Re: [PATCH 01/15] string_list: add string_list_duplicate

[Junio C Hamano <gitster@pobox.com>]

Stefan Beller <sbeller@google.com> writes:

> The result of git_config_get_value_multi do not seem to be stable and
> may get overwritten. Have an easy way to preserve the results of that
> query.
>
> Signed-off-by: Stefan Beller <sbeller@google.com>
> ---

This morning I reviewed a patch that adds something whose name ends
with _copy(), and this may want to follow suit.

Should strdup_strings() be a separate parameter, or should it follow
what src->strdup_strings has?

"Do not seem to be stable" does not build confidence in the code,
making it sound as if the developer is basing his work on guess not
analysis, and makes it hard to tell if this is a wrong workaround to
a valid issue (e.g. it could be "making the result stable" is what
we want in the longer term) or a valid solution to a problem that
would be common across callers of that API.

>  string-list.c | 18 ++++++++++++++++++
>  string-list.h |  2 ++
>  2 files changed, 20 insertions(+)
>
> diff --git a/string-list.c b/string-list.c
> index 2a32a3f..f981c8a 100644
> --- a/string-list.c
> +++ b/string-list.c
> @@ -7,6 +7,24 @@ void string_list_init(struct string_list *list, int strdup_strings)
>  	list->strdup_strings = strdup_strings;
>  }
>  
> +struct string_list *string_list_duplicate(const struct string_list *src,
> +					  int strdup_strings)
> +{
> +	struct string_list *list;
> +	struct string_list_item *item;
> +
> +	if (!src)
> +		return NULL;
> +
> +	list = xmalloc(sizeof(*list));
> +	string_list_init(list, strdup_strings);
> +	for_each_string_list_item(item, src)
> +		string_list_append(list, item->string);
> +
> +	return list;
> +}
> +
> +
>  /* if there is no exact match, point to the index where the entry could be
>   * inserted */
>  static int get_entry_index(const struct string_list *list, const char *string,
> diff --git a/string-list.h b/string-list.h
> index d3809a1..1a5612f 100644
> --- a/string-list.h
> +++ b/string-list.h
> @@ -19,6 +19,8 @@ struct string_list {
>  #define STRING_LIST_INIT_DUP   { NULL, 0, 0, 1, NULL }
>  
>  void string_list_init(struct string_list *list, int strdup_strings);
> +struct string_list *string_list_duplicate(const struct string_list *src,
> +					  int strdup_strings);
>  
>  void print_string_list(const struct string_list *p, const char *text);
>  void string_list_clear(struct string_list *list, int free_util);