sys/kern/sys_pipe.c

   1 /*-
   2  * Copyright (c) 1996 John S. Dyson
   3  * 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 immediately at the beginning of the file, without modification,
  10  *    this list of conditions, and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. Absolutely no warranty of function or purpose is made by the author
  15  *    John S. Dyson.
  16  * 4. Modifications may be freely made to this file if the above conditions
  17  *    are met.
  18  */
  19
  20 /*
  21  * This file contains a high-performance replacement for the socket-based
  22  * pipes scheme originally used in FreeBSD/4.4Lite.  It does not support
  23  * all features of sockets, but does do everything that pipes normally
  24  * do.
  25  */
  26
  27 /*
  28  * This code has two modes of operation, a small write mode and a large
  29  * write mode.  The small write mode acts like conventional pipes with
  30  * a kernel buffer.  If the buffer is less than PIPE_MINDIRECT, then the
  31  * "normal" pipe buffering is done.  If the buffer is between PIPE_MINDIRECT
  32  * and PIPE_SIZE in size, the sending process pins the underlying pages in
  33  * memory, and the receiving process copies directly from these pinned pages
  34  * in the sending process.
  35  *
  36  * If the sending process receives a signal, it is possible that it will
  37  * go away, and certainly its address space can change, because control
  38  * is returned back to the user-mode side.  In that case, the pipe code
  39  * arranges to copy the buffer supplied by the user process, to a pageable
  40  * kernel buffer, and the receiving process will grab the data from the
  41  * pageable kernel buffer.  Since signals don't happen all that often,
  42  * the copy operation is normally eliminated.
  43  *
  44  * The constant PIPE_MINDIRECT is chosen to make sure that buffering will
  45  * happen for small transfers so that the system will not spend all of
  46  * its time context switching.
  47  *
  48  * In order to limit the resource use of pipes, two sysctls exist:
  49  *
  50  * kern.ipc.maxpipekva - This is a hard limit on the amount of pageable
  51  * address space available to us in pipe_map. This value is normally
  52  * autotuned, but may also be loader tuned.
  53  *
  54  * kern.ipc.pipekva - This read-only sysctl tracks the current amount of
  55  * memory in use by pipes.
  56  *
  57  * Based on how large pipekva is relative to maxpipekva, the following
  58  * will happen:
  59  *
  60  * 0% - 50%:
  61  *     New pipes are given 16K of memory backing, pipes may dynamically
  62  *     grow to as large as 64K where needed.
  63  * 50% - 75%:
  64  *     New pipes are given 4K (or PAGE_SIZE) of memory backing,
  65  *     existing pipes may NOT grow.
  66  * 75% - 100%:
  67  *     New pipes are given 4K (or PAGE_SIZE) of memory backing,
  68  *     existing pipes will be shrunk down to 4K whenever possible.
  69  *
  70  * Resizing may be disabled by setting kern.ipc.piperesizeallowed=0.  If
  71  * that is set,  the only resize that will occur is the 0 -> SMALL_PIPE_SIZE
  72  * resize which MUST occur for reverse-direction pipes when they are
  73  * first used.
  74  *
  75  * Additional information about the current state of pipes may be obtained
  76  * from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail,
  77  * and kern.ipc.piperesizefail.
  78  *
  79  * Locking rules:  There are two locks present here:  A mutex, used via
  80  * PIPE_LOCK, and a flag, used via pipelock().  All locking is done via
  81  * the flag, as mutexes can not persist over uiomove.  The mutex
  82  * exists only to guard access to the flag, and is not in itself a
  83  * locking mechanism.  Also note that there is only a single mutex for
  84  * both directions of a pipe.
  85  *
  86  * As pipelock() may have to sleep before it can acquire the flag, it
  87  * is important to reread all data after a call to pipelock(); everything
  88  * in the structure may have changed.
  89  */
  90
  91 #include <sys/cdefs.h>
  92 __FBSDID("$FreeBSD$");
  93
  94 #include <sys/param.h>
  95 #include <sys/systm.h>
  96 #include <sys/fcntl.h>
  97 #include <sys/file.h>
  98 #include <sys/filedesc.h>
  99 #include <sys/filio.h>
 100 #include <sys/kernel.h>
 101 #include <sys/lock.h>
 102 #include <sys/mutex.h>
 103 #include <sys/ttycom.h>
 104 #include <sys/stat.h>
 105 #include <sys/malloc.h>
 106 #include <sys/poll.h>
 107 #include <sys/selinfo.h>
 108 #include <sys/signalvar.h>
 109 #include <sys/syscallsubr.h>
 110 #include <sys/sysctl.h>
 111 #include <sys/sysproto.h>
 112 #include <sys/pipe.h>
 113 #include <sys/proc.h>
 114 #include <sys/vnode.h>
 115 #include <sys/uio.h>
 116 #include <sys/event.h>
 117
 118 #include <security/mac/mac_framework.h>
 119
 120 #include <vm/vm.h>
 121 #include <vm/vm_param.h>
 122 #include <vm/vm_object.h>
 123 #include <vm/vm_kern.h>
 124 #include <vm/vm_extern.h>
 125 #include <vm/pmap.h>
 126 #include <vm/vm_map.h>
 127 #include <vm/vm_page.h>
 128 #include <vm/uma.h>
 129
 130 /*
 131  * Use this define if you want to disable *fancy* VM things.  Expect an
 132  * approx 30% decrease in transfer rate.  This could be useful for
 133  * NetBSD or OpenBSD.
 134  */
 135 /* #define PIPE_NODIRECT */
 136
 137 /*
 138  * interfaces to the outside world
 139  */
 140 static fo_rdwr_t        pipe_read;
 141 static fo_rdwr_t        pipe_write;
 142 static fo_truncate_t    pipe_truncate;
 143 static fo_ioctl_t       pipe_ioctl;
 144 static fo_poll_t        pipe_poll;
 145 static fo_kqfilter_t    pipe_kqfilter;
 146 static fo_stat_t        pipe_stat;
 147 static fo_close_t       pipe_close;
 148
 149 static struct fileops pipeops = {
 150         .fo_read = pipe_read,
 151         .fo_write = pipe_write,
 152         .fo_truncate = pipe_truncate,
 153         .fo_ioctl = pipe_ioctl,
 154         .fo_poll = pipe_poll,
 155         .fo_kqfilter = pipe_kqfilter,
 156         .fo_stat = pipe_stat,
 157         .fo_close = pipe_close,
 158         .fo_chmod = invfo_chmod,
 159         .fo_chown = invfo_chown,
 160         .fo_flags = DFLAG_PASSABLE
 161 };
 162
 163 static void     filt_pipedetach(struct knote *kn);
 164 static int      filt_piperead(struct knote *kn, long hint);
 165 static int      filt_pipewrite(struct knote *kn, long hint);
 166
 167 static struct filterops pipe_rfiltops = {
 168         .f_isfd = 1,
 169         .f_detach = filt_pipedetach,
 170         .f_event = filt_piperead
 171 };
 172 static struct filterops pipe_wfiltops = {
 173         .f_isfd = 1,
 174         .f_detach = filt_pipedetach,
 175         .f_event = filt_pipewrite
 176 };
 177
 178 /*
 179  * Default pipe buffer size(s), this can be kind-of large now because pipe
 180  * space is pageable.  The pipe code will try to maintain locality of
 181  * reference for performance reasons, so small amounts of outstanding I/O
 182  * will not wipe the cache.
