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 ino_t ino; 383 384 ino = dpipe->pipe_ino; 385 peer = (dpipe->pipe_state & PIPE_NAMED) != 0 ? dpipe->pipe_peer : NULL; 386 funsetown(&dpipe->pipe_sigio); 387 pipeclose(dpipe); 388 if (peer != NULL) { 389 funsetown(&peer->pipe_sigio); 390 pipeclose(peer); 391 } 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], int flags, struct filecaps *fcaps1, 400 struct filecaps *fcaps2) 401 { 402 struct file *rf, *wf; 403 struct pipe *rpipe, *wpipe; 404 struct pipepair *pp; 405 int fd, fflags, error; 406 407 pipe_paircreate(td, &pp); 408 rpipe = &pp->pp_rpipe; 409 wpipe = &pp->pp_wpipe; 410 error = falloc_caps(td, &rf, &fd, flags, fcaps1); 411 if (error) { 412 pipeclose(rpipe); 413 pipeclose(wpipe); 414 return (error); 415 } 416 /* An extra reference on `rf' has been held for us by falloc_caps(). */ 417 fildes[0] = fd; 418 419 fflags = FREAD | FWRITE; 420 if ((flags & O_NONBLOCK) != 0) 421 fflags |= FNONBLOCK; 422 423 /* 424 * Warning: once we've gotten past allocation of the fd for the 425 * read-side, we can only drop the read side via fdrop() in order 426 * to avoid races against processes which manage to dup() the read 427 * side while we are blocked trying to allocate the write side. 428 */ 429 finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops); 430 error = falloc_caps(td, &wf, &fd, flags, fcaps2); 431 if (error) { 432 fdclose(td, rf, fildes[0]); 433 fdrop(rf, td); 434 /* rpipe has been closed by fdrop(). */ 435 pipeclose(wpipe); 436 return (error); 437 } 438 /* An extra reference on `wf' has been held for us by falloc_caps(). */ 439 finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops); 440 fdrop(wf, td); 441 fildes[1] = fd; 442 fdrop(rf, td); 443 444 return (0); 445 } 446 447 #ifdef COMPAT_FREEBSD10 448 /* ARGSUSED */ 449 int 450 freebsd10_pipe(struct thread *td, struct freebsd10_pipe_args *uap __unused) 451 { 452 int error; 453 int fildes[2]; 454 455 error = kern_pipe(td, fildes, 0, NULL, NULL); 456 if (error) 457 return (error); 458 459 td->td_retval[0] = fildes[0]; 460 td->td_retval[1] = fildes[1]; 461 462 return (0); 463 } 464 #endif 465 466 int 467 sys_pipe2(struct thread *td, struct pipe2_args *uap) 468 { 469 int error, fildes[2]; 470 471 if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK)) 472 return (EINVAL); 473 error = kern_pipe(td, fildes, uap->flags, NULL, NULL); 474 if (error) 475 return (error); 476 error = copyout(fildes, uap->fildes, 2 * sizeof(int)); 477 if (error) { 478 (void)kern_close(td, fildes[0]); 479 (void)kern_close(td, fildes[1]); 480 } 481 return (error); 482 } 483 484 /* 485 * Allocate kva for pipe circular buffer, the space is pageable 486 * This routine will 'realloc' the size of a pipe safely, if it fails 487 * it will retain the old buffer. 488 * If it fails it will return ENOMEM. 489 */ 490 static int 491 pipespace_new(struct pipe *cpipe, int size) 492 { 493 caddr_t buffer; 494 int error, cnt, firstseg; 495 static int curfail = 0; 496 static struct timeval lastfail; 497 498 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked")); 499 KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW), 500 ("pipespace: resize of direct writes not allowed")); 501 retry: 502 cnt = cpipe->pipe_buffer.cnt; 503 if (cnt > size) 504 size = cnt; 505 506 size = round_page(size); 507 buffer = (caddr_t) vm_map_min(pipe_map); 508 509 error = vm_map_find(pipe_map, NULL, 0, (vm_offset_t *)&buffer, size, 0, 510 VMFS_ANY_SPACE, VM_PROT_RW, VM_PROT_RW, 0); 511 if (error != KERN_SUCCESS) { 512 if ((cpipe->pipe_buffer.buffer == NULL) && 513 (size > SMALL_PIPE_SIZE)) { 514 size = SMALL_PIPE_SIZE; 515 pipefragretry++; 516 goto retry; 517 } 518 if (cpipe->pipe_buffer.buffer == NULL) { 519 pipeallocfail++; 520 if (ppsratecheck(&lastfail, &curfail, 1)) 521 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n"); 522 } else { 523 piperesizefail++; 524 } 525 return (ENOMEM); 526 } 527 528 /* copy data, then free old resources if we're resizing */ 529 if (cnt > 0) { 530 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) { 531 firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out; 532 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 533 buffer, firstseg); 534 if ((cnt - firstseg) > 0) 535 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg], 536 cpipe->pipe_buffer.in); 537 } else { 538 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 539 buffer, cnt); 540 } 541 } 542 pipe_free_kmem(cpipe); 543 cpipe->pipe_buffer.buffer = buffer; 544 cpipe->pipe_buffer.size = size; 545 cpipe->pipe_buffer.in = cnt; 546 cpipe->pipe_buffer.out = 0; 547 cpipe->pipe_buffer.cnt = cnt; 548 atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size); 549 return (0); 550 } 551 552 /* 553 * Wrapper for pipespace_new() that performs locking assertions. 