text: /* Return point to next ancillary data entry in message header.
     Copyright (C) 1997, 1998, 2001 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 Lesser General Public
     License as published by the Free Software Foundation; either
     version 2.1 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
     Lesser General Public License for more details.
  
     You should have received a copy of the GNU Lesser General Public
     License along with the GNU C Library; if not, write to the Free
     Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
     02111-1307 USA.  */
  
  #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;
  }
  