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Re: [Qemu-devel] [PATCH for-2.4 2/2] qom: Fix invalid error check in pro
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH for-2.4 2/2] qom: Fix invalid error check in property_get_str() |
Date: |
Mon, 20 Jul 2015 09:20:22 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 |
On 07/01/2015 09:47 AM, Markus Armbruster wrote:
> When a function returns a null pointer on error and only on error, you
> can do
>
> if (!foo(foos, errp)) {
> ... handle error ...
> }
>
> instead of the more cumbersome
>
> Error *err = NULL;
>
> if (!foo(foos, &err)) {
> error_propagate(errp, err);
> ... handle error ...
> }
>
> A StringProperty's getter, however, may return null on success! We
> then fail to call visit_type_str().
>
> Screwed up in 6a146eb, v1.1.
>
> Fails tests/qom-test in my current, heavily hacked QAPI branch. No
> reproducer for master known (but I didn't look hard).
>
> Cc: Andreas Färber <address@hidden>
> Cc: Anthony Liguori <address@hidden>
> Signed-off-by: Markus Armbruster <address@hidden>
> ---
> qom/object.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
Reviewed-by: Eric Blake <address@hidden>
> diff --git a/qom/object.c b/qom/object.c
> index 6173da8..4c4df55 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -1591,14 +1591,18 @@ typedef struct StringProperty
> static void property_get_str(Object *obj, Visitor *v, void *opaque,
> const char *name, Error **errp)
> {
> + Error *err = NULL;
> StringProperty *prop = opaque;
> char *value;
>
> - value = prop->get(obj, errp);
> - if (value) {
> - visit_type_str(v, &value, name, errp);
> - g_free(value);
> + value = prop->get(obj, &err);
> + if (err) {
> + error_propagate(errp, err);
> + return;
> }
> +
> + visit_type_str(v, &value, name, errp);
> + g_free(value);
> }
>
> static void property_set_str(Object *obj, Visitor *v, void *opaque,
>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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