 183  */
 184 #define MINPIPESIZE (PIPE_SIZE/3)
 185 #define MAXPIPESIZE (2*PIPE_SIZE/3)
 186
 187 static long amountpipekva;
 188 static int pipefragretry;
 189 static int pipeallocfail;
 190 static int piperesizefail;
 191 static int piperesizeallowed = 1;
 192
 193 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN,
 194            &maxpipekva, 0, "Pipe KVA limit");
 195 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD,
 196            &amountpipekva, 0, "Pipe KVA usage");
 197 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD,
 198           &pipefragretry, 0, "Pipe allocation retries due to fragmentation");
 199 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD,
 200           &pipeallocfail, 0, "Pipe allocation failures");
 201 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD,
 202           &piperesizefail, 0, "Pipe resize failures");
 203 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW,
 204           &piperesizeallowed, 0, "Pipe resizing allowed");
 205
 206 static void pipeinit(void *dummy __unused);
 207 static void pipeclose(struct pipe *cpipe);
 208 static void pipe_free_kmem(struct pipe *cpipe);
 209 static int pipe_create(struct pipe *pipe, int backing);
 210 static __inline int pipelock(struct pipe *cpipe, int catch);
 211 static __inline void pipeunlock(struct pipe *cpipe);
 212 static __inline void pipeselwakeup(struct pipe *cpipe);
 213 #ifndef PIPE_NODIRECT
 214 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio);
 215 static void pipe_destroy_write_buffer(struct pipe *wpipe);
 216 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio);
 217 static void pipe_clone_write_buffer(struct pipe *wpipe);
 218 #endif
 219 static int pipespace(struct pipe *cpipe, int size);
 220 static int pipespace_new(struct pipe *cpipe, int size);
 221
 222 static int      pipe_zone_ctor(void *mem, int size, void *arg, int flags);
 223 static int      pipe_zone_init(void *mem, int size, int flags);
 224 static void     pipe_zone_fini(void *mem, int size);
 225
 226 static uma_zone_t pipe_zone;
 227
 228 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
 229
 230 static void
 231 pipeinit(void *dummy __unused)
 232 {
 233
 234         pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair),
 235             pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini,
 236             UMA_ALIGN_PTR, 0);
 237         KASSERT(pipe_zone != NULL, ("pipe_zone not initialized"));
 238 }
 239
 240 static int
 241 pipe_zone_ctor(void *mem, int size, void *arg, int flags)
 242 {
 243         struct pipepair *pp;
 244         struct pipe *rpipe, *wpipe;
 245
 246         KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size"));
 247
 248         pp = (struct pipepair *)mem;
 249
 250         /*
 251          * We zero both pipe endpoints to make sure all the kmem pointers
 252          * are NULL, flag fields are zero'd, etc.  We timestamp both
 253          * endpoints with the same time.
 254          */
 255         rpipe = &pp->pp_rpipe;
 256         bzero(rpipe, sizeof(*rpipe));
 257         vfs_timestamp(&rpipe->pipe_ctime);
 258         rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime;
 259
 260         wpipe = &pp->pp_wpipe;
 261         bzero(wpipe, sizeof(*wpipe));
 262         wpipe->pipe_ctime = rpipe->pipe_ctime;
 263         wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime;
 264
 265         rpipe->pipe_peer = wpipe;
 266         rpipe->pipe_pair = pp;
 267         wpipe->pipe_peer = rpipe;
 268         wpipe->pipe_pair = pp;
 269
 270         /*
 271          * Mark both endpoints as present; they will later get free'd
 272          * one at a time.  When both are free'd, then the whole pair
 273          * is released.
 274          */
 275         rpipe->pipe_present = PIPE_ACTIVE;
 276         wpipe->pipe_present = PIPE_ACTIVE;
 277
 278         /*
 279          * Eventually, the MAC Framework may initialize the label
 280          * in ctor or init, but for now we do it elswhere to avoid
 281          * blocking in ctor or init.
 282          */
 283         pp->pp_label = NULL;
 284
 285         return (0);
 286 }
 287
 288 static int
 289 pipe_zone_init(void *mem, int size, int flags)
 290 {
 291         struct pipepair *pp;
 292
 293         KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size"));
 294
 295         pp = (struct pipepair *)mem;
 296
 297         mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_RECURSE);
 298         return (0);
 299 }
 300
 301 static void
 302 pipe_zone_fini(void *mem, int size)
 303 {
 304         struct pipepair *pp;
 305
 306         KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size"));
 307
 308         pp = (struct pipepair *)mem;
 309
 310         mtx_destroy(&pp->pp_mtx);
 311 }
 312
 313 /*
 314  * The pipe system call for the DTYPE_PIPE type of pipes.  If we fail, let
 315  * the zone pick up the pieces via pipeclose().
 316  */
 317 int
 318 kern_pipe(struct thread *td, int fildes[2])
 319 {
 320         struct filedesc *fdp = td->td_proc->p_fd;
 321         struct file *rf, *wf;
 322         struct pipepair *pp;
 323         struct pipe *rpipe, *wpipe;
 324         int fd, error;
 325
 326         pp = uma_zalloc(pipe_zone, M_WAITOK);
 327 #ifdef MAC
 328         /*
 329          * The MAC label is shared between the connected endpoints.  As a
 330          * result mac_pipe_init() and mac_pipe_create() are called once
 331          * for the pair, and not on the endpoints.
 332          */
 333         mac_pipe_init(pp);
 334         mac_pipe_create(td->td_ucred, pp);
 335 #endif
 336         rpipe = &pp->pp_rpipe;
 337         wpipe = &pp->pp_wpipe;
 338
 339         knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe));
 340         knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe));
 341
 342         /* Only the forward direction pipe is backed by default */
 343         if ((error = pipe_create(rpipe, 1)) != 0 ||
 344             (error = pipe_create(wpipe, 0)) != 0) {
 345                 pipeclose(rpipe);
 346                 pipeclose(wpipe);
 347                 return (error);
 348         }
 349
 350         rpipe->pipe_state |= PIPE_DIRECTOK;
 351         wpipe->pipe_state |= PIPE_DIRECTOK;
 352
 353         error = falloc(td, &rf, &fd, 0);
 354         if (error) {
 355                 pipeclose(rpipe);
 356                 pipeclose(wpipe);
 357                 return (error);
 358         }
 359         /* An extra reference on `rf' has been held for us by falloc(). */
 360         fildes[0] = fd;
 361
 362         /*
 363          * Warning: once we've gotten past allocation of the fd for the
 364          * read-side, we can only drop the read side via fdrop() in order
 365          * to avoid races against processes which manage to dup() the read
 366          * side while we are blocked trying to allocate the write side.
