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_type & PIPE_TYPE_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 static long pipe_mindirect = PIPE_MINDIRECT; 213 214 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, 215 &maxpipekva, 0, "Pipe KVA limit"); 216 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD, 217 &amountpipekva, 0, "Pipe KVA usage"); 218 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD, 219 &pipefragretry, 0, "Pipe allocation retries due to fragmentation"); 220 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD, 221 &pipeallocfail, 0, "Pipe allocation failures"); 222 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD, 223 &piperesizefail, 0, "Pipe resize failures"); 224 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW, 225 &piperesizeallowed, 0, "Pipe resizing allowed"); 226 227 static void pipeinit(void *dummy __unused); 228 static void pipeclose(struct pipe *cpipe); 229 static void pipe_free_kmem(struct pipe *cpipe); 230 static int pipe_create(struct pipe *pipe, bool backing); 231 static int pipe_paircreate(struct thread *td, struct pipepair **p_pp); 232 static __inline int pipelock(struct pipe *cpipe, int catch); 233 static __inline void pipeunlock(struct pipe *cpipe); 234 static void pipe_timestamp(struct timespec *tsp); 235 #ifndef PIPE_NODIRECT 236 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio); 237 static void pipe_destroy_write_buffer(struct pipe *wpipe); 238 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio); 239 static void pipe_clone_write_buffer(struct pipe *wpipe); 240 #endif 241 static int pipespace(struct pipe *cpipe, int size); 242 static int pipespace_new(struct pipe *cpipe, int size); 243 244 static int pipe_zone_ctor(void *mem, int size, void *arg, int flags); 245 static int pipe_zone_init(void *mem, int size, int flags); 246 static void pipe_zone_fini(void *mem, int size); 247 248 static uma_zone_t pipe_zone; 249 static struct unrhdr64 pipeino_unr; 250 static dev_t pipedev_ino; 251 252 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL); 253 254 static void 255 pipeinit(void *dummy __unused) 256 { 257 258 pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair), 259 pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini, 260 UMA_ALIGN_PTR, 0); 261 KASSERT(pipe_zone != NULL, ("pipe_zone not initialized")); 262 new_unrhdr64(&pipeino_unr, 1); 263 pipedev_ino = devfs_alloc_cdp_inode(); 264 KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized")); 265 } 266 267 static int 268 sysctl_handle_pipe_mindirect(SYSCTL_HANDLER_ARGS) 269 { 270 int error = 0; 271 long tmp_pipe_mindirect = pipe_mindirect; 272 273 error = sysctl_handle_long(oidp, &tmp_pipe_mindirect, arg2, req); 274 if (error != 0 || req->newptr == NULL) 275 return (error); 276 277 /* 278 * Don't allow pipe_mindirect to be set so low that we violate 279 * atomicity requirements. 280 */ 281 if (tmp_pipe_mindirect <= PIPE_BUF) 282 return (EINVAL); 283 pipe_mindirect = tmp_pipe_mindirect; 284 return (0); 285 } 286 SYSCTL_OID(_kern_ipc, OID_AUTO, pipe_mindirect, CTLTYPE_LONG | CTLFLAG_RW, 287 &pipe_mindirect, 0, sysctl_handle_pipe_mindirect, "L", 288 "Minimum write size triggering VM optimization"); 289 290 static int 291 pipe_zone_ctor(void *mem, int size, void *arg, int flags) 292 { 293 struct pipepair *pp; 294 struct pipe *rpipe, *wpipe; 295 296 KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size")); 297 298 pp = (struct pipepair *)mem; 299 300 /* 301 * We zero both pipe endpoints to make sure all the kmem pointers 302 * are NULL, flag fields are zero'd, etc. We timestamp both 303 * endpoints with the same time. 304 */ 305 rpipe = &pp->pp_rpipe; 306 bzero(rpipe, sizeof(*rpipe)); 307 pipe_timestamp(&rpipe->pipe_ctime); 308 rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime; 309 310 wpipe = &pp->pp_wpipe; 311 bzero(wpipe, sizeof(*wpipe)); 312 wpipe->pipe_ctime = rpipe->pipe_ctime; 313 wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime; 314 315 rpipe->pipe_peer = wpipe; 316 rpipe->pipe_pair = pp; 317 wpipe->pipe_peer = rpipe; 318 wpipe->pipe_pair = pp; 319 320 /* 321 * Mark both endpoints as present; they will later get free'd 322 * one at a time. When both are free'd, then the whole pair 323 * is released. 324 */ 325 rpipe->pipe_present = PIPE_ACTIVE; 326 wpipe->pipe_present = PIPE_ACTIVE; 327 328 /* 329 * Eventually, the MAC Framework may initialize the label 330 * in ctor or init, but for now we do it elswhere to avoid 331 * blocking in ctor or init. 332 */ 333 pp->pp_label = NULL; 334 335 return (0); 336 } 337 338 static int 339 pipe_zone_init(void *mem, int size, int flags) 340 { 341 struct pipepair *pp; 342 343 KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size")); 344 345 pp = (struct pipepair *)mem; 346 347 mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_NEW); 348 return (0); 349 } 350 351 static void 352 pipe_zone_fini(void *mem, int size) 353 { 354 struct pipepair *pp; 355 356 KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size")); 357 358 pp = (struct pipepair *)mem; 359 360 mtx_destroy(&pp->pp_mtx); 361 } 362 363 static int 364 pipe_paircreate(struct thread *td, struct pipepair **p_pp) 365 { 366 struct pipepair *pp; 367 struct pipe *rpipe, *wpipe; 368 int error; 369 370 *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK); 371 #ifdef MAC 372 /* 373 * The MAC label is shared between the connected endpoints. As a 374 * result mac_pipe_init() and mac_pipe_create() are called once 375 * for the pair, and not on the endpoints. 