Latest update.

util/perl/OpenSSL/fallback.pm

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+# Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
+#
+# Licensed under the Apache License 2.0 (the "License").  You may not use
+# this file except in compliance with the License.  You can obtain a copy
+# in the file LICENSE in the source distribution or at
+# https://www.openssl.org/source/license.html
+
+=head1 NAME
+
+OpenSSL::fallback - push directories to the end of @INC at compile time
+
+=cut
+
+package OpenSSL::fallback;
+
+use strict;
+use warnings;
+use Carp;
+
+our $VERSION = '0.01';
+
+=head1 SYNOPSIS
+
+    use OpenSSL::fallback LIST;
+
+=head1 DESCRIPTION
+
+This small simple module simplifies the addition of fallback directories
+in @INC at compile time.
+
+It is used to add extra directories at the end of perl's search path so
+that later "use" or "require" statements will find modules which are not
+located on perl's default search path.
+
+This is similar to L<lib>, except the paths are I<appended> to @INC rather
+than prepended, thus allowing the use of a newer module on perl's default
+search path if there is one.
+
+=head1 CAVEAT
+
+Just like with B<lib>, this only works with Unix filepaths.
+Just like with L<lib>, this doesn't mean that it only works on Unix, but that
+non-Unix users must first translate their file paths to Unix conventions.
+
+    # VMS users wanting to put [.my.stuff] into their @INC should write:
+    use fallback 'my/stuff';
+
+=head1 NOTES
+
+If you try to add a file to @INC as follows, you will be warned, and the file
+will be ignored:
+
+    use fallback 'file.txt';
+
+The sole exception is the file F<MODULES.txt>, which must contain a list of
+sub-directories relative to the location of that F<MODULES.txt> file.
+All these sub-directories will be appended to @INC.
+
+=cut
+
+# Forward declare
+sub glob;
+
+use constant DEBUG => 0;
+
+sub import {
+    shift;                      # Skip module name
+
+    foreach (@_) {
+        my $path = $_;
+
+        if ($path eq '') {
+            carp "Empty compile time value given to use fallback";
+            next;
+        }
+
+        print STDERR "DEBUG: $path\n" if DEBUG;
+
+        unless (-e $path
+                && ($path =~ m/(?:^|\/)MODULES.txt/ || -d $path)) {
+            croak "Parameter to use fallback must be a directory, not a file";
+            next;
+        }
+
+        my @dirs = ();
+        if (-f $path) {         # It's a MODULES.txt file
+            (my $dir = $path) =~ s|/[^/]*$||; # quick dirname
+            open my $fh, $path or die "Could not open $path: $!\n";
+            while (my $l = <$fh>) {
+                $l =~ s|\R$||;        # Better chomp
+                my $d = "$dir/$l";
+                croak "All lines in $path must be a directory, not a file: $l"
+                    unless -e $d && -d $d;
+                push @INC, $d;
+            }
+        } else {                # It's a directory
+            push @INC, $path;
+        }
+    }
+}
+
+=head1 SEE ALSO
+
+L<FindBin> - optional module which deals with paths relative to the source
+file.
+
+=head1 AUTHOR
+
+Richard Levitte, 2019
+
+=cut
+