This file is indexed.

/usr/lib/ruby/2.3.0/rubygems.rb is in libruby2.3 2.3.3-1+deb9u2.

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
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
# frozen_string_literal: true
# -*- ruby -*-
#--
# Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
# All rights reserved.
# See LICENSE.txt for permissions.
#++

require 'rbconfig'
require 'thread'

module Gem
  VERSION = '2.5.2.1'
end

# Must be first since it unloads the prelude from 1.9.2
require 'rubygems/compatibility'

require 'rubygems/defaults'
require 'rubygems/deprecate'
require 'rubygems/errors'

##
# RubyGems is the Ruby standard for publishing and managing third party
# libraries.
#
# For user documentation, see:
#
# * <tt>gem help</tt> and <tt>gem help [command]</tt>
# * {RubyGems User Guide}[http://guides.rubygems.org/]
# * {Frequently Asked Questions}[http://guides.rubygems.org/faqs]
#
# For gem developer documentation see:
#
# * {Creating Gems}[http://guides.rubygems.org/make-your-own-gem]
# * Gem::Specification
# * Gem::Version for version dependency notes
#
# Further RubyGems documentation can be found at:
#
# * {RubyGems Guides}[http://guides.rubygems.org]
# * {RubyGems API}[http://rubygems.rubyforge.org/rdoc] (also available from
#   <tt>gem server</tt>)
#
# == RubyGems Plugins
#
# As of RubyGems 1.3.2, RubyGems will load plugins installed in gems or
# $LOAD_PATH.  Plugins must be named 'rubygems_plugin' (.rb, .so, etc) and
# placed at the root of your gem's #require_path.  Plugins are discovered via
# Gem::find_files then loaded.  Take care when implementing a plugin as your
# plugin file may be loaded multiple times if multiple versions of your gem
# are installed.
#
# For an example plugin, see the graph gem which adds a `gem graph` command.
#
# == RubyGems Defaults, Packaging
#
# RubyGems defaults are stored in rubygems/defaults.rb.  If you're packaging
# RubyGems or implementing Ruby you can change RubyGems' defaults.
#
# For RubyGems packagers, provide lib/rubygems/defaults/operating_system.rb
# and override any defaults from lib/rubygems/defaults.rb.
#
# For Ruby implementers, provide lib/rubygems/defaults/#{RUBY_ENGINE}.rb and
# override any defaults from lib/rubygems/defaults.rb.
#
# If you need RubyGems to perform extra work on install or uninstall, your
# defaults override file can set pre and post install and uninstall hooks.
# See Gem::pre_install, Gem::pre_uninstall, Gem::post_install,
# Gem::post_uninstall.
#
# == Bugs
#
# You can submit bugs to the
# {RubyGems bug tracker}[https://github.com/rubygems/rubygems/issues]
# on GitHub
#
# == Credits
#
# RubyGems is currently maintained by Eric Hodel.
#
# RubyGems was originally developed at RubyConf 2003 by:
#
# * Rich Kilmer  -- rich(at)infoether.com
# * Chad Fowler  -- chad(at)chadfowler.com
# * David Black  -- dblack(at)wobblini.net
# * Paul Brannan -- paul(at)atdesk.com
# * Jim Weirich   -- jim(at)weirichhouse.org
#
# Contributors:
#
# * Gavin Sinclair     -- gsinclair(at)soyabean.com.au
# * George Marrows     -- george.marrows(at)ntlworld.com
# * Dick Davies        -- rasputnik(at)hellooperator.net
# * Mauricio Fernandez -- batsman.geo(at)yahoo.com
# * Simon Strandgaard  -- neoneye(at)adslhome.dk
# * Dave Glasser       -- glasser(at)mit.edu
# * Paul Duncan        -- pabs(at)pablotron.org
# * Ville Aine         -- vaine(at)cs.helsinki.fi
# * Eric Hodel         -- drbrain(at)segment7.net
# * Daniel Berger      -- djberg96(at)gmail.com
# * Phil Hagelberg     -- technomancy(at)gmail.com
# * Ryan Davis         -- ryand-ruby(at)zenspider.com
# * Evan Phoenix       -- evan(at)fallingsnow.net
# * Steve Klabnik      -- steve(at)steveklabnik.com
#
# (If your name is missing, PLEASE let us know!)
#
# See {LICENSE.txt}[rdoc-ref:lib/rubygems/LICENSE.txt] for permissions.
#
# Thanks!
#
# -The RubyGems Team


module Gem
  RUBYGEMS_DIR = File.dirname File.expand_path(__FILE__)