554 */ 555 static int 556 pipespace(struct pipe *cpipe, int size) 557 { 558 559 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 560 ("Unlocked pipe passed to pipespace")); 561 return (pipespace_new(cpipe, size)); 562 } 563 564 /* 565 * lock a pipe for I/O, blocking other access 566 */ 567 static __inline int 568 pipelock(struct pipe *cpipe, int catch) 569 { 570 int error; 571 572 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 573 while (cpipe->pipe_state & PIPE_LOCKFL) { 574 cpipe->pipe_state |= PIPE_LWANT; 575 error = msleep(cpipe, PIPE_MTX(cpipe), 576 catch ? (PRIBIO | PCATCH) : PRIBIO, 577 "pipelk", 0); 578 if (error != 0) 579 return (error); 580 } 581 cpipe->pipe_state |= PIPE_LOCKFL; 582 return (0); 583 } 584 585 /* 586 * unlock a pipe I/O lock 587 */ 588 static __inline void 589 pipeunlock(struct pipe *cpipe) 590 { 591 592 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 593 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 594 ("Unlocked pipe passed to pipeunlock")); 595 cpipe->pipe_state &= ~PIPE_LOCKFL; 596 if (cpipe->pipe_state & PIPE_LWANT) { 597 cpipe->pipe_state &= ~PIPE_LWANT; 598 wakeup(cpipe); 599 } 600 } 601 602 void 603 pipeselwakeup(struct pipe *cpipe) 604 { 605 606 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 607 if (cpipe->pipe_state & PIPE_SEL) { 608 selwakeuppri(&cpipe->pipe_sel, PSOCK); 609 if (!SEL_WAITING(&cpipe->pipe_sel)) 610 cpipe->pipe_state &= ~PIPE_SEL; 611 } 612 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) 613 pgsigio(&cpipe->pipe_sigio, SIGIO, 0); 614 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0); 615 } 616 617 /* 618 * Initialize and allocate VM and memory for pipe. The structure 619 * will start out zero'd from the ctor, so we just manage the kmem. 620 */ 621 static void 622 pipe_create(struct pipe *pipe, int backing) 623 { 624 625 if (backing) { 626 /* 627 * Note that these functions can fail if pipe map is exhausted 628 * (as a result of too many pipes created), but we ignore the 629 * error as it is not fatal and could be provoked by 630 * unprivileged users. The only consequence is worse performance 631 * with given pipe. 632 */ 633 if (amountpipekva > maxpipekva / 2) 634 (void)pipespace_new(pipe, SMALL_PIPE_SIZE); 635 else 636 (void)pipespace_new(pipe, PIPE_SIZE); 637 } 638 639 pipe->pipe_ino = alloc_unr64(&pipeino_unr); 640 } 641 642 /* ARGSUSED */ 643 static int 644 pipe_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 645 int flags, struct thread *td) 646 { 647 struct pipe *rpipe; 648 int error; 649 int nread = 0; 650 int size; 651 652 rpipe = fp->f_data; 653 PIPE_LOCK(rpipe); 654 ++rpipe->pipe_busy; 655 error = pipelock(rpipe, 1); 656 if (error) 657 goto unlocked_error; 658 659 #ifdef MAC 660 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair); 661 if (error) 662 goto locked_error; 663 #endif 664 if (amountpipekva > (3 * maxpipekva) / 4) { 665 if (!(rpipe->pipe_state & PIPE_DIRECTW) && 666 (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) && 667 (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) && 668 (piperesizeallowed == 1)) { 669 PIPE_UNLOCK(rpipe); 670 pipespace(rpipe, SMALL_PIPE_SIZE); 671 PIPE_LOCK(rpipe); 672 } 673 } 674 675 while (uio->uio_resid) { 676 /* 677 * normal pipe buffer receive 678 */ 679 if (rpipe->pipe_buffer.cnt > 0) { 680 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 681 if (size > rpipe->pipe_buffer.cnt) 682 size = rpipe->pipe_buffer.cnt; 683 if (size > uio->uio_resid) 684 size = uio->uio_resid; 685 686 PIPE_UNLOCK(rpipe); 687 error = uiomove( 688 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 689 size, uio); 690 PIPE_LOCK(rpipe); 691 if (error) 692 break; 693 694 rpipe->pipe_buffer.out += size; 695 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 696 rpipe->pipe_buffer.out = 0; 697 698 rpipe->pipe_buffer.cnt -= size; 699 700 /* 701 * If there is no more to read in the pipe, reset 702 * its pointers to the beginning. This improves 703 * cache hit stats. 704 */ 705 if (rpipe->pipe_buffer.cnt == 0) { 706 rpipe->pipe_buffer.in = 0; 707 rpipe->pipe_buffer.out = 0; 708 } 709 nread += size; 710 #ifndef PIPE_NODIRECT 711 /* 712 * Direct copy, bypassing a kernel buffer. 