sys/vfs/fifofs/fifo_vnops.c

   1 /*
   2  * Copyright (c) 1990, 1993, 1995
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33 /*
  34  * Filesystem FIFO type ops.  All entry points are MPSAFE.  We primarily
  35  * use v_token to interlock operations.
  36  */
  37 #include <sys/param.h>
  38 #include <sys/systm.h>
  39 #include <sys/unistd.h>
  40 #include <sys/kernel.h>
  41 #include <sys/lock.h>
  42 #include <sys/malloc.h>
  43 #include <sys/thread2.h>
  44 #include <sys/vnode.h>
  45 #include <sys/socket.h>
  46 #include <sys/socketvar.h>
  47 #include <sys/filio.h>
  48 #include <sys/fcntl.h>
  49 #include <sys/file.h>
  50 #include <sys/event.h>
  51 #include <sys/poll.h>
  52 #include <sys/un.h>
  53
  54 #include <sys/thread2.h>
  55
  56 #include "fifo.h"
  57
  58 /*
  59  * This structure is associated with the FIFO vnode and stores
  60  * the state associated with the FIFO.
  61  */
  62 struct fifoinfo {
  63         struct socket   *fi_readsock;
  64         struct socket   *fi_writesock;
  65         long            fi_readers;
  66         long            fi_writers;
  67 };
  68
  69 static int      fifo_badop (void);
  70 static int      fifo_print (struct vop_print_args *);
  71 static int      fifo_lookup (struct vop_old_lookup_args *);
  72 static int      fifo_open (struct vop_open_args *);
  73 static int      fifo_close (struct vop_close_args *);
  74 static int      fifo_read (struct vop_read_args *);
  75 static int      fifo_write (struct vop_write_args *);
  76 static int      fifo_ioctl (struct vop_ioctl_args *);
  77 static int      fifo_poll (struct vop_poll_args *);
  78 static int      fifo_kqfilter (struct vop_kqfilter_args *);
  79 static int      fifo_inactive (struct  vop_inactive_args *);
  80 static int      fifo_bmap (struct vop_bmap_args *);
  81 static int      fifo_pathconf (struct vop_pathconf_args *);
  82 static int      fifo_advlock (struct vop_advlock_args *);
  83
  84 static void     filt_fifordetach(struct knote *kn);
  85 static int      filt_fiforead(struct knote *kn, long hint);
  86 static void     filt_fifowdetach(struct knote *kn);
  87 static int      filt_fifowrite(struct knote *kn, long hint);
  88
  89 static struct filterops fiforead_filtops =
  90         { 1, NULL, filt_fifordetach, filt_fiforead };
  91 static struct filterops fifowrite_filtops =
  92         { 1, NULL, filt_fifowdetach, filt_fifowrite };
  93
  94 struct vop_ops fifo_vnode_vops = {
  95         .vop_default =          vop_defaultop,
  96         .vop_access =           (void *)vop_ebadf,
  97         .vop_advlock =          fifo_advlock,
  98         .vop_bmap =             fifo_bmap,
  99         .vop_close =            fifo_close,
 100         .vop_old_create =       (void *)fifo_badop,
 101         .vop_getattr =          (void *)vop_ebadf,
 102         .vop_inactive =         fifo_inactive,
 103         .vop_ioctl =            fifo_ioctl,
 104         .vop_kqfilter =         fifo_kqfilter,
 105         .vop_old_link =         (void *)fifo_badop,
 106         .vop_old_lookup =       fifo_lookup,
 107         .vop_old_mkdir =        (void *)fifo_badop,
 108         .vop_old_mknod =        (void *)fifo_badop,
 109         .vop_open =             fifo_open,
 110         .vop_pathconf =         fifo_pathconf,
 111         .vop_poll =             fifo_poll,
 112         .vop_print =            fifo_print,
 113         .vop_read =             fifo_read,
 114         .vop_readdir =          (void *)fifo_badop,
 115         .vop_readlink =         (void *)fifo_badop,
 116         .vop_reallocblks =      (void *)fifo_badop,
 117         .vop_reclaim =          (void *)vop_null,
 118         .vop_old_remove =       (void *)fifo_badop,
 119         .vop_old_rename =       (void *)fifo_badop,
 120         .vop_old_rmdir =        (void *)fifo_badop,
 121         .vop_setattr =          (void *)vop_ebadf,
 122         .vop_old_symlink =      (void *)fifo_badop,
 123         .vop_write =            fifo_write
 124 };
 125
 126 VNODEOP_SET(fifo_vnode_vops);
 127
 128 static MALLOC_DEFINE(M_FIFOINFO, "Fifo info", "Fifo info entries");
 129
 130 /*
 131  * fifo_vnoperate()
 132  */
 133 int
 134 fifo_vnoperate(struct vop_generic_args *ap)
 135 {
 136         return (VOCALL(&fifo_vnode_vops, ap));
 137 }
 138
 139 /*
 140  * Trivial lookup routine that always fails.
