#include <u.h>
#define NOPLAN9DEFINES
#include <libc.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <unistd.h>
#include <errno.h>

#ifndef CMSG_ALIGN
#       ifdef __sun__
#               define CMSG_ALIGN _CMSG_DATA_ALIGN
#       else
#               define CMSG_ALIGN(len) (((len)+sizeof(long)-1) & ~(sizeof(long)-1))
#       endif
#endif

#ifndef CMSG_SPACE
#       define CMSG_SPACE(len) (CMSG_ALIGN(sizeof(struct cmsghdr))+CMSG_ALIGN(len))
#endif

#ifndef CMSG_LEN
#       define CMSG_LEN(len) (CMSG_ALIGN(sizeof(struct cmsghdr))+(len))
#endif

int
sendfd(int s, int fd)
{
        char buf[1];
        struct iovec iov;
        struct msghdr msg;
        struct cmsghdr *cmsg;
        int n;
        char cms[CMSG_SPACE(sizeof(int))];
        
        buf[0] = 0;
        iov.iov_base = buf;
        iov.iov_len = 1;

        memset(&msg, 0, sizeof msg);
        msg.msg_iov = &iov;
        msg.msg_iovlen = 1;
        msg.msg_control = (caddr_t)cms;
        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;
        memmove(CMSG_DATA(cmsg), &fd, sizeof(int));

        if((n=sendmsg(s, &msg, 0)) != iov.iov_len)
                return -1;
        return 0;
}

int
recvfd(int s)
{
        int n;
        int fd;
        char buf[1];
        struct iovec iov;
        struct msghdr msg;
        struct cmsghdr *cmsg;
        char cms[CMSG_SPACE(sizeof(int))];

        iov.iov_base = buf;
        iov.iov_len = 1;

        memset(&msg, 0, sizeof msg);
        msg.msg_name = 0;
        msg.msg_namelen = 0;
        msg.msg_iov = &iov;
        msg.msg_iovlen = 1;

        msg.msg_control = (caddr_t)cms;
        msg.msg_controllen = sizeof cms;

        if((n=recvmsg(s, &msg, 0)) < 0)
                return -1;
        if(n == 0){
                werrstr("unexpected EOF");
                return -1;
        }
        cmsg = CMSG_FIRSTHDR(&msg);
        memmove(&fd, CMSG_DATA(cmsg), sizeof(int));
        return fd;
}