This file is indexed.

/usr/share/perl5/Config/Std.pm is in libconfig-std-perl 0.901-2.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

   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
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
package Config::Std;

our $VERSION = '0.901';

require v5.7.3; # RT#21184

my %global_def_sep;
my %global_inter_gap;

sub import {
    my ($package, $opt_ref) = @_;
    my $caller = caller();
    $global_def_sep{$caller} = $opt_ref->{def_sep};
    $global_inter_gap{$caller} = $opt_ref->{def_gap};
    for my $sub_name (qw( read_config write_config )) {
        $opt_ref->{$sub_name} ||= $sub_name;
    }
    *{$caller.'::'.$opt_ref->{read_config}}  = \&Config::Std::Hash::read_config;
    *{$caller.'::'.$opt_ref->{write_config}} = \&Config::Std::Hash::write_config;
}

package Config::Std::Gap;
use Class::Std;
{
    sub serialize { return "\n" }
    sub update  {}
    sub extend  {}
    sub copy_to {}
}

package Config::Std::Comment;
use Class::Std;
{
    my %text_of : ATTR( :init_arg<text> );

    sub serialize {
        my ($self) = @_;
        return $text_of{ident $self};
    }

    sub append_comment {
        my ($self, $new_text) = @_;
        $text_of{ident $self} .= $new_text;
    }

    sub update  {}
    sub extend  {}
    sub copy_to {}
}

package Config::Std::Keyval;
use Class::Std;
{
    my %key_of      : ATTR( :init_arg<key> :get<key> );
    my %vals_of     : ATTR;
    my %deleted_of  : ATTR;

    sub BUILD {
        my ($self, $ident, $arg_ref) = @_;

        $vals_of{$ident}     = [ { %{$arg_ref} } ];
    }

    my %SEPARATOR = ( ':' => ': ', '=' => ' = ' );

    use Carp;

    sub serialize {
        my ($self, $def_sep, $block_name) = @_;
        my $ident = ident $self;

        return "" if $deleted_of{$ident};

        my ($key, $vals) = ($key_of{$ident}, $vals_of{$ident});

        my $keyspace = q{ } x length($key);

        my $serialization = q{};

        for $n (0..$#{$vals}) {
            my ($val,$sep,$comm) = @{$vals->[$n]}{qw(val sep comm)};

            my $val_type = ref $val;
            croak qq{Can't save \L$val_type\E ref as value for key {'$block_name'}{'$key'} (only scalars or array refs)}
                if $val_type && $val_type ne 'ARRAY';

            $sep = $SEPARATOR{$sep || $def_sep};

            my @vals = $val_type eq 'ARRAY' ? @{$val} : $val;
            s/ (?!\Z) \n /\n$keyspace$sep/gxms for @vals;

            $serialization .= $comm || q{};

            $serialization .= join q{}, map {"$key$sep$_\n"} @vals;
        }

        return $serialization;
    }

    sub update { 
        my ($self, $hash_ref, $updated_ref) = @_;
        my $ident = ident $self;

        my $key = $key_of{$ident};

        if (!exists $hash_ref->{$key}) {
            $deleted_of{$ident} = 1;
        }
        else {
            my $val = $hash_ref->{$key};
            @newvals = ref $val eq 'ARRAY' ? @{$val} : $val;
            for my $n (0..$#newvals) {
                $vals_of{$ident}[$n]{val} = $newvals[$n];
            }
            splice @{$vals_of{$ident}}, scalar @newvals;
        }

        $updated_ref->{$key} = 1;

        return 1;
    }

    sub copy_to {
        my ($self, $hash_ref)  = @_;
        my $ident = ident $self;
        my @vals = map $_->{val}, @{$vals_of{$ident}};
        $hash_ref->{$key_of{$ident}} = @vals > 1 ? \@vals : $vals[0];
    }

    sub multivalue {
        my ($self, $sep, $val, $comm) = @_;
        push @{$vals_of{ident $self}}, {val=>$val, sep=>$sep, comm=>$comm};
    }
}

package Config::Std::Block;
use Class::Std;
{
    my %name_of         : ATTR( :init_arg<name> :get<name> default => '' );
    my %sep_count_of    : ATTR;
    my %precomm_of      : ATTR( :init_arg<precomm> default => '' );
    my %parcomm_of      : ATTR( :init_arg<parcomm> default => '' );
    my %components_of   : ATTR;
    my %deleted_of      : ATTR;
    my %seen            : ATTR;
    my %is_first        : ATTR( :init_arg<first> default => '' );

    sub BUILD {
        my ($self, $ident) = @_;
        @{$sep_count_of{$ident}}{':','='} = (0,0);
        $components_of{$ident} = [];
        $seen{$ident} = {};
    }

    sub copy_to {
        my ($self, $hash_ref) = @_;
        my $ident = ident $self;

        my $keyvals = $hash_ref->{$name_of{$ident}} ||= {};

        for my $comp ( @{$components_of{$ident}} ) {
            $comp->copy_to($keyvals);
        }

