Date: Thu, 11 Sep 1997 14:18:25 +0200 (METDST)
From: Robert Hoehne <robert DOT hoehne AT mathematik DOT tu-chemnitz DOT de>
To: Oberhumer Markus <k3040e4 AT c210 DOT edvz DOT uni-linz DOT ac DOT at>
Cc: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>, djgpp-workers AT delorie DOT com
Subject: Re: c1args.c patches
In-Reply-To: <199709101444.KAA20690@delorie.com>
Message-Id: <Pine.HPP.3.95q.970911141305.26019C-100000@newton.mathematik.tu-chemnitz.de>
Mime-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Precedence: bulk

On Wed, 10 Sep 1997, Oberhumer Markus wrote:

> xargs has the annoying limitation of the size of the transfer buffer

Oh No!! It is not the limited tarnsfer buffer but the way like
xargs is designed. It is probaly the only program currently
in use on DJGPP which examines the system limitation for the
maximal argument lenght. And this is for DJGPP 4096!!

Here is the relevant part from xargs.c which shows this:

-----------------
  orig_arg_max = ARG_MAX - 2048; /* POSIX.2 requires subtracting 2048.  */
  arg_max = orig_arg_max;
  /* Sanity check for systems with huge ARG_MAX defines (e.g., Suns which
     have it at 1 meg).  Things will work fine with a large ARG_MAX but it
     will probably hurt the system more than it needs to; an array of this
     size is allocated.  */
  if (arg_max > 20 * 1024)
    arg_max = 20 * 1024;
  /* Take the size of the environment into account.  */
  arg_max -= env_size (environ);
  if (arg_max <= 0)
    error (1, 0, "environment is too large for exec");
 
------------------

And here is now the patch for limits.h, by adjusting this value
to the current used transfer buffer size:

--- include/limits.h~	Wed Jul  2 22:13:44 1997
+++ include/limits.h	Thu Sep 11 08:16:32 1997
@@ -27,7 +27,7 @@
 
 #ifndef __STRICT_ANSI__
 
-#define _POSIX_ARG_MAX		4096	/* but only for exec's to other djgpp programs */
+#define _POSIX_ARG_MAX		16384	/* but only for exec's to other djgpp programs */
 #define _POSIX_CHILD_MAX	6	/* really limited by memory */
 #define _POSIX_LINK_MAX		1	/* POSIX says 8, but DOS says 1 */
 #define _POSIX_MAX_CANON	126	/* POSIX says 255, but DOS says 126 */
@@ -43,7 +43,7 @@
 
 #define NGROUPS_MAX		0
 
-#define ARG_MAX			4096
+#define ARG_MAX			16384
 #define CHILD_MAX		6
 /* #define OPEN_MAX		20 - DOS can change this */
 /* #define STREAM_MAX		20 - DOS can change this */



Of course, when the tb size will change (the default) in the next
DJGPP evrsion, this should be reflected here too.

Robert