scripts/Dpkg/Lock.pm

   1 # Copyright © 2011 Raphaël Hertzog <hertzog@debian.org>
   2 # Copyright © 2012 Guillem Jover <guillem@debian.org>
   3 #
   4 # This program is free software; you can redistribute it and/or modify
   5 # it under the terms of the GNU General Public License as published by
   6 # the Free Software Foundation; either version 2 of the License, or
   7 # (at your option) any later version.
   8 #
   9 # This program is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 # GNU General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU General Public License
  15 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
  16
  17 =encoding utf8
  18
  19 =head1 NAME
  20
  21 Dpkg::Lock - file locking support
  22
  23 =head1 DESCRIPTION
  24
  25 This module implements locking functions used to support parallel builds.
  26
  27 B<Note>: This is a private module, its API can change at any time.
  28
  29 =cut
  30
  31 package Dpkg::Lock 0.01;
  32
  33 use strict;
  34 use warnings;
  35
  36 our @EXPORT = qw(
  37     file_lock
  38 );
  39
  40 use Exporter qw(import);
  41 use Fcntl qw(:flock);
  42
  43 use Dpkg::Gettext;
  44 use Dpkg::ErrorHandling;
  45
  46 sub file_lock($$) {
  47     my ($fh, $filename) = @_;
  48
  49     # A strict dependency on libfile-fcntllock-perl being it an XS module,
  50     # and dpkg-dev indirectly making use of it, makes building new perl
  51     # package which bump the perl ABI impossible as these packages cannot
  52     # be installed alongside.
  53     eval q{
  54         use File::FcntlLock;
  55     };
  56     if ($@) {
  57         # On Linux systems the flock() locks get converted to file-range
  58         # locks on NFS mounts.
  59         if ($^O ne 'linux') {
  60             warning(g_('File::FcntlLock not available; using flock which is not NFS-safe'));
  61         }
  62         flock($fh, LOCK_EX)
  63             or syserr(g_('failed to get a write lock on %s'), $filename);
  64     } else {
  65         eval q{
  66             my $fs = File::FcntlLock->new(l_type => F_WRLCK);
  67             $fs->lock($fh, F_SETLKW)
  68                 or syserr(g_('failed to get a write lock on %s'), $filename);
  69         }
  70     }
  71 }
  72
  73 =head1 CHANGES
  74
  75 =head2 Version 0.xx
  76
  77 This is a private module.
  78
  79 =cut
  80
  81 1;