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/conf.h>
  97 #include <sys/fcntl.h>
  98 #include <sys/file.h>
  99 #include <sys/filedesc.h>
 100 #include <sys/filio.h>
 101 #include <sys/kernel.h>
 102 #include <sys/lock.h>
 103 #include <sys/mutex.h>
 104 #include <sys/ttycom.h>
 105 #include <sys/stat.h>
 106 #include <sys/malloc.h>
 107 #include <sys/poll.h>
 108 #include <sys/selinfo.h>
 109 #include <sys/signalvar.h>
 110 #include <sys/syscallsubr.h>
 111 #include <sys/sysctl.h>
 112 #include <sys/sysproto.h>
 113 #include <sys/pipe.h>
 114 #include <sys/proc.h>
 115 #include <sys/vnode.h>
 116 #include <sys/uio.h>
 117 #include <sys/event.h>
 118
 119 #include <security/mac/mac_framework.h>
 120
 121 #include <vm/vm.h>
 122 #include <vm/vm_param.h>
 123 #include <vm/vm_object.h>
 124 #include <vm/vm_kern.h>
 125 #include <vm/vm_extern.h>
 126 #include <vm/pmap.h>
 127 #include <vm/vm_map.h>
 128 #include <vm/vm_page.h>
 129 #include <vm/uma.h>
 130
 131 /*
 132  * Use this define if you want to disable *fancy* VM things.  Expect an
 133  * approx 30% decrease in transfer rate.  This could be useful for
 134  * NetBSD or OpenBSD.
 135  */
 136 /* #define PIPE_NODIRECT */
 137
 138 /*
 139  * interfaces to the outside world
 140  */
 141 static fo_rdwr_t        pipe_read;
 142 static fo_rdwr_t        pipe_write;
 143 static fo_truncate_t    pipe_truncate;
 144 static fo_ioctl_t       pipe_ioctl;
 145 static fo_poll_t        pipe_poll;
 146 static fo_kqfilter_t    pipe_kqfilter;
 147 static fo_stat_t        pipe_stat;
 148 static fo_close_t       pipe_close;
 149
 150 static struct fileops pipeops = {
 151         .fo_read = pipe_read,
 152         .fo_write = pipe_write,
 153         .fo_truncate = pipe_truncate,
 154         .fo_ioctl = pipe_ioctl,
 155         .fo_poll = pipe_poll,
 156         .fo_kqfilter = pipe_kqfilter,
 157         .fo_stat = pipe_stat,
 158         .fo_close = pipe_close,
 159         .fo_chmod = invfo_chmod,
 160         .fo_chown = invfo_chown,
 161         .fo_flags = DFLAG_PASSABLE
 162 };
 163
 164 static void     filt_pipedetach(struct knote *kn);
 165 static int      filt_piperead(struct knote *kn, long hint);
 166 static int      filt_pipewrite(struct knote *kn, long hint);
 167
 168 static struct filterops pipe_rfiltops = {
 169         .f_isfd = 1,
 170         .f_detach = filt_pipedetach,
 171         .f_event = filt_piperead
 172 };
 173 static struct filterops pipe_wfiltops = {
 174         .f_isfd = 1,
 175         .f_detach = filt_pipedetach,
 176         .f_event = filt_pipewrite
 177 };
 178
 179 /*
 180  * Default pipe buffer size(s), this can be kind-of large now because pipe
 181  * space is pageable.  The pipe code will try to maintain locality of
 182  * reference for performance reasons, so small amounts of outstanding I/O
 183  * will not wipe the cache.
 184  */
 185 #define MINPIPESIZE (PIPE_SIZE/3)
 186 #define MAXPIPESIZE (2*PIPE_SIZE/3)
 187
 188 static long amountpipekva;
 189 static int pipefragretry;
 190 static int pipeallocfail;
 191 static int piperesizefail;
 192 static int piperesizeallowed = 1;
 193
 194 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN,
 195            &maxpipekva, 0, "Pipe KVA limit");
 196 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD,
 197            &amountpipekva, 0, "Pipe KVA usage");
 198 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD,
 199           &pipefragretry, 0, "Pipe allocation retries due to fragmentation");
 200 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD,
 201           &pipeallocfail, 0, "Pipe allocation failures");
 202 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD,
 203           &piperesizefail, 0, "Pipe resize failures");
 204 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW,
 205           &piperesizeallowed, 0, "Pipe resizing allowed");
 206
 207 static void pipeinit(void *dummy __unused);
 208 static void pipeclose(struct pipe *cpipe);
 209 static void pipe_free_kmem(struct pipe *cpipe);
 210 static int pipe_create(struct pipe *pipe, int backing);
 211 static __inline int pipelock(struct pipe *cpipe, int catch);
 212 static __inline void pipeunlock(struct pipe *cpipe);
 213 static __inline void pipeselwakeup(struct pipe *cpipe);
 214 #ifndef PIPE_NODIRECT
 215 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio);
 216 static void pipe_destroy_write_buffer(struct pipe *wpipe);
 217 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio);
 218 static void pipe_clone_write_buffer(struct pipe *wpipe);
 219 #endif
 220 static int pipespace(struct pipe *cpipe, int size);
 221 static int pipespace_new(struct pipe *cpipe, int size);
 222
 223 static int      pipe_zone_ctor(void *mem, int size, void *arg, int flags);
 224 static int      pipe_zone_init(void *mem, int size, int flags);
 225 static void     pipe_zone_fini(void *mem, int size);
 226
 227 static uma_zone_t pipe_zone;
 228 static struct unrhdr *pipeino_unr;
 229 static dev_t pipedev_ino;
 230
 231 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
 232
 233 static void
 234 pipeinit(void *dummy __unused)
 235 {
 236
 237         pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair),
 238             pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini,
 239             UMA_ALIGN_PTR, 0);
 240         KASSERT(pipe_zone != NULL, ("pipe_zone not initialized"));
 241         pipeino_unr = new_unrhdr(1, INT32_MAX, NULL);
 242         KASSERT(pipeino_unr != NULL, ("pipe fake inodes not initialized"));
 243         pipedev_ino = devfs_alloc_cdp_inode();
 244         KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized"));
 245 }
 246
 247 static int
 248 pipe_zone_ctor(void *mem, int size, void *arg, int flags)
 249 {
 250         struct pipepair *pp;
 251         struct pipe *rpipe, *wpipe;
 252
 253         KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size"));
 254
 255         pp = (struct pipepair *)mem;
 256
 257         /*
 258          * We zero both pipe endpoints to make sure all the kmem pointers
 259          * are NULL, flag fields are zero'd, etc.  We timestamp both
 260          * endpoints with the same time.
