Fixed problem escaping string in JSON

Signed-off-by: sanga17 <sausekar@msystechnologies.com>

lib/chef-vault/exceptions.rb

@@ -51,5 +51,8 @@ class IdMismatch < Exceptions
 
     class V1Format < Exceptions
     end
+
+    class InvalidValue < Exceptions
+    end
   end
 end

lib/chef/knife/mixin/helper.rb

@@ -27,6 +27,7 @@ def set_mode(mode)
       def merge_values(json, file)
         values = {}
         values.merge!(values_from_file(file)) if file
+        validate_json(json)
         values.merge!(values_from_json(json)) if json
 
         values
@@ -43,6 +44,35 @@ def values_from_json(json)
       rescue JSON::ParserError
         raise JSON::ParserError, "#{json} is not valid JSON!"
       end
+
+      # I/P: json string
+      # It checks wheather it contains any non-printable character present or not,
+      # If present then raises error of InvalidValue
+      def validate_json(json)
+        begin
+          evaled_json = eval(json)
+        rescue StandardError => e
+          puts e.message
+        end
+
+        if evaled_json.is_a?(Hash)
+          evaled_json.each do |key, value|
+            next if printable?(value)
+
+            msg = "Value '#{value}' of key '#{key}' contains non-printable characters. Check that backslashes are escaped with another backslash (e.g. C:\\\\Windows) in double-quoted strings."
+            raise ChefVault::Exceptions::InvalidValue, msg
+          end
+        end
+      end
+
+      # I/P: String
+      # O/P: true/false
+      # returns true if string is free of non-printable characters (escape sequences)
+      # this returns false for whitespace escape sequences as well, e.g. \n\t
+      def printable?(string)
+        return false if string =~ /[^[:print:]]/
+        true
+      end
     end
   end
 end