summaryrefslogtreecommitdiffstats
path: root/Bugzilla/Install/Requirements.pm
blob: dfdeafb70a7b38ea46034d5a05ea10f218a1e68b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
# -*- Mode: perl; indent-tabs-mode: nil -*-
#
# The contents of this file are subject to the Mozilla Public
# License Version 1.1 (the "License"); you may not use this file
# except in compliance with the License. You may obtain a copy of
# the License at http://www.mozilla.org/MPL/
#
# Software distributed under the License is distributed on an "AS
# IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
# implied. See the License for the specific language governing
# rights and limitations under the License.
#
# The Original Code is the Bugzilla Bug Tracking System.
#
# Contributor(s): Max Kanat-Alexander <mkanat@bugzilla.org>
#                 Marc Schumann <wurblzap@gmail.com>

package Bugzilla::Install::Requirements;

# NOTE: This package MUST NOT "use" any Bugzilla modules other than
# Bugzilla::Constants, anywhere. We may "use" standard perl modules.
#
# Subroutines may "require" and "import" from modules, but they
# MUST NOT "use."

use strict;

use Bugzilla::Constants;
use Bugzilla::Install::Util qw(vers_cmp install_string 
                               extension_requirement_packages);
use List::Util qw(max);
use Safe;
use Term::ANSIColor;

use base qw(Exporter);
our @EXPORT = qw(
    REQUIRED_MODULES
    OPTIONAL_MODULES
    FEATURE_FILES

    check_requirements
    check_graphviz
    have_vers
    install_command
    map_files_to_features
);

# This is how many *'s are in the top of each "box" message printed
# by checksetup.pl.
use constant TABLE_WIDTH => 71;

# The below two constants are subroutines so that they can implement
# a hook. Other than that they are actually constants.

# "package" is the perl package we're checking for. "module" is the name
# of the actual module we load with "require" to see if the package is
# installed or not. "version" is the version we need, or 0 if we'll accept
# any version.
#
# "blacklist" is an arrayref of regular expressions that describe versions that
# are 'blacklisted'--that is, even if the version is high enough, Bugzilla
# will refuse to say that it's OK to run with that version.
sub REQUIRED_MODULES {
    my $perl_ver = sprintf('%vd', $^V);
    my @modules = (
    {
        package => 'CGI.pm',
        module  => 'CGI',
        # Perl 5.10 requires CGI 3.33 due to a taint issue when
        # uploading attachments, see bug 416382.
        # Require CGI 3.21 for -httponly support, see bug 368502.
        version => (vers_cmp($perl_ver, '5.10') > -1) ? '3.33' : '3.21',
        # CGI::Carp in 3.46 and 3.47 breaks Template Toolkit
        blacklist => ['^3\.46$', '^3\.47$'],
    },
    {
        package => 'Digest-SHA',
        module  => 'Digest::SHA',
        version => 0
    },
    {
        package => 'TimeDate',
        module  => 'Date::Format',
        version => '2.21'
    },
    # 0.28 fixed some important bugs in DateTime.
    {
        package => 'DateTime',
        module  => 'DateTime',
        version => '0.28'
    },
    # 0.79 is required to work on Windows Vista and Windows Server 2008.
    # As correctly detecting the flavor of Windows is not easy,
    # we require this version for all Windows installations.
    # 0.71 fixes a major bug affecting all platforms.
    {
        package => 'DateTime-TimeZone',
        module  => 'DateTime::TimeZone',
        version => ON_WINDOWS ? '0.79' : '0.71'
    },
    {
        package => 'DBI',
        module  => 'DBI',
        version => '1.41'
    },
    # 2.22 fixes various problems related to UTF8 strings in hash keys,
    # as well as line endings on Windows.
    {
        package => 'Template-Toolkit',
        module  => 'Template',
        version => '2.22'
    },
    {
        package => 'Email-Send',
        module  => 'Email::Send',
        version => ON_WINDOWS ? '2.16' : '2.00',
        blacklist => ['^2\.196$']
    },
    {
        package => 'Email-MIME',
        module  => 'Email::MIME',
        version => '1.861'
    },
    {
        package => 'Email-MIME-Encodings',
        module  => 'Email::MIME::Encodings',
        # Fixes bug 486206
        version => '1.313',
    },
    {
        package => 'Email-MIME-Modifier',
        module  => 'Email::MIME::Modifier',
        version => '1.442'
    },
    {
        package => 'URI',
        module  => 'URI',
        version => 0
    },
    );

    my $extra_modules = _get_extension_requirements('REQUIRED_MODULES');
    push(@modules, @$extra_modules);
    return \@modules;
};