 261          */
 262         rpipe = &pp->pp_rpipe;
 263         bzero(rpipe, sizeof(*rpipe));
 264         vfs_timestamp(&rpipe->pipe_ctime);
 265         rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime;
 266
 267         wpipe = &pp->pp_wpipe;
 268         bzero(wpipe, sizeof(*wpipe));
 269         wpipe->pipe_ctime = rpipe->pipe_ctime;
 270         wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime;
 271
 272         rpipe->pipe_peer = wpipe;
 273         rpipe->pipe_pair = pp;
 274         wpipe->pipe_peer = rpipe;
 275         wpipe->pipe_pair = pp;
 276
 277         /*
 278          * Mark both endpoints as present; they will later get free'd
 279          * one at a time.  When both are free'd, then the whole pair
 280          * is released.
 281          */
 282         rpipe->pipe_present = PIPE_ACTIVE;
 283         wpipe->pipe_present = PIPE_ACTIVE;
 284
 285         /*
 286          * Eventually, the MAC Framework may initialize the label
 287          * in ctor or init, but for now we do it elswhere to avoid
 288          * blocking in ctor or init.
 289          */
 290         pp->pp_label = NULL;
 291
 292         return (0);
 293 }
 294
 295 static int
 296 pipe_zone_init(void *mem, int size, int flags)
 297 {
 298         struct pipepair *pp;
 299
 300         KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size"));
 301
 302         pp = (struct pipepair *)mem;
 303
 304         mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_RECURSE);
 305         return (0);
 306 }
 307
 308 static void
 309 pipe_zone_fini(void *mem, int size)
 310 {
 311         struct pipepair *pp;
 312
 313         KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size"));
 314
 315         pp = (struct pipepair *)mem;
 316
 317         mtx_destroy(&pp->pp_mtx);
 318 }
 319
 320 /*
 321  * The pipe system call for the DTYPE_PIPE type of pipes.  If we fail, let
 322  * the zone pick up the pieces via pipeclose().
 323  */
 324 int
 325 kern_pipe(struct thread *td, int fildes[2])
 326 {
 327         struct filedesc *fdp = td->td_proc->p_fd;
 328         struct file *rf, *wf;
 329         struct pipepair *pp;
 330         struct pipe *rpipe, *wpipe;
 331         int fd, error;
 332
 333         pp = uma_zalloc(pipe_zone, M_WAITOK);
 334 #ifdef MAC
 335         /*
 336          * The MAC label is shared between the connected endpoints.  As a
 337          * result mac_pipe_init() and mac_pipe_create() are called once
 338          * for the pair, and not on the endpoints.
 339          */
 340         mac_pipe_init(pp);
 341         mac_pipe_create(td->td_ucred, pp);
 342 #endif
 343         rpipe = &pp->pp_rpipe;
 344         wpipe = &pp->pp_wpipe;
 345
 346         knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe));
 347         knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe));
 348
 349         /* Only the forward direction pipe is backed by default */
 350         if ((error = pipe_create(rpipe, 1)) != 0 ||
 351             (error = pipe_create(wpipe, 0)) != 0) {
 352                 pipeclose(rpipe);
 353                 pipeclose(wpipe);
 354                 return (error);
 355         }
 356
 357         rpipe->pipe_state |= PIPE_DIRECTOK;
 358         wpipe->pipe_state |= PIPE_DIRECTOK;
 359
 360         error = falloc(td, &rf, &fd, 0);
 361         if (error) {
 362                 pipeclose(rpipe);
 363                 pipeclose(wpipe);
 364                 return (error);
 365         }
 366         /* An extra reference on `rf' has been held for us by falloc(). */
 367         fildes[0] = fd;
 368
 369         /*
 370          * Warning: once we've gotten past allocation of the fd for the
 371          * read-side, we can only drop the read side via fdrop() in order
 372          * to avoid races against processes which manage to dup() the read
 373          * side while we are blocked trying to allocate the write side.
 374          */
 375         finit(rf, FREAD | FWRITE, DTYPE_PIPE, rpipe, &pipeops);
 376         error = falloc(td, &wf, &fd, 0);
 377         if (error) {
 378                 fdclose(fdp, rf, fildes[0], td);
 379                 fdrop(rf, td);
 380                 /* rpipe has been closed by fdrop(). */
 381                 pipeclose(wpipe);
 382                 return (error);
 383         }
 384         /* An extra reference on `wf' has been held for us by falloc(). */
 385         finit(wf, FREAD | FWRITE, DTYPE_PIPE, wpipe, &pipeops);
 386         fdrop(wf, td);
 387         fildes[1] = fd;
 388         fdrop(rf, td);
 389
 390         return (0);
 391 }
 392
 393 /* ARGSUSED */
 394 int
 395 sys_pipe(struct thread *td, struct pipe_args *uap)
 396 {
 397         int error;
 398         int fildes[2];
 399
 400         error = kern_pipe(td, fildes);
 401         if (error)
 402                 return (error);
 403
 404         td->td_retval[0] = fildes[0];
 405         td->td_retval[1] = fildes[1];
 406
 407         return (0);
 408 }
 409
 410 /*
 411  * Allocate kva for pipe circular buffer, the space is pageable
 412  * This routine will 'realloc' the size of a pipe safely, if it fails
 413  * it will retain the old buffer.
 414  * If it fails it will return ENOMEM.
 415  */
 416 static int
 417 pipespace_new(cpipe, size)
 418         struct pipe *cpipe;
 419         int size;
 420 {
 421         caddr_t buffer;
 422         int error, cnt, firstseg;
 423         static int curfail = 0;
 424         static struct timeval lastfail;
 425
 426         KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked"));
 427         KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW),
 428                 ("pipespace: resize of direct writes not allowed"));
 429 retry:
 430         cnt = cpipe->pipe_buffer.cnt;
 431         if (cnt > size)
 432                 size = cnt;
 433
 434         size = round_page(size);
 435         buffer = (caddr_t) vm_map_min(pipe_map);
 436
 437         error = vm_map_find(pipe_map, NULL, 0,
 438                 (vm_offset_t *) &buffer, size, 1,
 439                 VM_PROT_ALL, VM_PROT_ALL, 0);
 440         if (error != KERN_SUCCESS) {
 441                 if ((cpipe->pipe_buffer.buffer == NULL) &&
 442                         (size > SMALL_PIPE_SIZE)) {
 443                         size = SMALL_PIPE_SIZE;
 444                         pipefragretry++;
 445                         goto retry;
 446                 }
 447                 if (cpipe->pipe_buffer.buffer == NULL) {
 448                         pipeallocfail++;
 449                         if (ppsratecheck(&lastfail, &curfail, 1))
 450                                 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n");
 451                 } else {
 452                         piperesizefail++;
 453                 }
 454                 return (ENOMEM);
 455         }
 456
 457         /* copy data, then free old resources if we're resizing */
 458         if (cnt > 0) {
 459                 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) {
 460                         firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out;
 461                         bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
 462                                 buffer, firstseg);
 463                         if ((cnt - firstseg) > 0)
 464                                 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg],
 465                                         cpipe->pipe_buffer.in);
 466                 } else {
 467                         bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
 468                                 buffer, cnt);
 469                 }
 470         }
 471         pipe_free_kmem(cpipe);
 472         cpipe->pipe_buffer.buffer = buffer;
 473         cpipe->pipe_buffer.size = size;
 474         cpipe->pipe_buffer.in = cnt;
 475         cpipe->pipe_buffer.out = 0;
 476         cpipe->pipe_buffer.cnt = cnt;
 477         atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size);
 478         return (0);
 479 }
 480
 481 /*
 482  * Wrapper for pipespace_new() that performs locking assertions.