        $hash_ref->{$name_of{$ident}} = $keyvals;
    }

    sub serialize {
        my ($self, $first, $caller, $post_gap, $inter_gap) = @_;
        my $ident = ident $self;

        return q{} if $deleted_of{$ident};

        my $is_anon = $first && length($name_of{$ident}) == 0;

        my $serialization = q{};
        if (!$is_anon) {
            $serialization = ($precomm_of{$ident} || q{})
                           . "[$name_of{$ident}]"
                           . (defined $parcomm_of{$ident}?$parcomm_of{$ident}:q{})
                           . "\n";
        }

        my $gds = $global_def_sep{$caller};
        my $def_sep
            = defined $gds                                             ? $gds
            : $sep_count_of{$ident}{':'} >= $sep_count_of{$ident}{'='} ? ':'
            :                                                            '='
            ;

        $self->ensure_gap() if $inter_gap && !$is_anon;

        for my $comp ( @{$components_of{$ident}} ) {
            $serialization .= $comp->serialize($def_sep, $name_of{$ident});
        }

        return $serialization;
    }

    sub update {
        my ($self, $hash_ref, $updated_ref) = @_;
        my $ident = ident $self;

        if (!defined $hash_ref) {
            $deleted_of{$ident} = 1;
            return;
        }

        for my $comp ( @{$components_of{$ident}} ) {
            $comp->update($hash_ref, $updated_ref) or next;
        }
    }

    sub extend {
        my ($self, $hash_ref, $updated_ref, $post_gap, $inter_gap) = @_;

        # Only the first occurrence of a block has new keys added...
        return unless $is_first{ident $self};

        my $first = 1;
	# RT 85956 
        for my $key ( sort grep {!$updated_ref->{$_}} keys %{$hash_ref}) {
            my $value = $hash_ref->{$key};
            my $separate = ref $value || $value =~ m/\n./xms;
            $self->ensure_gap() if ($first ? $post_gap : $inter_gap)
                                    || $separate;
            $self->add_keyval($key, undef, $hash_ref->{$key});
            $self->add_gap() if $separate;
            $first = 0;
        }
    }

    sub ensure_gap {
        my ($self) = @_;
        my $comp_ref = $components_of{ident $self};
        return if @{$comp_ref} && $comp_ref->[-1]->isa('Config::Std::Gap');
        push @{$comp_ref}, Config::Std::Gap->new();
    }

    sub add_gap {
        my ($self) = @_;
        push @{$components_of{ident $self}}, Config::Std::Gap->new();
    }

    sub add_comment {
        my ($self, $text) = @_;
        my $comp_ref = $components_of{ident $self};
        if ($comp_ref && @{$comp_ref} && $comp_ref->[-1]->isa('Config::Std::Comment') ) {
            $comp_ref->[-1]->append_comment($text);
        }
        else {
            push @{$comp_ref}, Config::Std::Comment->new({text=>$text});
        }
    }

    sub add_keyval {
        my ($self, $key, $sep, $val, $comm) = @_;
        my $ident = ident $self;

        $sep_count_of{$ident}{$sep}++ if $sep;

        my $seen = $seen{$ident};

        if ($seen->{$key}) {
            $seen->{$key}->multivalue($sep, $val, $comm);
            return;
        }

        my $keyval 
            = Config::Std::Keyval->new({key=>$key, sep=>$sep, val=>$val, comm=>$comm});
        push @{$components_of{$ident}}, $keyval;
        $seen->{$key} = $keyval;
    }
}

package Config::Std::Hash;
use Class::Std;
{

    use Carp;
    use Fcntl ':flock';     # import LOCK_* constants

    my %post_section_gap_for :ATTR;
    my %array_rep_for        :ATTR;
    my %filename_for         :ATTR;

    sub write_config (\[%$];$) {
        my ($hash_ref, $filename) = @_;
        $hash_ref = ${$hash_ref} if ref $hash_ref eq 'REF';

