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/user.h>
 119 #include <sys/event.h>
 120
 121 #include <security/mac/mac_framework.h>
 122
 123 #include <vm/vm.h>
 124 #include <vm/vm_param.h>
 125 #include <vm/vm_object.h>
 126 #include <vm/vm_kern.h>
 127 #include <vm/vm_extern.h>
 128 #include <vm/pmap.h>
 129 #include <vm/vm_map.h>
 130 #include <vm/vm_page.h>
 131 #include <vm/uma.h>
 132
 133 /*
 134  * Use this define if you want to disable *fancy* VM things.  Expect an
 135  * approx 30% decrease in transfer rate.  This could be useful for
 136  * NetBSD or OpenBSD.
 137  */
 138 /* #define PIPE_NODIRECT */
 139
 140 #define PIPE_PEER(pipe) \
 141         (((pipe)->pipe_state & PIPE_NAMED) ? (pipe) : ((pipe)->pipe_peer))
 142
 143 /*
 144  * interfaces to the outside world
 145  */
 146 static fo_rdwr_t        pipe_read;
 147 static fo_rdwr_t        pipe_write;
 148 static fo_truncate_t    pipe_truncate;
 149 static fo_ioctl_t       pipe_ioctl;
 150 static fo_poll_t        pipe_poll;
 151 static fo_kqfilter_t    pipe_kqfilter;
 152 static fo_stat_t        pipe_stat;
 153 static fo_close_t       pipe_close;
 154 static fo_chmod_t       pipe_chmod;
 155 static fo_chown_t       pipe_chown;
 156 static fo_fill_kinfo_t  pipe_fill_kinfo;
 157
 158 struct fileops pipeops = {
 159         .fo_read = pipe_read,
 160         .fo_write = pipe_write,
 161         .fo_truncate = pipe_truncate,
 162         .fo_ioctl = pipe_ioctl,
 163         .fo_poll = pipe_poll,
 164         .fo_kqfilter = pipe_kqfilter,
 165         .fo_stat = pipe_stat,
 166         .fo_close = pipe_close,
 167         .fo_chmod = pipe_chmod,
 168         .fo_chown = pipe_chown,
 169         .fo_sendfile = invfo_sendfile,
 170         .fo_fill_kinfo = pipe_fill_kinfo,
 171         .fo_flags = DFLAG_PASSABLE
 172 };
 173
 174 static void     filt_pipedetach(struct knote *kn);
 175 static void     filt_pipedetach_notsup(struct knote *kn);
 176 static int      filt_pipenotsup(struct knote *kn, long hint);
 177 static int      filt_piperead(struct knote *kn, long hint);
 178 static int      filt_pipewrite(struct knote *kn, long hint);
 179
 180 static struct filterops pipe_nfiltops = {
 181         .f_isfd = 1,
 182         .f_detach = filt_pipedetach_notsup,
 183         .f_event = filt_pipenotsup
 184 };
 185 static struct filterops pipe_rfiltops = {
 186         .f_isfd = 1,
 187         .f_detach = filt_pipedetach,
 188         .f_event = filt_piperead
 189 };
 190 static struct filterops pipe_wfiltops = {
 191         .f_isfd = 1,
 192         .f_detach = filt_pipedetach,
 193         .f_event = filt_pipewrite
 194 };
 195
 196 /*
 197  * Default pipe buffer size(s), this can be kind-of large now because pipe
 198  * space is pageable.  The pipe code will try to maintain locality of
 199  * reference for performance reasons, so small amounts of outstanding I/O
 200  * will not wipe the cache.
 201  */
 202 #define MINPIPESIZE (PIPE_SIZE/3)
 203 #define MAXPIPESIZE (2*PIPE_SIZE/3)
 204
 205 static long amountpipekva;
 206 static int pipefragretry;
 207 static int pipeallocfail;
 208 static int piperesizefail;
 209 static int piperesizeallowed = 1;
 210
 211 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
 212            &maxpipekva, 0, "Pipe KVA limit");
 213 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD,
 214            &amountpipekva, 0, "Pipe KVA usage");
 215 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD,
 216           &pipefragretry, 0, "Pipe allocation retries due to fragmentation");
 217 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD,
 218           &pipeallocfail, 0, "Pipe allocation failures");
 219 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD,
 220           &piperesizefail, 0, "Pipe resize failures");
 221 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW,
 222           &piperesizeallowed, 0, "Pipe resizing allowed");
 223
 224 static void pipeinit(void *dummy __unused);
 225 static void pipeclose(struct pipe *cpipe);
 226 static void pipe_free_kmem(struct pipe *cpipe);
 227 static void pipe_create(struct pipe *pipe, int backing);
 228 static void pipe_paircreate(struct thread *td, struct pipepair **p_pp);
 229 static __inline int pipelock(struct pipe *cpipe, int catch);
 230 static __inline void pipeunlock(struct pipe *cpipe);
 231 #ifndef PIPE_NODIRECT
 232 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio);
 233 static void pipe_destroy_write_buffer(struct pipe *wpipe);
 234 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio);
 235 static void pipe_clone_write_buffer(struct pipe *wpipe);
 236 #endif
 237 static int pipespace(struct pipe *cpipe, int size);
 238 static int pipespace_new(struct pipe *cpipe, int size);
 239
 240 static int      pipe_zone_ctor(void *mem, int size, void *arg, int flags);
 241 static int      pipe_zone_init(void *mem, int size, int flags);
 242 static void     pipe_zone_fini(void *mem, int size);
 243
 244 static uma_zone_t pipe_zone;
 245 static struct unrhdr *pipeino_unr;
 246 static dev_t pipedev_ino;
 247
 248 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
 249
 250 static void
 251 pipeinit(void *dummy __unused)
 252 {
 253
 254         pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair),
 255             pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini,
 256             UMA_ALIGN_PTR, 0);
 257         KASSERT(pipe_zone != NULL, ("pipe_zone not initialized"));
 258         pipeino_unr = new_unrhdr(1, INT32_MAX, NULL);
 259         KASSERT(pipeino_unr != NULL, ("pipe fake inodes not initialized"));
 260         pipedev_ino = devfs_alloc_cdp_inode();
 261         KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized"));
 262 }
 263
 264 static int
 265 pipe_zone_ctor(void *mem, int size, void *arg, int flags)
 266 {
 267         struct pipepair *pp;
 268         struct pipe *rpipe, *wpipe;
 269
 270         KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size"));
 271
 272         pp = (struct pipepair *)mem;
 273
 274         /*
 275          * We zero both pipe endpoints to make sure all the kmem pointers
 276          * are NULL, flag fields are zero'd, etc.  We timestamp both
 277          * endpoints with the same time.
 278          */
 279         rpipe = &pp->pp_rpipe;
 280         bzero(rpipe, sizeof(*rpipe));
 281         vfs_timestamp(&rpipe->pipe_ctime);
 282         rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime;
 283
 284         wpipe = &pp->pp_wpipe;
 285         bzero(wpipe, sizeof(*wpipe));
 286         wpipe->pipe_ctime = rpipe->pipe_ctime;
 287         wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime;
 288
 289         rpipe->pipe_peer = wpipe;
 290         rpipe->pipe_pair = pp;
 291         wpipe->pipe_peer = rpipe;
 292         wpipe->pipe_pair = pp;
 293
 294         /*
 295          * Mark both endpoints as present; they will later get free'd
 296          * one at a time.  When both are free'd, then the whole pair
 297          * is released.
