[libvirt] [PATCH] util: return generic error in virCopyLastError if error is not set

[Nikolay Shirokovskiy]

On 17.05.2018 13:11, Nikolay Shirokovskiy wrote:
> virCopyLastError is intended to be used after last error is set.
> However due to virLastErrorObject failures (very unlikely through
> as thread local error is allocated on first use) we can have zero
> fields in a copy as a result. In particular code field can be set
> to VIR_ERR_OK.
> 
> In some places (qemu monitor, qemu agent and qemu migaration code
> for example) we use copy result as a flag and this leads to bugs.
> 
> Let's set copy result to generic error ("cause unknown") in this case.
> Approach is based on John Ferlan comments in [1] and [2] to initial
> attempt which fixes issue in much less generic way.
> 
> [1] https://www.redhat.com/archives/libvir-list/2018-April/msg02700.html
> [2] https://www.redhat.com/archives/libvir-list/2018-May/msg00124.html
> ---
>  src/util/virerror.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/util/virerror.c b/src/util/virerror.c
> index c000b00..9f158af 100644
> --- a/src/util/virerror.c
> +++ b/src/util/virerror.c
> @@ -343,7 +343,7 @@ virCopyLastError(virErrorPtr to)
>      if (err)
>          virCopyError(err, to);
>      else
> -        virResetError(to);
> +        virErrorGenericFailure(err);

virErrorGenericFailure(to) of course

>      return to->code;
>  }
>  
>