sys/kern/sys_pipe.c

   1 /*-
   2  * Copyright (c) 1996 John S. Dyson
   3  * Copyright (c) 2012 Giovanni Trematerra
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice immediately at the beginning of the file, without modification,
  11  *    this list of conditions, and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Absolutely no warranty of function or purpose is made by the author
  16  *    John S. Dyson.
  17  * 4. Modifications may be freely made to this file if the above conditions
  18  *    are met.
  19  */
  20
  21 /*
  22  * This file contains a high-performance replacement for the socket-based
  23  * pipes scheme originally used in FreeBSD/4.4Lite.  It does not support
  24  * all features of sockets, but does do everything that pipes normally
  25  * do.
  26  */
  27
  28 /*
  29  * This code has two modes of operation, a small write mode and a large
  30  * write mode.  The small write mode acts like conventional pipes with
  31  * a kernel buffer.  If the buffer is less than PIPE_MINDIRECT, then the
  32  * "normal" pipe buffering is done.  If the buffer is between PIPE_MINDIRECT
  33  * and PIPE_SIZE in size, the sending process pins the underlying pages in
  34  * memory, and the receiving process copies directly from these pinned pages
  35  * in the sending process.
  36  *
  37  * If the sending process receives a signal, it is possible that it will
  38  * go away, and certainly its address space can change, because control
  39  * is returned back to the user-mode side.  In that case, the pipe code
  40  * arranges to copy the buffer supplied by the user process, to a pageable
  41  * kernel buffer, and the receiving process will grab the data from the
  42  * pageable kernel buffer.  Since signals don't happen all that often,
  43  * the copy operation is normally eliminated.
  44  *
  45  * The constant PIPE_MINDIRECT is chosen to make sure that buffering will
  46  * happen for small transfers so that the system will not spend all of
  47  * its time context switching.
  48  *
  49  * In order to limit the resource use of pipes, two sysctls exist:
  50  *
  51  * kern.ipc.maxpipekva - This is a hard limit on the amount of pageable
  52  * address space available to us in pipe_map. This value is normally
  53  * autotuned, but may also be loader tuned.
  54  *
  55  * kern.ipc.pipekva - This read-only sysctl tracks the current amount of
  56  * memory in use by pipes.
  57  *
  58  * Based on how large pipekva is relative to maxpipekva, the following
  59  * will happen:
  60  *
  61  * 0% - 50%:
  62  *     New pipes are given 16K of memory backing, pipes may dynamically
  63  *     grow to as large as 64K where needed.
  64  * 50% - 75%:
  65  *     New pipes are given 4K (or PAGE_SIZE) of memory backing,
  66  *     existing pipes may NOT grow.
  67  * 75% - 100%:
  68  *     New pipes are given 4K (or PAGE_SIZE) of memory backing,
  69  *     existing pipes will be shrunk down to 4K whenever possible.
  70  *
  71  * Resizing may be disabled by setting kern.ipc.piperesizeallowed=0.  If
  72  * that is set,  the only resize that will occur is the 0 -> SMALL_PIPE_SIZE
  73  * resize which MUST occur for reverse-direction pipes when they are
  74  * first used.
  75  *
  76  * Additional information about the current state of pipes may be obtained
  77  * from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail,
  78  * and kern.ipc.piperesizefail.
  79  *
  80  * Locking rules:  There are two locks present here:  A mutex, used via
  81  * PIPE_LOCK, and a flag, used via pipelock().  All locking is done via
  82  * the flag, as mutexes can not persist over uiomove.  The mutex
  83  * exists only to guard access to the flag, and is not in itself a
  84  * locking mechanism.  Also note that there is only a single mutex for
  85  * both directions of a pipe.
  86  *
  87  * As pipelock() may have to sleep before it can acquire the flag, it
  88  * is important to reread all data after a call to pipelock(); everything
  89  * in the structure may have changed.
  90  */
  91
  92 #include <sys/cdefs.h>
  93 __FBSDID("$FreeBSD$");
  94
  95 #include <sys/param.h>
  96 #include <sys/systm.h>
  97 #include <sys/conf.h>
  98 #include <sys/fcntl.h>
  99 #include <sys/file.h>
 100 #include <sys/filedesc.h>
 101 #include <sys/filio.h>
 102 #include <sys/kernel.h>
 103 #include <sys/lock.h>
 104 #include <sys/mutex.h>
 105 #include <sys/ttycom.h>
 106 #include <sys/stat.h>
 107 #include <sys/malloc.h>
 108 #include <sys/poll.h>
 109 #include <sys/selinfo.h>
 110 #include <sys/signalvar.h>
 111 #include <sys/syscallsubr.h>
 112 #include <sys/sysctl.h>
 113 #include <sys/sysproto.h>
 114 #include <sys/pipe.h>
 115 #include <sys/proc.h>
 116 #include <sys/vnode.h>
 117 #include <sys/uio.h>
 118 #include <sys/event.h>
 119
 120 #include <security/mac/mac_framework.h>
 121
 122 #include <vm/vm.h>
 123 #include <vm/vm_param.h>
 124 #include <vm/vm_object.h>
 125 #include <vm/vm_kern.h>
 126 #include <vm/vm_extern.h>
 127 #include <vm/pmap.h>
 128 #include <vm/vm_map.h>
 129 #include <vm/vm_page.h>
 130 #include <vm/uma.h>
 131
 132 /*
 133  * Use this define if you want to disable *fancy* VM things.  Expect an
 134  * approx 30% decrease in transfer rate.  This could be useful for
 135  * NetBSD or OpenBSD.
 136  */
 137 /* #define PIPE_NODIRECT */
 138
 139 #define PIPE_PEER(pipe) \
 140         (((pipe)->pipe_state & PIPE_NAMED) ? (pipe) : ((pipe)->pipe_peer))
 141
 142 /*
 143  * interfaces to the outside world
 144  */
 145 static fo_rdwr_t        pipe_read;
 146 static fo_rdwr_t        pipe_write;
 147 static fo_truncate_t    pipe_truncate;
 148 static fo_ioctl_t       pipe_ioctl;
 149 static fo_poll_t        pipe_poll;
 150 static fo_kqfilter_t    pipe_kqfilter;
 151 static fo_stat_t        pipe_stat;
 152 static fo_close_t       pipe_close;
 153 static fo_chmod_t       pipe_chmod;
 154 static fo_chown_t       pipe_chown;
 155
 156 struct fileops pipeops = {
 157         .fo_read = pipe_read,
 158         .fo_write = pipe_write,
 159         .fo_truncate = pipe_truncate,
 160         .fo_ioctl = pipe_ioctl,
 161         .fo_poll = pipe_poll,
 162         .fo_kqfilter = pipe_kqfilter,
 163         .fo_stat = pipe_stat,
 164         .fo_close = pipe_close,
 165         .fo_chmod = pipe_chmod,
 166         .fo_chown = pipe_chown,
 167         .fo_flags = DFLAG_PASSABLE
 168 };
 169
 170 static void     filt_pipedetach(struct knote *kn);
 171 static void     filt_pipedetach_notsup(struct knote *kn);
 172 static int      filt_pipenotsup(struct knote *kn, long hint);
 173 static int      filt_piperead(struct knote *kn, long hint);
 174 static int      filt_pipewrite(struct knote *kn, long hint);
 175
 176 static struct filterops pipe_nfiltops = {
 177         .f_isfd = 1,
 178         .f_detach = filt_pipedetach_notsup,
 179         .f_event = filt_pipenotsup
 180 };
 181 static struct filterops pipe_rfiltops = {
 182         .f_isfd = 1,
 183         .f_detach = filt_pipedetach,
 184         .f_event = filt_piperead
 185 };
 186 static struct filterops pipe_wfiltops = {
 187         .f_isfd = 1,
 188         .f_detach = filt_pipedetach,
 189         .f_event = filt_pipewrite
 190 };
 191
 192 /*
 193  * Default pipe buffer size(s), this can be kind-of large now because pipe
 194  * space is pageable.  The pipe code will try to maintain locality of
 195  * reference for performance reasons, so small amounts of outstanding I/O
 196  * will not wipe the cache.
