postinst

#! /usr/bin/perl
# OriginalAuthor : Manoj Srivastava ( srivasta@pilgrim.umass.edu )
#
# Customized for Ubuntu by: Ben Collins <bcollins@ubuntu.com>

#use strict; #for debugging
use Cwd 'abs_path';

$|=1;

# Predefined values:
my $version           = "4.15.0-13-lowlatency";
my $link_in_boot      = "";  # Should be empty, mostly
my $no_symlink        = "";   # Should be empty, mostly
my $reverse_symlink   = "";   # Should be empty, mostly
my $do_symlink        = "Yes";  # target machine defined
my $do_boot_enable    = "Yes";  # target machine defined
my $do_bootfloppy     = "Yes";  # target machine defined
my $do_bootloader     = "Yes";  # target machine defined
my $move_image        = '';     # target machine defined
my $kimage            = "vmlinuz";   # Should be empty, mostly
my $loader            = "grub"; # lilo, silo, quik, palo, vmelilo, nettrom, arcboot or delo
my $image_dir         = "/boot";        # where the image is located
my $clobber_modules   = '';          # target machine defined
my $relative_links    = "";          # target machine defined
my $initrd            = "YES";        # initrd kernel
my $do_initrd         = '';     # Normally we do not
my $use_hard_links    = ''; # hardlinks do not work across fs boundaries
my $postinst_hook     = '';          #Normally we do not
my $postrm_hook       = '';          #Normally we do not
my $preinst_hook      = '';          #Normally we do not
my $prerm_hook        = '';          #Normally we do not
my $minimal_swap      = '';          # Do not swap symlinks
my $ignore_depmod_err = '';          # normally we do not
my $kernel_arch       = "x86";
my $ramdisk           = "/usr/sbin/update-initramfs";  # List of tools to create initial ram fs.
my $notifier          = "/usr/share/update-notifier/notify-reboot-required";
my $package_name      = "linux-image-$version";
my $explicit_do_loader = 'Yes';

my $Loader          = "NoLOADER"; #
$Loader             = "LILO"     if $loader =~ /^lilo/io;
$Loader             = "SILO"     if $loader =~ /^silo/io;
$Loader             = "QUIK"     if $loader =~ /^quik/io;
$Loader             = "yaboot"   if $loader =~ /^yaboot/io;
$Loader             = "PALO"     if $loader =~ /^palo/io;
$Loader             = "NETTROM"  if $loader =~ /^nettrom/io;
$Loader             = "VMELILO"  if $loader =~ /^vmelilo/io;
$Loader             = "ZIPL"     if $loader =~ /^zipl/io;
$Loader             = "ELILO"    if $loader =~ /^elilo/io;
$Loader             = "ARCBOOT"  if $loader =~ /^arcboot/io;
$Loader             = "DELO"     if $loader =~ /^delo/io;

# This should not point to /tmp, because of security risks.
my $temp_file_name = "/var/log/$loader" . "_log.$$";

#known variables
my $image_dest      = "/";
my $realimageloc    = "/$image_dir/";
my $have_conffile   = "";
my $silent_modules  = '';
my $silent_loader   = '';
my $warn_reboot     = 'Yes';     # Warn that we are installing a version of
                                 # the kernel we are running

my $modules_base    = '/lib/modules';
my $CONF_LOC        = '/etc/kernel-img.conf';

# Ignore all invocations except when called on to configure.
exit 0 unless $ARGV[0] =~ /configure/;

my $DEBUG = 0;

# Do some preliminary sanity checks here to ensure we actually have an
# valid image dir
chdir('/')           or die "could not chdir to /:$!\n";
die "Internal Error: ($image_dir) is not a directory!\n"
  unless -d $image_dir;

# remove multiple leading slashes; make sure there is at least one.
$realimageloc  =~ s|^/*|/|o;
$realimageloc  =~ s|/+|/|o;
die "Internal Error: ($realimageloc) is not a directory!\n"
  unless -d $realimageloc;

if (-r "$CONF_LOC" && -f "$CONF_LOC"  ) {
  if (open(CONF, "$CONF_LOC")) {
    while (<CONF>) {
      chomp;
      s/\#.*$//g;
      next if /^\s*$/;

      $do_symlink      = "" if /^\s*do_symlinks\s*=\s*(no|false|0)\s*$/ig;
      $no_symlink      = "" if /^\s*no_symlinks\s*=\s*(no|false|0)\s*$/ig;
      $reverse_symlink = "" if /^\s*reverse_symlink\s*=\s*(no|false|0)\s*$/ig;
      $link_in_boot    = "" if /^\s*image_in_boot\s*=\s*(no|false|0)\s*$/ig;
      $link_in_boot    = "" if /^\s*link_in_boot\s*=\s*(no|false|0)\s*$/ig;
      $move_image      = "" if /^\s*move_image\s*=\s*(no|false|0)\s*$/ig;
      $clobber_modules = '' if /^\s*clobber_modules\s*=\s*(no|false|0)\s*$/ig;
      $do_boot_enable  = '' if /^\s*do_boot_enable\s*=\s*(no|false|0)\s*$/ig;
      $do_bootfloppy   = '' if /^\s*do_bootfloppy\s*=\s*(no|false|0)\s*$/ig;
      $relative_links  = '' if /^\s*relative_links \s*=\s*(no|false|0)\s*$/ig;
      $do_bootloader   = '' if /^\s*do_bootloader\s*=\s*(no|false|0)\s*$/ig;
      $explicit_do_loader = '' if /^\s*do_bootloader\s*=\s*(no|false|0)\s*$/ig;
      $do_initrd       = '' if /^\s*do_initrd\s*=\s*(no|false|0)\s*$/ig;
      $use_hard_links  = '' if /^\s*use_hard_links\s*=\s*(no|false|0)\s*$/ig;
      $silent_modules  = '' if /^\s*silent_modules\s*=\s*(no|false|0)\s*$/ig;
      $silent_loader   = '' if /^\s*silent_loader\s*=\s*(no|false|0)\s*$/ig;
      $warn_reboot     = '' if /^\s*warn_reboot\s*=\s*(no|false|0)\s*$/ig;
      $minimal_swap    = '' if /^\s*minimal_swap\s*=\s*(no|false|0)\s*$/ig;
      $ignore_depmod_err = '' if /^\s*ignore_depmod_err\s*=\s*(no|false|0)\s*$/ig;