713 */ 714 } else if ((size = rpipe->pipe_map.cnt) && 715 (rpipe->pipe_state & PIPE_DIRECTW)) { 716 if (size > uio->uio_resid) 717 size = (u_int) uio->uio_resid; 718 719 PIPE_UNLOCK(rpipe); 720 error = uiomove_fromphys(rpipe->pipe_map.ms, 721 rpipe->pipe_map.pos, size, uio); 722 PIPE_LOCK(rpipe); 723 if (error) 724 break; 725 nread += size; 726 rpipe->pipe_map.pos += size; 727 rpipe->pipe_map.cnt -= size; 728 if (rpipe->pipe_map.cnt == 0) { 729 rpipe->pipe_state &= ~(PIPE_DIRECTW|PIPE_WANTW); 730 wakeup(rpipe); 731 } 732 #endif 733 } else { 734 /* 735 * detect EOF condition 736 * read returns 0 on EOF, no need to set error 737 */ 738 if (rpipe->pipe_state & PIPE_EOF) 739 break; 740 741 /* 742 * If the "write-side" has been blocked, wake it up now. 743 */ 744 if (rpipe->pipe_state & PIPE_WANTW) { 745 rpipe->pipe_state &= ~PIPE_WANTW; 746 wakeup(rpipe); 747 } 748 749 /* 750 * Break if some data was read. 751 */ 752 if (nread > 0) 753 break; 754 755 /* 756 * Unlock the pipe buffer for our remaining processing. 757 * We will either break out with an error or we will 758 * sleep and relock to loop. 759 */ 760 pipeunlock(rpipe); 761 762 /* 763 * Handle non-blocking mode operation or 764 * wait for more data. 765 */ 766 if (fp->f_flag & FNONBLOCK) { 767 error = EAGAIN; 768 } else { 769 rpipe->pipe_state |= PIPE_WANTR; 770 if ((error = msleep(rpipe, PIPE_MTX(rpipe), 771 PRIBIO | PCATCH, 772 "piperd", 0)) == 0) 773 error = pipelock(rpipe, 1); 774 } 775 if (error) 776 goto unlocked_error; 777 } 778 } 779 #ifdef MAC 780 locked_error: 781 #endif 782 pipeunlock(rpipe); 783 784 /* XXX: should probably do this before getting any locks. */ 785 if (error == 0) 786 vfs_timestamp(&rpipe->pipe_atime); 787 unlocked_error: 788 --rpipe->pipe_busy; 789 790 /* 791 * PIPE_WANT processing only makes sense if pipe_busy is 0. 792 */ 793 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 794 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 795 wakeup(rpipe); 796 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 797 /* 798 * Handle write blocking hysteresis. 799 */ 800 if (rpipe->pipe_state & PIPE_WANTW) { 801 rpipe->pipe_state &= ~PIPE_WANTW; 802 wakeup(rpipe); 803 } 804 } 805 806 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF) 807 pipeselwakeup(rpipe); 808 809 PIPE_UNLOCK(rpipe); 810 return (error); 811 } 812 813 #ifndef PIPE_NODIRECT 814 /* 815 * Map the sending processes' buffer into kernel space and wire it. 816 * This is similar to a physical write operation. 817 */ 818 static int 819 pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio) 820 { 821 u_int size; 822 int i; 823 824 PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED); 825 KASSERT(wpipe->pipe_state & PIPE_DIRECTW, 826 ("Clone attempt on non-direct write pipe!")); 827 828 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size) 829 size = wpipe->pipe_buffer.size; 830 else 831 size = uio->uio_iov->iov_len; 832 833 if ((i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 834 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ, 835 wpipe->pipe_map.ms, PIPENPAGES)) < 0) 836 return (EFAULT); 837 838 /* 839 * set up the control block 840 */ 841 wpipe->pipe_map.npages = i; 842 wpipe->pipe_map.pos = 843 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 844 wpipe->pipe_map.cnt = size; 845 846 /* 847 * and update the uio data 848 */ 849 850 uio->uio_iov->iov_len -= size; 851 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size; 852 if (uio->uio_iov->iov_len == 0) 853 uio->uio_iov++; 854 uio->uio_resid -= size; 855 uio->uio_offset += size; 856 return (0); 857 } 858 859 /* 860 * unmap and unwire the process buffer 861 */ 862 static void 863 pipe_destroy_write_buffer(struct pipe *wpipe) 864 { 865 866 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 867 vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages); 868 wpipe->pipe_map.npages = 0; 869 } 870 871 /* 872 * In the case of a signal, the writing process might go away. This 873 * code copies the data into the circular buffer so that the source 874 * pages can be freed without loss of data. 875 */ 876 static void 877 pipe_clone_write_buffer(struct pipe *wpipe) 878 { 879 struct uio uio; 880 struct iovec iov; 881 int size; 882 int pos; 883 884 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 885 size = wpipe->pipe_map.cnt; 886 pos = wpipe->pipe_map.pos; 887 888 wpipe->pipe_buffer.in = size; 889 wpipe->pipe_buffer.out = 0; 890 wpipe->pipe_buffer.cnt = size; 891 wpipe->pipe_state &= ~PIPE_DIRECTW; 892 893 PIPE_UNLOCK(wpipe); 894 iov.iov_base = wpipe->pipe_buffer.buffer; 895 iov.iov_len = size; 896 uio.uio_iov = &iov; 897 uio.uio_iovcnt = 1; 898 uio.uio_offset = 0; 899 uio.uio_resid = size; 