 197  */
 198 #define MINPIPESIZE (PIPE_SIZE/3)
 199 #define MAXPIPESIZE (2*PIPE_SIZE/3)
 200
 201 static long amountpipekva;
 202 static int pipefragretry;
 203 static int pipeallocfail;
 204 static int piperesizefail;
 205 static int piperesizeallowed = 1;
 206
 207 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN,
 208            &maxpipekva, 0, "Pipe KVA limit");
 209 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD,
 210            &amountpipekva, 0, "Pipe KVA usage");
 211 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD,
 212           &pipefragretry, 0, "Pipe allocation retries due to fragmentation");
 213 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD,
 214           &pipeallocfail, 0, "Pipe allocation failures");
 215 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD,
 216           &piperesizefail, 0, "Pipe resize failures");
 217 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW,
 218           &piperesizeallowed, 0, "Pipe resizing allowed");
 219
 220 static void pipeinit(void *dummy __unused);
 221 static void pipeclose(struct pipe *cpipe);
 222 static void pipe_free_kmem(struct pipe *cpipe);
 223 static int pipe_create(struct pipe *pipe, int backing);
 224 static int pipe_paircreate(struct thread *td, struct pipepair **p_pp);
 225 static __inline int pipelock(struct pipe *cpipe, int catch);
 226 static __inline void pipeunlock(struct pipe *cpipe);
 227 #ifndef PIPE_NODIRECT
 228 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio);
 229 static void pipe_destroy_write_buffer(struct pipe *wpipe);
 230 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio);
 231 static void pipe_clone_write_buffer(struct pipe *wpipe);
 232 #endif
 233 static int pipespace(struct pipe *cpipe, int size);
 234 static int pipespace_new(struct pipe *cpipe, int size);
 235
 236 static int      pipe_zone_ctor(void *mem, int size, void *arg, int flags);
 237 static int      pipe_zone_init(void *mem, int size, int flags);
 238 static void     pipe_zone_fini(void *mem, int size);
 239
 240 static uma_zone_t pipe_zone;
 241 static struct unrhdr *pipeino_unr;
 242 static dev_t pipedev_ino;
 243
 244 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
 245
 246 static void
 247 pipeinit(void *dummy __unused)
 248 {
 249
 250         pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair),
 251             pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini,
 252             UMA_ALIGN_PTR, 0);
 253         KASSERT(pipe_zone != NULL, ("pipe_zone not initialized"));
 254         pipeino_unr = new_unrhdr(1, INT32_MAX, NULL);
 255         KASSERT(pipeino_unr != NULL, ("pipe fake inodes not initialized"));
 256         pipedev_ino = devfs_alloc_cdp_inode();
 257         KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized"));
 258 }
 259
 260 static int
 261 pipe_zone_ctor(void *mem, int size, void *arg, int flags)
 262 {
 263         struct pipepair *pp;
 264         struct pipe *rpipe, *wpipe;
 265
 266         KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size"));
 267
 268         pp = (struct pipepair *)mem;
 269
 270         /*
 271          * We zero both pipe endpoints to make sure all the kmem pointers
 272          * are NULL, flag fields are zero'd, etc.  We timestamp both
 273          * endpoints with the same time.
 274          */
 275         rpipe = &pp->pp_rpipe;
 276         bzero(rpipe, sizeof(*rpipe));
 277         vfs_timestamp(&rpipe->pipe_ctime);
 278         rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime;
 279
 280         wpipe = &pp->pp_wpipe;
 281         bzero(wpipe, sizeof(*wpipe));
 282         wpipe->pipe_ctime = rpipe->pipe_ctime;
 283         wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime;
 284
 285         rpipe->pipe_peer = wpipe;
 286         rpipe->pipe_pair = pp;
 287         wpipe->pipe_peer = rpipe;
 288         wpipe->pipe_pair = pp;
 289
 290         /*
 291          * Mark both endpoints as present; they will later get free'd
 292          * one at a time.  When both are free'd, then the whole pair
 293          * is released.
 294          */
 295         rpipe->pipe_present = PIPE_ACTIVE;
 296         wpipe->pipe_present = PIPE_ACTIVE;
 297
 298         /*
 299          * Eventually, the MAC Framework may initialize the label
 300          * in ctor or init, but for now we do it elswhere to avoid
 301          * blocking in ctor or init.
 302          */
 303         pp->pp_label = NULL;
 304
 305         return (0);
 306 }
 307
 308 static int
 309 pipe_zone_init(void *mem, int size, int flags)
 310 {
 311         struct pipepair *pp;
 312
 313         KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size"));
 314
 315         pp = (struct pipepair *)mem;
 316
 317         mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_RECURSE);
 318         return (0);
 319 }
 320
 321 static void
 322 pipe_zone_fini(void *mem, int size)
 323 {
 324         struct pipepair *pp;
 325
 326         KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size"));
 327
 328         pp = (struct pipepair *)mem;
 329
 330         mtx_destroy(&pp->pp_mtx);
 331 }
 332
 333 static int
 334 pipe_paircreate(struct thread *td, struct pipepair **p_pp)
 335 {
 336         struct pipepair *pp;
 337         struct pipe *rpipe, *wpipe;
 338         int error;
 339
 340         *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK);
 341 #ifdef MAC
 342         /*
 343          * The MAC label is shared between the connected endpoints.  As a
 344          * result mac_pipe_init() and mac_pipe_create() are called once
 345          * for the pair, and not on the endpoints.
 346          */
 347         mac_pipe_init(pp);
 348         mac_pipe_create(td->td_ucred, pp);
 349 #endif
 350         rpipe = &pp->pp_rpipe;
 351         wpipe = &pp->pp_wpipe;
 352
 353         knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe));
 354         knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe));
 355
 356         /* Only the forward direction pipe is backed by default */
 357         if ((error = pipe_create(rpipe, 1)) != 0 ||
 358             (error = pipe_create(wpipe, 0)) != 0) {
 359                 pipeclose(rpipe);
 360                 pipeclose(wpipe);
 361                 return (error);
 362         }
 363
 364         rpipe->pipe_state |= PIPE_DIRECTOK;
 365         wpipe->pipe_state |= PIPE_DIRECTOK;
 366         return (0);
 367 }
 368
 369 int
 370 pipe_named_ctor(struct pipe **ppipe, struct thread *td)
 371 {
 372         struct pipepair *pp;
 373         int error;
 374
 375         error = pipe_paircreate(td, &pp);
 376         if (error != 0)
 377                 return (error);
 378         pp->pp_rpipe.pipe_state |= PIPE_NAMED;
 379         *ppipe = &pp->pp_rpipe;
 380         return (0);
 381 }
 382
 383 void
 384 pipe_dtor(struct pipe *dpipe)
 385 {
 386         ino_t ino;
 387
 388         ino = dpipe->pipe_ino;
 389         funsetown(&dpipe->pipe_sigio);
 390         pipeclose(dpipe);
 391         if (dpipe->pipe_state & PIPE_NAMED) {
 392                 dpipe = dpipe->pipe_peer;
 393                 funsetown(&dpipe->pipe_sigio);
 394                 pipeclose(dpipe);
 395         }
 396         if (ino != 0 && ino != (ino_t)-1)
 397                 free_unr(pipeino_unr, ino);
 398 }
 399
 400 /*
 401  * The pipe system call for the DTYPE_PIPE type of pipes.  If we fail, let
 402  * the zone pick up the pieces via pipeclose().