 367          */
 368         finit(rf, FREAD | FWRITE, DTYPE_PIPE, rpipe, &pipeops);
 369         error = falloc(td, &wf, &fd, 0);
 370         if (error) {
 371                 fdclose(fdp, rf, fildes[0], td);
 372                 fdrop(rf, td);
 373                 /* rpipe has been closed by fdrop(). */
 374                 pipeclose(wpipe);
 375                 return (error);
 376         }
 377         /* An extra reference on `wf' has been held for us by falloc(). */
 378         finit(wf, FREAD | FWRITE, DTYPE_PIPE, wpipe, &pipeops);
 379         fdrop(wf, td);
 380         fildes[1] = fd;
 381         fdrop(rf, td);
 382
 383         return (0);
 384 }
 385
 386 /* ARGSUSED */
 387 int
 388 sys_pipe(struct thread *td, struct pipe_args *uap)
 389 {
 390         int error;
 391         int fildes[2];
 392
 393         error = kern_pipe(td, fildes);
 394         if (error)
 395                 return (error);
 396
 397         td->td_retval[0] = fildes[0];
 398         td->td_retval[1] = fildes[1];
 399
 400         return (0);
 401 }
 402
 403 /*
 404  * Allocate kva for pipe circular buffer, the space is pageable
 405  * This routine will 'realloc' the size of a pipe safely, if it fails
 406  * it will retain the old buffer.
 407  * If it fails it will return ENOMEM.
 408  */
 409 static int
 410 pipespace_new(cpipe, size)
 411         struct pipe *cpipe;
 412         int size;
 413 {
 414         caddr_t buffer;
 415         int error, cnt, firstseg;
 416         static int curfail = 0;
 417         static struct timeval lastfail;
 418
 419         KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked"));
 420         KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW),
 421                 ("pipespace: resize of direct writes not allowed"));
 422 retry:
 423         cnt = cpipe->pipe_buffer.cnt;
 424         if (cnt > size)
 425                 size = cnt;
 426
 427         size = round_page(size);
 428         buffer = (caddr_t) vm_map_min(pipe_map);
 429
 430         error = vm_map_find(pipe_map, NULL, 0,
 431                 (vm_offset_t *) &buffer, size, 1,
 432                 VM_PROT_ALL, VM_PROT_ALL, 0);
 433         if (error != KERN_SUCCESS) {
 434                 if ((cpipe->pipe_buffer.buffer == NULL) &&
 435                         (size > SMALL_PIPE_SIZE)) {
 436                         size = SMALL_PIPE_SIZE;
 437                         pipefragretry++;
 438                         goto retry;
 439                 }
 440                 if (cpipe->pipe_buffer.buffer == NULL) {
 441                         pipeallocfail++;
 442                         if (ppsratecheck(&lastfail, &curfail, 1))
 443                                 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n");
 444                 } else {
 445                         piperesizefail++;
 446                 }
 447                 return (ENOMEM);
 448         }
 449
 450         /* copy data, then free old resources if we're resizing */
 451         if (cnt > 0) {
 452                 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) {
 453                         firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out;
 454                         bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
 455                                 buffer, firstseg);
 456                         if ((cnt - firstseg) > 0)
 457                                 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg],
 458                                         cpipe->pipe_buffer.in);
 459                 } else {
 460                         bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
 461                                 buffer, cnt);
 462                 }
 463         }
 464         pipe_free_kmem(cpipe);
 465         cpipe->pipe_buffer.buffer = buffer;
 466         cpipe->pipe_buffer.size = size;
 467         cpipe->pipe_buffer.in = cnt;
 468         cpipe->pipe_buffer.out = 0;
 469         cpipe->pipe_buffer.cnt = cnt;
 470         atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size);
 471         return (0);
 472 }
 473
 474 /*
 475  * Wrapper for pipespace_new() that performs locking assertions.
 476  */
 477 static int
 478 pipespace(cpipe, size)
 479         struct pipe *cpipe;
 480         int size;
 481 {
 482
 483         KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
 484                 ("Unlocked pipe passed to pipespace"));
 485         return (pipespace_new(cpipe, size));
 486 }
 487
 488 /*
 489  * lock a pipe for I/O, blocking other access
 490  */
 491 static __inline int
 492 pipelock(cpipe, catch)
 493         struct pipe *cpipe;
 494         int catch;
 495 {
 496         int error;
 497
 498         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 499         while (cpipe->pipe_state & PIPE_LOCKFL) {
 500                 cpipe->pipe_state |= PIPE_LWANT;
 501                 error = msleep(cpipe, PIPE_MTX(cpipe),
 502                     catch ? (PRIBIO | PCATCH) : PRIBIO,
 503                     "pipelk", 0);
 504                 if (error != 0)
 505                         return (error);
 506         }
 507         cpipe->pipe_state |= PIPE_LOCKFL;
 508         return (0);
 509 }
 510
 511 /*
 512  * unlock a pipe I/O lock
 513  */
 514 static __inline void
 515 pipeunlock(cpipe)
 516         struct pipe *cpipe;
 517 {
 518
 519         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 520         KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
 521                 ("Unlocked pipe passed to pipeunlock"));
 522         cpipe->pipe_state &= ~PIPE_LOCKFL;
 523         if (cpipe->pipe_state & PIPE_LWANT) {
 524                 cpipe->pipe_state &= ~PIPE_LWANT;
 525                 wakeup(cpipe);
 526         }
 527 }
 528
 529 static __inline void
 530 pipeselwakeup(cpipe)
 531         struct pipe *cpipe;
 532 {
 533
 534         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 535         if (cpipe->pipe_state & PIPE_SEL) {
 536                 selwakeuppri(&cpipe->pipe_sel, PSOCK);
 537                 if (!SEL_WAITING(&cpipe->pipe_sel))
 538                         cpipe->pipe_state &= ~PIPE_SEL;
 539         }
 540         if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
 541                 pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
 542         KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0);
 543 }
 544
 545 /*
 546  * Initialize and allocate VM and memory for pipe.  The structure
 547  * will start out zero'd from the ctor, so we just manage the kmem.
 548  */
 549 static int
 550 pipe_create(pipe, backing)
 551         struct pipe *pipe;
 552         int backing;
 553 {
 554         int error;
 555
 556         if (backing) {
 557                 if (amountpipekva > maxpipekva / 2)
 558                         error = pipespace_new(pipe, SMALL_PIPE_SIZE);
 559                 else
 560                         error = pipespace_new(pipe, PIPE_SIZE);
 561         } else {
 562                 /* If we're not backing this pipe, no need to do anything. */
 563                 error = 0;
 564         }
 565         return (error);
 566 }
 567
 568 /* ARGSUSED */
 569 static int
 570 pipe_read(fp, uio, active_cred, flags, td)
 571         struct file *fp;
 572         struct uio *uio;
 573         struct ucred *active_cred;
 574         struct thread *td;
 575         int flags;
 576 {
 577         struct pipe *rpipe = fp->f_data;
 578         int error;
 579         int nread = 0;
 580         u_int size;
 581
 582         PIPE_LOCK(rpipe);
 583         ++rpipe->pipe_busy;
 584         error = pipelock(rpipe, 1);
 585         if (error)
 586                 goto unlocked_error;
 587
 588 #ifdef MAC
 589         error = mac_pipe_check_read(active_cred, rpipe->pipe_pair);
 590         if (error)
 591                 goto locked_error;
 592 #endif
 593         if (amountpipekva > (3 * maxpipekva) / 4) {
 594                 if (!(rpipe->pipe_state & PIPE_DIRECTW) &&
 595                         (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
 596                         (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
 597                         (piperesizeallowed == 1)) {
 598                         PIPE_UNLOCK(rpipe);
 599                         pipespace(rpipe, SMALL_PIPE_SIZE);
 600                         PIPE_LOCK(rpipe);
 601                 }
 602         }
 603
 604         while (uio->uio_resid) {
 605                 /*
 606                  * normal pipe buffer receive
 607                  */
 608                 if (rpipe->pipe_buffer.cnt > 0) {
 609                         size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
 610                         if (size > rpipe->pipe_buffer.cnt)
 611                                 size = rpipe->pipe_buffer.cnt;
 612                         if (size > (u_int) uio->uio_resid)
 613                                 size = (u_int) uio->uio_resid;
 614
 615                         PIPE_UNLOCK(rpipe);
 616                         error = uiomove(
 617                             &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
 618                             size, uio);
 619                         PIPE_LOCK(rpipe);
 620                         if (error)
 621                                 break;
 622
 623                         rpipe->pipe_buffer.out += size;
 624                         if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
 625                                 rpipe->pipe_buffer.out = 0;
 626
 627                         rpipe->pipe_buffer.cnt -= size;
 628
 629                         /*
 630                          * If there is no more to read in the pipe, reset
 631                          * its pointers to the beginning.  This improves
 632                          * cache hit stats.