      $do_symlink      = "Yes" if /^\s*do_symlinks\s*=\s*(yes|true|1)\s*$/ig;
      $no_symlink      = "Yes" if /^\s*no_symlinks\s*=\s*(yes|true|1)\s*$/ig;
      $reverse_symlink = "Yes" if /^\s*reverse_symlinks\s*=\s*(yes|true|1)\s*$/ig;
      $link_in_boot    = "Yes" if /^\s*image_in_boot\s*=\s*(yes|true|1)\s*$/ig;
      $link_in_boot    = "Yes" if /^\s*link_in_boot\s*=\s*(yes|true|1)\s*$/ig;
      $move_image      = "Yes" if /^\s*move_image\s*=\s*(yes|true|1)\s*$/ig;
      $clobber_modules = "Yes" if /^\s*clobber_modules\s*=\s*(yes|true|1)\s*$/ig;
      $do_boot_enable  = "Yes" if /^\s*do_boot_enable\s*=\s*(yes|true|1)\s*$/ig;
      $do_bootfloppy   = "Yes" if /^\s*do_bootfloppy\s*=\s*(yes|true|1)\s*$/ig;
      $do_bootloader   = "Yes" if /^\s*do_bootloader\s*=\s*(yes|true|1)\s*$/ig;
      $explicit_do_loader = "YES" if /^\s*do_bootloader\s*=\s*(yes|true|1)\s*$/ig;
      $relative_links  = "Yes" if /^\s*relative_links\s*=\s*(yes|true|1)\s*$/ig;
      $do_initrd       = "Yes" if /^\s*do_initrd\s*=\s*(yes|true|1)\s*$/ig;
      $use_hard_links  = "Yes" if /^\s*use_hard_links\s*=\s*(yes|true|1)\s*$/ig;
      $silent_modules  = 'Yes' if /^\s*silent_modules\s*=\s*(yes|true|1)\s*$/ig;
      $silent_loader   = 'Yes' if /^\s*silent_loader\s*=\s*(yes|true|1)\s*$/ig;
      $warn_reboot     = 'Yes' if /^\s*warn_reboot\s*=\s*(yes|true|1)\s*$/ig;
      $minimal_swap    = 'Yes' if /^\s*minimal_swap\s*=\s*(yes|true|1)\s*$/ig;
      $ignore_depmod_err = 'Yes' if /^\s*ignore_depmod_err\s*=\s*(yes|true|1)\s*$/ig;

      $image_dest      = "$1"  if /^\s*image_dest\s*=\s*(\S+)/ig;
      $postinst_hook   = "$1"  if /^\s*postinst_hook\s*=\s*(\S+)/ig;
      $postrm_hook     = "$1"  if /^\s*postrm_hook\s*=\s*(\S+)/ig;
      $preinst_hook    = "$1"  if /^\s*preinst_hook\s*=\s*(\S+)/ig;
      $prerm_hook      = "$1"  if /^\s*prerm_hook\s*=\s*(\S+)/ig;
      $ramdisk         = "$1"  if /^\s*ramdisk\s*=\s*(.+)$/ig;
    }
    close CONF;
    $have_conffile = "Yes";
  }
}

$initrd = '' if (! -x "$ramdisk");

# For some versions of kernel-package, we had this warning in the
# postinst, but the rules did not really interpolate the value in.
# Here is a sanity check.
my $pattern = "=" . "I";
$initrd=~ s/^$pattern$//;

if ($link_in_boot) {
  $image_dest = "/$image_dir/"; # same as realimageloc
}

# Tack on at least one trainling /
$image_dest = "$image_dest/";
$image_dest =~ s|^/*|/|o;
$image_dest =~ s|/+$|/|o;

if (! -d "$image_dest") {
  die "Expected Image Destination dir ($image_dest) to be a valid directory!\n";
}

# sanity
if (!($do_bootfloppy || $do_bootloader)) {
  $do_boot_enable = '';
}
if ($do_symlink && $no_symlink) {
  warn "Both do_symlinks and no_symlinks options enabled; disabling no_symlinks\n";
  $no_symlink = 0;
}

# most of our work is done in $image_dest (nominally /)
chdir("$image_dest") or die "could not chdir to $image_dest:$!\n";

# Paranoid check to make sure that the correct value is put in there
if    (! $kimage)                 { $kimage = "vmlinuz"; } # Hmm. empty
elsif ($kimage =~ m/^b?uImage$/o) { $kimage = "vmlinuz"; } # these produce vmlinuz
elsif ($kimage =~ m/^b?zImage$/o) { $kimage = "vmlinuz"; } # these produce vmlinuz
elsif ($kimage =~ m/^[iI]mage$/o) { my $nop = $kimage;   }
elsif ($kimage =~ m/^vmlinux$/o)  { my $nop = $kimage;   }
else                              { $kimage = "vmlinuz"; } # Default

$ENV{KERNEL_ARCH}=$kernel_arch if $kernel_arch;


die "Internal Error: Could not find image (" . $realimageloc
  . "$kimage-$version)\n" unless -e $realimageloc
  . "$kimage-$version";