 298          */
 299         rpipe->pipe_present = PIPE_ACTIVE;
 300         wpipe->pipe_present = PIPE_ACTIVE;
 301
 302         /*
 303          * Eventually, the MAC Framework may initialize the label
 304          * in ctor or init, but for now we do it elswhere to avoid
 305          * blocking in ctor or init.
 306          */
 307         pp->pp_label = NULL;
 308
 309         return (0);
 310 }
 311
 312 static int
 313 pipe_zone_init(void *mem, int size, int flags)
 314 {
 315         struct pipepair *pp;
 316
 317         KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size"));
 318
 319         pp = (struct pipepair *)mem;
 320
 321         mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_RECURSE);
 322         return (0);
 323 }
 324
 325 static void
 326 pipe_zone_fini(void *mem, int size)
 327 {
 328         struct pipepair *pp;
 329
 330         KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size"));
 331
 332         pp = (struct pipepair *)mem;
 333
 334         mtx_destroy(&pp->pp_mtx);
 335 }
 336
 337 static void
 338 pipe_paircreate(struct thread *td, struct pipepair **p_pp)
 339 {
 340         struct pipepair *pp;
 341         struct pipe *rpipe, *wpipe;
 342
 343         *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK);
 344 #ifdef MAC
 345         /*
 346          * The MAC label is shared between the connected endpoints.  As a
 347          * result mac_pipe_init() and mac_pipe_create() are called once
 348          * for the pair, and not on the endpoints.
 349          */
 350         mac_pipe_init(pp);
 351         mac_pipe_create(td->td_ucred, pp);
 352 #endif
 353         rpipe = &pp->pp_rpipe;
 354         wpipe = &pp->pp_wpipe;
 355
 356         knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe));
 357         knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe));
 358
 359         /* Only the forward direction pipe is backed by default */
 360         pipe_create(rpipe, 1);
 361         pipe_create(wpipe, 0);
 362
 363         rpipe->pipe_state |= PIPE_DIRECTOK;
 364         wpipe->pipe_state |= PIPE_DIRECTOK;
 365 }
 366
 367 void
 368 pipe_named_ctor(struct pipe **ppipe, struct thread *td)
 369 {
 370         struct pipepair *pp;
 371
 372         pipe_paircreate(td, &pp);
 373         pp->pp_rpipe.pipe_state |= PIPE_NAMED;
 374         *ppipe = &pp->pp_rpipe;
 375 }
 376
 377 void
 378 pipe_dtor(struct pipe *dpipe)
 379 {
 380         ino_t ino;
 381
 382         ino = dpipe->pipe_ino;
 383         funsetown(&dpipe->pipe_sigio);
 384         pipeclose(dpipe);
 385         if (dpipe->pipe_state & PIPE_NAMED) {
 386                 dpipe = dpipe->pipe_peer;
 387                 funsetown(&dpipe->pipe_sigio);
 388                 pipeclose(dpipe);
 389         }
 390         if (ino != 0 && ino != (ino_t)-1)
 391                 free_unr(pipeino_unr, ino);
 392 }
 393
 394 /*
 395  * The pipe system call for the DTYPE_PIPE type of pipes.  If we fail, let
 396  * the zone pick up the pieces via pipeclose().
 397  */
 398 int
 399 kern_pipe(struct thread *td, int fildes[2])
 400 {
 401
 402         return (kern_pipe2(td, fildes, 0));
 403 }
 404
 405 int
 406 kern_pipe2(struct thread *td, int fildes[2], int flags)
 407 {
 408         struct filedesc *fdp;
 409         struct file *rf, *wf;
 410         struct pipe *rpipe, *wpipe;
 411         struct pipepair *pp;
 412         int fd, fflags, error;
 413
 414         fdp = td->td_proc->p_fd;
 415         pipe_paircreate(td, &pp);
 416         rpipe = &pp->pp_rpipe;
 417         wpipe = &pp->pp_wpipe;
 418         error = falloc(td, &rf, &fd, flags);
 419         if (error) {
 420                 pipeclose(rpipe);
 421                 pipeclose(wpipe);
 422                 return (error);
 423         }
 424         /* An extra reference on `rf' has been held for us by falloc(). */
 425         fildes[0] = fd;
 426
 427         fflags = FREAD | FWRITE;
 428         if ((flags & O_NONBLOCK) != 0)
 429                 fflags |= FNONBLOCK;
 430
 431         /*
 432          * Warning: once we've gotten past allocation of the fd for the
 433          * read-side, we can only drop the read side via fdrop() in order
 434          * to avoid races against processes which manage to dup() the read
 435          * side while we are blocked trying to allocate the write side.
 436          */
 437         finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops);
 438         error = falloc(td, &wf, &fd, flags);
 439         if (error) {
 440                 fdclose(fdp, rf, fildes[0], td);
 441                 fdrop(rf, td);
 442                 /* rpipe has been closed by fdrop(). */
 443                 pipeclose(wpipe);
 444                 return (error);
 445         }
 446         /* An extra reference on `wf' has been held for us by falloc(). */
 447         finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops);
 448         fdrop(wf, td);
 449         fildes[1] = fd;
 450         fdrop(rf, td);
 451
 452         return (0);
 453 }
 454
 455 /* ARGSUSED */
 456 int
 457 sys_pipe(struct thread *td, struct pipe_args *uap)
 458 {
 459         int error;
 460         int fildes[2];
 461
 462         error = kern_pipe(td, fildes);
 463         if (error)
 464                 return (error);
 465
 466         td->td_retval[0] = fildes[0];
 467         td->td_retval[1] = fildes[1];
 468
 469         return (0);
 470 }
 471
 472 int
 473 sys_pipe2(struct thread *td, struct pipe2_args *uap)
 474 {
 475         int error, fildes[2];
 476
 477         if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK))
 478                 return (EINVAL);
 479         error = kern_pipe2(td, fildes, uap->flags);
 480         if (error)
 481                 return (error);
 482         error = copyout(fildes, uap->fildes, 2 * sizeof(int));
 483         if (error) {
 484                 (void)kern_close(td, fildes[0]);
 485                 (void)kern_close(td, fildes[1]);
 486         }
 487         return (error);
 488 }
 489
 490 /*
 491  * Allocate kva for pipe circular buffer, the space is pageable
 492  * This routine will 'realloc' the size of a pipe safely, if it fails
 493  * it will retain the old buffer.
 494  * If it fails it will return ENOMEM.
 495  */
 496 static int
 497 pipespace_new(cpipe, size)
 498         struct pipe *cpipe;
 499         int size;
 500 {
 501         caddr_t buffer;
 502         int error, cnt, firstseg;
 503         static int curfail = 0;
 504         static struct timeval lastfail;
 505
 506         KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked"));
 507         KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW),
 508                 ("pipespace: resize of direct writes not allowed"));
 509 retry:
 510         cnt = cpipe->pipe_buffer.cnt;
 511         if (cnt > size)
 512                 size = cnt;
 513
 514         size = round_page(size);
 515         buffer = (caddr_t) vm_map_min(pipe_map);
 516
 517         error = vm_map_find(pipe_map, NULL, 0,
 518                 (vm_offset_t *) &buffer, size, 0, VMFS_ANY_SPACE,
 519                 VM_PROT_ALL, VM_PROT_ALL, 0);
 520         if (error != KERN_SUCCESS) {
 521                 if ((cpipe->pipe_buffer.buffer == NULL) &&
 522                         (size > SMALL_PIPE_SIZE)) {
 523                         size = SMALL_PIPE_SIZE;
 524                         pipefragretry++;
 525                         goto retry;
 526                 }
 527                 if (cpipe->pipe_buffer.buffer == NULL) {
 528                         pipeallocfail++;
 529                         if (ppsratecheck(&lastfail, &curfail, 1))
 530                                 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n");
 531                 } else {
 532                         piperesizefail++;
 533                 }
 534                 return (ENOMEM);
 535         }
 536
 537         /* copy data, then free old resources if we're resizing */
 538         if (cnt > 0) {
 539                 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) {
 540                         firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out;
 541                         bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
 542                                 buffer, firstseg);
 543                         if ((cnt - firstseg) > 0)
 544                                 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg],
 545                                         cpipe->pipe_buffer.in);
 546                 } else {
 547                         bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
 548                                 buffer, cnt);
 549                 }
 550         }
 551         pipe_free_kmem(cpipe);
 552         cpipe->pipe_buffer.buffer = buffer;
 553         cpipe->pipe_buffer.size = size;
 554         cpipe->pipe_buffer.in = cnt;
 555         cpipe->pipe_buffer.out = 0;
 556         cpipe->pipe_buffer.cnt = cnt;
 557         atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size);
 558         return (0);
 559 }
 560
 561 /*
 562  * Wrapper for pipespace_new() that performs locking assertions.