sub OPTIONAL_MODULES {
    my @modules = (
    {
        package => 'GD',
        module  => 'GD',
        version => '1.20',
        feature => [qw(graphical_reports new_charts old_charts)],
    },
    {
        package => 'Chart',
        module  => 'Chart::Lines',
        # Versions below 2.1 cannot be detected accurately.
        version => '2.1',
        feature => [qw(new_charts old_charts)],
    },
    {
        package => 'Template-GD',
        # This module tells us whether or not Template-GD is installed
        # on Template-Toolkits after 2.14, and still works with 2.14 and lower.
        module  => 'Template::Plugin::GD::Image',
        version => 0,
        feature => ['graphical_reports'],
    },
    {
        package => 'GDTextUtil',
        module  => 'GD::Text',
        version => 0,
        feature => ['graphical_reports'],
    },
    {
        package => 'GDGraph',
        module  => 'GD::Graph',
        version => 0,
        feature => ['graphical_reports'],
    },
    {
        package => 'XML-Twig',
        module  => 'XML::Twig',
        version => 0,
        feature => ['moving', 'updates'],
    },
    {
        package => 'MIME-tools',
        # MIME::Parser is packaged as MIME::Tools on ActiveState Perl
        module  => ON_WINDOWS ? 'MIME::Tools' : 'MIME::Parser',
        version => '5.406',
        feature => ['moving'],
    },
    {
        package => 'libwww-perl',
        module  => 'LWP::UserAgent',
        version => 0,
        feature => ['updates'],
    },
    {
        package => 'PatchReader',
        module  => 'PatchReader',
        version => '0.9.4',
        feature => ['patch_viewer'],
    },
    {
        package => 'perl-ldap',
        module  => 'Net::LDAP',
        version => 0,
        feature => ['auth_ldap'],
    },
    {
        package => 'Authen-SASL',
        module  => 'Authen::SASL',
        version => 0,
        feature => ['smtp_auth'],
    },
    {
        package => 'RadiusPerl',
        module  => 'Authen::Radius',
        version => 0,
        feature => ['auth_radius'],
    },
    {
        package => 'SOAP-Lite',
        module  => 'SOAP::Lite',
        # 0.710.04 is required for correct UTF-8 handling, but .04 and .05 are
        # affected by bug 468009.
        version => '0.710.06',
        feature => ['xmlrpc'],
    },
    {
        package => 'JSON-RPC',
        module  => 'JSON::RPC',
        version => 0,
        feature => ['jsonrpc'],
    },
    {
        package => 'Test-Taint',
        module  => 'Test::Taint',
        version => 0,
        feature => ['jsonrpc', 'xmlrpc'],
    },
    {
        # We need the 'utf8_mode' method of HTML::Parser, for HTML::Scrubber.
        package => 'HTML-Parser',
        module  => 'HTML::Parser',
        version => '3.40',
        feature => ['html_desc'],
    },
    {
        package => 'HTML-Scrubber',
        module  => 'HTML::Scrubber',
        version => 0,
        feature => ['html_desc'],
    },

    # Inbound Email
    {
        package => 'Email-MIME-Attachment-Stripper',
        module  => 'Email::MIME::Attachment::Stripper',
        version => 0,
        feature => ['inbound_email'],
    },
    {
        package => 'Email-Reply',
        module  => 'Email::Reply',
        version => 0,
        feature => ['inbound_email'],
    },

    # Mail Queueing
    {
        package => 'TheSchwartz',
        module  => 'TheSchwartz',
        version => 0,
        feature => ['jobqueue'],
    },
    {
        package => 'Daemon-Generic',
        module  => 'Daemon::Generic',
        version => 0,
        feature => ['jobqueue'],
    },

    # mod_perl
    {
        package => 'mod_perl',
        module  => 'mod_perl2',
        version => '1.999022',
        feature => ['mod_perl'],
    },
    );

    my $extra_modules = _get_extension_requirements('OPTIONAL_MODULES');
    push(@modules, @$extra_modules);
    return \@modules;
};

