bluez中GATT服务的回调方法如何？

Question

When adding a GATT Service using BlueZ (using 'gatt_service_add()') you can specify various callback methods for ATTRIB_READ, ATTRIB_WRITE, etc. There is an example for 'reading' the characteristics already given:

static uint8_t battery_state_read(struct attribute *a,  struct btd_device *device, gpointer user_data);

How do the methods look like for other features (eg: write)?

Answer 1

I've been working with bluez 4.101 recently bringing up a GATT server, you'll want to take a look at "linkloss.c" located (in bluez 4.101 at least) in the "proximity" directory. Or here I guess: https://github.com/pauloborges/bluez/blob/master/profiles/proximity/linkloss.c

The link loss service is registered with writable callbacks like:

svc_added = gatt_service_add(adapter,
        GATT_PRIM_SVC_UUID, &uuid,
        /* Alert level characteristic */
        GATT_OPT_CHR_UUID16, ALERT_LEVEL_CHR_UUID,
        GATT_OPT_CHR_PROPS,
            ATT_CHAR_PROPER_READ | ATT_CHAR_PROPER_WRITE,
        GATT_OPT_CHR_VALUE_CB, ATTRIB_READ,
            link_loss_alert_lvl_read, lladapter,
        GATT_OPT_CHR_VALUE_CB, ATTRIB_WRITE,
            link_loss_alert_lvl_write, lladapter,
        GATT_OPT_CHR_VALUE_GET_HANDLE,
            &lladapter->alert_lvl_value_handle,
        GATT_OPT_INVALID);

Where the callback structure is like:

static uint8_t link_loss_alert_lvl_write(struct attribute *a, struct btd_device *device, gpointer user_data)
{
 /*stuff*/
}

The "attribute" struct contains the data passed to the writable callback.