        $filename = $filename_for{$hash_ref} if @_<2;

        croak "Missing filename for call to write_config()"
            unless $filename;

        my $caller = caller;

        my $inter_gap
            = exists $global_inter_gap{$caller} ? $global_inter_gap{$caller}
            :                                      1;
        my $post_gap
            = $post_section_gap_for{$hash_ref}
            || (defined $global_inter_gap{$caller} ? $global_inter_gap{$caller}
                                                   : 1
               );

        # Update existing keyvals in each block...
        my %updated;
        for my $block ( @{$array_rep_for{$hash_ref}} ) {
            my $block_name = $block->get_name();
            $block->update($hash_ref->{$block_name}, $updated{$block_name}||={});
        }

        # Add new keyvals to the first section of block...
        for my $block ( @{$array_rep_for{$hash_ref}} ) {
            my $block_name = $block->get_name();
            $block->extend($hash_ref->{$block_name}, $updated{$block_name},
                           $post_gap, inter_gap
                          );
        }

        # Add new blocks at the end...
        for my $block_name ( sort grep {!$updated{$_}} keys %{$hash_ref} ) {
            my $block = Config::Std::Block->new({name=>$block_name});
            my $subhash = $hash_ref->{$block_name};
            my $first = 1;
	    # RT 85956
            for my $key ( sort keys %{$subhash} ) {
                if (!defined $subhash->{$key}) {
                    croak "Can't save undefined value for key {'$block_name'}{'$key'} (only scalars or array refs)";
                }
                my $value = $subhash->{$key};
                my $separate = ref $value || $value =~ m/\n./xms;
                $block->ensure_gap() if ($first ? $post_gap : $inter_gap)
                                     || $separate;
                $block->add_keyval($key, undef, $value);
                $block->add_gap() if $separate;
                $first = 0;
            }
            $block->ensure_gap();
            push @{$array_rep_for{$hash_ref}}, $block;
        }

        open my $fh, '>', $filename
            or croak "Can't open config file '$filename' for writing (\L$!\E)";

        flock($fh,LOCK_EX|LOCK_NB)
            || croak "Can't write to locked config file '$filename'"
                if ! ref $filename;

        my $first = 1;
        for my $block ( @{$array_rep_for{$hash_ref}} ) {
            print {$fh} $block->serialize($first, scalar caller, $post_gap);
            $first = 0;
        }

        flock($fh,LOCK_UN) if ! ref $filename;

        return 1;
    }

    sub read_config ($\[%$]) {
        my ($filename, $var_ref, $opt_ref) = @_;
        my $var_type = ref($var_ref) || q{};
        my $hash_ref;
        if ($var_type eq 'SCALAR' && !defined ${$var_ref} ) {
            ${$var_ref} = $hash_ref = {};
        }
        elsif ($var_type eq 'HASH') {
            $hash_ref = $var_ref;
        }
        else {
            croak q{Scalar second argument to 'read_config' must be empty};
        }

        bless $hash_ref, 'Config::Std::Hash';

        my $blocks = $array_rep_for{$hash_ref}
                   = _load_config_for($filename, $hash_ref);

        for my $block ( @{$blocks} ) {
            $block->copy_to($hash_ref);
        }

        $filename_for{$hash_ref} = $filename;

        # Remove initial empty section if no data...
        if (!keys %{ $hash_ref->{q{}} }) {
            delete $hash_ref->{q{}};
        }

        return 1;
    }

    sub _load_config_for {
        my ($filename, $hash_ref) = @_;

        open my $fh, '<', $filename
            or croak "Can't open config file '$filename' (\L$!\E)";
        flock($fh,LOCK_SH|LOCK_NB)
            || croak "Can't read from locked config file '$filename'"
                if !ref $filename;
        my $text = do{local $/; <$fh>};
        flock($fh,LOCK_UN) if !ref $filename;

        my @config_file = Config::Std::Block->new({ name=>q{}, first=>1 });
        my $comment = q{};
        my %seen;