 483  */
 484 static int
 485 pipespace(cpipe, size)
 486         struct pipe *cpipe;
 487         int size;
 488 {
 489
 490         KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
 491                 ("Unlocked pipe passed to pipespace"));
 492         return (pipespace_new(cpipe, size));
 493 }
 494
 495 /*
 496  * lock a pipe for I/O, blocking other access
 497  */
 498 static __inline int
 499 pipelock(cpipe, catch)
 500         struct pipe *cpipe;
 501         int catch;
 502 {
 503         int error;
 504
 505         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 506         while (cpipe->pipe_state & PIPE_LOCKFL) {
 507                 cpipe->pipe_state |= PIPE_LWANT;
 508                 error = msleep(cpipe, PIPE_MTX(cpipe),
 509                     catch ? (PRIBIO | PCATCH) : PRIBIO,
 510                     "pipelk", 0);
 511                 if (error != 0)
 512                         return (error);
 513         }
 514         cpipe->pipe_state |= PIPE_LOCKFL;
 515         return (0);
 516 }
 517
 518 /*
 519  * unlock a pipe I/O lock
 520  */
 521 static __inline void
 522 pipeunlock(cpipe)
 523         struct pipe *cpipe;
 524 {
 525
 526         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 527         KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
 528                 ("Unlocked pipe passed to pipeunlock"));
 529         cpipe->pipe_state &= ~PIPE_LOCKFL;
 530         if (cpipe->pipe_state & PIPE_LWANT) {
 531                 cpipe->pipe_state &= ~PIPE_LWANT;
 532                 wakeup(cpipe);
 533         }
 534 }
 535
 536 static __inline void
 537 pipeselwakeup(cpipe)
 538         struct pipe *cpipe;
 539 {
 540
 541         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 542         if (cpipe->pipe_state & PIPE_SEL) {
 543                 selwakeuppri(&cpipe->pipe_sel, PSOCK);
 544                 if (!SEL_WAITING(&cpipe->pipe_sel))
 545                         cpipe->pipe_state &= ~PIPE_SEL;
 546         }
 547         if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
 548                 pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
 549         KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0);
 550 }
 551
 552 /*
 553  * Initialize and allocate VM and memory for pipe.  The structure
 554  * will start out zero'd from the ctor, so we just manage the kmem.
 555  */
 556 static int
 557 pipe_create(pipe, backing)
 558         struct pipe *pipe;
 559         int backing;
 560 {
 561         int error;
 562
 563         if (backing) {
 564                 if (amountpipekva > maxpipekva / 2)
 565                         error = pipespace_new(pipe, SMALL_PIPE_SIZE);
 566                 else
 567                         error = pipespace_new(pipe, PIPE_SIZE);
 568         } else {
 569                 /* If we're not backing this pipe, no need to do anything. */
 570                 error = 0;
 571         }
 572         if (error == 0) {
 573                 pipe->pipe_ino = alloc_unr(pipeino_unr);
 574                 if (pipe->pipe_ino == -1)
 575                         /* pipeclose will clear allocated kva */
 576                         error = ENOMEM;
 577         }
 578         return (error);
 579 }
 580
 581 /* ARGSUSED */
 582 static int
 583 pipe_read(fp, uio, active_cred, flags, td)
 584         struct file *fp;
 585         struct uio *uio;
 586         struct ucred *active_cred;
 587         struct thread *td;
 588         int flags;
 589 {
 590         struct pipe *rpipe = fp->f_data;
 591         int error;
 592         int nread = 0;
 593         u_int size;
 594
 595         PIPE_LOCK(rpipe);
 596         ++rpipe->pipe_busy;
 597         error = pipelock(rpipe, 1);
 598         if (error)
 599                 goto unlocked_error;
 600
 601 #ifdef MAC
 602         error = mac_pipe_check_read(active_cred, rpipe->pipe_pair);
 603         if (error)
 604                 goto locked_error;
 605 #endif
 606         if (amountpipekva > (3 * maxpipekva) / 4) {
 607                 if (!(rpipe->pipe_state & PIPE_DIRECTW) &&
 608                         (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
 609                         (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
 610                         (piperesizeallowed == 1)) {
 611                         PIPE_UNLOCK(rpipe);
 612                         pipespace(rpipe, SMALL_PIPE_SIZE);
 613                         PIPE_LOCK(rpipe);
 614                 }
 615         }
 616
 617         while (uio->uio_resid) {
 618                 /*
 619                  * normal pipe buffer receive
 620                  */
 621                 if (rpipe->pipe_buffer.cnt > 0) {
 622                         size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
 623                         if (size > rpipe->pipe_buffer.cnt)
 624                                 size = rpipe->pipe_buffer.cnt;
 625                         if (size > (u_int) uio->uio_resid)
 626                                 size = (u_int) uio->uio_resid;
 627
 628                         PIPE_UNLOCK(rpipe);
 629                         error = uiomove(
 630                             &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
 631                             size, uio);
 632                         PIPE_LOCK(rpipe);
 633                         if (error)
 634                                 break;
 635
 636                         rpipe->pipe_buffer.out += size;
 637                         if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
 638                                 rpipe->pipe_buffer.out = 0;
 639
 640                         rpipe->pipe_buffer.cnt -= size;
 641
 642                         /*
 643                          * If there is no more to read in the pipe, reset
 644                          * its pointers to the beginning.  This improves
 645                          * cache hit stats.
 646                          */
 647                         if (rpipe->pipe_buffer.cnt == 0) {
 648                                 rpipe->pipe_buffer.in = 0;
 649                                 rpipe->pipe_buffer.out = 0;
 650                         }
 651                         nread += size;
 652 #ifndef PIPE_NODIRECT
 653                 /*
 654                  * Direct copy, bypassing a kernel buffer.
