add libred_check_timetravel.3

Signed-off-by: Mattias Andrée <maandree@member.fsf.org>

1 files changed, 55 insertions, 0 deletions

diff --git a/doc/man/libred_check_timetravel.3 b/doc/man/libred_check_timetravel.3
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+.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 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>.
+