 403  */
 404 int
 405 kern_pipe(struct thread *td, int fildes[2])
 406 {
 407
 408         return (kern_pipe2(td, fildes, 0));
 409 }
 410
 411 int
 412 kern_pipe2(struct thread *td, int fildes[2], int flags)
 413 {
 414         struct filedesc *fdp;
 415         struct file *rf, *wf;
 416         struct pipe *rpipe, *wpipe;
 417         struct pipepair *pp;
 418         int fd, fflags, error;
 419
 420         fdp = td->td_proc->p_fd;
 421         error = pipe_paircreate(td, &pp);
 422         if (error != 0)
 423                 return (error);
 424         rpipe = &pp->pp_rpipe;
 425         wpipe = &pp->pp_wpipe;
 426         error = falloc(td, &rf, &fd, flags);
 427         if (error) {
 428                 pipeclose(rpipe);
 429                 pipeclose(wpipe);
 430                 return (error);
 431         }
 432         /* An extra reference on `rf' has been held for us by falloc(). */
 433         fildes[0] = fd;
 434
 435         fflags = FREAD | FWRITE;
 436         if ((flags & O_NONBLOCK) != 0)
 437                 fflags |= FNONBLOCK;
 438
 439         /*
 440          * Warning: once we've gotten past allocation of the fd for the
 441          * read-side, we can only drop the read side via fdrop() in order
 442          * to avoid races against processes which manage to dup() the read
 443          * side while we are blocked trying to allocate the write side.
 444          */
 445         finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops);
 446         error = falloc(td, &wf, &fd, flags);
 447         if (error) {
 448                 fdclose(fdp, rf, fildes[0], td);
 449                 fdrop(rf, td);
 450                 /* rpipe has been closed by fdrop(). */
 451                 pipeclose(wpipe);
 452                 return (error);
 453         }
 454         /* An extra reference on `wf' has been held for us by falloc(). */
 455         finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops);
 456         fdrop(wf, td);
 457         fildes[1] = fd;
 458         fdrop(rf, td);
 459
 460         return (0);
 461 }
 462
 463 /* ARGSUSED */
 464 int
 465 sys_pipe(struct thread *td, struct pipe_args *uap)
 466 {
 467         int error;
 468         int fildes[2];
 469
 470         error = kern_pipe(td, fildes);
 471         if (error)
 472                 return (error);
 473
 474         td->td_retval[0] = fildes[0];
 475         td->td_retval[1] = fildes[1];
 476
 477         return (0);
 478 }
 479
 480 /*
 481  * Allocate kva for pipe circular buffer, the space is pageable
 482  * This routine will 'realloc' the size of a pipe safely, if it fails
 483  * it will retain the old buffer.
 484  * If it fails it will return ENOMEM.
 485  */
 486 static int
 487 pipespace_new(cpipe, size)
 488         struct pipe *cpipe;
 489         int size;
 490 {
 491         caddr_t buffer;
 492         int error, cnt, firstseg;
 493         static int curfail = 0;
 494         static struct timeval lastfail;
 495
 496         KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked"));
 497         KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW),
 498                 ("pipespace: resize of direct writes not allowed"));
 499 retry:
 500         cnt = cpipe->pipe_buffer.cnt;
 501         if (cnt > size)
 502                 size = cnt;
 503
 504         size = round_page(size);
 505         buffer = (caddr_t) vm_map_min(pipe_map);
 506
 507         error = vm_map_find(pipe_map, NULL, 0,
 508                 (vm_offset_t *) &buffer, size, 1,
 509                 VM_PROT_ALL, VM_PROT_ALL, 0);
 510         if (error != KERN_SUCCESS) {
 511                 if ((cpipe->pipe_buffer.buffer == NULL) &&
 512                         (size > SMALL_PIPE_SIZE)) {
 513                         size = SMALL_PIPE_SIZE;
 514                         pipefragretry++;
 515                         goto retry;
 516                 }
 517                 if (cpipe->pipe_buffer.buffer == NULL) {
 518                         pipeallocfail++;
 519                         if (ppsratecheck(&lastfail, &curfail, 1))
 520                                 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n");
 521                 } else {
 522                         piperesizefail++;
 523                 }
 524                 return (ENOMEM);
 525         }
 526
 527         /* copy data, then free old resources if we're resizing */
 528         if (cnt > 0) {
 529                 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) {
 530                         firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out;
 531                         bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
 532                                 buffer, firstseg);
 533                         if ((cnt - firstseg) > 0)
 534                                 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg],
 535                                         cpipe->pipe_buffer.in);
 536                 } else {
 537                         bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
 538                                 buffer, cnt);
 539                 }
 540         }
 541         pipe_free_kmem(cpipe);
 542         cpipe->pipe_buffer.buffer = buffer;
 543         cpipe->pipe_buffer.size = size;
 544         cpipe->pipe_buffer.in = cnt;
 545         cpipe->pipe_buffer.out = 0;
 546         cpipe->pipe_buffer.cnt = cnt;
 547         atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size);
 548         return (0);
 549 }
 550
 551 /*
 552  * Wrapper for pipespace_new() that performs locking assertions.
 553  */
 554 static int
 555 pipespace(cpipe, size)
 556         struct pipe *cpipe;
 557         int size;
 558 {
 559
 560         KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
 561                 ("Unlocked pipe passed to pipespace"));
 562         return (pipespace_new(cpipe, size));
 563 }
 564
 565 /*
 566  * lock a pipe for I/O, blocking other access
 567  */
 568 static __inline int
 569 pipelock(cpipe, catch)
 570         struct pipe *cpipe;
 571         int catch;
 572 {
 573         int error;
 574
 575         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 576         while (cpipe->pipe_state & PIPE_LOCKFL) {
 577                 cpipe->pipe_state |= PIPE_LWANT;
 578                 error = msleep(cpipe, PIPE_MTX(cpipe),
 579                     catch ? (PRIBIO | PCATCH) : PRIBIO,
 580                     "pipelk", 0);
 581                 if (error != 0)
 582                         return (error);
 583         }
 584         cpipe->pipe_state |= PIPE_LOCKFL;
 585         return (0);
 586 }
 587
 588 /*
 589  * unlock a pipe I/O lock
 590  */
 591 static __inline void
 592 pipeunlock(cpipe)
 593         struct pipe *cpipe;
 594 {
 595
 596         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 597         KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
 598                 ("Unlocked pipe passed to pipeunlock"));
 599         cpipe->pipe_state &= ~PIPE_LOCKFL;
 600         if (cpipe->pipe_state & PIPE_LWANT) {
 601                 cpipe->pipe_state &= ~PIPE_LWANT;
 602                 wakeup(cpipe);
 603         }
 604 }
 605
 606 void
 607 pipeselwakeup(cpipe)
 608         struct pipe *cpipe;
 609 {
 610
 611         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 612         if (cpipe->pipe_state & PIPE_SEL) {
 613                 selwakeuppri(&cpipe->pipe_sel, PSOCK);
 614                 if (!SEL_WAITING(&cpipe->pipe_sel))
 615                         cpipe->pipe_state &= ~PIPE_SEL;
 616         }
 617         if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
 618                 pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
 619         KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0);
 620 }
 621
 622 /*
 623  * Initialize and allocate VM and memory for pipe.  The structure
 624  * will start out zero'd from the ctor, so we just manage the kmem.
