sys/kern/sys_pipe.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-4-Clause
   3  *
   4  * Copyright (c) 1996 John S. Dyson
   5  * Copyright (c) 2012 Giovanni Trematerra
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice immediately at the beginning of the file, without modification,
  13  *    this list of conditions, and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 3. Absolutely no warranty of function or purpose is made by the author
  18  *    John S. Dyson.
  19  * 4. Modifications may be freely made to this file if the above conditions
  20  *    are met.
  21  */
  22
  23 /*
  24  * This file contains a high-performance replacement for the socket-based
  25  * pipes scheme originally used in FreeBSD/4.4Lite.  It does not support
  26  * all features of sockets, but does do everything that pipes normally
  27  * do.
  28  */
  29
  30 /*
  31  * This code has two modes of operation, a small write mode and a large
  32  * write mode.  The small write mode acts like conventional pipes with
  33  * a kernel buffer.  If the buffer is less than PIPE_MINDIRECT, then the
  34  * "normal" pipe buffering is done.  If the buffer is between PIPE_MINDIRECT
  35  * and PIPE_SIZE in size, the sending process pins the underlying pages in
  36  * memory, and the receiving process copies directly from these pinned pages
  37  * in the sending process.
  38  *
  39  * If the sending process receives a signal, it is possible that it will
  40  * go away, and certainly its address space can change, because control
  41  * is returned back to the user-mode side.  In that case, the pipe code
  42  * arranges to copy the buffer supplied by the user process, to a pageable
  43  * kernel buffer, and the receiving process will grab the data from the
  44  * pageable kernel buffer.  Since signals don't happen all that often,
  45  * the copy operation is normally eliminated.
  46  *
  47  * The constant PIPE_MINDIRECT is chosen to make sure that buffering will
  48  * happen for small transfers so that the system will not spend all of
  49  * its time context switching.
  50  *
  51  * In order to limit the resource use of pipes, two sysctls exist:
  52  *
  53  * kern.ipc.maxpipekva - This is a hard limit on the amount of pageable
  54  * address space available to us in pipe_map. This value is normally
  55  * autotuned, but may also be loader tuned.
  56  *
  57  * kern.ipc.pipekva - This read-only sysctl tracks the current amount of
  58  * memory in use by pipes.
  59  *
  60  * Based on how large pipekva is relative to maxpipekva, the following
  61  * will happen:
  62  *
  63  * 0% - 50%:
  64  *     New pipes are given 16K of memory backing, pipes may dynamically
  65  *     grow to as large as 64K where needed.
  66  * 50% - 75%:
  67  *     New pipes are given 4K (or PAGE_SIZE) of memory backing,
  68  *     existing pipes may NOT grow.
  69  * 75% - 100%:
  70  *     New pipes are given 4K (or PAGE_SIZE) of memory backing,
  71  *     existing pipes will be shrunk down to 4K whenever possible.
  72  *
  73  * Resizing may be disabled by setting kern.ipc.piperesizeallowed=0.  If
  74  * that is set,  the only resize that will occur is the 0 -> SMALL_PIPE_SIZE
  75  * resize which MUST occur for reverse-direction pipes when they are
  76  * first used.
  77  *
  78  * Additional information about the current state of pipes may be obtained
  79  * from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail,
  80  * and kern.ipc.piperesizefail.
  81  *
  82  * Locking rules:  There are two locks present here:  A mutex, used via
  83  * PIPE_LOCK, and a flag, used via pipelock().  All locking is done via
  84  * the flag, as mutexes can not persist over uiomove.  The mutex
  85  * exists only to guard access to the flag, and is not in itself a
  86  * locking mechanism.  Also note that there is only a single mutex for
  87  * both directions of a pipe.
  88  *
  89  * As pipelock() may have to sleep before it can acquire the flag, it
  90  * is important to reread all data after a call to pipelock(); everything
  91  * in the structure may have changed.
  92  */
  93
  94 #include <sys/cdefs.h>
  95 __FBSDID("$FreeBSD$");
  96
  97 #include <sys/param.h>
  98 #include <sys/systm.h>
  99 #include <sys/conf.h>
 100 #include <sys/fcntl.h>
 101 #include <sys/file.h>
 102 #include <sys/filedesc.h>
 103 #include <sys/filio.h>
 104 #include <sys/kernel.h>
 105 #include <sys/lock.h>
 106 #include <sys/mutex.h>
 107 #include <sys/ttycom.h>
 108 #include <sys/stat.h>
 109 #include <sys/malloc.h>
 110 #include <sys/poll.h>
 111 #include <sys/selinfo.h>
 112 #include <sys/signalvar.h>
 113 #include <sys/syscallsubr.h>
 114 #include <sys/sysctl.h>
 115 #include <sys/sysproto.h>
 116 #include <sys/pipe.h>
 117 #include <sys/proc.h>
 118 #include <sys/vnode.h>
 119 #include <sys/uio.h>
 120 #include <sys/user.h>
 121 #include <sys/event.h>
 122
 123 #include <security/mac/mac_framework.h>
 124
 125 #include <vm/vm.h>
 126 #include <vm/vm_param.h>
 127 #include <vm/vm_object.h>
 128 #include <vm/vm_kern.h>
 129 #include <vm/vm_extern.h>
 130 #include <vm/pmap.h>
 131 #include <vm/vm_map.h>
 132 #include <vm/vm_page.h>
 133 #include <vm/uma.h>
 134
 135 /*
 136  * Use this define if you want to disable *fancy* VM things.  Expect an
 137  * approx 30% decrease in transfer rate.  This could be useful for
 138  * NetBSD or OpenBSD.
 139  */
 140 /* #define PIPE_NODIRECT */
 141
 142 #define PIPE_PEER(pipe) \
 143         (((pipe)->pipe_state & PIPE_NAMED) ? (pipe) : ((pipe)->pipe_peer))
 144
 145 /*
 146  * interfaces to the outside world
 147  */
 148 static fo_rdwr_t        pipe_read;
 149 static fo_rdwr_t        pipe_write;
 150 static fo_truncate_t    pipe_truncate;
 151 static fo_ioctl_t       pipe_ioctl;
 152 static fo_poll_t        pipe_poll;
 153 static fo_kqfilter_t    pipe_kqfilter;
 154 static fo_stat_t        pipe_stat;
 155 static fo_close_t       pipe_close;
 156 static fo_chmod_t       pipe_chmod;
 157 static fo_chown_t       pipe_chown;
 158 static fo_fill_kinfo_t  pipe_fill_kinfo;
 159
 160 struct fileops pipeops = {
 161         .fo_read = pipe_read,
 162         .fo_write = pipe_write,
 163         .fo_truncate = pipe_truncate,
 164         .fo_ioctl = pipe_ioctl,
 165         .fo_poll = pipe_poll,
 166         .fo_kqfilter = pipe_kqfilter,
 167         .fo_stat = pipe_stat,
 168         .fo_close = pipe_close,
 169         .fo_chmod = pipe_chmod,
 170         .fo_chown = pipe_chown,
 171         .fo_sendfile = invfo_sendfile,
 172         .fo_fill_kinfo = pipe_fill_kinfo,
 173         .fo_flags = DFLAG_PASSABLE
 174 };
 175
 176 static void     filt_pipedetach(struct knote *kn);
 177 static void     filt_pipedetach_notsup(struct knote *kn);
 178 static int      filt_pipenotsup(struct knote *kn, long hint);
 179 static int      filt_piperead(struct knote *kn, long hint);
 180 static int      filt_pipewrite(struct knote *kn, long hint);
 181
 182 static struct filterops pipe_nfiltops = {
 183         .f_isfd = 1,
 184         .f_detach = filt_pipedetach_notsup,
 185         .f_event = filt_pipenotsup
 186 };
 187 static struct filterops pipe_rfiltops = {
 188         .f_isfd = 1,
 189         .f_detach = filt_pipedetach,
 190         .f_event = filt_piperead
 191 };
 192 static struct filterops pipe_wfiltops = {
 193         .f_isfd = 1,
 194         .f_detach = filt_pipedetach,
 195         .f_event = filt_pipewrite
 196 };
 197
 198 /*
 199  * Default pipe buffer size(s), this can be kind-of large now because pipe
 200  * space is pageable.  The pipe code will try to maintain locality of
 201  * reference for performance reasons, so small amounts of outstanding I/O
 202  * will not wipe the cache.
