Create lib/Safeguards.pm to implement new --disk-bytes-free and --disk-pct-free in pt-agent.

t/lib/Safeguards.t

@@ -0,0 +1,69 @@
+#!/usr/bin/perl
+
+BEGIN {
+   die "The PERCONA_TOOLKIT_BRANCH environment variable is not set.\n"
+      unless $ENV{PERCONA_TOOLKIT_BRANCH} && -d $ENV{PERCONA_TOOLKIT_BRANCH};
+   unshift @INC, "$ENV{PERCONA_TOOLKIT_BRANCH}/lib";
+};
+
+use strict;
+use warnings FATAL => 'all';
+use English qw(-no_match_vars);
+use Test::More;
+
+use Safeguards;
+use Percona::Test;
+
+use Data::Dumper;
+$Data::Dumper::Indent    = 1;
+$Data::Dumper::Sortkeys  = 1;
+$Data::Dumper::Quotekeys = 0;
+
+my $sample = "t/lib/samples/bash/";
+
+my $safeguards = Safeguards->new(
+   disk_bytes_free => 104857600,
+   disk_pct_free   => 10,
+);
+
+# Filesystem   1024-blocks     Used Available Capacity  Mounted on
+# /dev/disk0s2   118153176 94409664  23487512    81%    /
+#
+# Those values are in Kb, so:
+#   used     = 94409664 (94.4G) = 96_675_495_936 bytes
+#   free     = 23487512 (23.4G) = 24_051_212_288 bytes
+#   pct free = 100 - 81         = 19 %
+my $df = slurp_file("$trunk/$sample/diskspace001.txt");
+
+ok(
+   $safeguards->check_disk_space(
+      disk_space => $df,
+   ),
+   "diskspace001: Enough bytes and pct free"
+);
+
+$safeguards = Safeguards->new(
+   disk_bytes_free => 104857600,
+   disk_pct_free   => 20,
+);
+
+ok(
+   !$safeguards->check_disk_space(
+      disk_space => $df,
+   ),
+   "diskspace001: Not enough pct free"
+);
+
+$safeguards = Safeguards->new(
+   disk_bytes_free => 24_051_212_289,
+   disk_pct_free   => 5,
+);
+
+ok(
+   !$safeguards->check_disk_space(
+      disk_space => $df,
+   ),
+   "diskspace001: Not enough bytes free"
+);
+
+done_testing;