 655                  */
 656                 } else if ((size = rpipe->pipe_map.cnt) &&
 657                            (rpipe->pipe_state & PIPE_DIRECTW)) {
 658                         if (size > (u_int) uio->uio_resid)
 659                                 size = (u_int) uio->uio_resid;
 660
 661                         PIPE_UNLOCK(rpipe);
 662                         error = uiomove_fromphys(rpipe->pipe_map.ms,
 663                             rpipe->pipe_map.pos, size, uio);
 664                         PIPE_LOCK(rpipe);
 665                         if (error)
 666                                 break;
 667                         nread += size;
 668                         rpipe->pipe_map.pos += size;
 669                         rpipe->pipe_map.cnt -= size;
 670                         if (rpipe->pipe_map.cnt == 0) {
 671                                 rpipe->pipe_state &= ~PIPE_DIRECTW;
 672                                 wakeup(rpipe);
 673                         }
 674 #endif
 675                 } else {
 676                         /*
 677                          * detect EOF condition
 678                          * read returns 0 on EOF, no need to set error
 679                          */
 680                         if (rpipe->pipe_state & PIPE_EOF)
 681                                 break;
 682
 683                         /*
 684                          * If the "write-side" has been blocked, wake it up now.
 685                          */
 686                         if (rpipe->pipe_state & PIPE_WANTW) {
 687                                 rpipe->pipe_state &= ~PIPE_WANTW;
 688                                 wakeup(rpipe);
 689                         }
 690
 691                         /*
 692                          * Break if some data was read.
 693                          */
 694                         if (nread > 0)
 695                                 break;
 696
 697                         /*
 698                          * Unlock the pipe buffer for our remaining processing.
 699                          * We will either break out with an error or we will
 700                          * sleep and relock to loop.
 701                          */
 702                         pipeunlock(rpipe);
 703
 704                         /*
 705                          * Handle non-blocking mode operation or
 706                          * wait for more data.
 707                          */
 708                         if (fp->f_flag & FNONBLOCK) {
 709                                 error = EAGAIN;
 710                         } else {
 711                                 rpipe->pipe_state |= PIPE_WANTR;
 712                                 if ((error = msleep(rpipe, PIPE_MTX(rpipe),
 713                                     PRIBIO | PCATCH,
 714                                     "piperd", 0)) == 0)
 715                                         error = pipelock(rpipe, 1);
 716                         }
 717                         if (error)
 718                                 goto unlocked_error;
 719                 }
 720         }
 721 #ifdef MAC
 722 locked_error:
 723 #endif
 724         pipeunlock(rpipe);
 725
 726         /* XXX: should probably do this before getting any locks. */
 727         if (error == 0)
 728                 vfs_timestamp(&rpipe->pipe_atime);
 729 unlocked_error:
 730         --rpipe->pipe_busy;
 731
 732         /*
 733          * PIPE_WANT processing only makes sense if pipe_busy is 0.
 734          */
 735         if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
 736                 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
 737                 wakeup(rpipe);
 738         } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
 739                 /*
 740                  * Handle write blocking hysteresis.
 741                  */
 742                 if (rpipe->pipe_state & PIPE_WANTW) {
 743                         rpipe->pipe_state &= ~PIPE_WANTW;
 744                         wakeup(rpipe);
 745                 }
 746         }
 747
 748         if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
 749                 pipeselwakeup(rpipe);
 750
 751         PIPE_UNLOCK(rpipe);
 752         return (error);
 753 }
 754
 755 #ifndef PIPE_NODIRECT
 756 /*
 757  * Map the sending processes' buffer into kernel space and wire it.
 758  * This is similar to a physical write operation.
 759  */
 760 static int
 761 pipe_build_write_buffer(wpipe, uio)
 762         struct pipe *wpipe;
 763         struct uio *uio;
 764 {
 765         u_int size;
 766         int i;
 767
 768         PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED);
 769         KASSERT(wpipe->pipe_state & PIPE_DIRECTW,
 770                 ("Clone attempt on non-direct write pipe!"));
 771
 772         size = (u_int) uio->uio_iov->iov_len;
 773         if (size > wpipe->pipe_buffer.size)
 774                 size = wpipe->pipe_buffer.size;
 775
 776         if ((i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
 777             (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ,
 778             wpipe->pipe_map.ms, PIPENPAGES)) < 0)
 779                 return (EFAULT);
 780
 781 /*
 782  * set up the control block
 783  */
 784         wpipe->pipe_map.npages = i;
 785         wpipe->pipe_map.pos =
 786             ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK;
 787         wpipe->pipe_map.cnt = size;
 788
 789 /*
 790  * and update the uio data
 791  */
 792
 793         uio->uio_iov->iov_len -= size;
 794         uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size;
 795         if (uio->uio_iov->iov_len == 0)
 796                 uio->uio_iov++;
 797         uio->uio_resid -= size;
 798         uio->uio_offset += size;
 799         return (0);
 800 }
 801
 802 /*
 803  * unmap and unwire the process buffer
 804  */
 805 static void
 806 pipe_destroy_write_buffer(wpipe)
 807         struct pipe *wpipe;
 808 {
 809
 810         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 811         vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages);
 812         wpipe->pipe_map.npages = 0;
 813 }
 814
 815 /*
 816  * In the case of a signal, the writing process might go away.  This
 817  * code copies the data into the circular buffer so that the source
 818  * pages can be freed without loss of data.
 819  */
 820 static void
 821 pipe_clone_write_buffer(wpipe)
 822         struct pipe *wpipe;
 823 {
 824         struct uio uio;
 825         struct iovec iov;
 826         int size;
 827         int pos;
 828
 829         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 830         size = wpipe->pipe_map.cnt;
 831         pos = wpipe->pipe_map.pos;
 832
 833         wpipe->pipe_buffer.in = size;
 834         wpipe->pipe_buffer.out = 0;
 835         wpipe->pipe_buffer.cnt = size;
 836         wpipe->pipe_state &= ~PIPE_DIRECTW;
 837
 838         PIPE_UNLOCK(wpipe);
 839         iov.iov_base = wpipe->pipe_buffer.buffer;
 840         iov.iov_len = size;
 841         uio.uio_iov = &iov;
 842         uio.uio_iovcnt = 1;
 843         uio.uio_offset = 0;
 844         uio.uio_resid = size;
 845         uio.uio_segflg = UIO_SYSSPACE;
 846         uio.uio_rw = UIO_READ;
 847         uio.uio_td = curthread;
 848         uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio);
 849         PIPE_LOCK(wpipe);
 850         pipe_destroy_write_buffer(wpipe);
 851 }
 852
 853 /*
 854  * This implements the pipe buffer write mechanism.  Note that only
 855  * a direct write OR a normal pipe write can be pending at any given time.
 856  * If there are any characters in the pipe buffer, the direct write will
 857  * be deferred until the receiving process grabs all of the bytes from
 858  * the pipe buffer.  Then the direct mapping write is set-up.