 203  */
 204 #define MINPIPESIZE (PIPE_SIZE/3)
 205 #define MAXPIPESIZE (2*PIPE_SIZE/3)
 206
 207 static long amountpipekva;
 208 static int pipefragretry;
 209 static int pipeallocfail;
 210 static int piperesizefail;
 211 static int piperesizeallowed = 1;
 212
 213 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
 214            &maxpipekva, 0, "Pipe KVA limit");
 215 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD,
 216            &amountpipekva, 0, "Pipe KVA usage");
 217 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD,
 218           &pipefragretry, 0, "Pipe allocation retries due to fragmentation");
 219 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD,
 220           &pipeallocfail, 0, "Pipe allocation failures");
 221 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD,
 222           &piperesizefail, 0, "Pipe resize failures");
 223 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW,
 224           &piperesizeallowed, 0, "Pipe resizing allowed");
 225
 226 static void pipeinit(void *dummy __unused);
 227 static void pipeclose(struct pipe *cpipe);
 228 static void pipe_free_kmem(struct pipe *cpipe);
 229 static void pipe_create(struct pipe *pipe, int backing);
 230 static void pipe_paircreate(struct thread *td, struct pipepair **p_pp);
 231 static __inline int pipelock(struct pipe *cpipe, int catch);
 232 static __inline void pipeunlock(struct pipe *cpipe);
 233 #ifndef PIPE_NODIRECT
 234 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio);
 235 static void pipe_destroy_write_buffer(struct pipe *wpipe);
 236 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio);
 237 static void pipe_clone_write_buffer(struct pipe *wpipe);
 238 #endif
 239 static int pipespace(struct pipe *cpipe, int size);
 240 static int pipespace_new(struct pipe *cpipe, int size);
 241
 242 static int      pipe_zone_ctor(void *mem, int size, void *arg, int flags);
 243 static int      pipe_zone_init(void *mem, int size, int flags);
 244 static void     pipe_zone_fini(void *mem, int size);
 245
 246 static uma_zone_t pipe_zone;
 247 static struct unrhdr64 pipeino_unr;
 248 static dev_t pipedev_ino;
 249
 250 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
 251
 252 static void
 253 pipeinit(void *dummy __unused)
 254 {
 255
 256         pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair),
 257             pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini,
 258             UMA_ALIGN_PTR, 0);
 259         KASSERT(pipe_zone != NULL, ("pipe_zone not initialized"));
 260         new_unrhdr64(&pipeino_unr, 1);
 261         pipedev_ino = devfs_alloc_cdp_inode();
 262         KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized"));
 263 }
 264
 265 static int
 266 pipe_zone_ctor(void *mem, int size, void *arg, int flags)
 267 {
 268         struct pipepair *pp;
 269         struct pipe *rpipe, *wpipe;
 270
 271         KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size"));
 272
 273         pp = (struct pipepair *)mem;
 274
 275         /*
 276          * We zero both pipe endpoints to make sure all the kmem pointers
 277          * are NULL, flag fields are zero'd, etc.  We timestamp both
 278          * endpoints with the same time.
 279          */
 280         rpipe = &pp->pp_rpipe;
 281         bzero(rpipe, sizeof(*rpipe));
 282         vfs_timestamp(&rpipe->pipe_ctime);
 283         rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime;
 284
 285         wpipe = &pp->pp_wpipe;
 286         bzero(wpipe, sizeof(*wpipe));
 287         wpipe->pipe_ctime = rpipe->pipe_ctime;
 288         wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime;
 289
 290         rpipe->pipe_peer = wpipe;
 291         rpipe->pipe_pair = pp;
 292         wpipe->pipe_peer = rpipe;
 293         wpipe->pipe_pair = pp;
 294
 295         /*
 296          * Mark both endpoints as present; they will later get free'd
 297          * one at a time.  When both are free'd, then the whole pair
 298          * is released.
 299          */
 300         rpipe->pipe_present = PIPE_ACTIVE;
 301         wpipe->pipe_present = PIPE_ACTIVE;
 302
 303         /*
 304          * Eventually, the MAC Framework may initialize the label
 305          * in ctor or init, but for now we do it elswhere to avoid
 306          * blocking in ctor or init.
 307          */
 308         pp->pp_label = NULL;
 309
 310         return (0);
 311 }
 312
 313 static int
 314 pipe_zone_init(void *mem, int size, int flags)
 315 {
 316         struct pipepair *pp;
 317
 318         KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size"));
 319
 320         pp = (struct pipepair *)mem;
 321
 322         mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_NEW);
 323         return (0);
 324 }
 325
 326 static void
 327 pipe_zone_fini(void *mem, int size)
 328 {
 329         struct pipepair *pp;
 330
 331         KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size"));
 332
 333         pp = (struct pipepair *)mem;
 334
 335         mtx_destroy(&pp->pp_mtx);
 336 }
 337
 338 static void
 339 pipe_paircreate(struct thread *td, struct pipepair **p_pp)
 340 {
 341         struct pipepair *pp;
 342         struct pipe *rpipe, *wpipe;
 343
 344         *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK);
 345 #ifdef MAC
 346         /*
 347          * The MAC label is shared between the connected endpoints.  As a
 348          * result mac_pipe_init() and mac_pipe_create() are called once
 349          * for the pair, and not on the endpoints.
 350          */
 351         mac_pipe_init(pp);
 352         mac_pipe_create(td->td_ucred, pp);
 353 #endif
 354         rpipe = &pp->pp_rpipe;
 355         wpipe = &pp->pp_wpipe;
 356
 357         knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe));
 358         knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe));
 359
 360         /* Only the forward direction pipe is backed by default */
 361         pipe_create(rpipe, 1);
 362         pipe_create(wpipe, 0);
 363
 364         rpipe->pipe_state |= PIPE_DIRECTOK;
 365         wpipe->pipe_state |= PIPE_DIRECTOK;
 366 }
 367
 368 void
 369 pipe_named_ctor(struct pipe **ppipe, struct thread *td)
 370 {
 371         struct pipepair *pp;
 372
 373         pipe_paircreate(td, &pp);
 374         pp->pp_rpipe.pipe_state |= PIPE_NAMED;
 375         *ppipe = &pp->pp_rpipe;
 376 }
 377
 378 void
 379 pipe_dtor(struct pipe *dpipe)
 380 {
 381         struct pipe *peer;
 382
 383         peer = (dpipe->pipe_state & PIPE_NAMED) != 0 ? dpipe->pipe_peer : NULL;
 384         funsetown(&dpipe->pipe_sigio);
 385         pipeclose(dpipe);
 386         if (peer != NULL) {
 387                 funsetown(&peer->pipe_sigio);
 388                 pipeclose(peer);
 389         }
 390 }
 391
 392 /*
 393  * The pipe system call for the DTYPE_PIPE type of pipes.  If we fail, let
 394  * the zone pick up the pieces via pipeclose().
