.TH LIBRED_CHECK_TIMETRAVEL 3 LIBRED
.SH NAME
libred_check_timetravel \- Exit the process if the clock is too far in the past
.SH SYNOPSIS
.nf
#include <libred.h>

int \fBlibred_check_timetravel\fP(void);
.fi
.PP
Link with
.IR -lred .
.SH DESCRIPTION
.B libred_check_timetravel
exits the process if
.B libred
is not compiled to support the current time, which is the case
if it was compiled without
.I \-DTIMETRAVELLER
and the clock is before year 2000.5 in the Julian calendar. Before
exiting, the function will print an informative error message to
standard error.
.SH "RETURN VALUE"
Upon successful completion, without time incompatibility, the function
returns 0. Upon failure, that is, it is unable to read the clock, the
function returns -1.
.SH ERRORS
The function may fail for any reason specified for
.BR clock_gettime (3),
and set the value of
.B errno
to the same values.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.BR libred.h (0),
.BR libred (7),
.BR libred_solar_elevation (3)
.SH LICENSE
Copyright \(co 2016  Mattias Andrée
.br
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
.br
This is free software: you are free to change and redistribute it.
.br
There is NO WARRANTY, to the extent permitted by law.
.PP
Copying and distribution of this manual, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.  This file is offered as-is,
without any warranty.
.SH BUGS
Please report bugs to <https://github.com/maandree/libred/issues>
or to <maandree@member.fsf.org>.