AC_DEFUN([CONFTEST_FDPASS],[[
 AC_LANG_SOURCE([[
 $1 

 #ifdef HAVE_SYS_TYPES_H

 #include <sys/types.h>

 #endif

 #include <sys/wait.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <string.h>

 #ifdef HAVE_SYS_UIO_H

 #include <sys/uio.h>

 #endif

 #include <signal.h>
 #include <sys/socket.h>
 

 #if !defined CMSG_SPACE || !defined CMSG_LEN
 #ifndef ALIGN
 #define ALIGN(len) len
 #endif
 
 #ifndef CMSG_SPACE
 #define CMSG_SPACE(len) (ALIGN(sizeof(struct cmsghdr)) + ALIGN(len))
 #endif
 
 #ifndef CMSG_LEN
 #define CMSG_LEN(len) (ALIGN(sizeof(struct cmsghdr)) + len)
 #endif
 #endif

 
 #define TEST "test"
 

 static int send_fd(int s, int fd)

 {
     struct msghdr msg;
     struct cmsghdr *cmsg;
     unsigned char fdbuf[CMSG_SPACE(sizeof(int))];
     struct iovec iov[1];

     char dummy[] = "";

     iov[0].iov_base = dummy;

     iov[0].iov_len = 1;
 
     memset(&msg, 0, sizeof(msg));
     msg.msg_control = fdbuf;
     /* must send/receive at least one byte */
     msg.msg_iov = iov;
     msg.msg_iovlen = 1;
     msg.msg_controllen = CMSG_LEN(sizeof(int));
 
     cmsg = CMSG_FIRSTHDR(&msg);
     cmsg->cmsg_len = CMSG_LEN(sizeof(int));
     cmsg->cmsg_level = SOL_SOCKET;
     cmsg->cmsg_type = SCM_RIGHTS;
     *(int *)CMSG_DATA(cmsg) = fd;
 
     if (sendmsg(s, &msg, 0) == -1) {
         perror("sendmsg");
         close(s);
         return -1;
     }
     return 0;
 }
 

 static int testfd(int desc)

 {
     char buf[256];
     if(read(desc, buf, sizeof(buf)) != sizeof(TEST)) {
         fprintf(stderr, "test data not received correctly!");
         return 1;
     }
     return memcmp(buf, TEST, sizeof(TEST));
 }
 

 static int recv_fd(int desc)

 {
     unsigned char buf[CMSG_SPACE(sizeof(int))];
     struct msghdr msg;
     struct cmsghdr *cmsg;
     struct iovec iov[1];
     char dummy;
     int ret=2;
 
     memset(&msg, 0, sizeof(msg));
     iov[0].iov_base = &dummy;
     iov[0].iov_len = 1;
     msg.msg_iov = iov;
     msg.msg_iovlen = 1;
     msg.msg_control = buf;
     msg.msg_controllen = sizeof(buf);
 
     if (recvmsg(desc, &msg, 0) == -1) {
         perror("recvmsg failed!");
         return -1;
     }
     if ((msg.msg_flags & MSG_TRUNC) || (msg.msg_flags & MSG_CTRUNC)) {
         fprintf(stderr, "control message truncated");
         return -1;
     }
     for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
         cmsg = CMSG_NXTHDR(&msg, cmsg)) {
         if (cmsg->cmsg_len == CMSG_LEN(sizeof(int)) &&
             cmsg->cmsg_level == SOL_SOCKET &&
             cmsg->cmsg_type == SCM_RIGHTS) {
             int fd = *(int *)CMSG_DATA(cmsg);
             ret = testfd(fd);
             close(fd);
         }
     }
     return ret;
 }
 
 int main(void)
 {
     int fd[2];
     int pip[2];
     pid_t pid;
     int status;
 
     if(pipe(pip)) {
         perror("pipe");
         return 1;
     }
 
     if(socketpair(AF_UNIX, SOCK_STREAM, 0, fd)) {
         perror("socketpair");
         return 1;
     }
 
     if((pid=fork()) < 0) {
         perror("fork");
     } else if (!pid) {
         exit( recv_fd(fd[1]) );
     } else {
         /* parent */
         if(send_fd(fd[0], pip[0]) == -1) {
             kill(pid, 9);
             waitpid(pid, NULL, 0);
             return 2;
         }

         if(write(pip[1], TEST, sizeof(TEST)) != sizeof(TEST)) {
 		close(pip[1]);
 		return -1;
 	}

         close(pip[1]);
         waitpid(pid, &status, 0);
     }
     return status;
 }
 ]])
 ]])
 
 AC_DEFUN([AC_C_FDPASSING],[
 dnl Check if we can do fd passing
 dnl Submitted by Richard Lyons <frob-clamav@webcentral.com.au>
 AC_CHECK_FUNCS([recvmsg sendmsg])
 AC_CACHE_CHECK([for msg_control field in struct msghdr],
     [ac_cv_have_control_in_msghdr], [
     AC_TRY_COMPILE(
 [
 #define _XOPEN_SOURCE 500

 #ifdef HAVE_SYS_TYPES_H

 #include <sys/types.h>

 #endif

 #include <sys/socket.h>

 #ifdef HAVE_SYS_UIO_H

 #include <sys/uio.h>

 #endif

 ],
 [
 #ifdef msg_control
 #error msg_control defined
 #endif
 struct msghdr m;
 m.msg_control = 0;
 return 0;
 ], [ ac_cv_have_control_in_msghdr="yes" ], [ ac_cv_have_control_in_msghdr="no" ])
 ])
 if test "x$ac_cv_have_control_in_msghdr" = "xyes" ; then
     AC_DEFINE([HAVE_CONTROL_IN_MSGHDR],1,[ancillary data style fd pass])
 
     dnl Check whether FD passing works <edwin@clamav.net>
     AC_MSG_CHECKING([BSD 4.4 / RFC2292 style fd passing])
     AC_ARG_ENABLE([fdpassing],[  --disable-fdpassing        don't build file descriptor passing support],
         want_fdpassing=$enableval, want_fdpassing="yes")
 
     if test "x$want_fdpassing" = "xyes"; then
         dnl Try without _XOPEN_SOURCE first
         AC_RUN_IFELSE(CONFTEST_FDPASS([]), [have_fdpass=1; fdpass_need_xopen=0], [have_fdpass=0],[have_fdpass=0])
 
         if test $have_fdpass = 0; then
             AC_RUN_IFELSE(CONFTEST_FDPASS([#define _XOPEN_SOURCE 500]), [have_fdpass=1; fdpass_need_xopen=1],[have_fdpass=0],[have_fdpass=0])
         fi
 
         if test $have_fdpass = 1; then
             AC_DEFINE([HAVE_FD_PASSING],1,[have working file descriptor passing support])
             if test $fdpass_need_xopen = 1; then
                 AC_DEFINE([FDPASS_NEED_XOPEN],1,[whether _XOPEN_SOURCE needs to be defined for fd passing to work])
                 AC_MSG_RESULT([yes, by defining _XOPEN_SOURCE])
             else
                 AC_MSG_RESULT([yes])
             fi
         else
             AC_MSG_RESULT([no])
         fi
 
     else
         AC_MSG_RESULT([disabled])
     fi
 fi
 ])