Auto merge of #5421 - bundler:seg-read-only-fs-no-global-settings, r=indirect

Don't read global settings on a read-only FS with no $HOME

Closes https://github.com/bundler/bundler/issues/5371
This is an alternative to https://github.com/bundler/bundler/pull/5385

(cherry picked from commit 42b1e1b9c3f4b3a45cd27214ef656911951b4d94)

6 files changed, 25 insertions, 3 deletions

diff --git a/lib/bundler.rb b/lib/bundler.rb
index c98dece747..914bdb3762 100644
--- a/lib/bundler.rb
+++ b/lib/bundler.rb
@@ -176,7 +176,7 @@ module Bundler
         tmp_home_path.join(login).tap(&:mkpath)
       end
     rescue => e
-      raise "#{warning}\nBundler also failed to create a temporary home directory at `#{path}':\n#{e}"
+      raise e.exception("#{warning}\nBundler also failed to create a temporary home directory at `#{path}':\n#{e}")
     end
 
     def user_bundle_path
diff --git a/lib/bundler/settings.rb b/lib/bundler/settings.rb
index 0aa9082352..411b85296f 100644
--- a/lib/bundler/settings.rb
+++ b/lib/bundler/settings.rb
@@ -284,7 +284,11 @@ module Bundler
       if ENV["BUNDLE_CONFIG"] && !ENV["BUNDLE_CONFIG"].empty?
         Pathname.new(ENV["BUNDLE_CONFIG"])
       else
-        Bundler.user_bundle_path.join("config")
+        begin
+          Bundler.user_bundle_path.join("config")
+        rescue PermissionError, GenericSystemCallError
+          nil
+        end
       end
     end
 
diff --git a/spec/bundler/settings_spec.rb b/spec/bundler/settings_spec.rb
index 04e221a57c..32e1fb7626 100644
--- a/spec/bundler/settings_spec.rb
+++ b/spec/bundler/settings_spec.rb
@@ -62,6 +62,19 @@ that would suck --ehhh=oh geez it looks like i might have broken bundler somehow
     end
   end
 
+  describe "#global_config_file" do
+    context "when $HOME is not accessible" do
+      context "when $TMPDIR is not writable" do
+        it "does not raise" do
+          expect(Bundler.rubygems).to receive(:user_home).twice.and_return(nil)
+          expect(FileUtils).to receive(:mkpath).twice.with(File.join(Dir.tmpdir, "bundler", "home")).and_raise(Errno::EROFS, "Read-only file system @ dir_s_mkdir - /tmp/bundler")
+
+          expect(subject.send(:global_config_file)).to be_nil
+        end
+      end
+    end
+  end
+
   describe "#[]" do
     context "when the local config file is not found" do
       subject(:settings) { described_class.new }
diff --git a/spec/support/helpers.rb b/spec/support/helpers.rb
index 815671bba5..8095331b0a 100644
--- a/spec/support/helpers.rb
+++ b/spec/support/helpers.rb
@@ -10,8 +10,8 @@ module Spec
           FileUtils.rm_rf(dir)
         end
       end
-      FileUtils.mkdir_p(tmp)
       FileUtils.mkdir_p(home)
+      FileUtils.mkdir_p(tmpdir)
       ENV["BUNDLE_TRAMPOLINE_DISABLE"] = "1"
       Bundler.reset!
       Bundler.ui = nil
diff --git a/spec/support/path.rb b/spec/support/path.rb
index cf77adb509..2b929003fb 100644
--- a/spec/support/path.rb
+++ b/spec/support/path.rb
@@ -89,6 +89,10 @@ module Spec
       bundled_app ".bundle", "plugin", "gems", *args
     end
 
+    def tmpdir(*args)
+      tmp "tmpdir", *args
+    end
+
     extend self
   end
 end
diff --git a/spec/support/rubygems_ext.rb b/spec/support/rubygems_ext.rb
index b75350f473..88886c3f1f 100644
--- a/spec/support/rubygems_ext.rb
+++ b/spec/support/rubygems_ext.rb
@@ -42,6 +42,7 @@ module Spec
       end
 
       ENV["HOME"] = Path.home.to_s
+      ENV["TMPDIR"] = Path.tmpdir.to_s
 
       Gem::DefaultUserInteraction.ui = Gem::SilentUI.new
     end