 859  */
 860 static int
 861 pipe_direct_write(wpipe, uio)
 862         struct pipe *wpipe;
 863         struct uio *uio;
 864 {
 865         int error;
 866
 867 retry:
 868         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 869         error = pipelock(wpipe, 1);
 870         if (wpipe->pipe_state & PIPE_EOF)
 871                 error = EPIPE;
 872         if (error) {
 873                 pipeunlock(wpipe);
 874                 goto error1;
 875         }
 876         while (wpipe->pipe_state & PIPE_DIRECTW) {
 877                 if (wpipe->pipe_state & PIPE_WANTR) {
 878                         wpipe->pipe_state &= ~PIPE_WANTR;
 879                         wakeup(wpipe);
 880                 }
 881                 pipeselwakeup(wpipe);
 882                 wpipe->pipe_state |= PIPE_WANTW;
 883                 pipeunlock(wpipe);
 884                 error = msleep(wpipe, PIPE_MTX(wpipe),
 885                     PRIBIO | PCATCH, "pipdww", 0);
 886                 if (error)
 887                         goto error1;
 888                 else
 889                         goto retry;
 890         }
 891         wpipe->pipe_map.cnt = 0;        /* transfer not ready yet */
 892         if (wpipe->pipe_buffer.cnt > 0) {
 893                 if (wpipe->pipe_state & PIPE_WANTR) {
 894                         wpipe->pipe_state &= ~PIPE_WANTR;
 895                         wakeup(wpipe);
 896                 }
 897                 pipeselwakeup(wpipe);
 898                 wpipe->pipe_state |= PIPE_WANTW;
 899                 pipeunlock(wpipe);
 900                 error = msleep(wpipe, PIPE_MTX(wpipe),
 901                     PRIBIO | PCATCH, "pipdwc", 0);
 902                 if (error)
 903                         goto error1;
 904                 else
 905                         goto retry;
 906         }
 907
 908         wpipe->pipe_state |= PIPE_DIRECTW;
 909
 910         PIPE_UNLOCK(wpipe);
 911         error = pipe_build_write_buffer(wpipe, uio);
 912         PIPE_LOCK(wpipe);
 913         if (error) {
 914                 wpipe->pipe_state &= ~PIPE_DIRECTW;
 915                 pipeunlock(wpipe);
 916                 goto error1;
 917         }
 918
 919         error = 0;
 920         while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
 921                 if (wpipe->pipe_state & PIPE_EOF) {
 922                         pipe_destroy_write_buffer(wpipe);
 923                         pipeselwakeup(wpipe);
 924                         pipeunlock(wpipe);
 925                         error = EPIPE;
 926                         goto error1;
 927                 }
 928                 if (wpipe->pipe_state & PIPE_WANTR) {
 929                         wpipe->pipe_state &= ~PIPE_WANTR;
 930                         wakeup(wpipe);
 931                 }
 932                 pipeselwakeup(wpipe);
 933                 pipeunlock(wpipe);
 934                 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
 935                     "pipdwt", 0);
 936                 pipelock(wpipe, 0);
 937         }
 938
 939         if (wpipe->pipe_state & PIPE_EOF)
 940                 error = EPIPE;
 941         if (wpipe->pipe_state & PIPE_DIRECTW) {
 942                 /*
 943                  * this bit of trickery substitutes a kernel buffer for
 944                  * the process that might be going away.
 945                  */
 946                 pipe_clone_write_buffer(wpipe);
 947         } else {
 948                 pipe_destroy_write_buffer(wpipe);
 949         }
 950         pipeunlock(wpipe);
 951         return (error);
 952
 953 error1:
 954         wakeup(wpipe);
 955         return (error);
 956 }
 957 #endif
 958
 959 static int
 960 pipe_write(fp, uio, active_cred, flags, td)
 961         struct file *fp;
 962         struct uio *uio;
 963         struct ucred *active_cred;
 964         struct thread *td;
 965         int flags;
 966 {
 967         int error = 0;
 968         int desiredsize, orig_resid;
 969         struct pipe *wpipe, *rpipe;
 970
 971         rpipe = fp->f_data;
 972         wpipe = rpipe->pipe_peer;
 973
 974         PIPE_LOCK(rpipe);
 975         error = pipelock(wpipe, 1);
 976         if (error) {
 977                 PIPE_UNLOCK(rpipe);
 978                 return (error);
 979         }
 980         /*
 981          * detect loss of pipe read side, issue SIGPIPE if lost.
 982          */
 983         if (wpipe->pipe_present != PIPE_ACTIVE ||
 984             (wpipe->pipe_state & PIPE_EOF)) {
 985                 pipeunlock(wpipe);
 986                 PIPE_UNLOCK(rpipe);
 987                 return (EPIPE);
 988         }
 989 #ifdef MAC
 990         error = mac_pipe_check_write(active_cred, wpipe->pipe_pair);
 991         if (error) {
 992                 pipeunlock(wpipe);
 993                 PIPE_UNLOCK(rpipe);
 994                 return (error);
 995         }
 996 #endif
 997         ++wpipe->pipe_busy;
 998
 999         /* Choose a larger size if it's advantageous */
1000         desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size);
1001         while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) {
1002                 if (piperesizeallowed != 1)
1003                         break;
1004                 if (amountpipekva > maxpipekva / 2)
1005                         break;
1006                 if (desiredsize == BIG_PIPE_SIZE)
1007                         break;
1008                 desiredsize = desiredsize * 2;
1009         }
1010
1011         /* Choose a smaller size if we're in a OOM situation */
1012         if ((amountpipekva > (3 * maxpipekva) / 4) &&
1013                 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
1014                 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
1015                 (piperesizeallowed == 1))
1016                 desiredsize = SMALL_PIPE_SIZE;
1017
1018         /* Resize if the above determined that a new size was necessary */
1019         if ((desiredsize != wpipe->pipe_buffer.size) &&
1020                 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) {
1021                 PIPE_UNLOCK(wpipe);
1022                 pipespace(wpipe, desiredsize);
1023                 PIPE_LOCK(wpipe);
1024         }
1025         if (wpipe->pipe_buffer.size == 0) {
1026                 /*
1027                  * This can only happen for reverse direction use of pipes
1028                  * in a complete OOM situation.
1029                  */
1030                 error = ENOMEM;
1031                 --wpipe->pipe_busy;
1032                 pipeunlock(wpipe);
1033                 PIPE_UNLOCK(wpipe);
1034                 return (error);
1035         }
1036
1037         pipeunlock(wpipe);
1038
1039         orig_resid = uio->uio_resid;
1040
1041         while (uio->uio_resid) {
1042                 int space;
1043
1044                 pipelock(wpipe, 0);
1045                 if (wpipe->pipe_state & PIPE_EOF) {
1046                         pipeunlock(wpipe);
1047                         error = EPIPE;
1048                         break;
1049                 }
1050 #ifndef PIPE_NODIRECT
1051                 /*
1052                  * If the transfer is large, we can gain performance if
1053                  * we do process-to-process copies directly.
1054                  * If the write is non-blocking, we don't use the
1055                  * direct write mechanism.
1056                  *
1057                  * The direct write mechanism will detect the reader going
1058                  * away on us.