376 */ 377 mac_pipe_init(pp); 378 mac_pipe_create(td->td_ucred, pp); 379 #endif 380 rpipe = &pp->pp_rpipe; 381 wpipe = &pp->pp_wpipe; 382 383 knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe)); 384 knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe)); 385 386 /* 387 * Only the forward direction pipe is backed by big buffer by 388 * default. 389 */ 390 error = pipe_create(rpipe, true); 391 if (error != 0) 392 goto fail; 393 error = pipe_create(wpipe, false); 394 if (error != 0) { 395 /* 396 * This cleanup leaves the pipe inode number for rpipe 397 * still allocated, but never used. We do not free 398 * inode numbers for opened pipes, which is required 399 * for correctness because numbers must be unique. 400 * But also it avoids any memory use by the unr 401 * allocator, so stashing away the transient inode 402 * number is reasonable. 403 */ 404 pipe_free_kmem(rpipe); 405 goto fail; 406 } 407 408 rpipe->pipe_state |= PIPE_DIRECTOK; 409 wpipe->pipe_state |= PIPE_DIRECTOK; 410 return (0); 411 412 fail: 413 knlist_destroy(&rpipe->pipe_sel.si_note); 414 knlist_destroy(&wpipe->pipe_sel.si_note); 415 #ifdef MAC 416 mac_pipe_destroy(pp); 417 #endif 418 uma_zfree(pipe_zone, pp); 419 return (error); 420 } 421 422 int 423 pipe_named_ctor(struct pipe **ppipe, struct thread *td) 424 { 425 struct pipepair *pp; 426 int error; 427 428 error = pipe_paircreate(td, &pp); 429 if (error != 0) 430 return (error); 431 pp->pp_rpipe.pipe_type |= PIPE_TYPE_NAMED; 432 *ppipe = &pp->pp_rpipe; 433 return (0); 434 } 435 436 void 437 pipe_dtor(struct pipe *dpipe) 438 { 439 struct pipe *peer; 440 441 peer = (dpipe->pipe_type & PIPE_TYPE_NAMED) != 0 ? dpipe->pipe_peer : NULL; 442 funsetown(&dpipe->pipe_sigio); 443 pipeclose(dpipe); 444 if (peer != NULL) { 445 funsetown(&peer->pipe_sigio); 446 pipeclose(peer); 447 } 448 } 449 450 /* 451 * Get a timestamp. 452 * 453 * This used to be vfs_timestamp but the higher precision is unnecessary and 454 * can very negatively affect performance in virtualized environments (e.g., on 455 * vms running on amd64 when using the rdtscp instruction). 456 */ 457 static void 458 pipe_timestamp(struct timespec *tsp) 459 { 460 461 getnanotime(tsp); 462 } 463 464 /* 465 * The pipe system call for the DTYPE_PIPE type of pipes. If we fail, let 466 * the zone pick up the pieces via pipeclose(). 467 */ 468 int 469 kern_pipe(struct thread *td, int fildes[2], int flags, struct filecaps *fcaps1, 470 struct filecaps *fcaps2) 471 { 472 struct file *rf, *wf; 473 struct pipe *rpipe, *wpipe; 474 struct pipepair *pp; 475 int fd, fflags, error; 476 477 error = pipe_paircreate(td, &pp); 478 if (error != 0) 479 return (error); 480 rpipe = &pp->pp_rpipe; 481 wpipe = &pp->pp_wpipe; 482 error = falloc_caps(td, &rf, &fd, flags, fcaps1); 483 if (error) { 484 pipeclose(rpipe); 485 pipeclose(wpipe); 486 return (error); 487 } 488 /* An extra reference on `rf' has been held for us by falloc_caps(). */ 489 fildes[0] = fd; 490 491 fflags = FREAD | FWRITE; 492 if ((flags & O_NONBLOCK) != 0) 493 fflags |= FNONBLOCK; 494 495 /* 496 * Warning: once we've gotten past allocation of the fd for the 497 * read-side, we can only drop the read side via fdrop() in order 498 * to avoid races against processes which manage to dup() the read 499 * side while we are blocked trying to allocate the write side. 500 */ 501 finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops); 502 error = falloc_caps(td, &wf, &fd, flags, fcaps2); 503 if (error) { 504 fdclose(td, rf, fildes[0]); 505 fdrop(rf, td); 506 /* rpipe has been closed by fdrop(). */ 507 pipeclose(wpipe); 508 return (error); 509 } 510 /* An extra reference on `wf' has been held for us by falloc_caps(). */ 511 finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops); 512 fdrop(wf, td); 513 fildes[1] = fd; 514 fdrop(rf, td); 515 516 return (0); 517 } 518 519 #ifdef COMPAT_FREEBSD10 520 /* ARGSUSED */ 521 int 522 freebsd10_pipe(struct thread *td, struct freebsd10_pipe_args *uap __unused) 523 { 524 int error; 525 int fildes[2]; 526 527 error = kern_pipe(td, fildes, 0, NULL, NULL); 528 if (error) 529 return (error); 530 531 td->td_retval[0] = fildes[0]; 532 td->td_retval[1] = fildes[1]; 533 534 return (0); 535 } 536 #endif 537 538 int 539 sys_pipe2(struct thread *td, struct pipe2_args *uap) 540 { 541 int error, fildes[2]; 542 543 if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK)) 544 return (EINVAL); 545 error = kern_pipe(td, fildes, uap->flags, NULL, NULL); 546 if (error) 547 return (error); 548 error = copyout(fildes, uap->fildes, 2 * sizeof(int)); 549 if (error) { 550 (void)kern_close(td, fildes[0]); 551 (void)kern_close(td, fildes[1]); 552 } 553 return (error); 554 } 555 556 /* 557 * Allocate kva for pipe circular buffer, the space is pageable 558 * This routine will 'realloc' the size of a pipe safely, if it fails 559 * it will retain the old buffer. 560 * If it fails it will return ENOMEM. 