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image-device: Prevent deactivation when waiting for finger

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At the end of enroll, the image device would put the driver into the
AWAIT_FINGER_ON state and then deactivate the device afterwards. Doing
this adds additional complexity to drivers which would need to handle
both cancellation and normal deactivation from that state.

Only put the device into the AWAIT_FINGER_ON state when we know that
another enroll stage is needed. This avoids the critical state
transition simplifying the driver state machine.

Fixes: #203
Fixes: 689aff0232
This commit is contained in:
Benjamin Berg 2019-12-04 15:50:06 +01:00 committed by Benjamin Berg
parent dccb5b3ab2
commit 7b68344394
1 changed files with 28 additions and 3 deletions
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31
libfprint/fp-image-device.c
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@ -51,6 +51,7 @@ typedef struct
FpImageDeviceState state;
gboolean active;
gboolean enroll_await_on_pending;
gint enroll_stage;
guint pending_activation_timeout_id;
@ -256,6 +257,7 @@ fp_image_device_start_capture_action (FpDevice *device)
}
priv->enroll_stage = 0;
priv->enroll_await_on_pending = FALSE;
/* The device might still be deactivating from a previous call.
* In that situation, try to wait for a bit before reporting back an
@ -385,6 +387,22 @@ fp_image_device_init (FpImageDevice *self)
}
static void
fp_image_device_enroll_maybe_await_finger_on (FpImageDevice *self)
{
FpImageDevicePrivate *priv = fp_image_device_get_instance_private (self);
if (priv->enroll_await_on_pending)
{
priv->enroll_await_on_pending = FALSE;
fp_image_device_change_state (self, FP_IMAGE_DEVICE_STATE_AWAIT_FINGER_ON);
}
else
{
priv->enroll_await_on_pending = TRUE;
}
}
static void
fpi_image_device_minutiae_detected (GObject *source_object, GAsyncResult *res, gpointer user_data)
{
@ -446,11 +464,16 @@ fpi_image_device_minutiae_detected (GObject *source_object, GAsyncResult *res, g
fpi_device_enroll_progress (device, priv->enroll_stage,
g_steal_pointer (&print), error);
/* Start another scan or deactivate. */
if (priv->enroll_stage == IMG_ENROLL_STAGES)
{
fpi_device_enroll_complete (device, g_object_ref (enroll_print), NULL);
fp_image_device_deactivate (device);
}
else
{
fp_image_device_enroll_maybe_await_finger_on (FP_IMAGE_DEVICE (device));
}
}
else if (action == FP_DEVICE_ACTION_VERIFY)
{
@ -572,13 +595,15 @@ fpi_image_device_report_finger_status (FpImageDevice *self,
* 2. We are still deactivating the device after an action completed
* 3. We were waiting for finger removal to start the new action
* Either way, we always end up deactivating except for the enroll case.
* XXX: This is not quite correct though, as we assume we need another finger
* scan even though we might be processing the last one (successfully).
*
* The enroll case is special as AWAIT_FINGER_ON should only happen after
* minutiae detection to prevent deactivation (without cancellation)
* from the AWAIT_FINGER_ON state.
*/
if (action != FP_DEVICE_ACTION_ENROLL)
fp_image_device_deactivate (device);
else
fp_image_device_change_state (self, FP_IMAGE_DEVICE_STATE_AWAIT_FINGER_ON);
fp_image_device_enroll_maybe_await_finger_on (self);
}
}