 625  */
 626 static int
 627 pipe_create(pipe, backing)
 628         struct pipe *pipe;
 629         int backing;
 630 {
 631         int error;
 632
 633         if (backing) {
 634                 if (amountpipekva > maxpipekva / 2)
 635                         error = pipespace_new(pipe, SMALL_PIPE_SIZE);
 636                 else
 637                         error = pipespace_new(pipe, PIPE_SIZE);
 638         } else {
 639                 /* If we're not backing this pipe, no need to do anything. */
 640                 error = 0;
 641         }
 642         pipe->pipe_ino = -1;
 643         return (error);
 644 }
 645
 646 /* ARGSUSED */
 647 static int
 648 pipe_read(fp, uio, active_cred, flags, td)
 649         struct file *fp;
 650         struct uio *uio;
 651         struct ucred *active_cred;
 652         struct thread *td;
 653         int flags;
 654 {
 655         struct pipe *rpipe;
 656         int error;
 657         int nread = 0;
 658         int size;
 659
 660         rpipe = fp->f_data;
 661         PIPE_LOCK(rpipe);
 662         ++rpipe->pipe_busy;
 663         error = pipelock(rpipe, 1);
 664         if (error)
 665                 goto unlocked_error;
 666
 667 #ifdef MAC
 668         error = mac_pipe_check_read(active_cred, rpipe->pipe_pair);
 669         if (error)
 670                 goto locked_error;
 671 #endif
 672         if (amountpipekva > (3 * maxpipekva) / 4) {
 673                 if (!(rpipe->pipe_state & PIPE_DIRECTW) &&
 674                         (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
 675                         (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
 676                         (piperesizeallowed == 1)) {
 677                         PIPE_UNLOCK(rpipe);
 678                         pipespace(rpipe, SMALL_PIPE_SIZE);
 679                         PIPE_LOCK(rpipe);
 680                 }
 681         }
 682
 683         while (uio->uio_resid) {
 684                 /*
 685                  * normal pipe buffer receive
 686                  */
 687                 if (rpipe->pipe_buffer.cnt > 0) {
 688                         size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
 689                         if (size > rpipe->pipe_buffer.cnt)
 690                                 size = rpipe->pipe_buffer.cnt;
 691                         if (size > uio->uio_resid)
 692                                 size = uio->uio_resid;
 693
 694                         PIPE_UNLOCK(rpipe);
 695                         error = uiomove(
 696                             &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
 697                             size, uio);
 698                         PIPE_LOCK(rpipe);
 699                         if (error)
 700                                 break;
 701
 702                         rpipe->pipe_buffer.out += size;
 703                         if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
 704                                 rpipe->pipe_buffer.out = 0;
 705
 706                         rpipe->pipe_buffer.cnt -= size;
 707
 708                         /*
 709                          * If there is no more to read in the pipe, reset
 710                          * its pointers to the beginning.  This improves
 711                          * cache hit stats.
 712                          */
 713                         if (rpipe->pipe_buffer.cnt == 0) {
 714                                 rpipe->pipe_buffer.in = 0;
 715                                 rpipe->pipe_buffer.out = 0;
 716                         }
 717                         nread += size;
 718 #ifndef PIPE_NODIRECT
 719                 /*
 720                  * Direct copy, bypassing a kernel buffer.
 721                  */
 722                 } else if ((size = rpipe->pipe_map.cnt) &&
 723                            (rpipe->pipe_state & PIPE_DIRECTW)) {
 724                         if (size > uio->uio_resid)
 725                                 size = (u_int) uio->uio_resid;
 726
 727                         PIPE_UNLOCK(rpipe);
 728                         error = uiomove_fromphys(rpipe->pipe_map.ms,
 729                             rpipe->pipe_map.pos, size, uio);
 730                         PIPE_LOCK(rpipe);
 731                         if (error)
 732                                 break;
 733                         nread += size;
 734                         rpipe->pipe_map.pos += size;
 735                         rpipe->pipe_map.cnt -= size;
 736                         if (rpipe->pipe_map.cnt == 0) {
 737                                 rpipe->pipe_state &= ~(PIPE_DIRECTW|PIPE_WANTW);
 738                                 wakeup(rpipe);
 739                         }
 740 #endif
 741                 } else {
 742                         /*
 743                          * detect EOF condition
 744                          * read returns 0 on EOF, no need to set error
 745                          */
 746                         if (rpipe->pipe_state & PIPE_EOF)
 747                                 break;
 748
 749                         /*
 750                          * If the "write-side" has been blocked, wake it up now.
 751                          */
 752                         if (rpipe->pipe_state & PIPE_WANTW) {
 753                                 rpipe->pipe_state &= ~PIPE_WANTW;
 754                                 wakeup(rpipe);
 755                         }
 756
 757                         /*
 758                          * Break if some data was read.
 759                          */
 760                         if (nread > 0)
 761                                 break;
 762
 763                         /*
 764                          * Unlock the pipe buffer for our remaining processing.
 765                          * We will either break out with an error or we will
 766                          * sleep and relock to loop.
 767                          */
 768                         pipeunlock(rpipe);
 769
 770                         /*
 771                          * Handle non-blocking mode operation or
 772                          * wait for more data.
 773                          */
 774                         if (fp->f_flag & FNONBLOCK) {
 775                                 error = EAGAIN;
 776                         } else {
 777                                 rpipe->pipe_state |= PIPE_WANTR;
 778                                 if ((error = msleep(rpipe, PIPE_MTX(rpipe),
 779                                     PRIBIO | PCATCH,
 780                                     "piperd", 0)) == 0)
 781                                         error = pipelock(rpipe, 1);
 782                         }
 783                         if (error)
 784                                 goto unlocked_error;
 785                 }
 786         }
 787 #ifdef MAC
 788 locked_error:
 789 #endif
 790         pipeunlock(rpipe);
 791
 792         /* XXX: should probably do this before getting any locks. */
 793         if (error == 0)
 794                 vfs_timestamp(&rpipe->pipe_atime);
 795 unlocked_error:
 796         --rpipe->pipe_busy;
 797
 798         /*
 799          * PIPE_WANT processing only makes sense if pipe_busy is 0.
 800          */
 801         if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
 802                 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
 803                 wakeup(rpipe);
 804         } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
 805                 /*
 806                  * Handle write blocking hysteresis.
 807                  */
 808                 if (rpipe->pipe_state & PIPE_WANTW) {
 809                         rpipe->pipe_state &= ~PIPE_WANTW;
 810                         wakeup(rpipe);
 811                 }
 812         }
 813
 814         if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
 815                 pipeselwakeup(rpipe);
 816
 817         PIPE_UNLOCK(rpipe);
 818         return (error);
 819 }
 820
 821 #ifndef PIPE_NODIRECT
 822 /*
 823  * Map the sending processes' buffer into kernel space and wire it.
 824  * This is similar to a physical write operation.
 825  */
 826 static int
 827 pipe_build_write_buffer(wpipe, uio)
 828         struct pipe *wpipe;
 829         struct uio *uio;
 830 {
 831         u_int size;
 832         int i;
 833
 834         PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED);
 835         KASSERT(wpipe->pipe_state & PIPE_DIRECTW,
 836                 ("Clone attempt on non-direct write pipe!"));
 837
 838         if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size)
 839                 size = wpipe->pipe_buffer.size;
 840         else
 841                 size = uio->uio_iov->iov_len;
 842
 843         if ((i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
 844             (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ,
 845             wpipe->pipe_map.ms, PIPENPAGES)) < 0)
 846                 return (EFAULT);
 847
 848 /*
 849  * set up the control block
 850  */
 851         wpipe->pipe_map.npages = i;
 852         wpipe->pipe_map.pos =
 853             ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK;
 854         wpipe->pipe_map.cnt = size;
 855
 856 /*
 857  * and update the uio data
 858  */
 859
 860         uio->uio_iov->iov_len -= size;
 861         uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size;
 862         if (uio->uio_iov->iov_len == 0)
 863                 uio->uio_iov++;
 864         uio->uio_resid -= size;
 865         uio->uio_offset += size;
 866         return (0);
 867 }
 868
 869 /*
 870  * unmap and unwire the process buffer
 871  */
 872 static void
 873 pipe_destroy_write_buffer(wpipe)
 874         struct pipe *wpipe;
 875 {
 876
 877         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 878         vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages);
 879         wpipe->pipe_map.npages = 0;
 880 }
 881
 882 /*
 883  * In the case of a signal, the writing process might go away.  This
 884  * code copies the data into the circular buffer so that the source
 885  * pages can be freed without loss of data.