561 */ 562 static int 563 pipespace_new(struct pipe *cpipe, int size) 564 { 565 caddr_t buffer; 566 int error, cnt, firstseg; 567 static int curfail = 0; 568 static struct timeval lastfail; 569 570 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked")); 571 KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW), 572 ("pipespace: resize of direct writes not allowed")); 573 retry: 574 cnt = cpipe->pipe_buffer.cnt; 575 if (cnt > size) 576 size = cnt; 577 578 size = round_page(size); 579 buffer = (caddr_t) vm_map_min(pipe_map); 580 581 error = vm_map_find(pipe_map, NULL, 0, (vm_offset_t *)&buffer, size, 0, 582 VMFS_ANY_SPACE, VM_PROT_RW, VM_PROT_RW, 0); 583 if (error != KERN_SUCCESS) { 584 if (cpipe->pipe_buffer.buffer == NULL && 585 size > SMALL_PIPE_SIZE) { 586 size = SMALL_PIPE_SIZE; 587 pipefragretry++; 588 goto retry; 589 } 590 if (cpipe->pipe_buffer.buffer == NULL) { 591 pipeallocfail++; 592 if (ppsratecheck(&lastfail, &curfail, 1)) 593 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n"); 594 } else { 595 piperesizefail++; 596 } 597 return (ENOMEM); 598 } 599 600 /* copy data, then free old resources if we're resizing */ 601 if (cnt > 0) { 602 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) { 603 firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out; 604 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 605 buffer, firstseg); 606 if ((cnt - firstseg) > 0) 607 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg], 608 cpipe->pipe_buffer.in); 609 } else { 610 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 611 buffer, cnt); 612 } 613 } 614 pipe_free_kmem(cpipe); 615 cpipe->pipe_buffer.buffer = buffer; 616 cpipe->pipe_buffer.size = size; 617 cpipe->pipe_buffer.in = cnt; 618 cpipe->pipe_buffer.out = 0; 619 cpipe->pipe_buffer.cnt = cnt; 620 atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size); 621 return (0); 622 } 623 624 /* 625 * Wrapper for pipespace_new() that performs locking assertions. 626 */ 627 static int 628 pipespace(struct pipe *cpipe, int size) 629 { 630 631 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 632 ("Unlocked pipe passed to pipespace")); 633 return (pipespace_new(cpipe, size)); 634 } 635 636 /* 637 * lock a pipe for I/O, blocking other access 638 */ 639 static __inline int 640 pipelock(struct pipe *cpipe, int catch) 641 { 642 int error, prio; 643 644 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 645 646 prio = PRIBIO; 647 if (catch) 648 prio |= PCATCH; 649 while (cpipe->pipe_state & PIPE_LOCKFL) { 650 KASSERT(cpipe->pipe_waiters >= 0, 651 ("%s: bad waiter count %d", __func__, 652 cpipe->pipe_waiters)); 653 cpipe->pipe_waiters++; 654 error = msleep(&cpipe->pipe_waiters, PIPE_MTX(cpipe), prio, 655 "pipelk", 0); 656 cpipe->pipe_waiters--; 657 if (error != 0) 658 return (error); 659 } 660 cpipe->pipe_state |= PIPE_LOCKFL; 661 return (0); 662 } 663 664 /* 665 * unlock a pipe I/O lock 666 */ 667 static __inline void 668 pipeunlock(struct pipe *cpipe) 669 { 670 671 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 672 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 673 ("Unlocked pipe passed to pipeunlock")); 674 KASSERT(cpipe->pipe_waiters >= 0, 675 ("%s: bad waiter count %d", __func__, 676 cpipe->pipe_waiters)); 677 cpipe->pipe_state &= ~PIPE_LOCKFL; 678 if (cpipe->pipe_waiters > 0) 679 wakeup_one(&cpipe->pipe_waiters); 680 } 681 682 void 683 pipeselwakeup(struct pipe *cpipe) 684 { 685 686 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 687 if (cpipe->pipe_state & PIPE_SEL) { 688 selwakeuppri(&cpipe->pipe_sel, PSOCK); 689 if (!SEL_WAITING(&cpipe->pipe_sel)) 690 cpipe->pipe_state &= ~PIPE_SEL; 691 } 692 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) 693 pgsigio(&cpipe->pipe_sigio, SIGIO, 0); 694 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0); 695 } 696 697 /* 698 * Initialize and allocate VM and memory for pipe. The structure 699 * will start out zero'd from the ctor, so we just manage the kmem. 700 */ 701 static int 702 pipe_create(struct pipe *pipe, bool large_backing) 703 { 704 int error; 705 706 error = pipespace_new(pipe, !large_backing || amountpipekva > 707 maxpipekva / 2 ? SMALL_PIPE_SIZE : PIPE_SIZE); 708 if (error == 0) 709 pipe->pipe_ino = alloc_unr64(&pipeino_unr); 710 return (error); 711 } 712 713 /* ARGSUSED */ 714 static int 715 pipe_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 716 int flags, struct thread *td) 717 { 718 struct pipe *rpipe; 719 int error; 720 int nread = 0; 721 int size; 722 723 rpipe = fp->f_data; 724 PIPE_LOCK(rpipe); 725 ++rpipe->pipe_busy; 726 error = pipelock(rpipe, 1); 727 if (error) 728 goto unlocked_error; 729 730 #ifdef MAC 731 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair); 732 if (error) 733 goto locked_error; 734 #endif 735 if (amountpipekva > (3 * maxpipekva) / 4) { 736 if ((rpipe->pipe_state & PIPE_DIRECTW) == 0 && 737 rpipe->pipe_buffer.size > SMALL_PIPE_SIZE && 738 rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE && 739 piperesizeallowed == 1) { 740 PIPE_UNLOCK(rpipe); 741 pipespace(rpipe, SMALL_PIPE_SIZE); 742 PIPE_LOCK(rpipe); 743 } 744 } 745 746 while (uio->uio_resid) { 747 /* 748 * normal pipe buffer receive 749 */ 750 if (rpipe->pipe_buffer.cnt > 0) { 751 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 752 if (size > rpipe->pipe_buffer.cnt) 753 size = rpipe->pipe_buffer.cnt; 754 if (size > uio->uio_resid) 755 size = uio->uio_resid; 756 757 PIPE_UNLOCK(rpipe); 758 error = uiomove( 759 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 760 size, uio); 761 PIPE_LOCK(rpipe); 762 if (error) 763 break; 764 765 rpipe->pipe_buffer.out += size; 766 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 767 rpipe->pipe_buffer.out = 0; 768 769 rpipe->pipe_buffer.cnt -= size; 770 771 /* 772 * If there is no more to read in the pipe, reset 773 * its pointers to the beginning. This improves 774 * cache hit stats. 775 */ 776 if (rpipe->pipe_buffer.cnt == 0) { 777 rpipe->pipe_buffer.in = 0; 778 rpipe->pipe_buffer.out = 0; 779 } 780 nread += size; 781 #ifndef PIPE_NODIRECT 782 /* 783 * Direct copy, bypassing a kernel buffer. 