Add length option

Author: nobu

lib/cgi/session.rb

@@ -206,13 +206,15 @@ def create_new_id
     #          on Unix systems).
     # prefix:: the prefix to add to the session id when generating
     #          the filename for this session's FileStore file.
-    #          Defaults to "cgi_sid_".
+    #          Defaults to the empty string.
     # suffix:: the prefix to add to the session id when generating
     #          the filename for this session's FileStore file.
     #          Defaults to the empty string.
     # digest:: the digest algorithm to hash the session id when
     #          generating the filename for this session's FileStore
     #          file.  Defaults to "SHA256".
+    # length:: the length of the session id part of the filestore,
+    #          excluding +prefix+ and +suffix+ parts.  Defaults to 16.
     def new_store_file(option={}) # :nodoc:
       dir = option['tmpdir'] || Dir::tmpdir
       prefix = option['prefix']
@@ -222,7 +224,7 @@ def new_store_file(option={}) # :nodoc:
         require 'digest'
         algorithm = Digest(algorithm)
       end
-      digest = algorithm.hexdigest(session_id)[0,16]
+      digest = algorithm.hexdigest(session_id)[0, option['length'] || 16]
       path = dir+"/"
       path << prefix if prefix
       path << digest

test/cgi/test_cgi_session.rb

@@ -177,6 +177,9 @@ def test_cgi_session_filestore_path
     path_sha512 = session_file_store_path("tmpdir"=>@session_dir, "session_id"=>session_id, "digest"=>"SHA512")
     assert_session_filestore_path(path_default)
     assert_not_equal path_sha512, path_default
+    path_long = session_file_store_path("tmpdir"=>@session_dir, "session_id"=>session_id, "length"=>32)
+    assert_equal path_default.length+16, path_long.length
+    assert_send [path_long, :start_with?, path_default]
 
     path = session_file_store_path("tmpdir"=>@session_dir, "session_id"=>session_id, "digest"=>Digest::SHA256)
     assert_equal path_default, path