* lib/open3.rb: double fork is replaced by spawn with Process.detach.

  (Open3.popen3w): new method to access the thread returned by
  Process.detach.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@16198 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 48 insertions, 29 deletions

diff --git a/lib/open3.rb b/lib/open3.rb
index c4dacc9473..3824c81378 100644
--- a/lib/open3.rb
+++ b/lib/open3.rb
@@ -17,6 +17,8 @@
 #   
 #   stdin, stdout, stderr = popen3('nroff -man')
 #
+# If the exit status of the child process is required, Open3.popen3w is usable.
+#
 # Open3.popen3 can also take a block which will receive stdin, stdout and
 # stderr as parameters.  This ensures stdin, stdout and stderr are closed
 # once the block exits. Example:
@@ -29,62 +31,79 @@
 module Open3
   # 
   # Open stdin, stdout, and stderr streams and start external executable.
+  #
   # Non-block form:
   #   
-  #   require 'open3'
-  #
-  #   [stdin, stdout, stderr] = Open3.popen3(cmd)
+  #   stdin, stdout, stderr = Open3.popen3(cmd)
+  #   ...
+  #   stdin.close  # stdin, stdout and stderr should be closed in this form.
+  #   stdout.close
+  #   stderr.close
   #
   # Block form:
   #
   #   require 'open3'
   #
   #   Open3.popen3(cmd) { |stdin, stdout, stderr| ... }
+  #   # stdin, stdout and stderr is closed automatically in this form.
   #
-  # The parameter +cmd+ is passed directly to Kernel#exec.
+  # The parameter +cmd+ is passed directly to Kernel#spawn.
   #
   def popen3(*cmd)
+    if defined? yield
+      popen3w(*cmd) {|stdin, stdout, stderr, wait_thr|
+        yield stdin, stdout, stderr
+      }
+    else
+      stdin, stdout, stderr, wait_thr = popen3w(*cmd)
+      return stdin, stdout, stderr
+    end
+  end
+  module_function :popen3
+
+  # 
+  # Open stdin, stdout, and stderr streams and start external executable.
+  # In addition, a thread for waiting the started process is noticed.
+  #
+  # Non-block form:
+  #   
+  #   stdin, stdout, stderr, wait_thr = Open3.popen3w(cmd)
+  #   ...
+  #   stdin.close  # stdin, stdout and stderr should be closed in this form.
+  #   stdout.close
+  #   stderr.close
+  #   exit_status = wait_thr.value  # Process::Status object returned.
+  #
+  # Block form:
+  #
+  #   Open3.popen3w(cmd) { |stdin, stdout, stderr, wait_thr| ... }
+  #
+  # The parameter +cmd+ is passed directly to Kernel#spawn.
+  #
+  def popen3w(*cmd)
     pw = IO::pipe   # pipe[0] for read, pipe[1] for write
     pr = IO::pipe
     pe = IO::pipe
 
-    pid = fork{
-      # child
-      fork{
-	# grandchild
-	pw[1].close
-	STDIN.reopen(pw[0])
-	pw[0].close
-
-	pr[0].close
-	STDOUT.reopen(pr[1])
-	pr[1].close
-
-	pe[0].close
-	STDERR.reopen(pe[1])
-	pe[1].close
-
-	exec(*cmd)
-      }
-      exit!(0)
-    }
-
+    pid = spawn(*cmd, STDIN=>pw[0], STDOUT=>pr[1], STDERR=>pe[1])
+    wait_thr = Process.detach(pid)
+    wait_thr[:pid] = pid
     pw[0].close
     pr[1].close
     pe[1].close
-    Process.waitpid(pid)
-    pi = [pw[1], pr[0], pe[0]]
+    pi = [pw[1], pr[0], pe[0], wait_thr]
     pw[1].sync = true
     if defined? yield
       begin
 	return yield(*pi)
       ensure
-	pi.each{|p| p.close unless p.closed?}
+	[pw[1], pr[0], pe[0]].each{|p| p.close unless p.closed?}
+        wait_thr.join
       end
     end
     pi
   end
-  module_function :popen3
+  module_function :popen3w
 end
 
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