 633                          */
 634                         if (rpipe->pipe_buffer.cnt == 0) {
 635                                 rpipe->pipe_buffer.in = 0;
 636                                 rpipe->pipe_buffer.out = 0;
 637                         }
 638                         nread += size;
 639 #ifndef PIPE_NODIRECT
 640                 /*
 641                  * Direct copy, bypassing a kernel buffer.
 642                  */
 643                 } else if ((size = rpipe->pipe_map.cnt) &&
 644                            (rpipe->pipe_state & PIPE_DIRECTW)) {
 645                         if (size > (u_int) uio->uio_resid)
 646                                 size = (u_int) uio->uio_resid;
 647
 648                         PIPE_UNLOCK(rpipe);
 649                         error = uiomove_fromphys(rpipe->pipe_map.ms,
 650                             rpipe->pipe_map.pos, size, uio);
 651                         PIPE_LOCK(rpipe);
 652                         if (error)
 653                                 break;
 654                         nread += size;
 655                         rpipe->pipe_map.pos += size;
 656                         rpipe->pipe_map.cnt -= size;
 657                         if (rpipe->pipe_map.cnt == 0) {
 658                                 rpipe->pipe_state &= ~PIPE_DIRECTW;
 659                                 wakeup(rpipe);
 660                         }
 661 #endif
 662                 } else {
 663                         /*
 664                          * detect EOF condition
 665                          * read returns 0 on EOF, no need to set error
 666                          */
 667                         if (rpipe->pipe_state & PIPE_EOF)
 668                                 break;
 669
 670                         /*
 671                          * If the "write-side" has been blocked, wake it up now.
 672                          */
 673                         if (rpipe->pipe_state & PIPE_WANTW) {
 674                                 rpipe->pipe_state &= ~PIPE_WANTW;
 675                                 wakeup(rpipe);
 676                         }
 677
 678                         /*
 679                          * Break if some data was read.
 680                          */
 681                         if (nread > 0)
 682                                 break;
 683
 684                         /*
 685                          * Unlock the pipe buffer for our remaining processing.
 686                          * We will either break out with an error or we will
 687                          * sleep and relock to loop.
 688                          */
 689                         pipeunlock(rpipe);
 690
 691                         /*
 692                          * Handle non-blocking mode operation or
 693                          * wait for more data.
 694                          */
 695                         if (fp->f_flag & FNONBLOCK) {
 696                                 error = EAGAIN;
 697                         } else {
 698                                 rpipe->pipe_state |= PIPE_WANTR;
 699                                 if ((error = msleep(rpipe, PIPE_MTX(rpipe),
 700                                     PRIBIO | PCATCH,
 701                                     "piperd", 0)) == 0)
 702                                         error = pipelock(rpipe, 1);
 703                         }
 704                         if (error)
 705                                 goto unlocked_error;
 706                 }
 707         }
 708 #ifdef MAC
 709 locked_error:
 710 #endif
 711         pipeunlock(rpipe);
 712
 713         /* XXX: should probably do this before getting any locks. */
 714         if (error == 0)
 715                 vfs_timestamp(&rpipe->pipe_atime);
 716 unlocked_error:
 717         --rpipe->pipe_busy;
 718
 719         /*
 720          * PIPE_WANT processing only makes sense if pipe_busy is 0.
 721          */
 722         if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
 723                 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
 724                 wakeup(rpipe);
 725         } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
 726                 /*
 727                  * Handle write blocking hysteresis.
 728                  */
 729                 if (rpipe->pipe_state & PIPE_WANTW) {
 730                         rpipe->pipe_state &= ~PIPE_WANTW;
 731                         wakeup(rpipe);
 732                 }
 733         }
 734
 735         if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
 736                 pipeselwakeup(rpipe);
 737
 738         PIPE_UNLOCK(rpipe);
 739         return (error);
 740 }
 741
 742 #ifndef PIPE_NODIRECT
 743 /*
 744  * Map the sending processes' buffer into kernel space and wire it.
 745  * This is similar to a physical write operation.
 746  */
 747 static int
 748 pipe_build_write_buffer(wpipe, uio)
 749         struct pipe *wpipe;
 750         struct uio *uio;
 751 {
 752         u_int size;
 753         int i;
 754
 755         PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED);
 756         KASSERT(wpipe->pipe_state & PIPE_DIRECTW,
 757                 ("Clone attempt on non-direct write pipe!"));
 758
 759         size = (u_int) uio->uio_iov->iov_len;
 760         if (size > wpipe->pipe_buffer.size)
 761                 size = wpipe->pipe_buffer.size;
 762
 763         if ((i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
 764             (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ,
 765             wpipe->pipe_map.ms, PIPENPAGES)) < 0)
 766                 return (EFAULT);
 767
 768 /*
 769  * set up the control block
 770  */
 771         wpipe->pipe_map.npages = i;
 772         wpipe->pipe_map.pos =
 773             ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK;
 774         wpipe->pipe_map.cnt = size;
 775
 776 /*
 777  * and update the uio data
 778  */
 779
 780         uio->uio_iov->iov_len -= size;
 781         uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size;
 782         if (uio->uio_iov->iov_len == 0)
 783                 uio->uio_iov++;
 784         uio->uio_resid -= size;
 785         uio->uio_offset += size;
 786         return (0);
 787 }
 788
 789 /*
 790  * unmap and unwire the process buffer
 791  */
 792 static void
 793 pipe_destroy_write_buffer(wpipe)
 794         struct pipe *wpipe;
 795 {
 796
 797         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 798         vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages);
 799         wpipe->pipe_map.npages = 0;
 800 }
 801
 802 /*
 803  * In the case of a signal, the writing process might go away.  This
 804  * code copies the data into the circular buffer so that the source
 805  * pages can be freed without loss of data.