        # Start tracking whether section markers have gaps after them...
        $post_section_gap_for{$hash_ref} = 0;

        for ($text) {
            pos = 0;
            while (pos() < length() ) {
                # Gap...
                if (m/\G (?: [^\S\n]* (?:\n|\z)+)/gcxms) {
                    ### Found gap
                    $config_file[-1]->add_comment($comment) if $comment;
                    $config_file[-1]->add_gap();
                    $comment = q{};
                }

                # Comment...
                elsif (m/\G (\s* [#;] [^\n]* (?:\n|\z) )/gcxms) {
                    ### Found comment: $1
                    $comment .= $1;
                }

                # Block...
                elsif (m/\G ([^\S\n]*) [[]  ( [^]\n]* ) []] ( ([^\S\n]*) [#;] [^\n]* )? [^\S\n]* (?:\n|\z)/gcxms) {
                    my ($pre, $name, $parcomm, $ws) = ($1, $2, $3, $4);
                    ### Found block: $name
                    if ($parcomm) {
                        $pre = 2 + length($pre) + length($name) + length($ws);
                        if (m/\G ( (?: \n? [ ]{$pre,} [#] [^\n]* )+ )/gcxms) {
                            $parcomm .= "\n$1";
                        }
                    }
                    push @config_file,
                            Config::Std::Block->new({
                                name    => $name,
                                precomm => $comment,
                                parcomm => $parcomm,
                                first   => !$seen{$name}++,
                            });
                    $comment = q{};

                    # Check for trailing gap...
                    $post_section_gap_for{$hash_ref}
                        += m/\G (?= [^\S\n]* (?:\n|\z) )/xms ? +1 : -1;
                }

                # Key/value...
                elsif (m/\G [^\S\n]* ([^=:\n]+?) [^\S\n]* ([:=] [^\S\n]*) ([^\n]*) (?:\n|\z)/gcxms) {
                    my ($key, $sep, $val) = ($1, $2, $3);

                    my $pure_sep = $sep;
                    $pure_sep =~ s/\s*//g;

                    # Continuation lines...
                    my $continued = 0;
                    while (m/\G [^\S\n]* \Q$sep\E ([^\n]*) (?:\n|\z) /gcxms
                       ||  m/\G [^\S\n]* \Q$pure_sep\E ([^\n]*) (?:\n|\z) /gcxms
                    ) {
                        $val .= "\n$1";
                        $continued = 1;
                    }

                    $val =~ s/\A \s*|\s* \z//gxms if !$continued;

                    ### Found kv: $key, $val

                    $config_file[-1]->add_keyval($key, $pure_sep, $val,
                    $comment); $comment = q{}; }

                # Mystery...
                else {
                    my ($problem) = m/\G ([^\n]{10,40}|.{10}) /gcxms;
                    die "Error in config file '$filename' near:\n\n\t$problem\n";
                }
            }
        }

        return \@config_file;
    }

}


1; # Magic true value required at end of module
__END__

=head1 NAME

Config::Std - Load and save configuration files in a standard format


=head1 VERSION

This document describes Config::Std version 0.901


=head1 SYNOPSIS

    use Config::Std;

    # Load named config file into specified hash...
    read_config 'demo2.cfg' => my %config;

    # Extract the value of a key/value pair from a specified section...
    $config_value = $config{Section_label}{key};

    # Change (or create) the value of a key/value pair...
    $config{Other_section_label}{other_key} = $new_val;

    # Update the config file from which this hash was loaded...
    write_config %config;

    # Write the config information to another file as well...
    write_config %config, $other_file_name;

  
=head1 DESCRIPTION

This module implements yet another damn configuration-file system.

The configuration language is deliberately simple and limited, and the
module works hard to preserve as much information (section order,
comments, etc.) as possible when a configuration file is updated.

The whole point of Config::Std is to encourage use of one standard layout
and syntax in config files. Damian says "I could have gotten away with it, I would have
only allowed one separator. But it proved impossible to choose between C<:> and C<=>
(half the people I asked wanted one, half wanted the other)." 
Providing round-trip file re-write is the spoonful of sugar to help the medicine go down.
The supported syntax is within the general INI file family 

See Chapter 19 of "Perl Best Practices" (O'Reilly, 2005) 
for more detail on the
rationale for this approach. 

=head2 Configuration language

The configuration language is a slight extension of the Windows INI format.

