/* $NetBSD: uipc_usrreq.c,v 1.28 1997/10/17 17:35:08 christos Exp $ */ /* * Copyright (c) 1997 Christopher G. Demetriou. All rights reserved. * Copyright (c) 1982, 1986, 1989, 1991, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)uipc_usrreq.c 8.3 (Berkeley) 1/4/94 */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Unix communications domain. * * TODO: * SEQPACKET, RDM * rethink name space problems * need a proper out-of-band */ struct sockaddr_un sun_noname = { sizeof(sun_noname), AF_UNIX }; ino_t unp_ino; /* prototype for fake inode numbers */ int unp_output(m, control, unp) struct mbuf *m, *control; struct unpcb *unp; { struct socket *so2; struct sockaddr_un *sun; so2 = unp->unp_conn->unp_socket; if (unp->unp_addr) sun = unp->unp_addr; else sun = &sun_noname; if (sbappendaddr(&so2->so_rcv, (struct sockaddr *)sun, m, control) == 0) { m_freem(control); m_freem(m); return (EINVAL); } else { sorwakeup(so2); return (0); } } void unp_setsockaddr(unp, nam) register struct unpcb *unp; struct mbuf *nam; { struct sockaddr_un *sun; if (unp->unp_addr) sun = unp->unp_addr; else sun = &sun_noname; nam->m_len = sun->sun_len; if (nam->m_len > MLEN) MEXTMALLOC(nam, nam->m_len, M_WAITOK); bcopy(sun, mtod(nam, caddr_t), (size_t)nam->m_len); } void unp_setpeeraddr(unp, nam) register struct unpcb *unp; struct mbuf *nam; { struct sockaddr_un *sun; if (unp->unp_conn && unp->unp_conn->unp_addr) sun = unp->unp_conn->unp_addr; else sun = &sun_noname; nam->m_len = sun->sun_len; if (nam->m_len > MLEN) MEXTMALLOC(nam, nam->m_len, M_WAITOK); bcopy(sun, mtod(nam, caddr_t), (size_t)nam->m_len); } /*ARGSUSED*/ int uipc_usrreq(so, req, m, nam, control, p) struct socket *so; int req; struct mbuf *m, *nam, *control; struct proc *p; { struct unpcb *unp = sotounpcb(so); register struct socket *so2; register int error = 0; if (req == PRU_CONTROL) return (EOPNOTSUPP); #ifdef DIAGNOSTIC if (req != PRU_SEND && req != PRU_SENDOOB && control) panic("uipc_usrreq: unexpected control mbuf"); #endif if (unp == 0 && req != PRU_ATTACH) { error = EINVAL; goto release; } switch (req) { case PRU_ATTACH: if (unp != 0) { error = EISCONN; break; } error = unp_attach(so); break; case PRU_DETACH: unp_detach(unp); break; case PRU_BIND: error = unp_bind(unp, nam, p); break; case PRU_LISTEN: if (unp->unp_vnode == 0) error = EINVAL; break; case PRU_CONNECT: error = unp_connect(so, nam, p); break; case PRU_CONNECT2: error = unp_connect2(so, (struct socket *)nam); break; case PRU_DISCONNECT: unp_disconnect(unp); break; case PRU_ACCEPT: unp_setpeeraddr(unp, nam); break; case PRU_SHUTDOWN: socantsendmore(so); unp_shutdown(unp); break; case PRU_RCVD: switch (so->so_type) { case SOCK_DGRAM: panic("uipc 1"); /*NOTREACHED*/ case SOCK_STREAM: #define rcv (&so->so_rcv) #define snd (&so2->so_snd) if (unp->unp_conn == 0) break; so2 = unp->unp_conn->unp_socket; /* * Adjust backpressure on sender * and wakeup any waiting to write. */ snd->sb_mbmax += unp->unp_mbcnt - rcv->sb_mbcnt; unp->unp_mbcnt = rcv->sb_mbcnt; snd->sb_hiwat += unp->unp_cc - rcv->sb_cc; unp->unp_cc = rcv->sb_cc; sowwakeup(so2); #undef snd #undef rcv break; default: panic("uipc 2"); } break; case PRU_SEND: if (control && (error = unp_internalize(control, p))) break; switch (so->so_type) { case SOCK_DGRAM: { if (nam) { if ((so->so_state & SS_ISCONNECTED) != 0) { error = EISCONN; goto die; } error = unp_connect(so, nam, p); if (error) { die: m_freem(control); m_freem(m); break; } } else { if ((so->so_state & SS_ISCONNECTED) == 0) { error = ENOTCONN; goto die; } } error = unp_output(m, control, unp); if (nam) unp_disconnect(unp); break; } case SOCK_STREAM: #define rcv (&so2->so_rcv) #define snd (&so->so_snd) if (unp->unp_conn == 0) panic("uipc 3"); so2 = unp->unp_conn->unp_socket; /* * Send to paired receive port, and then reduce * send buffer hiwater marks to maintain backpressure. * Wake up readers. */ if (control) { if (sbappendcontrol(rcv, m, control) == 0) m_freem(control); } else sbappend(rcv, m); snd->sb_mbmax -= rcv->sb_mbcnt - unp->unp_conn->unp_mbcnt; unp->unp_conn->unp_mbcnt = rcv->sb_mbcnt; snd->sb_hiwat -= rcv->sb_cc - unp->unp_conn->unp_cc; unp->unp_conn->unp_cc = rcv->sb_cc; sorwakeup(so2); #undef snd #undef rcv break; default: panic("uipc 4"); } break; case PRU_ABORT: unp_drop(unp, ECONNABORTED); break; case PRU_SENSE: ((struct stat *) m)->st_blksize = so->so_snd.sb_hiwat; if (so->so_type == SOCK_STREAM && unp->unp_conn != 0) { so2 = unp->unp_conn->unp_socket; ((struct stat *) m)->st_blksize += so2->so_rcv.sb_cc; } ((struct stat *) m)->st_dev = NODEV; if (unp->unp_ino == 0) unp->unp_ino = unp_ino++; ((struct stat *) m)->st_atimespec = ((struct stat *) m)->st_mtimespec = ((struct stat *) m)->st_ctimespec = unp->unp_ctime; ((struct stat *) m)->st_ino = unp->unp_ino; return (0); case PRU_RCVOOB: error = EOPNOTSUPP; break; case PRU_SENDOOB: m_freem(control); m_freem(m); error = EOPNOTSUPP; break; case PRU_SOCKADDR: unp_setsockaddr(unp, nam); break; case PRU_PEERADDR: unp_setpeeraddr(unp, nam); break; default: panic("piusrreq"); } release: return (error); } /* * Both send and receive buffers are allocated PIPSIZ bytes of buffering * for stream sockets, although the total for sender and receiver is * actually only PIPSIZ. * Datagram sockets really use the sendspace as the maximum datagram size, * and don't really want to reserve the sendspace. Their recvspace should * be large enough for at least one max-size datagram plus address. */ #define PIPSIZ 4096 u_long unpst_sendspace = PIPSIZ; u_long unpst_recvspace = PIPSIZ; u_long unpdg_sendspace = 2*1024; /* really max datagram size */ u_long unpdg_recvspace = 4*1024; int unp_rights; /* file descriptors in flight */ int unp_attach(so) struct socket *so; { register struct unpcb *unp; struct timeval tv; int error; if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) { switch (so->so_type) { case SOCK_STREAM: error = soreserve(so, unpst_sendspace, unpst_recvspace); break; case SOCK_DGRAM: error = soreserve(so, unpdg_sendspace, unpdg_recvspace); break; default: panic("unp_attach"); } if (error) return (error); } unp = malloc(sizeof(*unp), M_PCB, M_NOWAIT); if (unp == NULL) return (ENOBUFS); bzero((caddr_t)unp, sizeof(*unp)); unp->unp_socket = so; so->so_pcb = unp; microtime(&tv); TIMEVAL_TO_TIMESPEC(&tv, &unp->unp_ctime); return (0); } void unp_detach(unp) register struct unpcb *unp; { if (unp->unp_vnode) { unp->unp_vnode->v_socket = 0; vrele(unp->unp_vnode); unp->unp_vnode = 0; } if (unp->unp_conn) unp_disconnect(unp); while (unp->unp_refs) unp_drop(unp->unp_refs, ECONNRESET); soisdisconnected(unp->unp_socket); unp->unp_socket->so_pcb = 0; if (unp->unp_addr) free(unp->unp_addr, M_SONAME); if (unp_rights) { /* * Normally the receive buffer is flushed later, * in sofree, but if our receive buffer holds references * to descriptors that are now garbage, we will dispose * of those descriptor references after the garbage collector * gets them (resulting in a "panic: closef: count < 0"). */ sorflush(unp->unp_socket); free(unp, M_PCB); unp_gc(); } else free(unp, M_PCB); } int unp_bind(unp, nam, p) struct unpcb *unp; struct mbuf *nam; struct proc *p; { struct sockaddr_un *sun; register struct vnode *vp; struct vattr vattr; size_t addrlen; int error; struct nameidata nd; if (unp->unp_vnode != 0) return (EINVAL); /* * Allocate the new sockaddr. We have to allocate one * extra byte so that we can ensure that the pathname * is nul-terminated. */ addrlen = nam->m_len + 1; sun = malloc(addrlen, M_SONAME, M_WAITOK); m_copydata(nam, 0, nam->m_len, (caddr_t)sun); *(((char *)sun) + nam->m_len) = '\0'; NDINIT(&nd, CREATE, FOLLOW | LOCKPARENT, UIO_SYSSPACE, sun->sun_path, p); /* SHOULD BE ABLE TO ADOPT EXISTING AND wakeup() ALA FIFO's */ if ((error = namei(&nd)) != 0) goto bad; vp = nd.ni_vp; if (vp != NULL) { VOP_ABORTOP(nd.ni_dvp, &nd.ni_cnd); if (nd.ni_dvp == vp) vrele(nd.ni_dvp); else vput(nd.ni_dvp); vrele(vp); error = EADDRINUSE; goto bad; } VATTR_NULL(&vattr); vattr.va_type = VSOCK; vattr.va_mode = ACCESSPERMS; VOP_LEASE(nd.ni_dvp, p, p->p_ucred, LEASE_WRITE); error = VOP_CREATE(nd.ni_dvp, &nd.ni_vp, &nd.ni_cnd, &vattr); if (error) goto bad; vp = nd.ni_vp; vp->v_socket = unp->unp_socket; unp->unp_vnode = vp; unp->unp_addrlen = addrlen; unp->unp_addr = sun; VOP_UNLOCK(vp); return (0); bad: free(sun, M_SONAME); return (error); } int unp_connect(so, nam, p) struct socket *so; struct mbuf *nam; struct proc *p; { register struct sockaddr_un *sun; register struct vnode *vp; register struct socket *so2, *so3; struct unpcb *unp2, *unp3; size_t addrlen; int error; struct nameidata nd; /* * Allocate a temporary sockaddr. We have to allocate one extra * byte so that we can ensure that the pathname is nul-terminated. * When we establish the connection, we copy the other PCB's * sockaddr to our own. */ addrlen = nam->m_len + 1; sun = malloc(addrlen, M_SONAME, M_WAITOK); m_copydata(nam, 0, nam->m_len, (caddr_t)sun); *(((char *)sun) + nam->m_len) = '\0'; NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, sun->sun_path, p); if ((error = namei(&nd)) != 0) goto bad2; vp = nd.ni_vp; if (vp->v_type != VSOCK) { error = ENOTSOCK; goto bad; } if ((error = VOP_ACCESS(vp, VWRITE, p->p_ucred, p)) != 0) goto bad; so2 = vp->v_socket; if (so2 == 0) { error = ECONNREFUSED; goto bad; } if (so->so_type != so2->so_type) { error = EPROTOTYPE; goto bad; } if (so->so_proto->pr_flags & PR_CONNREQUIRED) { if ((so2->so_options & SO_ACCEPTCONN) == 0 || (so3 = sonewconn(so2, 0)) == 0) { error = ECONNREFUSED; goto bad; } unp2 = sotounpcb(so2); unp3 = sotounpcb(so3); if (unp2->unp_addr) { unp3->unp_addr = malloc(unp2->unp_addrlen, M_SONAME, M_WAITOK); bcopy(unp2->unp_addr, unp3->unp_addr, unp2->unp_addrlen); unp3->unp_addrlen = unp2->unp_addrlen; } so2 = so3; } error = unp_connect2(so, so2); bad: vput(vp); bad2: free(sun, M_SONAME); return (error); } int unp_connect2(so, so2) register struct socket *so; register struct socket *so2; { register struct unpcb *unp = sotounpcb(so); register struct unpcb *unp2; if (so2->so_type != so->so_type) return (EPROTOTYPE); unp2 = sotounpcb(so2); unp->unp_conn = unp2; switch (so->so_type) { case SOCK_DGRAM: unp->unp_nextref = unp2->unp_refs; unp2->unp_refs = unp; soisconnected(so); break; case SOCK_STREAM: unp2->unp_conn = unp; soisconnected(so); soisconnected(so2); break; default: panic("unp_connect2"); } return (0); } void unp_disconnect(unp) struct unpcb *unp; { register struct unpcb *unp2 = unp->unp_conn; if (unp2 == 0) return; unp->unp_conn = 0; switch (unp->unp_socket->so_type) { case SOCK_DGRAM: if (unp2->unp_refs == unp) unp2->unp_refs = unp->unp_nextref; else { unp2 = unp2->unp_refs; for (;;) { if (unp2 == 0) panic("unp_disconnect"); if (unp2->unp_nextref == unp) break; unp2 = unp2->unp_nextref; } unp2->unp_nextref = unp->unp_nextref; } unp->unp_nextref = 0; unp->unp_socket->so_state &= ~SS_ISCONNECTED; break; case SOCK_STREAM: soisdisconnected(unp->unp_socket); unp2->unp_conn = 0; soisdisconnected(unp2->unp_socket); break; } } #ifdef notdef unp_abort(unp) struct unpcb *unp; { unp_detach(unp); } #endif void unp_shutdown(unp) struct unpcb *unp; { struct socket *so; if (unp->unp_socket->so_type == SOCK_STREAM && unp->unp_conn && (so = unp->unp_conn->unp_socket)) socantrcvmore(so); } void unp_drop(unp, errno) struct unpcb *unp; int errno; { struct socket *so = unp->unp_socket; so->so_error = errno; unp_disconnect(unp); if (so->so_head) { so->so_pcb = 0; sofree(so); if (unp->unp_addr) free(unp->unp_addr, M_SONAME); free(unp, M_PCB); } } #ifdef notdef unp_drain() { } #endif int unp_externalize(rights) struct mbuf *rights; { struct proc *p = curproc; /* XXX */ register struct cmsghdr *cm = mtod(rights, struct cmsghdr *); register int i, *fdp = (int *)(cm + 1); register struct file **rp = (struct file **)ALIGN(cm + 1); register struct file *fp; int nfds = (cm->cmsg_len - ALIGN(sizeof(*cm))) / sizeof (struct file *); int f; /* Make sure that the recipient has space */ if (!fdavail(p, nfds)) { for (i = 0; i < nfds; i++) { fp = *rp; unp_discard(fp); *rp++ = 0; } return (EMSGSIZE); } /* * Add file to the recipient's open file table, converting them * to integer file descriptors as we go. Done in forward order * because an integer will always come in the same place or before * its corresponding struct file pointer. */ for (i = 0; i < nfds; i++) { if (fdalloc(p, 0, &f)) panic("unp_externalize"); fp = *rp; p->p_fd->fd_ofiles[f] = fp; fp->f_msgcount--; unp_rights--; *fdp++ = f; } /* * Adjust length, in case of transition from large struct file * pointers to ints. */ cm->cmsg_len = sizeof(*cm) + (nfds * sizeof(int)); rights->m_len = cm->cmsg_len; return (0); } int unp_internalize(control, p) struct mbuf *control; struct proc *p; { struct