  ##
  # An Array of Regexps that match windows Ruby platforms.

  WIN_PATTERNS = [
    /bccwin/i,
    /cygwin/i,
    /djgpp/i,
    /mingw/i,
    /mswin/i,
    /wince/i,
  ]

  GEM_DEP_FILES = %w[
    gem.deps.rb
    Gemfile
    Isolate
  ]

  ##
  # Subdirectories in a gem repository

  REPOSITORY_SUBDIRECTORIES = %w[
    build_info
    cache
    doc
    extensions
    gems
    specifications
  ]

  ##
  # Subdirectories in a gem repository for default gems

  REPOSITORY_DEFAULT_GEM_SUBDIRECTORIES = %w[
    gems
    specifications/default
  ]

  @@win_platform = nil

  @configuration = nil
  @gemdeps = nil
  @loaded_specs = {}
  LOADED_SPECS_MUTEX = Mutex.new
  @path_to_default_spec_map = {}
  @platforms = []
  @ruby = nil
  @ruby_api_version = nil
  @sources = nil

  @post_build_hooks     ||= []
  @post_install_hooks   ||= []
  @post_uninstall_hooks ||= []
  @pre_uninstall_hooks  ||= []
  @pre_install_hooks    ||= []
  @pre_reset_hooks      ||= []
  @post_reset_hooks     ||= []

  ##
  # Try to activate a gem containing +path+. Returns true if
  # activation succeeded or wasn't needed because it was already
  # activated. Returns false if it can't find the path in a gem.

  def self.try_activate path
    # finds the _latest_ version... regardless of loaded specs and their deps
    # if another gem had a requirement that would mean we shouldn't
    # activate the latest version, then either it would already be activated
    # or if it was ambiguous (and thus unresolved) the code in our custom
    # require will try to activate the more specific version.

    spec = Gem::Specification.find_by_path path
    return false unless spec
    return true if spec.activated?

    begin
      spec.activate
    rescue Gem::LoadError # this could fail due to gem dep collisions, go lax
      Gem::Specification.find_by_name(spec.name).activate
    end

    return true
  end

  def self.needs
    rs = Gem::RequestSet.new

    yield rs

    finish_resolve rs
  end

  def self.finish_resolve(request_set=Gem::RequestSet.new)
    request_set.import Gem::Specification.unresolved_deps.values

    request_set.resolve_current.each do |s|
      s.full_spec.activate
    end
  end

  ##
  # Find the full path to the executable for gem +name+.  If the +exec_name+
  # is not given, the gem's default_executable is chosen, otherwise the
  # specified executable's path is returned.  +requirements+ allows
  # you to specify specific gem versions.

  def self.bin_path(name, exec_name = nil, *requirements)
    # TODO: fails test_self_bin_path_bin_file_gone_in_latest
    # Gem::Specification.find_by_name(name, *requirements).bin_file exec_name

    raise ArgumentError, "you must supply exec_name" unless exec_name

    requirements = Gem::Requirement.default if
      requirements.empty?

    dep = Gem::Dependency.new name, requirements

    loaded = Gem.loaded_specs[name]

    return loaded.bin_file exec_name if loaded && dep.matches_spec?(loaded)

    specs = dep.matching_specs(true)

    raise Gem::GemNotFoundException,
          "can't find gem #{dep}" if specs.empty?

    specs = specs.find_all { |spec|
      spec.executables.include? exec_name
    } if exec_name

    unless spec = specs.last
      msg = "can't find gem #{name} (#{requirements}) with executable #{exec_name}"
      raise Gem::GemNotFoundException, msg
    end

    spec.bin_file exec_name
  end

  ##
  # The mode needed to read a file as straight binary.

  def self.binary_mode
    'rb'
  end

  ##
  # The path where gem executables are to be installed.

  def self.bindir(install_dir=Gem.dir)
    return File.join install_dir, 'bin' unless
      install_dir.to_s == Gem.default_dir.to_s
    Gem.default_bindir
  end

  ##
  # Reset the +dir+ and +path+ values.  The next time +dir+ or +path+
  # is requested, the values will be calculated from scratch.  This is
  # mainly used by the unit tests to provide test isolation.

  def self.clear_paths
    @paths         = nil
    @user_home     = nil
    Gem::Specification.reset
    Gem::Security.reset if defined?(Gem::Security)
  end

