Re: [libvirt] [PATCH v2 04/10] virstring: Introduce virStringListRemove
On 05.12.2016 16:23, Martin Kletzander wrote:
On Mon, Dec 05, 2016 at 11:31:50AM +0100, Michal Privoznik wrote:
> Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
> ---
> src/libvirt_private.syms | 1 +
> src/util/virstring.c | 50 ++++++++++++++++++++++++++++++++++++++++++
> src/util/virstring.h | 3 +++
> tests/virstringtest.c | 56
> ++++++++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 110 insertions(+)
>
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index bc6588969..3d4da7356 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -2467,6 +2467,7 @@ virStringListGetFirstWithPrefix;
> virStringListHasString;
> virStringListJoin;
> virStringListLength;
> +virStringListRemove;
> virStringReplace;
> virStringSearch;
> virStringSortCompare;
> diff --git a/src/util/virstring.c b/src/util/virstring.c
> index 629f8ca32..96786db7f 100644
> --- a/src/util/virstring.c
> +++ b/src/util/virstring.c
> @@ -202,6 +202,56 @@ virStringListAdd(const char **strings,
> }
>
>
> +/**
> + * virStringListRemove:
> + * @strings: a NULL-terminated array of strings
> + * @newStrings: new NULL-terminated array of strings
> + * @item: string to remove
> + *
> + * Creates new strings list with all strings duplicated except
> + * for every occurrence of @item. Callers is responsible for
> + * freeing both @strings and returned list.
> + *
> + * Returns the number of items in the new list (excluding NULL
> + * anchor), -1 on error.
> + */
> +int
> +virStringListRemove(const char **strings,
> + char ***newStrings,
> + const char *item)
> +{
> + char **ret = NULL;
> + size_t i, j = 0;
> +
> + for (i = 0; strings && strings[i]; i++) {
> + if (STRNEQ(strings[i], item))
> + j++;
> + }
> +
> + if (!j) {
> + *newStrings = NULL;
> + return 0;
> + }
> +
> + if (VIR_ALLOC_N(ret, j + 1) < 0)
> + goto error;
> +
> + for (i = 0, j = 0; strings[i]; i++) {
> + if (STREQ(strings[i], item))
> + continue;
> + if (VIR_STRDUP(ret[j], strings[i]) < 0)
> + goto error;
> + j++;
> + }
> +
Instead of going twice through the list, you can just do it once and
then VIR_REALLOC_N the list.
That would have the same time complexity - I'd need to use memmove()
which iterates over the memory too. But it would have better memory
complexity. Okay, will do in v3.
Michal