 563  */
 564 static int
 565 pipespace(cpipe, size)
 566         struct pipe *cpipe;
 567         int size;
 568 {
 569
 570         KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
 571                 ("Unlocked pipe passed to pipespace"));
 572         return (pipespace_new(cpipe, size));
 573 }
 574
 575 /*
 576  * lock a pipe for I/O, blocking other access
 577  */
 578 static __inline int
 579 pipelock(cpipe, catch)
 580         struct pipe *cpipe;
 581         int catch;
 582 {
 583         int error;
 584
 585         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 586         while (cpipe->pipe_state & PIPE_LOCKFL) {
 587                 cpipe->pipe_state |= PIPE_LWANT;
 588                 error = msleep(cpipe, PIPE_MTX(cpipe),
 589                     catch ? (PRIBIO | PCATCH) : PRIBIO,
 590                     "pipelk", 0);
 591                 if (error != 0)
 592                         return (error);
 593         }
 594         cpipe->pipe_state |= PIPE_LOCKFL;
 595         return (0);
 596 }
 597
 598 /*
 599  * unlock a pipe I/O lock
 600  */
 601 static __inline void
 602 pipeunlock(cpipe)
 603         struct pipe *cpipe;
 604 {
 605
 606         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 607         KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
 608                 ("Unlocked pipe passed to pipeunlock"));
 609         cpipe->pipe_state &= ~PIPE_LOCKFL;
 610         if (cpipe->pipe_state & PIPE_LWANT) {
 611                 cpipe->pipe_state &= ~PIPE_LWANT;
 612                 wakeup(cpipe);
 613         }
 614 }
 615
 616 void
 617 pipeselwakeup(cpipe)
 618         struct pipe *cpipe;
 619 {
 620
 621         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
 622         if (cpipe->pipe_state & PIPE_SEL) {
 623                 selwakeuppri(&cpipe->pipe_sel, PSOCK);
 624                 if (!SEL_WAITING(&cpipe->pipe_sel))
 625                         cpipe->pipe_state &= ~PIPE_SEL;
 626         }
 627         if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
 628                 pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
 629         KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0);
 630 }
 631
 632 /*
 633  * Initialize and allocate VM and memory for pipe.  The structure
 634  * will start out zero'd from the ctor, so we just manage the kmem.
 635  */
 636 static void
 637 pipe_create(pipe, backing)
 638         struct pipe *pipe;
 639         int backing;
 640 {
 641
 642         if (backing) {
 643                 /*
 644                  * Note that these functions can fail if pipe map is exhausted
 645                  * (as a result of too many pipes created), but we ignore the
 646                  * error as it is not fatal and could be provoked by
 647                  * unprivileged users. The only consequence is worse performance
 648                  * with given pipe.
 649                  */
 650                 if (amountpipekva > maxpipekva / 2)
 651                         (void)pipespace_new(pipe, SMALL_PIPE_SIZE);
 652                 else
 653                         (void)pipespace_new(pipe, PIPE_SIZE);
 654         }
 655
 656         pipe->pipe_ino = -1;
 657 }
 658
 659 /* ARGSUSED */
 660 static int
 661 pipe_read(fp, uio, active_cred, flags, td)
 662         struct file *fp;
 663         struct uio *uio;
 664         struct ucred *active_cred;
 665         struct thread *td;
 666         int flags;
 667 {
 668         struct pipe *rpipe;
 669         int error;
 670         int nread = 0;
 671         int size;
 672
 673         rpipe = fp->f_data;
 674         PIPE_LOCK(rpipe);
 675         ++rpipe->pipe_busy;
 676         error = pipelock(rpipe, 1);
 677         if (error)
 678                 goto unlocked_error;
 679
 680 #ifdef MAC
 681         error = mac_pipe_check_read(active_cred, rpipe->pipe_pair);
 682         if (error)
 683                 goto locked_error;
 684 #endif
 685         if (amountpipekva > (3 * maxpipekva) / 4) {
 686                 if (!(rpipe->pipe_state & PIPE_DIRECTW) &&
 687                         (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
 688                         (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
 689                         (piperesizeallowed == 1)) {
 690                         PIPE_UNLOCK(rpipe);
 691                         pipespace(rpipe, SMALL_PIPE_SIZE);
 692                         PIPE_LOCK(rpipe);
 693                 }
 694         }
 695
 696         while (uio->uio_resid) {
 697                 /*
 698                  * normal pipe buffer receive
 699                  */
 700                 if (rpipe->pipe_buffer.cnt > 0) {
 701                         size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
 702                         if (size > rpipe->pipe_buffer.cnt)
 703                                 size = rpipe->pipe_buffer.cnt;
 704                         if (size > uio->uio_resid)
 705                                 size = uio->uio_resid;
 706
 707                         PIPE_UNLOCK(rpipe);
 708                         error = uiomove(
 709                             &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
 710                             size, uio);
 711                         PIPE_LOCK(rpipe);
 712                         if (error)
 713                                 break;
 714
 715                         rpipe->pipe_buffer.out += size;
 716                         if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
 717                                 rpipe->pipe_buffer.out = 0;
 718
 719                         rpipe->pipe_buffer.cnt -= size;
 720
 721                         /*
 722                          * If there is no more to read in the pipe, reset
 723                          * its pointers to the beginning.  This improves
 724                          * cache hit stats.
 725                          */
 726                         if (rpipe->pipe_buffer.cnt == 0) {
 727                                 rpipe->pipe_buffer.in = 0;
 728                                 rpipe->pipe_buffer.out = 0;
 729                         }
 730                         nread += size;
 731 #ifndef PIPE_NODIRECT
 732                 /*
 733                  * Direct copy, bypassing a kernel buffer.
 734                  */
 735                 } else if ((size = rpipe->pipe_map.cnt) &&
 736                            (rpipe->pipe_state & PIPE_DIRECTW)) {
 737                         if (size > uio->uio_resid)
 738                                 size = (u_int) uio->uio_resid;
 739
 740                         PIPE_UNLOCK(rpipe);
 741                         error = uiomove_fromphys(rpipe->pipe_map.ms,
 742                             rpipe->pipe_map.pos, size, uio);
 743                         PIPE_LOCK(rpipe);
 744                         if (error)
 745                                 break;
 746                         nread += size;
 747                         rpipe->pipe_map.pos += size;
 748                         rpipe->pipe_map.cnt -= size;
 749                         if (rpipe->pipe_map.cnt == 0) {
 750                                 rpipe->pipe_state &= ~(PIPE_DIRECTW|PIPE_WANTW);
 751                                 wakeup(rpipe);
 752                         }
 753 #endif
 754                 } else {
 755                         /*
 756                          * detect EOF condition
 757                          * read returns 0 on EOF, no need to set error
 758                          */
 759                         if (rpipe->pipe_state & PIPE_EOF)
 760                                 break;
 761
 762                         /*
 763                          * If the "write-side" has been blocked, wake it up now.
