[systemd-devel] [PATCH] Big endian and the size of the gcc builtin type bool from stdbool.h

[David Herrmann]

Hi

On Thu, Sep 18, 2014 at 12:57 PM, Dr. Werner Fink <werner at suse.de> wrote:
> On Thu, Sep 18, 2014 at 12:43:00PM +0200, David Herrmann wrote:
>> Hi
>>
>> On Thu, Sep 18, 2014 at 11:16 AM, Werner Fink <werner at suse.de> wrote:
>> > On s390 the big endianness and cast from pointers of integers to
>> > the type of bool leads to the funny status messages that e.g.
>> > all targets are set to AllowIsolate=no even for multi-user.target.
>> >
>> > The gcc builtin type bool or _Bool has the size of one byte which
>> > should be taken into account in sd_bus_message_read_basic() as well
>> > as in bus_message_append_ap()
>>
>> We don't support "bool" in public APIs. sd-bus requires you to use
>> "int" for boolean types. If a caller uses "bool", they must be fixed.
>
> Then I'd like to know why the header <stdbool.h> together with the
> therein provided type _Bool aka bool is used overall systemd. Also

We use stdbool internally quite a lot. Especially bit-fields are
really nice if implemented as bool. We just don't use bool in public
APIs. We also avoid it in combination with va_arg() and with pointers,
as in both cases the behavior is non-obvious and often done wrong.

> it is systemctl which does use sd_bus_message_read_basic() to parse
> the answer received over sd_bus of the status question send over
> sd_bus?

All uses of sd-bus with "bool" are bugs and need to be fixed. See the
history of bus-message.c:

commit 9bcbce4201afada1c0ad8ada0cbfbbf58a52a6a7
Author: Kay Sievers <kay at vrfy.org>
Date:   Tue Oct 22 03:27:38 2013 +0200

    bus: avoid 'bool' storage when retrieving 'b' from the message

commit 102d8f8169427cb68cdebf5ee0f0e07788e9c2b2
Author: Kay Sievers <kay at vrfy.org>
Date:   Thu Nov 7 02:03:10 2013 +0100

    consistently use "int" when retrieving "bool" from bus messages


Thanks
David