/* Return a pointer to a zero-size object in memory.
- Copyright (C) 2009 Free Software Foundation, Inc.
+ Copyright (C) 2009, 2010 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
#include <stdlib.h>
-#if HAVE_MPROTECT
+/* Test whether mmap() and mprotect() are available.
+ We don't use HAVE_MMAP, because AC_FUNC_MMAP would not define it on HP-UX.
+ HAVE_MPROTECT is not enough, because mingw does not have mmap() but has an
+ mprotect() function in libgcc.a. */
+#if HAVE_SYS_MMAN_H && HAVE_MPROTECT
# include <fcntl.h>
# include <unistd.h>
# include <sys/types.h>
# endif
#endif
-/* Return a pointer to a zero-size object in memory, if possible.
+/* Return a pointer to a zero-size object in memory (that is, actually, a
+ pointer to a page boundary where the previous page is readable and writable
+ and the next page is neither readable not writable), if possible.
Return NULL otherwise. */
static void *
{
/* Use mmap and mprotect when they exist. Don't test HAVE_MMAP, because it is
not defined on HP-UX 11 (since it does not support MAP_FIXED). */
-#if HAVE_MPROTECT
+#if HAVE_SYS_MMAN_H && HAVE_MPROTECT
# if HAVE_MAP_ANONYMOUS
const int flags = MAP_ANONYMOUS | MAP_PRIVATE;
const int fd = -1;
{
int pagesize = getpagesize ();
char *two_pages =
- (char *) mmap (NULL, 2 * pagesize, PROT_READ | PROT_WRITE,
- flags, fd, 0);
+ (char *) mmap (NULL, 2 * pagesize, PROT_READ | PROT_WRITE,
+ flags, fd, 0);
if (two_pages != (char *)(-1)
- && mprotect (two_pages + pagesize, pagesize, PROT_NONE) == 0)
- return two_pages + pagesize;
+ && mprotect (two_pages + pagesize, pagesize, PROT_NONE) == 0)
+ return two_pages + pagesize;
}
#endif
return NULL;