  ##
  # The path to standard location of the user's .gemrc file.

  def self.config_file
    @config_file ||= File.join Gem.user_home, '.gemrc'
  end

  ##
  # The standard configuration object for gems.

  def self.configuration
    @configuration ||= Gem::ConfigFile.new []
  end

  ##
  # Use the given configuration object (which implements the ConfigFile
  # protocol) as the standard configuration object.

  def self.configuration=(config)
    @configuration = config
  end

  ##
  # The path to the data directory specified by the gem name.  If the
  # package is not available as a gem, return nil.

  def self.datadir(gem_name)
# TODO: deprecate
    spec = @loaded_specs[gem_name]
    return nil if spec.nil?
    spec.datadir
  end

  ##
  # A Zlib::Deflate.deflate wrapper

  def self.deflate(data)
    require 'zlib'
    Zlib::Deflate.deflate data
  end

  # Retrieve the PathSupport object that RubyGems uses to
  # lookup files.

  def self.paths
    @paths ||= Gem::PathSupport.new
  end

  # Initialize the filesystem paths to use from +env+.
  # +env+ is a hash-like object (typically ENV) that
  # is queried for 'GEM_HOME', 'GEM_PATH', and 'GEM_SPEC_CACHE'

  def self.paths=(env)
    clear_paths
    @paths = Gem::PathSupport.new env
    Gem::Specification.dirs = @paths.path
  end

  ##
  # The path where gems are to be installed.
  #--
  # FIXME deprecate these once everything else has been done -ebh

  def self.dir
    paths.home
  end

  def self.path
    paths.path
  end

  def self.spec_cache_dir
    paths.spec_cache_dir
  end

  ##
  # Quietly ensure the Gem directory +dir+ contains all the proper
  # subdirectories.  If we can't create a directory due to a permission
  # problem, then we will silently continue.
  #
  # If +mode+ is given, missing directories are created with this mode.
  #
  # World-writable directories will never be created.

  def self.ensure_gem_subdirectories dir = Gem.dir, mode = nil
    ensure_subdirectories(dir, mode, REPOSITORY_SUBDIRECTORIES)
  end

  ##
  # Quietly ensure the Gem directory +dir+ contains all the proper
  # subdirectories for handling default gems.  If we can't create a
  # directory due to a permission problem, then we will silently continue.
  #
  # If +mode+ is given, missing directories are created with this mode.
  #
  # World-writable directories will never be created.

  def self.ensure_default_gem_subdirectories dir = Gem.dir, mode = nil
    ensure_subdirectories(dir, mode, REPOSITORY_DEFAULT_GEM_SUBDIRECTORIES)
  end

  def self.ensure_subdirectories dir, mode, subdirs # :nodoc:
    old_umask = File.umask
    File.umask old_umask | 002

    require 'fileutils'

    options = {}

    options[:mode] = mode if mode

    subdirs.each do |name|
      subdir = File.join dir, name
      next if File.exist? subdir
      FileUtils.mkdir_p subdir, options rescue nil
    end
  ensure
    File.umask old_umask
  end

  ##
  # The extension API version of ruby.  This includes the static vs non-static
  # distinction as extensions cannot be shared between the two.

  def self.extension_api_version # :nodoc:
    if 'no' == RbConfig::CONFIG['ENABLE_SHARED'] then
      "#{ruby_api_version}-static"
    else
      ruby_api_version
    end
  end

  ##
  # Returns a list of paths matching +glob+ that can be used by a gem to pick
  # up features from other gems.  For example:
  #
  #   Gem.find_files('rdoc/discover').each do |path| load path end
  #
  # if +check_load_path+ is true (the default), then find_files also searches
  # $LOAD_PATH for files as well as gems.
  #
  # Note that find_files will return all files even if they are from different
  # versions of the same gem.  See also find_latest_files

  def self.find_files(glob, check_load_path=true)
    files = []

    files = find_files_from_load_path glob if check_load_path

    files.concat Gem::Specification.stubs.map { |spec|
      spec.matches_for_glob("#{glob}#{Gem.suffix_pattern}")
    }.flatten

    # $LOAD_PATH might contain duplicate entries or reference
    # the spec dirs directly, so we prune.
    files.uniq! if check_load_path

    return files
  end

  def self.find_files_from_load_path glob # :nodoc:
    $LOAD_PATH.map { |load_path|
      Dir["#{File.expand_path glob, load_path}#{Gem.suffix_pattern}"]
    }.flatten.select { |file| File.file? file.untaint }
  end

