popen: shell commands with envvars and execopts

* io.c (is_popen_fork): check if fork and raise NotImplementedError if
  unavailable.
* io.c (rb_io_s_popen): allow environment variables hash and exec
  options as flat parameters, not in an array arguments.
  [Feature#6651] [EXPERIMENTAL]
* process.c (rb_execarg_extract_options): extract exec options, but no
  exceptions on non-exec options and returns them as a Hash.
* process.c (rb_execarg_setenv): set environment variables.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@36229 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/ruby/test_process.rb

@@ -303,6 +303,47 @@ class TestProcess < Test::Unit::TestCase
     end
   end
 
+  def _test_execopts_env_popen(cmd)
+    message = cmd.inspect
+    IO.popen({"FOO"=>"BAR"}, cmd) {|io|
+      assert_equal('FOO=BAR', io.read[/^FOO=.*/], message)
+    }
+
+    old = ENV["hmm"]
+    begin
+      ENV["hmm"] = "fufu"
+      IO.popen(cmd) {|io| assert_match(/^hmm=fufu$/, io.read, message)}
+      IO.popen({"hmm"=>""}, cmd) {|io| assert_match(/^hmm=$/, io.read, message)}
+      IO.popen({"hmm"=>nil}, cmd) {|io| assert_not_match(/^hmm=/, io.read, message)}
+      ENV["hmm"] = ""
+      IO.popen(cmd) {|io| assert_match(/^hmm=$/, io.read, message)}
+      IO.popen({"hmm"=>""}, cmd) {|io| assert_match(/^hmm=$/, io.read, message)}
+      IO.popen({"hmm"=>nil}, cmd) {|io| assert_not_match(/^hmm=/, io.read, message)}
+      ENV["hmm"] = nil
+      IO.popen(cmd) {|io| assert_not_match(/^hmm=/, io.read, message)}
+      IO.popen({"hmm"=>""}, cmd) {|io| assert_match(/^hmm=$/, io.read, message)}
+      IO.popen({"hmm"=>nil}, cmd) {|io| assert_not_match(/^hmm=/, io.read, message)}
+    ensure
+      ENV["hmm"] = old
+    end
+  end
+
+  def test_execopts_env_popen_vector
+    _test_execopts_env_popen(ENVCOMMAND)
+  end
+
+  def test_execopts_env_popen_string
+    with_tmpchdir do |d|
+      open('test-script', 'w') do |f|
+        ENVCOMMAND.each_with_index do |cmd, i|
+          next if i.zero? or cmd == "-e"
+          f.puts cmd
+        end
+      end
+      _test_execopts_env_popen("#{RUBY} test-script")
+    end
+  end
+
   def test_execopts_preserve_env_on_exec_failure
     with_tmpchdir {|d|
       write_file 's', <<-"End"