 886  */
 887 static void
 888 pipe_clone_write_buffer(wpipe)
 889         struct pipe *wpipe;
 890 {
 891         struct uio uio;
 892         struct iovec iov;
 893         int size;
 894         int pos;
 895
 896         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 897         size = wpipe->pipe_map.cnt;
 898         pos = wpipe->pipe_map.pos;
 899
 900         wpipe->pipe_buffer.in = size;
 901         wpipe->pipe_buffer.out = 0;
 902         wpipe->pipe_buffer.cnt = size;
 903         wpipe->pipe_state &= ~PIPE_DIRECTW;
 904
 905         PIPE_UNLOCK(wpipe);
 906         iov.iov_base = wpipe->pipe_buffer.buffer;
 907         iov.iov_len = size;
 908         uio.uio_iov = &iov;
 909         uio.uio_iovcnt = 1;
 910         uio.uio_offset = 0;
 911         uio.uio_resid = size;
 912         uio.uio_segflg = UIO_SYSSPACE;
 913         uio.uio_rw = UIO_READ;
 914         uio.uio_td = curthread;
 915         uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio);
 916         PIPE_LOCK(wpipe);
 917         pipe_destroy_write_buffer(wpipe);
 918 }
 919
 920 /*
 921  * This implements the pipe buffer write mechanism.  Note that only
 922  * a direct write OR a normal pipe write can be pending at any given time.
 923  * If there are any characters in the pipe buffer, the direct write will
 924  * be deferred until the receiving process grabs all of the bytes from
 925  * the pipe buffer.  Then the direct mapping write is set-up.
 926  */
 927 static int
 928 pipe_direct_write(wpipe, uio)
 929         struct pipe *wpipe;
 930         struct uio *uio;
 931 {
 932         int error;
 933
 934 retry:
 935         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 936         error = pipelock(wpipe, 1);
 937         if (wpipe->pipe_state & PIPE_EOF)
 938                 error = EPIPE;
 939         if (error) {
 940                 pipeunlock(wpipe);
 941                 goto error1;
 942         }
 943         while (wpipe->pipe_state & PIPE_DIRECTW) {
 944                 if (wpipe->pipe_state & PIPE_WANTR) {
 945                         wpipe->pipe_state &= ~PIPE_WANTR;
 946                         wakeup(wpipe);
 947                 }
 948                 pipeselwakeup(wpipe);
 949                 wpipe->pipe_state |= PIPE_WANTW;
 950                 pipeunlock(wpipe);
 951                 error = msleep(wpipe, PIPE_MTX(wpipe),
 952                     PRIBIO | PCATCH, "pipdww", 0);
 953                 if (error)
 954                         goto error1;
 955                 else
 956                         goto retry;
 957         }
 958         wpipe->pipe_map.cnt = 0;        /* transfer not ready yet */
 959         if (wpipe->pipe_buffer.cnt > 0) {
 960                 if (wpipe->pipe_state & PIPE_WANTR) {
 961                         wpipe->pipe_state &= ~PIPE_WANTR;
 962                         wakeup(wpipe);
 963                 }
 964                 pipeselwakeup(wpipe);
 965                 wpipe->pipe_state |= PIPE_WANTW;
 966                 pipeunlock(wpipe);
 967                 error = msleep(wpipe, PIPE_MTX(wpipe),
 968                     PRIBIO | PCATCH, "pipdwc", 0);
 969                 if (error)
 970                         goto error1;
 971                 else
 972                         goto retry;
 973         }
 974
 975         wpipe->pipe_state |= PIPE_DIRECTW;
 976
 977         PIPE_UNLOCK(wpipe);
 978         error = pipe_build_write_buffer(wpipe, uio);
 979         PIPE_LOCK(wpipe);
 980         if (error) {
 981                 wpipe->pipe_state &= ~PIPE_DIRECTW;
 982                 pipeunlock(wpipe);
 983                 goto error1;
 984         }
 985
 986         error = 0;
 987         while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
 988                 if (wpipe->pipe_state & PIPE_EOF) {
 989                         pipe_destroy_write_buffer(wpipe);
 990                         pipeselwakeup(wpipe);
 991                         pipeunlock(wpipe);
 992                         error = EPIPE;
 993                         goto error1;
 994                 }
 995                 if (wpipe->pipe_state & PIPE_WANTR) {
 996                         wpipe->pipe_state &= ~PIPE_WANTR;
 997                         wakeup(wpipe);
 998                 }
 999                 pipeselwakeup(wpipe);
1000                 wpipe->pipe_state |= PIPE_WANTW;
1001                 pipeunlock(wpipe);
1002                 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
1003                     "pipdwt", 0);
1004                 pipelock(wpipe, 0);
1005         }
1006
1007         if (wpipe->pipe_state & PIPE_EOF)
1008                 error = EPIPE;
1009         if (wpipe->pipe_state & PIPE_DIRECTW) {
1010                 /*
1011                  * this bit of trickery substitutes a kernel buffer for
1012                  * the process that might be going away.
1013                  */
1014                 pipe_clone_write_buffer(wpipe);
1015         } else {
1016                 pipe_destroy_write_buffer(wpipe);
1017         }
1018         pipeunlock(wpipe);
1019         return (error);
1020
1021 error1:
1022         wakeup(wpipe);
1023         return (error);
1024 }
1025 #endif
1026
1027 static int
1028 pipe_write(fp, uio, active_cred, flags, td)
1029         struct file *fp;
1030         struct uio *uio;
1031         struct ucred *active_cred;
1032         struct thread *td;
1033         int flags;
1034 {
1035         int error = 0;
1036         int desiredsize;
1037         ssize_t orig_resid;
1038         struct pipe *wpipe, *rpipe;
1039
1040         rpipe = fp->f_data;
1041         wpipe = PIPE_PEER(rpipe);
1042         PIPE_LOCK(rpipe);
1043         error = pipelock(wpipe, 1);
1044         if (error) {
1045                 PIPE_UNLOCK(rpipe);
1046                 return (error);
1047         }
1048         /*
1049          * detect loss of pipe read side, issue SIGPIPE if lost.
1050          */
1051         if (wpipe->pipe_present != PIPE_ACTIVE ||
1052             (wpipe->pipe_state & PIPE_EOF)) {
1053                 pipeunlock(wpipe);
1054                 PIPE_UNLOCK(rpipe);
1055                 return (EPIPE);
1056         }
1057 #ifdef MAC
1058         error = mac_pipe_check_write(active_cred, wpipe->pipe_pair);
1059         if (error) {
1060                 pipeunlock(wpipe);
1061                 PIPE_UNLOCK(rpipe);
1062                 return (error);
1063         }
1064 #endif
1065         ++wpipe->pipe_busy;
1066
1067         /* Choose a larger size if it's advantageous */
1068         desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size);
1069         while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) {
1070                 if (piperesizeallowed != 1)
1071                         break;
1072                 if (amountpipekva > maxpipekva / 2)
1073                         break;
1074                 if (desiredsize == BIG_PIPE_SIZE)
1075                         break;
1076                 desiredsize = desiredsize * 2;
1077         }
1078
1079         /* Choose a smaller size if we're in a OOM situation */
1080         if ((amountpipekva > (3 * maxpipekva) / 4) &&
1081                 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
1082                 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
1083                 (piperesizeallowed == 1))
1084                 desiredsize = SMALL_PIPE_SIZE;
1085
1086         /* Resize if the above determined that a new size was necessary */
1087         if ((desiredsize != wpipe->pipe_buffer.size) &&
1088                 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) {
1089                 PIPE_UNLOCK(wpipe);
1090                 pipespace(wpipe, desiredsize);
1091                 PIPE_LOCK(wpipe);
1092         }
1093         if (wpipe->pipe_buffer.size == 0) {
1094                 /*
1095                  * This can only happen for reverse direction use of pipes
1096                  * in a complete OOM situation.
1097                  */
1098                 error = ENOMEM;
1099                 --wpipe->pipe_busy;
1100                 pipeunlock(wpipe);
1101                 PIPE_UNLOCK(wpipe);
1102                 return (error);
1103         }
1104
1105         pipeunlock(wpipe);
1106
1107         orig_resid = uio->uio_resid;
1108
1109         while (uio->uio_resid) {
1110                 int space;
1111
1112                 pipelock(wpipe, 0);
1113                 if (wpipe->pipe_state & PIPE_EOF) {
1114                         pipeunlock(wpipe);
1115                         error = EPIPE;
1116                         break;
1117                 }
1118 #ifndef PIPE_NODIRECT
1119                 /*
1120                  * If the transfer is large, we can gain performance if
1121                  * we do process-to-process copies directly.