 806  */
 807 static void
 808 pipe_clone_write_buffer(wpipe)
 809         struct pipe *wpipe;
 810 {
 811         struct uio uio;
 812         struct iovec iov;
 813         int size;
 814         int pos;
 815
 816         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 817         size = wpipe->pipe_map.cnt;
 818         pos = wpipe->pipe_map.pos;
 819
 820         wpipe->pipe_buffer.in = size;
 821         wpipe->pipe_buffer.out = 0;
 822         wpipe->pipe_buffer.cnt = size;
 823         wpipe->pipe_state &= ~PIPE_DIRECTW;
 824
 825         PIPE_UNLOCK(wpipe);
 826         iov.iov_base = wpipe->pipe_buffer.buffer;
 827         iov.iov_len = size;
 828         uio.uio_iov = &iov;
 829         uio.uio_iovcnt = 1;
 830         uio.uio_offset = 0;
 831         uio.uio_resid = size;
 832         uio.uio_segflg = UIO_SYSSPACE;
 833         uio.uio_rw = UIO_READ;
 834         uio.uio_td = curthread;
 835         uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio);
 836         PIPE_LOCK(wpipe);
 837         pipe_destroy_write_buffer(wpipe);
 838 }
 839
 840 /*
 841  * This implements the pipe buffer write mechanism.  Note that only
 842  * a direct write OR a normal pipe write can be pending at any given time.
 843  * If there are any characters in the pipe buffer, the direct write will
 844  * be deferred until the receiving process grabs all of the bytes from
 845  * the pipe buffer.  Then the direct mapping write is set-up.
 846  */
 847 static int
 848 pipe_direct_write(wpipe, uio)
 849         struct pipe *wpipe;
 850         struct uio *uio;
 851 {
 852         int error;
 853
 854 retry:
 855         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 856         error = pipelock(wpipe, 1);
 857         if (wpipe->pipe_state & PIPE_EOF)
 858                 error = EPIPE;
 859         if (error) {
 860                 pipeunlock(wpipe);
 861                 goto error1;
 862         }
 863         while (wpipe->pipe_state & PIPE_DIRECTW) {
 864                 if (wpipe->pipe_state & PIPE_WANTR) {
 865                         wpipe->pipe_state &= ~PIPE_WANTR;
 866                         wakeup(wpipe);
 867                 }
 868                 pipeselwakeup(wpipe);
 869                 wpipe->pipe_state |= PIPE_WANTW;
 870                 pipeunlock(wpipe);
 871                 error = msleep(wpipe, PIPE_MTX(wpipe),
 872                     PRIBIO | PCATCH, "pipdww", 0);
 873                 if (error)
 874                         goto error1;
 875                 else
 876                         goto retry;
 877         }
 878         wpipe->pipe_map.cnt = 0;        /* transfer not ready yet */
 879         if (wpipe->pipe_buffer.cnt > 0) {
 880                 if (wpipe->pipe_state & PIPE_WANTR) {
 881                         wpipe->pipe_state &= ~PIPE_WANTR;
 882                         wakeup(wpipe);
 883                 }
 884                 pipeselwakeup(wpipe);
 885                 wpipe->pipe_state |= PIPE_WANTW;
 886                 pipeunlock(wpipe);
 887                 error = msleep(wpipe, PIPE_MTX(wpipe),
 888                     PRIBIO | PCATCH, "pipdwc", 0);
 889                 if (error)
 890                         goto error1;
 891                 else
 892                         goto retry;
 893         }
 894
 895         wpipe->pipe_state |= PIPE_DIRECTW;
 896
 897         PIPE_UNLOCK(wpipe);
 898         error = pipe_build_write_buffer(wpipe, uio);
 899         PIPE_LOCK(wpipe);
 900         if (error) {
 901                 wpipe->pipe_state &= ~PIPE_DIRECTW;
 902                 pipeunlock(wpipe);
 903                 goto error1;
 904         }
 905
 906         error = 0;
 907         while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
 908                 if (wpipe->pipe_state & PIPE_EOF) {
 909                         pipe_destroy_write_buffer(wpipe);
 910                         pipeselwakeup(wpipe);
 911                         pipeunlock(wpipe);
 912                         error = EPIPE;
 913                         goto error1;
 914                 }
 915                 if (wpipe->pipe_state & PIPE_WANTR) {
 916                         wpipe->pipe_state &= ~PIPE_WANTR;
 917                         wakeup(wpipe);
 918                 }
 919                 pipeselwakeup(wpipe);
 920                 pipeunlock(wpipe);
 921                 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
 922                     "pipdwt", 0);
 923                 pipelock(wpipe, 0);
 924         }
 925
 926         if (wpipe->pipe_state & PIPE_EOF)
 927                 error = EPIPE;
 928         if (wpipe->pipe_state & PIPE_DIRECTW) {
 929                 /*
 930                  * this bit of trickery substitutes a kernel buffer for
 931                  * the process that might be going away.
 932                  */
 933                 pipe_clone_write_buffer(wpipe);
 934         } else {
 935                 pipe_destroy_write_buffer(wpipe);
 936         }
 937         pipeunlock(wpipe);
 938         return (error);
 939
 940 error1:
 941         wakeup(wpipe);
 942         return (error);
 943 }
 944 #endif
 945
 946 static int
 947 pipe_write(fp, uio, active_cred, flags, td)
 948         struct file *fp;
 949         struct uio *uio;
 950         struct ucred *active_cred;
 951         struct thread *td;
 952         int flags;
 953 {
 954         int error = 0;
 955         int desiredsize, orig_resid;
 956         struct pipe *wpipe, *rpipe;
 957
 958         rpipe = fp->f_data;
 959         wpipe = rpipe->pipe_peer;
 960
 961         PIPE_LOCK(rpipe);
 962         error = pipelock(wpipe, 1);
 963         if (error) {
 964                 PIPE_UNLOCK(rpipe);
 965                 return (error);
 966         }
 967         /*
 968          * detect loss of pipe read side, issue SIGPIPE if lost.
 969          */
 970         if (wpipe->pipe_present != PIPE_ACTIVE ||
 971             (wpipe->pipe_state & PIPE_EOF)) {
 972                 pipeunlock(wpipe);
 973                 PIPE_UNLOCK(rpipe);
 974                 return (EPIPE);
 975         }
 976 #ifdef MAC
 977         error = mac_pipe_check_write(active_cred, wpipe->pipe_pair);
 978         if (error) {
 979                 pipeunlock(wpipe);
 980                 PIPE_UNLOCK(rpipe);
 981                 return (error);
 982         }
 983 #endif
 984         ++wpipe->pipe_busy;
 985
 986         /* Choose a larger size if it's advantageous */
 987         desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size);
 988         while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) {
 989                 if (piperesizeallowed != 1)
 990                         break;
 991                 if (amountpipekva > maxpipekva / 2)
 992                         break;
 993                 if (desiredsize == BIG_PIPE_SIZE)
 994                         break;
 995                 desiredsize = desiredsize * 2;
 996         }
 997
 998         /* Choose a smaller size if we're in a OOM situation */
 999         if ((amountpipekva > (3 * maxpipekva) / 4) &&
1000                 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
1001                 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
1002                 (piperesizeallowed == 1))
1003                 desiredsize = SMALL_PIPE_SIZE;
1004
1005         /* Resize if the above determined that a new size was necessary */
1006         if ((desiredsize != wpipe->pipe_buffer.size) &&
1007                 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) {
1008                 PIPE_UNLOCK(wpipe);
1009                 pipespace(wpipe, desiredsize);
1010                 PIPE_LOCK(wpipe);
1011         }
1012         if (wpipe->pipe_buffer.size == 0) {
1013                 /*
1014                  * This can only happen for reverse direction use of pipes
1015                  * in a complete OOM situation.