 764                          */
 765                         if (rpipe->pipe_state & PIPE_WANTW) {
 766                                 rpipe->pipe_state &= ~PIPE_WANTW;
 767                                 wakeup(rpipe);
 768                         }
 769
 770                         /*
 771                          * Break if some data was read.
 772                          */
 773                         if (nread > 0)
 774                                 break;
 775
 776                         /*
 777                          * Unlock the pipe buffer for our remaining processing.
 778                          * We will either break out with an error or we will
 779                          * sleep and relock to loop.
 780                          */
 781                         pipeunlock(rpipe);
 782
 783                         /*
 784                          * Handle non-blocking mode operation or
 785                          * wait for more data.
 786                          */
 787                         if (fp->f_flag & FNONBLOCK) {
 788                                 error = EAGAIN;
 789                         } else {
 790                                 rpipe->pipe_state |= PIPE_WANTR;
 791                                 if ((error = msleep(rpipe, PIPE_MTX(rpipe),
 792                                     PRIBIO | PCATCH,
 793                                     "piperd", 0)) == 0)
 794                                         error = pipelock(rpipe, 1);
 795                         }
 796                         if (error)
 797                                 goto unlocked_error;
 798                 }
 799         }
 800 #ifdef MAC
 801 locked_error:
 802 #endif
 803         pipeunlock(rpipe);
 804
 805         /* XXX: should probably do this before getting any locks. */
 806         if (error == 0)
 807                 vfs_timestamp(&rpipe->pipe_atime);
 808 unlocked_error:
 809         --rpipe->pipe_busy;
 810
 811         /*
 812          * PIPE_WANT processing only makes sense if pipe_busy is 0.
 813          */
 814         if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
 815                 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
 816                 wakeup(rpipe);
 817         } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
 818                 /*
 819                  * Handle write blocking hysteresis.
 820                  */
 821                 if (rpipe->pipe_state & PIPE_WANTW) {
 822                         rpipe->pipe_state &= ~PIPE_WANTW;
 823                         wakeup(rpipe);
 824                 }
 825         }
 826
 827         if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
 828                 pipeselwakeup(rpipe);
 829
 830         PIPE_UNLOCK(rpipe);
 831         return (error);
 832 }
 833
 834 #ifndef PIPE_NODIRECT
 835 /*
 836  * Map the sending processes' buffer into kernel space and wire it.
 837  * This is similar to a physical write operation.
 838  */
 839 static int
 840 pipe_build_write_buffer(wpipe, uio)
 841         struct pipe *wpipe;
 842         struct uio *uio;
 843 {
 844         u_int size;
 845         int i;
 846
 847         PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED);
 848         KASSERT(wpipe->pipe_state & PIPE_DIRECTW,
 849                 ("Clone attempt on non-direct write pipe!"));
 850
 851         if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size)
 852                 size = wpipe->pipe_buffer.size;
 853         else
 854                 size = uio->uio_iov->iov_len;
 855
 856         if ((i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
 857             (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ,
 858             wpipe->pipe_map.ms, PIPENPAGES)) < 0)
 859                 return (EFAULT);
 860
 861 /*
 862  * set up the control block
 863  */
 864         wpipe->pipe_map.npages = i;
 865         wpipe->pipe_map.pos =
 866             ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK;
 867         wpipe->pipe_map.cnt = size;
 868
 869 /*
 870  * and update the uio data
 871  */
 872
 873         uio->uio_iov->iov_len -= size;
 874         uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size;
 875         if (uio->uio_iov->iov_len == 0)
 876                 uio->uio_iov++;
 877         uio->uio_resid -= size;
 878         uio->uio_offset += size;
 879         return (0);
 880 }
 881
 882 /*
 883  * unmap and unwire the process buffer
 884  */
 885 static void
 886 pipe_destroy_write_buffer(wpipe)
 887         struct pipe *wpipe;
 888 {
 889
 890         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 891         vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages);
 892         wpipe->pipe_map.npages = 0;
 893 }
 894
 895 /*
 896  * In the case of a signal, the writing process might go away.  This
 897  * code copies the data into the circular buffer so that the source
 898  * pages can be freed without loss of data.
 899  */
 900 static void
 901 pipe_clone_write_buffer(wpipe)
 902         struct pipe *wpipe;
 903 {
 904         struct uio uio;
 905         struct iovec iov;
 906         int size;
 907         int pos;
 908
 909         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 910         size = wpipe->pipe_map.cnt;
 911         pos = wpipe->pipe_map.pos;
 912
 913         wpipe->pipe_buffer.in = size;
 914         wpipe->pipe_buffer.out = 0;
 915         wpipe->pipe_buffer.cnt = size;
 916         wpipe->pipe_state &= ~PIPE_DIRECTW;
 917
 918         PIPE_UNLOCK(wpipe);
 919         iov.iov_base = wpipe->pipe_buffer.buffer;
 920         iov.iov_len = size;
 921         uio.uio_iov = &iov;
 922         uio.uio_iovcnt = 1;
 923         uio.uio_offset = 0;
 924         uio.uio_resid = size;
 925         uio.uio_segflg = UIO_SYSSPACE;
 926         uio.uio_rw = UIO_READ;
 927         uio.uio_td = curthread;
 928         uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio);
 929         PIPE_LOCK(wpipe);
 930         pipe_destroy_write_buffer(wpipe);
 931 }
 932
 933 /*
 934  * This implements the pipe buffer write mechanism.  Note that only
 935  * a direct write OR a normal pipe write can be pending at any given time.
 936  * If there are any characters in the pipe buffer, the direct write will
 937  * be deferred until the receiving process grabs all of the bytes from
 938  * the pipe buffer.  Then the direct mapping write is set-up.
