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Date: Wed, 8 Sep 2004 12:06:57 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: win95 pipe problems -- report + testcase + patch (was: Re: [ANNOUNCEMENT] Updated: cygwin-1.5.11-1)
Message-ID: <20040908100657.GC20537@cygbert.vinschen.de>
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References: <200409050451 DOT i854pPi21887 AT esds DOT vss DOT fsi DOT com> <n2m-g DOT chlod0 DOT 3vvdk95 DOT 1 AT buzzy-box DOT bavag>
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On Sep  8 01:55, Bas van Gompel wrote:
> This fix trips on a bug in (my) windows 95 (OSR2):
> It's CreateNamedPipe returns 0 instead of -1 (INVALID_HANDLE_VALUE),
> causing all operations on pipes to fail.
> [...]
> A patch to work around this in cygwin could be: (WFM)
> 
> ==== Begin pipe-w95.diff ====
> --- src/winsup/cygwin/pipe.cc	3 Sep 2004 01:32:02 -0000	1.62
> +++ src/winsup/cygwin/pipe.cc	7 Sep 2004 19:09:55 -0000
> @@ -259,6 +259,7 @@ create_selectable_pipe (PHANDLE read_pip
>           the pipe was not created earlier by some other process, even if
>           the pid has been reused.  We avoid FILE_FLAG_FIRST_PIPE_INSTANCE
>           because that is only available for Win2k SP2 and WinXP.  */
> +      SetLastError(0);
>        read_pipe = CreateNamedPipe (pipename,
>                                     PIPE_ACCESS_INBOUND,
>                                     PIPE_TYPE_BYTE | PIPE_READMODE_BYTE,
> @@ -268,13 +269,13 @@ create_selectable_pipe (PHANDLE read_pip
>                                     NMPWAIT_USE_DEFAULT_WAIT,
>                                     sa_ptr);
>  
> -      if (read_pipe != INVALID_HANDLE_VALUE)
> +      DWORD err = GetLastError ();
> +      if ((read_pipe || !err) && read_pipe != INVALID_HANDLE_VALUE)
>          {
>            debug_printf ("pipe read handle %p", read_pipe);
>            break;
>          }
>  
> -      DWORD err = GetLastError ();
>        switch (err)
>          {
>          case ERROR_PIPE_BUSY:
> 
> ===== End pipe-w95.diff =====
> 
> I hope this patch is small enough to qualify as `trivial', as I

It is.  I'm just wondering if it is really necessary to assume, that
CreateNamedPipe will ever return NULL as a vaild handle.  I'd assume
that the following patch is sufficient:

--- pipe.cc.ORIG        2004-09-08 11:58:57.000000000 +0200
+++ pipe.cc     2004-09-08 11:59:05.000000000 +0200
@@ -268,7 +268,8 @@ create_selectable_pipe (PHANDLE read_pip
                                    NMPWAIT_USE_DEFAULT_WAIT,
                                    sa_ptr);
 
-      if (read_pipe != INVALID_HANDLE_VALUE)
+      /* Win 95 seems to return NULL instead of INVALID_HANDLE_VALUE */
+      if (read_pipe && read_pipe != INVALID_HANDLE_VALUE)
         {
           debug_printf ("pipe read handle %p", read_pipe);
           break;


> haven't received any reply to my legal query (yet). (Did the reply
> get blocked from the list?)

No, there was no reply so far, unfortunately.  I'm sorry.  I'll try to
nudge our legal department again.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          mailto:cygwin AT cygwin DOT com
Red Hat, Inc.

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