shm.cc

cygwin, 著名的在win32下模拟unix操作系统的东东

  return request.shmid ();
}

/*---------------------------------------------------------------------------*
 * client_shmmgr::fixup_shms_after_fork ()
 *
 * The hFileMap handles are non-inheritable: so they have to be
 * re-acquired from cygserver.
 *
 * Nb. This routine need not be thread-safe as it is only called at startup.
 *---------------------------------------------------------------------------*/

int
client_shmmgr::fixup_shms_after_fork ()
{
  debug_printf ("re-attaching to shm segments: %d attached", _shmat_cnt);

  {
    int length = 0;
    for (segment_t *segptr = _segments_head; segptr; segptr = segptr->next)
      length += 1;

    if (_shmat_cnt != length)
      {
	system_printf (("state inconsistent: "
			"_shmat_cnt = %d, length of segments list = %d"),
		       _shmat_cnt, length);
	return 1;
      }
  }

  for (segment_t *segptr = _segments_head; segptr; segptr = segptr->next)
    if (!attach (segptr->shmid,
		 segptr->shmaddr,
		 segptr->shmflg & ~SHM_RND,
		 segptr->hFileMap))
      {
	system_printf ("fatal error re-attaching to shm segment %d",
		       segptr->shmid);
	return 1;
      }

  if (_shmat_cnt)
    debug_printf ("re-attached all %d shm segments", _shmat_cnt);

  return 0;
}

/*---------------------------------------------------------------------------*
 * client_shmmgr::client_shmmgr ()
 *---------------------------------------------------------------------------*/

client_shmmgr::client_shmmgr ()
{
  InitializeCriticalSection (&_segments_lock);
}

/*---------------------------------------------------------------------------*
 * client_shmmgr::~client_shmmgr ()
 *---------------------------------------------------------------------------*/

client_shmmgr::~client_shmmgr ()
{
  DeleteCriticalSection (&_segments_lock);
}

/*---------------------------------------------------------------------------*
 * client_shmmgr::find ()
 *---------------------------------------------------------------------------*/

client_shmmgr::segment_t *
client_shmmgr::find (const void *const shmaddr, segment_t **previous)
{
  if (previous)
    *previous = NULL;

  for (segment_t *segptr = _segments_head; segptr; segptr = segptr->next)
    if (segptr->shmaddr == shmaddr)
      return segptr;
    else if (segptr->shmaddr > shmaddr) // The list is sorted by shmaddr.
      return NULL;
    else if (previous)
      *previous = segptr;

  return NULL;
}

/*---------------------------------------------------------------------------*
 * client_shmmgr::attach ()
 *
 * The body of shmat (), also used by fixup_shms_after_fork ().
 *---------------------------------------------------------------------------*/

void *
client_shmmgr::attach (const int shmid,
		       const void *shmaddr,
		       const int shmflg,
		       HANDLE & hFileMap)
{
  client_request_shm request (shmid, shmflg);

  if (request.make_request () == -1 || request.error_code ())
    {
      syscall_printf (("-1 [%d] = "
		       "shmat (shmid = %d, shmaddr = %p, shmflg = 0%o)"),
		      request.error_code (), shmid, shmaddr, shmflg);
      set_errno (request.error_code ());
      return NULL;
    }

  int result = 0;

  const DWORD access = (shmflg & SHM_RDONLY) ? FILE_MAP_READ : FILE_MAP_WRITE;

  if (shmaddr && (shmflg & SHM_RND))
    shmaddr = (char *) shmaddr - ((ssize_t) shmaddr % SHMLBA);

  void *const ptr =
    MapViewOfFileEx (request.hFileMap (), access, 0, 0, 0, (void *) shmaddr);

  if (!ptr)
    {
      syscall_printf (("failed to map view "
		       "[shmid = %d, handle = %p, shmaddr = %p]: %E"),
		      shmid, request.hFileMap (), shmaddr);
      result = EINVAL;		// FIXME
    }
  else if (shmaddr && ptr != shmaddr)
    {
      syscall_printf (("failed to map view at requested address "
		       "[shmid = %d, handle = %p]: "
		       "requested address = %p, mapped address = %p"),
		      shmid, request.hFileMap (),
		      shmaddr, ptr);
      result = EINVAL;		// FIXME
    }

  if (result != 0)
    {
      if (!CloseHandle (request.hFileMap ()))
	syscall_printf (("failed to close file map handle "
			 "[shmid = %d, handle = %p]: %E"),
			shmid, request.hFileMap ());

      client_request_shm dt_req (shmid);

      if (dt_req.make_request () == -1 || dt_req.error_code ())
	syscall_printf ("shmdt request failed [shmid = %d, handle = %p]: %s",
			shmid, request.hFileMap (),
			strerror (dt_req.error_code ()));

      set_errno (result);
      return NULL;
    }

  hFileMap = request.hFileMap ();
  return ptr;
}

/*---------------------------------------------------------------------------*
 * client_shmmgr::new_segment ()
 *
 * Allocate a new segment for the given shmid, file map and address
 * and insert into the segment map.
 *---------------------------------------------------------------------------*/

client_shmmgr::segment_t *
client_shmmgr::new_segment (const int shmid,
			    const void *const shmaddr,
			    const int shmflg,
			    const HANDLE hFileMap)
{
  assert (ipc_ext2int_subsys (shmid) == IPC_SHMOP);
  assert (hFileMap);
  assert (shmaddr);

  segment_t *previous = NULL;	// Insert pointer.

