Merge pull request #49 from glasswalk3r/refactor/ubuntu-without-exec

refactor: replaced system exec

lib/Devel/AssertOS/Linux/Ubuntu.pm

@@ -3,18 +3,21 @@ package Devel::AssertOS::Linux::Ubuntu;
 use Devel::CheckOS;
 use strict;
 use warnings;
+
+use Devel::AssertOS::OSFeatures::Release 'distributor_id';
+
 no warnings 'redefine';
 
-our $VERSION = '1.0';
+our $VERSION = '1.1';
 
 sub os_is {
-    Devel::CheckOS::os_is('Linux') &&
-    `lsb_release -i 2>/dev/null` =~ /Ubuntu/
+    my $id = distributor_id;
+    Devel::CheckOS::os_is('Linux') && defined($id) && $id =~ /Ubuntu/;
 }
 
 sub expn { "The operating system is some version of Ubuntu" }
 
-Devel::CheckOS::die_unsupported() unless(os_is());
+Devel::CheckOS::die_unsupported() unless ( os_is() );
 
 =head1 COPYRIGHT and LICENCE
 

lib/Devel/AssertOS/OSFeatures/Release.pm

@@ -0,0 +1,83 @@
+package Devel::AssertOS::OSFeatures::Release;
+
+use strict;
+use warnings;
+use File::Spec;
+use parent 'Exporter';
+
+our $VERSION   = '1.0';
+our @EXPORT_OK = qw(distributor_id);
+
+=pod
+
+=head1 NAME
+
+Devel::AssertOS::OSFeatures::Release - functions to manipulate os-release file
+
+=head1 SYNOPSIS
+
+    use Devel::AssertOS::OSFeatures::Release 'distributor_id';
+    my $id = distributor_id;
+
+=head1 DESCRIPTION
+
+This module exports functions to handle text files related to Debian-like
+distributions.
+
+=head1 EXPORTED
+
+The following subs are exported.
+
+=head2 distributor_id
+
+Retrieves and returns the distributor ID from the F</etc/os-release> file.
+
+It is expected that the file exists, it is readable and have the following
+(minimum) content format:
+
+    NAME="Ubuntu"
+    VERSION_ID="22.04"
+    VERSION="22.04.4 LTS (Jammy Jellyfish)"
+    VERSION_CODENAME=jammy
+    ID=ubuntu
+    ID_LIKE=debian
+    HOME_URL="https://www.ubuntu.com/"
+
+This excerpt is from Ubuntu 22.04, but other distributions might have fewer,
+more or different fields and values.
+
+It returns the value of C<ID> or C<undef>, if the conditions are not those
+specified above.
+
+=cut
+
+sub distributor_id {
+    my $filename  = 'os-release';
+    my $file_path = File::Spec->catfile( ( '', 'etc' ), $filename );
+    my $regex     = qr/^ID\=(\w+)/;
+    my $dist_id   = undef;
+
+    if ( -r $file_path ) {
+        open my $in, '<', $file_path or die "Cannot read $file_path: $!";
+        while (<$in>) {
+            chomp;
+            if ( $_ =~ $regex ) {
+                $dist_id = ucfirst(lc $1) if (defined($1));
+                last;
+            }
+        }
+        close($in) or die "Cannot close $file_path: $!";
+    }
+
+    return $dist_id;
+}
+
+=head1 COPYRIGHT and LICENCE
+
+Copyright 2024 David Cantrell
+
+This software is free-as-in-speech software, and may be used, distributed, and modified under the terms of either the GNU General Public Licence version 2 or the Artistic Licence. It's up to you which one you use. The full text of the licences can be found in the files GPL2.txt and ARTISTIC.txt, respectively.
+
+=cut
+
+1;

t/os-release.t

@@ -0,0 +1,17 @@
+use warnings;
+use strict;
+use Test::More;
+use Devel::AssertOS::OSFeatures::Release 'distributor_id';
+
+my $total_tests = 3;
+plan tests => $total_tests;
+
+SKIP: {
+    skip 'Not a Linux distribution', $total_tests unless ( $^O eq 'linux' );
+    my $id = distributor_id();
+    ok( $id, 'can fetch the distribution ID' )
+      or BAIL_OUT('No use to keep testing with ID = undef');
+    like $id, qr/^\w+$/, 'ID looks like a string';
+    my $copy = ucfirst( lc $id );
+    is( $id, $copy, 'ID is returned with first character in uppercase' );
+}