 939  */
 940 static int
 941 pipe_direct_write(wpipe, uio)
 942         struct pipe *wpipe;
 943         struct uio *uio;
 944 {
 945         int error;
 946
 947 retry:
 948         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 949         error = pipelock(wpipe, 1);
 950         if (wpipe->pipe_state & PIPE_EOF)
 951                 error = EPIPE;
 952         if (error) {
 953                 pipeunlock(wpipe);
 954                 goto error1;
 955         }
 956         while (wpipe->pipe_state & PIPE_DIRECTW) {
 957                 if (wpipe->pipe_state & PIPE_WANTR) {
 958                         wpipe->pipe_state &= ~PIPE_WANTR;
 959                         wakeup(wpipe);
 960                 }
 961                 pipeselwakeup(wpipe);
 962                 wpipe->pipe_state |= PIPE_WANTW;
 963                 pipeunlock(wpipe);
 964                 error = msleep(wpipe, PIPE_MTX(wpipe),
 965                     PRIBIO | PCATCH, "pipdww", 0);
 966                 if (error)
 967                         goto error1;
 968                 else
 969                         goto retry;
 970         }
 971         wpipe->pipe_map.cnt = 0;        /* transfer not ready yet */
 972         if (wpipe->pipe_buffer.cnt > 0) {
 973                 if (wpipe->pipe_state & PIPE_WANTR) {
 974                         wpipe->pipe_state &= ~PIPE_WANTR;
 975                         wakeup(wpipe);
 976                 }
 977                 pipeselwakeup(wpipe);
 978                 wpipe->pipe_state |= PIPE_WANTW;
 979                 pipeunlock(wpipe);
 980                 error = msleep(wpipe, PIPE_MTX(wpipe),
 981                     PRIBIO | PCATCH, "pipdwc", 0);
 982                 if (error)
 983                         goto error1;
 984                 else
 985                         goto retry;
 986         }
 987
 988         wpipe->pipe_state |= PIPE_DIRECTW;
 989
 990         PIPE_UNLOCK(wpipe);
 991         error = pipe_build_write_buffer(wpipe, uio);
 992         PIPE_LOCK(wpipe);
 993         if (error) {
 994                 wpipe->pipe_state &= ~PIPE_DIRECTW;
 995                 pipeunlock(wpipe);
 996                 goto error1;
 997         }
 998
 999         error = 0;
1000         while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
1001                 if (wpipe->pipe_state & PIPE_EOF) {
1002                         pipe_destroy_write_buffer(wpipe);
1003                         pipeselwakeup(wpipe);
1004                         pipeunlock(wpipe);
1005                         error = EPIPE;
1006                         goto error1;
1007                 }
1008                 if (wpipe->pipe_state & PIPE_WANTR) {
1009                         wpipe->pipe_state &= ~PIPE_WANTR;
1010                         wakeup(wpipe);
1011                 }
1012                 pipeselwakeup(wpipe);
1013                 wpipe->pipe_state |= PIPE_WANTW;
1014                 pipeunlock(wpipe);
1015                 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
1016                     "pipdwt", 0);
1017                 pipelock(wpipe, 0);
1018         }
1019
1020         if (wpipe->pipe_state & PIPE_EOF)
1021                 error = EPIPE;
1022         if (wpipe->pipe_state & PIPE_DIRECTW) {
1023                 /*
1024                  * this bit of trickery substitutes a kernel buffer for
1025                  * the process that might be going away.
1026                  */
1027                 pipe_clone_write_buffer(wpipe);
1028         } else {
1029                 pipe_destroy_write_buffer(wpipe);
1030         }
1031         pipeunlock(wpipe);
1032         return (error);
1033
1034 error1:
1035         wakeup(wpipe);
1036         return (error);
1037 }
1038 #endif
1039
1040 static int
1041 pipe_write(fp, uio, active_cred, flags, td)
1042         struct file *fp;
1043         struct uio *uio;
1044         struct ucred *active_cred;
1045         struct thread *td;
1046         int flags;
1047 {
1048         int error = 0;
1049         int desiredsize;
1050         ssize_t orig_resid;
1051         struct pipe *wpipe, *rpipe;
1052
1053         rpipe = fp->f_data;
1054         wpipe = PIPE_PEER(rpipe);
1055         PIPE_LOCK(rpipe);
1056         error = pipelock(wpipe, 1);
1057         if (error) {
1058                 PIPE_UNLOCK(rpipe);
1059                 return (error);
1060         }
1061         /*
1062          * detect loss of pipe read side, issue SIGPIPE if lost.
1063          */
1064         if (wpipe->pipe_present != PIPE_ACTIVE ||
1065             (wpipe->pipe_state & PIPE_EOF)) {
1066                 pipeunlock(wpipe);
1067                 PIPE_UNLOCK(rpipe);
1068                 return (EPIPE);
1069         }
1070 #ifdef MAC
1071         error = mac_pipe_check_write(active_cred, wpipe->pipe_pair);
1072         if (error) {
1073                 pipeunlock(wpipe);
1074                 PIPE_UNLOCK(rpipe);
1075                 return (error);
1076         }
1077 #endif
1078         ++wpipe->pipe_busy;
1079
1080         /* Choose a larger size if it's advantageous */
1081         desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size);
1082         while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) {
1083                 if (piperesizeallowed != 1)
1084                         break;
1085                 if (amountpipekva > maxpipekva / 2)
1086                         break;
1087                 if (desiredsize == BIG_PIPE_SIZE)
1088                         break;
1089                 desiredsize = desiredsize * 2;
1090         }
1091
1092         /* Choose a smaller size if we're in a OOM situation */
1093         if ((amountpipekva > (3 * maxpipekva) / 4) &&
1094                 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
1095                 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
1096                 (piperesizeallowed == 1))
1097                 desiredsize = SMALL_PIPE_SIZE;
1098
1099         /* Resize if the above determined that a new size was necessary */
1100         if ((desiredsize != wpipe->pipe_buffer.size) &&
1101                 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) {
1102                 PIPE_UNLOCK(wpipe);
1103                 pipespace(wpipe, desiredsize);
1104                 PIPE_LOCK(wpipe);
1105         }
1106         if (wpipe->pipe_buffer.size == 0) {
1107                 /*
1108                  * This can only happen for reverse direction use of pipes
1109                  * in a complete OOM situation.
1110                  */
1111                 error = ENOMEM;
1112                 --wpipe->pipe_busy;
1113                 pipeunlock(wpipe);
1114                 PIPE_UNLOCK(wpipe);
1115                 return (error);
1116         }
1117
1118         pipeunlock(wpipe);
1119
1120         orig_resid = uio->uio_resid;
1121
1122         while (uio->uio_resid) {
1123                 int space;
1124
1125                 pipelock(wpipe, 0);
1126                 if (wpipe->pipe_state & PIPE_EOF) {
1127                         pipeunlock(wpipe);
1128                         error = EPIPE;
1129                         break;
1130                 }
1131 #ifndef PIPE_NODIRECT
1132                 /*
1133                  * If the transfer is large, we can gain performance if
1134                  * we do process-to-process copies directly.
1135                  * If the write is non-blocking, we don't use the
1136                  * direct write mechanism.
1137                  *
1138                  * The direct write mechanism will detect the reader going
1139                  * away on us.
1140                  */
1141                 if (uio->uio_segflg == UIO_USERSPACE &&
1142                     uio->uio_iov->iov_len >= PIPE_MINDIRECT &&
1143                     wpipe->pipe_buffer.size >= PIPE_MINDIRECT &&
1144                     (fp->f_flag & FNONBLOCK) == 0) {
1145                         pipeunlock(wpipe);
1146                         error = pipe_direct_write(wpipe, uio);
1147                         if (error)
1148                                 break;
1149                         continue;
1150                 }
1151 #endif
1152
1153                 /*
1154                  * Pipe buffered writes cannot be coincidental with
1155                  * direct writes.  We wait until the currently executing
1156                  * direct write is completed before we start filling the
1157                  * pipe buffer.  We break out if a signal occurs or the
1158                  * reader goes away.
1159                  */
1160                 if (wpipe->pipe_state & PIPE_DIRECTW) {
1161                         if (wpipe->pipe_state & PIPE_WANTR) {
1162                                 wpipe->pipe_state &= ~PIPE_WANTR;
1163                                 wakeup(wpipe);
1164                         }
1165                         pipeselwakeup(wpipe);
1166                         wpipe->pipe_state |= PIPE_WANTW;
1167                         pipeunlock(wpipe);
1168                         error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH,
1169                             "pipbww", 0);
1170                         if (error)
1171                                 break;
1172                         else
1173                                 continue;
1174                 }
1175
1176                 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1177
1178                 /* Writes of size <= PIPE_BUF must be atomic. */
1179                 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
1180                         space = 0;
1181
1182                 if (space > 0) {
1183                         int size;       /* Transfer size */
1184                         int segsize;    /* first segment to transfer */
1185
1186                         /*
1187                          * Transfer size is minimum of uio transfer
1188                          * and free space in pipe buffer.
