[pulseaudio-discuss] [PATCH 37/56] bluetooth: Parse BlueZ 5 device properties
João Paulo Rechi Vita
jprvita at gmail.com
Tue Aug 6 08:05:13 PDT 2013
On Mon, Jul 29, 2013 at 8:40 AM, Tanu Kaskinen
<tanu.kaskinen at linux.intel.com> wrote:
> On Thu, 2013-07-25 at 01:44 -0300, João Paulo Rechi Vita wrote:
>> On Mon, Jul 22, 2013 at 7:33 AM, Tanu Kaskinen
>> <tanu.kaskinen at linux.intel.com> wrote:
>> > On Fri, 2013-07-12 at 15:06 -0300, jprvita at gmail.com wrote:
>> >> +static int parse_device_property(pa_bluetooth_device *d, DBusMessageIter *i, bool is_property_change) {
>> >> + const char *key;
>> >> + DBusMessageIter variant_i;
>> >> +
>> >> + pa_assert(d);
>> >> +
>> >> + key = pa_bluetooth_dbus_check_variant_property(i);
>> >> + if (key == NULL) {
>> >> + pa_log_error("Received invalid property for device %s", d->path);
>> >> + return -1;
>> >> + }
>> >> +
>> >> + dbus_message_iter_recurse(i, &variant_i);
>> >> +
>> >> + switch (dbus_message_iter_get_arg_type(&variant_i)) {
>> >> +
>> >> + case DBUS_TYPE_STRING: {
>> >> + const char *value;
>> >> + dbus_message_iter_get_basic(&variant_i, &value);
>> >> +
>> >> + if (pa_streq(key, "Alias")) {
>> >> + pa_xfree(d->alias);
>> >> + d->alias = pa_xstrdup(value);
>> >> + } else if (pa_streq(key, "Address")) {
>> >> + if (is_property_change) {
>> >> + pa_log_error("Device property 'Address' expected to be constant but changed for %s", d->path);
>> >> + return -1;
>> >> + }
>> >> +
>> >> + if (d->address) {
>> >> + pa_log_error("Device %s: Received a duplicate Address property.", d->path);
>> >> + return -1;
>> >> + }
>> >> +
>> >> + d->address = pa_xstrdup(value);
>> >> + }
>> >> +
>> >> + pa_log_debug("%s: %s", key, value);
>> >
>> > Please use proper sentences in the log. Or is this a temporary log
>> > message that you just forgot to remove from the final patch?
>> >
>>
>> This is usually received when the device is created, together with a
>> lot of other properties, so I think is better to minimize verbosity
>> here. What I'll change to improve this scenario is add a log in the
>> beginning of the function with the device path.
>
> I would actually prefer to drop the message altogether. If the property
> is interesting to us, its value will probably appear elsewhere anyway
> (when the property changes, a change message should be printed, and when
> receiving the initial properties, the properties should be printed once
> the parsing is complete). This will also print properties that aren't
> interesting to us, which just adds noise, and it's not even consistent,
> because only string and uint32 properties will be printed.
>
This piece of code will actually do exactly as you described as
desired, it will print only the properties that are interesting to us,
when the property changes, or when receiving the initial properties.
This function, parse_device_property(), is only called from
parse_device_properties(), which in turn is only called on the
following situations: 1) when parsing all the interfaces and
properties in the reply of a GetManagedObjects() call; 2) when parsing
all the interfaces and properties that came with an InterfacesAdded
signal; and 3) when a
org.freedesktop.DBus.Properties.PropertiesChanged signal is received,
with a dictionary containing the changed properties with the new
values. Note that in 3 we'll only print a debug message with the
property and value for the properties which the change have been
notified in that message.
A debug log of these situations will look like this (I've now added
the message that says "Properties changed in device %s"):
- with the device already created prior to PulseAudio's start
(1)
D: [memcheck-amd64-] bluez5-util.c: Device
/org/bluez/hci0/dev_00_0D_3C_B1_B5_5C found
D: [memcheck-amd64-] bluez5-util.c: Address: 00:0D:3C:B1:B5:5C
D: [memcheck-amd64-] bluez5-util.c: Name: Nokia BH-503
D: [memcheck-amd64-] bluez5-util.c: Alias: Nokia BH-503
D: [memcheck-amd64-] bluez5-util.c: Class: 2360324
D: [memcheck-amd64-] bluez5-util.c: Icon: audio-card
D: [memcheck-amd64-] bluez5-util.c: UUIDs: 00001108-0000-1000-8000-00805f9b34fb
D: [memcheck-amd64-] bluez5-util.c: UUIDs: 0000110b-0000-1000-8000-00805f9b34fb
D: [memcheck-amd64-] bluez5-util.c: UUIDs: 0000110c-0000-1000-8000-00805f9b34fb
D: [memcheck-amd64-] bluez5-util.c: UUIDs: 0000110d-0000-1000-8000-00805f9b34fb
D: [memcheck-amd64-] bluez5-util.c: UUIDs: 0000110e-0000-1000-8000-00805f9b34fb
D: [memcheck-amd64-] bluez5-util.c: UUIDs: 0000111e-0000-1000-8000-00805f9b34fb
- during device creation
(First the user put the adapter in inquiry mode, to find visible
devices nearby. When the device is found the device object is created
BlueZ and the following messages are printed.)
