include/param.h: Dont use ARG_MAX from kernel headers

* Use getrlimit for ARG_MAX in sysconf on nptl.
* Define NCARGS directly instead of ARG_MAX

Signed-off-by: Khem Raj <raj.khem@gmail.com>

include/sys/param.h

@@ -1,4 +1,4 @@
-/* Copyright (C) 1995,1996,1997,2000,2001,2003 Free Software Foundation, Inc.
+/* Copyright (C) 1995-1997,2000,2001,2003,2008 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -19,10 +19,20 @@
 #ifndef _SYS_PARAM_H
 #define _SYS_PARAM_H	1
 
+#ifndef ARG_MAX
+# define __undef_ARG_MAX
+#endif
+
 #include <limits.h>
 #include <linux/limits.h>
 #include <linux/param.h>
 
+/* The kernel headers defines ARG_MAX.  The value is wrong, though.  */
+#ifndef __undef_ARG_MAX
+# undef ARG_MAX
+# undef __undef_ARG_MAX
+#endif
+
 /* BSD names for some <limits.h> values.  */
 
 #define	NBBY		CHAR_BIT
@@ -31,12 +41,12 @@
 #endif
 #define	MAXSYMLINKS	20
 #define	CANBSIZ		MAX_CANON
-#define	NCARGS		ARG_MAX
 #define MAXPATHLEN	PATH_MAX
-/* The following is not really correct but it is a value we used for a
+/* The following are not really correct but it is a value we used for a
    long time and which seems to be usable.  People should not use NOFILE
-   anyway.  */
+   and NCARGS anyway.  */
 #define NOFILE		256
+#define	NCARGS		131072
 
 
 #include <sys/types.h>

libc/sysdeps/linux/common/bits/local_lim.h

@@ -1,5 +1,5 @@
 /* Minimum guaranteed maximum values for system limits.  Linux version.
-   Copyright (C) 1993-1998,2000,2002,2003,2004 Free Software Foundation, Inc.
+   Copyright (C) 1993-1998,2000,2002-2004,2008 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -31,6 +31,9 @@
 #ifndef OPEN_MAX
 # define __undef_OPEN_MAX
 #endif
+#ifndef ARG_MAX
+# define __undef_ARG_MAX
+#endif
 
 /* The kernel sources contain a file with all the needed information.  */
 #include <linux/limits.h>
@@ -50,6 +53,11 @@
 # undef OPEN_MAX
 # undef __undef_OPEN_MAX
 #endif
+/* Have to remove ARG_MAX?  */
+#ifdef __undef_ARG_MAX
+# undef ARG_MAX
+# undef __undef_ARG_MAX
+#endif
 
 /* The number of data keys per process.  */
 #define _POSIX_THREAD_KEYS_MAX	128

libc/unistd/sysconf.c

@@ -36,6 +36,8 @@
 #endif
 #ifdef __UCLIBC_HAS_THREADS_NATIVE__
 #include <sysdep.h>
+#include <sys/resource.h>
+
 #endif
 
 #ifndef num_present_cpus
@@ -81,9 +83,16 @@
 #define RETURN_FUNCTION(f) return f;
 #endif /* _UCLIBC_GENERATE_SYSCONF_ARCH */
 
+/* Legacy value of ARG_MAX.  The macro is now not defined since the
+   actual value varies based on the stack size.  */
+#define legacy_ARG_MAX 131072
+
 /* Get the value of the system variable NAME.  */
 long int sysconf(int name)
 {
+#ifdef __UCLIBC_HAS_THREADS_NATIVE__
+      struct rlimit rlimit;
+#endif
   switch (name)
     {
     default:
@@ -91,7 +100,11 @@ long int sysconf(int name)
       return -1;
 
     case _SC_ARG_MAX:
-#ifdef	ARG_MAX
+#ifdef __UCLIBC_HAS_THREADS_NATIVE__
+      /* Use getrlimit to get the stack limit.  */
+      if (getrlimit (RLIMIT_STACK, &rlimit) == 0)
+          return MAX (legacy_ARG_MAX, rlimit.rlim_cur / 4);
+#elif defined ARG_MAX
       return ARG_MAX;
 #else
       RETURN_NEG_1;