USB transfer helpers: libfprint Reference Manual

USB transfer helpers

USB transfer helpers — Helpers for libgusb to ease transfer handling

Functions

void	(*FpiUsbTransferCallback) ()
FpiUsbTransfer *	fpi_usb_transfer_new ()
FpiUsbTransfer *	fpi_usb_transfer_ref ()
void	fpi_usb_transfer_unref ()
void	fpi_usb_transfer_set_short_error ()
void	fpi_usb_transfer_fill_bulk ()
void	fpi_usb_transfer_fill_bulk_full ()
void	fpi_usb_transfer_fill_control ()
void	fpi_usb_transfer_fill_interrupt ()
void	fpi_usb_transfer_fill_interrupt_full ()
void	fpi_usb_transfer_submit ()
gboolean	fpi_usb_transfer_submit_sync ()

Types and Values

#define	FPI_USB_ENDPOINT_IN
#define	FPI_USB_ENDPOINT_OUT
enum	FpiTransferType
	FpiUsbTransfer

Description

FpiUsbTransfer is a structure to simplify the USB transfer handling. The main goal is to ease memory management and provide more parameters to callbacks that are useful for libfprint drivers.

Drivers should use this API only rather than accessing the GUsbDevice directly in most cases.

Functions

FpiUsbTransferCallback ()

void
(*FpiUsbTransferCallback) (FpiUsbTransfer *transfer,
                           FpDevice *dev,
                           gpointer user_data,
                           GError *error);

fpi_usb_transfer_new ()

FpiUsbTransfer *
fpi_usb_transfer_new (FpDevice *device);

Creates a new FpiUsbTransfer.

Parameters

device

The FpDevice the transfer is for

Returns

A newly created FpiUsbTransfer.

[transfer full]

fpi_usb_transfer_ref ()

FpiUsbTransfer *
fpi_usb_transfer_ref (FpiUsbTransfer *self);

Increments the reference count of self by one.

Parameters

self

A FpiUsbTransfer

Returns

self .

[transfer full]

fpi_usb_transfer_unref ()

void
fpi_usb_transfer_unref (FpiUsbTransfer *self);

Decrements the reference count of self by one, freeing the structure when the reference count reaches zero.

Parameters

self

A FpiUsbTransfer

fpi_usb_transfer_set_short_error ()

void
fpi_usb_transfer_set_short_error (FpiUsbTransfer *transfer,
                                  gboolean short_is_error);

fpi_usb_transfer_fill_bulk ()

void
fpi_usb_transfer_fill_bulk (FpiUsbTransfer *transfer,
                            guint8 endpoint,
                            gsize length);

Prepare a bulk transfer. A buffer will be created for you, use fpi_usb_transfer_fill_bulk_full() if you want to send a static buffer or receive a pre-defined buffer.

Parameters

transfer	The FpiUsbTransfer
endpoint	The endpoint to send the transfer to
length	The buffer size to allocate

fpi_usb_transfer_fill_bulk_full ()

void
fpi_usb_transfer_fill_bulk_full (FpiUsbTransfer *transfer,
                                 guint8 endpoint,
                                 guint8 *buffer,
                                 gsize length,
                                 GDestroyNotify free_func);

Prepare a bulk transfer.

Parameters

transfer	The FpiUsbTransfer
endpoint	The endpoint to send the transfer to
buffer	The data to send.
length	The size of `buffer`
free_func	Destroy notify for `buffer` .	[destroy buffer]

fpi_usb_transfer_fill_control ()

void
fpi_usb_transfer_fill_control (FpiUsbTransfer *transfer,
                               GUsbDeviceDirection direction,
                               GUsbDeviceRequestType request_type,
                               GUsbDeviceRecipient recipient,
                               guint8 request,
                               guint16 value,
                               guint16 idx,
                               gsize length);

Prepare a control transfer. The function will create a new buffer, you can initialize the buffer after calling this function.

Parameters

transfer	The FpiUsbTransfer
direction	The direction of the control transfer
request_type	The request type
recipient	The recipient
request	The control transfer request
value	The control transfer value
idx	The control transfer index
length	The size of the transfer

fpi_usb_transfer_fill_interrupt ()

void
fpi_usb_transfer_fill_interrupt (FpiUsbTransfer *transfer,
                                 guint8 endpoint,
                                 gsize length);

Prepare an interrupt transfer. The function will create a new buffer, you can initialize the buffer after calling this function.

Parameters

transfer	The FpiUsbTransfer
endpoint	The endpoint to send the transfer to
length	The size of the transfer

fpi_usb_transfer_fill_interrupt_full ()

void
fpi_usb_transfer_fill_interrupt_full (FpiUsbTransfer *transfer,
                                      guint8 endpoint,
                                      guint8 *buffer,
                                      gsize length,
                                      GDestroyNotify free_func);

Prepare an interrupt transfer.

Parameters

transfer	The FpiUsbTransfer
endpoint	The endpoint to send the transfer to
buffer	The data to send.
length	The size of `buffer`
free_func	Destroy notify for `buffer` .	[destroy buffer]

fpi_usb_transfer_submit ()

void
fpi_usb_transfer_submit (FpiUsbTransfer *transfer,
                         guint timeout_ms,
                         GCancellable *cancellable,
                         FpiUsbTransferCallback callback,
                         gpointer user_data);

Submit a USB transfer with a specific timeout and callback functions.

Note that FpiUsbTransfer will be stolen when this function is called. So that all associated data will be free'ed automatically, after the callback ran unless fpi_usb_transfer_ref() is explicitly called.

Parameters

transfer	The transfer to submit, must have been filled.	[transfer full]
timeout_ms	Timeout for the transfer in ms
cancellable	Cancellable to use, e.g. `fpi_device_get_cancellable()`
callback	Callback on completion or error
user_data	Data to pass to callback

fpi_usb_transfer_submit_sync ()

gboolean
fpi_usb_transfer_submit_sync (FpiUsbTransfer *transfer,
                              guint timeout_ms,
                              GError **error);

Synchronously submit a USB transfer with a specific timeout. Only use this function with short timeouts as the application will be blocked otherwise.

Note that you still need to fpi_usb_transfer_unref() the FpiUsbTransfer afterwards.

Parameters

transfer	The transfer to submit, must have been filled.
timeout_ms	Timeout for the transfer in millisecnods
error	Location to store GError to

Returns

TRUE on success, otherwise FALSE and error will be set

Types and Values

FPI_USB_ENDPOINT_IN

#define FPI_USB_ENDPOINT_IN 0x80

FPI_USB_ENDPOINT_OUT

#define FPI_USB_ENDPOINT_OUT 0x00

enum FpiTransferType

Type of the transfer.

Members

FP_TRANSFER_NONE	Type not set
FP_TRANSFER_CONTROL	Control transfer
FP_TRANSFER_BULK	Bulk transfer
FP_TRANSFER_INTERRUPT	Interrupt transfer

FpiUsbTransfer

typedef struct {
  FpDevice *device;

  FpiSsm   *ssm;

  gssize    length;
  gssize    actual_length;

  guchar   *buffer;
} FpiUsbTransfer;

Helper for handling USB transfers.

Members

FpDevice *`device`;	The FpDevice that the transfer belongs to.
FpiSsm *`ssm`;	Storage slot to associate the transfer with a state machine. Used by `fpi_ssm_usb_transfer_cb()` to modify the given state machine.
gssize `length`;	The requested length of the transfer in bytes.
gssize `actual_length`;	The actual length of the transfer (see also `fpi_usb_transfer_set_short_error()`)
guchar *`buffer`;	The transferred data.