784 */ 785 } else if ((size = rpipe->pipe_pages.cnt) != 0) { 786 if (size > uio->uio_resid) 787 size = (u_int) uio->uio_resid; 788 PIPE_UNLOCK(rpipe); 789 error = uiomove_fromphys(rpipe->pipe_pages.ms, 790 rpipe->pipe_pages.pos, size, uio); 791 PIPE_LOCK(rpipe); 792 if (error) 793 break; 794 nread += size; 795 rpipe->pipe_pages.pos += size; 796 rpipe->pipe_pages.cnt -= size; 797 if (rpipe->pipe_pages.cnt == 0) { 798 rpipe->pipe_state &= ~PIPE_WANTW; 799 wakeup(rpipe); 800 } 801 #endif 802 } else { 803 /* 804 * detect EOF condition 805 * read returns 0 on EOF, no need to set error 806 */ 807 if (rpipe->pipe_state & PIPE_EOF) 808 break; 809 810 /* 811 * If the "write-side" has been blocked, wake it up now. 812 */ 813 if (rpipe->pipe_state & PIPE_WANTW) { 814 rpipe->pipe_state &= ~PIPE_WANTW; 815 wakeup(rpipe); 816 } 817 818 /* 819 * Break if some data was read. 820 */ 821 if (nread > 0) 822 break; 823 824 /* 825 * Unlock the pipe buffer for our remaining processing. 826 * We will either break out with an error or we will 827 * sleep and relock to loop. 828 */ 829 pipeunlock(rpipe); 830 831 /* 832 * Handle non-blocking mode operation or 833 * wait for more data. 834 */ 835 if (fp->f_flag & FNONBLOCK) { 836 error = EAGAIN; 837 } else { 838 rpipe->pipe_state |= PIPE_WANTR; 839 if ((error = msleep(rpipe, PIPE_MTX(rpipe), 840 PRIBIO | PCATCH, 841 "piperd", 0)) == 0) 842 error = pipelock(rpipe, 1); 843 } 844 if (error) 845 goto unlocked_error; 846 } 847 } 848 #ifdef MAC 849 locked_error: 850 #endif 851 pipeunlock(rpipe); 852 853 /* XXX: should probably do this before getting any locks. */ 854 if (error == 0) 855 pipe_timestamp(&rpipe->pipe_atime); 856 unlocked_error: 857 --rpipe->pipe_busy; 858 859 /* 860 * PIPE_WANT processing only makes sense if pipe_busy is 0. 861 */ 862 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 863 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 864 wakeup(rpipe); 865 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 866 /* 867 * Handle write blocking hysteresis. 868 */ 869 if (rpipe->pipe_state & PIPE_WANTW) { 870 rpipe->pipe_state &= ~PIPE_WANTW; 871 wakeup(rpipe); 872 } 873 } 874 875 /* 876 * Only wake up writers if there was actually something read. 877 * Otherwise, when calling read(2) at EOF, a spurious wakeup occurs. 878 */ 879 if (nread > 0 && 880 rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt >= PIPE_BUF) 881 pipeselwakeup(rpipe); 882 883 PIPE_UNLOCK(rpipe); 884 if (nread > 0) 885 td->td_ru.ru_msgrcv++; 886 return (error); 887 } 888 889 #ifndef PIPE_NODIRECT 890 /* 891 * Map the sending processes' buffer into kernel space and wire it. 892 * This is similar to a physical write operation. 893 */ 894 static int 895 pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio) 896 { 897 u_int size; 898 int i; 899 900 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 901 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0, 902 ("%s: PIPE_DIRECTW set on %p", __func__, wpipe)); 903 KASSERT(wpipe->pipe_pages.cnt == 0, 904 ("%s: pipe map for %p contains residual data", __func__, wpipe)); 905 906 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size) 907 size = wpipe->pipe_buffer.size; 908 else 909 size = uio->uio_iov->iov_len; 910 911 wpipe->pipe_state |= PIPE_DIRECTW; 912 PIPE_UNLOCK(wpipe); 913 i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 914 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ, 915 wpipe->pipe_pages.ms, PIPENPAGES); 916 PIPE_LOCK(wpipe); 917 if (i < 0) { 918 wpipe->pipe_state &= ~PIPE_DIRECTW; 919 return (EFAULT); 920 } 921 922 wpipe->pipe_pages.npages = i; 923 wpipe->pipe_pages.pos = 924 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 925 wpipe->pipe_pages.cnt = size; 926 927 uio->uio_iov->iov_len -= size; 928 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size; 929 if (uio->uio_iov->iov_len == 0) 930 uio->uio_iov++; 931 uio->uio_resid -= size; 932 uio->uio_offset += size; 933 return (0); 934 } 935 936 /* 937 * Unwire the process buffer. 938 */ 939 static void 940 pipe_destroy_write_buffer(struct pipe *wpipe) 941 { 942 943 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 944 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0, 945 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe)); 946 KASSERT(wpipe->pipe_pages.cnt == 0, 947 ("%s: pipe map for %p contains residual data", __func__, wpipe)); 948 949 wpipe->pipe_state &= ~PIPE_DIRECTW; 950 vm_page_unhold_pages(wpipe->pipe_pages.ms, wpipe->pipe_pages.npages); 951 wpipe->pipe_pages.npages = 0; 952 } 953 954 /* 955 * In the case of a signal, the writing process might go away. This 956 * code copies the data into the circular buffer so that the source 957 * pages can be freed without loss of data. 958 */ 959 static void 960 pipe_clone_write_buffer(struct pipe *wpipe) 961 { 962 struct uio uio; 963 struct iovec iov; 964 int size; 965 int pos; 966 967 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 968 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0, 969 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe)); 970 971 size = wpipe->pipe_pages.cnt; 972 pos = wpipe->pipe_pages.pos; 973 wpipe->pipe_pages.cnt = 0; 974 975 wpipe->pipe_buffer.in = size; 976 wpipe->pipe_buffer.out = 0; 977 wpipe->pipe_buffer.cnt = size; 978 979 PIPE_UNLOCK(wpipe); 980 iov.iov_base = wpipe->pipe_buffer.buffer; 981 iov.iov_len = size; 982 uio.uio_iov = &iov; 983 uio.uio_iovcnt = 1; 984 uio.uio_offset = 0; 985 uio.uio_resid = size; 986 uio.uio_segflg = UIO_SYSSPACE; 987 uio.uio_rw = UIO_READ; 988 uio.uio_td = curthread; 989 uiomove_fromphys(wpipe->pipe_pages.ms, pos, size, &uio); 990 PIPE_LOCK(wpipe); 991 pipe_destroy_write_buffer(wpipe); 992 } 993 994 /* 995 * This implements the pipe buffer write mechanism. Note that only 996 * a direct write OR a normal pipe write can be pending at any given time. 997 * If there are any characters in the pipe buffer, the direct write will 998 * be deferred until the receiving