# search for the boot loader in the path
my $loader_exec;
($loader_exec = $loader)  =~ s|.*/||;
my ($loaderloc) = grep -x, map "$_/$loader_exec",
  map { length($_) ? $_ : "." }  split /:/, $ENV{PATH};


######################################################################
######################################################################
###########        Test whether a relative symlinkwould be OK #######
######################################################################
######################################################################
sub test_relative {
  my %params = @_;
  my $cwd;

  die "Internal Error: Missing Required paramater 'Old Dir' "
    unless $params{'Old Dir'};
  die "Internal Error: Missing Required paramater New Dir' "
    unless $params{'New Dir'};


  die "Internal Error: No such dir $params{'Old Dir'} "
    unless -d $params{'Old Dir'};
  die "Internal Error: No such dir $params{'New Dir'} "
    unless -d $params{'New Dir'};

  # If the caller specified a test file, and it does not exist try and find
  # another file to use in its stead.  As we are installing kernels we can
  # use any versioned file from this kernel which should be in the same place.
  if (defined $params{'Test File'} and
      ! -f $params{'Old Dir'} . '/' . $params{'Test File'}) {

      my @possible = glob($params{'Old Dir'} . "/*$version*");
      if ($#possible >= 0) {
        $params{'Test File'} = `basename "$possible[0]"`;
        chomp($params{'Test File'});
        warn "Test relative: selected $params{'Test File'}"
          if $DEBUG;
      }
  }

  warn "Test relative: testing $params{'Old Dir'} -> $params{'New Dir'}"
    if $DEBUG;
  chomp($cwd = `pwd`);
  chdir ($params{'New Dir'}) or die "Could not chdir to $params{'New Dir'}:$!";
  my $ok = 0;
  $params{'Old Dir'}  =~ s|^/*||o;
  if (-d $params{'Old Dir'} ) {
    if (defined $params{'Test File'}) {
      if (-e $params{'Old Dir'} . $params{'Test File'}) {
        $ok  = 1;
      }
    } else {
      $ok = 1;                  # well, backward compatibility
    }
  }
  chdir ($cwd) or die "Could not chdir to $params{'New Dir'}:$!";
  return $ok;
}

######################################################################
######################################################################
############
######################################################################
######################################################################
# sub CanonicalizePath {
#   my $path = join '/', @_;
#   my @work = split '/', $path;
#   my @out;
#   my $is_absolute;

#   if (@work && $work[0] eq "") {
#     $is_absolute = 1; shift @work;
#   }

#   while (@work) {
#     my $seg = shift @work;
#     if ($seg eq "." || $seg eq "") {
#     } 
#     elsif ($seg eq "..") {
#       if (@out && $out[-1] ne "..") {
#         pop @out;
#       } 
#       else {
#         # Leading "..", or "../..", etc.
#         push @out, $seg;
#       }
#     } 
#     else {
#       push @out, $seg;
#     }
#   }

#   unshift @out, "" if $is_absolute;
#   return join('/', @out);
# }
######################################################################
######################################################################
############
######################################################################
######################################################################

sub spath {
  my %params = @_;

  die "Missing Required paramater 'Old'" unless $params{'Old'};
  die "Missing Required paramater 'New'" unless  $params{'New'};

  my @olddir  = split '/', `readlink -q -m $params{'Old'}`;
  my @newdir  = split '/', `readlink -q -m $params{'New'}`;
  my @outdir  = @olddir;

  my $out = '';
  my $i;
  for ($i = 0; $i <= $#olddir && $i <= $#newdir; $i++) {
    $out++ if ($olddir[$i] ne $newdir[$i]);
    shift @outdir unless $out;
    unshift @outdir, ".." if $out;
  }
  if ($#newdir > $#olddir) {
    for ($i=0; $i < $#newdir; $i++) {
      unshift @outdir, "..";
    }
  }
  return join ('/', @outdir);
}
######################################################################
######################################################################
############
######################################################################
######################################################################


# This routine actually moves the kernel image
# From: $realimageloc/$kimage-$version (/boot/vmlinuz-2.6.12)
# To:   $image_dest/$kimage-$version   (/vmlinuz-2.6.12)
# Note that the image is moved to a versioned destination, but ordinary
# symlinks we create otherwise are not normally versioned
sub really_move_image {
  my $src_dir  = $_[0];
  my $target   = $_[1];
  my $dest_dir = $_[2];

  warn "Really move image: src_dir=$src_dir, target=$target,\n destdir=$dest_dir"
    if $DEBUG;
  if (-e "$target") {
    # we should be in dir $dest_dir == $image_dest /, normally
    rename("$target", "$target.$$") ||
      die "failed to move " . $dest_dir . "$target:$!";
    warn "mv $target $target.$$" if $DEBUG;
  }
  warn "mv -f $src_dir$target $target" if $DEBUG;
  my $ret = system("mv -f " . $src_dir . "$target " .
                   " $target");
  if ($ret) {
    die("Failed to move " . $src_dir . "$target to "
        . $dest_dir . "$target");
  }
  # Ok, now we may clobber the previous .old files
  if (-e "$target.$$") {
    rename("$target.$$", "$target.old") ||
      die "failed to move " . $dest_dir . "$target:$!";
    warn "mv $target.$$ $target " if $DEBUG;
  }
}