 395  */
 396 int
 397 kern_pipe(struct thread *td, int fildes[2], int flags, struct filecaps *fcaps1,
 398     struct filecaps *fcaps2)
 399 {
 400         struct file *rf, *wf;
 401         struct pipe *rpipe, *wpipe;
 402         struct pipepair *pp;
 403         int fd, fflags, error;
 404
 405         pipe_paircreate(td, &pp);
 406         rpipe = &pp->pp_rpipe;
 407         wpipe = &pp->pp_wpipe;
 408         error = falloc_caps(td, &rf, &fd, flags, fcaps1);
 409         if (error) {
 410                 pipeclose(rpipe);
 411                 pipeclose(wpipe);
 412                 return (error);
 413         }
 414         /* An extra reference on `rf' has been held for us by falloc_caps(). */
 415         fildes[0] = fd;
 416
 417         fflags = FREAD | FWRITE;
 418         if ((flags & O_NONBLOCK) != 0)
 419                 fflags |= FNONBLOCK;
 420
 421         /*
 422          * Warning: once we've gotten past allocation of the fd for the
 423          * read-side, we can only drop the read side via fdrop() in order
 424          * to avoid races against processes which manage to dup() the read
 425          * side while we are blocked trying to allocate the write side.
 426          */
 427         finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops);
 428         error = falloc_caps(td, &wf, &fd, flags, fcaps2);
 429         if (error) {
 430                 fdclose(td, rf, fildes[0]);
 431                 fdrop(rf, td);
 432                 /* rpipe has been closed by fdrop(). */
 433                 pipeclose(wpipe);
 434                 return (error);
 435         }
 436         /* An extra reference on `wf' has been held for us by falloc_caps(). */
 437         finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops);
 438         fdrop(wf, td);
 439         fildes[1] = fd;
 440         fdrop(rf, td);
 441
 442         return (0);
 443 }
 444
 445 #ifdef COMPAT_FREEBSD10
 446 /* ARGSUSED */
 447 int
 448 freebsd10_pipe(struct thread *td, struct freebsd10_pipe_args *uap __unused)
 449 {
 450         int error;
 451         int fildes[2];
 452
 453         error = kern_pipe(td, fildes, 0, NULL, NULL);
 454         if (error)
 455                 return (error);
 456
 457         td->td_retval[0] = fildes[0];
 458         td->td_retval[1] = fildes[1];
 459
 460         return (0);
 461 }
 462 #endif
 463
 464 int
 465 sys_pipe2(struct thread *td, struct pipe2_args *uap)
 466 {
 467         int error, fildes[2];
 468
 469         if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK))
 470                 return (EINVAL);
 471         error = kern_pipe(td, fildes, uap->flags, NULL, NULL);
 472         if (error)
 473                 return (error);
 474         error = copyout(fildes, uap->fildes, 2 * sizeof(int));
 475         if (error) {
 476                 (void)kern_close(td, fildes[0]);
 477                 (void)kern_close(td, fildes[1]);
 478         }
 479         return (error);
 480 }
 481
 482 /*
 483  * Allocate kva for pipe circular buffer, the space is pageable
 484  * This routine will 'realloc' the size of a pipe safely, if it fails
 485  * it will retain the old buffer.
 486  * If it fails it will return ENOMEM.
 487  */
 488 static int
 489 pipespace_new(struct pipe *cpipe, 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, (vm_offset_t *)&buffer, size, 0,
 508             VMFS_ANY_SPACE, VM_PROT_RW, VM_PROT_RW, 0);
 509         if (error != KERN_SUCCESS) {
 510                 if ((cpipe->pipe_buffer.buffer == NULL) &&
 511                         (size > SMALL_PIPE_SIZE)) {
 512                         size = SMALL_PIPE_SIZE;
 513                         pipefragretry++;
 514                         goto retry;
 515                 }
 516                 if (cpipe->pipe_buffer.buffer == NULL) {
 517                         pipeallocfail++;
 518                         if (ppsratecheck(&lastfail, &curfail, 1))
 519                                 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n");
 520                 } else {
 521                         piperesizefail++;
 522                 }
 523                 return (ENOMEM);
 524         }
 525
 526         /* copy data, then free old resources if we're resizing */
 527         if (cnt > 0) {
 528                 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) {
 529                         firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out;
 530                         bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
 531                                 buffer, firstseg);
 532                         if ((cnt - firstseg) > 0)
 533                                 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg],
 534                                         cpipe->pipe_buffer.in);
 535                 } else {
 536                         bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
 537                                 buffer, cnt);
 538                 }
 539         }
 540         pipe_free_kmem(cpipe);
 541         cpipe->pipe_buffer.buffer = buffer;
 542         cpipe->pipe_buffer.size = size;
 543         cpipe->pipe_buffer.in = cnt;
 544         cpipe->pipe_buffer.out = 0;
 545         cpipe->pipe_buffer.cnt = cnt;
 546         atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size);
 547         return (0);
 548 }
 549
 550 /*
 551  * Wrapper for pipespace_new() that performs locking assertions.
 552  */
 553 static int
 554 pipespace(struct pipe *cpipe, int size)
 555 {
 556
 557         KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
 558                 ("Unlocked pipe passed to pipespace"));
 559         return (pipespace_new(cpipe, size));
 560 }
 561
 562 /*
 563  * lock a pipe for I/O, blocking other access
 564  */
 565 static __inline int
 566 pipelock(struct pipe *cpipe, int catch)
 567 {
 568         int error;
 569
 570         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 571         while (cpipe->pipe_state & PIPE_LOCKFL) {
 572                 cpipe->pipe_state |= PIPE_LWANT;
 573                 error = msleep(cpipe, PIPE_MTX(cpipe),
 574                     catch ? (PRIBIO | PCATCH) : PRIBIO,
 575                     "pipelk", 0);
 576                 if (error != 0)
 577                         return (error);
 578         }
 579         cpipe->pipe_state |= PIPE_LOCKFL;
 580         return (0);
 581 }
 582
 583 /*
 584  * unlock a pipe I/O lock
 585  */
 586 static __inline void
 587 pipeunlock(struct pipe *cpipe)
 588 {
 589
 590         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 591         KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
 592                 ("Unlocked pipe passed to pipeunlock"));
 593         cpipe->pipe_state &= ~PIPE_LOCKFL;
 594         if (cpipe->pipe_state & PIPE_LWANT) {
 595                 cpipe->pipe_state &= ~PIPE_LWANT;
 596                 wakeup(cpipe);
 597         }
 598 }
 599
 600 void
 601 pipeselwakeup(struct pipe *cpipe)
 602 {
 603
 604         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 605         if (cpipe->pipe_state & PIPE_SEL) {
 606                 selwakeuppri(&cpipe->pipe_sel, PSOCK);
 607                 if (!SEL_WAITING(&cpipe->pipe_sel))
 608                         cpipe->pipe_state &= ~PIPE_SEL;
 609         }
 610         if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
 611                 pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
 612         KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0);
 613 }
 614
 615 /*
 616  * Initialize and allocate VM and memory for pipe.  The structure
 617  * will start out zero'd from the ctor, so we just manage the kmem.
 618  */
 619 static void
 620 pipe_create(struct pipe *pipe, int backing)
 621 {
 622
 623         if (backing) {
 624                 /*
 625                  * Note that these functions can fail if pipe map is exhausted
 626                  * (as a result of too many pipes created), but we ignore the
 627                  * error as it is not fatal and could be provoked by
 628                  * unprivileged users. The only consequence is worse performance
 629                  * with given pipe.
