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_MTX(cpipe), 655 prio, "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); 680 } 681 } 682 683 void 684 pipeselwakeup(struct pipe *cpipe) 685 { 686 687 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 688 if (cpipe->pipe_state & PIPE_SEL) { 689 selwakeuppri(&cpipe->pipe_sel, PSOCK); 690 if (!SEL_WAITING(&cpipe->pipe_sel)) 691 cpipe->pipe_state &= ~PIPE_SEL; 692 } 693 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) 694 pgsigio(&cpipe->pipe_sigio, SIGIO, 0); 695 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0); 696 } 697 698 /* 699 * Initialize and allocate VM and memory for pipe. The structure 700 * will start out zero'd from the ctor, so we just manage the kmem. 701 */ 702 static int 703 pipe_create(struct pipe *pipe, bool large_backing) 704 { 705 int error; 706 707 error = pipespace_new(pipe, !large_backing || amountpipekva > 708 maxpipekva / 2 ? SMALL_PIPE_SIZE : PIPE_SIZE); 709 if (error == 0) 710 pipe->pipe_ino = alloc_unr64(&pipeino_unr); 711 return (error); 712 } 713 714 /* ARGSUSED */ 715 static int 716 pipe_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 717 int flags, struct thread *td) 718 { 719 struct pipe *rpipe; 720 int error; 721 int nread = 0; 722 int size; 723 724 rpipe = fp->f_data; 725 PIPE_LOCK(rpipe); 726 ++rpipe->pipe_busy; 727 error = pipelock(rpipe, 1); 728 if (error) 729 goto unlocked_error; 730 731 #ifdef MAC 732 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair); 733 if (error) 734 goto locked_error; 735 #endif 736 if (amountpipekva > (3 * maxpipekva) / 4) { 737 if ((rpipe->pipe_state & PIPE_DIRECTW) == 0 && 738 rpipe->pipe_buffer.size > SMALL_PIPE_SIZE && 739 rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE && 740 piperesizeallowed == 1) { 741 PIPE_UNLOCK(rpipe); 742 pipespace(rpipe, SMALL_PIPE_SIZE); 743 PIPE_LOCK(rpipe); 744 } 745 } 746 747 while (uio->uio_resid) { 748 /* 749 * normal pipe buffer receive 750 */ 751 if (rpipe->pipe_buffer.cnt > 0) { 752 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 753 if (size > rpipe->pipe_buffer.cnt) 754 size = rpipe->pipe_buffer.cnt; 755 if (size > uio->uio_resid) 756 size = uio->uio_resid; 757 758 PIPE_UNLOCK(rpipe); 759 error = uiomove( 760 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 761 size, uio); 762 PIPE_LOCK(rpipe); 763 if (error) 764 break; 765 766 rpipe->pipe_buffer.out += size; 767 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 768 rpipe->pipe_buffer.out = 0; 769 770 rpipe->pipe_buffer.cnt -= size; 771 772 /* 773 * If there is no more to read in the pipe, reset 774 * its pointers to the beginning. This improves 775 * cache hit stats. 776 */ 777 if (rpipe->pipe_buffer.cnt == 0) { 778 rpipe->pipe_buffer.in = 0; 779 rpipe->pipe_buffer.out = 0; 780 } 781 nread += size; 782 #ifndef PIPE_NODIRECT 783 /* 784 * Direct copy, bypassing a kernel buffer. 785 */ 786 } else if ((size = rpipe->pipe_pages.cnt) != 0) { 787 if (size > uio->uio_resid) 788 size = (u_int) uio->uio_resid; 789 PIPE_UNLOCK(rpipe); 790 error = uiomove_fromphys(rpipe->pipe_pages.ms, 791 rpipe->pipe_pages.pos, size, uio); 792 PIPE_LOCK(rpipe); 793 if (error) 794 break; 795 nread += size; 796 rpipe->pipe_pages.pos += size; 797 rpipe->pipe_pages.cnt -= size; 798 if (rpipe->pipe_pages.cnt == 0) { 799 rpipe->pipe_state &= ~PIPE_WANTW; 800 wakeup(rpipe); 801 } 802 #endif 803 } else { 804 /* 805 * detect EOF condition 806 * read returns 0 on EOF, no need to set error 807 */ 808 if (rpipe->pipe_state & PIPE_EOF) 809 break; 810 811 /* 812 * If the "write-side" has been blocked, wake it up now. 813 */ 814 if (rpipe->pipe_state & PIPE_WANTW) { 815 rpipe->pipe_state &= ~PIPE_WANTW; 816 wakeup(rpipe); 817 } 818 819 /* 820 * Break if some data was read. 821 */ 822 if (nread > 0) 823 break; 824 825 /* 826 * Unlock the pipe buffer for our remaining processing. 