# Normally called after really_move_image; and only called if we asked for 
# reversed link this routine reverses the symbolic link that is notmally 
# created. Since the real kernel image has been moved over to 
# $image_dest/$kimage-$version. So, this routine links
# From:   $image_dest/$kimage-$version   (/vmlinuz-2.6.12)
# To:     $realimageloc/$kimage-$version (/boot/vmlinuz-2.6.12)
sub really_reverse_link {
  my $src_dir    = $_[0];
  my $link_name  = $_[1];
  my $dest_dir   = $_[2];
  warn "Really reverse link: src_dir=$src_dir, link name=$link_name\n" .
    "\tdestdir=$dest_dir" if $DEBUG;

  my $Old = $dest_dir;
  if (test_relative ('Old Dir' => $Old, 'New Dir' => $src_dir,
                     'Test File' => "$link_name")) {
    $Old   =~ s|^/*||o;
  }
  # Special case is they are in the same dir
  my $rel_path = spath('Old' => "$Old", 'New' => "$src_dir" );
  $Old ="" if $rel_path =~ m/^\s*$/o;

  if ($use_hard_links =~ m/YES/i) {
    link($Old . "$link_name", $src_dir . "$link_name") ||
      die("Failed to link " . $dest_dir . "$link_name to " . $src_dir . 
          "$link_name:$!");
    warn "ln " . $Old . "$link_name " . $src_dir . "$link_name"  if $DEBUG;
  }
  else {
    symlink($Old . "$link_name", $src_dir . "$link_name") ||
      die("Failed to symbolic-link " . $dest_dir . "$link_name to " . $src_dir
          . "$link_name:$!");
    warn "ln -s " . $Old . "$link_name " . $src_dir . "$link_name" if $DEBUG;
  }
}

# This routine is invoked if there is a symbolic link in place
# in $image_dest/$kimage -- so a symlink exists in the destination.
# What we are trying to determine is if we need to move the symbolic link over
# to the the .old location
sub move_p {
  my $kimage     = $_[0];       # Name of the symbolic link
  my $image_dest = $_[1];       # The directory the links goes into
  my $image_name = $_[2]; 
  my $src_dir    = $_[3]; 
  my $force_move = 0;
  warn "Move?: kimage=$kimage, image_dest=$image_dest, \n" .
    "\timage_name=$image_name, src_dir=$src_dir" if $DEBUG;

  if ($no_symlink || $reverse_symlink) {
    # we do not want links, yet we have a symbolic link here!
    warn "found a symbolic link in " . $image_dest . "$kimage \n" .
      "even though no_symlink is defined\n" if $no_symlink;
    warn "found a symbolic link in " . $image_dest . "$kimage \n" .
      "even though reverse_symlink is defined\n" if $reverse_symlink;
    # make sure we change this state of affairs
    $force_move = 1;
    return $force_move;
  }

  warn "DEBUG: OK. We found symlink, and we should have a symlink here.\n"
    if $DEBUG;
  my $vmlinuz_target = readlink "$kimage";
  my $real_target = '';
  my $target = `readlink -q -m "${realimageloc}${kimage}-${version}"`;
  $real_target = abs_path($vmlinuz_target) if defined($vmlinuz_target);

  if (!defined($vmlinuz_target) || ! -f "$real_target") {
    # what, a dangling symlink?
    warn "The link "  . $image_dest . "$kimage is a dangling link" .
      "to $real_target\n";
    $force_move = 1;
    return $force_move;
  }


  warn "DEBUG: The link $kimage points to ($vmlinuz_target)\n" if $DEBUG;
  warn "DEBUG: ($vmlinuz_target) is really ($real_target)\n" if $DEBUG;
  my $cwd;
  chomp ($cwd=`pwd`);
  if ($vmlinuz_target !~ m|^/|o) {
    $vmlinuz_target = $cwd . "/" . $vmlinuz_target;
    $vmlinuz_target =~ s|/+|/|o;
  }
  $vmlinuz_target = `readlink -q -m $vmlinuz_target`;

  if ("$vmlinuz_target" ne "$target") {
    warn "DEBUG: We need to handle this.\n" if $DEBUG;
    if ($minimal_swap) {
      warn "DEBUG: Minimal swap.\n" if $DEBUG;
      if (-l "$kimage.old") {
        warn "DEBUG: There is an old link at $kimage.old\n" if $DEBUG;
        my $old_target = readlink "$kimage.old";
        my $real_old_target = '';
        $real_old_target=abs_path($old_target) if defined ($old_target);

        if ($real_old_target  && -f "$real_old_target") {
          if ($old_target !~ m|^/|o) {
            $old_target = $cwd . "/" . $old_target;
            $old_target =~ s|/+|/|o;
          }
          $old_target = `readlink -q -m $old_target`;
          if ("$old_target"  ne "$target") {
            $force_move = 1;
            warn "DEBUG: Old link ($old_target) does not point to us ($target)\n"
              if $DEBUG;
          } 
          else {            # The .old points to the current
            warn "$kimage.old --> $target -- doing nothing";
            $force_move = 0;
          }
        } 
        else { 
          warn "DEBUG: Well, the old link does not exist -- so we move\n"
            if $DEBUG;
          $force_move = 1;
        }
      } 
      else {
        warn "DEBUG: No .old link -- OK to move\n"
          if $DEBUG;
        $force_move = 1;
      }
    } 
    else {
      warn "DEBUG: ok, minimal swap is no-- so we move.\n"
        if $DEBUG;
      $force_move = 1;
    }
  }
  else {                  # already have proper link
    warn "$kimage($vmlinuz_target) points to $target ($real_target) -- doing nothing";
    $force_move = 0;
  }
  return $force_move;
}


# This routine moves the symbolic link around (/vmlinuz -> /vmlinuz.old)
# It pays attention to whether we should the fact whether we should be using
# hard links or not.
sub really_move_link {
  my $kimage     = $_[0];       # Name of the symbolic link
  my $image_dest = $_[1];       # The directory the links goes into
  my $image_name = $_[2]; 
  my $src_dir    = $_[3]; 
  warn "really_move_link: kimage=$kimage, image_dest=$image_dest\n" .
    "\t image_name=$image_name, src_dir=$src_dir" if $DEBUG;