 630                  */
 631                 if (amountpipekva > maxpipekva / 2)
 632                         (void)pipespace_new(pipe, SMALL_PIPE_SIZE);
 633                 else
 634                         (void)pipespace_new(pipe, PIPE_SIZE);
 635         }
 636
 637         pipe->pipe_ino = alloc_unr64(&pipeino_unr);
 638 }
 639
 640 /* ARGSUSED */
 641 static int
 642 pipe_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
 643     int flags, struct thread *td)
 644 {
 645         struct pipe *rpipe;
 646         int error;
 647         int nread = 0;
 648         int size;
 649
 650         rpipe = fp->f_data;
 651         PIPE_LOCK(rpipe);
 652         ++rpipe->pipe_busy;
 653         error = pipelock(rpipe, 1);
 654         if (error)
 655                 goto unlocked_error;
 656
 657 #ifdef MAC
 658         error = mac_pipe_check_read(active_cred, rpipe->pipe_pair);
 659         if (error)
 660                 goto locked_error;
 661 #endif
 662         if (amountpipekva > (3 * maxpipekva) / 4) {
 663                 if (!(rpipe->pipe_state & PIPE_DIRECTW) &&
 664                         (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
 665                         (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
 666                         (piperesizeallowed == 1)) {
 667                         PIPE_UNLOCK(rpipe);
 668                         pipespace(rpipe, SMALL_PIPE_SIZE);
 669                         PIPE_LOCK(rpipe);
 670                 }
 671         }
 672
 673         while (uio->uio_resid) {
 674                 /*
 675                  * normal pipe buffer receive
 676                  */
 677                 if (rpipe->pipe_buffer.cnt > 0) {
 678                         size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
 679                         if (size > rpipe->pipe_buffer.cnt)
 680                                 size = rpipe->pipe_buffer.cnt;
 681                         if (size > uio->uio_resid)
 682                                 size = uio->uio_resid;
 683
 684                         PIPE_UNLOCK(rpipe);
 685                         error = uiomove(
 686                             &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
 687                             size, uio);
 688                         PIPE_LOCK(rpipe);
 689                         if (error)
 690                                 break;
 691
 692                         rpipe->pipe_buffer.out += size;
 693                         if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
 694                                 rpipe->pipe_buffer.out = 0;
 695
 696                         rpipe->pipe_buffer.cnt -= size;
 697
 698                         /*
 699                          * If there is no more to read in the pipe, reset
 700                          * its pointers to the beginning.  This improves
 701                          * cache hit stats.
 702                          */
 703                         if (rpipe->pipe_buffer.cnt == 0) {
 704                                 rpipe->pipe_buffer.in = 0;
 705                                 rpipe->pipe_buffer.out = 0;
 706                         }
 707                         nread += size;
 708 #ifndef PIPE_NODIRECT
 709                 /*
 710                  * Direct copy, bypassing a kernel buffer.
 711                  */
 712                 } else if ((size = rpipe->pipe_map.cnt) &&
 713                            (rpipe->pipe_state & PIPE_DIRECTW)) {
 714                         if (size > uio->uio_resid)
 715                                 size = (u_int) uio->uio_resid;
 716
 717                         PIPE_UNLOCK(rpipe);
 718                         error = uiomove_fromphys(rpipe->pipe_map.ms,
 719                             rpipe->pipe_map.pos, size, uio);
 720                         PIPE_LOCK(rpipe);
 721                         if (error)
 722                                 break;
 723                         nread += size;
 724                         rpipe->pipe_map.pos += size;
 725                         rpipe->pipe_map.cnt -= size;
 726                         if (rpipe->pipe_map.cnt == 0) {
 727                                 rpipe->pipe_state &= ~(PIPE_DIRECTW|PIPE_WANTW);
 728                                 wakeup(rpipe);
 729                         }
 730 #endif
 731                 } else {
 732                         /*
 733                          * detect EOF condition
 734                          * read returns 0 on EOF, no need to set error
 735                          */
 736                         if (rpipe->pipe_state & PIPE_EOF)
 737                                 break;
 738
 739                         /*
 740                          * If the "write-side" has been blocked, wake it up now.
 741                          */
 742                         if (rpipe->pipe_state & PIPE_WANTW) {
 743                                 rpipe->pipe_state &= ~PIPE_WANTW;
 744                                 wakeup(rpipe);
 745                         }
 746
 747                         /*
 748                          * Break if some data was read.
 749                          */
 750                         if (nread > 0)
 751                                 break;
 752
 753                         /*
 754                          * Unlock the pipe buffer for our remaining processing.
 755                          * We will either break out with an error or we will
 756                          * sleep and relock to loop.
 757                          */
 758                         pipeunlock(rpipe);
 759
 760                         /*
 761                          * Handle non-blocking mode operation or
 762                          * wait for more data.
 763                          */
 764                         if (fp->f_flag & FNONBLOCK) {
 765                                 error = EAGAIN;
 766                         } else {
 767                                 rpipe->pipe_state |= PIPE_WANTR;
 768                                 if ((error = msleep(rpipe, PIPE_MTX(rpipe),
 769                                     PRIBIO | PCATCH,
 770                                     "piperd", 0)) == 0)
 771                                         error = pipelock(rpipe, 1);
 772                         }
 773                         if (error)
 774                                 goto unlocked_error;
 775                 }
 776         }
 777 #ifdef MAC
 778 locked_error:
 779 #endif
 780         pipeunlock(rpipe);
 781
 782         /* XXX: should probably do this before getting any locks. */
 783         if (error == 0)
 784                 vfs_timestamp(&rpipe->pipe_atime);
 785 unlocked_error:
 786         --rpipe->pipe_busy;
 787
 788         /*
 789          * PIPE_WANT processing only makes sense if pipe_busy is 0.
 790          */
 791         if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
 792                 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
 793                 wakeup(rpipe);
 794         } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
 795                 /*
 796                  * Handle write blocking hysteresis.
 797                  */
 798                 if (rpipe->pipe_state & PIPE_WANTW) {
 799                         rpipe->pipe_state &= ~PIPE_WANTW;
 800                         wakeup(rpipe);
 801                 }
 802         }
 803
 804         if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
 805                 pipeselwakeup(rpipe);
 806
 807         PIPE_UNLOCK(rpipe);
 808         return (error);
 809 }
 810
 811 #ifndef PIPE_NODIRECT
 812 /*
 813  * Map the sending processes' buffer into kernel space and wire it.
 814  * This is similar to a physical write operation.
 815  */
 816 static int
 817 pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio)
 818 {
 819         u_int size;
 820         int i;
 821
 822         PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED);
 823         KASSERT(wpipe->pipe_state & PIPE_DIRECTW,
 824                 ("Clone attempt on non-direct write pipe!"));
 825
 826         if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size)
 827                 size = wpipe->pipe_buffer.size;
 828         else
 829                 size = uio->uio_iov->iov_len;
 830
 831         if ((i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
 832             (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ,
 833             wpipe->pipe_map.ms, PIPENPAGES)) < 0)
 834                 return (EFAULT);
 835
 836 /*
 837  * set up the control block
 838  */
 839         wpipe->pipe_map.npages = i;
 840         wpipe->pipe_map.pos =
 841             ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK;
 842         wpipe->pipe_map.cnt = size;
 843
 844 /*
 845  * and update the uio data
 846  */
 847
 848         uio->uio_iov->iov_len -= size;
 849         uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size;
 850         if (uio->uio_iov->iov_len == 0)
 851                 uio->uio_iov++;
 852         uio->uio_resid -= size;
 853         uio->uio_offset += size;
 854         return (0);
 855 }
 856
 857 /*
 858  * unmap and unwire the process buffer
 859  */
 860 static void
 861 pipe_destroy_write_buffer(struct pipe *wpipe)
 862 {
 863
 864         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 865         vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages);
 866         wpipe->pipe_map.npages = 0;
 867 }
 868
 869 /*
 870  * In the case of a signal, the writing process might go away.  This
 871  * code copies the data into the circular buffer so that the source
 872  * pages can be freed without loss of data.
