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Re: [Qemu-devel] [PATCH 06/15] qga: Use return values instead of error_i
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH 06/15] qga: Use return values instead of error_is_set(errp) |
Date: |
Fri, 25 Apr 2014 12:21:22 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 |
On 04/25/2014 12:06 PM, Markus Armbruster wrote:
> Eric Blake <address@hidden> writes:
>
>> On 04/25/2014 09:05 AM, Markus Armbruster wrote:
>>> Using error_is_set(errp) to check whether a function call failed is
>>> fragile: it breaks when errp is null. I'm not aware of actual
>>> breakage, but checking return values instead when convenient is more
>>> robust and more obviously correct.
>>>
>>> handle = ga_get_fd_handle(ga_state, errp);
>>> - if (error_is_set(errp)) {
>>> - return 0;
>>> + if (handle < 0) {
>>> + return -1;
>>
>> Is this a bug fix that should be pushed separately, or at least called
>> out in the commit message as intentional?
>
> The return value is only used when no error has been set. So, it's at
> worst a latent bug.
>
>
> What about adding the following to the commit message:
>
> qga: Use return values instead of error_is_set(errp)
>
> Using error_is_set(errp) to check whether a function call failed is
> fragile: it breaks when errp is null. ga_get_fd_handle() and
> guest_file_handle_add() don't return a useful value when they fail,
> but that's just stupid. Fix that, and check them instead. As far
> as I can tell, errp can't be null there, but this is more robust and
> more obviously correct.
Works for me. I didn't spot anything else odd, so:
Series: Reviewed-by: Eric Blake <address@hidden>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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- [Qemu-devel] [PATCH 14/15] dump: Drop pointless error_is_set(), DumpState member errp, (continued)
- [Qemu-devel] [PATCH 14/15] dump: Drop pointless error_is_set(), DumpState member errp, Markus Armbruster, 2014/04/25
- [Qemu-devel] [PATCH 10/15] qapi: Clean up fragile use of error_is_set(), Markus Armbruster, 2014/04/25
- [Qemu-devel] [PATCH 11/15] qga: Clean up fragile use of error_is_set(), Markus Armbruster, 2014/04/25
- [Qemu-devel] [PATCH 09/15] tests/qapi-schema: Drop superfluous error_is_set(), Markus Armbruster, 2014/04/25
- [Qemu-devel] [PATCH 12/15] qga: Drop superfluous error_is_set(), Markus Armbruster, 2014/04/25
- [Qemu-devel] [PATCH 01/15] qmp hmp: Consistently name Error * objects err, and not errp, Markus Armbruster, 2014/04/25
- [Qemu-devel] [PATCH 13/15] qemu-option: Clean up fragile use of error_is_set(), Markus Armbruster, 2014/04/25
- [Qemu-devel] [PATCH 06/15] qga: Use return values instead of error_is_set(errp), Markus Armbruster, 2014/04/25
[Qemu-devel] [PATCH 04/15] qmp: Consistently name Error ** objects errp, and not err, Markus Armbruster, 2014/04/25
[Qemu-devel] [PATCH 03/15] qga: Consistently name Error ** objects errp, and not err, Markus Armbruster, 2014/04/25
[Qemu-devel] [PATCH 15/15] qmp: Don't use error_is_set() to suppress additional errors, Markus Armbruster, 2014/04/25
Re: [Qemu-devel] [PATCH 00/15] qmp qga: Purge error_is_set(), Eric Blake, 2014/04/25