=head3 Comments

A comment starts with a C<#> character (Perl-style) or a C<;> character
(INI-style), and runs to the end of the same line:

    # This is a comment

    ; Ywis, eke hight thilke

Comments can be placed almost anywhere in a configuration file, except inside
a section label, or in the key or value of a configuration variable:

    # Valid comment
    [ # Not a comment, just a weird section label ]

    ; Valid comment
    key: value  ; Not a comment, just part of the value

NOTE BENE -- that last is a BAD EXAMPLE of what is NOT supported. 
This module supports full-line comments only, not on same line with semantic content.

=head3 Sections

A configuration file consists of one or more I<sections>, each of which is
introduced by a label in square brackets:

    [SECTION1]        # Almost anything is a valid section label

    [SECTION 2]       # Internal whitespace is allowed (except newlines)

    [%^$%^&!!!]       # The label doesn't have to be alphanumeric

    [ETC. ETC. AS MANY AS YOU WANT]

The only restriction on section labels is that they must be by
themselves on a single line (except for any surrounding whitespace or
trailing comments), and they cannot contain the character C<]>.

Every line after a given section label until the next section label (or
the end of the config file) belongs to the given section label. If no
section label is currently in effect, the current section has an empty
label. In other words, there is an implicit:

    []                # Label is the empty string

at the start of each config file.

=head3 Configuration variables

Each non-empty line within a section must consist of the specification of a
I<configuration variable>. Each such variable consists of a key and a string
value. For example:

    name: George
     age: 47

    his weight! : 185

The key consists of every character (including internal whitespace) from
the start of the line until the key/value separator. So, the previous
example declares three keys: C<'name'>, C<'age'>, and C<'his weight!'>.

Note that whitespace before and after the key is removed. This makes it easier
to format keys cleanly:

           name : George
            age : 47
    his weight! : 185

The key/value separator can be either a colon (as above) or an equals sign,
like so:

           name= George
            age=  47
    his weight! = 185

Both types of separators can be used in the same file, but neither can
be used as part of a key. Newlines are not allowed in keys either.

When writing out a config file, Config::Std tries to preserve whichever
separator was used in the original data (if that data was read
in). New data 
(created by code not parsed by C<read_config>)
is written back with a colon as its default separator,
unless you specify the only other separator value C<'='> when the module is loaded:

    use Config::Std { def_sep => '=' };

Note that this does not change read-in parsing, 
does not change punctuation for values that were parsed, 
and will not allow values other than C<'='> or C<':'>.

Everything from the first non-whitespace character after the separator,
up to the end of the line, is treated as the value for the config variable.
So all of the above examples define the same three values: C<'George'>,
C<'47'>, and C<'185'>.

In other words, any whitespace immediately surrounding the separator
character is part of the separator, not part of the key or value.

Note that you can't put a comment on the same line as a configuration
variable. The C<# etc.> is simply considered part of the value:

    [Delimiters]

    block delims:    { }
    string delims:   " "
    comment delims:  # \n

You can comment a config var on the preceding or succeeding line:

    [Delimiters]

    # Use braces to delimit blocks...
    block delims:    { }

    # Use double quotes to delimit strings

    string delims:   " "

    # Use octothorpe/newline to delimit comments
    comment delims:  # \n
    

=head3 Multi-line configuration values

A single value can be continued over two or more lines. If the line
immediately after a configuration variable starts with the separator
character used in the variable's definition, then the value of the
variable continues on that line. For example:

    address: 742 Evergreen Terrace
           : Springfield
           : USA

The newlines then form part of the value, so the value specified in the
previous example is: C<S<"742 Evergreen Terrace\nSpringfield\nUSA">>

Note that the second and subsequent lines of a continued value are considered
to start where the whitespace after the I<original> separator finished, not
where the whitespace after their own separator finishes. For example, if the
previous example had been:

    address: 742 Evergreen Terrace
           :   Springfield
           :     USA

then the value would be:

    "742 Evergreen Terrace\n  Springfield\n    USA"

If a continuation line has less leading whitespace that the first line:

    address:   742 Evergreen Terrace
           :  Springfield
           : USA

it's treated as having no leading whitespace:

    "742 Evergreen Terrace\nSpringfield\nUSA"


=head3 Multi-part configuration values

If the particular key appears more than once in the same section, it is
considered to be part of the same configuration variable. The value of
that configuration value is then a list, containing all the individual
values for each instance of the key. For example, given the definition:

    cast: Homer
    cast: Marge
    cast: Lisa
    cast: Bart
    cast: Maggie

the corresponding value of the C<'cast'> configuration variable is:
C<S<['Homer', 'Marge', 'Lisa', 'Bart', 'Maggie']>>

Individual values in a multi-part list can also be multi-line (see
above). For example, given:

    extras: Moe
          : (the bartender)

    extras: Smithers
          : (the dogsbody)

the value for the C<'extras'> config variable is:
C<S<["Moe\n(the bartender)", "Smithers\n(the dogsbody)"]>>


=head2 Internal representation

Each section label in a configuration file becomes a top-level hash key whe
the configuration file is read in. The corresponding value is a nested hash
reference.