1016                  */
1017                 error = ENOMEM;
1018                 --wpipe->pipe_busy;
1019                 pipeunlock(wpipe);
1020                 PIPE_UNLOCK(wpipe);
1021                 return (error);
1022         }
1023
1024         pipeunlock(wpipe);
1025
1026         orig_resid = uio->uio_resid;
1027
1028         while (uio->uio_resid) {
1029                 int space;
1030
1031                 pipelock(wpipe, 0);
1032                 if (wpipe->pipe_state & PIPE_EOF) {
1033                         pipeunlock(wpipe);
1034                         error = EPIPE;
1035                         break;
1036                 }
1037 #ifndef PIPE_NODIRECT
1038                 /*
1039                  * If the transfer is large, we can gain performance if
1040                  * we do process-to-process copies directly.
1041                  * If the write is non-blocking, we don't use the
1042                  * direct write mechanism.
1043                  *
1044                  * The direct write mechanism will detect the reader going
1045                  * away on us.
1046                  */
1047                 if (uio->uio_segflg == UIO_USERSPACE &&
1048                     uio->uio_iov->iov_len >= PIPE_MINDIRECT &&
1049                     wpipe->pipe_buffer.size >= PIPE_MINDIRECT &&
1050                     (fp->f_flag & FNONBLOCK) == 0) {
1051                         pipeunlock(wpipe);
1052                         error = pipe_direct_write(wpipe, uio);
1053                         if (error)
1054                                 break;
1055                         continue;
1056                 }
1057 #endif
1058
1059                 /*
1060                  * Pipe buffered writes cannot be coincidental with
1061                  * direct writes.  We wait until the currently executing
1062                  * direct write is completed before we start filling the
1063                  * pipe buffer.  We break out if a signal occurs or the
1064                  * reader goes away.
1065                  */
1066                 if (wpipe->pipe_state & PIPE_DIRECTW) {
1067                         if (wpipe->pipe_state & PIPE_WANTR) {
1068                                 wpipe->pipe_state &= ~PIPE_WANTR;
1069                                 wakeup(wpipe);
1070                         }
1071                         pipeselwakeup(wpipe);
1072                         wpipe->pipe_state |= PIPE_WANTW;
1073                         pipeunlock(wpipe);
1074                         error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH,
1075                             "pipbww", 0);
1076                         if (error)
1077                                 break;
1078                         else
1079                                 continue;
1080                 }
1081
1082                 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1083
1084                 /* Writes of size <= PIPE_BUF must be atomic. */
1085                 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
1086                         space = 0;
1087
1088                 if (space > 0) {
1089                         int size;       /* Transfer size */
1090                         int segsize;    /* first segment to transfer */
1091
1092                         /*
1093                          * Transfer size is minimum of uio transfer
1094                          * and free space in pipe buffer.
1095                          */
1096                         if (space > uio->uio_resid)
1097                                 size = uio->uio_resid;
1098                         else
1099                                 size = space;
1100                         /*
1101                          * First segment to transfer is minimum of
1102                          * transfer size and contiguous space in
1103                          * pipe buffer.  If first segment to transfer
1104                          * is less than the transfer size, we've got
1105                          * a wraparound in the buffer.
1106                          */
1107                         segsize = wpipe->pipe_buffer.size -
1108                                 wpipe->pipe_buffer.in;
1109                         if (segsize > size)
1110                                 segsize = size;
1111
1112                         /* Transfer first segment */
1113
1114                         PIPE_UNLOCK(rpipe);
1115                         error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
1116                                         segsize, uio);
1117                         PIPE_LOCK(rpipe);
1118
1119                         if (error == 0 && segsize < size) {
1120                                 KASSERT(wpipe->pipe_buffer.in + segsize ==
1121                                         wpipe->pipe_buffer.size,
1122                                         ("Pipe buffer wraparound disappeared"));
1123                                 /*
1124                                  * Transfer remaining part now, to
1125                                  * support atomic writes.  Wraparound
1126                                  * happened.
1127                                  */
1128
1129                                 PIPE_UNLOCK(rpipe);
1130                                 error = uiomove(
1131                                     &wpipe->pipe_buffer.buffer[0],
1132                                     size - segsize, uio);
1133                                 PIPE_LOCK(rpipe);
1134                         }
1135                         if (error == 0) {
1136                                 wpipe->pipe_buffer.in += size;
1137                                 if (wpipe->pipe_buffer.in >=
1138                                     wpipe->pipe_buffer.size) {
1139                                         KASSERT(wpipe->pipe_buffer.in ==
1140                                                 size - segsize +
1141                                                 wpipe->pipe_buffer.size,
1142                                                 ("Expected wraparound bad"));
1143                                         wpipe->pipe_buffer.in = size - segsize;
1144                                 }
1145
1146                                 wpipe->pipe_buffer.cnt += size;
1147                                 KASSERT(wpipe->pipe_buffer.cnt <=
1148                                         wpipe->pipe_buffer.size,
1149                                         ("Pipe buffer overflow"));
1150                         }
1151                         pipeunlock(wpipe);
1152                         if (error != 0)
1153                                 break;
1154                 } else {
1155                         /*
1156                          * If the "read-side" has been blocked, wake it up now.
1157                          */
1158                         if (wpipe->pipe_state & PIPE_WANTR) {
1159                                 wpipe->pipe_state &= ~PIPE_WANTR;
1160                                 wakeup(wpipe);
1161                         }
1162
1163                         /*
1164                          * don't block on non-blocking I/O
1165                          */
1166                         if (fp->f_flag & FNONBLOCK) {
1167                                 error = EAGAIN;
1168                                 pipeunlock(wpipe);
1169                                 break;
1170                         }
1171
1172                         /*
1173                          * We have no more space and have something to offer,
1174                          * wake up select/poll.
1175                          */
1176                         pipeselwakeup(wpipe);
1177
1178                         wpipe->pipe_state |= PIPE_WANTW;
1179                         pipeunlock(wpipe);
1180                         error = msleep(wpipe, PIPE_MTX(rpipe),
1181                             PRIBIO | PCATCH, "pipewr", 0);
1182                         if (error != 0)
1183                                 break;
1184                 }
1185         }
1186
1187         pipelock(wpipe, 0);
1188         --wpipe->pipe_busy;
1189
1190         if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1191                 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1192                 wakeup(wpipe);
1193         } else if (wpipe->pipe_buffer.cnt > 0) {
1194                 /*
1195                  * If we have put any characters in the buffer, we wake up
1196                  * the reader.
1197                  */
1198                 if (wpipe->pipe_state & PIPE_WANTR) {
1199                         wpipe->pipe_state &= ~PIPE_WANTR;
1200                         wakeup(wpipe);
1201                 }
1202         }
1203
1204         /*
1205          * Don't return EPIPE if I/O was successful
1206          */
1207         if ((wpipe->pipe_buffer.cnt == 0) &&
1208             (uio->uio_resid == 0) &&
1209             (error == EPIPE)) {
1210                 error = 0;
1211         }
1212
1213         if (error == 0)
1214                 vfs_timestamp(&wpipe->pipe_mtime);
1215
1216         /*
1217          * We have something to offer,
1218          * wake up select/poll.
