/usr/bin/linux-check-removal is in linux-base 4.5ubuntu1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 | #!/usr/bin/perl
# Copyright 1996-2006 Manoj Srivastava
# Copyright 2016 Ben Hutchings
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
use strict;
use warnings;
use FileHandle;
use POSIX ();
sub usage {
my $fh = shift;
print $fh (<< "EOT");
Usage: $0 VERSION
This command is intended to be called from the prerm maintainer scripts
of Linux kernel packages.
The VERSION argument must be the kernel version string as shown by
'uname -r' and used in filenames.
If the currently running kernel matches VERSION, linux-check-removal
will normally prompt the user to confirm this potentially dangerous
action and will fail if the user chooses to abort. However, if the
current environment is in a chroot or container, or if debconf
prompts are disabled, it will always succeed without prompting.
EOT
}
sub usage_error {
usage(*STDERR{IO});
exit 2;
}
# Check usage early, before Debconf::Client::ConfModule initialises and
# adds its complaints about permissions
BEGIN {
if (@ARGV != 1) {
usage_error();
}
if ($ARGV[0] eq 'help' or grep({$_ eq '--help'} @ARGV)) {
usage(*STDOUT{IO});
exit 0;
}
}
# Are we in a container? Check for $container in pid 1's environment.
sub in_container {
my $res = 0;
if (my $fh = new FileHandle('/proc/1/environ', 'r')) {
local $/ = "\0";
$res = grep(/^container=/, <$fh>);
close($fh);
}
return $res;
}
# Are we in in a chroot? Compare root device and inode numbers with pid 1.
sub in_chroot {
my @my_root_st = stat('/');
my @pid1_root_st = stat('/proc/1/root');
return @my_root_st && @pid1_root_st &&
($my_root_st[0] != $pid1_root_st[0] || $my_root_st[1] != $pid1_root_st[1]);
}
sub check {
my ($version) = @_;
my (undef, undef, $running, undef, undef) = POSIX::uname();
if ($running ne $version || in_chroot() || in_container()) {
exit 0;
}
if (!exists($ENV{'DEBIAN_FRONTEND'}) ||
$ENV{'DEBIAN_FRONTEND'} ne 'noninteractive') {
use Debconf::Client::ConfModule qw(:all);
my $title = 'linux-base/removing-title';
my $question = "linux-base/removing-running-kernel";
my ($ret, $seen, $answer);
# debconf only generates a title automatically when used directly
# from a maintainer script. Also, the automatic title says we are
# 'configuring' a package but we're not.
($ret) = subst($title, 'package', $ENV{DPKG_MAINTSCRIPT_PACKAGE});
if ($ret) {
die "Failed to substitute package name in title: $ret";
}
($ret) = settitle($title);
if ($ret) {
die "Failed to set title: $ret";
}
($ret) = fset($question, 'seen', 'false');
if ($ret) {
die "Failed to reset seen flag for $question: $ret";
}
($ret) = reset($question);
if ($ret) {
die "Failed to reset answer for $question: $ret";
}
($ret) = subst($question, 'running', $running);
if ($ret) {
die "Failed to substitute version in $question: $ret";
}
($ret, $seen) = input('critical', $question);
if ($ret && $ret != 30) {
die "Failed to prepare question $question: $ret $seen";
}
($ret, $seen) = go();
if ($ret && $ret != 30) {
die "Failed to ask question $question: $ret $seen";
}
($ret, $answer) = get($question);
if ($ret) {
die "Failed to retrieve answer for $question: $ret $answer";
}
if ($answer eq 'true') {
print STDERR "E: Aborting removal of the running kernel\n";
exit 1;
}
}
print STDERR "W: Removing the running kernel\n";
exit 0;
}
check(@ARGV);
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