[systemd-devel] [PATCH 3/7] libsystemd-bus: add kdbus support for sd_bus_list_names()

[Lukasz Skalski]

My 2 cents inline.

On 11/15/2013 07:32 PM, Daniel Mack wrote:
> kdbus will tell us the minimum buffer size it needs in case the default
> 8kb buffer doesn't suffice.
> ---
>   src/libsystemd-bus/bus-control.c | 100 ++++++++++++++++++++++++++-------------
>   1 file changed, 68 insertions(+), 32 deletions(-)
>
> diff --git a/src/libsystemd-bus/bus-control.c b/src/libsystemd-bus/bus-control.c
> index 5c9e746..562513b 100644
> --- a/src/libsystemd-bus/bus-control.c
> +++ b/src/libsystemd-bus/bus-control.c
> @@ -180,43 +180,79 @@ _public_ int sd_bus_list_names(sd_bus *bus, char ***l) {
>           if (bus_pid_changed(bus))
>                   return -ECHILD;
>
> -        r = sd_bus_call_method(
> -                        bus,
> -                        "org.freedesktop.DBus",
> -                        "/",
> -                        "org.freedesktop.DBus",
> -                        "ListNames",
> -                        NULL,
> -                        &reply1,
> -                        NULL);
> -        if (r < 0)
> -                return r;
> +        if (bus->is_kernel) {
> +                _cleanup_free_ struct kdbus_cmd_names *names = NULL;
> +                struct kdbus_cmd_name *name;
> +                size_t size;
> +
> +                /* assume 8k size first. If that doesn't suffice, kdbus will tell us
> +                 * how big the buffer needs to be.  */
> +                size = 8192;
> +
> +retry:
> +                names = realloc(names, size);
> +                if (!names)
> +                        return log_oom();
> +
> +                names->size = size;

+ names->flags=KDBUS_NAME_LIST_UNIQUE_NAMES;

"ListNames" should returns a list of all (both well-known and unique 
names) currently-owned names on the bus.

> +
> +                r = ioctl(sd_bus_get_fd(bus), KDBUS_CMD_NAME_LIST, names);
> +                if (r < 0) {
> +                        if (errno == ENOBUFS && size != names->size) {
> +                                size = names->size;
> +                                goto retry;
> +                        }
>
> -        r = sd_bus_call_method(
> -                        bus,
> -                        "org.freedesktop.DBus",
> -                        "/",
> -                        "org.freedesktop.DBus",
> -                        "ListActivatableNames",
> -                        NULL,
> -                        &reply2,
> -                        NULL);
> -        if (r < 0)
> -                return r;
> +                        return -errno;
> +                }
>
> -        r = bus_message_read_strv_extend(reply1, &x);
> -        if (r < 0) {
> -                strv_free(x);
> -                return r;
> -        }
> +                KDBUS_PART_FOREACH(name, names, names) {
> +                        r = strv_extend(&x, name->name);
> +                        if (r < 0)
> +                                return log_oom();
> +                }
>
> -        r = bus_message_read_strv_extend(reply2, &x);
> -        if (r < 0) {
> -                strv_free(x);
> -                return r;
> +                *l = x;
> +        } else {
> +                r = sd_bus_call_method(
> +                                bus,
> +                                "org.freedesktop.DBus",
> +                                "/",
> +                                "org.freedesktop.DBus",
> +                                "ListNames",
> +                                NULL,
> +                                &reply1,
> +                                NULL);
> +                if (r < 0)
> +                        return r;
> +
> +                r = sd_bus_call_method(
> +                                bus,
> +                                "org.freedesktop.DBus",
> +                                "/",
> +                                "org.freedesktop.DBus",
> +                                "ListActivatableNames",
> +                                NULL,
> +                                &reply2,
> +                                NULL);
> +                if (r < 0)
> +                        return r;
> +
> +                r = bus_message_read_strv_extend(reply1, &x);
> +                if (r < 0) {
> +                        strv_free(x);
> +                        return r;
> +                }
> +
> +                r = bus_message_read_strv_extend(reply2, &x);
> +                if (r < 0) {
> +                        strv_free(x);
> +                        return r;
> +                }
> +
> +                *l = strv_uniq(x);
>           }
>
> -        *l = strv_uniq(x);
>           return 0;
>   }
>
>

-- 
Lukasz Skalski
Samsung R&D Institute Poland
Samsung Electronics
l.skalski at partner.samsung.com