 873  */
 874 static void
 875 pipe_clone_write_buffer(struct pipe *wpipe)
 876 {
 877         struct uio uio;
 878         struct iovec iov;
 879         int size;
 880         int pos;
 881
 882         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 883         size = wpipe->pipe_map.cnt;
 884         pos = wpipe->pipe_map.pos;
 885
 886         wpipe->pipe_buffer.in = size;
 887         wpipe->pipe_buffer.out = 0;
 888         wpipe->pipe_buffer.cnt = size;
 889         wpipe->pipe_state &= ~PIPE_DIRECTW;
 890
 891         PIPE_UNLOCK(wpipe);
 892         iov.iov_base = wpipe->pipe_buffer.buffer;
 893         iov.iov_len = size;
 894         uio.uio_iov = &iov;
 895         uio.uio_iovcnt = 1;
 896         uio.uio_offset = 0;
 897         uio.uio_resid = size;
 898         uio.uio_segflg = UIO_SYSSPACE;
 899         uio.uio_rw = UIO_READ;
 900         uio.uio_td = curthread;
 901         uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio);
 902         PIPE_LOCK(wpipe);
 903         pipe_destroy_write_buffer(wpipe);
 904 }
 905
 906 /*
 907  * This implements the pipe buffer write mechanism.  Note that only
 908  * a direct write OR a normal pipe write can be pending at any given time.
 909  * If there are any characters in the pipe buffer, the direct write will
 910  * be deferred until the receiving process grabs all of the bytes from
 911  * the pipe buffer.  Then the direct mapping write is set-up.
 912  */
 913 static int
 914 pipe_direct_write(struct pipe *wpipe, struct uio *uio)
 915 {
 916         int error;
 917
 918 retry:
 919         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 920         error = pipelock(wpipe, 1);
 921         if (error != 0)
 922                 goto error1;
 923         if ((wpipe->pipe_state & PIPE_EOF) != 0) {
 924                 error = EPIPE;
 925                 pipeunlock(wpipe);
 926                 goto error1;
 927         }
 928         while (wpipe->pipe_state & PIPE_DIRECTW) {
 929                 if (wpipe->pipe_state & PIPE_WANTR) {
 930                         wpipe->pipe_state &= ~PIPE_WANTR;
 931                         wakeup(wpipe);
 932                 }
 933                 pipeselwakeup(wpipe);
 934                 wpipe->pipe_state |= PIPE_WANTW;
 935                 pipeunlock(wpipe);
 936                 error = msleep(wpipe, PIPE_MTX(wpipe),
 937                     PRIBIO | PCATCH, "pipdww", 0);
 938                 if (error)
 939                         goto error1;
 940                 else
 941                         goto retry;
 942         }
 943         wpipe->pipe_map.cnt = 0;        /* transfer not ready yet */
 944         if (wpipe->pipe_buffer.cnt > 0) {
 945                 if (wpipe->pipe_state & PIPE_WANTR) {
 946                         wpipe->pipe_state &= ~PIPE_WANTR;
 947                         wakeup(wpipe);
 948                 }
 949                 pipeselwakeup(wpipe);
 950                 wpipe->pipe_state |= PIPE_WANTW;
 951                 pipeunlock(wpipe);
 952                 error = msleep(wpipe, PIPE_MTX(wpipe),
 953                     PRIBIO | PCATCH, "pipdwc", 0);
 954                 if (error)
 955                         goto error1;
 956                 else
 957                         goto retry;
 958         }
 959
 960         wpipe->pipe_state |= PIPE_DIRECTW;
 961
 962         PIPE_UNLOCK(wpipe);
 963         error = pipe_build_write_buffer(wpipe, uio);
 964         PIPE_LOCK(wpipe);
 965         if (error) {
 966                 wpipe->pipe_state &= ~PIPE_DIRECTW;
 967                 pipeunlock(wpipe);
 968                 goto error1;
 969         }
 970
 971         error = 0;
 972         while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
 973                 if (wpipe->pipe_state & PIPE_EOF) {
 974                         pipe_destroy_write_buffer(wpipe);
 975                         pipeselwakeup(wpipe);
 976                         pipeunlock(wpipe);
 977                         error = EPIPE;
 978                         goto error1;
 979                 }
 980                 if (wpipe->pipe_state & PIPE_WANTR) {
 981                         wpipe->pipe_state &= ~PIPE_WANTR;
 982                         wakeup(wpipe);
 983                 }
 984                 pipeselwakeup(wpipe);
 985                 wpipe->pipe_state |= PIPE_WANTW;
 986                 pipeunlock(wpipe);
 987                 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
 988                     "pipdwt", 0);
 989                 pipelock(wpipe, 0);
 990         }
 991
 992         if (wpipe->pipe_state & PIPE_EOF)
 993                 error = EPIPE;
 994         if (wpipe->pipe_state & PIPE_DIRECTW) {
 995                 /*
 996                  * this bit of trickery substitutes a kernel buffer for
 997                  * the process that might be going away.
 998                  */
 999                 pipe_clone_write_buffer(wpipe);
1000         } else {
1001                 pipe_destroy_write_buffer(wpipe);
1002         }
1003         pipeunlock(wpipe);
1004         return (error);
1005
1006 error1:
1007         wakeup(wpipe);
1008         return (error);
1009 }
1010 #endif
1011
1012 static int
1013 pipe_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
1014     int flags, struct thread *td)
1015 {
1016         int error = 0;
1017         int desiredsize;
1018         ssize_t orig_resid;
1019         struct pipe *wpipe, *rpipe;
1020
1021         rpipe = fp->f_data;
1022         wpipe = PIPE_PEER(rpipe);
1023         PIPE_LOCK(rpipe);
1024         error = pipelock(wpipe, 1);
1025         if (error) {
1026                 PIPE_UNLOCK(rpipe);
1027                 return (error);
1028         }
1029         /*
1030          * detect loss of pipe read side, issue SIGPIPE if lost.
1031          */
1032         if (wpipe->pipe_present != PIPE_ACTIVE ||
1033             (wpipe->pipe_state & PIPE_EOF)) {
1034                 pipeunlock(wpipe);
1035                 PIPE_UNLOCK(rpipe);
1036                 return (EPIPE);
1037         }
1038 #ifdef MAC
1039         error = mac_pipe_check_write(active_cred, wpipe->pipe_pair);
1040         if (error) {
1041                 pipeunlock(wpipe);
1042                 PIPE_UNLOCK(rpipe);
1043                 return (error);
1044         }
1045 #endif
1046         ++wpipe->pipe_busy;
1047
1048         /* Choose a larger size if it's advantageous */
1049         desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size);
1050         while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) {
1051                 if (piperesizeallowed != 1)
1052                         break;
1053                 if (amountpipekva > maxpipekva / 2)
1054                         break;
1055                 if (desiredsize == BIG_PIPE_SIZE)
1056                         break;
1057                 desiredsize = desiredsize * 2;
1058         }
1059
1060         /* Choose a smaller size if we're in a OOM situation */
1061         if ((amountpipekva > (3 * maxpipekva) / 4) &&
1062                 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
1063                 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
1064                 (piperesizeallowed == 1))
1065                 desiredsize = SMALL_PIPE_SIZE;
1066
1067         /* Resize if the above determined that a new size was necessary */
1068         if ((desiredsize != wpipe->pipe_buffer.size) &&
1069                 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) {
1070                 PIPE_UNLOCK(wpipe);
1071                 pipespace(wpipe, desiredsize);
1072                 PIPE_LOCK(wpipe);
1073         }
1074         if (wpipe->pipe_buffer.size == 0) {
1075                 /*
1076                  * This can only happen for reverse direction use of pipes
1077                  * in a complete OOM situation.
1078                  */
1079                 error = ENOMEM;
1080                 --wpipe->pipe_busy;
1081                 pipeunlock(wpipe);
1082                 PIPE_UNLOCK(wpipe);
1083                 return (error);
1084         }
1085
1086         pipeunlock(wpipe);
1087
1088         orig_resid = uio->uio_resid;
1089
1090         while (uio->uio_resid) {
1091                 int space;
1092
1093                 pipelock(wpipe, 0);
1094                 if (wpipe->pipe_state & PIPE_EOF) {
1095                         pipeunlock(wpipe);
1096                         error = EPIPE;
1097                         break;
1098                 }
1099 #ifndef PIPE_NODIRECT
1100                 /*
1101                  * If the transfer is large, we can gain performance if
1102                  * we do process-to-process copies directly.