  # don't clobber $kimage.old quite yet
  rename("$kimage", "$kimage.$$") ||
    die "failed to move " . $image_dest . "$kimage:$!";
  warn "mv $kimage $kimage.$$" if $DEBUG;
  my $Old = $src_dir;
  my $cwd;

  chomp($cwd=`pwd`);
  if (test_relative ('Old Dir' => $Old, 'New Dir' => $cwd,
                     'Test File' => "$image_name")) {
    $Old   =~ s|^/*||o;
  }
  # Special case is they are in the same dir
  my $rel_path = spath('Old' => "$Old", 'New' => "$cwd" );
  $Old ="" if $rel_path =~ m/^\s*$/o;

  if ($use_hard_links =~ m/YES/i) {
    warn "ln ${Old}${image_name} $kimage" if $DEBUG;
    if (! link("${Old}${image_name}", "$kimage")) {
      rename("$kimage.$$", "$kimage");
      die("Failed to link ${Old}${image_name} to " .
          "${image_dest}${kimage}:$!");
    }
  } 
  else {
    warn "ln -s ${Old}${image_name} $kimage" if $DEBUG;
    if (! symlink("${Old}${image_name}", "$kimage")) {
      rename("$kimage.$$", "$kimage");
      die("Failed to symbolic-link ${Old}${image_name} to " .
          "${image_dest}${kimage}:$!");
    }
  }

  # Ok, now we may clobber the previous .old file
  if (-l "$kimage.old" || ! -e "$kimage.old" ) {
    rename("$kimage.$$", "$kimage.old");
    warn "mv $kimage.$$ $kimage.old" if $DEBUG;
  }
  else {
    warn "$kimage.old is not a symlink, not clobbering\n";
    warn "rm $kimage.$$";
    unlink "$kimage.$$" if $DEBUG;
  }
}

# This routine handles a request to do symlinks, but there is no
# symlink file already there.  Either we are supposed to use copy, or we are
# installing on a pristine system, or the user does not want symbolic links at
# all.  We use a configuration file to tell the last two cases apart, creating
# a config file if needed.
sub handle_missing_link {
  my $kimage     = $_[0];       # Name of the symbolic link
  my $image_dest = $_[1];       # The directory the links goes into
  my $image_name = $_[2]; 
  my $src_dir    = $_[3]; 
  warn "handle_missing_link: kimage=$kimage, image_dest=$image_dest\n" .
    "\t image_name=$image_name, src_dir=$src_dir" if $DEBUG;

  if ($no_symlink) {
    warn "cp -a --backup=t $realimageloc$image_name $kimage" if $DEBUG;
    my $ret = system("cp -a --backup=t " . $realimageloc .
                     "$image_name "   . " $kimage");
    if ($ret) {
      die("Failed to copy " . $realimageloc . "$image_name to "
          . $image_dest . "$kimage");
    }
  } 
  elsif ($reverse_symlink) {
    warn "mv -f $realimageloc$image_name $kimage" if $DEBUG;
    my $ret = system("mv -f " . $realimageloc . "$image_name "
                     . "$kimage");
    if ($ret) {
      die("Failed to move " . $realimageloc . "$image_name to "
          . $image_dest . "$kimage");
    }
  } 
  else {
    if (! $have_conffile) {
      my $ret;
      my $answer='';
      $do_symlink = "Yes";

      if (open(CONF, ">$CONF_LOC")) {
        print CONF "# Kernel Image management overrides\n";
        print CONF "# See kernel-img.conf(5) for details\n";
        if ($loader =~ /palo/i) {
          print CONF "link_in_boot = Yes\n";
          print CONF "do_symlinks = Yes\n";
          print CONF "relative_links = Yes\n";
          print CONF "do_bootloader = No\n";
        } else {
          print CONF "do_symlinks = $do_symlink\n";
        }
        close CONF;
      }
      $have_conffile = "Yes";
    }
  }

  if (! $no_symlink && $do_symlink =~ /Yes/i) {
    my $Old = $realimageloc;
    my $New = $image_dest;
    my $Name = "$image_name";
    my $Link_Dest = "$kimage";

    if ($reverse_symlink) {
      $Old = $image_dest;
      $New = $realimageloc;
      $Name = "$kimage";
      $Link_Dest = $realimageloc . "$image_name";
    }
    if (test_relative ('Old Dir' => $Old,
                       'New Dir' => $New,
                       'Test File' => $Name)) {
      $Old   =~ s|^/*||o;
    }
    # Special case is they are in the same dir
    my $rel_path = spath('Old' => "$Old", 'New' => "$New" );
    $Old ="" if $rel_path =~ m/^\s*$/o;

    symlink($Old . "$Name", "$Link_Dest") ||
      die("Failed to symbolic-link ${Old}$Name to $Link_Dest:$!");
    warn "ln -s ${Old}$Name $Link_Dest" if $DEBUG;

  }
}

# This routine handles the rest of the cases, where the user has requested 
# non-traditional handling, like using cp, or reverse symlinks, or hard links.
sub handle_non_symlinks {
  my $kimage     = $_[0];       # Name of the symbolic link
  my $image_dest = $_[1];       # The directory the links goes into
  my $image_name = $_[2]; 
  my $src_dir    = $_[3]; 
  warn "handle_non_link: kimage=$kimage, image_dest=$image_dest\n" .
    "\t image_name=$image_name, src_dir=$src_dir" if $DEBUG;

  # Save the current image. We do this in all four cases
  rename("$kimage", "$kimage.$$") || 
    die "failed to move " . $image_dest . "$kimage:$!";
  warn "mv $kimage $kimage.$$" if $DEBUG;

