.\"
.\" libdivecomputer
.\"
.\" Copyright (C) 2017 Kristaps Dzonsons <kristaps@bsd.lv>
.\"
.\" This library is free software; you can redistribute it and/or
.\" modify it under the terms of the GNU Lesser General Public
.\" License as published by the Free Software Foundation; either
.\" version 2.1 of the License, or (at your option) any later version.
.\"
.\" This library is distributed in the hope that it will be useful,
.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
.\" Lesser General Public License for more details.
.\"
.\" You should have received a copy of the GNU Lesser General Public
.\" License along with this library; if not, write to the Free Software
.\" Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
.\" MA 02110-1301 USA
.\"
.Dd January 5, 2017
.Dt DC_DEVICE_SET_CANCEL 3
.Os
.Sh NAME
.Nm dc_device_set_cancel
.Nd callback to check whether processing should cancel
.Sh LIBRARY
.Lb libdivecomputer
.Sh SYNOPSIS
.In libdivecomputer/device.h
.Ft "typedef int"
.Fo "(*dc_cancel_callback_t)"
.Fa "void *userdata"
.Fc
.Ft dc_status_t
.Fo dc_device_set_cancel
.Fa "dc_device_t *device"
.Fa "dc_cancel_callback_t callback"
.Fa "void *userdata"
.Fc
.Sh DESCRIPTION
Provide a function that the underlying
.Fa device
will periodically call to see if it should cancel its processing.
The
.Fa callback
will return zero if the operation should not be cancelled, one if it
should be cancelled.
.Pp
The callback usually checks a value that is set during a signal handling
callback.
For example, one can invoke
.Xr signal 3
to a function that sets a
.Vt "volatile sig_atomic_t"
value checked by the
.Fa callback
handler.
.Sh RETURN VALUES
Returns
.Dv DC_STATUS_UNSUPPORTED
if the
.Fa device
is
.Dv NULL ,
or
.Dv DC_STATUS_SUCCESS
otherwise.
.Sh SEE ALSO
.Xr dc_device_open 3
.Sh AUTHORS
The
.Lb libdivecomputer
library was written by
.An Jef Driesen ,
.Mt jef@libdivecomputer.org .
These manpages were written by
.An Kristaps Dzonsons ,
.Mt kristaps@bsd.lv .