can_write_dir.t and Packlist.t fail within AFS filesystem

[djzhh]

can_write_dir.t and Packlist.t fail when Perl is compiled within AFS filesystem (perl-5.38.2 and perl-5.36.3) but works fine within the local filesystem:

1. can_write_dir.t:

cpan/ExtUtils-Install/t/can_write_dir ............................ 
#   Failed test at t/can_write_dir.t line 50.
#     Structures begin differing at:
#          $got->[0] = '1'
#     $expected->[0] = '0'
#   Failed test at t/can_write_dir.t line 51.
#     Structures begin differing at:
#          $got->[0] = '1'
#     $expected->[0] = '0'
# Looks like you failed 2 tests of 12.
FAILED at test 7

Test snippet:

     45     ok chmod 0555, $exists, 'make read only';
     46
     47     skip "Current user or OS cannot create directories that they cannot read", 6
     48           if -w $exists; # these tests require a directory we cant read
     49
     50     is_deeply [can_write_dir($exists)], [0, $exists];
     51     is_deeply [can_write_dir($subdir)], [0, $exists, $subdir];

2. Packlist.t

cpan/ExtUtils-Install/t/Packlist ................................. 
#   Failed test 'write() should croak on open failure'
#   at t/Packlist.t line 92.
#                   ''
#     doesn't match '(?^:Can't open file)'
# Looks like you failed 1 test of 35.
FAILED at test 18

Test snippet:

     86         chmod 0444, 'eplist';
     87
     88         SKIP: {
     89             skip("cannot write readonly files", 1) if -w 'eplist';
     90
     91             eval { ExtUtils::Packlist::write({}, 'eplist') };
     92             like( $@, qr/Can't open file/, 'write() should croak on open failure' );
     93         }

The test must fail as there is no such thing as file-based ACLs in AFS; see https://docs.openafs.org/UserGuide/HDRWQ46.html
Instead ACLs are set on directories. As AFS is not that common, so below you'll find an example. Anyhow, ./Configure detects AFS and displays a notice "AFS may be running... I'll be extra cautious then..."

% systemctl status afs.mount
● afs.mount - /afs
     Loaded: loaded (/proc/self/mountinfo)
     Active: active (mounted) since Fri 2024-01-19 13:28:15 CET; 1 month 16 days ago
      Until: Fri 2024-01-19 13:28:15 CET; 1 month 16 days ago
      Where: /afs
       What: AFS

% mkdir demo
% cd demo

% fs listacl -path .
Access list for . is
Normal rights:
  username rlidwka
  system:administrators rlidwka
  system:anyuser l

% echo Hello World > a_file

% ls -ld a_file
-rw-r--r--. 1 username grp 12 Mar  6 02:34 a_file

% cat a_file
Hello World

% chmod 0000 a_file

% ls -ld a_file
----------. 1 username grp 12 Mar  6 02:34 a_file

% getfacl a_file
# file: a_file
# owner: username
# group: grp
user::---
group::---
other::---

% cat a_file
Hello World

% echo "Have a nice day" >> a_file

% cat a_file
Hello World
Have a nice day

I am not familiar with Perl tests, but anyhow propose these patches:

1. can_write_dir

diff -p old/cpan/ExtUtils-Install/t/can_write_dir.t new/cpan/ExtUtils-Install/t/can_write_dir.t
*** old/cpan/ExtUtils-Install/t/can_write_dir.t	2023-11-28 12:57:27.000000000 +0100
--- new/cpan/ExtUtils-Install/t/can_write_dir.t	2024-03-12 23:27:30.000000000 +0100
***************
*** 5,10 ****
--- 5,11 ----
  use strict;
  use ExtUtils::Install;
  use File::Spec;
+ use Config;
  { package FS;  our @ISA = qw(File::Spec); }

  # Alias it for easier access
*************** is_deeply [can_write_dir($abs_dne)],
*** 35,43 ****
--- 36,47 ----
            ];

  SKIP: {
+     my $Curdir = File::Spec→curdir;
      my $exists = FS->catdir(qw(exists));
      my $subdir = FS->catdir(qw(exists subdir));

+     skip "AFS", 8
+ 	if $Config{afs} eq "true" && ($Curdir eq '.' || $Curdir =~ /^\Q$Config{afsroot}/);

      ok mkdir $exists;
      END { rmdir $exists }
*************** SKIP: {

2. Packlist

diff -p cpan/ExtUtils-Install/t/Packlist.t new/cpan/ExtUtils-Install/t/Packlist.t
*** old/cpan/ExtUtils-Install/t/Packlist.t	2023-11-28 12:57:27.000000000 +0100
--- new/cpan/ExtUtils-Install/t/Packlist.t	2024-03-13 00:14:32.000000000 +0100
*************** ok( $file_is_ready, 'write() can write a
*** 80,93 ****
  local *IN;

  SKIP: {
  	skip('cannot write files, some tests difficult', 3) unless $file_is_ready;

  	# set this file to read-only
  	chmod 0444, 'eplist';

! 	SKIP: {
  	    skip("cannot write readonly files", 1) if -w 'eplist';
!
  	    eval { ExtUtils::Packlist::write({}, 'eplist') };
  	    like( $@, qr/Can't open file/, 'write() should croak on open failure' );
  	}
--- 80,94 ----
  local *IN;

  SKIP: {
+     require Config;
  	skip('cannot write files, some tests difficult', 3) unless $file_is_ready;

  	# set this file to read-only
  	chmod 0444, 'eplist';

!   SKIP: {
  	    skip("cannot write readonly files", 1) if -w 'eplist';
! 	    skip "AFS"		if $Config::Config{afs};
  	    eval { ExtUtils::Packlist::write({}, 'eplist') };
  	    like( $@, qr/Can't open file/, 'write() should croak on open failure' );
  	}