Each configuration variable's key becomes a key in that nested hash reference.
Each configuration variable's value becomes the corresponding value in that nested hash reference.

Single-line and multi-line values become strings. Multi-part values become
references to arrays of strings.

For example, the following configuration file:

    # A simple key (just an identifier)...
    simple : simple value

    # A more complex key (with whitespace)...
    more complex key : more complex value

    # A new section...
    [MULTI-WHATEVERS]

    # A value spread over several lines...
    multi-line : this is line 1
               : this is line 2
               : this is line 3

    # Several values for the same key...
    multi-value: this is value 1
    multi-value: this is value 2
    multi-value: this is value 3

would be read into a hash whose internal structure looked like this:

    {
       # Default section...
       '' => {
          'simple'           => 'simple value',
          'more complex key' => 'more complex value',
       },

       # Named section...
       'MULTI-WHATEVERS' => {
            'multi-line'  => "this is line 1\nthis is line 2\nthis is line 3",

            'multi-value' => [ 'this is value 1',
                               'this is value 2',
                               'this is value 3'
                             ],
        }
    }


=head1 INTERFACE 

The following subroutines are exported automatically whenever the module is
loaded...

=over 

=item C<< read_config($filename => %config_hash) >>

=item C<< read_config($filename => $config_hash_ref) >>

=item C<< read_config($string_ref => %config_hash_or_ref) >>

The C<read_config()> subroutine takes two arguments: the filename of a
configuration file, and a variable into which the contents of that
configuration file are to be loaded.

If the variable is a hash, then the configuration sections and their
key/value pairs are loaded into nested subhashes of the hash.

If the variable is a scalar with an undefined value, a reference to an
anonymous hash is first assigned to that scalar, and that hash is then
filled as described above.

The subroutine returns true on success, and throws an exception on failure.

If you pass a reference to the string as the first argument to
C<read_config()> it uses that string as the source of the config info.
For example:

	use Config::Std;

	# here we load the config text to a scalar
	my $cfg = q{
	[Section 1]
	attr1 = at
	attr2 = bat

	[Section 2]
	attr3 = cat
	};

	# here we parse the config from that scalar by passing a reference to it.
	read_config( \$cfg, my %config );

	use Data::Dumper 'Dumper';
	warn Dumper [ \%config ];


=item C<< write_config(%config_hash => $filename) >>

=item C<< write_config($config_hash_ref => $filename) >>

=item C<write_config(%config_hash)>

=item C<write_config($config_hash_ref)>

The C<write_config()> subroutine takes two arguments: the hash or hash
reference containing the configuration data to be written out to disk,
and an optional filename specifying which file it is to be written to.

The data hash must conform to the two-level structure described earlier:
with top-level keys naming sections and their values being references to
second-level hashes that store the keys and values of the configuartion
variables. If the structure of the hash differs from this, an exception is
thrown.

If a filename is also specified, the subroutine opens that file
and writes to it. It no filename is specified, the subroutine uses the
name of the file from which the hash was originally loaded using
C<read_config()>. It no filename is specified and the hash I<wasn't>
originally loaded using C<read_config()>, an exception is thrown.

The subroutine returns true on success and throws and exception on failure.

=back

If necessary (typically to avoid conflicts with other modules), you can
have the module export its two subroutines with different names by
loading it with the appropriate options:

    use Config::Std { read_config => 'get_ini', write_config => 'update_ini' };

    # and later...

    get_ini($filename => %config_hash);

    # and later still...

    update_ini(%config_hash);

You can also control how much spacing the module puts between single-
line values when they are first written to a file, by using the
C<def_gap> option:

    # No empty line between single-line config values...
    use Config::Std { def_gap => 0 }; 

    # An empty line between all single-line config values...
    use Config::Std { def_gap => 1 }; 

Regardless of the value passed for C<def_gap>, new multi-line values are
always written with an empty line above and below them. Likewise, values
that were previously read in from a file are always written back with
whatever spacing they originally had.