  ##
  # Returns a list of paths matching +glob+ from the latest gems that can be
  # used by a gem to pick up features from other gems.  For example:
  #
  #   Gem.find_latest_files('rdoc/discover').each do |path| load path end
  #
  # if +check_load_path+ is true (the default), then find_latest_files also
  # searches $LOAD_PATH for files as well as gems.
  #
  # Unlike find_files, find_latest_files will return only files from the
  # latest version of a gem.

  def self.find_latest_files(glob, check_load_path=true)
    files = []

    files = find_files_from_load_path glob if check_load_path

    files.concat Gem::Specification.latest_specs(true).map { |spec|
      spec.matches_for_glob("#{glob}#{Gem.suffix_pattern}")
    }.flatten

    # $LOAD_PATH might contain duplicate entries or reference
    # the spec dirs directly, so we prune.
    files.uniq! if check_load_path

    return files
  end

  ##
  # Finds the user's home directory.
  #--
  # Some comments from the ruby-talk list regarding finding the home
  # directory:
  #
  #   I have HOME, USERPROFILE and HOMEDRIVE + HOMEPATH. Ruby seems
  #   to be depending on HOME in those code samples. I propose that
  #   it should fallback to USERPROFILE and HOMEDRIVE + HOMEPATH (at
  #   least on Win32).
  #++
  #--
  #
  # FIXME move to pathsupport
  #
  #++

  def self.find_home
    windows = File::ALT_SEPARATOR
    if not windows or RUBY_VERSION >= '1.9' then
      File.expand_path "~"
    else
      ['HOME', 'USERPROFILE'].each do |key|
        return File.expand_path ENV[key] if ENV[key]
      end

      if ENV['HOMEDRIVE'] && ENV['HOMEPATH'] then
        File.expand_path "#{ENV['HOMEDRIVE']}#{ENV['HOMEPATH']}"
      end
    end
  rescue
    if windows then
      File.expand_path File.join(ENV['HOMEDRIVE'] || ENV['SystemDrive'], '/')
    else
      File.expand_path "/"
    end
  end

  private_class_method :find_home

  # FIXME deprecate these in 3.0

  ##
  # Zlib::GzipReader wrapper that unzips +data+.

  def self.gunzip(data)
    require 'rubygems/util'
    Gem::Util.gunzip data
  end

  ##
  # Zlib::GzipWriter wrapper that zips +data+.

  def self.gzip(data)
    require 'rubygems/util'
    Gem::Util.gzip data
  end

  ##
  # A Zlib::Inflate#inflate wrapper

  def self.inflate(data)
    require 'rubygems/util'
    Gem::Util.inflate data
  end

  ##
  # Top level install helper method. Allows you to install gems interactively:
  #
  #   % irb
  #   >> Gem.install "minitest"
  #   Fetching: minitest-3.0.1.gem (100%)
  #   => [#<Gem::Specification:0x1013b4528 @name="minitest", ...>]

  def self.install name, version = Gem::Requirement.default, *options
    require "rubygems/dependency_installer"
    inst = Gem::DependencyInstaller.new(*options)
    inst.install name, version
    inst.installed_gems
  end

  ##
  # Get the default RubyGems API host. This is normally
  # <tt>https://rubygems.org</tt>.

  def self.host
    # TODO: move to utils
    @host ||= Gem::DEFAULT_HOST
  end

  ## Set the default RubyGems API host.

  def self.host= host
    # TODO: move to utils
    @host = host
  end

  ##
  # The index to insert activated gem paths into the $LOAD_PATH. The activated
  # gem's paths are inserted before site lib directory by default.

  def self.load_path_insert_index
    $LOAD_PATH.each_with_index do |path, i|
      return i if path.instance_variable_defined?(:@gem_prelude_index)
    end

    index = $LOAD_PATH.index RbConfig::CONFIG['sitelibdir']

    index
  end

  @yaml_loaded = false

  ##
  # Loads YAML, preferring Psych

  def self.load_yaml
    return if @yaml_loaded
    return unless defined?(gem)

    test_syck = ENV['TEST_SYCK']

