Allow options on Mash.load (#474)

`Mash.load` uses the Ruby standard library to load Yaml-serialized files
into a Mash. The original implementation used `YAML.load` for this
purpose. However, that method is inherently unsafe so we switched to
using `YAML.safe_load`.

Safely loading Yaml files has many different domain-specific
configuration flags that we did not, by default, expose. This change
introduces the ability to configure the safe loading of Yaml files so
that all types of Yaml can be loaded when necessary using the flags from
the standard library.

This implementation preserves the backwards-compatibility with the prior
implementation so that it should not require updates from users of the
current `Mash.load` behavior. For those who this change affects, we
included upgrading documentation to ease the transition.

9 files changed, 102 insertions, 15 deletions

diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index 944b8dc..4f87d3b 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -1,6 +1,6 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2018-09-30 14:46:03 -0500 using RuboCop version 0.52.1.
+# on 2019-03-22 11:21:24 -0400 using RuboCop version 0.52.1.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
@@ -19,7 +19,7 @@ Metrics/ClassLength:
 Metrics/CyclomaticComplexity:
   Max: 11
 
-# Offense count: 17
+# Offense count: 19
 # Configuration parameters: CountComments.
 Metrics/MethodLength:
   Max: 28
@@ -28,6 +28,6 @@ Metrics/MethodLength:
 Metrics/PerceivedComplexity:
   Max: 10
 
-# Offense count: 37
+# Offense count: 39
 Style/Documentation:
   Enabled: false
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2d123ff..caf8080 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@ scheme are considered to be bugs.
 ### Added
 
 * [#323](https://github.com/intridea/hashie/pull/323): Added `Hashie::Extensions::Mash::DefineAccessors` - [@marshall-lee](https://github.com/marshall-lee).
+* [#474](https://github.com/intridea/hashie/pull/474): Expose `YAML#safe_load` options in `Mash#load` - [@riouruma](https://github.com/riouruma), [@dblock](https://github.com/dblock).
 
 ### Changed
 
diff --git a/README.md b/README.md
index 77456ac..c31a632 100644
--- a/README.md
+++ b/README.md
@@ -566,7 +566,7 @@ Twitter.extend mash.to_module # NOTE: if you want another name than settings, ca
 Twitter.settings.api_key # => 'abcd'
 ```
 
-You can use another parser (by default: YamlErbParser):
+You can use another parser (by default: [YamlErbParser](lib/hashie/extensions/parsers/yaml_erb_parser.rb)):
 
