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|
#!/usr/bin/perl
use strict;
use warnings;
use Getopt::Long;
my $UNION_GRUB_CFG = '/live/image/boot/grub/grub.cfg';
# this function parses the grub config file and returns a hash reference
# of the parsed data.
sub parseGrubCfg {
my $fd = undef;
return undef if (!open($fd, '<', $UNION_GRUB_CFG));
my %ghash = ();
my @entries = ();
my $in_entry = 0;
my $idx = 0;
while (<$fd>) {
if ($in_entry) {
if (/^}/) {
$in_entry = 0;
++$idx;
} elsif (/^\s+linux /) {
my %ehash = (
'idx' => $idx,
'ver' => undef,
'term' => undef,
'reset' => undef
);
# kernel line
if (/^\s+linux \/boot\/([^\/ ]+)\/.* boot=live /) {
# union install
$ehash{'ver'} = $1;
} else {
# old install
$ehash{'ver'} = 'Old non-image installation';
}
if (/console=tty0.*console=ttyS0/) {
$ehash{'term'} = 'serial';
} else {
$ehash{'term'} = 'kvm';
}
if (/standalone_root_pw_reset/) {
$ehash{'reset'} = 1;
} else {
$ehash{'reset'} = 0;
}
push @entries, \%ehash;
}
} elsif (/^set default=(\d+)$/) {
$ghash{'default'} = $1;
} elsif (/^menuentry /) {
$in_entry = 1;
}
}
close($fd);
$ghash{'entries'} = \@entries;
return \%ghash;
}
# this function takes the default terminal type and a list of all entries
# and returns the "boot list", i.e., the list for user to select which one
# to boot.
sub getBootList {
my ($dterm, $entries) = @_;
my %vhash = ();
my @list = ();
foreach (@{$entries}) {
my ($ver, $term) = ($_->{'ver'}, $_->{'term'});
next if ($_->{'reset'}); # skip password reset entry
next if ($term ne $dterm); # not the default terminal
next if (defined($vhash{$ver})); # version already in list
$vhash{$ver} = 1;
push @list, $_;
}
return \@list;
}
sub displayBootList {
my ($didx, $entries) = @_;
for my $i (0 .. $#{$entries}) {
my $di = $i + 1;
my $ver = ${$entries}[$i]->{'ver'};
my $m = '';
if ($didx == ${$entries}[$i]->{'idx'}) {
$m = ' (default boot)';
}
printf " %2d: %s%s\n", $di, $ver, $m;
}
}
my ($show, $sel) = (undef, undef);
GetOptions(
'show' => \$show,
'select' => \$sel
);
my $gref = parseGrubCfg();
if (!defined($gref)) {
print "Cannot find GRUB configuration file. Exiting...\n";
exit 1;
}
my $def_idx = $gref->{'default'};
my $entries = $gref->{'entries'};
if (!defined($def_idx) || !defined($entries)
|| !defined(${$entries}[$def_idx])) {
print "Error parsing GRUB configuration file. Exiting...\n";
exit 1;
}
my $def_term = ${$entries}[$def_idx]->{'term'};
my $bentries = getBootList($def_term, $entries);
print "The system currently has the following images installed:\n\n";
displayBootList($def_idx, $bentries);
print "\n";
exit 0 if ($show); # show-only. done.
print 'Select the default boot image: ';
my $resp = <STDIN>;
if (!defined($resp) || !($resp =~ /^\d+$/) || ($resp < 1)
|| ($resp > ($#{$bentries} + 1))) {
print "Invalid selection. Default is not changed. Exiting...\n";
exit 1;
}
print "\n";
$resp -= 1;
my $new_idx = ${$bentries}[$resp]->{'idx'};
my $new_ver = ${$bentries}[$resp]->{'ver'};
system("sed -i 's/^set default=.*\$/set default=$new_idx/' $UNION_GRUB_CFG");
if ($? >> 8) {
print "Failed to set the default boot image. Exiting...\n";
exit 1;
}
print <<EOF;
Default boot image has been set to "$new_ver".
You need to reboot the system to start the new default image.
EOF
exit 0;
|
