Re: [PATCH v2 3/6] qemu-option: restrict qemu_opts_set to merge-lists QemuOpts

[Markus Armbruster]

Paolo Bonzini <pbonzini@redhat.com> writes:

> qemu_opts_set is used to create default network backends and to
> parse sugar options -kernel, -initrd, -append, -bios and -dtb.
> Switch the former to qemu_opts_parse, so that qemu_opts_set
> is now only used on merge-lists QemuOptsList (for which it makes
> the most sense indeed)... except in the testcase, which is
> changed to use a merge-list QemuOptsList.
>
> With this change we can remove the id parameter.  With the
> parameter always NULL, we know that qemu_opts_create cannot fail
> and can pass &error_abort to it.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  include/qemu/option.h  |  3 +--
>  softmmu/vl.c           | 19 +++++++------------
>  tests/test-qemu-opts.c | 24 +++++++++++++++++++++---
>  util/qemu-option.c     |  9 +++------
>  4 files changed, 32 insertions(+), 23 deletions(-)
>
> diff --git a/include/qemu/option.h b/include/qemu/option.h
> index ac69352e0e..f73e0dc7d9 100644
> --- a/include/qemu/option.h
> +++ b/include/qemu/option.h
> @@ -119,8 +119,7 @@ QemuOpts *qemu_opts_create(QemuOptsList *list, const char 
> *id,
>                             int fail_if_exists, Error **errp);
>  void qemu_opts_reset(QemuOptsList *list);
>  void qemu_opts_loc_restore(QemuOpts *opts);
> -bool qemu_opts_set(QemuOptsList *list, const char *id,
> -                   const char *name, const char *value, Error **errp);
> +bool qemu_opts_set(QemuOptsList *list, const char *name, const char *value, 
> Error **errp);

Long line.  Please break before Error.

>  const char *qemu_opts_id(QemuOpts *opts);
>  void qemu_opts_set_id(QemuOpts *opts, char *id);
>  void qemu_opts_del(QemuOpts *opts);
> diff --git a/softmmu/vl.c b/softmmu/vl.c
> index a71164494e..65607fe55e 100644
> --- a/softmmu/vl.c
> +++ b/softmmu/vl.c
> @@ -3107,20 +3107,16 @@ void qemu_init(int argc, char **argv, char **envp)
>                  }
>                  break;
>              case QEMU_OPTION_kernel:
> -                qemu_opts_set(qemu_find_opts("machine"), NULL, "kernel", 
> optarg,
> -                              &error_abort);
> +                qemu_opts_set(qemu_find_opts("machine"), "kernel", optarg, 
> &error_abort);
>                  break;
>              case QEMU_OPTION_initrd:
> -                qemu_opts_set(qemu_find_opts("machine"), NULL, "initrd", 
> optarg,
> -                              &error_abort);
> +                qemu_opts_set(qemu_find_opts("machine"), "initrd", optarg, 
> &error_abort);
>                  break;
>              case QEMU_OPTION_append:
> -                qemu_opts_set(qemu_find_opts("machine"), NULL, "append", 
> optarg,
> -                              &error_abort);
> +                qemu_opts_set(qemu_find_opts("machine"), "append", optarg, 
> &error_abort);
>                  break;
>              case QEMU_OPTION_dtb:
> -                qemu_opts_set(qemu_find_opts("machine"), NULL, "dtb", optarg,
> -                              &error_abort);
> +                qemu_opts_set(qemu_find_opts("machine"), "dtb", optarg, 
> &error_abort);
>                  break;
>              case QEMU_OPTION_cdrom:
>                  drive_add(IF_DEFAULT, 2, optarg, CDROM_OPTS);
> @@ -3230,8 +3226,7 @@ void qemu_init(int argc, char **argv, char **envp)
>                  }
>                  break;
>              case QEMU_OPTION_bios:
> -                qemu_opts_set(qemu_find_opts("machine"), NULL, "firmware", 
> optarg,
> -                              &error_abort);
> +                qemu_opts_set(qemu_find_opts("machine"), "firmware", optarg, 
> &error_abort);
>                  break;
>              case QEMU_OPTION_singlestep:
>                  singlestep = 1;

Long lines.  Please keep the line breaks.

