tests/sys_mman.h

   1 // Replacement for sys/mman.h which factors out platform differences.
   2
   3 #include <sys/mman.h>
   4
   5 #if defined(VGO_darwin)
   6 #  define MAP_ANONYMOUS MAP_ANON
   7 #endif
   8
   9
  10 #include <assert.h>
  11 #include <unistd.h>
  12
  13 // Map a page, then unmap it, then return that address.  That
  14 // guarantees to give an address which will fault when accessed,
  15 // without making any assumptions about the layout of the address
  16 // space.
  17
  18 __attribute__((unused))
  19 static void* get_unmapped_page(void)
  20 {
  21    void* ptr;
  22    int r;
  23    long pagesz = sysconf(_SC_PAGE_SIZE);
  24    assert(pagesz == 4096 || pagesz == 16384 || pagesz == 65536);
  25    ptr = mmap(0, pagesz, PROT_READ, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
  26    assert(ptr != (void*)-1);
  27    r = munmap(ptr, pagesz);
  28    assert(r == 0);
  29    return ptr;
  30 }
  31