Remove UTF-8 BOM from config files before parsing

lib/sensu/settings/loader.rb

@@ -86,7 +86,7 @@ def load_file(file)
         if File.file?(file) && File.readable?(file)
           begin
             warning("loading config file", :file => file)
-            contents = IO.read(file)
+            contents = read_config_file(file)
             config = MultiJson.load(contents, :symbolize_keys => true)
             merged = deep_merge(@settings, config)
             unless @loaded_files.empty?
@@ -190,10 +190,32 @@ def indifferent_access!
         @indifferent_access = true
       end
 
+      # Read a configuration file and force its encoding to 8-bit
+      # ASCII, ignoring invalid characters. If there is a UTF-8 BOM,
+      # it will be removed. Some JSON parsers force ASCII but do not
+      # remove the UTF-8 BOM if present, causing encoding conversion
+      # errors. This method is for consistency across MultiJson
+      # adapters and system platforms.
+      #
+      # @param [String] file path to read.
+      # @return [String] file contents.
+      def read_config_file(file)
+        contents = IO.read(file)
+        if contents.respond_to?(:force_encoding)
+          encoding = ::Encoding::ASCII_8BIT
+          contents = contents.force_encoding(encoding)
+          contents.sub!("\xEF\xBB\xBF".force_encoding(encoding), "")
+        else
+          contents.sub!(/^\357\273\277/, "")
+        end
+        contents
+      end
+
       # Deep merge two hashes.
       #
       # @param [Hash] hash_one to serve as base.
       # @param [Hash] hash_two to merge in.
+      # @return [Hash] deep merged hash.
       def deep_merge(hash_one, hash_two)
         merged = hash_one.dup
         hash_two.each do |key, value|

spec/assets/bom.json

@@ -0,0 +1,7 @@
+{
+	"client": {
+		"name": "bom",
+		"address": "utf-8",
+		"subscriptions": ["encoding"]
+	}
+}

spec/loader_spec.rb

@@ -97,6 +97,14 @@
     expect(messages).to include("ignoring config file")
   end
 
+  it "can load settings from a utf-8 encoded file with a bom" do
+    @loader.load_file(File.join(@assets_dir, "bom.json"))
+    warnings = @loader.warnings
+    failures = @loader.validate
+    expect(warnings.size).to eq(1)
+    expect(failures.size).to eq(0)
+  end
+
   it "can load settings from files in a directory" do
     @loader.load_directory(@config_dir)
     warnings = @loader.warnings