#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;