From 8c7ed718e27099ba2cdc32c959ff8199ae7d966a Mon Sep 17 00:00:00 2001
From: "H.Merijn Brand" <h.m.brand@xs4all.nl>
Date: Mon, 4 May 2020 13:59:56 +0200
Subject: [PATCH] Re-order $Config{libpth} in DynaLoader in 64bit env

In a 64bit environment, force 64bit locations *before* 32bit locations.
This will move /usr/lib64 in front of /usr/lib and /lib64 in front of
/lib.  This is important if a module uses $Config{libpth} to find a
library to load, like FFI::CheckLib does. If a library is installed in
both locations, it is likely to pick the wrong one if the order is not
showing the correct architecture first
As this clutch only looks at trailing 64, it will have no impact on
locations differing completely, as /usr/lib vs /usr/lib/i386-linux-gnu/
like on debian.

Also just include existing PATH elements and filter duplicates.
---
 ext/DynaLoader/DynaLoader_pm.PL | 66 ++++++++++++++++++++++++++++++++-
 pod/perldelta.pod               | 11 ++++++
 2 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/ext/DynaLoader/DynaLoader_pm.PL b/ext/DynaLoader/DynaLoader_pm.PL
index 002569f98c74..6c8ad3ca4d5d 100644
--- a/ext/DynaLoader/DynaLoader_pm.PL
+++ b/ext/DynaLoader/DynaLoader_pm.PL
@@ -88,7 +88,7 @@ package DynaLoader;
 # Tim.Bunce@ig.co.uk, August 1994
 
 BEGIN {
-    $VERSION = '1.50';
+    $VERSION = '1.51';
 }
 
 EOT
@@ -245,6 +245,70 @@ if ($ENV{PERL_BUILD_EXPAND_CONFIG_VARS} && $ENV{PERL_BUILD_EXPAND_ENV_VARS}) {
 EOT
 }
 
+# Filter out PATH elements that do not exist (anymore) and filter duplicates
+#  e.g. /usr/lib64/gcc/x86_64-suse-linux/7/include-fixed might refer to
+#       the compiler path when perl was built and the current installed
+#       copiler updated to version 8 or higher
+{   my %seen;
+    @dl_library_path = grep { -d && !$seen{$_}++} @dl_library_path;
+}
+
+# In a 64bit environment, force 64bit locations *before* 32bit locations.
+# This will move /usr/lib64 in front of /usr/lib and /lib64 in front of
+# /lib.  This is important if a module uses $Config{libpth} to find a
+# library to load, like FFI::CheckLib does. If a library is installed in
+# both locations, it is likely to pick the wrong one if the order is not
+# showing the correct architecture first
+# As this clutch only looks at trailing 64, it will have no impact on
+# locations differing completely, as /usr/lib vs /usr/lib/i386-linux-gnu/
+# like on debian.
+# Example:
+#  $Config{libpth} = join " " => qw(
+#   /usr/local/lib
+#   /usr/lib64/gcc/x86_64-suse-linux/7/include-fixed
+#   /usr/lib64/gcc/x86_64-suse-linux/7/../../../../x86_64-suse-linux/lib
+#   /usr/lib
+#   /pro/local/lib
+#   /lib/../lib64
+#   /usr/lib/../lib64
+#   /lib
+#   /lib64
+#   /usr/lib64
+#   /usr/local/lib64
+#   );
+if ($Config{ptrsize} == 8) {
+    my (@libpth, %p);
+    # Group all libs to the base of with or without trailing 64
+    # --> with above example @libpth becomes qw(
+    #   /usr/local/lib
+    #   /usr/lib64/gcc/x86_64-suse-linux/7/include-fixed
+    #   /usr/lib64/gcc/x86_64-suse-linux/7/../../../../x86_64-suse-linux/lib
+    #   /usr/lib
+    #   /pro/local/lib
+    #   /lib/../lib
+    #   /usr/lib/../lib
+    #   /lib
+    #   /lib
+    #   /usr/lib
+    #   /usr/local/lib
+    # and %p becomes (only first part shown)
+    # {   "/lib"           => [
+    #         "/lib",
+    #         "/lib64"
+    #         ],
+    #     "/lib/../lib"    => [
+    #         "/lib/../lib64"
+    #         ],
+    for (@dl_library_path) {
+	my $p = s/64$//r;
+	push @libpth   => $p;
+	push @{$p{$p}} => $_;
+    }
+    # Then join them back in the original (base) order (preserved in @libpth)
+    # where the trailing sorts after the non-trailing 64, hence reverse sort
+    @dl_library_path = map { reverse sort @{delete $p{$_} || []} } @libpth;
+}
+
 if ( $Config::Config{d_libname_unique} ) {
     printf OUT <<'EOT', length($Config::Config{dlext}) + 1;
 sub mod2fname {
diff --git a/pod/perldelta.pod b/pod/perldelta.pod
index b43aea457fc3..a2e46e7e637d 100644
--- a/pod/perldelta.pod
+++ b/pod/perldelta.pod
@@ -129,6 +129,17 @@ L<XXX> has been upgraded from version A.xx to B.yy.
 
 If there was something important to note about this change, include that here.
 
+=item *
+
+L<DynaLoader> has been upgraded from version 1.50 to 1.51.
+
+@DynaLoader::dl_library_path will now save only existing PATH elements where
+duplicates are filtered.
+
+If $Conf{ptrsize} == 8 (64bit builds), @dl_library_path will sort 64bit
+locations in front of 32bit locations. This will force-mode /lib64 in
+front of /lib and /usr/lib64 in front of /usr/lib.
+
 =back
 
 =head2 Removed Modules and Pragmata