1103                  * If the write is non-blocking, we don't use the
1104                  * direct write mechanism.
1105                  *
1106                  * The direct write mechanism will detect the reader going
1107                  * away on us.
1108                  */
1109                 if (uio->uio_segflg == UIO_USERSPACE &&
1110                     uio->uio_iov->iov_len >= PIPE_MINDIRECT &&
1111                     wpipe->pipe_buffer.size >= PIPE_MINDIRECT &&
1112                     (fp->f_flag & FNONBLOCK) == 0) {
1113                         pipeunlock(wpipe);
1114                         error = pipe_direct_write(wpipe, uio);
1115                         if (error)
1116                                 break;
1117                         continue;
1118                 }
1119 #endif
1120
1121                 /*
1122                  * Pipe buffered writes cannot be coincidental with
1123                  * direct writes.  We wait until the currently executing
1124                  * direct write is completed before we start filling the
1125                  * pipe buffer.  We break out if a signal occurs or the
1126                  * reader goes away.
1127                  */
1128                 if (wpipe->pipe_state & PIPE_DIRECTW) {
1129                         if (wpipe->pipe_state & PIPE_WANTR) {
1130                                 wpipe->pipe_state &= ~PIPE_WANTR;
1131                                 wakeup(wpipe);
1132                         }
1133                         pipeselwakeup(wpipe);
1134                         wpipe->pipe_state |= PIPE_WANTW;
1135                         pipeunlock(wpipe);
1136                         error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH,
1137                             "pipbww", 0);
1138                         if (error)
1139                                 break;
1140                         else
1141                                 continue;
1142                 }
1143
1144                 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1145
1146                 /* Writes of size <= PIPE_BUF must be atomic. */
1147                 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
1148                         space = 0;
1149
1150                 if (space > 0) {
1151                         int size;       /* Transfer size */
1152                         int segsize;    /* first segment to transfer */
1153
1154                         /*
1155                          * Transfer size is minimum of uio transfer
1156                          * and free space in pipe buffer.
1157                          */
1158                         if (space > uio->uio_resid)
1159                                 size = uio->uio_resid;
1160                         else
1161                                 size = space;
1162                         /*
1163                          * First segment to transfer is minimum of
1164                          * transfer size and contiguous space in
1165                          * pipe buffer.  If first segment to transfer
1166                          * is less than the transfer size, we've got
1167                          * a wraparound in the buffer.
1168                          */
1169                         segsize = wpipe->pipe_buffer.size -
1170                                 wpipe->pipe_buffer.in;
1171                         if (segsize > size)
1172                                 segsize = size;
1173
1174                         /* Transfer first segment */
1175
1176                         PIPE_UNLOCK(rpipe);
1177                         error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
1178                                         segsize, uio);
1179                         PIPE_LOCK(rpipe);
1180
1181                         if (error == 0 && segsize < size) {
1182                                 KASSERT(wpipe->pipe_buffer.in + segsize ==
1183                                         wpipe->pipe_buffer.size,
1184                                         ("Pipe buffer wraparound disappeared"));
1185                                 /*
1186                                  * Transfer remaining part now, to
1187                                  * support atomic writes.  Wraparound
1188                                  * happened.
1189                                  */
1190
1191                                 PIPE_UNLOCK(rpipe);
1192                                 error = uiomove(
1193                                     &wpipe->pipe_buffer.buffer[0],
1194                                     size - segsize, uio);
1195                                 PIPE_LOCK(rpipe);
1196                         }
1197                         if (error == 0) {
1198                                 wpipe->pipe_buffer.in += size;
1199                                 if (wpipe->pipe_buffer.in >=
1200                                     wpipe->pipe_buffer.size) {
1201                                         KASSERT(wpipe->pipe_buffer.in ==
1202                                                 size - segsize +
1203                                                 wpipe->pipe_buffer.size,
1204                                                 ("Expected wraparound bad"));
1205                                         wpipe->pipe_buffer.in = size - segsize;
1206                                 }
1207
1208                                 wpipe->pipe_buffer.cnt += size;
1209                                 KASSERT(wpipe->pipe_buffer.cnt <=
1210                                         wpipe->pipe_buffer.size,
1211                                         ("Pipe buffer overflow"));
1212                         }
1213                         pipeunlock(wpipe);
1214                         if (error != 0)
1215                                 break;
1216                 } else {
1217                         /*
1218                          * If the "read-side" has been blocked, wake it up now.
1219                          */
1220                         if (wpipe->pipe_state & PIPE_WANTR) {
1221                                 wpipe->pipe_state &= ~PIPE_WANTR;
1222                                 wakeup(wpipe);
1223                         }
1224
1225                         /*
1226                          * don't block on non-blocking I/O
1227                          */
1228                         if (fp->f_flag & FNONBLOCK) {
1229                                 error = EAGAIN;
1230                                 pipeunlock(wpipe);
1231                                 break;
1232                         }
1233
1234                         /*
1235                          * We have no more space and have something to offer,
1236                          * wake up select/poll.
1237                          */
1238                         pipeselwakeup(wpipe);
1239
1240                         wpipe->pipe_state |= PIPE_WANTW;
1241                         pipeunlock(wpipe);
1242                         error = msleep(wpipe, PIPE_MTX(rpipe),
1243                             PRIBIO | PCATCH, "pipewr", 0);
1244                         if (error != 0)
1245                                 break;
1246                 }
1247         }
1248
1249         pipelock(wpipe, 0);
1250         --wpipe->pipe_busy;
1251
1252         if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1253                 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1254                 wakeup(wpipe);
1255         } else if (wpipe->pipe_buffer.cnt > 0) {
1256                 /*
1257                  * If we have put any characters in the buffer, we wake up
1258                  * the reader.
1259                  */
1260                 if (wpipe->pipe_state & PIPE_WANTR) {
1261                         wpipe->pipe_state &= ~PIPE_WANTR;
1262                         wakeup(wpipe);
1263                 }
1264         }
1265
1266         /*
1267          * Don't return EPIPE if any byte was written.
1268          * EINTR and other interrupts are handled by generic I/O layer.
1269          * Do not pretend that I/O succeeded for obvious user error
1270          * like EFAULT.
1271          */
1272         if (uio->uio_resid != orig_resid && error == EPIPE)
1273                 error = 0;
1274
1275         if (error == 0)
1276                 vfs_timestamp(&wpipe->pipe_mtime);
1277
1278         /*
1279          * We have something to offer,
1280          * wake up select/poll.
1281          */
1282         if (wpipe->pipe_buffer.cnt)
1283                 pipeselwakeup(wpipe);
1284
1285         pipeunlock(wpipe);
1286         PIPE_UNLOCK(rpipe);
1287         return (error);
1288 }
1289
1290 /* ARGSUSED */
1291 static int
1292 pipe_truncate(struct file *fp, off_t length, struct ucred *active_cred,
1293     struct thread *td)
1294 {
1295         struct pipe *cpipe;
1296         int error;
1297
1298         cpipe = fp->f_data;
1299         if (cpipe->pipe_state & PIPE_NAMED)
1300                 error = vnops.fo_truncate(fp, length, active_cred, td);
1301         else
1302                 error = invfo_truncate(fp, length, active_cred, td);
1303         return (error);
1304 }
1305
1306 /*
1307  * we implement a very minimal set of ioctls for compatibility with sockets.
