[systemd-devel] [PATCH 1/2] sd-bus: use terms from the D-Bus Specification a bit more

[Tom Gundersen]

I agree, it makes sense to use the D-Bus terms in the porting doc. Applied.

Thanks!

Tom

On Wed, Oct 1, 2014 at 5:11 PM, Simon McVittie
<simon.mcvittie at collabora.co.uk> wrote:
> D-Bus' type hierarchy as described in the spec is:
>
> \- basic
>    \- fixed type (u, i, etc.)
>    \- string-like type (s, o, g)
> \- container
>
> Someone seems to have referred to basic types as "simple types" at
> some point, but that term isn't defined in the D-Bus Specification,
> and seems redundant.
>
> So far I haven't renamed functions that use "trivial" in their names
> to mean "fixed type", to avoid confusion about whether a struct of
> constant length, like (iu), is a fixed type. The answer is that it is
> fixed-length, but is not a "fixed type", so I can see that something
> like bus_type_is_fixed() might be ambiguous.
> ---
>  src/libsystemd/sd-bus/PORTING-DBUS1 | 10 +++++-----
>  src/libsystemd/sd-bus/bus-type.h    |  2 ++
>  2 files changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/src/libsystemd/sd-bus/PORTING-DBUS1 b/src/libsystemd/sd-bus/PORTING-DBUS1
> index 9f0a91d..958e7b6 100644
> --- a/src/libsystemd/sd-bus/PORTING-DBUS1
> +++ b/src/libsystemd/sd-bus/PORTING-DBUS1
> @@ -156,11 +156,11 @@ multiple items. Some restrictions apply however:
>     contained in the payload, as well is immediately before framing of a
>     Gvariant, as well after as any padding bytes if there are any. The
>     padding bytes must be wholly contained in the preceding
> -   PAYLOAD_VEC/PAYLOAD_MEMFD item. You may not split up simple types
> -   nor arrays of trivial types. The latter is necessary to allow APIs
> -   to return direct pointers to linear chunks of fixed size trivial
> -   arrays. Examples: The simple types "u", "s", "t" have to be in the
> -   same payload item. The array of simple types "ay", "ai" have to be
> +   PAYLOAD_VEC/PAYLOAD_MEMFD item. You may not split up basic types
> +   nor arrays of fixed types. The latter is necessary to allow APIs
> +   to return direct pointers to linear arrays of numeric
> +   values. Examples: The basic types "u", "s", "t" have to be in the
> +   same payload item. The array of fixed types "ay", "ai" have to be
>     fully in contained in the same payload item. For an array "as" or
>     "a(si)" the only restriction however is to keep each string
>     individually in an uninterrupted item, to keep the framing of each
> diff --git a/src/libsystemd/sd-bus/bus-type.h b/src/libsystemd/sd-bus/bus-type.h
> index 2e423bb..581e8d5 100644
> --- a/src/libsystemd/sd-bus/bus-type.h
> +++ b/src/libsystemd/sd-bus/bus-type.h
> @@ -29,6 +29,8 @@
>  bool bus_type_is_valid(char c) _const_;
>  bool bus_type_is_valid_in_signature(char c) _const_;
>  bool bus_type_is_basic(char c) _const_;
> +/* "trivial" is systemd's term for what the D-Bus Specification calls
> + * a "fixed type": that is, a basic type of fixed length */
>  bool bus_type_is_trivial(char c) _const_;
>  bool bus_type_is_container(char c) _const_;
>
> --
> 2.1.1
>
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