build-aux/relocatable.pl.in

   1 # The functions in this file provide support for relocatability of
   2 # Perl scripts.  They should be included near the beginning of each
   3 # Perl script in a relocatable program, by adding @relocatable_pl@
   4 # and causing the script to be expanded with AC_CONFIG_FILES.  A
   5 # small amount of additional code must be added and adapted to the
   6 # package by hand; see doc/relocatable-maint.texi (in Gnulib) for
   7 # details.
   8 #
   9 # This code is based on relocatable.sh.in, and design changes (and
  10 # bugs) should probably be cross-checked with it.
  11 #
  12 # Copyright (C) 2013, 2015-2018 Free Software Foundation, Inc.
  13 #
  14 # This program is free software: you can redistribute it and/or modify
  15 # it under the terms of the GNU General Public License as published by
  16 # the Free Software Foundation; either version 3 of the License, or
  17 # (at your option) any later version.
  18 #
  19 # This program is distributed in the hope that it will be useful,
  20 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  21 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22 # GNU General Public License for more details.
  23 #
  24 # You should have received a copy of the GNU General Public License
  25 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
  26 #
  27
  28 use Config;
  29 use File::Basename;
  30 use File::Spec::Functions;
  31 use Cwd 'realpath';
  32
  33 # Support for relocatability.
  34 sub find_curr_installdir {
  35   # Determine curr_installdir, even taking into account symlinks.
  36   my $curr_executable = $0;
  37   my $basename = basename($0);
  38   if ($curr_executable eq $basename) {
  39     LOOP: for my $dir (split /$Config{path_sep}/, $ENV{PATH}) {
  40       $dir = "." unless $dir;
  41       for my $ext ('') {
  42         my $filename = catfile($dir, "$curr_executable$ext");
  43         if (-f $filename) {
  44           $curr_executable = $filename;
  45           last LOOP;
  46         }
  47       }
  48     }
  49   }
  50   # Resolve symlinks and canonicalize.
  51   return realpath(dirname($curr_executable));
  52 }
  53 sub find_prefixes {
  54   # Compute the original/current installation prefixes by stripping the
  55   # trailing directories off the original/current installation directories.
  56   my ($orig_installprefix, $curr_installprefix) = @_;
  57   my $orig_last = basename($orig_installprefix);
  58   my $curr_last = basename($curr_installprefix);
  59   if ($orig_last && $curr_last && $orig_last eq $curr_last) {
  60     $orig_installprefix = dirname($orig_installprefix);
  61     $curr_installprefix = dirname($curr_installprefix);
  62   }
  63   return $orig_installprefix, $curr_installprefix;
  64 }