1059                  */
1060                 if (uio->uio_segflg == UIO_USERSPACE &&
1061                     uio->uio_iov->iov_len >= PIPE_MINDIRECT &&
1062                     wpipe->pipe_buffer.size >= PIPE_MINDIRECT &&
1063                     (fp->f_flag & FNONBLOCK) == 0) {
1064                         pipeunlock(wpipe);
1065                         error = pipe_direct_write(wpipe, uio);
1066                         if (error)
1067                                 break;
1068                         continue;
1069                 }
1070 #endif
1071
1072                 /*
1073                  * Pipe buffered writes cannot be coincidental with
1074                  * direct writes.  We wait until the currently executing
1075                  * direct write is completed before we start filling the
1076                  * pipe buffer.  We break out if a signal occurs or the
1077                  * reader goes away.
1078                  */
1079                 if (wpipe->pipe_state & PIPE_DIRECTW) {
1080                         if (wpipe->pipe_state & PIPE_WANTR) {
1081                                 wpipe->pipe_state &= ~PIPE_WANTR;
1082                                 wakeup(wpipe);
1083                         }
1084                         pipeselwakeup(wpipe);
1085                         wpipe->pipe_state |= PIPE_WANTW;
1086                         pipeunlock(wpipe);
1087                         error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH,
1088                             "pipbww", 0);
1089                         if (error)
1090                                 break;
1091                         else
1092                                 continue;
1093                 }
1094
1095                 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1096
1097                 /* Writes of size <= PIPE_BUF must be atomic. */
1098                 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
1099                         space = 0;
1100
1101                 if (space > 0) {
1102                         int size;       /* Transfer size */
1103                         int segsize;    /* first segment to transfer */
1104
1105                         /*
1106                          * Transfer size is minimum of uio transfer
1107                          * and free space in pipe buffer.
1108                          */
1109                         if (space > uio->uio_resid)
1110                                 size = uio->uio_resid;
1111                         else
1112                                 size = space;
1113                         /*
1114                          * First segment to transfer is minimum of
1115                          * transfer size and contiguous space in
1116                          * pipe buffer.  If first segment to transfer
1117                          * is less than the transfer size, we've got
1118                          * a wraparound in the buffer.
1119                          */
1120                         segsize = wpipe->pipe_buffer.size -
1121                                 wpipe->pipe_buffer.in;
1122                         if (segsize > size)
1123                                 segsize = size;
1124
1125                         /* Transfer first segment */
1126
1127                         PIPE_UNLOCK(rpipe);
1128                         error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
1129                                         segsize, uio);
1130                         PIPE_LOCK(rpipe);
1131
1132                         if (error == 0 && segsize < size) {
1133                                 KASSERT(wpipe->pipe_buffer.in + segsize ==
1134                                         wpipe->pipe_buffer.size,
1135                                         ("Pipe buffer wraparound disappeared"));
1136                                 /*
1137                                  * Transfer remaining part now, to
1138                                  * support atomic writes.  Wraparound
1139                                  * happened.
1140                                  */
1141
1142                                 PIPE_UNLOCK(rpipe);
1143                                 error = uiomove(
1144                                     &wpipe->pipe_buffer.buffer[0],
1145                                     size - segsize, uio);
1146                                 PIPE_LOCK(rpipe);
1147                         }
1148                         if (error == 0) {
1149                                 wpipe->pipe_buffer.in += size;
1150                                 if (wpipe->pipe_buffer.in >=
1151                                     wpipe->pipe_buffer.size) {
1152                                         KASSERT(wpipe->pipe_buffer.in ==
1153                                                 size - segsize +
1154                                                 wpipe->pipe_buffer.size,
1155                                                 ("Expected wraparound bad"));
1156                                         wpipe->pipe_buffer.in = size - segsize;
1157                                 }
1158
1159                                 wpipe->pipe_buffer.cnt += size;
1160                                 KASSERT(wpipe->pipe_buffer.cnt <=
1161                                         wpipe->pipe_buffer.size,
1162                                         ("Pipe buffer overflow"));
1163                         }
1164                         pipeunlock(wpipe);
1165                         if (error != 0)
1166                                 break;
1167                 } else {
1168                         /*
1169                          * If the "read-side" has been blocked, wake it up now.
1170                          */
1171                         if (wpipe->pipe_state & PIPE_WANTR) {
1172                                 wpipe->pipe_state &= ~PIPE_WANTR;
1173                                 wakeup(wpipe);
1174                         }
1175
1176                         /*
1177                          * don't block on non-blocking I/O
1178                          */
1179                         if (fp->f_flag & FNONBLOCK) {
1180                                 error = EAGAIN;
1181                                 pipeunlock(wpipe);
1182                                 break;
1183                         }
1184
1185                         /*
1186                          * We have no more space and have something to offer,
1187                          * wake up select/poll.
1188                          */
1189                         pipeselwakeup(wpipe);
1190
1191                         wpipe->pipe_state |= PIPE_WANTW;
1192                         pipeunlock(wpipe);
1193                         error = msleep(wpipe, PIPE_MTX(rpipe),
1194                             PRIBIO | PCATCH, "pipewr", 0);
1195                         if (error != 0)
1196                                 break;
1197                 }
1198         }
1199
1200         pipelock(wpipe, 0);
1201         --wpipe->pipe_busy;
1202
1203         if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1204                 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1205                 wakeup(wpipe);
1206         } else if (wpipe->pipe_buffer.cnt > 0) {
1207                 /*
1208                  * If we have put any characters in the buffer, we wake up
1209                  * the reader.
1210                  */
1211                 if (wpipe->pipe_state & PIPE_WANTR) {
1212                         wpipe->pipe_state &= ~PIPE_WANTR;
1213                         wakeup(wpipe);
1214                 }
1215         }
1216
1217         /*
1218          * Don't return EPIPE if I/O was successful
1219          */
1220         if ((wpipe->pipe_buffer.cnt == 0) &&
1221             (uio->uio_resid == 0) &&
1222             (error == EPIPE)) {
1223                 error = 0;
1224         }
1225
1226         if (error == 0)
1227                 vfs_timestamp(&wpipe->pipe_mtime);
1228
1229         /*
1230          * We have something to offer,
1231          * wake up select/poll.
1232          */
1233         if (wpipe->pipe_buffer.cnt)
1234                 pipeselwakeup(wpipe);
1235
1236         pipeunlock(wpipe);
1237         PIPE_UNLOCK(rpipe);
1238         return (error);
1239 }
1240
1241 /* ARGSUSED */
1242 static int
1243 pipe_truncate(fp, length, active_cred, td)
1244         struct file *fp;
1245         off_t length;
1246         struct ucred *active_cred;
1247         struct thread *td;
1248 {
1249
1250         return (EINVAL);
1251 }
1252
1253 /*
1254  * we implement a very minimal set of ioctls for compatibility with sockets.