900 uio.uio_segflg = UIO_SYSSPACE; 901 uio.uio_rw = UIO_READ; 902 uio.uio_td = curthread; 903 uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio); 904 PIPE_LOCK(wpipe); 905 pipe_destroy_write_buffer(wpipe); 906 } 907 908 /* 909 * This implements the pipe buffer write mechanism. Note that only 910 * a direct write OR a normal pipe write can be pending at any given time. 911 * If there are any characters in the pipe buffer, the direct write will 912 * be deferred until the receiving process grabs all of the bytes from 913 * the pipe buffer. Then the direct mapping write is set-up. 914 */ 915 static int 916 pipe_direct_write(struct pipe *wpipe, struct uio *uio) 917 { 918 int error; 919 920 retry: 921 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 922 error = pipelock(wpipe, 1); 923 if (error != 0) 924 goto error1; 925 if ((wpipe->pipe_state & PIPE_EOF) != 0) { 926 error = EPIPE; 927 pipeunlock(wpipe); 928 goto error1; 929 } 930 while (wpipe->pipe_state & PIPE_DIRECTW) { 931 if (wpipe->pipe_state & PIPE_WANTR) { 932 wpipe->pipe_state &= ~PIPE_WANTR; 933 wakeup(wpipe); 934 } 935 pipeselwakeup(wpipe); 936 wpipe->pipe_state |= PIPE_WANTW; 937 pipeunlock(wpipe); 938 error = msleep(wpipe, PIPE_MTX(wpipe), 939 PRIBIO | PCATCH, "pipdww", 0); 940 if (error) 941 goto error1; 942 else 943 goto retry; 944 } 945 wpipe->pipe_map.cnt = 0; /* transfer not ready yet */ 946 if (wpipe->pipe_buffer.cnt > 0) { 947 if (wpipe->pipe_state & PIPE_WANTR) { 948 wpipe->pipe_state &= ~PIPE_WANTR; 949 wakeup(wpipe); 950 } 951 pipeselwakeup(wpipe); 952 wpipe->pipe_state |= PIPE_WANTW; 953 pipeunlock(wpipe); 954 error = msleep(wpipe, PIPE_MTX(wpipe), 955 PRIBIO | PCATCH, "pipdwc", 0); 956 if (error) 957 goto error1; 958 else 959 goto retry; 960 } 961 962 wpipe->pipe_state |= PIPE_DIRECTW; 963 964 PIPE_UNLOCK(wpipe); 965 error = pipe_build_write_buffer(wpipe, uio); 966 PIPE_LOCK(wpipe); 967 if (error) { 968 wpipe->pipe_state &= ~PIPE_DIRECTW; 969 pipeunlock(wpipe); 970 goto error1; 971 } 972 973 error = 0; 974 while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) { 975 if (wpipe->pipe_state & PIPE_EOF) { 976 pipe_destroy_write_buffer(wpipe); 977 pipeselwakeup(wpipe); 978 pipeunlock(wpipe); 979 error = EPIPE; 980 goto error1; 981 } 982 if (wpipe->pipe_state & PIPE_WANTR) { 983 wpipe->pipe_state &= ~PIPE_WANTR; 984 wakeup(wpipe); 985 } 986 pipeselwakeup(wpipe); 987 wpipe->pipe_state |= PIPE_WANTW; 988 pipeunlock(wpipe); 989 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH, 990 "pipdwt", 0); 991 pipelock(wpipe, 0); 992 } 993 994 if (wpipe->pipe_state & PIPE_EOF) 995 error = EPIPE; 996 if (wpipe->pipe_state & PIPE_DIRECTW) { 997 /* 998 * this bit of trickery substitutes a kernel buffer for 999 * the process that might be going away. 1000 */ 1001 pipe_clone_write_buffer(wpipe); 1002 } else { 1003 pipe_destroy_write_buffer(wpipe); 1004 } 1005 pipeunlock(wpipe); 1006 return (error); 1007 1008 error1: 1009 wakeup(wpipe); 1010 return (error); 1011 } 1012 #endif 1013 1014 static int 1015 pipe_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 1016 int flags, struct thread *td) 1017 { 1018 int error = 0; 1019 int desiredsize; 1020 ssize_t orig_resid; 1021 struct pipe *wpipe, *rpipe; 1022 1023 rpipe = fp->f_data; 1024 wpipe = PIPE_PEER(rpipe); 1025 PIPE_LOCK(rpipe); 1026 error = pipelock(wpipe, 1); 1027 if (error) { 1028 PIPE_UNLOCK(rpipe); 1029 return (error); 1030 } 1031 /* 1032 * detect loss of pipe read side, issue SIGPIPE if lost. 1033 */ 1034 if (wpipe->pipe_present != PIPE_ACTIVE || 1035 (wpipe->pipe_state & PIPE_EOF)) { 1036 pipeunlock(wpipe); 1037 PIPE_UNLOCK(rpipe); 1038 return (EPIPE); 1039 } 1040 #ifdef MAC 1041 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair); 1042 if (error) { 1043 pipeunlock(wpipe); 1044 PIPE_UNLOCK(rpipe); 1045 return (error); 1046 } 1047 #endif 1048 ++wpipe->pipe_busy; 1049 1050 /* Choose a larger size if it's advantageous */ 1051 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size); 1052 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) { 1053 if (piperesizeallowed != 1) 1054 break; 1055 if (amountpipekva > maxpipekva / 2) 1056 break; 1057 if (desiredsize == BIG_PIPE_SIZE) 1058 break; 1059 desiredsize = desiredsize * 2; 1060 } 1061 1062 /* Choose a smaller size if we're in a OOM situation */ 1063 if ((amountpipekva > (3 * maxpipekva) / 4) && 1064 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) && 1065 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) && 1066 (piperesizeallowed == 1)) 1067 desiredsize = SMALL_PIPE_SIZE; 1068 1069 /* Resize if the above determined that a new size was necessary */ 1070 if ((desiredsize != wpipe->pipe_buffer.size) && 1071 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) { 1072 PIPE_UNLOCK(wpipe); 1073 pipespace(wpipe, desiredsize); 1074 PIPE_LOCK(wpipe); 1075 } 1076 if (wpipe->pipe_buffer.size == 0) { 1077 /* 1078 * This can only happen for reverse direction use of pipes 1079 * in a complete OOM situation. 