 141  *
 142  * fifo_lookup(struct vnode *a_dvp, struct vnode **a_vpp,
 143  *             struct componentname *a_cnp)
 144  */
 145 /* ARGSUSED */
 146 static int
 147 fifo_lookup(struct vop_old_lookup_args *ap)
 148 {
 149         *ap->a_vpp = NULL;
 150         return (ENOTDIR);
 151 }
 152
 153 /*
 154  * Open called to set up a new instance of a fifo or
 155  * to find an active instance of a fifo.
 156  *
 157  * fifo_open(struct vnode *a_vp, int a_mode, struct ucred *a_cred,
 158  *           struct file *a_fp)
 159  */
 160 /* ARGSUSED */
 161 static int
 162 fifo_open(struct vop_open_args *ap)
 163 {
 164         struct thread *td = curthread;
 165         struct vnode *vp = ap->a_vp;
 166         struct fifoinfo *fip;
 167         struct socket *rso, *wso;
 168         lwkt_tokref     vlock;
 169         int error;
 170
 171         lwkt_gettoken(&vlock, &vp->v_token);
 172         if ((fip = vp->v_fifoinfo) == NULL) {
 173                 MALLOC(fip, struct fifoinfo *, sizeof(*fip), M_FIFOINFO, M_WAITOK);
 174                 vp->v_fifoinfo = fip;
 175                 error = socreate(AF_LOCAL, &rso, SOCK_STREAM, 0, td);
 176                 if (error) {
 177                         kfree(fip, M_FIFOINFO);
 178                         vp->v_fifoinfo = NULL;
 179                         goto done;
 180                 }
 181                 fip->fi_readsock = rso;
 182                 error = socreate(AF_LOCAL, &wso, SOCK_STREAM, 0, td);
 183                 if (error) {
 184                         soclose(rso, FNONBLOCK);
 185                         kfree(fip, M_FIFOINFO);
 186                         vp->v_fifoinfo = NULL;
 187                         goto done;
 188                 }
 189                 fip->fi_writesock = wso;
 190                 error = unp_connect2(wso, rso);
 191                 if (error) {
 192                         soclose(wso, FNONBLOCK);
 193                         soclose(rso, FNONBLOCK);
 194                         kfree(fip, M_FIFOINFO);
 195                         vp->v_fifoinfo = NULL;
 196                         goto done;
 197                 }
 198                 fip->fi_readers = fip->fi_writers = 0;
 199                 wso->so_snd.ssb_lowat = PIPE_BUF;
 200                 rso->so_state |= SS_CANTRCVMORE;
 201         }
 202         if (ap->a_mode & FREAD) {
 203                 fip->fi_readers++;
 204                 if (fip->fi_readers == 1) {
 205                         fip->fi_writesock->so_state &= ~SS_CANTSENDMORE;
 206                         if (fip->fi_writers > 0) {
 207                                 wakeup((caddr_t)&fip->fi_writers);
 208                                 sowwakeup(fip->fi_writesock);
 209                         }
 210                 }
 211         }
 212         if (ap->a_mode & FWRITE) {
 213                 fip->fi_writers++;
 214                 if (fip->fi_writers == 1) {
 215                         fip->fi_readsock->so_state &= ~SS_CANTRCVMORE;
 216                         if (fip->fi_readers > 0) {
 217                                 wakeup((caddr_t)&fip->fi_readers);
 218                                 sorwakeup(fip->fi_writesock);
 219                         }
 220                 }
 221         }
 222         if ((ap->a_mode & FREAD) && (ap->a_mode & O_NONBLOCK) == 0) {
 223                 if (fip->fi_writers == 0) {
 224                         vn_unlock(vp);
 225                         error = tsleep((caddr_t)&fip->fi_readers,
 226                             PCATCH, "fifoor", 0);
 227                         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 228                         if (error)
 229                                 goto bad;
 230                         /*
 231                          * We must have got woken up because we had a writer.
