#!/usr/bin/perl
#
# This program will trim the CVS history file. It must be run by
# somebody who can write to the CVSROOT directory in the actual
# repository directory.
#
# It has two built-in numbers, the number of lines to leave the
# history file at, and the number of lines the history file must
# be to need trimming.  The difference is the number of lines
# created between trimmings.
#
# It will create a file called history.trim.?, where the ? is a
# sequential number, and will write the trimmed-off part to that
# file.  It will create a new file, arbitrarily named, to write
# the rest of the history file to, and then will unlink the previous
# history file and rename the new file to "history".
#

#Copyright 2002, David H. Thornley.
#Permission granted to use under Gnu General Public License, version 2 or later.
#This license is available at http://www.thornleyweb.com/perl/license.html
#No warranty, express or implied, except by separate agreement.

my ($minimum_history_size) = 300;
my ($maximum_history_size) = 600;

my ($history_line_count) = 0;

open HISTORY, "history" or die "No history file found";

while (<HISTORY>) {
   ++$history_line_count;
}

if ($history_line_count <= $maximum_history_size) { 
   exit 0;
}

seek HISTORY, 0, 0 or
   die "Could not rewind history file";

my ($lines_to_trim) = $history_line_count - $minimum_history_size;
my ($history_trim_suffix) = 1;

while (-e "history_trim.$history_trim_suffix") {
   ++$history_trim_suffix;
}

open HISTORY_TRIM, ">history_trim.$history_trim_suffix" or 
   die "Could not open file to write old history to";

open NEW_HISTORY, ">history.new" or
   die "Could not open history.new file";

$history_line_count = 0;

while (<HISTORY>) {
   ++$history_line_count;
   if ($history_line_count <= $lines_to_trim) {
      print HISTORY_TRIM;
   } else {
      print NEW_HISTORY;
   }
}

close HISTORY, HISTORY_TRIM, NEW_HISTORY;

rename("history.new", "history");

exit 0;