  ##,#### 
  # case One
  #`####
  if ($no_symlink) {
    # Maybe /$image_dest is on a dos system?
    warn "cp -a --backup=t $realimageloc$image_name $kimage" if $DEBUG;
    my $ret = system("cp -a --backup=t " . $realimageloc
                     . "$image_name " . "$kimage");
    if ($ret) {
      if (-e "$kimage.$$") {
        rename("$kimage.$$", "$kimage");
        warn "mv $kimage.$$ $kimage" if $DEBUG;
      }
      die("Failed to copy " . $realimageloc . "$image_name to "
          . $image_dest . "$kimage");
    }
  }
  ##,#### 
  # case Two
  #`####
  elsif ($reverse_symlink) {  # Maybe /$image_dest is on a dos system?
    warn "mv -f  $realimageloc$image_name $kimage" if $DEBUG;
    my $ret = system("mv -f " . $realimageloc . "$image_name "
                     . $image_dest . "$kimage");
    if ($ret) {
      if (-e "$kimage.$$") {
        rename("$kimage.$$", "$kimage");
        warn "mv $kimage.$$ $kimage" if $DEBUG;
      }
      die("Failed to move " . $realimageloc . "$image_name to "
          . $image_dest . "$kimage");
    }
    my $Old = $image_dest;
    if (test_relative ('Old Dir' => $Old, 'New Dir' => $realimageloc,
                       'Test File' => "$kimage")) {
      $Old   =~ s|^/*||o;
    }
    # Special case is they are in the same dir
    my $rel_path = spath('Old' => "$Old", 'New' => "$realimageloc" );
    $Old ="" if $rel_path =~ m/^\s*$/o;

    if ($use_hard_links =~ m/YES/i) {
      warn "ln " . $Old . "$kimage " . $realimageloc . "$image_name" if $DEBUG;
      if (! link($Old . "$kimage", $realimageloc . "$image_name")) {
        warn "Could not link " . $image_dest .
          "$kimage to $image_name :$!";
      }
    }
    else {
      warn "ln -s " . $Old . "$kimage " . $realimageloc . "$image_name" if $DEBUG;
      if (! symlink($Old . "$kimage", $realimageloc . "$image_name")) {
        warn "Could not symlink " . $image_dest .
          "$kimage to $image_name :$!";
      }
    }
  }
  ##,####
  # case Three
  #`####
  elsif ($use_hard_links =~ m/YES/i ) {
    # Ok then. this ought to be a hard link, and hence fair game
    # don't clobber $kimage.old quite yet
    my $Old = $realimageloc;
    my $cwd;
    chomp($cwd=`pwd`);
    if (test_relative ('Old Dir' => $Old, 'New Dir' => $cwd,
                       'Test File' => "$image_name")) {
      $Old   =~ s|^/*||o;
    }
    # Special case is they are in the same dir
    my $rel_path = spath('Old' => "$Old", 'New' => "$cwd" );
    $Old ="" if $rel_path =~ m/^\s*$/o;

    warn "ln " . $Old . "$image_name " . "$kimage" if $DEBUG;
    if (! link($Old . "$image_name", "$kimage")) {
      warn "mv $kimage.$$ $kimage" if $DEBUG;
      rename("$kimage.$$", "$kimage");
      die("Failed to link " . $realimageloc . "$image_name to "
          . $image_dest . "$kimage");
    }
  }
  ##,####
  # case Five!?!
  #`####
  elsif ($do_symlink) {
    # Ok then. this ought to be a symlink, and hence fair game
    # don't clobber $kimage.old quite yet
    my $Old = $realimageloc;
    my $cwd;
    chomp($cwd=`pwd`);
    if (test_relative ('Old Dir' => $Old, 'New Dir' => $cwd,
                       'Test File' => "$image_name")) {
      $Old   =~ s|^/*||o;
    }
    # Special case is they are in the same dir
    my $rel_path = spath('Old' => "$Old", 'New' => "$cwd" );
    $Old ="" if $rel_path =~ m/^\s*$/o;

    warn "symlink " . $Old . "$image_name " . "$kimage" if $DEBUG;
    if (! symlink($Old . "$image_name", "$kimage")) {
      warn "mv $kimage.$$ $kimage" if $DEBUG;
      rename("$kimage.$$", "$kimage");
      die("Failed to link " . $realimageloc . "$image_name to "
          . $image_dest . "$kimage");
    }
  }
  ##,####
  # case Four
  #`####
  else {
    # We just use cp
    warn "cp -a --backup=t $realimageloc$image_name $kimage" if $DEBUG;
    my $ret = system("cp -a --backup=t " . $realimageloc
                     . "$image_name " . "$kimage");
    if ($ret) {
      if (-e "$kimage.$$") {
        warn "mv $kimage.$$ $kimage" if $DEBUG;
        rename("$kimage.$$", "$kimage");
      }
      die("Failed to copy " . $realimageloc . "$image_name to "
          . $image_dest . "$kimage");
    }
  }
  # Ok, now we may clobber the previous .old file
  warn "mv $kimage.$$ $kimage.old if -e $kimage.$$" if $DEBUG;
  rename("$kimage.$$", "$kimage.old") if -e "$kimage.$$";
}

# This routine is responsible for setting up the symbolic links
# So, the actual kernel image lives in
# $realimageloc/$image_name (/boot/vmlinuz-2.6.12).
# This routine creates symbolic links in $image_dest/$kimage (/vmlinuz)
sub image_magic {
  my $kimage     = $_[0];       # Name of the symbolic link
  my $image_dest = $_[1];       # The directory the links goes into
  my $image_name = "$kimage-$version";
  my $src_dir    = $realimageloc;
  warn "image_magic: kimage=$kimage, image_dest=$image_dest\n" .
    "\t image_name=$image_name, src_dir=$src_dir" if $DEBUG;