 232                          * That (and not still having one) is the condition
 233                          * that we must wait for.
 234                          */
 235                 }
 236         }
 237         if (ap->a_mode & FWRITE) {
 238                 if (ap->a_mode & O_NONBLOCK) {
 239                         if (fip->fi_readers == 0) {
 240                                 error = ENXIO;
 241                                 goto bad;
 242                         }
 243                 } else {
 244                         if (fip->fi_readers == 0) {
 245                                 vn_unlock(vp);
 246                                 error = tsleep((caddr_t)&fip->fi_writers,
 247                                     PCATCH, "fifoow", 0);
 248                                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 249                                 if (error)
 250                                         goto bad;
 251                                 /*
 252                                  * We must have got woken up because we had
 253                                  * a reader.  That (and not still having one)
 254                                  * is the condition that we must wait for.
 255                                  */
 256                         }
 257                 }
 258         }
 259         vsetflags(vp, VNOTSEEKABLE);
 260         error = vop_stdopen(ap);
 261         lwkt_reltoken(&vlock);
 262         return (error);
 263 bad:
 264         vop_stdopen(ap);        /* bump opencount/writecount as appropriate */
 265         VOP_CLOSE(vp, ap->a_mode);
 266 done:
 267         lwkt_reltoken(&vlock);
 268         return (error);
 269 }
 270
 271 /*
 272  * Vnode op for read
 273  *
 274  * fifo_read(struct vnode *a_vp, struct uio *a_uio, int a_ioflag,
 275  *           struct ucred *a_cred)
 276  */
 277 /* ARGSUSED */
 278 static int
 279 fifo_read(struct vop_read_args *ap)
 280 {
 281         struct uio *uio = ap->a_uio;
 282         struct socket *rso = ap->a_vp->v_fifoinfo->fi_readsock;
 283         int error, startresid;
 284         lwkt_tokref vlock;
 285         int flags;
 286
 287 #ifdef DIAGNOSTIC
 288         if (uio->uio_rw != UIO_READ)
 289                 panic("fifo_read mode");
 290 #endif
 291         if (uio->uio_resid == 0)
 292                 return (0);
 293         if (ap->a_ioflag & IO_NDELAY)
 294                 flags = MSG_FNONBLOCKING;
 295         else
 296                 flags = 0;
 297         startresid = uio->uio_resid;
 298         vn_unlock(ap->a_vp);
 299         lwkt_gettoken(&vlock, &ap->a_vp->v_token);
 300         error = soreceive(rso, NULL, uio, NULL, NULL, &flags);
 301         lwkt_reltoken(&vlock);
 302         vn_lock(ap->a_vp, LK_EXCLUSIVE | LK_RETRY);
 303         return (error);
 304 }
 305
 306 /*
 307  * Vnode op for write
 308  *
 309  * fifo_write(struct vnode *a_vp, struct uio *a_uio, int a_ioflag,
 310  *            struct ucred *a_cred)
 311  */
 312 /* ARGSUSED */
 313 static int
 314 fifo_write(struct vop_write_args *ap)
 315 {
 316         struct socket *wso = ap->a_vp->v_fifoinfo->fi_writesock;
 317         struct thread *td = ap->a_uio->uio_td;
 318         lwkt_tokref vlock;
 319         int error;
 320         int flags;
 321
 322 #ifdef DIAGNOSTIC
 323         if (ap->a_uio->uio_rw != UIO_WRITE)
 324                 panic("fifo_write mode");
 325 #endif
 326         if (ap->a_ioflag & IO_NDELAY)
 327                 flags = MSG_FNONBLOCKING;
 328         else
 329                 flags = 0;
 330         vn_unlock(ap->a_vp);
 331         lwkt_gettoken(&vlock, &ap->a_vp->v_token);
 332         error = sosend(wso, NULL, ap->a_uio, 0, NULL, flags, td);
 333         lwkt_reltoken(&vlock);
 334         vn_lock(ap->a_vp, LK_EXCLUSIVE | LK_RETRY);
 335         return (error);
 336 }
 337
 338 /*
 339  * Device ioctl operation.