1189                          */
1190                         if (space > uio->uio_resid)
1191                                 size = uio->uio_resid;
1192                         else
1193                                 size = space;
1194                         /*
1195                          * First segment to transfer is minimum of
1196                          * transfer size and contiguous space in
1197                          * pipe buffer.  If first segment to transfer
1198                          * is less than the transfer size, we've got
1199                          * a wraparound in the buffer.
1200                          */
1201                         segsize = wpipe->pipe_buffer.size -
1202                                 wpipe->pipe_buffer.in;
1203                         if (segsize > size)
1204                                 segsize = size;
1205
1206                         /* Transfer first segment */
1207
1208                         PIPE_UNLOCK(rpipe);
1209                         error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
1210                                         segsize, uio);
1211                         PIPE_LOCK(rpipe);
1212
1213                         if (error == 0 && segsize < size) {
1214                                 KASSERT(wpipe->pipe_buffer.in + segsize ==
1215                                         wpipe->pipe_buffer.size,
1216                                         ("Pipe buffer wraparound disappeared"));
1217                                 /*
1218                                  * Transfer remaining part now, to
1219                                  * support atomic writes.  Wraparound
1220                                  * happened.
1221                                  */
1222
1223                                 PIPE_UNLOCK(rpipe);
1224                                 error = uiomove(
1225                                     &wpipe->pipe_buffer.buffer[0],
1226                                     size - segsize, uio);
1227                                 PIPE_LOCK(rpipe);
1228                         }
1229                         if (error == 0) {
1230                                 wpipe->pipe_buffer.in += size;
1231                                 if (wpipe->pipe_buffer.in >=
1232                                     wpipe->pipe_buffer.size) {
1233                                         KASSERT(wpipe->pipe_buffer.in ==
1234                                                 size - segsize +
1235                                                 wpipe->pipe_buffer.size,
1236                                                 ("Expected wraparound bad"));
1237                                         wpipe->pipe_buffer.in = size - segsize;
1238                                 }
1239
1240                                 wpipe->pipe_buffer.cnt += size;
1241                                 KASSERT(wpipe->pipe_buffer.cnt <=
1242                                         wpipe->pipe_buffer.size,
1243                                         ("Pipe buffer overflow"));
1244                         }
1245                         pipeunlock(wpipe);
1246                         if (error != 0)
1247                                 break;
1248                 } else {
1249                         /*
1250                          * If the "read-side" has been blocked, wake it up now.
1251                          */
1252                         if (wpipe->pipe_state & PIPE_WANTR) {
1253                                 wpipe->pipe_state &= ~PIPE_WANTR;
1254                                 wakeup(wpipe);
1255                         }
1256
1257                         /*
1258                          * don't block on non-blocking I/O
1259                          */
1260                         if (fp->f_flag & FNONBLOCK) {
1261                                 error = EAGAIN;
1262                                 pipeunlock(wpipe);
1263                                 break;
1264                         }
1265
1266                         /*
1267                          * We have no more space and have something to offer,
1268                          * wake up select/poll.
1269                          */
1270                         pipeselwakeup(wpipe);
1271
1272                         wpipe->pipe_state |= PIPE_WANTW;
1273                         pipeunlock(wpipe);
1274                         error = msleep(wpipe, PIPE_MTX(rpipe),
1275                             PRIBIO | PCATCH, "pipewr", 0);
1276                         if (error != 0)
1277                                 break;
1278                 }
1279         }
1280
1281         pipelock(wpipe, 0);
1282         --wpipe->pipe_busy;
1283
1284         if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1285                 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1286                 wakeup(wpipe);
1287         } else if (wpipe->pipe_buffer.cnt > 0) {
1288                 /*
1289                  * If we have put any characters in the buffer, we wake up
1290                  * the reader.
1291                  */
1292                 if (wpipe->pipe_state & PIPE_WANTR) {
1293                         wpipe->pipe_state &= ~PIPE_WANTR;
1294                         wakeup(wpipe);
1295                 }
1296         }
1297
1298         /*
1299          * Don't return EPIPE if any byte was written.
1300          * EINTR and other interrupts are handled by generic I/O layer.
1301          * Do not pretend that I/O succeeded for obvious user error
1302          * like EFAULT.
1303          */
1304         if (uio->uio_resid != orig_resid && error == EPIPE)
1305                 error = 0;
1306
1307         if (error == 0)
1308                 vfs_timestamp(&wpipe->pipe_mtime);
1309
1310         /*
1311          * We have something to offer,
1312          * wake up select/poll.
1313          */
1314         if (wpipe->pipe_buffer.cnt)
1315                 pipeselwakeup(wpipe);
1316
1317         pipeunlock(wpipe);
1318         PIPE_UNLOCK(rpipe);
1319         return (error);
1320 }
1321
1322 /* ARGSUSED */
1323 static int
1324 pipe_truncate(fp, length, active_cred, td)
1325         struct file *fp;
1326         off_t length;
1327         struct ucred *active_cred;
1328         struct thread *td;
1329 {
1330         struct pipe *cpipe;
1331         int error;
1332
1333         cpipe = fp->f_data;
1334         if (cpipe->pipe_state & PIPE_NAMED)
1335                 error = vnops.fo_truncate(fp, length, active_cred, td);
1336         else
1337                 error = invfo_truncate(fp, length, active_cred, td);
1338         return (error);
1339 }
1340
1341 /*
1342  * we implement a very minimal set of ioctls for compatibility with sockets.
