1 files changed, 15 insertions, 11 deletions
diff --git a/lib/rubygems/specification_policy.rb b/lib/rubygems/specification_policy.rb
index d117120e9a..e28408a5a5 100644
--- a/lib/rubygems/specification_policy.rb
+++ b/lib/rubygems/specification_policy.rb
@@ -4,6 +4,8 @@ require 'uri'
 class Gem::SpecificationPolicy < SimpleDelegator
   VALID_NAME_PATTERN = /\A[a-zA-Z0-9\.\-\_]+\z/ # :nodoc:
 
+  SPECIAL_CHARACTERS = /\A[#{Regexp.escape('.-_')}]+/ # :nodoc:
+
   VALID_URI_PATTERN = %r{\Ahttps?:\/\/([^\s:@]+:[^\s:@]*@)?[A-Za-z\d\-]+(\.[A-Za-z\d\-]+)+\.?(:\d{1,5})?([\/?]\S*)?\z}  # :nodoc:
 
   METADATA_LINK_KEYS = %w[
@@ -14,7 +16,7 @@ class Gem::SpecificationPolicy < SimpleDelegator
     mailing_list_uri
     source_code_uri
     wiki_uri
-  ] # :nodoc:
+  ].freeze # :nodoc:
 
   def initialize(specification)
     @warnings = 0
@@ -219,12 +221,14 @@ open-ended dependency on #{dep} is not recommended
   end
 
   def validate_name
-    if !name.is_a?(String) then
+    if !name.is_a?(String)
       error "invalid value for attribute name: \"#{name.inspect}\" must be a string"
-    elsif name !~ /[a-zA-Z]/ then
+    elsif name !~ /[a-zA-Z]/
       error "invalid value for attribute name: #{name.dump} must include at least one letter"
-    elsif name !~ VALID_NAME_PATTERN then
+    elsif name !~ VALID_NAME_PATTERN
       error "invalid value for attribute name: #{name.dump} can only include letters, numbers, dashes, and underscores"
+    elsif name =~ SPECIAL_CHARACTERS
+      error "invalid value for attribute name: #{name.dump} can not begin with a period, dash, or underscore"
     end
   end
 
@@ -257,9 +261,9 @@ open-ended dependency on #{dep} is not recommended
 
   def validate_platform
     case platform
-      when Gem::Platform, Gem::Platform::RUBY then # ok
-      else
-        error "invalid platform #{platform.inspect}, see Gem::Platform"
+    when Gem::Platform, Gem::Platform::RUBY then # ok
+    else
+      error "invalid platform #{platform.inspect}, see Gem::Platform"
     end
   end
 
@@ -272,10 +276,10 @@ open-ended dependency on #{dep} is not recommended
   def validate_array_attribute(field)
     val = self.send(field)
     klass = case field
-              when :dependencies then
-                Gem::Dependency
-              else
-                String
+            when :dependencies then
+              Gem::Dependency
+            else
+              String
             end
 
     unless Array === val and val.all? {|x| x.kind_of?(klass)} then