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Date: Wed, 22 May 2002 12:59:21 -0400
From: Christopher Faylor <cgf-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: Bug: fhandler.cc rev=1.116 source code level bug in fhandler_base::dup (fhandler_base *child)
Message-ID: <20020522165921.GB3592@redhat.com>
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References: <001101c201a8$2148fc40$df250b93 AT ALASTIMSON>
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On Wed, May 22, 2002 at 08:48:33AM -0700, Leo Kuznetsov wrote:
>Hi,
>
>I might be wrong but it looks like:
>
>In the function below
>------------------------
>  if (get_nohandle ())
>    nh = NULL;        // NULL == 0 and is a valid (but possibly closed) handle
>
>------------------------
>MUST BE
>------------------------
>  if (get_nohandle ())
>    nh = (HANDLE)-1;  // or better yet INVALID_HANDLE_VALUE
>
>=========================
>Otherwise dup(dup(-1)) == dup(0) and
>sets an error if handle 0 is closed.
>(This is excatly the case with recursive invocation
>of gmake jobs with stdio redirected to pipes)...

1) What's "gmake"?

2) Why shouldn't it "set an error" if handle 0 is closed?

3) Why would anyone do a dup(dup(-1))?

4) Why would setting nh to anything affect this code?  This code path is
   only invoked for /cygdrive or /proc style paths.

If you have a specific problem, you should provide a test case.  I don't
see any problems with recursive invocation of gmake jobs with stdio.

cgf

>---------------------------------
>
>FILE: fhandler.cc
>LINE: ~886
>
>int
>fhandler_base::dup (fhandler_base *child)
>{
>  debug_printf ("in fhandler_base dup");
>
>  HANDLE nh;
>  if (get_nohandle ())
>    nh = NULL;
>  else if (!DuplicateHandle (hMainProc, get_handle(), hMainProc, &nh, 0, TRUE,
>DUPLICATE_SAME_ACCESS))
>    {
>      system_printf ("dup(%s) failed, handle %x, %E",
>     get_name (), get_handle());
>      __seterrno ();
>      return -1;
>    }
>
>  child->set_io_handle (nh);
>  return 0;
>}
>
>
>
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