  # Well, in any case, if the destination (the symlink we are trying
  # to create) is a directory, we should do nothing, except throw a
  # diagnostic.
  if (-d "$kimage" ) {
    die ("Hmm. $kimage is a directory, which I did not expect.  I am\n" .
         "trying to create a symbolic link with that name linked to \n" .
         "$image_dest . Since a directory exists here, my assumptions \n" .
         "are way off, and I am aborting.\n" );
    exit (3);
  }

  if ($move_image) {   # Maybe $image_dest is in on dos, or something?
    #                   source dir,    link name,        dest dir
    really_move_image(  $realimageloc, $image_name, $image_dest);
    really_reverse_link($realimageloc, $image_name, $image_dest)
      if $reverse_symlink;
    return;
  }

  if (-l "$kimage") {           # There is a symbolic link
    warn "DEBUG: There is a symlink for $kimage\n" if $DEBUG;
    my $force_move = move_p($kimage, $image_dest, $image_name, $src_dir);

    if ($force_move) {
      really_move_link($kimage, $image_dest, $image_name, $src_dir);
    }
  }
  elsif (! -e "$kimage") {
    # Hmm. Pristine system? How can that be? Installing from scratch?
    # Or maybe the user does not want a symbolic link here.
    # Possibly they do not want a link here. (we should be in /
    # here[$image_dest, really]
    handle_missing_link($kimage, $image_dest, $image_name, $src_dir);
  }
  elsif (-e "$kimage" ) {
    # OK, $kimage exists -- but is not a link
    handle_non_symlinks($kimage, $image_dest, $image_name, $src_dir);
  }
}

######################################################################
######################################################################
######################################################################
######################################################################

# We may not have any modules installed
if ( -d "$modules_base/$version" ) {
  print STDERR "Running depmod.\n";
  my $ret = system("depmod -a $version");
  if ($ret) {
    print STDERR "Failed to run depmod\n";
    exit(1);
  }
}



sub find_initrd_tool {
  my $hostversion = shift;
  my $version = shift;
  print STDERR "Finding valid ramdisk creators.\n";
  my @ramdisks =
    grep {
      my $args = 
        "$_ " .
          "--supported-host-version=$hostversion " .
            "--supported-target-version=$version " .
              "1>/dev/null 2>&1"
                ;
      system($args) == 0;
    }
      split (/[:,\s]+/, $ramdisk);
}

# The initrd symlink should probably be in the same dir that the
# symlinks are in
if ($initrd) {
  my $success = 0;

  # Update-initramfs is called slightly different than mkinitrd and
  # mkinitramfs. XXX It should really be made compatible with this stuff
  # some how.
  my $upgrading = 1;
  if (! defined $ARGV[1] || ! $ARGV[1] || $ARGV[1] =~ m/<unknown>/og) {
    $upgrading = 0;
  }
  my $ret = system("$ramdisk " . ($upgrading ? "-u" : "-c") . " -k " . $version . " >&2");
  $success = 1 unless $ret;
  die "Failed to create initrd image.\n" unless $success;
  if (! defined $ARGV[1] || ! $ARGV[1] || $ARGV[1] =~ m/<unknown>/og) {
    image_magic("initrd.img", $image_dest);
  }
  else {
    lstat("initrd.img");
    if (! -e _) {
      handle_missing_link("initrd.img", $image_dest, "initrd.img-$version",
                          $realimageloc);
    }
    else {
      print STDERR
        "Not updating initrd symbolic links since we are being updated/reinstalled \n";
      print STDERR
        "($ARGV[1] was configured last, according to dpkg)\n";
    }
  }

  if ($initrd && -l "initrd" ) {
    unlink "initrd";
  }

  if ($initrd && -l "$image_dir/initrd" && ! $link_in_boot) {
    unlink "$image_dir/initrd";
  }
}
else {                        # Not making an initrd emage
  if (-l "initrd.img") {
    # Ooh, last image was an initrd image? in any case, we should move it. 
    my $target = readlink "initrd.img";
    my $real_target = '';
    $real_target = abs_path($target) if defined ($target);

    if (!defined($target) || ! -f "$real_target") {
      # Eh. dangling link. can safely be removed.
      unlink("initrd.img");
    } else {
      if (-l "initrd.img.old" || ! -e "initrd.img.old" ) {
        rename("initrd.img", "initrd.img.old");
      } else {
        warn "initrd.img.old is not a symlink, not clobbering\n";
        unlink("initrd.img");
      }
    }
  }
}

# Warn of a reboot
if (-x $notifier) {
  system($notifier);
}

# Let programs know not to hibernate if the kernel that would be used for
# resume-from-hibernate is likely to differ from the currently running kernel.
system("mountpoint -q /var/run");
if ($? eq 0) {
	system("touch /var/run/do-not-hibernate");
}

# Only change the symlinks if we are not being upgraded
if (! defined $ARGV[1] || ! $ARGV[1] || $ARGV[1] =~ m/<unknown>/og) {
  image_magic($kimage, $image_dest);
}
else {
  lstat("$kimage");
  if (! -e _) {
    handle_missing_link($kimage, $image_dest, "$kimage-$version", 
                        $realimageloc);
  }
  else {
    print STDERR
      "Not updating image symbolic links since we are being updated/reinstalled \n";
    print STDERR
      "($ARGV[1] was configured last, according to dpkg)\n";
  }
}

# We used to have System.* files in /
if (-e "/System.map" || -e "/System.old") {
  unlink '/System.map' if -e '/System.map';
  unlink '/System.old' if -e '/System.old';
}