    # Only Ruby 1.8 and 1.9 have syck
    test_syck = false unless /^1\./ =~ RUBY_VERSION

    unless test_syck
      begin
        gem 'psych', '>= 2.0.0'
      rescue Gem::LoadError
        # It's OK if the user does not have the psych gem installed.  We will
        # attempt to require the stdlib version
      end

      begin
        # Try requiring the gem version *or* stdlib version of psych.
        require 'psych'
      rescue ::LoadError
        # If we can't load psych, thats fine, go on.
      else
        # If 'yaml' has already been required, then we have to
        # be sure to switch it over to the newly loaded psych.
        if defined?(YAML::ENGINE) && YAML::ENGINE.yamler != "psych"
          YAML::ENGINE.yamler = "psych"
        end

        require 'rubygems/psych_additions'
        require 'rubygems/psych_tree'
      end
    end

    require 'yaml'
    require 'rubygems/safe_yaml'

    # If we're supposed to be using syck, then we may have to force
    # activate it via the YAML::ENGINE API.
    if test_syck and defined?(YAML::ENGINE)
      YAML::ENGINE.yamler = "syck" unless YAML::ENGINE.syck?
    end

    # Now that we're sure some kind of yaml library is loaded, pull
    # in our hack to deal with Syck's DefaultKey ugliness.
    require 'rubygems/syck_hack'

    @yaml_loaded = true
  end

  ##
  # The file name and line number of the caller of the caller of this method.

  def self.location_of_caller
    caller[1] =~ /(.*?):(\d+).*?$/i
    file = $1
    lineno = $2.to_i

    [file, lineno]
  end

  ##
  # The version of the Marshal format for your Ruby.

  def self.marshal_version
    "#{Marshal::MAJOR_VERSION}.#{Marshal::MINOR_VERSION}"
  end

  ##
  # Set array of platforms this RubyGems supports (primarily for testing).

  def self.platforms=(platforms)
    @platforms = platforms
  end

  ##
  # Array of platforms this RubyGems supports.

  def self.platforms
    @platforms ||= []
    if @platforms.empty?
      @platforms = [Gem::Platform::RUBY, Gem::Platform.local]
    end
    @platforms
  end

  ##
  # Adds a post-build hook that will be passed an Gem::Installer instance
  # when Gem::Installer#install is called.  The hook is called after the gem
  # has been extracted and extensions have been built but before the
  # executables or gemspec has been written.  If the hook returns +false+ then
  # the gem's files will be removed and the install will be aborted.

  def self.post_build(&hook)
    @post_build_hooks << hook
  end

  ##
  # Adds a post-install hook that will be passed an Gem::Installer instance
  # when Gem::Installer#install is called

  def self.post_install(&hook)
    @post_install_hooks << hook
  end

  ##
  # Adds a post-installs hook that will be passed a Gem::DependencyInstaller
  # and a list of installed specifications when
  # Gem::DependencyInstaller#install is complete

  def self.done_installing(&hook)
    @done_installing_hooks << hook
  end

  ##
  # Adds a hook that will get run after Gem::Specification.reset is
  # run.

  def self.post_reset(&hook)
    @post_reset_hooks << hook
  end

  ##
  # Adds a post-uninstall hook that will be passed a Gem::Uninstaller instance
  # and the spec that was uninstalled when Gem::Uninstaller#uninstall is
  # called

  def self.post_uninstall(&hook)
    @post_uninstall_hooks << hook
  end

  ##
  # Adds a pre-install hook that will be passed an Gem::Installer instance
  # when Gem::Installer#install is called.  If the hook returns +false+ then
  # the install will be aborted.

  def self.pre_install(&hook)
    @pre_install_hooks << hook
  end

  ##
  # Adds a hook that will get run before Gem::Specification.reset is
  # run.

  def self.pre_reset(&hook)
    @pre_reset_hooks << hook
  end

  ##
  # Adds a pre-uninstall hook that will be passed an Gem::Uninstaller instance
  # and the spec that will be uninstalled when Gem::Uninstaller#uninstall is
  # called

  def self.pre_uninstall(&hook)
    @pre_uninstall_hooks << hook
  end

  ##
  # The directory prefix this RubyGems was installed at. If your
  # prefix is in a standard location (ie, rubygems is installed where
  # you'd expect it to be), then prefix returns nil.

  def self.prefix
    prefix = File.dirname RUBYGEMS_DIR

    if prefix != File.expand_path(RbConfig::CONFIG['sitelibdir']) and
       prefix != File.expand_path(RbConfig::CONFIG['libdir']) and
       'lib' == File.basename(RUBYGEMS_DIR) then
      prefix
    end
  end