process grabs all of the bytes from 999 * the pipe buffer. Then the direct mapping write is set-up. 1000 */ 1001 static int 1002 pipe_direct_write(struct pipe *wpipe, struct uio *uio) 1003 { 1004 int error; 1005 1006 retry: 1007 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 1008 if ((wpipe->pipe_state & PIPE_EOF) != 0) { 1009 error = EPIPE; 1010 goto error1; 1011 } 1012 if (wpipe->pipe_state & PIPE_DIRECTW) { 1013 if (wpipe->pipe_state & PIPE_WANTR) { 1014 wpipe->pipe_state &= ~PIPE_WANTR; 1015 wakeup(wpipe); 1016 } 1017 pipeselwakeup(wpipe); 1018 wpipe->pipe_state |= PIPE_WANTW; 1019 pipeunlock(wpipe); 1020 error = msleep(wpipe, PIPE_MTX(wpipe), 1021 PRIBIO | PCATCH, "pipdww", 0); 1022 pipelock(wpipe, 0); 1023 if (error != 0) 1024 goto error1; 1025 goto retry; 1026 } 1027 if (wpipe->pipe_buffer.cnt > 0) { 1028 if (wpipe->pipe_state & PIPE_WANTR) { 1029 wpipe->pipe_state &= ~PIPE_WANTR; 1030 wakeup(wpipe); 1031 } 1032 pipeselwakeup(wpipe); 1033 wpipe->pipe_state |= PIPE_WANTW; 1034 pipeunlock(wpipe); 1035 error = msleep(wpipe, PIPE_MTX(wpipe), 1036 PRIBIO | PCATCH, "pipdwc", 0); 1037 pipelock(wpipe, 0); 1038 if (error != 0) 1039 goto error1; 1040 goto retry; 1041 } 1042 1043 error = pipe_build_write_buffer(wpipe, uio); 1044 if (error) { 1045 goto error1; 1046 } 1047 1048 while (wpipe->pipe_pages.cnt != 0 && 1049 (wpipe->pipe_state & PIPE_EOF) == 0) { 1050 if (wpipe->pipe_state & PIPE_WANTR) { 1051 wpipe->pipe_state &= ~PIPE_WANTR; 1052 wakeup(wpipe); 1053 } 1054 pipeselwakeup(wpipe); 1055 wpipe->pipe_state |= PIPE_WANTW; 1056 pipeunlock(wpipe); 1057 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH, 1058 "pipdwt", 0); 1059 pipelock(wpipe, 0); 1060 if (error != 0) 1061 break; 1062 } 1063 1064 if ((wpipe->pipe_state & PIPE_EOF) != 0) { 1065 wpipe->pipe_pages.cnt = 0; 1066 pipe_destroy_write_buffer(wpipe); 1067 pipeselwakeup(wpipe); 1068 error = EPIPE; 1069 } else if (error == EINTR || error == ERESTART) { 1070 pipe_clone_write_buffer(wpipe); 1071 } else { 1072 pipe_destroy_write_buffer(wpipe); 1073 } 1074 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0, 1075 ("pipe %p leaked PIPE_DIRECTW", wpipe)); 1076 return (error); 1077 1078 error1: 1079 wakeup(wpipe); 1080 return (error); 1081 } 1082 #endif 1083 1084 static int 1085 pipe_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 1086 int flags, struct thread *td) 1087 { 1088 struct pipe *wpipe, *rpipe; 1089 ssize_t orig_resid; 1090 int desiredsize, error; 1091 1092 rpipe = fp->f_data; 1093 wpipe = PIPE_PEER(rpipe); 1094 PIPE_LOCK(rpipe); 1095 error = pipelock(wpipe, 1); 1096 if (error) { 1097 PIPE_UNLOCK(rpipe); 1098 return (error); 1099 } 1100 /* 1101 * detect loss of pipe read side, issue SIGPIPE if lost. 1102 */ 1103 if (wpipe->pipe_present != PIPE_ACTIVE || 1104 (wpipe->pipe_state & PIPE_EOF)) { 1105 pipeunlock(wpipe); 1106 PIPE_UNLOCK(rpipe); 1107 return (EPIPE); 1108 } 1109 #ifdef MAC 1110 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair); 1111 if (error) { 1112 pipeunlock(wpipe); 1113 PIPE_UNLOCK(rpipe); 1114 return (error); 1115 } 1116 #endif 1117 ++wpipe->pipe_busy; 1118 1119 /* Choose a larger size if it's advantageous */ 1120 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size); 1121 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) { 1122 if (piperesizeallowed != 1) 1123 break; 1124 if (amountpipekva > maxpipekva / 2) 1125 break; 1126 if (desiredsize == BIG_PIPE_SIZE) 1127 break; 1128 desiredsize = desiredsize * 2; 1129 } 1130 1131 /* Choose a smaller size if we're in a OOM situation */ 1132 if (amountpipekva > (3 * maxpipekva) / 4 && 1133 wpipe->pipe_buffer.size > SMALL_PIPE_SIZE && 1134 wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE && 1135 piperesizeallowed == 1) 1136 desiredsize = SMALL_PIPE_SIZE; 1137 1138 /* Resize if the above determined that a new size was necessary */ 1139 if (desiredsize != wpipe->pipe_buffer.size && 1140 (wpipe->pipe_state & PIPE_DIRECTW) == 0) { 1141 PIPE_UNLOCK(wpipe); 1142 pipespace(wpipe, desiredsize); 1143 PIPE_LOCK(wpipe); 1144 } 1145 MPASS(wpipe->pipe_buffer.size != 0); 1146 1147 orig_resid = uio->uio_resid; 1148 1149 while (uio->uio_resid) { 1150 int space; 1151 1152 if (wpipe->pipe_state & PIPE_EOF) { 1153 error = EPIPE; 1154 break; 1155 } 1156 #ifndef PIPE_NODIRECT 1157 /* 1158 * If the transfer is large, we can gain performance if 1159 * we do process-to-process copies directly. 1160 * If the write is non-blocking, we don't use the 1161 * direct write mechanism. 1162 * 1163 * The direct write mechanism will detect the reader going 1164 * away on us. 1165 */ 1166 if (uio->uio_segflg == UIO_USERSPACE && 1167 uio->uio_iov->iov_len >= pipe_mindirect && 1168 wpipe->pipe_buffer.size >= pipe_mindirect && 1169 (fp->f_flag & FNONBLOCK) == 0) { 1170 error = pipe_direct_write(wpipe, uio); 1171 if (error != 0) 1172 break; 1173 continue; 1174 } 1175 #endif 1176 1177 /* 1178 * Pipe buffered writes cannot be coincidental with 1179 * direct writes. We wait until the currently executing 1180 * direct write is completed before we start filling the 1181 * pipe buffer. We break out if a signal occurs or the 1182 * reader goes away. 1183 */ 1184 if (wpipe->pipe_pages.cnt != 0) { 1185 if (wpipe->pipe_state & PIPE_WANTR) { 1186 wpipe->pipe_state &= ~PIPE_WANTR; 1187 wakeup(wpipe); 1188 } 1189 pipeselwakeup(wpipe); 1190 wpipe->pipe_state |= PIPE_WANTW; 1191 pipeunlock(wpipe); 1192 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH, 1193 "pipbww", 0); 1194 pipelock(wpipe, 0); 1195 if (error != 0) 1196 break; 1197 continue; 1198 } 1199 1200 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1201 1202 /* Writes of size <= PIPE_BUF must be atomic. */ 1203 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 1204 space = 0; 1205 1206 if (space > 0) { 1207 int size; /* Transfer size */ 1208 int segsize; /* first segment to transfer */ 1209 1210 /* 1211 * Transfer size is minimum of uio transfer 1212 * and free space in pipe buffer. 