1122                  * If the write is non-blocking, we don't use the
1123                  * direct write mechanism.
1124                  *
1125                  * The direct write mechanism will detect the reader going
1126                  * away on us.
1127                  */
1128                 if (uio->uio_segflg == UIO_USERSPACE &&
1129                     uio->uio_iov->iov_len >= PIPE_MINDIRECT &&
1130                     wpipe->pipe_buffer.size >= PIPE_MINDIRECT &&
1131                     (fp->f_flag & FNONBLOCK) == 0) {
1132                         pipeunlock(wpipe);
1133                         error = pipe_direct_write(wpipe, uio);
1134                         if (error)
1135                                 break;
1136                         continue;
1137                 }
1138 #endif
1139
1140                 /*
1141                  * Pipe buffered writes cannot be coincidental with
1142                  * direct writes.  We wait until the currently executing
1143                  * direct write is completed before we start filling the
1144                  * pipe buffer.  We break out if a signal occurs or the
1145                  * reader goes away.
1146                  */
1147                 if (wpipe->pipe_state & PIPE_DIRECTW) {
1148                         if (wpipe->pipe_state & PIPE_WANTR) {
1149                                 wpipe->pipe_state &= ~PIPE_WANTR;
1150                                 wakeup(wpipe);
1151                         }
1152                         pipeselwakeup(wpipe);
1153                         wpipe->pipe_state |= PIPE_WANTW;
1154                         pipeunlock(wpipe);
1155                         error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH,
1156                             "pipbww", 0);
1157                         if (error)
1158                                 break;
1159                         else
1160                                 continue;
1161                 }
1162
1163                 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1164
1165                 /* Writes of size <= PIPE_BUF must be atomic. */
1166                 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
1167                         space = 0;
1168
1169                 if (space > 0) {
1170                         int size;       /* Transfer size */
1171                         int segsize;    /* first segment to transfer */
1172
1173                         /*
1174                          * Transfer size is minimum of uio transfer
1175                          * and free space in pipe buffer.
1176                          */
1177                         if (space > uio->uio_resid)
1178                                 size = uio->uio_resid;
1179                         else
1180                                 size = space;
1181                         /*
1182                          * First segment to transfer is minimum of
1183                          * transfer size and contiguous space in
1184                          * pipe buffer.  If first segment to transfer
1185                          * is less than the transfer size, we've got
1186                          * a wraparound in the buffer.
1187                          */
1188                         segsize = wpipe->pipe_buffer.size -
1189                                 wpipe->pipe_buffer.in;
1190                         if (segsize > size)
1191                                 segsize = size;
1192
1193                         /* Transfer first segment */
1194
1195                         PIPE_UNLOCK(rpipe);
1196                         error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
1197                                         segsize, uio);
1198                         PIPE_LOCK(rpipe);
1199
1200                         if (error == 0 && segsize < size) {
1201                                 KASSERT(wpipe->pipe_buffer.in + segsize ==
1202                                         wpipe->pipe_buffer.size,
1203                                         ("Pipe buffer wraparound disappeared"));
1204                                 /*
1205                                  * Transfer remaining part now, to
1206                                  * support atomic writes.  Wraparound
1207                                  * happened.
1208                                  */
1209
1210                                 PIPE_UNLOCK(rpipe);
1211                                 error = uiomove(
1212                                     &wpipe->pipe_buffer.buffer[0],
1213                                     size - segsize, uio);
1214                                 PIPE_LOCK(rpipe);
1215                         }
1216                         if (error == 0) {
1217                                 wpipe->pipe_buffer.in += size;
1218                                 if (wpipe->pipe_buffer.in >=
1219                                     wpipe->pipe_buffer.size) {
1220                                         KASSERT(wpipe->pipe_buffer.in ==
1221                                                 size - segsize +
1222                                                 wpipe->pipe_buffer.size,
1223                                                 ("Expected wraparound bad"));
1224                                         wpipe->pipe_buffer.in = size - segsize;
1225                                 }
1226
1227                                 wpipe->pipe_buffer.cnt += size;
1228                                 KASSERT(wpipe->pipe_buffer.cnt <=
1229                                         wpipe->pipe_buffer.size,
1230                                         ("Pipe buffer overflow"));
1231                         }
1232                         pipeunlock(wpipe);
1233                         if (error != 0)
1234                                 break;
1235                 } else {
1236                         /*
1237                          * If the "read-side" has been blocked, wake it up now.
1238                          */
1239                         if (wpipe->pipe_state & PIPE_WANTR) {
1240                                 wpipe->pipe_state &= ~PIPE_WANTR;
1241                                 wakeup(wpipe);
1242                         }
1243
1244                         /*
1245                          * don't block on non-blocking I/O
1246                          */
1247                         if (fp->f_flag & FNONBLOCK) {
1248                                 error = EAGAIN;
1249                                 pipeunlock(wpipe);
1250                                 break;
1251                         }
1252
1253                         /*
1254                          * We have no more space and have something to offer,
1255                          * wake up select/poll.
1256                          */
1257                         pipeselwakeup(wpipe);
1258
1259                         wpipe->pipe_state |= PIPE_WANTW;
1260                         pipeunlock(wpipe);
1261                         error = msleep(wpipe, PIPE_MTX(rpipe),
1262                             PRIBIO | PCATCH, "pipewr", 0);
1263                         if (error != 0)
1264                                 break;
1265                 }
1266         }
1267
1268         pipelock(wpipe, 0);
1269         --wpipe->pipe_busy;
1270
1271         if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1272                 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1273                 wakeup(wpipe);
1274         } else if (wpipe->pipe_buffer.cnt > 0) {
1275                 /*
1276                  * If we have put any characters in the buffer, we wake up
1277                  * the reader.
1278                  */
1279                 if (wpipe->pipe_state & PIPE_WANTR) {
1280                         wpipe->pipe_state &= ~PIPE_WANTR;
1281                         wakeup(wpipe);
1282                 }
1283         }
1284
1285         /*
1286          * Don't return EPIPE if I/O was successful
1287          */
1288         if ((wpipe->pipe_buffer.cnt == 0) &&
1289             (uio->uio_resid == 0) &&
1290             (error == EPIPE)) {
1291                 error = 0;
1292         }
1293
1294         if (error == 0)
1295                 vfs_timestamp(&wpipe->pipe_mtime);
1296
1297         /*
1298          * We have something to offer,
1299          * wake up select/poll.
1300          */
1301         if (wpipe->pipe_buffer.cnt)
1302                 pipeselwakeup(wpipe);
1303
1304         pipeunlock(wpipe);
1305         PIPE_UNLOCK(rpipe);
1306         return (error);
1307 }
1308
1309 /* ARGSUSED */
1310 static int
1311 pipe_truncate(fp, length, active_cred, td)
1312         struct file *fp;
1313         off_t length;
1314         struct ucred *active_cred;
1315         struct thread *td;
1316 {
1317
1318         /* For named pipes call the vnode operation. */
1319         if (fp->f_vnode != NULL)
1320                 return (vnops.fo_truncate(fp, length, active_cred, td));
1321         return (EINVAL);
1322 }
1323
1324 /*
1325  * we implement a very minimal set of ioctls for compatibility with sockets.