# This maps features to the files that require that feature in order
# to compile. It is used by t/001compile.t and mod_perl.pl.
use constant FEATURE_FILES => (
    jsonrpc       => ['Bugzilla/WebService/Server/JSONRPC.pm', 'jsonrpc.cgi'],
    xmlrpc        => ['Bugzilla/WebService/Server/XMLRPC.pm', 'xmlrpc.cgi',
                      'Bugzilla/WebService.pm', 'Bugzilla/WebService/*.pm'],
    moving        => ['importxml.pl'],
    auth_ldap     => ['Bugzilla/Auth/Verify/LDAP.pm'],
    auth_radius   => ['Bugzilla/Auth/Verify/RADIUS.pm'],
    inbound_email => ['email_in.pl'],
    jobqueue      => ['Bugzilla/Job/*', 'Bugzilla/JobQueue.pm',
                      'Bugzilla/JobQueue/*', 'jobqueue.pl'],
    patch_viewer  => ['Bugzilla/Attachment/PatchReader.pm'],
    updates       => ['Bugzilla/Update.pm'],
);

# This implements the REQUIRED_MODULES and OPTIONAL_MODULES stuff
# described in in Bugzilla::Extension.
sub _get_extension_requirements {
    my ($function) = @_;

    my $packages = extension_requirement_packages();
    my @modules;
    foreach my $package (@$packages) {
        if ($package->can($function)) {
            my $extra_modules = $package->$function;
            push(@modules, @$extra_modules);
        }
    }
    return \@modules;
};

sub check_requirements {
    my ($output) = @_;

    print "\n", install_string('checking_modules'), "\n" if $output;
    my $root = ROOT_USER;
    my $missing = _check_missing(REQUIRED_MODULES, $output);

    print "\n", install_string('checking_dbd'), "\n" if $output;
    my $have_one_dbd = 0;
    my $db_modules = DB_MODULE;
    foreach my $db (keys %$db_modules) {
        my $dbd = $db_modules->{$db}->{dbd};
        $have_one_dbd = 1 if have_vers($dbd, $output);
    }

    print "\n", install_string('checking_optional'), "\n" if $output;
    my $missing_optional = _check_missing(OPTIONAL_MODULES, $output);

    # If we're running on Windows, reset the input line terminator so that
    # console input works properly - loading CGI tends to mess it up
    $/ = "\015\012" if ON_WINDOWS;

    my $pass = !scalar(@$missing) && $have_one_dbd;
    return {
        pass     => $pass,
        one_dbd  => $have_one_dbd,
        missing  => $missing,
        optional => $missing_optional,
        any_missing => !$pass || scalar(@$missing_optional),
    };
}

# A helper for check_requirements
sub _check_missing {
    my ($modules, $output) = @_;

    my @missing;
    foreach my $module (@$modules) {
        unless (have_vers($module, $output)) {
            push(@missing, $module);
        }
    }

    return \@missing;
}

# Returns the build ID of ActivePerl. If several versions of
# ActivePerl are installed, it won't be able to know which one
# you are currently running. But that's our best guess.
sub _get_activestate_build_id {
    eval 'use Win32::TieRegistry';
    return 0 if $@;
    my $key = Win32::TieRegistry->new('LMachine\Software\ActiveState\ActivePerl')
      or return 0;
    return $key->GetValue("CurrentVersion");
}

sub print_module_instructions {
    my ($check_results, $output) = @_;

    # First we print the long explanatory messages.

    if (scalar @{$check_results->{missing}}) {
        print install_string('modules_message_required');
    }

    if (!$check_results->{one_dbd}) {
        print install_string('modules_message_db');
    }

    if (my @missing = @{$check_results->{optional}} and $output) {
        print install_string('modules_message_optional');
        # Now we have to determine how large the table cols will be.
        my $longest_name = max(map(length($_->{package}), @missing));

        # The first column header is at least 11 characters long.
        $longest_name = 11 if $longest_name < 11;

        # The table is TABLE_WIDTH characters long. There are seven mandatory
        # characters (* and space) in the string. So, we have a total
        # of TABLE_WIDTH - 7 characters to work with.
        my $remaining_space = (TABLE_WIDTH - 7) - $longest_name;
        print '*' x TABLE_WIDTH . "\n";
        printf "* \%${longest_name}s * %-${remaining_space}s *\n",
               'MODULE NAME', 'ENABLES FEATURE(S)';
        print '*' x TABLE_WIDTH . "\n";
        foreach my $package (@missing) {
            printf "* \%${longest_name}s * %-${remaining_space}s *\n",
                   $package->{package}, 
                   _translate_feature($package->{feature});
        }
    }

    # We only print the PPM repository note if we have to.
    if ((!$output && @{$check_results->{missing}})
        || ($output && $check_results->{any_missing}))
    {
        if (ON_WINDOWS) {
            my $perl_ver = sprintf('%vd', $^V);
            
