Jeff Cody <jc...@redhat.com> writes:
> Multiple sub-systems in QEMU may find it useful to generate IDs
> for objects that a user may reference via QMP or HMP. This patch
> presents a standardized way to do it, so that automatic ID generation
> follows the same rules.
>
> This patch enforces the following rules when generating an ID:
>
> 1.) Guarantee no collisions with a user-specified ID
> 2.) Identify the sub-system the ID belongs to
> 3.) Guarantee of uniqueness
> 4.) Spoiling predictability, to avoid creating an assumption
> of object ordering and parsing (i.e., we don't want users to think
> they can guess the next ID based on prior behavior).
>
> The scheme for this is as follows (no spaces):
>
> # subsys D RR
> Reserved char --| | | |
> Subsystem String ----| | |
> Unique number (64-bit) --| |
> Two-digit random number ---|
>
> For example, a generated node-name for the block sub-system may look
> like this:
>
> #block076
>
> The caller of id_generate() is responsible for freeing the generated
> node name string with g_free().
>
> Reviewed-by: John Snow <js...@redhat.com>
> Reviewed-by: Eric Blake <ebl...@redhat.com>
> Reviewed-by: Alberto Garcia <be...@igalia.com>
> Signed-off-by: Jeff Cody <jc...@redhat.com>
> ---
> include/qemu-common.h | 8 ++++++++
> util/id.c | 37 +++++++++++++++++++++++++++++++++++++
> 2 files changed, 45 insertions(+)
>
> diff --git a/include/qemu-common.h b/include/qemu-common.h
> index 0bd212b..2f74540 100644
> --- a/include/qemu-common.h
> +++ b/include/qemu-common.h
> @@ -246,6 +246,14 @@ int64_t qemu_strtosz_suffix_unit(const char *nptr, char
> **end,
> #define STR_OR_NULL(str) ((str) ? (str) : "null")
>
> /* id.c */
> +
> +typedef enum IdSubSystems {
> + ID_QDEV,
ID_QDEV is not used in this series. Do you intend to use it in a
followup-series? Can we reasonably expect that series will be accepted?
You could sidestep these questions by making id_generate() take a string
argument ;)
> + ID_BLOCK,
> + ID_MAX /* last element, used as array size */
> +} IdSubSystems;
> +
> +char *id_generate(IdSubSystems id);
> bool id_wellformed(const char *id);
>
> /* path.c */
[...]