1326  */
1327 static int
1328 pipe_ioctl(fp, cmd, data, active_cred, td)
1329         struct file *fp;
1330         u_long cmd;
1331         void *data;
1332         struct ucred *active_cred;
1333         struct thread *td;
1334 {
1335         struct pipe *mpipe = fp->f_data;
1336         int error;
1337
1338         PIPE_LOCK(mpipe);
1339
1340 #ifdef MAC
1341         error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data);
1342         if (error) {
1343                 PIPE_UNLOCK(mpipe);
1344                 return (error);
1345         }
1346 #endif
1347
1348         error = 0;
1349         switch (cmd) {
1350
1351         case FIONBIO:
1352                 break;
1353
1354         case FIOASYNC:
1355                 if (*(int *)data) {
1356                         mpipe->pipe_state |= PIPE_ASYNC;
1357                 } else {
1358                         mpipe->pipe_state &= ~PIPE_ASYNC;
1359                 }
1360                 break;
1361
1362         case FIONREAD:
1363                 if (!(fp->f_flag & FREAD)) {
1364                         *(int *)data = 0;
1365                         PIPE_UNLOCK(mpipe);
1366                         return (0);
1367                 }
1368                 if (mpipe->pipe_state & PIPE_DIRECTW)
1369                         *(int *)data = mpipe->pipe_map.cnt;
1370                 else
1371                         *(int *)data = mpipe->pipe_buffer.cnt;
1372                 break;
1373
1374         case FIOSETOWN:
1375                 PIPE_UNLOCK(mpipe);
1376                 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
1377                 goto out_unlocked;
1378
1379         case FIOGETOWN:
1380                 *(int *)data = fgetown(&mpipe->pipe_sigio);
1381                 break;
1382
1383         /* This is deprecated, FIOSETOWN should be used instead. */
1384         case TIOCSPGRP:
1385                 PIPE_UNLOCK(mpipe);
1386                 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
1387                 goto out_unlocked;
1388
1389         /* This is deprecated, FIOGETOWN should be used instead. */
1390         case TIOCGPGRP:
1391                 *(int *)data = -fgetown(&mpipe->pipe_sigio);
1392                 break;
1393
1394         default:
1395                 error = ENOTTY;
1396                 break;
1397         }
1398         PIPE_UNLOCK(mpipe);
1399 out_unlocked:
1400         return (error);
1401 }
1402
1403 static int
1404 pipe_poll(fp, events, active_cred, td)
1405         struct file *fp;
1406         int events;
1407         struct ucred *active_cred;
1408         struct thread *td;
1409 {
1410         struct pipe *rpipe;
1411         struct pipe *wpipe;
1412         int levents, revents;
1413 #ifdef MAC
1414         int error;
1415 #endif
1416
1417         revents = 0;
1418         rpipe = fp->f_data;
1419         wpipe = PIPE_PEER(rpipe);
1420         PIPE_LOCK(rpipe);
1421 #ifdef MAC
1422         error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair);
1423         if (error)
1424                 goto locked_error;
1425 #endif
1426         if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM))
1427                 if ((rpipe->pipe_state & PIPE_DIRECTW) ||
1428                     (rpipe->pipe_buffer.cnt > 0))
1429                         revents |= events & (POLLIN | POLLRDNORM);
1430
1431         if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM))
1432                 if (wpipe->pipe_present != PIPE_ACTIVE ||
1433                     (wpipe->pipe_state & PIPE_EOF) ||
1434                     (((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
1435                      ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF ||
1436                          wpipe->pipe_buffer.size == 0)))
1437                         revents |= events & (POLLOUT | POLLWRNORM);
1438
1439         levents = events &
1440             (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND);
1441         if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents &&
1442             fp->f_seqcount == rpipe->pipe_wgen)
1443                 events |= POLLINIGNEOF;
1444
1445         if ((events & POLLINIGNEOF) == 0) {
1446                 if (rpipe->pipe_state & PIPE_EOF) {
1447                         revents |= (events & (POLLIN | POLLRDNORM));
1448                         if (wpipe->pipe_present != PIPE_ACTIVE ||
1449                             (wpipe->pipe_state & PIPE_EOF))
1450                                 revents |= POLLHUP;
1451                 }
1452         }
1453
1454         if (revents == 0) {
1455                 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) {
1456                         selrecord(td, &rpipe->pipe_sel);
1457                         if (SEL_WAITING(&rpipe->pipe_sel))
1458                                 rpipe->pipe_state |= PIPE_SEL;
1459                 }
1460
1461                 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) {
1462                         selrecord(td, &wpipe->pipe_sel);
1463                         if (SEL_WAITING(&wpipe->pipe_sel))
1464                                 wpipe->pipe_state |= PIPE_SEL;
1465                 }
1466         }
1467 #ifdef MAC
1468 locked_error:
1469 #endif
1470         PIPE_UNLOCK(rpipe);
1471
1472         return (revents);
1473 }
1474
1475 /*
1476  * We shouldn't need locks here as we're doing a read and this should
1477  * be a natural race.
1478  */
1479 static int
1480 pipe_stat(fp, ub, active_cred, td)
1481         struct file *fp;
1482         struct stat *ub;
1483         struct ucred *active_cred;
1484         struct thread *td;
1485 {
1486         struct pipe *pipe;
1487         int new_unr;
1488 #ifdef MAC
1489         int error;
1490 #endif
1491
1492         pipe = fp->f_data;
1493         PIPE_LOCK(pipe);
1494 #ifdef MAC
1495         error = mac_pipe_check_stat(active_cred, pipe->pipe_pair);
1496         if (error) {
1497                 PIPE_UNLOCK(pipe);
1498                 return (error);
1499         }
1500 #endif
1501
1502         /* For named pipes ask the underlying filesystem. */
1503         if (pipe->pipe_state & PIPE_NAMED) {
1504                 PIPE_UNLOCK(pipe);
1505                 return (vnops.fo_stat(fp, ub, active_cred, td));
1506         }
1507
1508         /*
1509          * Lazily allocate an inode number for the pipe.  Most pipe
1510          * users do not call fstat(2) on the pipe, which means that
1511          * postponing the inode allocation until it is must be
1512          * returned to userland is useful.  If alloc_unr failed,
1513          * assign st_ino zero instead of returning an error.
1514          * Special pipe_ino values:
1515          *  -1 - not yet initialized;
1516          *  0  - alloc_unr failed, return 0 as st_ino forever.
1517          */
1518         if (pipe->pipe_ino == (ino_t)-1) {
1519                 new_unr = alloc_unr(pipeino_unr);
1520                 if (new_unr != -1)
1521                         pipe->pipe_ino = new_unr;
1522                 else
1523                         pipe->pipe_ino = 0;
1524         }
1525         PIPE_UNLOCK(pipe);
1526
1527         bzero(ub, sizeof(*ub));
1528         ub->st_mode = S_IFIFO;
1529         ub->st_blksize = PAGE_SIZE;
1530         if (pipe->pipe_state & PIPE_DIRECTW)
1531                 ub->st_size = pipe->pipe_map.cnt;
1532         else
1533                 ub->st_size = pipe->pipe_buffer.cnt;
1534         ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
1535         ub->st_atim = pipe->pipe_atime;
1536         ub->st_mtim = pipe->pipe_mtime;
1537         ub->st_ctim = pipe->pipe_ctime;
1538         ub->st_uid = fp->f_cred->cr_uid;
1539         ub->st_gid = fp->f_cred->cr_gid;
1540         ub->st_dev = pipedev_ino;
1541         ub->st_ino = pipe->pipe_ino;
1542         /*
1543          * Left as 0: st_nlink, st_rdev, st_flags, st_gen.