            # URL when running Perl 5.8.x.
            my $url_to_theory58S = 'http://theoryx5.uwinnipeg.ca/ppms';
            # Packages for Perl 5.10 are not compatible with Perl 5.8.
            if (vers_cmp($perl_ver, '5.10') > -1) {
                $url_to_theory58S = 'http://cpan.uwinnipeg.ca/PPMPackages/10xx/';
            }
            print colored(install_string('ppm_repo_add', 
                                 { theory_url => $url_to_theory58S }), 'red');
            # ActivePerls older than revision 819 require an additional command.
            if (_get_activestate_build_id() < 819) {
                print install_string('ppm_repo_up');
            }
        }

        # If any output was required, we want to close the "table"
        print "*" x TABLE_WIDTH . "\n";
    }

    # And now we print the actual installation commands.

    if (my @missing = @{$check_results->{optional}} and $output) {
        print install_string('commands_optional') . "\n\n";
        foreach my $module (@missing) {
            my $command = install_command($module);
            printf "%15s: $command\n", $module->{package};
        }
        print "\n";
    }

    if (!$check_results->{one_dbd}) {
        print install_string('commands_dbd') . "\n";
        my %db_modules = %{DB_MODULE()};
        foreach my $db (keys %db_modules) {
            my $command = install_command($db_modules{$db}->{dbd});
            printf "%10s: \%s\n", $db_modules{$db}->{name}, $command;
        }
        print "\n";
    }

    if (my @missing = @{$check_results->{missing}}) {
        print colored(install_string('commands_required'), 'red') . "\n";
        foreach my $package (@missing) {
            my $command = install_command($package);
            print "    $command\n";
        }
    }

    if ($output && $check_results->{any_missing} && !ON_WINDOWS
        && !$check_results->{hide_all}) 
    {
        print install_string('install_all', { perl => $^X });
    }
    if (!$check_results->{pass}) {
        print colored(install_string('installation_failed'), 'red') . "\n\n";
    }
}

sub _translate_feature {
    my $features = shift;
    my @strings;
    foreach my $feature (@$features) {
        push(@strings, install_string("feature_$feature"));
    }
    return join(', ', @strings);
}

sub check_graphviz {
    my ($output) = @_;

    return 1 if (Bugzilla->params->{'webdotbase'} =~ /^https?:/);

    printf("Checking for %15s %-9s ", "GraphViz", "(any)") if $output;

    my $return = 0;
    if(-x Bugzilla->params->{'webdotbase'}) {
        print "ok: found\n" if $output;
        $return = 1;
    } else {
        print "not a valid executable: " . Bugzilla->params->{'webdotbase'} . "\n";
    }

    my $webdotdir = bz_locations()->{'webdotdir'};
    # Check .htaccess allows access to generated images
    if (-e "$webdotdir/.htaccess") {
        my $htaccess = new IO::File("$webdotdir/.htaccess", 'r') 
            || die "$webdotdir/.htaccess: " . $!;
        if (!grep(/png/, $htaccess->getlines)) {
            print "Dependency graph images are not accessible.\n";
            print "delete $webdotdir/.htaccess and re-run checksetup.pl to fix.\n";
        }
        $htaccess->close;
    }

    return $return;
}

# This was originally clipped from the libnet Makefile.PL, adapted here to
# use the below vers_cmp routine for accurate version checking.
sub have_vers {
    my ($params, $output) = @_;
    my $module  = $params->{module};
    my $package = $params->{package};
    if (!$package) {
        $package = $module;
        $package =~ s/::/-/g;
    }
    my $wanted  = $params->{version};

    eval "require $module;";

    # VERSION is provided by UNIVERSAL::
    my $vnum = eval { $module->VERSION } || -1;

    # CGI's versioning scheme went 2.75, 2.751, 2.752, 2.753, 2.76
    # That breaks the standard version tests, so we need to manually correct
    # the version
    if ($module eq 'CGI' && $vnum =~ /(2\.7\d)(\d+)/) {
        $vnum = $1 . "." . $2;
    }

    my $vstr;
    if ($vnum eq "-1") { # string compare just in case it's non-numeric
        $vstr = install_string('module_not_found');
    }
    elsif (vers_cmp($vnum,"0") > -1) {
        $vstr = install_string('module_found', { ver => $vnum });
    }
    else {
        $vstr = install_string('module_unknown_version');
    }

    my $vok = (vers_cmp($vnum,$wanted) > -1);
    my $blacklisted;
    if ($vok && $params->{blacklist}) {
        $blacklisted = grep($vnum =~ /$_/, @{$params->{blacklist}});
        $vok = 0 if $blacklisted;
    }

    if ($output) {
        my $ok           = $vok ? install_string('module_ok') : '';
        my $black_string = $blacklisted ? install_string('blacklisted') : '';
        my $want_string  = $wanted ? "v$wanted" : install_string('any');

