On 12.02.2016 14:17, Erik Skultety wrote:
> On 10/02/16 17:28, Michal Privoznik wrote:
>> The way we usually write functions is that we start the work and
>> if something goes bad we goto cleanup and roll back there. Or
>> just free resources that are no longer needed. Do the same here.
>>
>> Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx>
>> ---
>> tools/virsh-volume.c | 24 ++++++++++++------------
>> 1 file changed, 12 insertions(+), 12 deletions(-)
>>
>> diff --git a/tools/virsh-volume.c b/tools/virsh-volume.c
>> index 35f0cbd..569f555 100644
>> --- a/tools/virsh-volume.c
>> +++ b/tools/virsh-volume.c
>> @@ -211,14 +211,15 @@ static bool
>> cmdVolCreateAs(vshControl *ctl, const vshCmd *cmd)
>> {
>> virStoragePoolPtr pool;
>> - virStorageVolPtr vol;
>> - char *xml;
>> + virStorageVolPtr vol = NULL;
>> + char *xml = NULL;
>> const char *name, *capacityStr = NULL, *allocationStr = NULL, *format = NULL;
>> const char *snapshotStrVol = NULL, *snapshotStrFormat = NULL;
>> unsigned long long capacity, allocation = 0;
>> virBuffer buf = VIR_BUFFER_INITIALIZER;
>> unsigned long flags = 0;
>> virshControlPtr priv = ctl->privData;
>> + bool ret = false;
>>
>> if (vshCommandOptBool(cmd, "prealloc-metadata"))
>> flags |= VIR_STORAGE_VOL_CREATE_PREALLOC_METADATA;
>> @@ -335,23 +336,22 @@ cmdVolCreateAs(vshControl *ctl, const vshCmd *cmd)
>> goto cleanup;
>> }
>> xml = virBufferContentAndReset(&buf);
>> - vol = virStorageVolCreateXML(pool, xml, flags);
>> - VIR_FREE(xml);
>> - virStoragePoolFree(pool);
>>
>> - if (vol != NULL) {
>> - vshPrint(ctl, _("Vol %s created\n"), name);
>> - virStorageVolFree(vol);
>> - return true;
>> - } else {
>> + if (!(vol = virStorageVolCreateXML(pool, xml, flags))) {
>> vshError(ctl, _("Failed to create vol %s"), name);
>> - return false;
>> + goto cleanup;
>> }
>>
>> + vshPrint(ctl, _("Vol %s created\n"), name);
>> + ret = true;
>> +
>> cleanup:
>> virBufferFreeAndReset(&buf);
>> + if (vol)
>
> Looking at virStorageVolFree, this bit ^^^ is really unnecessary to have
> here. I mean, yeah, it can return -1, but we never test for it.
> In fact, it can return -1 only if the pointer is NULL or the object is
> of a different instance than it should be, and in your case, you don't
> care about the former and that kind of check certainly wouldn't avoid
> trying to unref the latter. The sad thing is, we're inconsistent in
> usage of this throughout modules.
I think we are consistent. I wasn't able to find any occurrence where we
could call virStorageVolFree() over NULL. Secondly, it's important to
check it so that we don't poison logs. For instance, if something goes
wrong, we print an error message. But there's no point in printing
another one just because we are lazy to put a check there. Yes, we are
not checking for the return value of virStorageVolFree() itself, but we
never do that and I bet you couldn't find anyone really doing that.
That's why I think we are safe to teach our public free APIs to take
NULL, but that's a different cup of tea.
Long story short, I think we should stay consistent and have the check
there.
Michal
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