[V12,2/4] Create four QemuOptsList related functions

This patch will create 4 functions, count_opts_list, qemu_opts_append,
qemu_opts_free and qemu_opts_print_help, they will be used in following
commits.

Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
---
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.

 include/qemu/option.h |  4 +++
 util/qemu-option.c    | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 85 insertions(+)

Dong Xu Wang <wdongxu@linux.vnet.ibm.com> writes:

> This patch will create 4 functions, count_opts_list, qemu_opts_append,
> qemu_opts_free and qemu_opts_print_help, they will be used in following
> commits.
>
> Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
> ---
> 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.
>
>  include/qemu/option.h |  4 +++
>  util/qemu-option.c    | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 85 insertions(+)
>
> diff --git a/include/qemu/option.h b/include/qemu/option.h
> index 394170a..c58db43 100644
> --- a/include/qemu/option.h
> +++ b/include/qemu/option.h
> @@ -156,4 +156,8 @@ int qemu_opts_print(QemuOpts *opts, void *dummy);
>  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 dbb77b9..0e42452 100644
> --- a/util/qemu-option.c
> +++ b/util/qemu-option.c
> @@ -1153,3 +1153,84 @@ 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 = 0;
> +
> +    for (i = 0; list && list->desc[i].name; i++) {

"list &&" makes it accept null argument.  See below.

> +        ;
> +    }
> +
> +    return i;
> +}
> +
> +/* Create a new QemuOptsList and make its desc to the merge of 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,
> + * merge_lists is set if first's or second's is set.

I still think we should simply assert that neither argument has
merge_lists set.  Or maybe that their merge_lists match.

> + */
> +QemuOptsList *qemu_opts_append(QemuOptsList *first,
> +                               QemuOptsList *second)
> +{
> +    size_t num_first_opts, num_second_opts;
> +    QemuOptsList *dest = NULL;
> +    int i = 0;
> +    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;
> +    dest->merge_lists = first->merge_lists || second->merge_lists;

Note: in the previous version, this function accepted null arguments.
No more.  We'll see in PATCH 3/4 whether the callers are happy with this
change.

If first and second can't be null, there's no need to make
count_opts_list() accept null argument anymore, and "list &&" there
could be dropped.

> +    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 = g_strdup(p->desc[i].name);
> +            dest->desc[index].help = g_strdup(p->desc[i].help);
> +            dest->desc[index].type = p->desc[i].type;
> +            dest->desc[index].def_value_str =
> +                g_strdup(p->desc[i].def_value_str);
> +            index++;
> +        }
> +        if ((p == first) && p && !p->desc[i].name) {

Please drop superfluous paranthesesis around p == first.

> +            p = second;
> +            i = 0;
> +        }

Not exactly squeaky clean loop control, but it should do :)

> +    }
> +    dest->desc[index].name = NULL;
> +    return dest;
> +}
> +
> +/* free a QemuOptsList, can accept NULL as arguments */
> +void qemu_opts_free(QemuOptsList *list)
> +{
> +    int i = 0;
> +
> +    for (i = 0; list && list->desc[i].name; i++) {
> +        g_free((char *)list->desc[i].name);
> +        g_free((char *)list->desc[i].help);
> +        g_free((char *)list->desc[i].def_value_str);
> +    }
> +
> +    g_free(list);
> +}
> +
> +void qemu_opts_print_help(QemuOptsList *list)
> +{
> +    int i = 0;
> +    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");
> +    }
> +}