NAME

     fido_dev_get_touch_begin, fido_dev_get_touch_status — asynchronously wait for touch on a
     FIDO2 authenticator

SYNOPSIS

     #include <fido.h>

     int
     fido_dev_get_touch_begin(fido_dev_t *dev);

     int
     fido_dev_get_touch_status(fido_dev_t *dev, int *touched, int ms);

DESCRIPTION

     The functions described in this page allow an application to asynchronously wait for touch
     on a FIDO2 authenticator.  This is useful when multiple authenticators are present and the
     application needs to know which one to use.

     The fido_dev_get_touch_begin() function initiates a touch request on dev.

     The fido_dev_get_touch_status() function continues an ongoing touch request on dev, blocking
     up to ms milliseconds.  On success, touched will be updated to reflect the touch request
     status.  If touched is 1, the device was touched, and the touch request is terminated.  If
     touched is 0, the application may call fido_dev_get_touch_status() to continue the touch
     request, or fido_dev_cancel() to terminate it.

RETURN VALUES

     The error codes returned by fido_dev_get_touch_begin() and fido_dev_get_touch_status() are
     defined in <fido/err.h>.  On success, FIDO_OK is returned.

EXAMPLES

     Please refer to examples/select.c in libfido2's source tree.

SEE ALSO

     fido_dev_cancel(3)

CAVEATS

     The fido_dev_get_touch_status() function will cause a command to be transmitted to U2F
     authenticators.  These transmissions should not exceed a frequency of 5Hz.