1 /* Return point to next ancillary data entry in message header. 2 Copyright (C) 1997, 1998, 2001 Free Software Foundation, Inc. 3 This file is part of the GNU C Library. 4 5 The GNU C Library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Lesser General Public 7 License as published by the Free Software Foundation; either 8 version 2.1 of the License, or (at your option) any later version. 9 10 The GNU C Library is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public 16 License along with the GNU C Library; if not, see 17 <http://www.gnu.org/licenses/>. */ 18 19 #include <features.h> 20 #include <stddef.h> 21 /* Prevent math.h from defining a colliding inline */ 22 #undef __USE_EXTERN_INLINES 23 #include <sys/socket.h> 24 25 26 struct cmsghdr * __cmsg_nxthdr(struct msghdr * mhdr,struct cmsghdr * cmsg)27__cmsg_nxthdr (struct msghdr *mhdr, struct cmsghdr *cmsg) 28 { 29 if ((size_t) cmsg->cmsg_len < sizeof (struct cmsghdr)) 30 /* The kernel header does this so there may be a reason. */ 31 return NULL; 32 33 cmsg = (struct cmsghdr *) ((unsigned char *) cmsg 34 + CMSG_ALIGN (cmsg->cmsg_len)); 35 if ((unsigned char *) (cmsg + 1) > ((unsigned char *) mhdr->msg_control 36 + mhdr->msg_controllen) 37 || ((unsigned char *) cmsg + CMSG_ALIGN (cmsg->cmsg_len) 38 > ((unsigned char *) mhdr->msg_control + mhdr->msg_controllen))) 39 /* No more entries. */ 40 return NULL; 41 return cmsg; 42 } 43 libc_hidden_def(__cmsg_nxthdr) 44