1213 */ 1214 if (space > uio->uio_resid) 1215 size = uio->uio_resid; 1216 else 1217 size = space; 1218 /* 1219 * First segment to transfer is minimum of 1220 * transfer size and contiguous space in 1221 * pipe buffer. If first segment to transfer 1222 * is less than the transfer size, we've got 1223 * a wraparound in the buffer. 1224 */ 1225 segsize = wpipe->pipe_buffer.size - 1226 wpipe->pipe_buffer.in; 1227 if (segsize > size) 1228 segsize = size; 1229 1230 /* Transfer first segment */ 1231 1232 PIPE_UNLOCK(rpipe); 1233 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 1234 segsize, uio); 1235 PIPE_LOCK(rpipe); 1236 1237 if (error == 0 && segsize < size) { 1238 KASSERT(wpipe->pipe_buffer.in + segsize == 1239 wpipe->pipe_buffer.size, 1240 ("Pipe buffer wraparound disappeared")); 1241 /* 1242 * Transfer remaining part now, to 1243 * support atomic writes. Wraparound 1244 * happened. 1245 */ 1246 1247 PIPE_UNLOCK(rpipe); 1248 error = uiomove( 1249 &wpipe->pipe_buffer.buffer[0], 1250 size - segsize, uio); 1251 PIPE_LOCK(rpipe); 1252 } 1253 if (error == 0) { 1254 wpipe->pipe_buffer.in += size; 1255 if (wpipe->pipe_buffer.in >= 1256 wpipe->pipe_buffer.size) { 1257 KASSERT(wpipe->pipe_buffer.in == 1258 size - segsize + 1259 wpipe->pipe_buffer.size, 1260 ("Expected wraparound bad")); 1261 wpipe->pipe_buffer.in = size - segsize; 1262 } 1263 1264 wpipe->pipe_buffer.cnt += size; 1265 KASSERT(wpipe->pipe_buffer.cnt <= 1266 wpipe->pipe_buffer.size, 1267 ("Pipe buffer overflow")); 1268 } 1269 if (error != 0) 1270 break; 1271 continue; 1272 } else { 1273 /* 1274 * If the "read-side" has been blocked, wake it up now. 1275 */ 1276 if (wpipe->pipe_state & PIPE_WANTR) { 1277 wpipe->pipe_state &= ~PIPE_WANTR; 1278 wakeup(wpipe); 1279 } 1280 1281 /* 1282 * don't block on non-blocking I/O 1283 */ 1284 if (fp->f_flag & FNONBLOCK) { 1285 error = EAGAIN; 1286 break; 1287 } 1288 1289 /* 1290 * We have no more space and have something to offer, 1291 * wake up select/poll. 1292 */ 1293 pipeselwakeup(wpipe); 1294 1295 wpipe->pipe_state |= PIPE_WANTW; 1296 pipeunlock(wpipe); 1297 error = msleep(wpipe, PIPE_MTX(rpipe), 1298 PRIBIO | PCATCH, "pipewr", 0); 1299 pipelock(wpipe, 0); 1300 if (error != 0) 1301 break; 1302 continue; 1303 } 1304 } 1305 1306 --wpipe->pipe_busy; 1307 1308 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 1309 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 1310 wakeup(wpipe); 1311 } else if (wpipe->pipe_buffer.cnt > 0) { 1312 /* 1313 * If we have put any characters in the buffer, we wake up 1314 * the reader. 1315 */ 1316 if (wpipe->pipe_state & PIPE_WANTR) { 1317 wpipe->pipe_state &= ~PIPE_WANTR; 1318 wakeup(wpipe); 1319 } 1320 } 1321 1322 /* 1323 * Don't return EPIPE if any byte was written. 1324 * EINTR and other interrupts are handled by generic I/O layer. 1325 * Do not pretend that I/O succeeded for obvious user error 1326 * like EFAULT. 1327 */ 1328 if (uio->uio_resid != orig_resid && error == EPIPE) 1329 error = 0; 1330 1331 if (error == 0) 1332 pipe_timestamp(&wpipe->pipe_mtime); 1333 1334 /* 1335 * We have something to offer, 1336 * wake up select/poll. 1337 */ 1338 if (wpipe->pipe_buffer.cnt) 1339 pipeselwakeup(wpipe); 1340 1341 pipeunlock(wpipe); 1342 PIPE_UNLOCK(rpipe); 1343 if (uio->uio_resid != orig_resid) 1344 td->td_ru.ru_msgsnd++; 1345 return (error); 1346 } 1347 1348 /* ARGSUSED */ 1349 static int 1350 pipe_truncate(struct file *fp, off_t length, struct ucred *active_cred, 1351 struct thread *td) 1352 { 1353 struct pipe *cpipe; 1354 int error; 1355 1356 cpipe = fp->f_data; 1357 if (cpipe->pipe_type & PIPE_TYPE_NAMED) 1358 error = vnops.fo_truncate(fp, length, active_cred, td); 1359 else 1360 error = invfo_truncate(fp, length, active_cred, td); 1361 return (error); 1362 } 1363 1364 /* 1365 * we implement a very minimal set of ioctls for compatibility with sockets. 1366 */ 1367 static int 1368 pipe_ioctl(struct file *fp, u_long cmd, void *data, struct ucred *active_cred, 1369 struct thread *td) 1370 { 1371 struct pipe *mpipe = fp->f_data; 1372 int error; 1373 1374 PIPE_LOCK(mpipe); 1375 1376 #ifdef MAC 1377 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data); 1378 if (error) { 1379 PIPE_UNLOCK(mpipe); 1380 return (error); 1381 } 1382 #endif 1383 1384 error = 0; 1385 switch (cmd) { 1386 case FIONBIO: 1387 break; 1388 1389 case FIOASYNC: 1390 if (*(int *)data) { 1391 mpipe->pipe_state |= PIPE_ASYNC; 1392 } else { 1393 mpipe->pipe_state &= ~PIPE_ASYNC; 1394 } 1395 break; 1396 1397 case FIONREAD: 1398 if (!