1343  */
1344 static int
1345 pipe_ioctl(fp, cmd, data, active_cred, td)
1346         struct file *fp;
1347         u_long cmd;
1348         void *data;
1349         struct ucred *active_cred;
1350         struct thread *td;
1351 {
1352         struct pipe *mpipe = fp->f_data;
1353         int error;
1354
1355         PIPE_LOCK(mpipe);
1356
1357 #ifdef MAC
1358         error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data);
1359         if (error) {
1360                 PIPE_UNLOCK(mpipe);
1361                 return (error);
1362         }
1363 #endif
1364
1365         error = 0;
1366         switch (cmd) {
1367
1368         case FIONBIO:
1369                 break;
1370
1371         case FIOASYNC:
1372                 if (*(int *)data) {
1373                         mpipe->pipe_state |= PIPE_ASYNC;
1374                 } else {
1375                         mpipe->pipe_state &= ~PIPE_ASYNC;
1376                 }
1377                 break;
1378
1379         case FIONREAD:
1380                 if (!(fp->f_flag & FREAD)) {
1381                         *(int *)data = 0;
1382                         PIPE_UNLOCK(mpipe);
1383                         return (0);
1384                 }
1385                 if (mpipe->pipe_state & PIPE_DIRECTW)
1386                         *(int *)data = mpipe->pipe_map.cnt;
1387                 else
1388                         *(int *)data = mpipe->pipe_buffer.cnt;
1389                 break;
1390
1391         case FIOSETOWN:
1392                 PIPE_UNLOCK(mpipe);
1393                 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
1394                 goto out_unlocked;
1395
1396         case FIOGETOWN:
1397                 *(int *)data = fgetown(&mpipe->pipe_sigio);
1398                 break;
1399
1400         /* This is deprecated, FIOSETOWN should be used instead. */
1401         case TIOCSPGRP:
1402                 PIPE_UNLOCK(mpipe);
1403                 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
1404                 goto out_unlocked;
1405
1406         /* This is deprecated, FIOGETOWN should be used instead. */
1407         case TIOCGPGRP:
1408                 *(int *)data = -fgetown(&mpipe->pipe_sigio);
1409                 break;
1410
1411         default:
1412                 error = ENOTTY;
1413                 break;
1414         }
1415         PIPE_UNLOCK(mpipe);
1416 out_unlocked:
1417         return (error);
1418 }
1419
1420 static int
1421 pipe_poll(fp, events, active_cred, td)
1422         struct file *fp;
1423         int events;
1424         struct ucred *active_cred;
1425         struct thread *td;
1426 {
1427         struct pipe *rpipe;
1428         struct pipe *wpipe;
1429         int levents, revents;
1430 #ifdef MAC
1431         int error;
1432 #endif
1433
1434         revents = 0;
1435         rpipe = fp->f_data;
1436         wpipe = PIPE_PEER(rpipe);
1437         PIPE_LOCK(rpipe);
1438 #ifdef MAC
1439         error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair);
1440         if (error)
1441                 goto locked_error;
1442 #endif
1443         if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM))
1444                 if ((rpipe->pipe_state & PIPE_DIRECTW) ||
1445                     (rpipe->pipe_buffer.cnt > 0))
1446                         revents |= events & (POLLIN | POLLRDNORM);
1447
1448         if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM))
1449                 if (wpipe->pipe_present != PIPE_ACTIVE ||
1450                     (wpipe->pipe_state & PIPE_EOF) ||
1451                     (((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
1452                      ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF ||
1453                          wpipe->pipe_buffer.size == 0)))
1454                         revents |= events & (POLLOUT | POLLWRNORM);
1455
1456         levents = events &
1457             (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND);
1458         if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents &&
1459             fp->f_seqcount == rpipe->pipe_wgen)
1460                 events |= POLLINIGNEOF;
1461
1462         if ((events & POLLINIGNEOF) == 0) {
1463                 if (rpipe->pipe_state & PIPE_EOF) {
1464                         revents |= (events & (POLLIN | POLLRDNORM));
1465                         if (wpipe->pipe_present != PIPE_ACTIVE ||
1466                             (wpipe->pipe_state & PIPE_EOF))
1467                                 revents |= POLLHUP;
1468                 }
1469         }
1470
1471         if (revents == 0) {
1472                 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) {
1473                         selrecord(td, &rpipe->pipe_sel);
1474                         if (SEL_WAITING(&rpipe->pipe_sel))
1475                                 rpipe->pipe_state |= PIPE_SEL;
1476                 }
1477
1478                 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) {
1479                         selrecord(td, &wpipe->pipe_sel);
1480                         if (SEL_WAITING(&wpipe->pipe_sel))
1481                                 wpipe->pipe_state |= PIPE_SEL;
1482                 }
1483         }
1484 #ifdef MAC
1485 locked_error:
1486 #endif
1487         PIPE_UNLOCK(rpipe);
1488
1489         return (revents);
1490 }
1491
1492 /*
1493  * We shouldn't need locks here as we're doing a read and this should
1494  * be a natural race.
1495  */
1496 static int
1497 pipe_stat(fp, ub, active_cred, td)
1498         struct file *fp;
1499         struct stat *ub;
1500         struct ucred *active_cred;
1501         struct thread *td;
1502 {
1503         struct pipe *pipe;
1504         int new_unr;
1505 #ifdef MAC
1506         int error;
1507 #endif
1508
1509         pipe = fp->f_data;
1510         PIPE_LOCK(pipe);
1511 #ifdef MAC
1512         error = mac_pipe_check_stat(active_cred, pipe->pipe_pair);
1513         if (error) {
1514                 PIPE_UNLOCK(pipe);
1515                 return (error);
1516         }
1517 #endif
1518
1519         /* For named pipes ask the underlying filesystem. */
1520         if (pipe->pipe_state & PIPE_NAMED) {
1521                 PIPE_UNLOCK(pipe);
1522                 return (vnops.fo_stat(fp, ub, active_cred, td));
1523         }
1524
1525         /*
1526          * Lazily allocate an inode number for the pipe.  Most pipe
1527          * users do not call fstat(2) on the pipe, which means that
1528          * postponing the inode allocation until it is must be
1529          * returned to userland is useful.  If alloc_unr failed,
1530          * assign st_ino zero instead of returning an error.
1531          * Special pipe_ino values:
1532          *  -1 - not yet initialized;
1533          *  0  - alloc_unr failed, return 0 as st_ino forever.
1534          */
1535         if (pipe->pipe_ino == (ino_t)-1) {
1536                 new_unr = alloc_unr(pipeino_unr);
1537                 if (new_unr != -1)
1538                         pipe->pipe_ino = new_unr;
1539                 else
1540                         pipe->pipe_ino = 0;
1541         }
1542         PIPE_UNLOCK(pipe);
1543
1544         bzero(ub, sizeof(*ub));
1545         ub->st_mode = S_IFIFO;
1546         ub->st_blksize = PAGE_SIZE;
1547         if (pipe->pipe_state & PIPE_DIRECTW)
1548                 ub->st_size = pipe->pipe_map.cnt;
1549         else
1550                 ub->st_size = pipe->pipe_buffer.cnt;
1551         ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
1552         ub->st_atim = pipe->pipe_atime;
1553         ub->st_mtim = pipe->pipe_mtime;
1554         ub->st_ctim = pipe->pipe_ctime;
1555         ub->st_uid = fp->f_cred->cr_uid;
1556         ub->st_gid = fp->f_cred->cr_gid;
1557         ub->st_dev = pipedev_ino;
1558         ub->st_ino = pipe->pipe_ino;
1559         /*
1560          * Left as 0: st_nlink, st_rdev, st_flags, st_gen.
1561          */
1562         return (0);
1563 }
1564
1565 /* ARGSUSED */
1566 static int
1567 pipe_close(fp, td)
1568         struct file *fp;
1569         struct thread *td;
1570 {
1571
1572         if (fp->f_vnode != NULL)
1573                 return vnops.fo_close(fp, td);
1574         fp->f_ops = &badfileops;
1575         pipe_dtor(fp->f_data);
1576         fp->f_data = NULL;
1577         return (0);
1578 }
1579
1580 static int
1581 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td)
1582 {
1583         struct pipe *cpipe;
1584         int error;
1585
1586         cpipe = fp->f_data;
1587         if (cpipe->pipe_state & PIPE_NAMED)
1588                 error = vn_chmod(fp, mode, active_cred, td);
1589         else
1590                 error = invfo_chmod(fp, mode, active_cred, td);
1591         return (error);
1592 }
1593
1594 static int
1595 pipe_chown(fp, uid, gid, active_cred, td)
1596         struct file *fp;
1597         uid_t uid;
1598         gid_t gid;
1599         struct ucred *active_cred;
1600         struct thread *td;
1601 {
1602         struct pipe *cpipe;
1603         int error;
1604
1605         cpipe = fp->f_data;
1606         if (cpipe->pipe_state & PIPE_NAMED)
1607                 error = vn_chown(fp, uid, gid, active_cred, td);
1608         else
1609                 error = invfo_chown(fp, uid, gid, active_cred, td);
1610         return (error);
1611 }
1612
1613 static int
1614 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
1615 {
1616         struct pipe *pi;
1617
1618         if (fp->f_type == DTYPE_FIFO)
1619                 return (vn_fill_kinfo(fp, kif, fdp));
1620         kif->kf_type = KF_TYPE_PIPE;
1621         pi = fp->f_data;
1622         kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi;
1623         kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer;
1624         kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt;
1625         return (0);
1626 }
1627
1628 static void
1629 pipe_free_kmem(cpipe)
1630         struct pipe *cpipe;
1631 {
1632
1633         KASSERT(!mtx_owned(PIPE_MTX(cpipe)),
1634             ("pipe_free_kmem: pipe mutex locked"));
1635
1636         if (cpipe->pipe_buffer.buffer != NULL) {
1637                 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size);
1638                 vm_map_remove(pipe_map,
1639                     (vm_offset_t)cpipe->pipe_buffer.buffer,
1640                     (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size);
1641                 cpipe->pipe_buffer.buffer = NULL;
1642         }
1643 #ifndef PIPE_NODIRECT
1644         {
1645                 cpipe->pipe_map.cnt = 0;
1646                 cpipe->pipe_map.pos = 0;
1647                 cpipe->pipe_map.npages = 0;
1648         }
1649 #endif
1650 }
1651
1652 /*
1653  * shutdown the pipe
1654  */
1655 static void
1656 pipeclose(cpipe)
1657         struct pipe *cpipe;
1658 {
1659         struct pipepair *pp;
1660         struct pipe *ppipe;
1661
1662         KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL"));
1663
1664         PIPE_LOCK(cpipe);
1665         pipelock(cpipe, 0);
1666         pp = cpipe->pipe_pair;
1667
1668         pipeselwakeup(cpipe);
1669
1670         /*
1671          * If the other side is blocked, wake it up saying that
1672          * we want to close it down.
