networkGetDHCPLeases: Don't always report error if unable to read leases file

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

Posted by Michal Privoznik 7 years, 3 months ago

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@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);
+        } else {
+            rv = 0;
+        }
         goto error;
     }
 
-- 
2.16.4

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

Posted by Erik Skultety 7 years, 3 months ago

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@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@redhat.com>

> +        } else {
> +            rv = 0;
> +        }
>          goto error;
>      }
>
> --
> 2.16.4
>
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Re: [libvirt] [PATCH] networkGetDHCPLeases: Don't always report error if unable to read leases file

Posted by Michal Privoznik 7 years, 3 months ago

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@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@redhat.com>

Pushed, thanks.

Michal

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