  const segment_t *const tmp = find (shmaddr, &previous);

  assert (!tmp);
  assert (previous							\
	  ? (!previous->next || previous->next->shmaddr > shmaddr)	\
	  : (!_segments_head || _segments_head->shmaddr > shmaddr));

  segment_t *const segptr =
    safe_new (segment_t, shmid, shmaddr, shmflg, hFileMap);

  assert (segptr);

  if (previous)
    {
      segptr->next = previous->next;
      previous->next = segptr;
    }
  else
    {
      segptr->next = _segments_head;
      _segments_head = segptr;
    }

  const long cnt = InterlockedIncrement (&_shmat_cnt);
  assert (cnt > 0);

  return segptr;
}

/*---------------------------------------------------------------------------*
 * shmat ()
 *---------------------------------------------------------------------------*/

extern "C" void *
shmat (const int shmid, const void *const shmaddr, const int shmflg)
{
  sigframe thisframe (mainthread);
  return shmmgr.shmat (shmid, shmaddr, shmflg);
}

/*---------------------------------------------------------------------------*
 * shmctl ()
 *---------------------------------------------------------------------------*/

extern "C" int
shmctl (const int shmid, const int cmd, struct shmid_ds *const buf)
{
  sigframe thisframe (mainthread);
  return shmmgr.shmctl (shmid, cmd, buf);
}

/*---------------------------------------------------------------------------*
 * shmdt ()
 *---------------------------------------------------------------------------*/

extern "C" int
shmdt (const void *const shmaddr)
{
  sigframe thisframe (mainthread);
  return shmmgr.shmdt (shmaddr);
}

/*---------------------------------------------------------------------------*
 * shmget ()
 *---------------------------------------------------------------------------*/

extern "C" int
shmget (const key_t key, const size_t size, const int shmflg)
{
  sigframe thisframe (mainthread);
  return shmmgr.shmget (key, size, shmflg);
}

/*---------------------------------------------------------------------------*
 * fixup_shms_after_fork ()
 *---------------------------------------------------------------------------*/

int __stdcall
fixup_shms_after_fork ()
{
  return shmmgr.fixup_shms_after_fork ();
}

/*---------------------------------------------------------------------------*
 * client_request_shm::client_request_shm ()
 *---------------------------------------------------------------------------*/

client_request_shm::client_request_shm (const int shmid, const int shmflg)
  : client_request (CYGSERVER_REQUEST_SHM, &_parameters, sizeof (_parameters))
{
  _parameters.in.shmop = SHMOP_shmat;

  _parameters.in.shmid = shmid;
  _parameters.in.shmflg = shmflg;

  _parameters.in.cygpid = getpid ();
  _parameters.in.winpid = GetCurrentProcessId ();
  _parameters.in.uid = geteuid ();
  _parameters.in.gid = getegid ();

  msglen (sizeof (_parameters.in));
}

/*---------------------------------------------------------------------------*
 * client_request_shm::client_request_shm ()
 *---------------------------------------------------------------------------*/

client_request_shm::client_request_shm (const int shmid,
					const int cmd,
					const struct shmid_ds *const buf)
  : client_request (CYGSERVER_REQUEST_SHM, &_parameters, sizeof (_parameters))
{
  _parameters.in.shmop = SHMOP_shmctl;

  _parameters.in.shmid = shmid;
  _parameters.in.cmd = cmd;
  if (buf)
    _parameters.in.ds = *buf;

  _parameters.in.cygpid = getpid ();
  _parameters.in.winpid = GetCurrentProcessId ();
  _parameters.in.uid = geteuid ();
  _parameters.in.gid = getegid ();

  msglen (sizeof (_parameters.in));
}

/*---------------------------------------------------------------------------*
 * client_request_shm::client_request_shm ()
 *---------------------------------------------------------------------------*/

client_request_shm::client_request_shm (const int shmid)
  : client_request (CYGSERVER_REQUEST_SHM, &_parameters, sizeof (_parameters))
{
  _parameters.in.shmop = SHMOP_shmdt;

  _parameters.in.shmid = shmid;

  _parameters.in.cygpid = getpid ();
  _parameters.in.winpid = GetCurrentProcessId ();
  _parameters.in.uid = geteuid ();
  _parameters.in.gid = getegid ();

  msglen (sizeof (_parameters.in));
}

/*---------------------------------------------------------------------------*
 * client_request_shm::client_request_shm ()
 *---------------------------------------------------------------------------*/

client_request_shm::client_request_shm (const key_t key,
					const size_t size,
					const int shmflg)
  : client_request (CYGSERVER_REQUEST_SHM, &_parameters, sizeof (_parameters))
{
  _parameters.in.shmop = SHMOP_shmget;

  _parameters.in.key = key;
  _parameters.in.size = size;
  _parameters.in.shmflg = shmflg;

  _parameters.in.cygpid = getpid ();
  _parameters.in.winpid = GetCurrentProcessId ();
  _parameters.in.uid = geteuid ();
  _parameters.in.gid = getegid ();

  msglen (sizeof (_parameters.in));
}