1308  */
1309 static int
1310 pipe_ioctl(struct file *fp, u_long cmd, void *data, struct ucred *active_cred,
1311     struct thread *td)
1312 {
1313         struct pipe *mpipe = fp->f_data;
1314         int error;
1315
1316         PIPE_LOCK(mpipe);
1317
1318 #ifdef MAC
1319         error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data);
1320         if (error) {
1321                 PIPE_UNLOCK(mpipe);
1322                 return (error);
1323         }
1324 #endif
1325
1326         error = 0;
1327         switch (cmd) {
1328
1329         case FIONBIO:
1330                 break;
1331
1332         case FIOASYNC:
1333                 if (*(int *)data) {
1334                         mpipe->pipe_state |= PIPE_ASYNC;
1335                 } else {
1336                         mpipe->pipe_state &= ~PIPE_ASYNC;
1337                 }
1338                 break;
1339
1340         case FIONREAD:
1341                 if (!(fp->f_flag & FREAD)) {
1342                         *(int *)data = 0;
1343                         PIPE_UNLOCK(mpipe);
1344                         return (0);
1345                 }
1346                 if (mpipe->pipe_state & PIPE_DIRECTW)
1347                         *(int *)data = mpipe->pipe_map.cnt;
1348                 else
1349                         *(int *)data = mpipe->pipe_buffer.cnt;
1350                 break;
1351
1352         case FIOSETOWN:
1353                 PIPE_UNLOCK(mpipe);
1354                 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
1355                 goto out_unlocked;
1356
1357         case FIOGETOWN:
1358                 *(int *)data = fgetown(&mpipe->pipe_sigio);
1359                 break;
1360
1361         /* This is deprecated, FIOSETOWN should be used instead. */
1362         case TIOCSPGRP:
1363                 PIPE_UNLOCK(mpipe);
1364                 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
1365                 goto out_unlocked;
1366
1367         /* This is deprecated, FIOGETOWN should be used instead. */
1368         case TIOCGPGRP:
1369                 *(int *)data = -fgetown(&mpipe->pipe_sigio);
1370                 break;
1371
1372         default:
1373                 error = ENOTTY;
1374                 break;
1375         }
1376         PIPE_UNLOCK(mpipe);
1377 out_unlocked:
1378         return (error);
1379 }
1380
1381 static int
1382 pipe_poll(struct file *fp, int events, struct ucred *active_cred,
1383     struct thread *td)
1384 {
1385         struct pipe *rpipe;
1386         struct pipe *wpipe;
1387         int levents, revents;
1388 #ifdef MAC
1389         int error;
1390 #endif
1391
1392         revents = 0;
1393         rpipe = fp->f_data;
1394         wpipe = PIPE_PEER(rpipe);
1395         PIPE_LOCK(rpipe);
1396 #ifdef MAC
1397         error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair);
1398         if (error)
1399                 goto locked_error;
1400 #endif
1401         if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM))
1402                 if ((rpipe->pipe_state & PIPE_DIRECTW) ||
1403                     (rpipe->pipe_buffer.cnt > 0))
1404                         revents |= events & (POLLIN | POLLRDNORM);
1405
1406         if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM))
1407                 if (wpipe->pipe_present != PIPE_ACTIVE ||
1408                     (wpipe->pipe_state & PIPE_EOF) ||
1409                     (((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
1410                      ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF ||
1411                          wpipe->pipe_buffer.size == 0)))
1412                         revents |= events & (POLLOUT | POLLWRNORM);
1413
1414         levents = events &
1415             (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND);
1416         if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents &&
1417             fp->f_seqcount == rpipe->pipe_wgen)
1418                 events |= POLLINIGNEOF;
1419
1420         if ((events & POLLINIGNEOF) == 0) {
1421                 if (rpipe->pipe_state & PIPE_EOF) {
1422                         revents |= (events & (POLLIN | POLLRDNORM));
1423                         if (wpipe->pipe_present != PIPE_ACTIVE ||
1424                             (wpipe->pipe_state & PIPE_EOF))
1425                                 revents |= POLLHUP;
1426                 }
1427         }
1428
1429         if (revents == 0) {
1430                 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) {
1431                         selrecord(td, &rpipe->pipe_sel);
1432                         if (SEL_WAITING(&rpipe->pipe_sel))
1433                                 rpipe->pipe_state |= PIPE_SEL;
1434                 }
1435
1436                 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) {
1437                         selrecord(td, &wpipe->pipe_sel);
1438                         if (SEL_WAITING(&wpipe->pipe_sel))
1439                                 wpipe->pipe_state |= PIPE_SEL;
1440                 }
1441         }
1442 #ifdef MAC
1443 locked_error:
1444 #endif
1445         PIPE_UNLOCK(rpipe);
1446
1447         return (revents);
1448 }
1449
1450 /*
1451  * We shouldn't need locks here as we're doing a read and this should
1452  * be a natural race.
1453  */
1454 static int
1455 pipe_stat(struct file *fp, struct stat *ub, struct ucred *active_cred,
1456     struct thread *td)
1457 {
1458         struct pipe *pipe;
1459 #ifdef MAC
1460         int error;
1461 #endif
1462
1463         pipe = fp->f_data;
1464         PIPE_LOCK(pipe);
1465 #ifdef MAC
1466         error = mac_pipe_check_stat(active_cred, pipe->pipe_pair);
1467         if (error) {
1468                 PIPE_UNLOCK(pipe);
1469                 return (error);
1470         }
1471 #endif
1472
1473         /* For named pipes ask the underlying filesystem. */
1474         if (pipe->pipe_state & PIPE_NAMED) {
1475                 PIPE_UNLOCK(pipe);
1476                 return (vnops.fo_stat(fp, ub, active_cred, td));
1477         }
1478
1479         PIPE_UNLOCK(pipe);
1480
1481         bzero(ub, sizeof(*ub));
1482         ub->st_mode = S_IFIFO;
1483         ub->st_blksize = PAGE_SIZE;
1484         if (pipe->pipe_state & PIPE_DIRECTW)
1485                 ub->st_size = pipe->pipe_map.cnt;
1486         else
1487                 ub->st_size = pipe->pipe_buffer.cnt;
1488         ub->st_blocks = howmany(ub->st_size, ub->st_blksize);
1489         ub->st_atim = pipe->pipe_atime;
1490         ub->st_mtim = pipe->pipe_mtime;
1491         ub->st_ctim = pipe->pipe_ctime;
1492         ub->st_uid = fp->f_cred->cr_uid;
1493         ub->st_gid = fp->f_cred->cr_gid;
1494         ub->st_dev = pipedev_ino;
1495         ub->st_ino = pipe->pipe_ino;
1496         /*
1497          * Left as 0: st_nlink, st_rdev, st_flags, st_gen.
