/* Return point to next ancillary data entry in message header.   Copyright (C) 1997, 1998 Free Software Foundation, Inc.   This file is part of the GNU C Library.   The GNU C Library is free software; you can redistribute it and/or   modify it under the terms of the GNU Library General Public License as   published by the Free Software Foundation; either version 2 of the   License, or (at your option) any later version.   The GNU C Library is distributed in the hope that it will be useful,   but WITHOUT ANY WARRANTY; without even the implied warranty of   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU   Library General Public License for more details.   You should have received a copy of the GNU Library General Public   License along with the GNU C Library; see the file COPYING.LIB.  If not,   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,   Boston, MA 02111-1307, USA.  */#define __FORCE_GLIBC#include <features.h>#include <sys/socket.h>struct cmsghdr *__cmsg_nxthdr (struct msghdr *mhdr, struct cmsghdr *cmsg){  if ((size_t) cmsg->cmsg_len < sizeof (struct cmsghdr))    /* The kernel header does this so there may be a reason.  */    return NULL;  cmsg = (struct cmsghdr *) ((unsigned char *) cmsg			     + CMSG_ALIGN (cmsg->cmsg_len));  if ((unsigned char *) (cmsg + 1) >= ((unsigned char *) mhdr->msg_control				       + mhdr->msg_controllen)      || ((unsigned char *) cmsg + CMSG_ALIGN (cmsg->cmsg_len)	  >= ((unsigned char *) mhdr->msg_control + mhdr->msg_controllen)))    /* No more entries.  */    return NULL;  return cmsg;}