filedesc *fdescp = p->p_fd; register struct cmsghdr *cm = mtod(control, struct cmsghdr *); register struct file **rp; register struct file *fp; register int i, fd, *fdp; int nfds; u_int neededspace; /* Sanity check the control message header */ if (cm->cmsg_type != SCM_RIGHTS || cm->cmsg_level != SOL_SOCKET || cm->cmsg_len != control->m_len) return (EINVAL); /* Verify that the file descriptors are valid */ nfds = (cm->cmsg_len - sizeof (*cm)) / sizeof (int); fdp = (int *)(cm + 1); for (i = 0; i < nfds; i++) { fd = *fdp++; if ((unsigned)fd >= fdescp->fd_nfiles || fdescp->fd_ofiles[fd] == NULL) return (EBADF); } /* Make sure we have room for the struct file pointers */ morespace: neededspace = (ALIGN(sizeof (*cm)) + nfds * sizeof (struct file *)) - control->m_len; if (neededspace > M_TRAILINGSPACE(control)) { /* if we already have a cluster, the message is just too big */ if (control->m_flags & M_EXT) return (E2BIG); /* allocate a cluster and try again */ MCLGET(control, M_WAIT); if ((control->m_flags & M_EXT) == 0) return (ENOBUFS); /* allocation failed */ /* copy the data to the cluster */ bcopy(cm, mtod(control, char *), cm->cmsg_len); cm = mtod(control, struct cmsghdr *); goto morespace; } /* adjust message & mbuf to note amount of space actually used. */ cm->cmsg_len += neededspace; control->m_len = cm->cmsg_len; /* * Transform the file descriptors into struct file pointers, in * reverse order so that if pointers are bigger than ints, the * int won't get until we're done. */ fdp = ((int *)(cm + 1)) + nfds - 1; rp = ((struct file **)ALIGN(cm + 1)) + nfds - 1; for (i = 0; i < nfds; i++) { fp = fdescp->fd_ofiles[*fdp--]; *rp-- = fp; fp->f_count++; fp->f_msgcount++; unp_rights++; } return (0); } int unp_defer, unp_gcing; extern struct domain unixdomain; void unp_gc() { register struct file *fp, *nextfp; register struct socket *so; struct file **extra_ref, **fpp; int nunref, i; if (unp_gcing) return; unp_gcing = 1; unp_defer = 0; for (fp = filehead.lh_first; fp != 0; fp = fp->f_list.le_next) fp->f_flag &= ~(FMARK|FDEFER); do { for (fp = filehead.lh_first; fp != 0; fp = fp->f_list.le_next) { if (fp->f_count == 0) continue; if (fp->f_flag & FDEFER) { fp->f_flag &= ~FDEFER; unp_defer--; } else { if (fp->f_flag & FMARK) continue; if (fp->f_count == fp->f_msgcount) continue; fp->f_flag |= FMARK; } if (fp->f_type != DTYPE_SOCKET || (so = (struct socket *)fp->f_data) == 0) continue; if (so->so_proto->pr_domain != &unixdomain || (so->so_proto->pr_flags&PR_RIGHTS) == 0) continue; #ifdef notdef if (so->so_rcv.sb_flags & SB_LOCK) { /* * This is problematical; it's not clear * we need to wait for the sockbuf to be * unlocked (on a uniprocessor, at least), * and it's also not clear what to do * if sbwait returns an error due to receipt * of a signal. If sbwait does return * an error, we'll go into an infinite * loop. Delete all of this for now. */ (void) sbwait(&so->so_rcv); goto restart; } #endif unp_scan(so->so_rcv.sb_mb, unp_mark); } } while (unp_defer); /* * We grab an extra reference to each of the file table entries * that are not otherwise accessible and then free the rights * that are stored in messages on them. * * The bug in