cmsg_nxthdr.c 1.6 KB

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  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. The GNU C Library is free software; you can redistribute it and/or
  5. modify it under the terms of the GNU Lesser General Public
  6. License as published by the Free Software Foundation; either
  7. version 2.1 of the License, or (at your option) any later version.
  8. The GNU C Library is distributed in the hope that it will be useful,
  9. but WITHOUT ANY WARRANTY; without even the implied warranty of
  10. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  11. Lesser General Public License for more details.
  12. You should have received a copy of the GNU Lesser General Public
  13. License along with the GNU C Library; if not, write to the Free
  14. Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  15. 02111-1307 USA. */
  16. #define __FORCE_GLIBC
  17. #include <features.h>
  18. #include <sys/socket.h>
  19. libc_hidden_proto(__cmsg_nxthdr)
  20. struct cmsghdr *
  21. __cmsg_nxthdr (struct msghdr *mhdr, struct cmsghdr *cmsg)
  22. {
  23. if ((size_t) cmsg->cmsg_len < sizeof (struct cmsghdr))
  24. /* The kernel header does this so there may be a reason. */
  25. return NULL;
  26. cmsg = (struct cmsghdr *) ((unsigned char *) cmsg
  27. + CMSG_ALIGN (cmsg->cmsg_len));
  28. if ((unsigned char *) (cmsg + 1) > ((unsigned char *) mhdr->msg_control
  29. + mhdr->msg_controllen)
  30. || ((unsigned char *) cmsg + CMSG_ALIGN (cmsg->cmsg_len)
  31. > ((unsigned char *) mhdr->msg_control + mhdr->msg_controllen)))
  32. /* No more entries. */
  33. return NULL;
  34. return cmsg;
  35. }
  36. libc_hidden_def(__cmsg_nxthdr)