 ```
 #/etc/data/user.csv
@@ -582,6 +582,14 @@ mash = Mash.load('data/user.csv', parser: MyCustomCsvParser)
 mash[1] #=> { name: 'John', lastname: 'Doe' }
 ```
 
+The `Mash#load` method calls `YAML.safe_load(path, [], [], true)`.
+
+Specify `whitelist_symbols`, `whitelist_classes` and `aliases` options as needed.
+
+```ruby
+Mash.load('data/user.csv', whitelist_classes: [Symbol], whitelist_symbols: [], aliases: false)
+```
+
 ### Mash Extension: KeepOriginalKeys
 
 This extension can be mixed into a Mash to keep the form of any keys passed directly into the Mash. By default, Mash converts keys to strings to give indifferent access. This extension still allows indifferent access, but keeps the form of the keys to eliminate confusion when you're not expecting the keys to change.
diff --git a/UPGRADING.md b/UPGRADING.md
index 5a9f05a..6c8ac93 100644
--- a/UPGRADING.md
+++ b/UPGRADING.md
@@ -1,6 +1,41 @@
 Upgrading Hashie
 ================
 
+### Upgrading to 3.7.0
+
+#### Mash#load takes options
+
+The `Hashie::Mash#load` method now accepts options, changing the interface of `Parser#initialize`. If you have a custom parser, you must update its `initialize` method.
+
+For example, `Hashie::Extensions::Parsers::YamlErbParser` now accepts `whitelist_classes`, `whitelist_symbols` and `aliases` options.
+
+Before:
+
+```ruby
+class Hashie::Extensions::Parsers::YamlErbParser
+  def initialize(file_path)
+    @file_path = file_path
+  end
+end
+```
+
+After:
+
+```ruby
+class Hashie::Extensions::Parsers::YamlErbParser
+  def initialize(file_path, options = {})
+    @file_path = file_path
+    @options = options
+  end
+end
+```
+
+Options can now be passed into `Mash#load`.
+
+```ruby
+Mash.load(filename, whitelist_classes: [])
+```
+
 ### Upgrading to 3.5.2
 
 #### Disable logging in Mash subclasses
diff --git a/lib/hashie/extensions/parsers/yaml_erb_parser.rb b/lib/hashie/extensions/parsers/yaml_erb_parser.rb
index d3b5c80..05edc40 100644
--- a/lib/hashie/extensions/parsers/yaml_erb_parser.rb
+++ b/lib/hashie/extensions/parsers/yaml_erb_parser.rb
@@ -6,19 +6,23 @@ module Hashie
   module Extensions
     module Parsers
       class YamlErbParser
-        def initialize(file_path)
+        def initialize(file_path, options = {})
           @content = File.read(file_path)
           @file_path = file_path.is_a?(Pathname) ? file_path.to_s : file_path
+          @options = options
         end
 
         def perform
           template = ERB.new(@content)
           template.filename = @file_path
-          YAML.safe_load template.result, [], [], true
+          whitelist_classes = @options.fetch(:whitelist_classes) { [] }
+          whitelist_symbols = @options.fetch(:whitelist_symbols) { [] }
+          aliases = @options.fetch(:aliases) { true }
+          YAML.safe_load template.result, whitelist_classes, whitelist_symbols, aliases
         end
 
-        def self.perform(file_path)
-          new(file_path).perform
+        def self.perform(file_path, options = {})
+          new(file_path, options).perform
         end
       end
     end
diff --git a/lib/hashie/mash.rb b/lib/hashie/mash.rb
index f41d745..650a269 100644
--- a/lib/hashie/mash.rb
+++ b/lib/hashie/mash.rb
@@ -107,7 +107,7 @@ module Hashie
       raise ArgumentError, "The following file doesn't exist: #{path}" unless File.file?(path)
 
       parser = options.fetch(:parser) { Hashie::Extensions::Parsers::YamlErbParser }
-      @_mashes[path] = new(parser.perform(path)).freeze
+      @_mashes[path] = new(parser.perform(path, options.except(:parser))).freeze
     end
 
     def to_module(mash_method_name = :settings)
diff --git a/lib/hashie/version.rb b/lib/hashie/version.rb
index 1206e92..22480fb 100644
--- a/lib/hashie/version.rb
+++ b/lib/hashie/version.rb
@@ -1,3 +1,3 @@
 module Hashie
-  VERSION = '3.6.1'.freeze
+  VERSION = '3.7.0'.freeze
 end
diff --git a/spec/fixtures/yaml_with_symbols.yml b/spec/fixtures/yaml_with_symbols.yml
new file mode 100644
index 0000000..c761e2b
--- /dev/null
+++ b/spec/fixtures/yaml_with_symbols.yml
@@ -0,0 +1,3 @@
+:user_icon:
+  :width: 200
+  :height: 200
diff --git a/spec/hashie/mash_spec.rb b/spec/hashie/mash_spec.rb
index be82281..59e3183 100644
--- a/spec/hashie/mash_spec.rb
+++ b/spec/hashie/mash_spec.rb
@@ -645,7 +645,7 @@ describe Hashie::Mash do
     context 'if the file exists' do
       before do
         expect(File).to receive(:file?).with(path).and_return(true)
-        expect(parser).to receive(:perform).with(path).and_return(config)
+        expect(parser).to receive(:perform).with(path, {}).and_return(config)
       end
 
       it { is_expected.to be_a(Hashie::Mash) }
@@ -677,7 +677,7 @@ describe Hashie::Mash do
 
       before do
         expect(File).to receive(:file?).with(path).and_return(true)
-        expect(parser).to receive(:perform).with(path).and_return(config)
+        expect(parser).to receive(:perform).with(path, {}).and_return(config)
       end
 
       it 'return a Mash from a file' do
@@ -693,8 +693,8 @@ describe Hashie::Mash do
       before do
         expect(File).to receive(:file?).with(path).and_return(true)
         expect(File).to receive(:file?).with("#{path}+1").and_return(true)
-        expect(parser).to receive(:perform).once.with(path).and_return(config)
-        expect(parser).to receive(:perform).once.with("#{path}+1").and_return(config)
+        expect(parser).to receive(:perform).once.with(path, {}).and_return(config)
+        expect(parser).to receive(:perform).once.with("#{path}+1", {}).and_return(config)
       end
 
       it 'cache the loaded yml file', :test_cache do
@@ -710,9 +710,45 @@ describe Hashie::Mash do
     context 'when the file has aliases in it' do
       it 'can use the aliases and does not raise an error' do
         mash = Hashie::Mash.load('spec/fixtures/yaml_with_aliases.yml')
-
         expect(mash.company_a.accounts.admin.password).to eq('secret')
       end
+      it 'can override the value of aliases' do
+        expect do
+          Hashie::Mash.load('spec/fixtures/yaml_with_aliases.yml', aliases: false)
+        end.to raise_error Psych::BadAlias, /base_accounts/
+      end
+    end
+
+    context 'when the file has symbols' do
+      it 'can override the value of whitelist_classes' do
+        mash = Hashie::Mash.load('spec/fixtures/yaml_with_symbols.yml', whitelist_classes: [Symbol])
+        expect(mash.user_icon.width).to eq(200)
+      end
+      it 'uses defaults for whitelist_classes' do
+        expect do
+          Hashie::Mash.load('spec/fixtures/yaml_with_symbols.yml')
+        end.to raise_error Psych::DisallowedClass, /Symbol/
+      end
+      it 'can override the value of whitelist_symbols' do
+        mash = Hashie::Mash.load('spec/fixtures/yaml_with_symbols.yml',
+                                 whitelist_classes: [Symbol],
+                                 whitelist_symbols: %i[
+                                   user_icon
+                                   width
+                                   height
+                                 ])
+        expect(mash.user_icon.width).to eq(200)
+      end
+      it 'raises an error on insufficient whitelist_symbols' do
+        expect do
+          Hashie::Mash.load('spec/fixtures/yaml_with_symbols.yml',
+                            whitelist_classes: [Symbol],
+                            whitelist_symbols: %i[
+                              user_icon
+                              width
+                            ])
+        end.to raise_error Psych::DisallowedClass, /Symbol/
+      end
     end
   end