPI(&vm);
> +    if (ret < 0) {
> +        for (i = 0; i < n; i++)
> +            VIR_FREE(errors[i].disk);
> +    }
> +    return ret;
> +}
> +
>   static char *testDomainGetSchedulerType(virDomainPtr domain ATTRIBUTE_UNUSED,
>                                           int *nparams)
>   {
> @@ -6832,6 +6873,7 @@ static virHypervisorDriver testHypervisorDriver = {
>       .domainUndefineFlags = testDomainUndefineFlags, /* 0.9.4 */
>       .domainGetAutostart = testDomainGetAutostart, /* 0.3.2 */
>       .domainSetAutostart = testDomainSetAutostart, /* 0.3.2 */
> +    .domainGetDiskErrors = testDomainGetDiskErrors, /* 5.4.0 */
>       .domainGetSchedulerType = testDomainGetSchedulerType, /* 0.3.2 */
>       .domainGetSchedulerParameters = testDomainGetSchedulerParameters, /* 0.3.2 */
>       .domainGetSchedulerParametersFlags = testDomainGetSchedulerParametersFlags, /* 0.9.2 */


I'm cleaning the patch as outlined, ACKing and pushing.

Michal