1255  */
1256 static int
1257 pipe_ioctl(fp, cmd, data, active_cred, td)
1258         struct file *fp;
1259         u_long cmd;
1260         void *data;
1261         struct ucred *active_cred;
1262         struct thread *td;
1263 {
1264         struct pipe *mpipe = fp->f_data;
1265         int error;
1266
1267         PIPE_LOCK(mpipe);
1268
1269 #ifdef MAC
1270         error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data);
1271         if (error) {
1272                 PIPE_UNLOCK(mpipe);
1273                 return (error);
1274         }
1275 #endif
1276
1277         error = 0;
1278         switch (cmd) {
1279
1280         case FIONBIO:
1281                 break;
1282
1283         case FIOASYNC:
1284                 if (*(int *)data) {
1285                         mpipe->pipe_state |= PIPE_ASYNC;
1286                 } else {
1287                         mpipe->pipe_state &= ~PIPE_ASYNC;
1288                 }
1289                 break;
1290
1291         case FIONREAD:
1292                 if (mpipe->pipe_state & PIPE_DIRECTW)
1293                         *(int *)data = mpipe->pipe_map.cnt;
1294                 else
1295                         *(int *)data = mpipe->pipe_buffer.cnt;
1296                 break;
1297
1298         case FIOSETOWN:
1299                 PIPE_UNLOCK(mpipe);
1300                 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
1301                 goto out_unlocked;
1302
1303         case FIOGETOWN:
1304                 *(int *)data = fgetown(&mpipe->pipe_sigio);
1305                 break;
1306
1307         /* This is deprecated, FIOSETOWN should be used instead. */
1308         case TIOCSPGRP:
1309                 PIPE_UNLOCK(mpipe);
1310                 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
1311                 goto out_unlocked;
1312
1313         /* This is deprecated, FIOGETOWN should be used instead. */
1314         case TIOCGPGRP:
1315                 *(int *)data = -fgetown(&mpipe->pipe_sigio);
1316                 break;
1317
1318         default:
1319                 error = ENOTTY;
1320                 break;
1321         }
1322         PIPE_UNLOCK(mpipe);
1323 out_unlocked:
1324         return (error);
1325 }
1326
1327 static int
1328 pipe_poll(fp, events, active_cred, td)
1329         struct file *fp;
1330         int events;
1331         struct ucred *active_cred;
1332         struct thread *td;
1333 {
1334         struct pipe *rpipe = fp->f_data;
1335         struct pipe *wpipe;
1336         int revents = 0;
1337 #ifdef MAC
1338         int error;
1339 #endif
1340
1341         wpipe = rpipe->pipe_peer;
1342         PIPE_LOCK(rpipe);
1343 #ifdef MAC
1344         error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair);
1345         if (error)
1346                 goto locked_error;
1347 #endif
1348         if (events & (POLLIN | POLLRDNORM))
1349                 if ((rpipe->pipe_state & PIPE_DIRECTW) ||
1350                     (rpipe->pipe_buffer.cnt > 0))
1351                         revents |= events & (POLLIN | POLLRDNORM);
1352
1353         if (events & (POLLOUT | POLLWRNORM))
1354                 if (wpipe->pipe_present != PIPE_ACTIVE ||
1355                     (wpipe->pipe_state & PIPE_EOF) ||
1356                     (((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
1357                      (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
1358                         revents |= events & (POLLOUT | POLLWRNORM);
1359
1360         if ((events & POLLINIGNEOF) == 0) {
1361                 if (rpipe->pipe_state & PIPE_EOF) {
1362                         revents |= (events & (POLLIN | POLLRDNORM));
1363                         if (wpipe->pipe_present != PIPE_ACTIVE ||
1364                             (wpipe->pipe_state & PIPE_EOF))
1365                                 revents |= POLLHUP;
1366                 }
1367         }
1368
1369         if (revents == 0) {
1370                 if (events & (POLLIN | POLLRDNORM)) {
1371                         selrecord(td, &rpipe->pipe_sel);
1372                         if (SEL_WAITING(&rpipe->pipe_sel))
1373                                 rpipe->pipe_state |= PIPE_SEL;
1374                 }
1375
1376                 if (events & (POLLOUT | POLLWRNORM)) {
1377                         selrecord(td, &wpipe->pipe_sel);
1378                         if (SEL_WAITING(&wpipe->pipe_sel))
1379                                 wpipe->pipe_state |= PIPE_SEL;
1380                 }
1381         }
1382 #ifdef MAC
1383 locked_error:
1384 #endif
1385         PIPE_UNLOCK(rpipe);
1386
1387         return (revents);
1388 }
1389
1390 /*
1391  * We shouldn't need locks here as we're doing a read and this should
1392  * be a natural race.
1393  */
1394 static int
1395 pipe_stat(fp, ub, active_cred, td)
1396         struct file *fp;
1397         struct stat *ub;
1398         struct ucred *active_cred;
1399         struct thread *td;
1400 {
1401         struct pipe *pipe = fp->f_data;
1402 #ifdef MAC
1403         int error;
1404
1405         PIPE_LOCK(pipe);
1406         error = mac_pipe_check_stat(active_cred, pipe->pipe_pair);
1407         PIPE_UNLOCK(pipe);
1408         if (error)
1409                 return (error);
1410 #endif
1411         bzero(ub, sizeof(*ub));
1412         ub->st_mode = S_IFIFO;
1413         ub->st_blksize = PAGE_SIZE;
1414         if (pipe->pipe_state & PIPE_DIRECTW)
1415                 ub->st_size = pipe->pipe_map.cnt;
1416         else
1417                 ub->st_size = pipe->pipe_buffer.cnt;
1418         ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
1419         ub->st_atim = pipe->pipe_atime;
1420         ub->st_mtim = pipe->pipe_mtime;
1421         ub->st_ctim = pipe->pipe_ctime;
1422         ub->st_uid = fp->f_cred->cr_uid;
1423         ub->st_gid = fp->f_cred->cr_gid;
1424         ub->st_dev = pipedev_ino;
1425         ub->st_ino = pipe->pipe_ino;
1426         /*
1427          * Left as 0: st_nlink, st_rdev, st_flags, st_gen.
1428          */
1429         return (0);
1430 }
1431
1432 /* ARGSUSED */
1433 static int
1434 pipe_close(fp, td)
1435         struct file *fp;
1436         struct thread *td;
1437 {
1438         struct pipe *cpipe = fp->f_data;
1439
1440         fp->f_ops = &badfileops;
1441         fp->f_data = NULL;
1442         funsetown(&cpipe->pipe_sigio);
1443         pipeclose(cpipe);
1444         return (0);
1445 }
1446
1447 static void
1448 pipe_free_kmem(cpipe)
1449         struct pipe *cpipe;
1450 {
1451
1452         KASSERT(!mtx_owned(PIPE_MTX(cpipe)),
1453             ("pipe_free_kmem: pipe mutex locked"));
1454
1455         if (cpipe->pipe_buffer.buffer != NULL) {
1456                 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size);
1457                 vm_map_remove(pipe_map,
1458                     (vm_offset_t)cpipe->pipe_buffer.buffer,
1459                     (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size);
1460                 cpipe->pipe_buffer.buffer = NULL;
1461         }
1462 #ifndef PIPE_NODIRECT
1463         {
1464                 cpipe->pipe_map.cnt = 0;
1465                 cpipe->pipe_map.pos = 0;
1466                 cpipe->pipe_map.npages = 0;
1467         }
1468 #endif
1469 }
1470
1471 /*
1472  * shutdown the pipe
1473  */
1474 static void
1475 pipeclose(cpipe)
1476         struct pipe *cpipe;
1477 {
1478         struct pipepair *pp;
1479         struct pipe *ppipe;
1480         ino_t ino;
1481
1482         KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL"));
1483
1484         PIPE_LOCK(cpipe);
1485         pipelock(cpipe, 0);
1486         pp = cpipe->pipe_pair;
1487
1488         pipeselwakeup(cpipe);
1489
1490         /*
1491          * If the other side is blocked, wake it up saying that
1492          * we want to close it down.
