Re: [Qemu-devel] [PATCH 5/9] QemuOpts: Convert qemu_opts_foreach() to Error

[Eric Blake <eblake@redhat.com>]

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On 05/28/2015 06:21 AM, Markus Armbruster wrote:
> Retain the function value for now, to permit selective conversion of
> its callers.
> 
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---
>  block/blkdebug.c                 |  6 ++--
>  hw/core/qdev-properties-system.c |  5 +--
>  include/qemu/option.h            |  4 +--
>  include/ui/console.h             |  2 +-
>  net/net.c                        |  9 ++---
>  net/vhost-user.c                 |  4 +--
>  numa.c                           |  5 +--
>  tpm.c                            |  6 ++--
>  ui/vnc.c                         |  2 +-
>  util/qemu-config.c               |  4 +--
>  util/qemu-option.c               |  7 ++--
>  vl.c                             | 72 ++++++++++++++++++++++++----------------
>  12 files changed, 72 insertions(+), 54 deletions(-)
> 

> diff --git a/block/blkdebug.c b/block/blkdebug.c
> index 58f5105..50ef1fc 100644
> --- a/block/blkdebug.c
> +++ b/block/blkdebug.c
> @@ -219,7 +219,7 @@ struct add_rule_data {
>      Error **errp;
>  };
>  
> -static int add_rule(QemuOpts *opts, void *opaque)
> +static int add_rule(void *opaque, QemuOpts *opts, Error **errp)

> +++ b/include/qemu/option.h
> @@ -125,9 +125,9 @@ QemuOpts *qemu_opts_from_qdict(QemuOptsList *list, const QDict *qdict,
>  QDict *qemu_opts_to_qdict(QemuOpts *opts, QDict *qdict);
>  void qemu_opts_absorb_qdict(QemuOpts *opts, QDict *qdict, Error **errp);
>  
> -typedef int (*qemu_opts_loopfunc)(QemuOpts *opts, void *opaque);
> +typedef int (*qemu_opts_loopfunc)(void *opaque, QemuOpts *opts, Error **errp);

Might be nice to justify in the commit message why swapping the
arguments of the callback made sense.  But doesn't affect code
correctness, so:

Reviewed-by: Eric Blake <eblake@redhat.com>


> +++ b/util/qemu-option.c
> @@ -1047,13 +1047,14 @@ void qemu_opts_validate(QemuOpts *opts, const QemuOptDesc *desc, Error **errp)
>  }
>  
>  /**
> - * For each member of @list, call @func(member, @opaque).
> + * For each member of @list, call @func(@opaque, member, @errp).
>   * Call it with the current location temporarily set to the member's.
> + * @func() may store an Error through @errp, but must return non-zero then.
>   * When @func() returns non-zero, break the loop and return that value.
>   * Return zero when the loop completes.
>   */
>  int qemu_opts_foreach(QemuOptsList *list, qemu_opts_loopfunc func,
> -                      void *opaque)
> +                      void *opaque, Error **errp)
>  {
>      Location loc;
>      QemuOpts *opts;
> @@ -1062,7 +1063,7 @@ int qemu_opts_foreach(QemuOptsList *list, qemu_opts_loopfunc func,
>      loc_push_none(&loc);
>      QTAILQ_FOREACH(opts, &list->head, next) {
>          loc_restore(&opts->loc);
> -        rc = func(opts, opaque);
> +        rc = func(opaque, opts, errp);
>          if (rc) {
>              return rc;
>          }

Do you want to enforce that if errp is set, that rc is non-zero, to
match your contract?  Perhaps by assert(!*errp) at this point?  But if
the return value goes away later in the series in favor of only using
errp, it may be a moot question.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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