dnl Check for mmap()
 dnl AC_FUNC_MMAP checks for private fixed mappings, we don't need
 dnl fixed mappings, so check only wether private mappings work.
 dnl AC_FUNC_MMAP would fail on HP-UX for example.
 AC_DEFUN([AC_C_FUNC_MMAP_PRIVATE],
 [ 
 	AC_CACHE_CHECK([for working mmap], [ac_cv_c_mmap_private],
 	[
 		AC_RUN_IFELSE([AC_LANG_SOURCE([
 #include <unistd.h>
 #include <stdlib.h>
 #include <sys/mman.h>
 #ifdef HAVE_SYS_TYPES_H
 #include <sys/types.h>
 #endif
 #ifdef HAVE_SYS_STAT_H
 #include <sys/stat.h>
 #endif
 #include <fcntl.h> 
 int main(void)
 {
 	char *data, *data2, *data3;

 	size_t i, datasize = 1024;

 	int fd;
 
   	/* First, make a file with some known garbage in it. */
 	data = (char*) malloc(datasize);
 	if(!data)
 		return 1;
 	for(i=0;i<datasize;i++)
 		*(data + i) = rand();
 	umask(0);
 	fd = creat("conftest.mmap", 0600);
 	if(fd < 0)
 		return 1;
 	if(write (fd, data, datasize) != datasize)
 		return 1;
 	close(fd);
 	fd = open("conftest.mmap", O_RDWR);
 	if (fd < 0)
 		return 1;
 	/* Next, try to mmap the file at a fixed address which already has
 	   something else allocated at it.  If we can, also make sure that
 	   we see the same garbage.  */
 	data2 = mmap(NULL, sizeof(data), PROT_READ | PROT_WRITE,
 		MAP_PRIVATE, fd, 0L);	
 	if(data2 == MAP_FAILED)
 		return 2;
 	for(i=0;i<sizeof(data);i++)
 		if(*(data + i) != *(data2+ i))
 			return 3;
 	  /* Finally, make sure that changes to the mapped area do not
      	     percolate back to the file as seen by read().  (This is a bug on
              some variants of i386 svr4.0.)  */
 	  for (i = 0; i < datasize; ++i)
 	    *(data2 + i) = *(data2 + i) + 1;
 	data3 = (char*) malloc(datasize);
 	if(!data3)
 		return 1;
 	if(read (fd, data3, datasize) != datasize)
 		return 1;
 	for(i=0;i<sizeof(data);i++)
 		if(*(data + i) != *(data3 + i))
 			return 3;
 	close(fd);
 	return 0;
 }])],
 	[ac_cv_c_mmap_private=yes],
 	[ac_cv_c_mmap_private=no],
 	[ac_cv_c_mmap_private=no])])
 if test $ac_cv_c_mmap_private = yes; then
 	AC_DEFINE(HAVE_MMAP, 1,
 		[Define to 1 if you have a working `mmap' system call that supports MAP_PRIVATE.])
 fi
 rm -f conftest.mmap
 ])
 
 

 AC_DEFUN([AC_C_FUNC_MMAP_ANONYMOUS],
 [
 	AC_CACHE_CHECK([for MAP_ANON(YMOUS)], [ac_cv_c_mmap_anonymous],[
 		ac_cv_c_mmap_anonymous='no'

 		AC_LINK_IFELSE(

 			[AC_LANG_PROGRAM([[#include <sys/mman.h>]], [[mmap((void *)0, 0, PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);]])],
 			[ac_cv_c_mmap_anonymous='MAP_ANONYMOUS'],
 			[
 				AC_LINK_IFELSE(

 					[AC_LANG_PROGRAM([[
 /* OPENBSD WORKAROUND - DND*/
 #include <sys/types.h>
 /* OPENBSD WORKAROUND - END*/
 #include <sys/mman.h>
 ]], [[mmap((void *)0, 0, PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);]])],

 					[ac_cv_c_mmap_anonymous='MAP_ANON']

 				)
 			]
 		)
 	])
 	if test "$ac_cv_c_mmap_anonymous" != "no"; then
 		AC_DEFINE_UNQUOTED([ANONYMOUS_MAP],[$ac_cv_c_mmap_anonymous],[mmap flag for anonymous maps])
 	fi

 ])

 
 AC_DEFUN([AC_C_FUNC_PAGESIZE],
 [
 ac_cv_c_can_get_pagesize="no"
 AC_CACHE_CHECK([for sysconf(_SC_PAGESIZE)], [ac_cv_c_sysconf_sc_pagesize], [
 	AC_LINK_IFELSE([AC_LANG_PROGRAM([[
 #include <sys/types.h>
 #if HAVE_UNISTD_H
 #include <unistd.h>
 #endif]], [[int x = sysconf(_SC_PAGESIZE);]])],
 	[ac_cv_c_sysconf_sc_pagesize=yes], [ac_cv_c_sysconf_sc_pagesize=no])
 ])
 if test "$ac_cv_c_sysconf_sc_pagesize" = "yes"; then
 	AC_DEFINE([HAVE_SYSCONF_SC_PAGESIZE], 1, [Define to 1 if sysconf(_SC_PAGESIZE) is available])
 	ac_cv_c_can_get_pagesize="yes"
 fi
 AC_CACHE_CHECK([for getpagesize()], [ac_cv_c_getpagesize], [
 	AC_LINK_IFELSE([AC_LANG_PROGRAM([[
 #if HAVE_UNISTD_H
 #include <unistd.h>
 #endif]], [[int x = getpagesize();]])], 
 	[ac_cv_c_getpagesize=yes], [ac_cv_c_getpagesize=no])
 ])
 if test "$ac_cv_c_getpagesize" = "yes"; then
 	AC_DEFINE([HAVE_GETPAGESIZE], 1, [Define to 1 if getpagesize() is available])
 	ac_cv_c_can_get_pagesize="yes"
 fi
 ])