# creating some info about kernel and initrd
if ($DEBUG) {
  my $ksize=sprintf("%.0f",(stat($realimageloc .
                                 "$kimage-$version"))[7]/1024)."kB";
  my $initrdsize='';
  if ($initrd) {
    $initrdsize=sprintf("%.0f",(stat($realimageloc .
                                     "initrd.img-$version"))[7]/1024)."kB";
  }

  print STDERR <<"EOMSG";
A new kernel image has been installed at $realimageloc$kimage-$version
 (Size: $ksize)

Symbolic links, unless otherwise specified, can be found in $image_dest

EOMSG
  ;

  if ($initrd) {
    print STDERR <<"EOMSGA";

 Initial rootdisk image: ${realimageloc}initrd.img-$version (Size: $initrdsize)
EOMSGA
    ;
  }
}

# set the env var stem
$ENV{'STEM'} = "linux";
sub exec_script {
  my $type   = shift;
  my $script = shift;
  print STDERR "Running $type hook script $script.\n";
  system ("$script $version $realimageloc$kimage-$version") &&
    print STDERR "User $type hook script [$script] ";
  if ($?) {
    if ($? == -1) {
      print STDERR "failed to execute: $!\n";
    }
    elsif ($? & 127) {
      printf STDERR "died with signal %d, %s coredump\n",
        ($? & 127),  ($? & 128) ? 'with' : 'without';
    }
    else {
      printf STDERR "exited with value %d\n", $? >> 8;
    }
    exit $? >> 8;
  }
}
sub run_hook {
  my $type   = shift;
  my $script = shift;
  if ($script =~ m,^/,) {
    # Full path provided for the hook script
    if (-x "$script") {
      &exec_script($type,$script);
    }
    else {
      die "The provided $type hook script [$script] could not be run.\n";
    }
  }
  else {
    # Look for it in a safe path
    for my $path ('/bin', '/sbin', '/usr/bin', '/usr/sbin') {
      if (-x "$path/$script") {
        &exec_script($type, "$path/$script");
        return 0;
      }
    }
    # No luck
    print STDERR "Could not find $type hook script [$script].\n";
    die "Looked in: '/bin', '/sbin', '/usr/bin', '/usr/sbin'\n";
  }
}

my $options;
for (@ARGV) {
	s,','\\'',g;
	$options .= " '$_'";
}
$ENV{'DEB_MAINT_PARAMS'}="$options";

## Run user hook script here, if any
if ($postinst_hook) {
  &run_hook("postinst", $postinst_hook);
}

if (-d "/etc/kernel/postinst.d") {
  print STDERR "Examining /etc/kernel/postinst.d.\n";
  system ("run-parts --verbose --exit-on-error --arg=$version " .
          "--arg=$realimageloc$kimage-$version " .
          "/etc/kernel/postinst.d") &&
            die "Failed to process /etc/kernel/postinst.d";
}

if (-d "/etc/kernel/postinst.d/$version") {
  print STDERR "Examining /etc/kernel/postinst.d/$version.\n";
  system ("run-parts --verbose --exit-on-error --arg=$version " .
          "--arg=$realimageloc$kimage-$version " .
          "/etc/kernel/postinst.d/$version") &&
            die "Failed to process /etc/kernel/postinst.d/$version";
}

LOADER: {
  last unless $do_boot_enable; # Exit if explicitly asked to

  last if $loader =~ /silo/i; # SILO does not have to be executed.
  last if $loader =~ /yaboot/i; # yaboot does not have to be executed.
  last if $loader =~ /milo/i; # MILO does not have to be executed.
  last if $loader =~ /nettrom/i; # NETTROM does not have to be executed.
  last if $loader =~ /arcboot/i; # ARCBOOT does not have to be executed.
  last if $loader =~ /delo/i; # DELO does not have to be executed.
  last if $loader =~ /quik/i; # maintainer asked quik invocation to be ignored

  last unless $loaderloc;
  last unless -x $loaderloc;
  last unless $do_bootloader;

  if (-T "/etc/$loader.conf") {
    # Trust and use the existing lilo.conf.
    print STDERR "You already have a $Loader configuration in /etc/$loader.conf\n";
    my $ret = &run_lilo();
    exit $ret if $ret;
  }
}


sub run_lilo (){
  my $ret;
  # Try and figure out if the user really wants lilo to be run --
  # since the default is to run the boot laoder, which is ! grub -- but
  # the user may be using grub now, and not changed the default.

  # So, if the user has explicitly asked for the loader to be run, or
  # if there is no postinst hook, or if there is no grub installed --
  # we are OK. Or else, we ask.
  if ($explicit_do_loader || (! ($postinst_hook && -x '/usr/sbin/grub')))  {
    print STDERR "Running boot loader as requested\n";
  } else {
    print STDERR "Ok, not running $loader\n";
  }
  if ($loader =~ /^lilo/io or $loader =~ /vmelilo/io) {
    print STDERR "Testing $loader.conf ... \n";
    unlink $temp_file_name;     # security
    $ret = system("$loaderloc -t >$temp_file_name 2>&1");
    if ($ret) {
      print STDERR "Boot loader test failed\n";
      return $ret;
    }
    unlink "$temp_file_name";
    print STDERR "Testing successful.\n";
    print STDERR "Installing the ";
    print STDERR "partition " if $loader =~ /^lilo/io;
    print STDERR "boot sector... \n";
  }

  print STDERR "Running $loaderloc  ... \n";
  if ($loader =~ /^elilo/io) {
    $ret = system("$loaderloc 2>&1 | tee $temp_file_name");
  } else {
    $ret = system("$loaderloc >$temp_file_name 2>&1");
  }
  if ($ret) {
    print STDERR "Boot loader failed to run\n";
    return $ret;
  }
  unlink $temp_file_name;
  print STDERR "Installation successful.\n";
  return 0;
}

exit 0;

__END__
linux-image-4.15.0-13-lowlatency 4.15.0-13.14~16.04.1 / postinst
