process.c: defaults to close_others false

Arbitrarily closing file descriptors on exec breaks use cases
where a Ruby process sets up a descriptor for non-Ruby children
to use.  For example, the "rake foo" target may spawn any number
of subprocesses (Ruby or not) which depends on parsing the "FOO"
environment variable for out_fd:99 and writing to foo.out

    FOO=out_fd:99 rake foo 99>>foo.out

Unfortunately, this introduced one incompatibility in
test/lib/test/unit.rb and it now requires explicitly setting
IO#close_on_exec=true

[ruby-core:88007] [Misc #14907]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64399 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

process.c

@@ -3496,7 +3496,7 @@ rb_execarg_run_options(const struct rb_execarg *eargp, struct rb_execarg *sargp,
     }
 
 #ifdef HAVE_WORKING_FORK
-    if (!eargp->close_others_given || eargp->close_others_do) {
+    if (eargp->close_others_do) {
         rb_close_before_exec(3, eargp->close_others_maxhint, eargp->redirect_fds); /* async-signal-safe */
     }
 #endif
@@ -4568,7 +4568,7 @@ rb_f_system(int argc, VALUE *argv)
  *          integer : the file descriptor of specified the integer
  *          io      : the file descriptor specified as io.fileno
  *      file descriptor inheritance: close non-redirected non-standard fds (3, 4, 5, ...) or not
- *        :close_others => true  : don't inherit
+ *        :close_others => false  : inherit
  *      current directory:
  *        :chdir => str
  *
@@ -4727,7 +4727,7 @@ rb_f_system(int argc, VALUE *argv)
  *    pid = spawn(command, :close_others=>true)  # close 3,4,5,... (default)
  *    pid = spawn(command, :close_others=>false) # don't close 3,4,5,...
  *
- *  :close_others is true by default for spawn and IO.popen.
+ *  :close_others is false by default for spawn and IO.popen.
  *
  *  Note that fds which close-on-exec flag is already set are closed
  *  regardless of :close_others option.

test/lib/test/unit.rb

@@ -145,6 +145,8 @@ module Test
             r.close if r
             nil
           else
+            r.close_on_exec = true
+            w.close_on_exec = true
             @jobserver = [r, w]
             options[:parallel] ||= 1
           end

test/ruby/test_process.rb

@@ -1009,6 +1009,15 @@ class TestProcess < Test::Unit::TestCase
     }
   end
 
+  def test_close_others_default_false
+    IO.pipe do |r,w|
+      w.close_on_exec = false
+      src = "IO.new(#{w.fileno}).puts(:hi)"
+      assert_equal true, system(*%W(#{RUBY} --disable=gems -e #{src}))
+      assert_equal "hi\n", r.gets
+    end
+  end
+
   def test_execopts_redirect_self
     begin
       with_pipe {|r, w|