1498          */
1499         return (0);
1500 }
1501
1502 /* ARGSUSED */
1503 static int
1504 pipe_close(struct file *fp, struct thread *td)
1505 {
1506
1507         if (fp->f_vnode != NULL)
1508                 return vnops.fo_close(fp, td);
1509         fp->f_ops = &badfileops;
1510         pipe_dtor(fp->f_data);
1511         fp->f_data = NULL;
1512         return (0);
1513 }
1514
1515 static int
1516 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td)
1517 {
1518         struct pipe *cpipe;
1519         int error;
1520
1521         cpipe = fp->f_data;
1522         if (cpipe->pipe_state & PIPE_NAMED)
1523                 error = vn_chmod(fp, mode, active_cred, td);
1524         else
1525                 error = invfo_chmod(fp, mode, active_cred, td);
1526         return (error);
1527 }
1528
1529 static int
1530 pipe_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
1531     struct thread *td)
1532 {
1533         struct pipe *cpipe;
1534         int error;
1535
1536         cpipe = fp->f_data;
1537         if (cpipe->pipe_state & PIPE_NAMED)
1538                 error = vn_chown(fp, uid, gid, active_cred, td);
1539         else
1540                 error = invfo_chown(fp, uid, gid, active_cred, td);
1541         return (error);
1542 }
1543
1544 static int
1545 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
1546 {
1547         struct pipe *pi;
1548
1549         if (fp->f_type == DTYPE_FIFO)
1550                 return (vn_fill_kinfo(fp, kif, fdp));
1551         kif->kf_type = KF_TYPE_PIPE;
1552         pi = fp->f_data;
1553         kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi;
1554         kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer;
1555         kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt;
1556         return (0);
1557 }
1558
1559 static void
1560 pipe_free_kmem(struct pipe *cpipe)
1561 {
1562
1563         KASSERT(!mtx_owned(PIPE_MTX(cpipe)),
1564             ("pipe_free_kmem: pipe mutex locked"));
1565
1566         if (cpipe->pipe_buffer.buffer != NULL) {
1567                 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size);
1568                 vm_map_remove(pipe_map,
1569                     (vm_offset_t)cpipe->pipe_buffer.buffer,
1570                     (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size);
1571                 cpipe->pipe_buffer.buffer = NULL;
1572         }
1573 #ifndef PIPE_NODIRECT
1574         {
1575                 cpipe->pipe_map.cnt = 0;
1576                 cpipe->pipe_map.pos = 0;
1577                 cpipe->pipe_map.npages = 0;
1578         }
1579 #endif
1580 }
1581
1582 /*
1583  * shutdown the pipe
1584  */
1585 static void
1586 pipeclose(struct pipe *cpipe)
1587 {
1588         struct pipepair *pp;
1589         struct pipe *ppipe;
1590
1591         KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL"));
1592
1593         PIPE_LOCK(cpipe);
1594         pipelock(cpipe, 0);
1595         pp = cpipe->pipe_pair;
1596
1597         pipeselwakeup(cpipe);
1598
1599         /*
1600          * If the other side is blocked, wake it up saying that
1601          * we want to close it down.
1602          */
1603         cpipe->pipe_state |= PIPE_EOF;
1604         while (cpipe->pipe_busy) {
1605                 wakeup(cpipe);
1606                 cpipe->pipe_state |= PIPE_WANT;
1607                 pipeunlock(cpipe);
1608                 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
1609                 pipelock(cpipe, 0);
1610         }
1611
1612
1613         /*
1614          * Disconnect from peer, if any.
1615          */
1616         ppipe = cpipe->pipe_peer;
1617         if (ppipe->pipe_present == PIPE_ACTIVE) {
1618                 pipeselwakeup(ppipe);
1619
1620                 ppipe->pipe_state |= PIPE_EOF;
1621                 wakeup(ppipe);
1622                 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0);
1623         }
1624
1625         /*
1626          * Mark this endpoint as free.  Release kmem resources.  We
1627          * don't mark this endpoint as unused until we've finished
1628          * doing that, or the pipe might disappear out from under
1629          * us.
1630          */
1631         PIPE_UNLOCK(cpipe);
1632         pipe_free_kmem(cpipe);
1633         PIPE_LOCK(cpipe);
1634         cpipe->pipe_present = PIPE_CLOSING;
1635         pipeunlock(cpipe);
1636
1637         /*
1638          * knlist_clear() may sleep dropping the PIPE_MTX. Set the
1639          * PIPE_FINALIZED, that allows other end to free the
1640          * pipe_pair, only after the knotes are completely dismantled.
1641          */
1642         knlist_clear(&cpipe->pipe_sel.si_note, 1);
1643         cpipe->pipe_present = PIPE_FINALIZED;
1644         seldrain(&cpipe->pipe_sel);
1645         knlist_destroy(&cpipe->pipe_sel.si_note);
1646
1647         /*
1648          * If both endpoints are now closed, release the memory for the
1649          * pipe pair.  If not, unlock.
1650          */
1651         if (ppipe->pipe_present == PIPE_FINALIZED) {
1652                 PIPE_UNLOCK(cpipe);
1653 #ifdef MAC
1654                 mac_pipe_destroy(pp);
1655 #endif
1656                 uma_zfree(pipe_zone, cpipe->pipe_pair);
1657         } else
1658                 PIPE_UNLOCK(cpipe);
1659 }
1660
1661 /*ARGSUSED*/
1662 static int
1663 pipe_kqfilter(struct file *fp, struct knote *kn)
1664 {
1665         struct pipe *cpipe;
1666
1667         /*
1668          * If a filter is requested that is not supported by this file
1669          * descriptor, don't return an error, but also don't ever generate an
1670          * event.
1671          */
1672         if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) {
1673                 kn->kn_fop = &pipe_nfiltops;
1674                 return (0);
1675         }
1676         if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) {
1677                 kn->kn_fop = &pipe_nfiltops;
1678                 return (0);
1679         }
1680         cpipe = fp->f_data;
1681         PIPE_LOCK(cpipe);
1682         switch (kn->kn_filter) {
1683         case EVFILT_READ:
1684                 kn->kn_fop = &pipe_rfiltops;
1685                 break;
1686         case EVFILT_WRITE:
1687                 kn->kn_fop = &pipe_wfiltops;
1688                 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) {
1689                         /* other end of pipe has been closed */
1690                         PIPE_UNLOCK(cpipe);
1691                         return (EPIPE);
1692                 }
1693                 cpipe = PIPE_PEER(cpipe);
1694                 break;
1695         default:
1696                 PIPE_UNLOCK(cpipe);
1697                 return (EINVAL);
1698         }
1699
1700         kn->kn_hook = cpipe;
1701         knlist_add(&cpipe->pipe_sel.si_note, kn, 1);
1702         PIPE_UNLOCK(cpipe);
1703         return (0);
1704 }
1705
1706 static void
1707 filt_pipedetach(struct knote *kn)
1708 {
1709         struct pipe *cpipe = kn->kn_hook;
1710
1711         PIPE_LOCK(cpipe);
1712         knlist_remove(&cpipe->pipe_sel.si_note, kn, 1);
1713         PIPE_UNLOCK(cpipe);
1714 }
1715
1716 /*ARGSUSED*/
1717 static int
1718 filt_piperead(struct knote *kn, long hint)
1719 {
1720         struct pipe *rpipe = kn->kn_hook;
1721         struct pipe *wpipe = rpipe->pipe_peer;
1722         int ret;
1723
1724         PIPE_LOCK_ASSERT(rpipe, MA_OWNED);
1725         kn->kn_data = rpipe->pipe_buffer.cnt;
1726         if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
1727                 kn->kn_data = rpipe->pipe_map.cnt;
1728
1729         if ((rpipe->pipe_state & PIPE_EOF) ||
1730             wpipe->pipe_present != PIPE_ACTIVE ||
1731             (wpipe->pipe_state & PIPE_EOF)) {
1732                 kn->kn_flags |= EV_EOF;
1733                 return (1);
1734         }
1735         ret = kn->kn_data > 0;
1736         return ret;
1737 }
1738
1739 /*ARGSUSED*/
1740 static int
1741 filt_pipewrite(struct knote *kn, long hint)
1742 {
1743         struct pipe *wpipe;
1744
1745         /*
1746          * If this end of the pipe is closed, the knote was removed from the
1747          * knlist and the list lock (i.e., the pipe lock) is therefore not held.
1748          */
1749         wpipe = kn->kn_hook;
1750         if (wpipe->pipe_present != PIPE_ACTIVE ||
1751             (wpipe->pipe_state & PIPE_EOF)) {
1752                 kn->kn_data = 0;
1753                 kn->kn_flags |= EV_EOF;
1754                 return (1);
1755         }
1756         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
1757         kn->kn_data = (wpipe->pipe_buffer.size > 0) ?
1758             (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF;
1759         if (wpipe->pipe_state & PIPE_DIRECTW)
1760                 kn->kn_data = 0;
1761
1762         return (kn->kn_data >= PIPE_BUF);
1763 }
1764
1765 static void
1766 filt_pipedetach_notsup(struct knote *kn)
1767 {
1768
1769 }
1770
1771 static int
1772 filt_pipenotsup(struct knote *kn, long hint)
1773 {
1774
1775         return (0);
1776 }