glibc/sysdeps/unix/sysv/linux/cmsg_nxthdr.c

40 lines
1.5 KiB
C

/* Return point to next ancillary data entry in message header.
Copyright (C) 1997-2016 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, see
<http://www.gnu.org/licenses/>. */
#include <stddef.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;
}