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

[Erik Skultety]

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

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

> +        } else {
> +            rv = 0;
> +        }
>          goto error;
>      }
>
> --
> 2.16.4
>
> --
> libvir-list mailing list
> libvir-list at redhat.com
> https://www.redhat.com/mailman/listinfo/libvir-list