#undef HOST_HOOKS_GT_PCH_USE_ADDRESS

#define HOST_HOOKS_GT_PCH_USE_ADDRESS linux_gt_pch_use_address

/* Map SIZE bytes of FD+OFFSET at BASE.  Return 1 if we succeeded at

   mapping the data at BASE, -1 if we couldn't.

   It's not possibly to reliably mmap a file using MAP_PRIVATE to

   a specific START address on either hpux or linux.  First we see

   if mmap with MAP_PRIVATE works.  If it does, we are off to the

   races.  If it doesn't, we try an anonymous private mmap since the

   kernel is more likely to honor the BASE address in anonymous maps.

   We then copy the data to the anonymous private map.  This assumes

   of course that we don't need to change the data in the PCH file

   after it is created.

   This approach obviously causes a performance penalty but there is

   little else we can do given the current PCH implementation.  */

static int

linux_gt_pch_use_address (void *base, size_t size, int fd, size_t offset)

{

  void *addr;

  /* We're called with size == 0 if we're not planning to load a PCH

     file at all.  This allows the hook to free any static space that

     we might have allocated at link time.  */

  if (size == 0)

    return -1;

  /* Try to map the file with MAP_PRIVATE.  */

  addr = mmap (base, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, offset);

  if (addr == base)

    return 1;

  if (addr != (void *) MAP_FAILED)

    munmap (addr, size);

  /* Try to make an anonymous private mmap at the desired location.  */

  addr = mmap (base, size, PROT_READ | PROT_WRITE,

	       MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

  if (addr != base)

    {

      if (addr != (void *) MAP_FAILED)

        munmap (addr, size);

      return -1;

    }

  if (lseek (fd, offset, SEEK_SET) == (off_t)-1)

    return -1;

  while (size)

    {

      ssize_t nbytes;

      nbytes = read (fd, base, MIN (size, SSIZE_MAX));

      if (nbytes <= 0)

        return -1;

      base = (char *) base + nbytes;

      size -= nbytes;

    }

  return 1;

}