(fp->f_flag & FREAD)) { 1399 *(int *)data = 0; 1400 PIPE_UNLOCK(mpipe); 1401 return (0); 1402 } 1403 if (mpipe->pipe_pages.cnt != 0) 1404 *(int *)data = mpipe->pipe_pages.cnt; 1405 else 1406 *(int *)data = mpipe->pipe_buffer.cnt; 1407 break; 1408 1409 case FIOSETOWN: 1410 PIPE_UNLOCK(mpipe); 1411 error = fsetown(*(int *)data, &mpipe->pipe_sigio); 1412 goto out_unlocked; 1413 1414 case FIOGETOWN: 1415 *(int *)data = fgetown(&mpipe->pipe_sigio); 1416 break; 1417 1418 /* This is deprecated, FIOSETOWN should be used instead. */ 1419 case TIOCSPGRP: 1420 PIPE_UNLOCK(mpipe); 1421 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio); 1422 goto out_unlocked; 1423 1424 /* This is deprecated, FIOGETOWN should be used instead. */ 1425 case TIOCGPGRP: 1426 *(int *)data = -fgetown(&mpipe->pipe_sigio); 1427 break; 1428 1429 default: 1430 error = ENOTTY; 1431 break; 1432 } 1433 PIPE_UNLOCK(mpipe); 1434 out_unlocked: 1435 return (error); 1436 } 1437 1438 static int 1439 pipe_poll(struct file *fp, int events, struct ucred *active_cred, 1440 struct thread *td) 1441 { 1442 struct pipe *rpipe; 1443 struct pipe *wpipe; 1444 int levents, revents; 1445 #ifdef MAC 1446 int error; 1447 #endif 1448 1449 revents = 0; 1450 rpipe = fp->f_data; 1451 wpipe = PIPE_PEER(rpipe); 1452 PIPE_LOCK(rpipe); 1453 #ifdef MAC 1454 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair); 1455 if (error) 1456 goto locked_error; 1457 #endif 1458 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) 1459 if (rpipe->pipe_pages.cnt > 0 || rpipe->pipe_buffer.cnt > 0) 1460 revents |= events & (POLLIN | POLLRDNORM); 1461 1462 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) 1463 if (wpipe->pipe_present != PIPE_ACTIVE || 1464 (wpipe->pipe_state & PIPE_EOF) || 1465 ((wpipe->pipe_state & PIPE_DIRECTW) == 0 && 1466 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF || 1467 wpipe->pipe_buffer.size == 0))) 1468 revents |= events & (POLLOUT | POLLWRNORM); 1469 1470 levents = events & 1471 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND); 1472 if (rpipe->pipe_type & PIPE_TYPE_NAMED && fp->f_flag & FREAD && levents && 1473 fp->f_pipegen == rpipe->pipe_wgen) 1474 events |= POLLINIGNEOF; 1475 1476 if ((events & POLLINIGNEOF) == 0) { 1477 if (rpipe->pipe_state & PIPE_EOF) { 1478 if (fp->f_flag & FREAD) 1479 revents |= (events & (POLLIN | POLLRDNORM)); 1480 if (wpipe->pipe_present != PIPE_ACTIVE || 1481 (wpipe->pipe_state & PIPE_EOF)) 1482 revents |= POLLHUP; 1483 } 1484 } 1485 1486 if (revents == 0) { 1487 /* 1488 * Add ourselves regardless of eventmask as we have to return 1489 * POLLHUP even if it was not asked for. 1490 */ 1491 if ((fp->f_flag & FREAD) != 0) { 1492 selrecord(td, &rpipe->pipe_sel); 1493 if (SEL_WAITING(&rpipe->pipe_sel)) 1494 rpipe->pipe_state |= PIPE_SEL; 1495 } 1496 1497 if ((fp->f_flag & FWRITE) != 0 && 1498 wpipe->pipe_present == PIPE_ACTIVE) { 1499 selrecord(td, &wpipe->pipe_sel); 1500 if (SEL_WAITING(&wpipe->pipe_sel)) 1501 wpipe->pipe_state |= PIPE_SEL; 1502 } 1503 } 1504 #ifdef MAC 1505 locked_error: 1506 #endif 1507 PIPE_UNLOCK(rpipe); 1508 1509 return (revents); 1510 } 1511 1512 /* 1513 * We shouldn't need locks here as we're doing a read and this should 1514 * be a natural race. 1515 */ 1516 static int 1517 pipe_stat(struct file *fp, struct stat *ub, struct ucred *active_cred) 1518 { 1519 struct pipe *pipe; 1520 #ifdef MAC 1521 int error; 1522 #endif 1523 1524 pipe = fp->f_data; 1525 #ifdef MAC 1526 if (mac_pipe_check_stat_enabled()) { 1527 PIPE_LOCK(pipe); 1528 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair); 1529 PIPE_UNLOCK(pipe); 1530 if (error) { 1531 return (error); 1532 } 1533 } 1534 #endif 1535 1536 /* For named pipes ask the underlying filesystem. */ 1537 if (pipe->pipe_type & PIPE_TYPE_NAMED) { 1538 return (vnops.fo_stat(fp, ub, active_cred)); 1539 } 1540 1541 bzero(ub, sizeof(*ub)); 1542 ub->st_mode = S_IFIFO; 1543 ub->st_blksize = PAGE_SIZE; 1544 if (pipe->pipe_pages.cnt != 0) 1545 ub->st_size = pipe->pipe_pages.cnt; 1546 else 1547 ub->st_size = pipe->pipe_buffer.cnt; 1548 ub->st_blocks = howmany(ub->st_size, ub->st_blksize); 1549 ub->st_atim = pipe->pipe_atime; 1550 ub->st_mtim = pipe->pipe_mtime; 1551 ub->st_ctim = pipe->pipe_ctime; 1552 ub->st_uid = fp->f_cred->cr_uid; 1553 ub->st_gid = fp->f_cred->cr_gid; 1554 ub->st_dev = pipedev_ino; 1555 ub->st_ino = pipe->pipe_ino; 1556 /* 1557 * Left as 0: st_nlink, st_rdev, st_flags, st_gen. 1558 */ 1559 return (0); 1560 } 1561 1562 /* ARGSUSED */ 1563 static int 1564 pipe_close(struct file *fp, struct thread *td) 1565 { 1566 1567 if (fp->f_vnode != NULL) 1568 return vnops.fo_close(fp, td); 1569 fp->f_ops = &badfileops; 1570 pipe_dtor(fp->f_data); 1571 fp->f_data = NULL; 1572 return (0); 1573 } 1574 1575 static int 1576 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td) 1577 { 1578 struct pipe *cpipe; 1579 int error; 1580 1581 cpipe = fp->f_data; 1582 if (cpipe->pipe_type & PIPE_TYPE_NAMED) 1583 error = vn_chmod(fp, mode, active_cred, td); 1584 else 1585 error = invfo_chmod(fp, mode, active_cred, td); 1586 return (error); 1587 } 1588 1589 static int 1590 pipe_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1591 struct thread *td) 1592 { 1593 struct pipe *cpipe; 1594 int error; 1595 1596 cpipe = fp->f_data; 1597 if (cpipe->pipe_type & PIPE_TYPE_NAMED) 1598 error = vn_chown(fp, uid, gid, active_cred, td); 1599 else 1600 error = invfo_chown(fp, uid, gid, active_cred, td); 1601 return (error); 1602 } 1603 1604 static int 1605 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp) 1606 { 1607 struct pipe *pi; 1608 1609 if (fp->f_type == DTYPE_FIFO) 1610 return (vn_fill_kinfo(fp, kif, fdp)); 1611 kif->kf_type = KF_TYPE_PIPE; 1612 pi = fp->f_data; 1613 kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi; 1614 kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer; 1615 kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt; 1616 kif->kf_un.kf_pipe.kf_pipe_buffer_in = pi->pipe_buffer.in; 1617 kif->kf_un.kf_pipe.kf_pipe_buffer_out = pi->pipe_buffer.out; 1618 kif->kf_un.kf_pipe.kf_pipe_buffer_size = pi->pipe_buffer.size; 1619 return (0); 1620 } 1621 1622 static void 1623 pipe_free_kmem(struct pipe *cpipe) 1624 { 1625 1626 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), 1627 ("pipe_free_kmem: pipe mutex locked")); 1628 1629 if (cpipe->pipe_buffer.buffer != NULL) { 1630 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size); 