Add cmsg_nxthdr function for the cases where the headers

do not so it inline.

libc/sysdeps/linux/common/Makefile

@@ -26,7 +26,8 @@ include $(TOPDIR)Rules.mak
 
 CSRC=	waitpid.c kernel_version.c statfix.c getdnnm.c gethstnm.c \
 	mkfifo.c setegid.c wait.c errno.c getpagesize.c seteuid.c \
-	wait3.c setpgrp.c getdtablesize.c create_module.c ptrace.c
+	wait3.c setpgrp.c getdtablesize.c create_module.c ptrace.c \
+	cmsg_nxthdr.c
 COBJS=$(patsubst %.c,%.o, $(CSRC))
 
 MSRC=syscalls.c

libc/sysdeps/linux/common/cmsg_nxthdr.c

@@ -0,0 +1,39 @@
+/* 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.  */
+
+#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;
+}