1219          */
1220         if (wpipe->pipe_buffer.cnt)
1221                 pipeselwakeup(wpipe);
1222
1223         pipeunlock(wpipe);
1224         PIPE_UNLOCK(rpipe);
1225         return (error);
1226 }
1227
1228 /* ARGSUSED */
1229 static int
1230 pipe_truncate(fp, length, active_cred, td)
1231         struct file *fp;
1232         off_t length;
1233         struct ucred *active_cred;
1234         struct thread *td;
1235 {
1236
1237         return (EINVAL);
1238 }
1239
1240 /*
1241  * we implement a very minimal set of ioctls for compatibility with sockets.
1242  */
1243 static int
1244 pipe_ioctl(fp, cmd, data, active_cred, td)
1245         struct file *fp;
1246         u_long cmd;
1247         void *data;
1248         struct ucred *active_cred;
1249         struct thread *td;
1250 {
1251         struct pipe *mpipe = fp->f_data;
1252         int error;
1253
1254         PIPE_LOCK(mpipe);
1255
1256 #ifdef MAC
1257         error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data);
1258         if (error) {
1259                 PIPE_UNLOCK(mpipe);
1260                 return (error);
1261         }
1262 #endif
1263
1264         error = 0;
1265         switch (cmd) {
1266
1267         case FIONBIO:
1268                 break;
1269
1270         case FIOASYNC:
1271                 if (*(int *)data) {
1272                         mpipe->pipe_state |= PIPE_ASYNC;
1273                 } else {
1274                         mpipe->pipe_state &= ~PIPE_ASYNC;
1275                 }
1276                 break;
1277
1278         case FIONREAD:
1279                 if (mpipe->pipe_state & PIPE_DIRECTW)
1280                         *(int *)data = mpipe->pipe_map.cnt;
1281                 else
1282                         *(int *)data = mpipe->pipe_buffer.cnt;
1283                 break;
1284
1285         case FIOSETOWN:
1286                 PIPE_UNLOCK(mpipe);
1287                 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
1288                 goto out_unlocked;
1289
1290         case FIOGETOWN:
1291                 *(int *)data = fgetown(&mpipe->pipe_sigio);
1292                 break;
1293
1294         /* This is deprecated, FIOSETOWN should be used instead. */
1295         case TIOCSPGRP:
1296                 PIPE_UNLOCK(mpipe);
1297                 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
1298                 goto out_unlocked;
1299
1300         /* This is deprecated, FIOGETOWN should be used instead. */
1301         case TIOCGPGRP:
1302                 *(int *)data = -fgetown(&mpipe->pipe_sigio);
1303                 break;
1304
1305         default:
1306                 error = ENOTTY;
1307                 break;
1308         }
1309         PIPE_UNLOCK(mpipe);
1310 out_unlocked:
1311         return (error);
1312 }
1313
1314 static int
1315 pipe_poll(fp, events, active_cred, td)
1316         struct file *fp;
1317         int events;
1318         struct ucred *active_cred;
1319         struct thread *td;
1320 {
1321         struct pipe *rpipe = fp->f_data;
1322         struct pipe *wpipe;
1323         int revents = 0;
1324 #ifdef MAC
1325         int error;
1326 #endif
1327
1328         wpipe = rpipe->pipe_peer;
1329         PIPE_LOCK(rpipe);
1330 #ifdef MAC
1331         error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair);
1332         if (error)
1333                 goto locked_error;
1334 #endif
1335         if (events & (POLLIN | POLLRDNORM))
1336                 if ((rpipe->pipe_state & PIPE_DIRECTW) ||
1337                     (rpipe->pipe_buffer.cnt > 0))
1338                         revents |= events & (POLLIN | POLLRDNORM);
1339
1340         if (events & (POLLOUT | POLLWRNORM))
1341                 if (wpipe->pipe_present != PIPE_ACTIVE ||
1342                     (wpipe->pipe_state & PIPE_EOF) ||
1343                     (((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
1344                      (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
1345                         revents |= events & (POLLOUT | POLLWRNORM);
1346
1347         if ((events & POLLINIGNEOF) == 0) {
1348                 if (rpipe->pipe_state & PIPE_EOF) {
1349                         revents |= (events & (POLLIN | POLLRDNORM));
1350                         if (wpipe->pipe_present != PIPE_ACTIVE ||
1351                             (wpipe->pipe_state & PIPE_EOF))
1352                                 revents |= POLLHUP;
1353                 }
1354         }
1355
1356         if (revents == 0) {
1357                 if (events & (POLLIN | POLLRDNORM)) {
1358                         selrecord(td, &rpipe->pipe_sel);
1359                         if (SEL_WAITING(&rpipe->pipe_sel))
1360                                 rpipe->pipe_state |= PIPE_SEL;
1361                 }
1362
1363                 if (events & (POLLOUT | POLLWRNORM)) {
1364                         selrecord(td, &wpipe->pipe_sel);
1365                         if (SEL_WAITING(&wpipe->pipe_sel))
1366                                 wpipe->pipe_state |= PIPE_SEL;
1367                 }
1368         }
1369 #ifdef MAC
1370 locked_error:
1371 #endif
1372         PIPE_UNLOCK(rpipe);
1373
1374         return (revents);
1375 }
1376
1377 /*
1378  * We shouldn't need locks here as we're doing a read and this should
1379  * be a natural race.
1380  */
1381 static int
1382 pipe_stat(fp, ub, active_cred, td)
1383         struct file *fp;
1384         struct stat *ub;
1385         struct ucred *active_cred;
1386         struct thread *td;
1387 {
1388         struct pipe *pipe = fp->f_data;
1389 #ifdef MAC
1390         int error;
1391
1392         PIPE_LOCK(pipe);
1393         error = mac_pipe_check_stat(active_cred, pipe->pipe_pair);
1394         PIPE_UNLOCK(pipe);
1395         if (error)
1396                 return (error);
1397 #endif
1398         bzero(ub, sizeof(*ub));
1399         ub->st_mode = S_IFIFO;
1400         ub->st_blksize = PAGE_SIZE;
1401         if (pipe->pipe_state & PIPE_DIRECTW)
1402                 ub->st_size = pipe->pipe_map.cnt;
1403         else
1404                 ub->st_size = pipe->pipe_buffer.cnt;
1405         ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
1406         ub->st_atim = pipe->pipe_atime;
1407         ub->st_mtim = pipe->pipe_mtime;
1408         ub->st_ctim = pipe->pipe_ctime;
1409         ub->st_uid = fp->f_cred->cr_uid;
1410         ub->st_gid = fp->f_cred->cr_gid;
1411         /*
1412          * Left as 0: st_dev, st_ino, st_nlink, st_rdev, st_flags, st_gen.
1413          * XXX (st_dev, st_ino) should be unique.
