Re: [Qemu-devel] [PATCH V15 3/6] Create four QemuOptsList related functions

[Dongxu Wang <wdongxu@linux.vnet.ibm.com>]

On 2013/5/31 5:43, Eric Blake wrote:
> On 05/30/2013 03:55 AM, Dongxu Wang wrote:
>> From: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
>>
>> This patch will create 4 functions, count_opts_list, qemu_opts_append,
>
> s/will create/creates/ - commit messages make the most sense when
> written in present tense
>
>> qemu_opts_free and qemu_opts_print_help, they will be used in following
>> commits.
>>
>
> Again, this portion...
>
>> 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.
>
> ...belongs after '---', and
>
>>
>> Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
>> Signed-off-by: Dongxu Wang <wdongxu@linux.vnet.ibm.com>
>
> your s-o-b is unusual.
>
>
>> +
>> +static size_t count_opts_list(QemuOptsList *list)
>> +{
>> +    size_t i = 0;
>> +
>> +    for (i = 0; list && list->desc[i].name; i++) {
>
> No need to initialize i to 0 in two places.
>
Okay.
>> +        ;
>> +    }
>> +
>> +    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.
>> + * Both merge_lists should not be set. Both list can be NULL.
>> + */
>> +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;
>> +    assert((!first || !first->merge_lists)
>> +        && (!second || !second->merge_lists));
>> +    QTAILQ_INIT(&dest->head);
>> +
>> +    for (i = 0; p && p->desc[i].name; i++) {
>
> Again, a double-initialization of i [1]
Okay.
>
>> +        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);
>
> Do we really have to strdup these elements, or are we guaranteed that
> the scope of the original first/second list is always larger than the
> scope of the merged list, and can thus share the existing pointer rather
> than creating copies? [2]
I think yes, will use pointer directly in next version.
>
>> +            index++;
>> +        }
>> +        if (p == first && p && !p->desc[i].name) {
>> +            p = second;
>> +            i = 0;
>> +        }
>> +    }
>> +    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++) {
>
> [1] and again for double initialization of i
>
>> +        g_free((char *)list->desc[i].name);
>> +        g_free((char *)list->desc[i].help);
>> +        g_free((char *)list->desc[i].def_value_str);
>
> [2] The fact that you have to cast away const is a sign that maybe you
> shouldn't be storing strdup'd data in these pointers in the first place.
>
>> +    }
>> +
>> +    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++) {
>
> [1] and another
>
>> +        printf("%-16s %s\n", list->desc[i].name,
>> +            list->desc[i].help ?
>> +                list->desc[i].help : "No description available");
>> +    }
>> +}
>>
>