Why GVariant? (Re: Starting the kdbus discussions

[Thiago Macieira]

On quinta-feira, 2 de janeiro de 2014 16:24:02, rony wrote:
> > Strings cannot *contain* \0., they are still \0 terminated.
> 
> Why not? This is a time where the old C-style "string"-convention has been
> long forgone.
> 
> There are plenty of programming languages that allow strings to contain \0.
> Their implementations do not require to have strings terminated by \0.
> 
> A library/transport should be language-agnostic w.r.t. strings. An
> implementation that forces the old C-style convention for "strings" to be
> terminated with a nul byte \0 does not appear to be very "up-to-date".
> Also, not defining an explicit string encoding in a world that uses all
> kinds of different string encodings appears to be quite error-prone.

Hold on. Let's remember two things:

1) D-Bus strings are already mandated to be UTF-8. You can't transfer 
arbitrary binary data in it. For that, you need to use array of byte (ay) and 
that has no limitation on which bytes are contained, including NULs.

2) The current libdbus-1 API already has limitations when it comes to 
obtaining strings. The "s" type is considered basic and you can get it via 
either dbus_message_get_args and dbus_message_iter_get_basic, without being 
given a size. Similarly, you append it via dbus_message_append_args and 
dbus_message_iter_append_basic, again without passing a size.

Given those two constraints and especially given the second, it's reasonable 
to assume that no one is passing NULs in D-Bus strings. I'd say it's more than 
acceptable to list the constraint already present.

-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
   Software Architect - Intel Open Source Technology Center
      PGP/GPG: 0x6EF45358; fingerprint:
      E067 918B B660 DBD1 105C  966C 33F5 F005 6EF4 5358
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