1544          */
1545         return (0);
1546 }
1547
1548 /* ARGSUSED */
1549 static int
1550 pipe_close(fp, td)
1551         struct file *fp;
1552         struct thread *td;
1553 {
1554
1555         if (fp->f_vnode != NULL)
1556                 return vnops.fo_close(fp, td);
1557         fp->f_ops = &badfileops;
1558         pipe_dtor(fp->f_data);
1559         fp->f_data = NULL;
1560         return (0);
1561 }
1562
1563 static int
1564 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td)
1565 {
1566         struct pipe *cpipe;
1567         int error;
1568
1569         cpipe = fp->f_data;
1570         if (cpipe->pipe_state & PIPE_NAMED)
1571                 error = vn_chmod(fp, mode, active_cred, td);
1572         else
1573                 error = invfo_chmod(fp, mode, active_cred, td);
1574         return (error);
1575 }
1576
1577 static int
1578 pipe_chown(fp, uid, gid, active_cred, td)
1579         struct file *fp;
1580         uid_t uid;
1581         gid_t gid;
1582         struct ucred *active_cred;
1583         struct thread *td;
1584 {
1585         struct pipe *cpipe;
1586         int error;
1587
1588         cpipe = fp->f_data;
1589         if (cpipe->pipe_state & PIPE_NAMED)
1590                 error = vn_chown(fp, uid, gid, active_cred, td);
1591         else
1592                 error = invfo_chown(fp, uid, gid, active_cred, td);
1593         return (error);
1594 }
1595
1596 static void
1597 pipe_free_kmem(cpipe)
1598         struct pipe *cpipe;
1599 {
1600
1601         KASSERT(!mtx_owned(PIPE_MTX(cpipe)),
1602             ("pipe_free_kmem: pipe mutex locked"));
1603
1604         if (cpipe->pipe_buffer.buffer != NULL) {
1605                 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size);
1606                 vm_map_remove(pipe_map,
1607                     (vm_offset_t)cpipe->pipe_buffer.buffer,
1608                     (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size);
1609                 cpipe->pipe_buffer.buffer = NULL;
1610         }
1611 #ifndef PIPE_NODIRECT
1612         {
1613                 cpipe->pipe_map.cnt = 0;
1614                 cpipe->pipe_map.pos = 0;
1615                 cpipe->pipe_map.npages = 0;
1616         }
1617 #endif
1618 }
1619
1620 /*
1621  * shutdown the pipe
1622  */
1623 static void
1624 pipeclose(cpipe)
1625         struct pipe *cpipe;
1626 {
1627         struct pipepair *pp;
1628         struct pipe *ppipe;
1629
1630         KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL"));
1631
1632         PIPE_LOCK(cpipe);
1633         pipelock(cpipe, 0);
1634         pp = cpipe->pipe_pair;
1635
1636         pipeselwakeup(cpipe);
1637
1638         /*
1639          * If the other side is blocked, wake it up saying that
1640          * we want to close it down.
1641          */
1642         cpipe->pipe_state |= PIPE_EOF;
1643         while (cpipe->pipe_busy) {
1644                 wakeup(cpipe);
1645                 cpipe->pipe_state |= PIPE_WANT;
1646                 pipeunlock(cpipe);
1647                 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
1648                 pipelock(cpipe, 0);
1649         }
1650
1651
1652         /*
1653          * Disconnect from peer, if any.
1654          */
1655         ppipe = cpipe->pipe_peer;
1656         if (ppipe->pipe_present == PIPE_ACTIVE) {
1657                 pipeselwakeup(ppipe);
1658
1659                 ppipe->pipe_state |= PIPE_EOF;
1660                 wakeup(ppipe);
1661                 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0);
1662         }
1663
1664         /*
1665          * Mark this endpoint as free.  Release kmem resources.  We
1666          * don't mark this endpoint as unused until we've finished
1667          * doing that, or the pipe might disappear out from under
1668          * us.
1669          */
1670         PIPE_UNLOCK(cpipe);
1671         pipe_free_kmem(cpipe);
1672         PIPE_LOCK(cpipe);
1673         cpipe->pipe_present = PIPE_CLOSING;
1674         pipeunlock(cpipe);
1675
1676         /*
1677          * knlist_clear() may sleep dropping the PIPE_MTX. Set the
1678          * PIPE_FINALIZED, that allows other end to free the
1679          * pipe_pair, only after the knotes are completely dismantled.
1680          */
1681         knlist_clear(&cpipe->pipe_sel.si_note, 1);
1682         cpipe->pipe_present = PIPE_FINALIZED;
1683         seldrain(&cpipe->pipe_sel);
1684         knlist_destroy(&cpipe->pipe_sel.si_note);
1685
1686         /*
1687          * If both endpoints are now closed, release the memory for the
1688          * pipe pair.  If not, unlock.
1689          */
1690         if (ppipe->pipe_present == PIPE_FINALIZED) {
1691                 PIPE_UNLOCK(cpipe);
1692 #ifdef MAC
1693                 mac_pipe_destroy(pp);
1694 #endif
1695                 uma_zfree(pipe_zone, cpipe->pipe_pair);
1696         } else
1697                 PIPE_UNLOCK(cpipe);
1698 }
1699
1700 /*ARGSUSED*/
1701 static int
1702 pipe_kqfilter(struct file *fp, struct knote *kn)
1703 {
1704         struct pipe *cpipe;
1705
1706         /*
1707          * If a filter is requested that is not supported by this file
1708          * descriptor, don't return an error, but also don't ever generate an
1709          * event.
1710          */
1711         if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) {
1712                 kn->kn_fop = &pipe_nfiltops;
1713                 return (0);
1714         }
1715         if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) {
1716                 kn->kn_fop = &pipe_nfiltops;
1717                 return (0);
1718         }
1719         cpipe = fp->f_data;
1720         PIPE_LOCK(cpipe);
1721         switch (kn->kn_filter) {
1722         case EVFILT_READ:
1723                 kn->kn_fop = &pipe_rfiltops;
1724                 break;
1725         case EVFILT_WRITE:
1726                 kn->kn_fop = &pipe_wfiltops;
1727                 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) {
1728                         /* other end of pipe has been closed */
1729                         PIPE_UNLOCK(cpipe);
1730                         return (EPIPE);
1731                 }
1732                 cpipe = PIPE_PEER(cpipe);
1733                 break;
1734         default:
1735                 PIPE_UNLOCK(cpipe);
1736                 return (EINVAL);
1737         }
1738
1739         kn->kn_hook = cpipe;
1740         knlist_add(&cpipe->pipe_sel.si_note, kn, 1);
1741         PIPE_UNLOCK(cpipe);
1742         return (0);
1743 }
1744
1745 static void
1746 filt_pipedetach(struct knote *kn)
1747 {
1748         struct pipe *cpipe = kn->kn_hook;
1749
1750         PIPE_LOCK(cpipe);
1751         knlist_remove(&cpipe->pipe_sel.si_note, kn, 1);
1752         PIPE_UNLOCK(cpipe);
1753 }
1754
1755 /*ARGSUSED*/
1756 static int
1757 filt_piperead(struct knote *kn, long hint)
1758 {
1759         struct pipe *rpipe = kn->kn_hook;
1760         struct pipe *wpipe = rpipe->pipe_peer;
1761         int ret;
1762
1763         PIPE_LOCK(rpipe);
1764         kn->kn_data = rpipe->pipe_buffer.cnt;
1765         if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
1766                 kn->kn_data = rpipe->pipe_map.cnt;
1767
1768         if ((rpipe->pipe_state & PIPE_EOF) ||
1769             wpipe->pipe_present != PIPE_ACTIVE ||
1770             (wpipe->pipe_state & PIPE_EOF)) {
1771                 kn->kn_flags |= EV_EOF;
1772                 PIPE_UNLOCK(rpipe);
1773                 return (1);
1774         }
1775         ret = kn->kn_data > 0;
1776         PIPE_UNLOCK(rpipe);
1777         return ret;
1778 }
1779
1780 /*ARGSUSED*/
1781 static int
1782 filt_pipewrite(struct knote *kn, long hint)
1783 {
1784         struct pipe *wpipe;
1785
1786         wpipe = kn->kn_hook;
1787         PIPE_LOCK(wpipe);
1788         if (wpipe->pipe_present != PIPE_ACTIVE ||
1789             (wpipe->pipe_state & PIPE_EOF)) {
1790                 kn->kn_data = 0;
1791                 kn->kn_flags |= EV_EOF;
1792                 PIPE_UNLOCK(wpipe);
1793                 return (1);
1794         }
1795         kn->kn_data = (wpipe->pipe_buffer.size > 0) ?
1796             (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF;
1797         if (wpipe->pipe_state & PIPE_DIRECTW)
1798                 kn->kn_data = 0;
1799
1800         PIPE_UNLOCK(wpipe);
1801         return (kn->kn_data >= PIPE_BUF);
1802 }
1803
1804 static void
1805 filt_pipedetach_notsup(struct knote *kn)
1806 {
1807
1808 }
1809
1810 static int
1811 filt_pipenotsup(struct knote *kn, long hint)
1812 {
1813
1814         return (0);
1815 }