From: Laurent Sansonetti <laurent@...>
Date: 2003-05-16T05:55:13+09:00
Subject: PTY: still problems (+patch)

Hi all,

I just built the lastest ruby distribution from CVS, and noticed that
PTY.spawn() does not throw a PTY::ChildExit exception after the process
death.

I'm running FreeBSD -current.

After some pty.c debug, I noticed that pty_finalize_syswait() was
called *before* pty_syswait(), thus the thread was killed before it
could call rb_waitpid().

Here is a short program I used to remark this problem::

<<----------------------------------------------------------------------
require './pty.so'
def myexec(cmd)
    begin
        PTY.spawn(cmd) do |r, w, pid|
            r.each { |line| puts "-> #{line}" }
            # sleep 1
        end
    rescue PTY::ChildExited => e
        puts "STATUS: #{e.status}"
    end
end
myexec("uname")
myexec("ls /does_not_exist")
myexec("pleplrpaezlra")
-------------------------------------------------------------------->>

It produces the following output:

	-> FreeBSD
	-> ls: /does_not_exist: No such file or directory

Note that if you uncomment the ``sleep 1'' line, PTY.spawn will raise a
ChildExited object, which is the expected behaviour:

	-> FreeBSD	
	STATUS: 0
	-> ls: /does_not_exist: No such file or directory
	STATUS: 256
	STATUS: 256

The following patch fixes this issue, by 'joining' the thread instead of killing it:

pinux@natalie ~/ruby/ext/pty> cvs diff -u pty.c
Index: pty.c
===================================================================
RCS file: /src/ruby/ext/pty/pty.c,v
retrieving revision 1.15
diff -u -r1.15 pty.c
--- pty.c       10 Mar 2003 15:05:18 -0000      1.15
+++ pty.c       15 May 2003 20:24:38 -0000
@@ -299,7 +299,7 @@
 pty_finalize_syswait(info)
     struct pty_info *info;
 {
-    rb_thread_kill(info->thread);
+    rb_funcall(info->thread, rb_intern("join"), 0);
     rb_detach_process(info->child_pid);
     return Qnil;
 }

BTW, I saw that rb_thread_join() is private.  Perhaps it should be
exported, in order to use its 'limit' parameter here.  

-- 
Laurent