1673          */
1674         cpipe->pipe_state |= PIPE_EOF;
1675         while (cpipe->pipe_busy) {
1676                 wakeup(cpipe);
1677                 cpipe->pipe_state |= PIPE_WANT;
1678                 pipeunlock(cpipe);
1679                 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
1680                 pipelock(cpipe, 0);
1681         }
1682
1683
1684         /*
1685          * Disconnect from peer, if any.
1686          */
1687         ppipe = cpipe->pipe_peer;
1688         if (ppipe->pipe_present == PIPE_ACTIVE) {
1689                 pipeselwakeup(ppipe);
1690
1691                 ppipe->pipe_state |= PIPE_EOF;
1692                 wakeup(ppipe);
1693                 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0);
1694         }
1695
1696         /*
1697          * Mark this endpoint as free.  Release kmem resources.  We
1698          * don't mark this endpoint as unused until we've finished
1699          * doing that, or the pipe might disappear out from under
1700          * us.
1701          */
1702         PIPE_UNLOCK(cpipe);
1703         pipe_free_kmem(cpipe);
1704         PIPE_LOCK(cpipe);
1705         cpipe->pipe_present = PIPE_CLOSING;
1706         pipeunlock(cpipe);
1707
1708         /*
1709          * knlist_clear() may sleep dropping the PIPE_MTX. Set the
1710          * PIPE_FINALIZED, that allows other end to free the
1711          * pipe_pair, only after the knotes are completely dismantled.
1712          */
1713         knlist_clear(&cpipe->pipe_sel.si_note, 1);
1714         cpipe->pipe_present = PIPE_FINALIZED;
1715         seldrain(&cpipe->pipe_sel);
1716         knlist_destroy(&cpipe->pipe_sel.si_note);
1717
1718         /*
1719          * If both endpoints are now closed, release the memory for the
1720          * pipe pair.  If not, unlock.
1721          */
1722         if (ppipe->pipe_present == PIPE_FINALIZED) {
1723                 PIPE_UNLOCK(cpipe);
1724 #ifdef MAC
1725                 mac_pipe_destroy(pp);
1726 #endif
1727                 uma_zfree(pipe_zone, cpipe->pipe_pair);
1728         } else
1729                 PIPE_UNLOCK(cpipe);
1730 }
1731
1732 /*ARGSUSED*/
1733 static int
1734 pipe_kqfilter(struct file *fp, struct knote *kn)
1735 {
1736         struct pipe *cpipe;
1737
1738         /*
1739          * If a filter is requested that is not supported by this file
1740          * descriptor, don't return an error, but also don't ever generate an
1741          * event.
1742          */
1743         if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) {
1744                 kn->kn_fop = &pipe_nfiltops;
1745                 return (0);
1746         }
1747         if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) {
1748                 kn->kn_fop = &pipe_nfiltops;
1749                 return (0);
1750         }
1751         cpipe = fp->f_data;
1752         PIPE_LOCK(cpipe);
1753         switch (kn->kn_filter) {
1754         case EVFILT_READ:
1755                 kn->kn_fop = &pipe_rfiltops;
1756                 break;
1757         case EVFILT_WRITE:
1758                 kn->kn_fop = &pipe_wfiltops;
1759                 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) {
1760                         /* other end of pipe has been closed */
1761                         PIPE_UNLOCK(cpipe);
1762                         return (EPIPE);
1763                 }
1764                 cpipe = PIPE_PEER(cpipe);
1765                 break;
1766         default:
1767                 PIPE_UNLOCK(cpipe);
1768                 return (EINVAL);
1769         }
1770
1771         kn->kn_hook = cpipe;
1772         knlist_add(&cpipe->pipe_sel.si_note, kn, 1);
1773         PIPE_UNLOCK(cpipe);
1774         return (0);
1775 }
1776
1777 static void
1778 filt_pipedetach(struct knote *kn)
1779 {
1780         struct pipe *cpipe = kn->kn_hook;
1781
1782         PIPE_LOCK(cpipe);
1783         knlist_remove(&cpipe->pipe_sel.si_note, kn, 1);
1784         PIPE_UNLOCK(cpipe);
1785 }
1786
1787 /*ARGSUSED*/
1788 static int
1789 filt_piperead(struct knote *kn, long hint)
1790 {
1791         struct pipe *rpipe = kn->kn_hook;
1792         struct pipe *wpipe = rpipe->pipe_peer;
1793         int ret;
1794
1795         PIPE_LOCK(rpipe);
1796         kn->kn_data = rpipe->pipe_buffer.cnt;
1797         if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
1798                 kn->kn_data = rpipe->pipe_map.cnt;
1799
1800         if ((rpipe->pipe_state & PIPE_EOF) ||
1801             wpipe->pipe_present != PIPE_ACTIVE ||
1802             (wpipe->pipe_state & PIPE_EOF)) {
1803                 kn->kn_flags |= EV_EOF;
1804                 PIPE_UNLOCK(rpipe);
1805                 return (1);
1806         }
1807         ret = kn->kn_data > 0;
1808         PIPE_UNLOCK(rpipe);
1809         return ret;
1810 }
1811
1812 /*ARGSUSED*/
1813 static int
1814 filt_pipewrite(struct knote *kn, long hint)
1815 {
1816         struct pipe *wpipe;
1817
1818         wpipe = kn->kn_hook;
1819         PIPE_LOCK(wpipe);
1820         if (wpipe->pipe_present != PIPE_ACTIVE ||
1821             (wpipe->pipe_state & PIPE_EOF)) {
1822                 kn->kn_data = 0;
1823                 kn->kn_flags |= EV_EOF;
1824                 PIPE_UNLOCK(wpipe);
1825                 return (1);
1826         }
1827         kn->kn_data = (wpipe->pipe_buffer.size > 0) ?
1828             (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF;
1829         if (wpipe->pipe_state & PIPE_DIRECTW)
1830                 kn->kn_data = 0;
1831
1832         PIPE_UNLOCK(wpipe);
1833         return (kn->kn_data >= PIPE_BUF);
1834 }
1835
1836 static void
1837 filt_pipedetach_notsup(struct knote *kn)
1838 {
1839
1840 }
1841
1842 static int
1843 filt_pipenotsup(struct knote *kn, long hint)
1844 {
1845
1846         return (0);
1847 }