#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 intsendfd(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;	*(int*)CMSG_DATA(cmsg) = fd; 	if((n=sendmsg(s, &msg, 0)) != iov.iov_len)		return -1;	return 0;} intrecvfd(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);	fd = *(int*)CMSG_DATA(cmsg);	return fd;}