relocatable-perl module

[Reuben Thomas]

The attached patch adds a module relocatable-perl that does for Perl
scripts what relocatable-script does for shell scripts.

(In a previous message, I pointed out that relocatable-script can be
used for Perl. While this is true, it's a somewhat delicate hack,
requires an extra fork, and doesn't work on systems that lack a shell.
The Perl code is also rather shorter and probably more robust.)

Patch follows:

From: Reuben Thomas <address@hidden>
Date: Tue, 31 Dec 2013 22:42:39 +0000
Subject: [PATCH] relocatable-perl: like relocatable-script, but for Perl
 scripts

* build-aux/relocatable.pl.in: Add.
* doc/relocatable-maint.texi: Add documentation.
* modules/relocatable-perl: Add.
---
 ChangeLog                   |  7 +++++
 build-aux/relocatable.pl.in | 64 +++++++++++++++++++++++++++++++++++++++++++++
 doc/relocatable-maint.texi  | 22 ++++++++++++++++
 modules/relocatable-perl    | 26 ++++++++++++++++++
 4 files changed, 119 insertions(+)
 create mode 100644 build-aux/relocatable.pl.in
 create mode 100644 modules/relocatable-perl

diff --git a/ChangeLog b/ChangeLog
index 36ede18..f6851d2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2013-12-31  Reuben Thomas  <address@hidden>
+
+       relocatable-perl: like relocatable-script, but for Perl scripts
+       * build-aux/relocatable.pl.in: Add.
+       * doc/relocatable-maint.texi: Add documentation.
+       * modules/relocatable-perl: Add.
+
 2013-12-24  Eric Blake  <address@hidden>
 
        passfd: give nicer error for recvfd at eof
diff --git a/build-aux/relocatable.pl.in b/build-aux/relocatable.pl.in
new file mode 100644
index 0000000..5472468
--- /dev/null
+++ b/build-aux/relocatable.pl.in
@@ -0,0 +1,64 @@
+# The functions in this file provide support for relocatability of
+# Perl scripts.  They should be included near the beginning of each
+# Perl script in a relocatable program, by adding @relocatable_pl@
+# and causing the script to be expanded with AC_CONFIG_FILES.  A
+# small amount of additional code must be added and adapted to the
+# package by hand; see doc/relocatable-maint.texi (in Gnulib) for
+# details.
+#
+# This code is based on relocatable.sh.in, and design changes (and
+# bugs) should probably be cross-checked with it.
+#
+# Copyright (C) 2013 Free Software Foundation, Inc.
+#
+# 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 3 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, see <http://www.gnu.org/licenses/>.
+#
+
+use Config;
+use File::Basename;
+use File::Spec::Functions;
+use Cwd 'realpath';
+
+# Support for relocatability.
+sub find_curr_installdir {
+  # Determine curr_installdir, even taking into account symlinks.
+  my $curr_executable = $0;
+  my $basename = basename($0);
+  if ($curr_executable eq $basename) {
+    LOOP: for my $dir (split /$Config{path_sep}/, $ENV{PATH}) {
+      $dir = "." unless $dir;
+      for my $ext ('') {
+        my $filename = catfile($dir, "$curr_executable$ext");
+        if (-f $filename) {
+          $curr_executable = $filename;
+          last LOOP;
+        }
+      }
+    }
+  }
+  # Resolve symlinks and canonicalize.
+  return realpath(dirname($curr_executable));
+}
+sub find_prefixes {
+  # Compute the original/current installation prefixes by stripping the
+  # trailing directories off the original/current installation directories.
+  my ($orig_installprefix, $curr_installprefix) = @_;
+  my $orig_last = basename($orig_installprefix);
+  my $curr_last = basename($curr_installprefix);
+  if ($orig_last && $curr_last && $orig_last eq $curr_last) {
+    $orig_installprefix = dirname($orig_installprefix);
+    $curr_installprefix = dirname($curr_installprefix);
+  }
+  return $orig_installprefix, $curr_installprefix;
+}
diff --git a/doc/relocatable-maint.texi b/doc/relocatable-maint.texi
index 8780b84..6edd62b 100644
--- a/doc/relocatable-maint.texi
+++ b/doc/relocatable-maint.texi
@@ -135,6 +135,28 @@ where the script gets installed.  Also, at the end, 
instead of
 @code{gettext_dir}, transform those variables that you need.
 
 @item
+If your package installs Perl scripts, also import the
address@hidden module.  Then, near the beginning of each
+Perl script that your package installs, add the following:
+
address@hidden
+@@relocatable_pl@@
+if ("@@RELOCATABLE@@" eq "yes") {
+  my $exec_prefix = "@@exec_prefix@@";
+  my $orig_installdir = "@@bindir@@"; # see Makefile.am's *_SCRIPTS variables
+  my ($orig_installprefix, $curr_installprefix) = 
find_prefixes($orig_installdir, find_curr_installdir());
+  # Relocate the directory variables that we use.
+  $gettext_dir = "@@gettext_dir@@";
+  $gettext_dir =~ s%^$orig_installprefix/%$curr_installprefix/%;
+  $gettext_dir =~ s,/$,,;
+}
address@hidden example
+
+You must adapt the definition of @code{$orig_installdir}, depending on
+where the script gets installed.  Also, at the end, instead of
address@hidden, transform those variables that you need.
+
address@hidden
 In your @file{Makefile.am}, for every program @command{foo} that gets
 installed in, say, @file{$(bindir)}, you add:
 
diff --git a/modules/relocatable-perl b/modules/relocatable-perl
new file mode 100644
index 0000000..42498e2
--- /dev/null
+++ b/modules/relocatable-perl
@@ -0,0 +1,26 @@
+Description:
+Help make Perl scripts relocatable, that is, to allow them to
+function properly when copied to an arbitrary directory.
+
+Files:
+doc/relocatable.texi
+build-aux/relocatable.pl.in
+m4/relocatable-lib.m4
+
+Depends-on:
+
+configure.ac:
+AC_REQUIRE([gl_RELOCATABLE_NOP])
+relocatable_pl=$ac_aux_dir/relocatable.pl.in
+AC_SUBST_FILE([relocatable_pl])
+
+Makefile.am:
+
+Include:
+
+License:
+GPL
+
+Maintainer:
+Bruno Haible, Ben Pfaff
+
-- 
1.8.3.2

-- 
http://rrt.sc3d.org/