1493          */
1494         cpipe->pipe_state |= PIPE_EOF;
1495         while (cpipe->pipe_busy) {
1496                 wakeup(cpipe);
1497                 cpipe->pipe_state |= PIPE_WANT;
1498                 pipeunlock(cpipe);
1499                 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
1500                 pipelock(cpipe, 0);
1501         }
1502
1503
1504         /*
1505          * Disconnect from peer, if any.
1506          */
1507         ppipe = cpipe->pipe_peer;
1508         if (ppipe->pipe_present == PIPE_ACTIVE) {
1509                 pipeselwakeup(ppipe);
1510
1511                 ppipe->pipe_state |= PIPE_EOF;
1512                 wakeup(ppipe);
1513                 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0);
1514         }
1515
1516         /*
1517          * Mark this endpoint as free.  Release kmem resources.  We
1518          * don't mark this endpoint as unused until we've finished
1519          * doing that, or the pipe might disappear out from under
1520          * us.
1521          */
1522         PIPE_UNLOCK(cpipe);
1523         pipe_free_kmem(cpipe);
1524         PIPE_LOCK(cpipe);
1525         cpipe->pipe_present = PIPE_CLOSING;
1526         pipeunlock(cpipe);
1527
1528         /*
1529          * knlist_clear() may sleep dropping the PIPE_MTX. Set the
1530          * PIPE_FINALIZED, that allows other end to free the
1531          * pipe_pair, only after the knotes are completely dismantled.
1532          */
1533         knlist_clear(&cpipe->pipe_sel.si_note, 1);
1534         cpipe->pipe_present = PIPE_FINALIZED;
1535         seldrain(&cpipe->pipe_sel);
1536         knlist_destroy(&cpipe->pipe_sel.si_note);
1537
1538         /*
1539          * Postpone the destroy of the fake inode number allocated for
1540          * our end, until pipe mtx is unlocked.
1541          */
1542         ino = cpipe->pipe_ino;
1543
1544         /*
1545          * If both endpoints are now closed, release the memory for the
1546          * pipe pair.  If not, unlock.
1547          */
1548         if (ppipe->pipe_present == PIPE_FINALIZED) {
1549                 PIPE_UNLOCK(cpipe);
1550 #ifdef MAC
1551                 mac_pipe_destroy(pp);
1552 #endif
1553                 uma_zfree(pipe_zone, cpipe->pipe_pair);
1554         } else
1555                 PIPE_UNLOCK(cpipe);
1556
1557         if (ino > 0)
1558                 free_unr(pipeino_unr, cpipe->pipe_ino);
1559 }
1560
1561 /*ARGSUSED*/
1562 static int
1563 pipe_kqfilter(struct file *fp, struct knote *kn)
1564 {
1565         struct pipe *cpipe;
1566
1567         cpipe = kn->kn_fp->f_data;
1568         PIPE_LOCK(cpipe);
1569         switch (kn->kn_filter) {
1570         case EVFILT_READ:
1571                 kn->kn_fop = &pipe_rfiltops;
1572                 break;
1573         case EVFILT_WRITE:
1574                 kn->kn_fop = &pipe_wfiltops;
1575                 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) {
1576                         /* other end of pipe has been closed */
1577                         PIPE_UNLOCK(cpipe);
1578                         return (EPIPE);
1579                 }
1580                 cpipe = cpipe->pipe_peer;
1581                 break;
1582         default:
1583                 PIPE_UNLOCK(cpipe);
1584                 return (EINVAL);
1585         }
1586
1587         knlist_add(&cpipe->pipe_sel.si_note, kn, 1);
1588         PIPE_UNLOCK(cpipe);
1589         return (0);
1590 }
1591
1592 static void
1593 filt_pipedetach(struct knote *kn)
1594 {
1595         struct pipe *cpipe = (struct pipe *)kn->kn_fp->f_data;
1596
1597         PIPE_LOCK(cpipe);
1598         if (kn->kn_filter == EVFILT_WRITE)
1599                 cpipe = cpipe->pipe_peer;
1600         knlist_remove(&cpipe->pipe_sel.si_note, kn, 1);
1601         PIPE_UNLOCK(cpipe);
1602 }
1603
1604 /*ARGSUSED*/
1605 static int
1606 filt_piperead(struct knote *kn, long hint)
1607 {
1608         struct pipe *rpipe = kn->kn_fp->f_data;
1609         struct pipe *wpipe = rpipe->pipe_peer;
1610         int ret;
1611
1612         PIPE_LOCK(rpipe);
1613         kn->kn_data = rpipe->pipe_buffer.cnt;
1614         if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
1615                 kn->kn_data = rpipe->pipe_map.cnt;
1616
1617         if ((rpipe->pipe_state & PIPE_EOF) ||
1618             wpipe->pipe_present != PIPE_ACTIVE ||
1619             (wpipe->pipe_state & PIPE_EOF)) {
1620                 kn->kn_flags |= EV_EOF;
1621                 PIPE_UNLOCK(rpipe);
1622                 return (1);
1623         }
1624         ret = kn->kn_data > 0;
1625         PIPE_UNLOCK(rpipe);
1626         return ret;
1627 }
1628
1629 /*ARGSUSED*/
1630 static int
1631 filt_pipewrite(struct knote *kn, long hint)
1632 {
1633         struct pipe *rpipe = kn->kn_fp->f_data;
1634         struct pipe *wpipe = rpipe->pipe_peer;
1635
1636         PIPE_LOCK(rpipe);
1637         if (wpipe->pipe_present != PIPE_ACTIVE ||
1638             (wpipe->pipe_state & PIPE_EOF)) {
1639                 kn->kn_data = 0;
1640                 kn->kn_flags |= EV_EOF;
1641                 PIPE_UNLOCK(rpipe);
1642                 return (1);
1643         }
1644         kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1645         if (wpipe->pipe_state & PIPE_DIRECTW)
1646                 kn->kn_data = 0;
1647
1648         PIPE_UNLOCK(rpipe);
1649         return (kn->kn_data >= PIPE_BUF);
1650 }