Introduce `Psych.unsafe_load`

In future versions of Psych, the `load` method will be mostly the same
as the `safe_load` method.  In other words, the `load` method won't
allow arbitrary object deserialization (which can be used to escalate to
an RCE).  People that need to load *trusted* documents can use the
`unsafe_load` method.

This commit introduces the `unsafe_load` method so that people can
incrementally upgrade.  For example, if they try to upgrade to 4.0.0 and
something breaks, they can downgrade, audit callsites, change to
`safe_load` or `unsafe_load` as required, and then upgrade to 4.0.0
smoothly.

1 files changed, 30 insertions, 15 deletions

diff --git a/test/psych/test_yamlstore.rb b/test/psych/test_yamlstore.rb
index 1cd3ec4..1a1be37 100644
--- a/test/psych/test_yamlstore.rb
+++ b/test/psych/test_yamlstore.rb
@@ -4,7 +4,22 @@ require 'yaml/store'
 require 'tmpdir'
 
 module Psych
-  Psych::Store = YAML::Store unless defined?(Psych::Store)
+  class YAML::Store
+    alias :old_load :load
+
+    def load(content)
+      table = YAML.load(content, fallback: false)
+      if table == false
+        {}
+      else
+        table
+      end
+    end
+  end
+
+  unless defined?(Psych::Store)
+    Psych::Store = YAML::Store
+  end
 
   class YAMLStoreTest < TestCase
     def setup
@@ -24,61 +39,61 @@ module Psych
 
     def test_opening_new_file_in_readonly_mode_should_result_in_empty_values
       @yamlstore.transaction(true) do
-        assert_nil @yamlstore[:foo]
-        assert_nil @yamlstore[:bar]
+        assert_nil @yamlstore["foo"]
+        assert_nil @yamlstore["bar"]
       end
     end
 
     def test_opening_new_file_in_readwrite_mode_should_result_in_empty_values
       @yamlstore.transaction do
-        assert_nil @yamlstore[:foo]
-        assert_nil @yamlstore[:bar]
+        assert_nil @yamlstore["foo"]
+        assert_nil @yamlstore["bar"]
       end
     end
 
     def test_data_should_be_loaded_correctly_when_in_readonly_mode
       @yamlstore.transaction do
-        @yamlstore[:foo] = "bar"
+        @yamlstore["foo"] = "bar"
       end
       @yamlstore.transaction(true) do
-        assert_equal "bar", @yamlstore[:foo]
+        assert_equal "bar", @yamlstore["foo"]
       end
     end
 
     def test_data_should_be_loaded_correctly_when_in_readwrite_mode
       @yamlstore.transaction do
-        @yamlstore[:foo] = "bar"
+        @yamlstore["foo"] = "bar"
       end
       @yamlstore.transaction do
-        assert_equal "bar", @yamlstore[:foo]
+        assert_equal "bar", @yamlstore["foo"]
       end
     end
 
     def test_changes_after_commit_are_discarded
       @yamlstore.transaction do
-        @yamlstore[:foo] = "bar"
+        @yamlstore["foo"] = "bar"
         @yamlstore.commit
-        @yamlstore[:foo] = "baz"
+        @yamlstore["foo"] = "baz"
       end
       @yamlstore.transaction(true) do
-        assert_equal "bar", @yamlstore[:foo]
+        assert_equal "bar", @yamlstore["foo"]
       end
     end
 
     def test_changes_are_not_written_on_abort
       @yamlstore.transaction do
-        @yamlstore[:foo] = "bar"
+        @yamlstore["foo"] = "bar"
         @yamlstore.abort
       end
       @yamlstore.transaction(true) do
-        assert_nil @yamlstore[:foo]
+        assert_nil @yamlstore["foo"]
       end
     end
 
     def test_writing_inside_readonly_transaction_raises_error
       assert_raise(PStore::Error) do
         @yamlstore.transaction(true) do
-          @yamlstore[:foo] = "bar"
+          @yamlstore["foo"] = "bar"
         end
       end
     end