summaryrefslogtreecommitdiff
path: root/lib/rubygems/core_ext/kernel_require.rb
blob: faf9886d78da74d613d570f3392a7b3dbd55b4c0 (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
# frozen_string_literal: true
#--
# Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
# All rights reserved.
# See LICENSE.txt for permissions.
#++

require 'monitor'

module Kernel

  RUBYGEMS_ACTIVATION_MONITOR = Monitor.new # :nodoc:

  # Make sure we have a reference to Ruby's original Kernel#require
  unless defined?(gem_original_require)
    alias gem_original_require require
    private :gem_original_require
  end

  ##
  # When RubyGems is required, Kernel#require is replaced with our own which
  # is capable of loading gems on demand.
  #
  # When you call <tt>require 'x'</tt>, this is what happens:
  # * If the file can be loaded from the existing Ruby loadpath, it
  #   is.
  # * Otherwise, installed gems are searched for a file that matches.
  #   If it's found in gem 'y', that gem is activated (added to the
  #   loadpath).
  #
  # The normal <tt>require</tt> functionality of returning false if
  # that file has already been loaded is preserved.

  def require(path)
    if RUBYGEMS_ACTIVATION_MONITOR.respond_to?(:mon_owned?)
      monitor_owned = RUBYGEMS_ACTIVATION_MONITOR.mon_owned?
    end
    RUBYGEMS_ACTIVATION_MONITOR.enter

    path = path.to_path if path.respond_to? :to_path

    if spec = Gem.find_unresolved_default_spec(path)
      # Ensure -I beats a default gem
      resolved_path = begin
        rp = nil
        load_path_check_index = Gem.load_path_insert_index - Gem.activated_gem_paths
        Gem.suffixes.each do |s|
          $LOAD_PATH[0...load_path_check_index].each do |lp|
            safe_lp = lp.dup.tap(&Gem::UNTAINT)
            begin
              if File.symlink? safe_lp # for backward compatibility
                next
              end
            rescue SecurityError
              RUBYGEMS_ACTIVATION_MONITOR.exit
              raise
            end

            full_path = File.expand_path(File.join(safe_lp, "#{path}#{s}"))
            if File.file?(full_path)
              rp = full_path
              break
            end
          end
          break if rp
        end
        rp
      end

      begin
        Kernel.send(:gem, spec.name, Gem::Requirement.default_prerelease)
      rescue Exception
        RUBYGEMS_ACTIVATION_MONITOR.exit
        raise
      end unless resolved_path
    end

    # If there are no unresolved deps, then we can use just try
    # normal require handle loading a gem from the rescue below.

    if Gem::Specification.unresolved_deps.empty?
      RUBYGEMS_ACTIVATION_MONITOR.exit
      return gem_original_require(path)
    end

    # If +path+ is for a gem that has already been loaded, don't
    # bother trying to find it in an unresolved gem, just go straight
    # to normal require.
    #--
    # TODO request access to the C implementation of this to speed up RubyGems

    if Gem::Specification.find_active_stub_by_path(path)
      RUBYGEMS_ACTIVATION_MONITOR.exit
      return gem_original_require(path)
    end

    # Attempt to find +path+ in any unresolved gems...

    found_specs = Gem::Specification.find_in_unresolved path

    # If there are no directly unresolved gems, then try and find +path+
    # in any gems that are available via the currently unresolved gems.
    # For example, given:
    #
    #   a => b => c => d
    #
    # If a and b are currently active with c being unresolved and d.rb is
    # requested, then find_in_unresolved_tree will find d.rb in d because
    # it's a dependency of c.
    #
    if found_specs.empty?
      found_specs = Gem::Specification.find_in_unresolved_tree path

      found_specs.each do |found_spec|
        found_spec.activate
      end

    # We found +path+ directly in an unresolved gem. Now we figure out, of
    # the possible found specs, which one we should activate.
    else

      # Check that all the found specs are just different
      # versions of the same gem
      names = found_specs.map(&:name).uniq

      if names.size > 1
        RUBYGEMS_ACTIVATION_MONITOR.exit
        raise Gem::LoadError, "#{path} found in multiple gems: #{names.join ', '}"
      end

      # Ok, now find a gem that has no conflicts, starting
      # at the highest version.
      valid = found_specs.find { |s| !s.has_conflicts? }

      unless valid
        le = Gem::LoadError.new "unable to find a version of '#{names.first}' to activate"
        le.name = names.first
        RUBYGEMS_ACTIVATION_MONITOR.exit
        raise le
      end

      valid.activate
    end

    RUBYGEMS_ACTIVATION_MONITOR.exit
    return gem_original_require(path)
  rescue LoadError => load_error
    RUBYGEMS_ACTIVATION_MONITOR.enter

    begin
      if load_error.path == path and Gem.try_activate(path)
        require_again = true
      end
    ensure
      RUBYGEMS_ACTIVATION_MONITOR.exit
    end

    return gem_original_require(path) if require_again

    raise load_error
  ensure
    if RUBYGEMS_ACTIVATION_MONITOR.respond_to?(:mon_owned?)
      if monitor_owned != (ow = RUBYGEMS_ACTIVATION_MONITOR.mon_owned?)
        STDERR.puts [$$, Thread.current, $!, $!.backtrace].inspect if $!
        raise "CRITICAL: RUBYGEMS_ACTIVATION_MONITOR.owned?: before #{monitor_owned} -> after #{ow}"
      end
    end
  end

  private :require

end