(2)
D: [memcheck-amd64-] bluez5-util.c: Device
/org/bluez/hci0/dev_00_23_7F_20_43_F5 found
D: [memcheck-amd64-] bluez5-util.c: Address: 00:23:7F:20:43:F5
D: [memcheck-amd64-] bluez5-util.c: Name: 8XXPlantronics
D: [memcheck-amd64-] bluez5-util.c: Alias: 8XXPlantronics
D: [memcheck-amd64-] bluez5-util.c: Class: 2360324
D: [memcheck-amd64-] bluez5-util.c: Icon: audio-card
(And only after the device is paired the services are resolved and the
UUIDs are emitted.)
(3)
D: [memcheck-amd64-] bluez5-util.c: Properties changed in device
/org/bluez/hci0/dev_00_23_7F_20_43_F5
D: [memcheck-amd64-] bluez5-util.c: UUIDs: 00001108-0000-1000-8000-00805f9b34fb
D: [memcheck-amd64-] bluez5-util.c: UUIDs: 0000110b-0000-1000-8000-00805f9b34fb
D: [memcheck-amd64-] bluez5-util.c: UUIDs: 0000110e-0000-1000-8000-00805f9b34fb
D: [memcheck-amd64-] bluez5-util.c: UUIDs: 0000111e-0000-1000-8000-00805f9b34fb
>> >> +
>> >> + pa_log_debug("%s: %d", key, value);
>> >> + break;
>> >> + }
>> >> +
>> >> + case DBUS_TYPE_ARRAY: {
>> >> + DBusMessageIter ai;
>> >> + dbus_message_iter_recurse(&variant_i, &ai);
>> >> +
>> >> + if (dbus_message_iter_get_arg_type(&ai) == DBUS_TYPE_STRING && pa_streq(key, "UUIDs")) {
>> >> + while (dbus_message_iter_get_arg_type(&ai) != DBUS_TYPE_INVALID) {
>> >> + pa_bluetooth_uuid *node;
>> >> + const char *value;
>> >> +
>> >> + dbus_message_iter_get_basic(&ai, &value);
>> >> +
>> >> + if (pa_bluetooth_uuid_has(d->uuids, value)) {
>> >> + dbus_message_iter_next(&ai);
>> >> + continue;
>> >> + }
>> >> +
>> >> + node = pa_bluetooth_uuid_new(value);
>> >> + PA_LLIST_PREPEND(pa_bluetooth_uuid, d->uuids, node);
>> >> +
>> >> + pa_log_debug("%s: %s", key, value);
>> >> + dbus_message_iter_next(&ai);
>> >
>> > This code only adds UUIDs to pa_bluetooth_device, never removes them. Is
>> > this intentional? If so, I think a comment explaining the rationale
>> > would be good.
>> >
>> > There aren't any hooks that would be fired when the properties (Alias,
>> > Class, UUIDs) change. Perhaps you implement them in some later patches?
>> >
>>
>> This is used to create card profiles on load of module-bluez5-device.
>> It is possible (although not likely) that a device change the
>> implemented UUIDs during the connection lifetime. Alias can change,
>> but I think this should be handled in a separate patch (I've not
>> written that yet).
>
> It's not clear what changes you plan to do (as separate patches or
> otherwise). If it's possible that UUIDs get removed, we should handle
> that.
>
Sorry, I wasn't clear enough. It's possible that a remote device
removes a UUID from its list of supported services. But in BlueZ we'll
never detect this situation, so the UUIDs property will not change in
the device object. What will happen is that if BlueZ tries to connect
to that service the connection will fail. I agree it's an
implementation detail, but if we write code to handle UUIDs removal it
will never be exercised with the current BlueZ implementation.
>> >> @@ -430,8 +604,8 @@ static void parse_interfaces_and_properties(pa_bluetooth_discovery *y, DBusMessa
>> >>
>> >> pa_log_debug("Device %s found", path);
>> >>
>> >> - pa_bluetooth_discovery_create_device(y, path);
>> >> - /* TODO: parse device properties */
>> >> + d = pa_bluetooth_discovery_create_device(y, path);
>> >> + parse_device_properties(d, &iface_i, false);
>> >
>> > If parsing the device properties fails, we shouldn't create the device.
>> >
>>
>> parse_device_properties() will fail even if the parsing of an optional
>> property fails, but the device is still fully usable, so we should
>> still create the device in this case.
>
> That's a matter of taste, and my taste is to fail if bluetoothd
> misbehaves in order to catch bugs earlier.
>
>> To differentiate between these
>> two situations there is the device_info_valid field. Maybe we can
>> review the necessity of the device_info_valid field, but since this
>> affects the modules working logic and may introduce bugs I would
>> prefer to change that in a latter moment to minimize the impact.
>
> Good point, so the correct way to fail would be to set device_info_valid
> to -1.
>
Ok.
--
João Paulo Rechi Vita
http://about.me/jprvita
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