 340  *
 341  * fifo_ioctl(struct vnode *a_vp, int a_command, caddr_t a_data, int a_fflag,
 342  *            struct ucred *a_cred, struct sysmsg *a_sysmsg)
 343  */
 344 /* ARGSUSED */
 345 static int
 346 fifo_ioctl(struct vop_ioctl_args *ap)
 347 {
 348         struct file filetmp;    /* Local */
 349         lwkt_tokref vlock;
 350         int error;
 351
 352         if (ap->a_fflag & FREAD) {
 353                 filetmp.f_data = ap->a_vp->v_fifoinfo->fi_readsock;
 354                 lwkt_gettoken(&vlock, &ap->a_vp->v_token);
 355                 error = soo_ioctl(&filetmp, ap->a_command, ap->a_data,
 356                                   ap->a_cred, ap->a_sysmsg);
 357                 lwkt_reltoken(&vlock);
 358                 if (error)
 359                         return (error);
 360         }
 361         if (ap->a_fflag & FWRITE) {
 362                 filetmp.f_data = ap->a_vp->v_fifoinfo->fi_writesock;
 363                 lwkt_gettoken(&vlock, &ap->a_vp->v_token);
 364                 error = soo_ioctl(&filetmp, ap->a_command, ap->a_data,
 365                                   ap->a_cred, ap->a_sysmsg);
 366                 lwkt_reltoken(&vlock);
 367                 if (error)
 368                         return (error);
 369         }
 370         return (0);
 371 }
 372
 373 /*
 374  * fifo_kqfilter(struct vnode *a_vp, struct knote *a_kn)
 375  */
 376 /* ARGSUSED */
 377 static int
 378 fifo_kqfilter(struct vop_kqfilter_args *ap)
 379 {
 380         struct vnode *vp = ap->a_vp;
 381         struct fifoinfo *fi = vp->v_fifoinfo;
 382         struct socket *so;
 383         struct signalsockbuf *ssb;
 384         lwkt_tokref vlock;
 385
 386         lwkt_gettoken(&vlock, &vp->v_token);
 387
 388         switch (ap->a_kn->kn_filter) {
 389         case EVFILT_READ:
 390                 ap->a_kn->kn_fop = &fiforead_filtops;
 391                 so = fi->fi_readsock;
 392                 ssb = &so->so_rcv;
 393                 break;
 394         case EVFILT_WRITE:
 395                 ap->a_kn->kn_fop = &fifowrite_filtops;
 396                 so = fi->fi_writesock;
 397                 ssb = &so->so_snd;
 398                 break;
 399         default:
 400                 lwkt_reltoken(&vlock);
 401                 return (1);
 402         }
 403
 404         ap->a_kn->kn_hook = (caddr_t)vp;
 405         ssb_insert_knote(ssb, ap->a_kn);
 406
 407         lwkt_reltoken(&vlock);
 408         return (0);
 409 }
 410
 411 static void
 412 filt_fifordetach(struct knote *kn)
 413 {
 414         struct vnode *vp = (void *)kn->kn_hook;
 415         struct socket *so = vp->v_fifoinfo->fi_readsock;
 416         lwkt_tokref vlock;
 417
 418         lwkt_gettoken(&vlock, &vp->v_token);
 419         ssb_remove_knote(&so->so_rcv, kn);
 420         lwkt_reltoken(&vlock);
 421 }
 422
 423 static int
 424 filt_fiforead(struct knote *kn, long hint)
 425 {
 426         struct vnode *vp = (void *)kn->kn_hook;
 427         struct socket *so = vp->v_fifoinfo->fi_readsock;
 428         lwkt_tokref vlock;
 429
 430         lwkt_gettoken(&vlock, &vp->v_token);
 431         kn->kn_data = so->so_rcv.ssb_cc;
 432         if (so->so_state & SS_CANTRCVMORE) {
 433                 kn->kn_flags |= EV_EOF;
 434                 lwkt_reltoken(&vlock);
 435                 return (1);
 436         }
 437         kn->kn_flags &= ~EV_EOF;
 438         lwkt_reltoken(&vlock);
