mame	2017-09-11 21:44:51 +0900 (Mon, 11 Sep 2017)

  New Revision: 59840

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=59840

  Log:
    lib/securerandom.rb: test one byte to determine urandom or openssl
    
    `SecureRandom#gen_random` determines whether urandom is available or not
    by trying `Random.urandom(n)`.  But, when n = 0, `Random.urandom(0)`
    always succeeds even if urandom is not available, which leads to a wrong
    decision.
    
    When failed, `Random.urandom` returns nil instead of returning a shorter
    string than required.  So the check for `ret.length != n` is not needed.

  Modified files:
    trunk/lib/securerandom.rb
Index: lib/securerandom.rb
===================================================================
--- lib/securerandom.rb	(revision 59839)
+++ lib/securerandom.rb	(revision 59840)
@@ -52,7 +52,7 @@ module SecureRandom https://github.com/ruby/ruby/blob/trunk/lib/securerandom.rb#L52
     end
 
     def gen_random(n)
-      ret = Random.urandom(n)
+      ret = Random.urandom(1)
       if ret.nil?
         begin
           require 'openssl'
@@ -67,10 +67,6 @@ module SecureRandom https://github.com/ruby/ruby/blob/trunk/lib/securerandom.rb#L67
           end
           return gen_random(n)
         end
-      elsif ret.length != n
-        raise NotImplementedError, \
-              "Unexpected partial read from random device: " \
-              "only #{ret.length} for #{n} bytes"
       else
         @rng_chooser.synchronize do
           class << self

--
ML: ruby-changes@q...
Info: http://www.atdot.net/~ko1/quickml/