Re: [Qemu-devel] [PATCH V18 03/25] qemu-option: create four QemuOptsList related functions

[Kevin Wolf <kwolf@redhat.com>]

Am 13.08.2013 um 06:31 hat Dong Xu Wang geschrieben:
> This patch creates 4 functions, count_opts_list, qemu_opts_append,
> qemu_opts_free and qemu_opts_print_help, they are used in following
> commits.
> 
> v16->v17:
> 1) fix indentation.
> 2) fix typo.
> 
> v15->v16:
> 1) discard double-initialization.
> 2) use pointer directly, not g_strdup.
> 
> v12->v13:
> 1) simply assert that neither argument has merge_lists set.
> 2) drop superfluous paranthesesis around p == first.
> 
> v11->v12:
> 1) renmae functions.
> 2) fix loop styles and code styles.
> 3) qemu_opts_apend will not return NULL now.
> 4) merge_lists value is from arguments in qemu_opts_append.
> 
> v6->v7:
> 1) Fix typo.
> 
> v5->v6:
> 1) allocate enough space in append_opts_list function.
> 
> Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
> ---
>  include/qemu/option.h |  3 +++
>  util/qemu-option.c    | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 76 insertions(+)
> 
> diff --git a/include/qemu/option.h b/include/qemu/option.h
> index bbbdea3..3b514bb 100644
> --- a/include/qemu/option.h
> +++ b/include/qemu/option.h
> @@ -158,4 +158,7 @@ int qemu_opts_print(QemuOpts *opts);
>  int qemu_opts_foreach(QemuOptsList *list, qemu_opts_loopfunc func, void *opaque,
>                        int abort_on_failure);
>  
> +QemuOptsList *qemu_opts_append(QemuOptsList *first, QemuOptsList *second);
> +void qemu_opts_free(QemuOptsList *list);
> +void qemu_opts_print_help(QemuOptsList *list);
>  #endif
> diff --git a/util/qemu-option.c b/util/qemu-option.c
> index a3c3c17..2a5447c 100644
> --- a/util/qemu-option.c
> +++ b/util/qemu-option.c
> @@ -1201,3 +1201,76 @@ int qemu_opts_foreach(QemuOptsList *list, qemu_opts_loopfunc func, void *opaque,
>      loc_pop(&loc);
>      return rc;
>  }
> +
> +static size_t count_opts_list(QemuOptsList *list)
> +{
> +    size_t i;
> +
> +    for (i = 0; list && list->desc[i].name; i++) {
> +        ;
> +    }
> +
> +    return i;
> +}
> +
> +/* Create a new QemuOptsList with a desc of the merge of the first
> + * and second. It will allocate space for one new QemuOptsList plus
> + * enough space for QemuOptDesc in first and second QemuOptsList.
> + * First argument's QemuOptDesc members take precedence over second's.
> + * The result's name and implied_opt_name are not copied from them.
> + * Both merge_lists should not be set. Both lists can be NULL.
> + */
> +QemuOptsList *qemu_opts_append(QemuOptsList *first,
> +                               QemuOptsList *second)
> +{
> +    size_t num_first_opts, num_second_opts;
> +    QemuOptsList *dest = NULL;
> +    int i;
> +    int index = 0;
> +    QemuOptsList *p = first;
> +
> +    num_first_opts = count_opts_list(first);
> +    num_second_opts = count_opts_list(second);
> +
> +    dest = g_malloc0(sizeof(QemuOptsList)
> +        + (num_first_opts + num_second_opts + 1) * sizeof(QemuOptDesc));
> +
> +    dest->name = "append_opts_list";
> +    dest->implied_opt_name = NULL;
> +    assert((!first || !first->merge_lists)
> +           && (!second || !second->merge_lists));
> +    QTAILQ_INIT(&dest->head);
> +
> +    for (i = 0; p && p->desc[i].name; i++) {
> +        if (!find_desc_by_name(dest->desc, p->desc[i].name)) {
> +            dest->desc[index].name = p->desc[i].name;
> +            dest->desc[index].help = p->desc[i].help;
> +            dest->desc[index].type = p->desc[i].type;
> +            dest->desc[index].def_value_str =  p->desc[i].def_value_str;

Can be simplified as:

dest->desc[index] = p->desc[i];

> +            index++;
> +        }
> +        if (p == first && p && !p->desc[i].name) {
> +            p = second;
> +            i = 0;
> +        }

And then the loop body is small enough that you don't have to iterate
two arrays in one loop and confuse readers, but can use two separate
loops.

> +    }
> +    dest->desc[index].name = NULL;
> +    return dest;
> +}
> +
> +/* free a QemuOptsList, can accept NULL as arguments */
> +void qemu_opts_free(QemuOptsList *list)
> +{
> +    g_free(list);
> +}
> +
> +void qemu_opts_print_help(QemuOptsList *list)
> +{
> +    int i;
> +    printf("Supported options:\n");
> +    for (i = 0; list && list->desc[i].name; i++) {
> +        printf("%-16s %s\n", list->desc[i].name,
> +               list->desc[i].help ?
> +               list->desc[i].help : "No description available");

Is "No description available" a helpful string or should we just print
an empty string?

Kevin