  ##
  # Refresh available gems from disk.

  def self.refresh
    Gem::Specification.reset
  end

  ##
  # Safely read a file in binary mode on all platforms.

  def self.read_binary(path)
    open path, 'rb+' do |f|
      f.flock(File::LOCK_EX)
      f.read
    end
  rescue Errno::EACCES
    open path, 'rb' do |f|
      f.read
    end
  rescue Errno::ENOLCK # NFS
    if Thread.main != Thread.current
      raise
    else
      open path, 'rb' do |f|
        f.read
      end
    end
  end

  ##
  # The path to the running Ruby interpreter.

  def self.ruby
    if @ruby.nil? then
      @ruby = File.join(RbConfig::CONFIG['bindir'],
                        "#{RbConfig::CONFIG['ruby_install_name']}#{RbConfig::CONFIG['EXEEXT']}")

      @ruby = "\"#{@ruby}\"" if @ruby =~ /\s/
    end

    @ruby
  end

  ##
  # Returns a String containing the API compatibility version of Ruby

  def self.ruby_api_version
    @ruby_api_version ||= RbConfig::CONFIG['ruby_version'].dup
  end

  ##
  # Returns the latest release-version specification for the gem +name+.

  def self.latest_spec_for name
    dependency   = Gem::Dependency.new name
    fetcher      = Gem::SpecFetcher.fetcher
    spec_tuples, = fetcher.spec_for_dependency dependency

    spec, = spec_tuples.first

    spec
  end

  ##
  # Returns the latest release version of RubyGems.

  def self.latest_rubygems_version
    latest_version_for('rubygems-update') or
      raise "Can't find 'rubygems-update' in any repo. Check `gem source list`."
  end

  ##
  # Returns the version of the latest release-version of gem +name+

  def self.latest_version_for name
    spec = latest_spec_for name
    spec and spec.version
  end

  ##
  # A Gem::Version for the currently running Ruby.

  def self.ruby_version
    return @ruby_version if defined? @ruby_version
    version = RUBY_VERSION.dup

    if defined?(RUBY_PATCHLEVEL) && RUBY_PATCHLEVEL != -1 then
      version << ".#{RUBY_PATCHLEVEL}"
    elsif defined?(RUBY_REVISION) then
      version << ".dev.#{RUBY_REVISION}"
    end

    @ruby_version = Gem::Version.new version
  end

  ##
  # A Gem::Version for the currently running RubyGems

  def self.rubygems_version
    return @rubygems_version if defined? @rubygems_version
    @rubygems_version = Gem::Version.new Gem::VERSION
  end

  ##
  # Returns an Array of sources to fetch remote gems from. Uses
  # default_sources if the sources list is empty.

  def self.sources
    @sources ||= Gem::SourceList.from(default_sources)
  end

  ##
  # Need to be able to set the sources without calling
  # Gem.sources.replace since that would cause an infinite loop.
  #
  # DOC: This comment is not documentation about the method itself, it's
  # more of a code comment about the implementation.

  def self.sources= new_sources
    if !new_sources
      @sources = nil
    else
      @sources = Gem::SourceList.from(new_sources)
    end
  end

  ##
  # Glob pattern for require-able path suffixes.

  def self.suffix_pattern
    @suffix_pattern ||= "{#{suffixes.join(',')}}"
  end

  ##
  # Suffixes for require-able paths.

  def self.suffixes
    @suffixes ||= ['',
                   '.rb',
                   *%w(DLEXT DLEXT2).map { |key|
                     val = RbConfig::CONFIG[key]
                     next unless val and not val.empty?
                     ".#{val}"
                   }
                  ].compact.uniq
  end

  ##
  # Prints the amount of time the supplied block takes to run using the debug
  # UI output.

  def self.time(msg, width = 0, display = Gem.configuration.verbose)
    now = Time.now

    value = yield

    elapsed = Time.now - now

    ui.say "%2$*1$s: %3$3.3fs" % [-width, msg, elapsed] if display

    value
  end

  ##
  # Lazily loads DefaultUserInteraction and returns the default UI.

  def self.ui
    require 'rubygems/user_interaction'

    Gem::DefaultUserInteraction.ui
  end

  ##
  # Use the +home+ and +paths+ values for Gem.dir and Gem.path.  Used mainly
  # by the unit tests to provide environment isolation.

