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From: Juan Quintela <quintela@redhat.com>
In-Reply-To: <1396543778-22307-3-git-send-email-mst@redhat.com> (Michael
	S. Tsirkin's message of "Thu, 3 Apr 2014 19:50:31 +0300")
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	<1396543778-22307-3-git-send-email-mst@redhat.com>
Date: Fri, 04 Apr 2014 11:41:36 +0200
Message-ID: <87txa98m9b.fsf@elfo.mitica>
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Subject: Re: [Qemu-devel] [PATCH v5 02/24] vmstate: add VMS_MUST_EXIST
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>, qemu-devel@nongnu.org, Fam Zheng <famz@redhat.com>, Igor Mitsyanko <i.mitsyanko@gmail.com>, mdroth@linux.vnet.ibm.com, qemu-stable@nongnu.org, Orit Wasserman <owasserm@redhat.com>, Amit Shah <amit.shah@redhat.com>, dgilbert@redhat.com

"Michael S. Tsirkin" <mst@redhat.com> wrote:
> Can be used to verify a required field exists or validate
> state in some other way.
>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>


What should this do?

We can change the semantics of ->field_exist() to add this functionality
if needed, no?

> ---
>  include/migration/vmstate.h |  1 +
>  vmstate.c                   | 10 ++++++++++
>  2 files changed, 11 insertions(+)
>
> diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
> index e7e1705..de970ab 100644
> --- a/include/migration/vmstate.h
> +++ b/include/migration/vmstate.h
> @@ -100,6 +100,7 @@ enum VMStateFlags {
>      VMS_MULTIPLY         = 0x200,  /* multiply "size" field by field_size */
>      VMS_VARRAY_UINT8     = 0x400,  /* Array with size in uint8_t field*/
>      VMS_VARRAY_UINT32    = 0x800,  /* Array with size in uint32_t field*/
> +    VMS_MUST_EXIST       = 0x1000, /* Field must exist in input */
>  };
>  
>  typedef struct {
> diff --git a/vmstate.c b/vmstate.c
> index dd6f834..f019228 100644
> --- a/vmstate.c
> +++ b/vmstate.c
> @@ -102,6 +102,10 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
>                      return ret;
>                  }
>              }
> +        } else if (field->flags & VMS_MUST_EXIST) {
> +            fprintf(stderr, "Input validation failed: %s/%s\n",
> +                    vmsd->name, field->name);
> +            return -1;
>          }
>          field++;
>      }
> @@ -142,6 +146,12 @@ void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
>                      field->info->put(f, addr, size);
>                  }
>              }
> +        } else {
> +            if (field->flags & VMS_MUST_EXIST) {
> +                fprintf(stderr, "Output state validation failed: %s/%s\n",
> +                        vmsd->name, field->name);
> +                assert(!(field->flags & VMS_MUST_EXIST));
> +            }
>          }
>          field++;
>      }