=head1 DIAGNOSTICS

=over 

=item Can't open config file '%s' (%s)

You tried to read in a configuration file, but the file you specified
didn't exist. Perhaps the filepath you specified was wrong. Or maybe 
your application didn't have permission to access the file you specified.

=item Can't read from locked config file '$filename'

You tried to read in a configuration file, but the file you specified
was being written by someone else (they had a file lock active on it).
Either try again later, or work out who else is using the file.

=item Scalar second argument to 'read_config' must be empty

You passed a scalar variable as the destination into C<read_config()>
was supposed to load a configuration file, but that variable already had
a defined value, so C<read_config()> couldn't autovivify a new hash for
you. Did you mean to pass the subroutine a hash instead of a scalar?

=item Can't save %s value for key '%s' (only scalars or array refs)

You called C<write_config> and passed it a hash containing a
configuration variable whose value wasn't a single string, or a list of
strings. The configuration file format supported by this module only
supports those two data types as values. If you really need to store
other kinds of data in a configuration file, you should consider using
C<Data::Dumper> or C<YAML> instead.

=item Missing filename in call to write_config()

You tried to calll C<write_config()> with only a configuration hash, but that
hash wasn't originally loaded using C<read_config()>, so C<write_config()> has
no idea where to write it to. Either make sure the hash you're trying to save
was originally loaded using C<read_config()>, or else provide an explicit
filename as the second argument to C<write_config()>.

=item Can't open config file '%s' for writing (%s)

You tried to update or create a configuration file, but the file you
specified could not be opened for writing (for the reason given in the
parentheses). This is often caused by incorrect filepaths or lack of
write permissions on a directory.

=item Can't write to locked config file '%s'

You tried to update or create a configuration file, but the file you
specified was being written at the time by someone else (they had a file
lock active on it). Either try again later, or work out who else is
using the file.

=back


=head1 CONFIGURATION AND ENVIRONMENT

Config::Std requires no configuration files or environment variables.
(To do so would be disturbingly recursive.)


=head1 DEPENDENCIES

This module requires the Class::Std module (available from the CPAN)


=head1 INCOMPATIBILITIES

Those variants of INI file dialect supporting partial-line comment are incompatible. 
(This is the price of keeping comments when re-writing.)


=head1 BUGS AND LIMITATIONS

=over

=item Loading on demand

If you attempt to load C<read_config()> and C<write_config()> 
at runtime with C<require>, you can not rely upon the prototype
to convert a regular hash to a reference. To work around this, 
you must explicitly pass a reference to the config hash.

    require Config::Std;
    Config::Std->import;

    my %config;
    read_config($file, \%config);
    write_config(\%config, $file);

=item Windows line endings on Unix/Linux (RT#21547/23550)

If the config file being read contains carriage returns and line feeds
at the end of each line rather than just line feeds (i.e. the standard
Windows file format, when read on a machine expecting POSIX file format),
Config::Std emits an error with embedded newline.

Workaround is match file line-endings to locale.

This will be fixed in 1.000.


=item leading comment vanishes (RT#24597,)

A comment before the first section is not always retained on write-back, if the '' default section is empty.

=item 00write.t test 5 fails on perl5.8.1 (RT#17425)

Due to an incompatible change in v5.8.1 partially reversed in v5.8.2, hash key randomisation can cause test to fail in that one version of Perl. Workaround is export environment variable PERL_HASH_SEED=0.

=back

Please report any bugs or feature requests to
C<bug-config-std@rt.cpan.org>, or through the web interface at
L<http://rt.cpan.org>.


=head1 AUTHOR

Damian Conway  C<< <DCONWAY@cpan.org> >>
Maintainers 
Bill Ricker    C<< <BRICKER@cpan.org> >>
Tom Metro      C<< <tmetro@cpan.org> >>

=head1 LICENCE AND COPYRIGHT

Copyright (c) 2005, Damian Conway C<< <DCONWAY@cpan.org> >>. 
Copyright (c) 2011, D.Conway, W.Ricker C<< <BRICKER@cpan.org> >> All rights reserved.

This module is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.


=head1 DISCLAIMER OF WARRANTY

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER
EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH
YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE
LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL,
OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE
THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF
SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
SUCH DAMAGES.