> @@ -4258,9 +4253,9 @@ void qemu_init(int argc, char **argv, char **envp)
>  
>      if (default_net) {
>          QemuOptsList *net = qemu_find_opts("net");
> -        qemu_opts_set(net, NULL, "type", "nic", &error_abort);
> +        qemu_opts_parse(net, "nic", true, &error_abort);
>  #ifdef CONFIG_SLIRP
> -        qemu_opts_set(net, NULL, "type", "user", &error_abort);
> +        qemu_opts_parse(net, "user", true, &error_abort);
>  #endif
>      }
>  

Looks safe to me, but I don't quite get why you switch to
qemu_opts_parse().  The commit message explains it is "so that
qemu_opts_set is now only used on merge-lists QemuOptsList (for which it
makes the most sense indeed)..."  Is there anything wrong with using ot
on non-merge-lists QemuOptsList?

Am I missing something?

> diff --git a/tests/test-qemu-opts.c b/tests/test-qemu-opts.c
> index 297ffe79dd..322b32871b 100644
> --- a/tests/test-qemu-opts.c
> +++ b/tests/test-qemu-opts.c
> @@ -84,11 +84,25 @@ static QemuOptsList opts_list_03 = {
>      },
>  };
>  
> +static QemuOptsList opts_list_04 = {
> +    .name = "opts_list_04",
> +    .head = QTAILQ_HEAD_INITIALIZER(opts_list_04.head),
> +    .merge_lists = true,
> +    .desc = {
> +        {
> +            .name = "str3",
> +            .type = QEMU_OPT_STRING,
> +        },
> +        { /* end of list */ }
> +    },
> +};
> +
>  static void register_opts(void)
>  {
>      qemu_add_opts(&opts_list_01);
>      qemu_add_opts(&opts_list_02);
>      qemu_add_opts(&opts_list_03);
> +    qemu_add_opts(&opts_list_04);
>  }
>  
>  static void test_find_unknown_opts(void)
> @@ -402,17 +416,21 @@ static void test_qemu_opts_set(void)
>      QemuOpts *opts;
>      const char *opt;
>  
> -    list = qemu_find_opts("opts_list_01");
> +    list = qemu_find_opts("opts_list_04");
>      g_assert(list != NULL);
>      g_assert(QTAILQ_EMPTY(&list->head));
> -    g_assert_cmpstr(list->name, ==, "opts_list_01");
> +    g_assert_cmpstr(list->name, ==, "opts_list_04");
>  
>      /* should not find anything at this point */
>      opts = qemu_opts_find(list, NULL);
>      g_assert(opts == NULL);
>  
>      /* implicitly create opts and set str3 value */
> -    qemu_opts_set(list, NULL, "str3", "value", &error_abort);
> +    qemu_opts_set(list, "str3", "first_value", &error_abort);


This part the commit message mentions.

> +    g_assert(!QTAILQ_EMPTY(&list->head));
> +
> +    /* set it again */
> +    qemu_opts_set(list, "str3", "value", &error_abort);
>      g_assert(!QTAILQ_EMPTY(&list->head));

This one not.

What are you trying to accomplish?

>  
>      /* get the just created opts */
> diff --git a/util/qemu-option.c b/util/qemu-option.c
> index 59be4f9d21..c88e159f18 100644
> --- a/util/qemu-option.c
> +++ b/util/qemu-option.c
> @@ -665,15 +665,12 @@ void qemu_opts_loc_restore(QemuOpts *opts)
>      loc_restore(&opts->loc);
>  }
>  
> -bool qemu_opts_set(QemuOptsList *list, const char *id,
> -                   const char *name, const char *value, Error **errp)
> +bool qemu_opts_set(QemuOptsList *list, const char *name, const char *value, 
> Error **errp)

Long line.  Please break before Error.

>  {
>      QemuOpts *opts;
>  
> -    opts = qemu_opts_create(list, id, 1, errp);
> -    if (!opts) {
> -        return false;
> -    }
> +    assert(list->merge_lists);
> +    opts = qemu_opts_create(list, NULL, 0, &error_abort);
>      return qemu_opt_set(opts, name, value, errp);
>  }

Yes, qemu_opts_create() can fail only if its second paramter is
non-null, or its thirs paramter is non-zero.

I can see quite a few such calls.  Could be simplified with a wrapper
that takes just the first parameter and can't fail.  Not now.

Just enough confusion on my part to withhold my R-by for now.