        $ok = "$ok:" if $ok;
        my $str = sprintf "%s %19s %-9s $ok $vstr $black_string\n",
                    install_string('checking_for'), $package, "($want_string)";
        print $vok ? $str : colored($str, 'red');
    }
    
    return $vok ? 1 : 0;
}

sub install_command {
    my $module = shift;
    my ($command, $package);

    if (ON_WINDOWS) {
        $command = 'ppm install %s';
        $package = $module->{package};
    }
    else {
        $command = "$^X install-module.pl \%s";
        # Non-Windows installations need to use module names, because
        # CPAN doesn't understand package names.
        $package = $module->{module};
    }
    return sprintf $command, $package;
}

# This does a reverse mapping for FEATURE_FILES.
sub map_files_to_features {
    my %features = FEATURE_FILES;
    my %files;
    foreach my $feature (keys %features) {
        my @my_files = @{ $features{$feature} };
        foreach my $pattern (@my_files) {
            foreach my $file (glob $pattern) {
                $files{$file} = $feature;
            }
        }
    }
    return \%files;
}

1;

__END__

=head1 NAME

Bugzilla::Install::Requirements - Functions and variables dealing
  with Bugzilla's perl-module requirements.

=head1 DESCRIPTION

This module is used primarily by C<checksetup.pl> to determine whether
or not all of Bugzilla's prerequisites are installed. (That is, all the
perl modules it requires.)

=head1 CONSTANTS

=over

=item C<REQUIRED_MODULES>

An arrayref of hashrefs that describes the perl modules required by 
Bugzilla. The hashes have three keys: 

=over

=item C<package> - The name of the Perl package that you'd find on
CPAN for this requirement. 

=item C<module> - The name of a module that can be passed to the
C<install> command in C<CPAN.pm> to install this module.

=item C<version> - The version of this module that we require, or C<0>
if any version is acceptable.

=back

=item C<OPTIONAL_MODULES>

An arrayref of hashrefs that describes the perl modules that add
additional features to Bugzilla if installed. Its hashes have all
the fields of L</REQUIRED_MODULES>, plus a C<feature> item--an arrayref
of strings that describe what features require this module.

=item C<FEATURE_FILES>

A hashref that describes what files should only be compiled if a certain
feature is enabled. The feature is the key, and the values are arrayrefs
of file names (which are passed to C<glob>, so shell patterns work).

=back


=head1 SUBROUTINES

=over 4

=item C<check_requirements>

=over

=item B<Description>

This checks what optional or required perl modules are installed, like
C<checksetup.pl> does.

=item B<Params>

=over

=item C<$output> - C<true> if you want the function to print out information
about what it's doing, and the versions of everything installed.

=back

=item B<Returns>

A hashref containing these values:

=over

=item C<pass> - Whether or not we have all the mandatory requirements.

=item C<missing> - An arrayref containing any required modules that
are not installed or that are not up-to-date. Each item in the array is
a hashref in the format of items from L</REQUIRED_MODULES>.

=item C<optional> - The same as C<missing>, but for optional modules.

=item C<have_one_dbd> - True if at least one C<DBD::> module is installed.

=item C<any_missing> - True if there are any missing modules, even optional
modules.

=back

=back

=item C<check_graphviz($output)>

Description: Checks if the graphviz binary specified in the 
  C<webdotbase> parameter is a valid binary, or a valid URL.

Params:      C<$output> - C<$true> if you want the function to
                 print out information about what it's doing.

Returns:     C<1> if the check was successful, C<0> otherwise.

=item C<have_vers($module, $output)>

 Description: Tells you whether or not you have the appropriate
              version of the module requested. It also prints
              out a message to the user explaining the check
              and the result.

 Params:      C<$module> - A hashref, in the format of an item from 
                           L</REQUIRED_MODULES>.
              C<$output> - Set to true if you want this function to
                           print information to STDOUT about what it's
                           doing.

 Returns:   C<1> if you have the module installed and you have the
            appropriate version. C<0> otherwise.

=item C<install_command($module)>

 Description: Prints out the appropriate command to install the
              module specified, depending on whether you're
              on Windows or Linux.

 Params:      C<$module> - A hashref, in the format of an item from
                           L</REQUIRED_MODULES>.

 Returns:     nothing

=item C<map_files_to_features>

Returns a hashref where file names are the keys and the value is the feature
that must be enabled in order to compile that file.

=back