  def self.use_paths(home, *paths)
    paths = nil if paths == [nil]
    paths = paths.first if Array === Array(paths).first
    self.paths = { "GEM_HOME" => home, "GEM_PATH" => paths }
  end

  ##
  # The home directory for the user.

  def self.user_home
    @user_home ||= find_home.untaint
  end

  ##
  # Is this a windows platform?

  def self.win_platform?
    if @@win_platform.nil? then
      ruby_platform = RbConfig::CONFIG['host_os']
      @@win_platform = !!WIN_PATTERNS.find { |r| ruby_platform =~ r }
    end

    @@win_platform
  end

  ##
  # Load +plugins+ as Ruby files

  def self.load_plugin_files plugins # :nodoc:
    plugins.each do |plugin|

      # Skip older versions of the GemCutter plugin: Its commands are in
      # RubyGems proper now.

      next if plugin =~ /gemcutter-0\.[0-3]/

      begin
        load plugin
      rescue ::Exception => e
        details = "#{plugin.inspect}: #{e.message} (#{e.class})"
        warn "Error loading RubyGems plugin #{details}"
      end
    end
  end

  ##
  # Find the 'rubygems_plugin' files in the latest installed gems and load
  # them

  def self.load_plugins
    # Remove this env var by at least 3.0
    if ENV['RUBYGEMS_LOAD_ALL_PLUGINS']
      load_plugin_files find_files('rubygems_plugin', false)
    else
      load_plugin_files find_latest_files('rubygems_plugin', false)
    end
  end

  ##
  # Find all 'rubygems_plugin' files in $LOAD_PATH and load them

  def self.load_env_plugins
    path = "rubygems_plugin"

    files = []
    $LOAD_PATH.each do |load_path|
      globbed = Dir["#{File.expand_path path, load_path}#{Gem.suffix_pattern}"]

      globbed.each do |load_path_file|
        files << load_path_file if File.file?(load_path_file.untaint)
      end
    end

    load_plugin_files files
  end

  ##
  # Looks for a gem dependency file at +path+ and activates the gems in the
  # file if found.  If the file is not found an ArgumentError is raised.
  #
  # If +path+ is not given the RUBYGEMS_GEMDEPS environment variable is used,
  # but if no file is found no exception is raised.
  #
  # If '-' is given for +path+ RubyGems searches up from the current working
  # directory for gem dependency files (gem.deps.rb, Gemfile, Isolate) and
  # activates the gems in the first one found.
  #
  # You can run this automatically when rubygems starts.  To enable, set
  # the <code>RUBYGEMS_GEMDEPS</code> environment variable to either the path
  # of your gem dependencies file or "-" to auto-discover in parent
  # directories.
  #
  # NOTE: Enabling automatic discovery on multiuser systems can lead to
  # execution of arbitrary code when used from directories outside your
  # control.

  def self.use_gemdeps path = nil
    raise_exception = path

    path ||= ENV['RUBYGEMS_GEMDEPS']
    return unless path

    path = path.dup

    if path == "-" then
      require 'rubygems/util'

      Gem::Util.traverse_parents Dir.pwd do |directory|
        dep_file = GEM_DEP_FILES.find { |f| File.file?(f) }

        next unless dep_file

        path = File.join directory, dep_file
        break
      end
    end

    path.untaint

    unless File.file? path then
      return unless raise_exception

      raise ArgumentError, "Unable to find gem dependencies file at #{path}"
    end

    rs = Gem::RequestSet.new
    @gemdeps = rs.load_gemdeps path

    rs.resolve_current.map do |s|
      sp = s.full_spec
      sp.activate
      sp
    end
  rescue Gem::LoadError, Gem::UnsatisfiableDependencyError => e
    warn e.message
    warn "You may need to `gem install -g` to install missing gems"
    warn ""
  end

  class << self
    ##
    # TODO remove with RubyGems 3.0

    alias detect_gemdeps use_gemdeps # :nodoc:
  end

  # FIX: Almost everywhere else we use the `def self.` way of defining class
  # methods, and then we switch over to `class << self` here. Pick one or the
  # other.
  class << self

    ##
    # Hash of loaded Gem::Specification keyed by name

    attr_reader :loaded_specs

    ##
    # GemDependencyAPI object, which is set when .use_gemdeps is called.
    # This contains all the information from the Gemfile.