 439         return (kn->kn_data > 0);
 440 }
 441
 442 static void
 443 filt_fifowdetach(struct knote *kn)
 444 {
 445         struct vnode *vp = (void *)kn->kn_hook;
 446         struct socket *so = vp->v_fifoinfo->fi_writesock;
 447         lwkt_tokref vlock;
 448
 449         lwkt_gettoken(&vlock, &vp->v_token);
 450         ssb_remove_knote(&so->so_snd, kn);
 451         lwkt_reltoken(&vlock);
 452 }
 453
 454 static int
 455 filt_fifowrite(struct knote *kn, long hint)
 456 {
 457         struct vnode *vp = (void *)kn->kn_hook;
 458         struct socket *so = vp->v_fifoinfo->fi_writesock;
 459         lwkt_tokref vlock;
 460
 461         lwkt_gettoken(&vlock, &vp->v_token);
 462         kn->kn_data = ssb_space(&so->so_snd);
 463         if (so->so_state & SS_CANTSENDMORE) {
 464                 kn->kn_flags |= EV_EOF;
 465                 lwkt_reltoken(&vlock);
 466                 return (1);
 467         }
 468         kn->kn_flags &= ~EV_EOF;
 469         lwkt_reltoken(&vlock);
 470         return (kn->kn_data >= so->so_snd.ssb_lowat);
 471 }
 472
 473 /*
 474  * fifo_poll(struct vnode *a_vp, int a_events, struct ucred *a_cred)
 475  */
 476 /* ARGSUSED */
 477 static int
 478 fifo_poll(struct vop_poll_args *ap)
 479 {
 480         struct file filetmp;
 481         int events, revents = 0;
 482         lwkt_tokref vlock;
 483
 484         lwkt_gettoken(&vlock, &ap->a_vp->v_token);
 485         events = ap->a_events &
 486                 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND);
 487         if (events) {
 488                 /*
 489                  * If POLLIN or POLLRDNORM is requested and POLLINIGNEOF is
 490                  * not, then convert the first two to the last one.  This
 491                  * tells the socket poll function to ignore EOF so that we
 492                  * block if there is no writer (and no data).  Callers can
 493                  * set POLLINIGNEOF to get non-blocking behavior.
 494                  */
 495                 if (events & (POLLIN | POLLRDNORM) &&
 496                         !(events & POLLINIGNEOF)) {
 497                         events &= ~(POLLIN | POLLRDNORM);
 498                         events |= POLLINIGNEOF;
 499                 }
 500
 501                 filetmp.f_data = ap->a_vp->v_fifoinfo->fi_readsock;
 502                 if (filetmp.f_data)
 503                         revents |= soo_poll(&filetmp, events, ap->a_cred);
 504
 505                 /* Reverse the above conversion. */
 506                 if ((revents & POLLINIGNEOF) &&
 507                         !(ap->a_events & POLLINIGNEOF)) {
 508                         revents |= (ap->a_events & (POLLIN | POLLRDNORM));
 509                         revents &= ~POLLINIGNEOF;
 510                 }
 511         }
 512         events = ap->a_events & (POLLOUT | POLLWRNORM | POLLWRBAND);
 513         if (events) {
 514                 filetmp.f_data = ap->a_vp->v_fifoinfo->fi_writesock;
 515                 if (filetmp.f_data)
 516                         revents |= soo_poll(&filetmp, events, ap->a_cred);
 517         }
 518         lwkt_reltoken(&vlock);
 519         return (revents);
 520 }
 521
 522 /*
 523  * fifo_inactive(struct vnode *a_vp)
 524  */
 525 static int
 526 fifo_inactive(struct vop_inactive_args *ap)
 527 {
 528         return (0);
 529 }
 530
 531 /*
 532  * This is a noop, simply returning what one has been given.