1414          */
1415         return (0);
1416 }
1417
1418 /* ARGSUSED */
1419 static int
1420 pipe_close(fp, td)
1421         struct file *fp;
1422         struct thread *td;
1423 {
1424         struct pipe *cpipe = fp->f_data;
1425
1426         fp->f_ops = &badfileops;
1427         fp->f_data = NULL;
1428         funsetown(&cpipe->pipe_sigio);
1429         pipeclose(cpipe);
1430         return (0);
1431 }
1432
1433 static void
1434 pipe_free_kmem(cpipe)
1435         struct pipe *cpipe;
1436 {
1437
1438         KASSERT(!mtx_owned(PIPE_MTX(cpipe)),
1439             ("pipe_free_kmem: pipe mutex locked"));
1440
1441         if (cpipe->pipe_buffer.buffer != NULL) {
1442                 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size);
1443                 vm_map_remove(pipe_map,
1444                     (vm_offset_t)cpipe->pipe_buffer.buffer,
1445                     (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size);
1446                 cpipe->pipe_buffer.buffer = NULL;
1447         }
1448 #ifndef PIPE_NODIRECT
1449         {
1450                 cpipe->pipe_map.cnt = 0;
1451                 cpipe->pipe_map.pos = 0;
1452                 cpipe->pipe_map.npages = 0;
1453         }
1454 #endif
1455 }
1456
1457 /*
1458  * shutdown the pipe
1459  */
1460 static void
1461 pipeclose(cpipe)
1462         struct pipe *cpipe;
1463 {
1464         struct pipepair *pp;
1465         struct pipe *ppipe;
1466
1467         KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL"));
1468
1469         PIPE_LOCK(cpipe);
1470         pipelock(cpipe, 0);
1471         pp = cpipe->pipe_pair;
1472
1473         pipeselwakeup(cpipe);
1474
1475         /*
1476          * If the other side is blocked, wake it up saying that
1477          * we want to close it down.
1478          */
1479         cpipe->pipe_state |= PIPE_EOF;
1480         while (cpipe->pipe_busy) {
1481                 wakeup(cpipe);
1482                 cpipe->pipe_state |= PIPE_WANT;
1483                 pipeunlock(cpipe);
1484                 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
1485                 pipelock(cpipe, 0);
1486         }
1487
1488
1489         /*
1490          * Disconnect from peer, if any.
1491          */
1492         ppipe = cpipe->pipe_peer;
1493         if (ppipe->pipe_present == PIPE_ACTIVE) {
1494                 pipeselwakeup(ppipe);
1495
1496                 ppipe->pipe_state |= PIPE_EOF;
1497                 wakeup(ppipe);
1498                 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0);
1499         }
1500
1501         /*
1502          * Mark this endpoint as free.  Release kmem resources.  We
1503          * don't mark this endpoint as unused until we've finished
1504          * doing that, or the pipe might disappear out from under
1505          * us.
1506          */
1507         PIPE_UNLOCK(cpipe);
1508         pipe_free_kmem(cpipe);
1509         PIPE_LOCK(cpipe);
1510         cpipe->pipe_present = PIPE_CLOSING;
1511         pipeunlock(cpipe);
1512
1513         /*
1514          * knlist_clear() may sleep dropping the PIPE_MTX. Set the
1515          * PIPE_FINALIZED, that allows other end to free the
1516          * pipe_pair, only after the knotes are completely dismantled.
1517          */
1518         knlist_clear(&cpipe->pipe_sel.si_note, 1);
1519         cpipe->pipe_present = PIPE_FINALIZED;
1520         seldrain(&cpipe->pipe_sel);
1521         knlist_destroy(&cpipe->pipe_sel.si_note);
1522
1523         /*
1524          * If both endpoints are now closed, release the memory for the
1525          * pipe pair.  If not, unlock.
1526          */
1527         if (ppipe->pipe_present == PIPE_FINALIZED) {
1528                 PIPE_UNLOCK(cpipe);
1529 #ifdef MAC
1530                 mac_pipe_destroy(pp);
1531 #endif
1532                 uma_zfree(pipe_zone, cpipe->pipe_pair);
1533         } else
1534                 PIPE_UNLOCK(cpipe);
1535 }
1536
1537 /*ARGSUSED*/
1538 static int
1539 pipe_kqfilter(struct file *fp, struct knote *kn)
1540 {
1541         struct pipe *cpipe;
1542
1543         cpipe = kn->kn_fp->f_data;
1544         PIPE_LOCK(cpipe);
1545         switch (kn->kn_filter) {
1546         case EVFILT_READ:
1547                 kn->kn_fop = &pipe_rfiltops;
1548                 break;
1549         case EVFILT_WRITE:
1550                 kn->kn_fop = &pipe_wfiltops;
1551                 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) {
1552                         /* other end of pipe has been closed */
1553                         PIPE_UNLOCK(cpipe);
1554                         return (EPIPE);
1555                 }
1556                 cpipe = cpipe->pipe_peer;
1557                 break;
1558         default:
1559                 PIPE_UNLOCK(cpipe);
1560                 return (EINVAL);
1561         }
1562
1563         knlist_add(&cpipe->pipe_sel.si_note, kn, 1);
1564         PIPE_UNLOCK(cpipe);
1565         return (0);
1566 }
1567
1568 static void
1569 filt_pipedetach(struct knote *kn)
1570 {
1571         struct pipe *cpipe = (struct pipe *)kn->kn_fp->f_data;
1572
1573         PIPE_LOCK(cpipe);
1574         if (kn->kn_filter == EVFILT_WRITE)
1575                 cpipe = cpipe->pipe_peer;
1576         knlist_remove(&cpipe->pipe_sel.si_note, kn, 1);
1577         PIPE_UNLOCK(cpipe);
1578 }
1579
1580 /*ARGSUSED*/
1581 static int
1582 filt_piperead(struct knote *kn, long hint)
1583 {
1584         struct pipe *rpipe = kn->kn_fp->f_data;
1585         struct pipe *wpipe = rpipe->pipe_peer;
1586         int ret;
1587
1588         PIPE_LOCK(rpipe);
1589         kn->kn_data = rpipe->pipe_buffer.cnt;
1590         if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
1591                 kn->kn_data = rpipe->pipe_map.cnt;
1592
1593         if ((rpipe->pipe_state & PIPE_EOF) ||
1594             wpipe->pipe_present != PIPE_ACTIVE ||
1595             (wpipe->pipe_state & PIPE_EOF)) {
1596                 kn->kn_flags |= EV_EOF;
1597                 PIPE_UNLOCK(rpipe);
1598                 return (1);
1599         }
1600         ret = kn->kn_data > 0;
1601         PIPE_UNLOCK(rpipe);
1602         return ret;
1603 }
1604
1605 /*ARGSUSED*/
1606 static int
1607 filt_pipewrite(struct knote *kn, long hint)
1608 {
1609         struct pipe *rpipe = kn->kn_fp->f_data;
1610         struct pipe *wpipe = rpipe->pipe_peer;
1611
1612         PIPE_LOCK(rpipe);
1613         if (wpipe->pipe_present != PIPE_ACTIVE ||
1614             (wpipe->pipe_state & PIPE_EOF)) {
1615                 kn->kn_data = 0;
1616                 kn->kn_flags |= EV_EOF;
1617                 PIPE_UNLOCK(rpipe);
1618                 return (1);
1619         }
1620         kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1621         if (wpipe->pipe_state & PIPE_DIRECTW)
1622                 kn->kn_data = 0;
1623
1624         PIPE_UNLOCK(rpipe);
1625         return (kn->kn_data >= PIPE_BUF);
1626 }