1080 */ 1081 error = ENOMEM; 1082 --wpipe->pipe_busy; 1083 pipeunlock(wpipe); 1084 PIPE_UNLOCK(wpipe); 1085 return (error); 1086 } 1087 1088 pipeunlock(wpipe); 1089 1090 orig_resid = uio->uio_resid; 1091 1092 while (uio->uio_resid) { 1093 int space; 1094 1095 pipelock(wpipe, 0); 1096 if (wpipe->pipe_state & PIPE_EOF) { 1097 pipeunlock(wpipe); 1098 error = EPIPE; 1099 break; 1100 } 1101 #ifndef PIPE_NODIRECT 1102 /* 1103 * If the transfer is large, we can gain performance if 1104 * we do process-to-process copies directly. 1105 * If the write is non-blocking, we don't use the 1106 * direct write mechanism. 1107 * 1108 * The direct write mechanism will detect the reader going 1109 * away on us. 1110 */ 1111 if (uio->uio_segflg == UIO_USERSPACE && 1112 uio->uio_iov->iov_len >= PIPE_MINDIRECT && 1113 wpipe->pipe_buffer.size >= PIPE_MINDIRECT && 1114 (fp->f_flag & FNONBLOCK) == 0) { 1115 pipeunlock(wpipe); 1116 error = pipe_direct_write(wpipe, uio); 1117 if (error) 1118 break; 1119 continue; 1120 } 1121 #endif 1122 1123 /* 1124 * Pipe buffered writes cannot be coincidental with 1125 * direct writes. We wait until the currently executing 1126 * direct write is completed before we start filling the 1127 * pipe buffer. We break out if a signal occurs or the 1128 * reader goes away. 1129 */ 1130 if (wpipe->pipe_state & PIPE_DIRECTW) { 1131 if (wpipe->pipe_state & PIPE_WANTR) { 1132 wpipe->pipe_state &= ~PIPE_WANTR; 1133 wakeup(wpipe); 1134 } 1135 pipeselwakeup(wpipe); 1136 wpipe->pipe_state |= PIPE_WANTW; 1137 pipeunlock(wpipe); 1138 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH, 1139 "pipbww", 0); 1140 if (error) 1141 break; 1142 else 1143 continue; 1144 } 1145 1146 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1147 1148 /* Writes of size <= PIPE_BUF must be atomic. */ 1149 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 1150 space = 0; 1151 1152 if (space > 0) { 1153 int size; /* Transfer size */ 1154 int segsize; /* first segment to transfer */ 1155 1156 /* 1157 * Transfer size is minimum of uio transfer 1158 * and free space in pipe buffer. 1159 */ 1160 if (space > uio->uio_resid) 1161 size = uio->uio_resid; 1162 else 1163 size = space; 1164 /* 1165 * First segment to transfer is minimum of 1166 * transfer size and contiguous space in 1167 * pipe buffer. If first segment to transfer 1168 * is less than the transfer size, we've got 1169 * a wraparound in the buffer. 1170 */ 1171 segsize = wpipe->pipe_buffer.size - 1172 wpipe->pipe_buffer.in; 1173 if (segsize > size) 1174 segsize = size; 1175 1176 /* Transfer first segment */ 1177 1178 PIPE_UNLOCK(rpipe); 1179 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 1180 segsize, uio); 1181 PIPE_LOCK(rpipe); 1182 1183 if (error == 0 && segsize < size) { 1184 KASSERT(wpipe->pipe_buffer.in + segsize == 1185 wpipe->pipe_buffer.size, 1186 ("Pipe buffer wraparound disappeared")); 1187 /* 1188 * Transfer remaining part now, to 1189 * support atomic writes. Wraparound 1190 * happened. 1191 */ 1192 1193 PIPE_UNLOCK(rpipe); 1194 error = uiomove( 1195 &wpipe->pipe_buffer.buffer[0], 1196 size - segsize, uio); 1197 PIPE_LOCK(rpipe); 1198 } 1199 if (error == 0) { 1200 wpipe->pipe_buffer.in += size; 1201 if (wpipe->pipe_buffer.in >= 1202 wpipe->pipe_buffer.size) { 1203 KASSERT(wpipe->pipe_buffer.in == 1204 size - segsize + 1205 wpipe->pipe_buffer.size, 1206 ("Expected wraparound bad")); 1207 wpipe->pipe_buffer.in = size - segsize; 1208 } 1209 1210 wpipe->pipe_buffer.cnt += size; 1211 KASSERT(wpipe->pipe_buffer.cnt <= 1212 wpipe->pipe_buffer.size, 1213 ("Pipe buffer overflow")); 1214 } 1215 pipeunlock(wpipe); 1216 if (error != 0) 1217 break; 1218 } else { 1219 /* 1220 * If the "read-side" has been blocked, wake it up now. 1221 */ 1222 if (wpipe->pipe_state & PIPE_WANTR) { 1223 wpipe->pipe_state &= ~PIPE_WANTR; 1224 wakeup(wpipe); 1225 } 1226 1227 /* 1228 * don't block on non-blocking I/O 1229 */ 1230 if (fp->f_flag & FNONBLOCK) { 1231 error = EAGAIN; 1232 pipeunlock(wpipe); 1233 break; 1234 } 1235 1236 /* 1237 * We have no more space and have something to offer, 1238 * wake up select/poll. 1239 */ 1240 pipeselwakeup(wpipe); 1241 1242 wpipe->pipe_state |= PIPE_WANTW; 1243 pipeunlock(wpipe); 1244 error = msleep(wpipe, PIPE_MTX(rpipe), 1245 PRIBIO | PCATCH, "pipewr", 0); 1246 if (error != 0) 1247 break; 1248 } 1249 } 1250 1251 pipelock(wpipe, 0); 1252 --wpipe->pipe_busy; 1253 1254 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 1255 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 1256 wakeup(wpipe); 1257 } else if (wpipe->pipe_buffer.cnt > 0) { 1258 /* 1259 * If we have put any characters in the buffer, we wake up 1260 * the reader. 