 533  *
 534  * fifo_bmap(struct vnode *a_vp, off_t a_loffset,
 535  *           off_t *a_doffsetp, int *a_runp, int *a_runb)
 536  */
 537 static int
 538 fifo_bmap(struct vop_bmap_args *ap)
 539 {
 540         if (ap->a_doffsetp != NULL)
 541                 *ap->a_doffsetp = ap->a_loffset;
 542         if (ap->a_runp != NULL)
 543                 *ap->a_runp = 0;
 544         if (ap->a_runb != NULL)
 545                 *ap->a_runb = 0;
 546         return (0);
 547 }
 548
 549 /*
 550  * Device close routine
 551  *
 552  * fifo_close(struct vnode *a_vp, int a_fflag)
 553  */
 554 /* ARGSUSED */
 555 static int
 556 fifo_close(struct vop_close_args *ap)
 557 {
 558         struct vnode *vp = ap->a_vp;
 559         struct fifoinfo *fip;
 560         int error1, error2;
 561         lwkt_tokref vlock;
 562
 563         lwkt_gettoken(&vlock, &vp->v_token);
 564         fip = vp->v_fifoinfo;
 565         if (ap->a_fflag & FREAD) {
 566                 fip->fi_readers--;
 567                 if (fip->fi_readers == 0)
 568                         socantsendmore(fip->fi_writesock);
 569         }
 570         if (ap->a_fflag & FWRITE) {
 571                 fip->fi_writers--;
 572                 if (fip->fi_writers == 0)
 573                         socantrcvmore(fip->fi_readsock);
 574         }
 575         if (vp->v_sysref.refcnt > 1) {
 576                 vop_stdclose(ap);
 577                 lwkt_reltoken(&vlock);
 578                 return (0);
 579         }
 580         error1 = soclose(fip->fi_readsock, FNONBLOCK);
 581         error2 = soclose(fip->fi_writesock, FNONBLOCK);
 582         FREE(fip, M_FIFOINFO);
 583         vp->v_fifoinfo = NULL;
 584         if (error1) {
 585                 error2 = error1;
 586         } else {
 587                 vop_stdclose(ap);
 588         }
 589         lwkt_reltoken(&vlock);
 590         return (error2);
 591 }
 592
 593
 594 /*
 595  * Print out internal contents of a fifo vnode.
 596  */
 597 int
 598 fifo_printinfo(struct vnode *vp)
 599 {
 600         struct fifoinfo *fip = vp->v_fifoinfo;
 601
 602         kprintf(", fifo with %ld readers and %ld writers",
 603                 fip->fi_readers, fip->fi_writers);
 604         return (0);
 605 }
 606
 607 /*
 608  * Print out the contents of a fifo vnode.
 609  *
 610  * fifo_print(struct vnode *a_vp)
 611  */
 612 static int
 613 fifo_print(struct vop_print_args *ap)
 614 {
 615         kprintf("tag VT_NON");
 616         fifo_printinfo(ap->a_vp);
 617         kprintf("\n");
 618         return (0);
 619 }
 620
 621 /*
 622  * Return POSIX pathconf information applicable to fifo's.
 623  *
 624  * fifo_pathconf(struct vnode *a_vp, int a_name, int *a_retval)
 625  */
 626 int
 627 fifo_pathconf(struct vop_pathconf_args *ap)
 628 {
 629         switch (ap->a_name) {
 630         case _PC_LINK_MAX:
 631                 *ap->a_retval = LINK_MAX;
 632                 return (0);
 633         case _PC_PIPE_BUF:
 634                 *ap->a_retval = PIPE_BUF;
 635                 return (0);
 636         case _PC_CHOWN_RESTRICTED:
 637                 *ap->a_retval = 1;
 638                 return (0);
 639         default:
 640                 return (EINVAL);
 641         }
 642         /* NOTREACHED */
 643 }
 644
 645 /*
 646  * Fifo advisory byte-level locks.
 647  *
 648  * fifo_advlock(struct vnode *a_vp, caddr_t a_id, int a_op, struct flock *a_fl,
 649  *              int a_flags)
 650  */
 651 /* ARGSUSED */
 652 static int
 653 fifo_advlock(struct vop_advlock_args *ap)
 654 {
 655         return ((ap->a_flags & F_POSIX) ? EINVAL : EOPNOTSUPP);
 656 }
 657
 658 /*
 659  * Fifo bad operation
 660  */
 661 static int
 662 fifo_badop(void)
 663 {
 664         panic("fifo_badop called");
 665         /* NOTREACHED */
 666 }