1631 vm_map_remove(pipe_map, 1632 (vm_offset_t)cpipe->pipe_buffer.buffer, 1633 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size); 1634 cpipe->pipe_buffer.buffer = NULL; 1635 } 1636 #ifndef PIPE_NODIRECT 1637 { 1638 cpipe->pipe_pages.cnt = 0; 1639 cpipe->pipe_pages.pos = 0; 1640 cpipe->pipe_pages.npages = 0; 1641 } 1642 #endif 1643 } 1644 1645 /* 1646 * shutdown the pipe 1647 */ 1648 static void 1649 pipeclose(struct pipe *cpipe) 1650 { 1651 #ifdef MAC 1652 struct pipepair *pp; 1653 #endif 1654 struct pipe *ppipe; 1655 1656 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL")); 1657 1658 PIPE_LOCK(cpipe); 1659 pipelock(cpipe, 0); 1660 #ifdef MAC 1661 pp = cpipe->pipe_pair; 1662 #endif 1663 1664 /* 1665 * If the other side is blocked, wake it up saying that 1666 * we want to close it down. 1667 */ 1668 cpipe->pipe_state |= PIPE_EOF; 1669 while (cpipe->pipe_busy) { 1670 wakeup(cpipe); 1671 cpipe->pipe_state |= PIPE_WANT; 1672 pipeunlock(cpipe); 1673 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0); 1674 pipelock(cpipe, 0); 1675 } 1676 1677 pipeselwakeup(cpipe); 1678 1679 /* 1680 * Disconnect from peer, if any. 1681 */ 1682 ppipe = cpipe->pipe_peer; 1683 if (ppipe->pipe_present == PIPE_ACTIVE) { 1684 ppipe->pipe_state |= PIPE_EOF; 1685 wakeup(ppipe); 1686 pipeselwakeup(ppipe); 1687 } 1688 1689 /* 1690 * Mark this endpoint as free. Release kmem resources. We 1691 * don't mark this endpoint as unused until we've finished 1692 * doing that, or the pipe might disappear out from under 1693 * us. 1694 */ 1695 PIPE_UNLOCK(cpipe); 1696 pipe_free_kmem(cpipe); 1697 PIPE_LOCK(cpipe); 1698 cpipe->pipe_present = PIPE_CLOSING; 1699 pipeunlock(cpipe); 1700 1701 /* 1702 * knlist_clear() may sleep dropping the PIPE_MTX. Set the 1703 * PIPE_FINALIZED, that allows other end to free the 1704 * pipe_pair, only after the knotes are completely dismantled. 1705 */ 1706 knlist_clear(&cpipe->pipe_sel.si_note, 1); 1707 cpipe->pipe_present = PIPE_FINALIZED; 1708 seldrain(&cpipe->pipe_sel); 1709 knlist_destroy(&cpipe->pipe_sel.si_note); 1710 1711 /* 1712 * If both endpoints are now closed, release the memory for the 1713 * pipe pair. If not, unlock. 1714 */ 1715 if (ppipe->pipe_present == PIPE_FINALIZED) { 1716 PIPE_UNLOCK(cpipe); 1717 #ifdef MAC 1718 mac_pipe_destroy(pp); 1719 #endif 1720 uma_zfree(pipe_zone, cpipe->pipe_pair); 1721 } else 1722 PIPE_UNLOCK(cpipe); 1723 } 1724 1725 /*ARGSUSED*/ 1726 static int 1727 pipe_kqfilter(struct file *fp, struct knote *kn) 1728 { 1729 struct pipe *cpipe; 1730 1731 /* 1732 * If a filter is requested that is not supported by this file 1733 * descriptor, don't return an error, but also don't ever generate an 1734 * event. 1735 */ 1736 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) { 1737 kn->kn_fop = &pipe_nfiltops; 1738 return (0); 1739 } 1740 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) { 1741 kn->kn_fop = &pipe_nfiltops; 1742 return (0); 1743 } 1744 cpipe = fp->f_data; 1745 PIPE_LOCK(cpipe); 1746 switch (kn->kn_filter) { 1747 case EVFILT_READ: 1748 kn->kn_fop = &pipe_rfiltops; 1749 break; 1750 case EVFILT_WRITE: 1751 kn->kn_fop = &pipe_wfiltops; 1752 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) { 1753 /* other end of pipe has been closed */ 1754 PIPE_UNLOCK(cpipe); 1755 return (EPIPE); 1756 } 1757 cpipe = PIPE_PEER(cpipe); 1758 break; 1759 default: 1760 if ((cpipe->pipe_type & PIPE_TYPE_NAMED) != 0) { 1761 PIPE_UNLOCK(cpipe); 1762 return (vnops.fo_kqfilter(fp, kn)); 1763 } 1764 PIPE_UNLOCK(cpipe); 1765 return (EINVAL); 1766 } 1767 1768 kn->kn_hook = cpipe; 1769 knlist_add(&cpipe->pipe_sel.si_note, kn, 1); 1770 PIPE_UNLOCK(cpipe); 1771 return (0); 1772 } 1773 1774 static void 1775 filt_pipedetach(struct knote *kn) 1776 { 1777 struct pipe *cpipe = kn->kn_hook; 1778 1779 PIPE_LOCK(cpipe); 1780 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1); 1781 PIPE_UNLOCK(cpipe); 1782 } 1783 1784 /*ARGSUSED*/ 1785 static int 1786 filt_piperead(struct knote *kn, long hint) 1787 { 1788 struct file *fp = kn->kn_fp; 1789 struct pipe *rpipe = kn->kn_hook; 1790 1791 PIPE_LOCK_ASSERT(rpipe, MA_OWNED); 1792 kn->kn_data = rpipe->pipe_buffer.cnt; 1793 if (kn->kn_data == 0) 1794 kn->kn_data = rpipe->pipe_pages.cnt; 1795 1796 if ((rpipe->pipe_state & PIPE_EOF) != 0 && 1797 ((rpipe->pipe_type & PIPE_TYPE_NAMED) == 0 || 1798 fp->f_pipegen != rpipe->pipe_wgen)) { 1799 kn->kn_flags |= EV_EOF; 1800 return (1); 1801 } 1802 kn->kn_flags &= ~EV_EOF; 1803 return (kn->kn_data > 0); 1804 } 1805 1806 /*ARGSUSED*/ 1807 static int 1808 filt_pipewrite(struct knote *kn, long hint) 1809 { 1810 struct pipe *wpipe = kn->kn_hook; 1811 1812 /* 1813 * If this end of the pipe is closed, the knote was removed from the 1814 * knlist and the list lock (i.e., the pipe lock) is therefore not held. 1815 */ 1816 if (wpipe->pipe_present == PIPE_ACTIVE || 1817 (wpipe->pipe_type & PIPE_TYPE_NAMED) != 0) { 1818 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 1819 1820 if (wpipe->pipe_state & PIPE_DIRECTW) { 1821 kn->kn_data = 0; 1822 } else if (wpipe->pipe_buffer.size > 0) { 1823 kn->kn_data = wpipe->pipe_buffer.size - 1824 wpipe->pipe_buffer.cnt; 1825 } else { 1826 kn->kn_data = PIPE_BUF; 1827 } 1828 } 1829 1830 if (wpipe->pipe_present != PIPE_ACTIVE || 1831 (wpipe->pipe_state & PIPE_EOF)) { 1832 kn->kn_flags |= EV_EOF; 1833 return (1); 1834 } 1835 kn->kn_flags &= ~EV_EOF; 1836 return (kn->kn_data >= PIPE_BUF); 1837 } 1838 1839 static void 1840 filt_pipedetach_notsup(struct knote *kn) 1841 { 1842 1843 } 1844 1845 static int 1846 filt_pipenotsup(struct knote *kn, long hint) 1847 { 1848 1849 return (0); 1850 } 1851