    attr_reader :gemdeps

    ##
    # Register a Gem::Specification for default gem.
    #
    # Two formats for the specification are supported:
    #
    # * MRI 2.0 style, where spec.files contains unprefixed require names.
    #   The spec's filenames will be registered as-is.
    # * New style, where spec.files contains files prefixed with paths
    #   from spec.require_paths. The prefixes are stripped before
    #   registering the spec's filenames. Unprefixed files are omitted.
    #

    def register_default_spec(spec)
      new_format = Gem.default_gems_use_full_paths? || spec.require_paths.any? {|path| spec.files.any? {|f| f.start_with? path } }

      if new_format
        prefix_group = spec.require_paths.map {|f| f + "/"}.join("|")
        prefix_pattern = /^(#{prefix_group})/
      end

      spec.files.each do |file|
        if new_format
          file = file.sub(prefix_pattern, "")
          next unless $~
        end

        @path_to_default_spec_map[file] = spec
      end
    end

    ##
    # Find a Gem::Specification of default gem from +path+

    def find_unresolved_default_spec(path)
      Gem.suffixes.each do |suffix|
        spec = @path_to_default_spec_map["#{path}#{suffix}"]
        return spec if spec
      end
      nil
    end

    ##
    # Remove needless Gem::Specification of default gem from
    # unresolved default gem list

    def remove_unresolved_default_spec(spec)
      spec.files.each do |file|
        @path_to_default_spec_map.delete(file)
      end
    end

    ##
    # Clear default gem related variables. It is for test

    def clear_default_specs
      @path_to_default_spec_map.clear
    end

    ##
    # The list of hooks to be run after Gem::Installer#install extracts files
    # and builds extensions

    attr_reader :post_build_hooks

    ##
    # The list of hooks to be run after Gem::Installer#install completes
    # installation

    attr_reader :post_install_hooks

    ##
    # The list of hooks to be run after Gem::DependencyInstaller installs a
    # set of gems

    attr_reader :done_installing_hooks

    ##
    # The list of hooks to be run after Gem::Specification.reset is run.

    attr_reader :post_reset_hooks

    ##
    # The list of hooks to be run after Gem::Uninstaller#uninstall completes
    # installation

    attr_reader :post_uninstall_hooks

    ##
    # The list of hooks to be run before Gem::Installer#install does any work

    attr_reader :pre_install_hooks

    ##
    # The list of hooks to be run before Gem::Specification.reset is run.

    attr_reader :pre_reset_hooks

    ##
    # The list of hooks to be run before Gem::Uninstaller#uninstall does any
    # work

    attr_reader :pre_uninstall_hooks
  end

  ##
  # Location of Marshal quick gemspecs on remote repositories

  MARSHAL_SPEC_DIR = "quick/Marshal.#{Gem.marshal_version}/"

  autoload :ConfigFile,         'rubygems/config_file'
  autoload :Dependency,         'rubygems/dependency'
  autoload :DependencyList,     'rubygems/dependency_list'
  autoload :DependencyResolver, 'rubygems/resolver'
  autoload :Installer,          'rubygems/installer'
  autoload :Licenses,           'rubygems/util/licenses'
  autoload :PathSupport,        'rubygems/path_support'
  autoload :Platform,           'rubygems/platform'
  autoload :RequestSet,         'rubygems/request_set'
  autoload :Requirement,        'rubygems/requirement'
  autoload :Resolver,           'rubygems/resolver'
  autoload :Source,             'rubygems/source'
  autoload :SourceList,         'rubygems/source_list'
  autoload :SpecFetcher,        'rubygems/spec_fetcher'
  autoload :Specification,      'rubygems/specification'
  autoload :Version,            'rubygems/version'

  require "rubygems/specification"
end

require 'rubygems/exceptions'

# REFACTOR: This should be pulled out into some kind of hacks file.
gem_preluded = Gem::GEM_PRELUDE_SUCKAGE and defined? Gem
unless gem_preluded then # TODO: remove guard after 1.9.2 dropped
  begin
    ##
    # Defaults the operating system (or packager) wants to provide for RubyGems.

    require 'rubygems/defaults/operating_system'
  rescue LoadError
  end

  if defined?(RUBY_ENGINE) then
    begin
      ##
      # Defaults the Ruby implementation wants to provide for RubyGems

      require "rubygems/defaults/#{RUBY_ENGINE}"
    rescue LoadError
    end
  end
end

##
# Loads the default specs.
Gem::Specification.load_defaults

require 'rubygems/core_ext/kernel_gem'
require 'rubygems/core_ext/kernel_require'

Gem.use_gemdeps