[libvirt] [PATCH] networkGetDHCPLeases: Don't always report error if unable to read leases file

[Michal Privoznik]

On 07/26/2018 10:55 AM, Erik Skultety wrote:
> On Thu, Jul 26, 2018 at 09:55:17AM +0200, Michal Privoznik wrote:
>> https://bugzilla.redhat.com/show_bug.cgi?id=1600468
>>
>> If we are unable to read leases file (no matter what the reason
>> is), we return 0 - just like if there were no leases. However,
>> because we use virFileReadAll() an error is printed into the log.
>> Note that not all networks have leases file - only those for
>> which we start dnsmasq.
>>
>> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>> ---
>>  src/network/bridge_driver.c | 21 ++++++++++++++-------
>>  1 file changed, 14 insertions(+), 7 deletions(-)
>>
>> diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c
>> index a7826e9b63..5839021caf 100644
>> --- a/src/network/bridge_driver.c
>> +++ b/src/network/bridge_driver.c
>> @@ -4235,13 +4235,20 @@ networkGetDHCPLeases(virNetworkPtr net,
>>      custom_lease_file = networkDnsmasqLeaseFileNameCustom(driver, def->bridge);
>>
>>      /* Read entire contents */
>> -    if ((custom_lease_file_len = virFileReadAll(custom_lease_file,
>> -                                                VIR_NETWORK_DHCP_LEASE_FILE_SIZE_MAX,
>> -                                                &lease_entries)) < 0) {
>> -        /* Even though src/network/leaseshelper.c guarantees the existence of
>> -         * leases file (even if no leases are present), and the control reaches
>> -         * here, instead of reporting error, return 0 leases */
>> -        rv = 0;
>> +    if ((custom_lease_file_len = virFileReadAllQuiet(custom_lease_file,
>> +                                                     VIR_NETWORK_DHCP_LEASE_FILE_SIZE_MAX,
>> +                                                     &lease_entries)) < 0) {
>> +        /* Not all networks are guaranteed to have leases file.
>> +         * Only those which run dnsmasq. Therefore, if we failed
>> +         * to read the leases file, don't report error. Return 0
>> +         * leases instead. */
>> +        if (errno != ENOENT) {
>> +            virReportSystemError(errno,
>> +                                 _("Unable to read leases file: %s"),
>> +                                 custom_lease_file);
> 
> ^This is essentially a 'single-line' body, so the curly braces could be
> dropped.

While essentially it is one line, in fact it's split into three so I
rather keep the brackets, if you don't mind.

> I'd also invert the condition, so as to comply with the guidelines and
> make the 'else' clause, in this case only optically, bigger.

Oh, for some reason I though that the rule is reversed. Huh, whatever.

> 
> Regardless:
> Reviewed-by: Erik Skultety <eskultet at redhat.com>

Pushed, thanks.

Michal