1261 */ 1262 if (wpipe->pipe_state & PIPE_WANTR) { 1263 wpipe->pipe_state &= ~PIPE_WANTR; 1264 wakeup(wpipe); 1265 } 1266 } 1267 1268 /* 1269 * Don't return EPIPE if any byte was written. 1270 * EINTR and other interrupts are handled by generic I/O layer. 1271 * Do not pretend that I/O succeeded for obvious user error 1272 * like EFAULT. 1273 */ 1274 if (uio->uio_resid != orig_resid && error == EPIPE) 1275 error = 0; 1276 1277 if (error == 0) 1278 vfs_timestamp(&wpipe->pipe_mtime); 1279 1280 /* 1281 * We have something to offer, 1282 * wake up select/poll. 1283 */ 1284 if (wpipe->pipe_buffer.cnt) 1285 pipeselwakeup(wpipe); 1286 1287 pipeunlock(wpipe); 1288 PIPE_UNLOCK(rpipe); 1289 return (error); 1290 } 1291 1292 /* ARGSUSED */ 1293 static int 1294 pipe_truncate(struct file *fp, off_t length, struct ucred *active_cred, 1295 struct thread *td) 1296 { 1297 struct pipe *cpipe; 1298 int error; 1299 1300 cpipe = fp->f_data; 1301 if (cpipe->pipe_state & PIPE_NAMED) 1302 error = vnops.fo_truncate(fp, length, active_cred, td); 1303 else 1304 error = invfo_truncate(fp, length, active_cred, td); 1305 return (error); 1306 } 1307 1308 /* 1309 * we implement a very minimal set of ioctls for compatibility with sockets. 1310 */ 1311 static int 1312 pipe_ioctl(struct file *fp, u_long cmd, void *data, struct ucred *active_cred, 1313 struct thread *td) 1314 { 1315 struct pipe *mpipe = fp->f_data; 1316 int error; 1317 1318 PIPE_LOCK(mpipe); 1319 1320 #ifdef MAC 1321 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data); 1322 if (error) { 1323 PIPE_UNLOCK(mpipe); 1324 return (error); 1325 } 1326 #endif 1327 1328 error = 0; 1329 switch (cmd) { 1330 1331 case FIONBIO: 1332 break; 1333 1334 case FIOASYNC: 1335 if (*(int *)data) { 1336 mpipe->pipe_state |= PIPE_ASYNC; 1337 } else { 1338 mpipe->pipe_state &= ~PIPE_ASYNC; 1339 } 1340 break; 1341 1342 case FIONREAD: 1343 if (!(fp->f_flag & FREAD)) { 1344 *(int *)data = 0; 1345 PIPE_UNLOCK(mpipe); 1346 return (0); 1347 } 1348 if (mpipe->pipe_state & PIPE_DIRECTW) 1349 *(int *)data = mpipe->pipe_map.cnt; 1350 else 1351 *(int *)data = mpipe->pipe_buffer.cnt; 1352 break; 1353 1354 case FIOSETOWN: 1355 PIPE_UNLOCK(mpipe); 1356 error = fsetown(*(int *)data, &mpipe->pipe_sigio); 1357 goto out_unlocked; 1358 1359 case FIOGETOWN: 1360 *(int *)data = fgetown(&mpipe->pipe_sigio); 1361 break; 1362 1363 /* This is deprecated, FIOSETOWN should be used instead. */ 1364 case TIOCSPGRP: 1365 PIPE_UNLOCK(mpipe); 1366 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio); 1367 goto out_unlocked; 1368 1369 /* This is deprecated, FIOGETOWN should be used instead. */ 1370 case TIOCGPGRP: 1371 *(int *)data = -fgetown(&mpipe->pipe_sigio); 1372 break; 1373 1374 default: 1375 error = ENOTTY; 1376 break; 1377 } 1378 PIPE_UNLOCK(mpipe); 1379 out_unlocked: 1380 return (error); 1381 } 1382 1383 static int 1384 pipe_poll(struct file *fp, int events, struct ucred *active_cred, 1385 struct thread *td) 1386 { 1387 struct pipe *rpipe; 1388 struct pipe *wpipe; 1389 int levents, revents; 1390 #ifdef MAC 1391 int error; 1392 #endif 1393 1394 revents = 0; 1395 rpipe = fp->f_data; 1396 wpipe = PIPE_PEER(rpipe); 1397 PIPE_LOCK(rpipe); 1398 #ifdef MAC 1399 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair); 1400 if (error) 1401 goto locked_error; 1402 #endif 1403 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) 1404 if ((rpipe->pipe_state & PIPE_DIRECTW) || 1405 (rpipe->pipe_buffer.cnt > 0)) 1406 revents |= events & (POLLIN | POLLRDNORM); 1407 1408 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) 1409 if (wpipe->pipe_present != PIPE_ACTIVE || 1410 (wpipe->pipe_state & PIPE_EOF) || 1411 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) && 1412 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF || 1413 wpipe->pipe_buffer.size == 0))) 1414 revents |= events & (POLLOUT | POLLWRNORM); 1415 1416 levents = events & 1417 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND); 1418 if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents && 1419 fp->f_seqcount == rpipe->pipe_wgen) 