the orginal code is a little tricky, so I'll describe * what's wrong with it here. * * It is incorrect to simply unp_discard each entry for f_msgcount * times -- consider the case of sockets A and B that contain * references to each other. On a last close of some other socket, * we trigger a gc since the number of outstanding rights (unp_rights) * is non-zero. If during the sweep phase the gc code un_discards, * we end up doing a (full) closef on the descriptor. A closef on A * results in the following chain. Closef calls soo_close, which * calls soclose. Soclose calls first (through the switch * uipc_usrreq) unp_detach, which re-invokes unp_gc. Unp_gc simply * returns because the previous instance had set unp_gcing, and * we return all the way back to soclose, which marks the socket * with SS_NOFDREF, and then calls sofree. Sofree calls sorflush * to free up the rights that are queued in messages on the socket A, * i.e., the reference on B. The sorflush calls via the dom_dispose * switch unp_dispose, which unp_scans with unp_discard. This second * instance of unp_discard just calls closef on B. * * Well, a similar chain occurs on B, resulting in a sorflush on B, * which results in another closef on A. Unfortunately, A is already * being closed, and the descriptor has already been marked with * SS_NOFDREF, and soclose panics at this point. * * Here, we first take an extra reference to each inaccessible * descriptor. Then, we call sorflush ourself, since we know * it is a Unix domain socket anyhow. After we destroy all the * rights carried in messages, we do a last closef to get rid * of our extra reference. This is the last close, and the * unp_detach etc will shut down the socket. * * 91/09/19, bsy@cs.cmu.edu */ extra_ref = malloc(nfiles * sizeof(struct file *), M_FILE, M_WAITOK); for (nunref = 0, fp = filehead.lh_first, fpp = extra_ref; fp != 0; fp = nextfp) { nextfp = fp->f_list.le_next; if (fp->f_count == 0) continue; if (fp->f_count == fp->f_msgcount && !(fp->f_flag & FMARK)) { *fpp++ = fp; nunref++; fp->f_count++; } } for (i = nunref, fpp = extra_ref; --i >= 0; ++fpp) sorflush((struct socket *)(*fpp)->f_data); for (i = nunref, fpp = extra_ref; --i >= 0; ++fpp) (void) closef(*fpp, (struct proc *)0); free((caddr_t)extra_ref, M_FILE); unp_gcing = 0; } void unp_dispose(m) struct mbuf *m; { if (m) unp_scan(m, unp_discard); } void unp_scan(m0, op) register struct mbuf *m0; void (*op) __P((struct file *)); { register struct mbuf *m; register struct file **rp; register struct cmsghdr *cm; register int i; int qfds; while (m0) { for (m = m0; m; m = m->m_next) if (m->m_type == MT_CONTROL && m->m_len >= sizeof(*cm)) { cm = mtod(m, struct cmsghdr *); if (cm->cmsg_level != SOL_SOCKET || cm->cmsg_type != SCM_RIGHTS) continue; qfds = (cm->cmsg_len - sizeof *cm) / sizeof (struct file *); rp = (struct file **)(cm + 1); for (i = 0; i < qfds; i++) (*op)(*rp++); break; /* XXX, but saves time */ } m0 = m0->m_act; } } void unp_mark(fp) struct file *fp; { if (fp->f_flag & FMARK) return; unp_defer++; fp->f_flag |= (FMARK|FDEFER); } void unp_discard(fp) struct file *fp; { fp->f_msgcount--; unp_rights--; (void) closef(fp, (struct proc *)0); }