1 files changed, 21 insertions, 9 deletions
diff --git a/lib/rubygems/defaults.rb b/lib/rubygems/defaults.rb
index 7888e8cee5..1bd208feb9 100644
--- a/lib/rubygems/defaults.rb
+++ b/lib/rubygems/defaults.rb
@@ -24,7 +24,7 @@ module Gem
     default_spec_cache_dir = File.join Gem.user_home, ".gem", "specs"
 
     unless File.exist?(default_spec_cache_dir)
-      default_spec_cache_dir = File.join Gem.data_home, "gem", "specs"
+      default_spec_cache_dir = File.join Gem.cache_home, "gem", "specs"
     end
 
     default_spec_cache_dir
@@ -94,7 +94,7 @@ module Gem
   # The home directory for the user.
 
   def self.user_home
-    @user_home ||= find_home.tap(&Gem::UNTAINT)
+    @user_home ||= find_home
   end
 
   ##
@@ -112,7 +112,7 @@ module Gem
   # The path to standard location of the user's configuration directory.
 
   def self.config_home
-    @config_home ||= (ENV["XDG_CONFIG_HOME"] || File.join(Gem.user_home, ".config"))
+    @config_home ||= ENV["XDG_CONFIG_HOME"] || File.join(Gem.user_home, ".config")
   end
 
   ##
@@ -131,35 +131,35 @@ module Gem
   # The path to standard location of the user's .gemrc file.
 
   def self.config_file
-    @config_file ||= find_config_file.tap(&Gem::UNTAINT)
+    @config_file ||= find_config_file
   end
 
   ##
   # The path to standard location of the user's state file.
 
   def self.state_file
-    @state_file ||= File.join(Gem.state_home, "gem", "last_update_check").tap(&Gem::UNTAINT)
+    @state_file ||= File.join(Gem.state_home, "gem", "last_update_check")
   end
 
   ##
   # The path to standard location of the user's cache directory.
 
   def self.cache_home
-    @cache_home ||= (ENV["XDG_CACHE_HOME"] || File.join(Gem.user_home, ".cache"))
+    @cache_home ||= ENV["XDG_CACHE_HOME"] || File.join(Gem.user_home, ".cache")
   end
 
   ##
   # The path to standard location of the user's data directory.
 
   def self.data_home
-    @data_home ||= (ENV["XDG_DATA_HOME"] || File.join(Gem.user_home, ".local", "share"))
+    @data_home ||= ENV["XDG_DATA_HOME"] || File.join(Gem.user_home, ".local", "share")
   end
 
   ##
   # The path to standard location of the user's state directory.
 
   def self.state_home
-    @state_home ||= (ENV["XDG_STATE_HOME"] || File.join(Gem.user_home, ".local", "state"))
+    @state_home ||= ENV["XDG_STATE_HOME"] || File.join(Gem.user_home, ".local", "state")
   end
 
   ##
@@ -236,10 +236,22 @@ module Gem
   end
 
   ##
+  # Enables automatic installation into user directory
+
+  def self.default_user_install # :nodoc:
+    if !ENV.key?("GEM_HOME") && (File.exist?(Gem.dir) && !File.writable?(Gem.dir))
+      Gem.ui.say "Defaulting to user installation because default installation directory (#{Gem.dir}) is not writable."
+      return true
+    end
+
+    false
+  end
+
+  ##
   # Install extensions into lib as well as into the extension directory.
 
   def self.install_extension_in_lib # :nodoc:
-    true
+    Gem.configuration.install_extension_in_lib
   end
 
   ##