1 files changed, 26 insertions, 9 deletions
diff --git a/lib/rdoc/parser.rb b/lib/rdoc/parser.rb
index 506b5e7d1b..47ecd746d0 100644
--- a/lib/rdoc/parser.rb
+++ b/lib/rdoc/parser.rb
@@ -58,7 +58,7 @@ class RDoc::Parser
     old_ext = old_ext.sub(/^\.(.*)/, '\1')
     new_ext = new_ext.sub(/^\.(.*)/, '\1')
 
-    parser = can_parse "xxx.#{old_ext}"
+    parser = can_parse_by_name "xxx.#{old_ext}"
     return false unless parser
 
     RDoc::Parser.parsers.unshift [/\.#{new_ext}$/, parser]
@@ -77,14 +77,14 @@ class RDoc::Parser
 
     have_encoding = s.respond_to? :encoding
 
-    if have_encoding then
-      return false if s.encoding != Encoding::ASCII_8BIT and s.valid_encoding?
-    end
-
     return true if s[0, 2] == Marshal.dump('')[0, 2] or s.index("\x00")
 
     if have_encoding then
-      s.force_encoding Encoding.default_external
+      mode = "r"
+      s.sub!(/\A#!.*\n/, '')     # assume shebang line isn't longer than 1024.
+      encoding = s[/^\s*\#\s*(?:-\*-\s*)?(?:en)?coding:\s*([^\s;]+?)(?:-\*-|[\s;])/, 1]
+      mode = "r:#{encoding}" if encoding
+      s = File.open(file, mode) {|f| f.gets(nil, 1024)}
 
       not s.valid_encoding?
     else
@@ -131,23 +131,36 @@ class RDoc::Parser
     zip_signature == "PK\x03\x04" or
       zip_signature == "PK\x05\x06" or
       zip_signature == "PK\x07\x08"
+  rescue
+    false
   end
 
   ##
   # Return a parser that can handle a particular extension
 
-  def self.can_parse(file_name)
-    parser = RDoc::Parser.parsers.find { |regexp,| regexp =~ file_name }.last
+  def self.can_parse file_name
+    parser = can_parse_by_name file_name
 
     # HACK Selenium hides a jar file using a .txt extension
     return if parser == RDoc::Parser::Simple and zip? file_name
 
+    parser
+  end
+
+  ##
+  # Returns a parser that can handle the extension for +file_name+.  This does
+  # not depend upon the file being readable.
+
+  def self.can_parse_by_name file_name
+    _, parser = RDoc::Parser.parsers.find { |regexp,| regexp =~ file_name }
+
     # The default parser must not parse binary files
     ext_name = File.extname file_name
     return parser if ext_name.empty?
+
     if parser == RDoc::Parser::Simple and ext_name !~ /txt|rdoc/ then
       case check_modeline file_name
-      when 'rdoc' then # continue
+      when nil, 'rdoc' then # continue
       else return nil
       end
     end
@@ -173,6 +186,8 @@ class RDoc::Parser
       type = $1
     end
 
+    return nil if /coding:/i =~ type
+
     type.downcase
   rescue ArgumentError # invalid byte sequence, etc.
   end
@@ -204,6 +219,8 @@ class RDoc::Parser
     return unless parser
 
     parser.new top_level, file_name, content, options, stats
+  rescue SystemCallError
+    nil
   end
 
   ##