1420 events |= POLLINIGNEOF; 1421 1422 if ((events & POLLINIGNEOF) == 0) { 1423 if (rpipe->pipe_state & PIPE_EOF) { 1424 revents |= (events & (POLLIN | POLLRDNORM)); 1425 if (wpipe->pipe_present != PIPE_ACTIVE || 1426 (wpipe->pipe_state & PIPE_EOF)) 1427 revents |= POLLHUP; 1428 } 1429 } 1430 1431 if (revents == 0) { 1432 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) { 1433 selrecord(td, &rpipe->pipe_sel); 1434 if (SEL_WAITING(&rpipe->pipe_sel)) 1435 rpipe->pipe_state |= PIPE_SEL; 1436 } 1437 1438 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) { 1439 selrecord(td, &wpipe->pipe_sel); 1440 if (SEL_WAITING(&wpipe->pipe_sel)) 1441 wpipe->pipe_state |= PIPE_SEL; 1442 } 1443 } 1444 #ifdef MAC 1445 locked_error: 1446 #endif 1447 PIPE_UNLOCK(rpipe); 1448 1449 return (revents); 1450 } 1451 1452 /* 1453 * We shouldn't need locks here as we're doing a read and this should 1454 * be a natural race. 1455 */ 1456 static int 1457 pipe_stat(struct file *fp, struct stat *ub, struct ucred *active_cred, 1458 struct thread *td) 1459 { 1460 struct pipe *pipe; 1461 #ifdef MAC 1462 int error; 1463 #endif 1464 1465 pipe = fp->f_data; 1466 PIPE_LOCK(pipe); 1467 #ifdef MAC 1468 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair); 1469 if (error) { 1470 PIPE_UNLOCK(pipe); 1471 return (error); 1472 } 1473 #endif 1474 1475 /* For named pipes ask the underlying filesystem. */ 1476 if (pipe->pipe_state & PIPE_NAMED) { 1477 PIPE_UNLOCK(pipe); 1478 return (vnops.fo_stat(fp, ub, active_cred, td)); 1479 } 1480 1481 PIPE_UNLOCK(pipe); 1482 1483 bzero(ub, sizeof(*ub)); 1484 ub->st_mode = S_IFIFO; 1485 ub->st_blksize = PAGE_SIZE; 1486 if (pipe->pipe_state & PIPE_DIRECTW) 1487 ub->st_size = pipe->pipe_map.cnt; 1488 else 1489 ub->st_size = pipe->pipe_buffer.cnt; 1490 ub->st_blocks = howmany(ub->st_size, ub->st_blksize); 1491 ub->st_atim = pipe->pipe_atime; 1492 ub->st_mtim = pipe->pipe_mtime; 1493 ub->st_ctim = pipe->pipe_ctime; 1494 ub->st_uid = fp->f_cred->cr_uid; 1495 ub->st_gid = fp->f_cred->cr_gid; 1496 ub->st_dev = pipedev_ino; 1497 ub->st_ino = pipe->pipe_ino; 1498 /* 1499 * Left as 0: st_nlink, st_rdev, st_flags, st_gen. 1500 */ 1501 return (0); 1502 } 1503 1504 /* ARGSUSED */ 1505 static int 1506 pipe_close(struct file *fp, struct thread *td) 1507 { 1508 1509 if (fp->f_vnode != NULL) 1510 return vnops.fo_close(fp, td); 1511 fp->f_ops = &badfileops; 1512 pipe_dtor(fp->f_data); 1513 fp->f_data = NULL; 1514 return (0); 1515 } 1516 1517 static int 1518 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td) 1519 { 1520 struct pipe *cpipe; 1521 int error; 1522 1523 cpipe = fp->f_data; 1524 if (cpipe->pipe_state & PIPE_NAMED) 1525 error = vn_chmod(fp, mode, active_cred, td); 1526 else 1527 error = invfo_chmod(fp, mode, active_cred, td); 1528 return (error); 1529 } 1530 1531 static int 1532 pipe_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1533 struct thread *td) 1534 { 1535 struct pipe *cpipe; 1536 int error; 1537 1538 cpipe = fp->f_data; 1539 if (cpipe->pipe_state & PIPE_NAMED) 1540 error = vn_chown(fp, uid, gid, active_cred, td); 1541 else 1542 error = invfo_chown(fp, uid, gid, active_cred, td); 1543 return (error); 1544 } 1545 1546 static int 1547 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp) 1548 { 1549 struct pipe *pi; 1550 1551 if (fp->f_type == DTYPE_FIFO) 1552 return (vn_fill_kinfo(fp, kif, fdp)); 1553 kif->kf_type = KF_TYPE_PIPE; 1554 pi = fp->f_data; 1555 kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi; 1556 kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer; 1557 kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt; 1558 return (0); 1559 } 1560 1561 static void 1562 pipe_free_kmem(struct pipe *cpipe) 1563 { 1564 1565 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), 1566 ("pipe_free_kmem: pipe mutex locked")); 1567 1568 if (cpipe->pipe_buffer.buffer != NULL) { 1569 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size); 1570 vm_map_remove(pipe_map, 1571 (vm_offset_t)cpipe->pipe_buffer.buffer, 1572 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size); 1573 cpipe->pipe_buffer.buffer = NULL; 1574 } 1575 #ifndef PIPE_NODIRECT 1576 { 1577 cpipe->pipe_map.cnt = 0; 1578 cpipe->pipe_map.pos = 0; 1579 cpipe->pipe_map.npages = 0; 1580 } 1581 #endif 1582 } 1583 1584 /* 1585 * shutdown the pipe 1586 */ 1587 static void 1588 pipeclose(struct pipe *cpipe) 1589 { 1590 struct pipepair *pp; 1591 struct pipe *ppipe; 1592 1593 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL")); 1594 1595 PIPE_LOCK(cpipe); 1596 pipelock(cpipe, 0); 1597 pp = cpipe->pipe_pair; 1598 1599 pipeselwakeup(cpipe); 1600 1601 /* 1602 * If the other side is blocked, wake it up saying that 1603 * we want to close it down. 1604 */ 1605 cpipe->pipe_state |= PIPE_EOF; 1606 while (cpipe->pipe_busy) { 1607 wakeup(cpipe); 1608 cpipe->pipe_state |= PIPE_WANT; 1609 pipeunlock(cpipe); 1610 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0); 1611 pipelock(cpipe, 0); 1612 } 1613 1614 1615 /* 1616 * Disconnect from peer, if any. 1617 */ 1618 ppipe = cpipe->pipe_peer; 1619 if (ppipe->pipe_present == PIPE_ACTIVE) { 1620 pipeselwakeup(ppipe); 1621 1622 ppipe->pipe_state |= PIPE_EOF; 1623 wakeup(ppipe); 1624 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0); 1625 } 1626 1627 /* 1628 * Mark this endpoint as free. Release kmem resources. We 1629 * don't mark this endpoint as unused until we've finished 1630 * doing that, or the pipe might disappear out from under 1631 * us. 1632 */ 1633 PIPE_UNLOCK(cpipe); 1634 pipe_free_kmem(cpipe); 1635 PIPE_LOCK(cpipe); 1636 cpipe->pipe_present = PIPE_CLOSING; 1637 pipeunlock(cpipe); 1638 1639 /* 1640 * knlist_clear() may sleep dropping the PIPE_MTX. Set the 1641 * PIPE_FINALIZED, that allows other end to free the 1642 * pipe_pair, only after the knotes are completely dismantled. 1643 */ 1644 knlist_clear(&cpipe->pipe_sel.si_note, 1); 1645 cpipe->pipe_present = PIPE_FINALIZED; 1646 seldrain(&cpipe->pipe_sel); 1647 knlist_destroy(&cpipe->pipe_sel.si_note); 1648 1649 /* 1650 * If both endpoints are now closed, release the memory for the 1651 * pipe pair. If not, unlock. 1652 */ 1653 if (ppipe->pipe_present == PIPE_FINALIZED) { 1654 PIPE_UNLOCK(cpipe); 1655 #ifdef MAC 1656 mac_pipe_destroy(pp); 1657 #endif 1658 uma_zfree(pipe_zone, cpipe->pipe_pair); 1659 } else 1660 PIPE_UNLOCK(cpipe); 1661 } 1662 1663 /*ARGSUSED*/ 1664 static int 1665 pipe_kqfilter(struct file *fp, struct knote *kn) 1666 { 1667 struct pipe *cpipe; 1668 1669 /* 1670 * If a filter is requested that is not supported by this file 1671 * descriptor, don't return an error, but also don't ever generate an 1672 * event. 1673 */ 1674 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) { 1675 kn->kn_fop = &pipe_nfiltops; 1676 return (0); 1677 } 1678 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) { 1679 kn->kn_fop = &pipe_nfiltops; 1680 return (0); 1681 } 1682 cpipe = fp->f_data; 1683 PIPE_LOCK(cpipe); 1684 switch (kn->kn_filter) { 1685 case EVFILT_READ: 1686 kn->kn_fop = &pipe_rfiltops; 1687 break; 1688 case EVFILT_WRITE: 1689 kn->kn_fop = &pipe_wfiltops; 1690 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) { 1691 /* other end of pipe has been closed */ 1692 PIPE_UNLOCK(cpipe); 1693 return (EPIPE); 1694 } 1695 cpipe = PIPE_PEER(cpipe); 1696 break; 1697 default: 1698 PIPE_UNLOCK(cpipe); 1699 return (EINVAL); 1700 } 1701 1702 kn->kn_hook = cpipe; 1703 knlist_add(&cpipe->pipe_sel.si_note, kn, 1); 1704 PIPE_UNLOCK(cpipe); 1705 return (0); 1706 } 1707 1708 static void 1709 filt_pipedetach(struct knote *kn) 1710 { 1711 struct pipe *cpipe = kn->kn_hook; 1712 1713 PIPE_LOCK(cpipe); 1714 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1); 1715 PIPE_UNLOCK(cpipe); 1716 } 1717 1718 /*ARGSUSED*/ 1719 static int 1720 filt_piperead(struct knote *kn, long hint) 1721 { 1722 struct pipe *rpipe = kn->kn_hook; 1723 struct pipe *wpipe = rpipe->pipe_peer; 1724 int ret; 1725 1726 PIPE_LOCK_ASSERT(rpipe, MA_OWNED); 1727 kn->kn_data = rpipe->pipe_buffer.cnt; 1728 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) 1729 kn->kn_data = rpipe->pipe_map.cnt; 1730 1731 if ((rpipe->pipe_state & PIPE_EOF) || 1732 wpipe->pipe_present != PIPE_ACTIVE || 1733 (wpipe->pipe_state & PIPE_EOF)) { 1734 kn->kn_flags |= EV_EOF; 1735 return (1); 1736 } 1737 ret = kn->kn_data > 0; 1738 return ret; 1739 } 1740 1741 /*ARGSUSED*/ 1742 static int 1743 filt_pipewrite(struct knote *kn, long hint) 1744 { 1745 struct pipe *wpipe; 1746 1747 wpipe = kn->kn_hook; 1748 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 1749 if (wpipe->pipe_present != PIPE_ACTIVE || 1750 (wpipe->pipe_state & PIPE_EOF)) { 1751 kn->kn_data = 0; 1752 kn->kn_flags |= EV_EOF; 1753 return (1); 1754 } 1755 kn->kn_data = (wpipe->pipe_buffer.size > 0) ? 1756 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF; 1757 if (wpipe->pipe_state & PIPE_DIRECTW) 1758 kn->kn_data = 0; 1759 1760 return (kn->kn_data >= PIPE_BUF); 1761 } 1762 1763 static void 1764 filt_pipedetach_notsup(struct knote *kn) 1765 { 1766 1767 } 1768 1769 static int 1770 filt_pipenotsup(struct knote *kn, long hint) 1771 { 1772 1773 return (0); 1774 } 1775