827 * We will either break out with an error or we will 828 * sleep and relock to loop. 829 */ 830 pipeunlock(rpipe); 831 832 /* 833 * Handle non-blocking mode operation or 834 * wait for more data. 835 */ 836 if (fp->f_flag & FNONBLOCK) { 837 error = EAGAIN; 838 } else { 839 rpipe->pipe_state |= PIPE_WANTR; 840 if ((error = msleep(rpipe, PIPE_MTX(rpipe), 841 PRIBIO | PCATCH, 842 "piperd", 0)) == 0) 843 error = pipelock(rpipe, 1); 844 } 845 if (error) 846 goto unlocked_error; 847 } 848 } 849 #ifdef MAC 850 locked_error: 851 #endif 852 pipeunlock(rpipe); 853 854 /* XXX: should probably do this before getting any locks. */ 855 if (error == 0) 856 pipe_timestamp(&rpipe->pipe_atime); 857 unlocked_error: 858 --rpipe->pipe_busy; 859 860 /* 861 * PIPE_WANT processing only makes sense if pipe_busy is 0. 862 */ 863 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 864 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 865 wakeup(rpipe); 866 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 867 /* 868 * Handle write blocking hysteresis. 869 */ 870 if (rpipe->pipe_state & PIPE_WANTW) { 871 rpipe->pipe_state &= ~PIPE_WANTW; 872 wakeup(rpipe); 873 } 874 } 875 876 /* 877 * Only wake up writers if there was actually something read. 878 * Otherwise, when calling read(2) at EOF, a spurious wakeup occurs. 879 */ 880 if (nread > 0 && 881 rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt >= PIPE_BUF) 882 pipeselwakeup(rpipe); 883 884 PIPE_UNLOCK(rpipe); 885 if (nread > 0) 886 td->td_ru.ru_msgrcv++; 887 return (error); 888 } 889 890 #ifndef PIPE_NODIRECT 891 /* 892 * Map the sending processes' buffer into kernel space and wire it. 893 * This is similar to a physical write operation. 894 */ 895 static int 896 pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio) 897 { 898 u_int size; 899 int i; 900 901 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 902 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0, 903 ("%s: PIPE_DIRECTW set on %p", __func__, wpipe)); 904 KASSERT(wpipe->pipe_pages.cnt == 0, 905 ("%s: pipe map for %p contains residual data", __func__, wpipe)); 906 907 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size) 908 size = wpipe->pipe_buffer.size; 909 else 910 size = uio->uio_iov->iov_len; 911 912 wpipe->pipe_state |= PIPE_DIRECTW; 913 PIPE_UNLOCK(wpipe); 914 i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 915 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ, 916 wpipe->pipe_pages.ms, PIPENPAGES); 917 PIPE_LOCK(wpipe); 918 if (i < 0) { 919 wpipe->pipe_state &= ~PIPE_DIRECTW; 920 return (EFAULT); 921 } 922 923 wpipe->pipe_pages.npages = i; 924 wpipe->pipe_pages.pos = 925 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 926 wpipe->pipe_pages.cnt = size; 927 928 uio->uio_iov->iov_len -= size; 929 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size; 930 if (uio->uio_iov->iov_len == 0) 931 uio->uio_iov++; 932 uio->uio_resid -= size; 933 uio->uio_offset += size; 934 return (0); 935 } 936 937 /* 938 * Unwire the process buffer. 939 */ 940 static void 941 pipe_destroy_write_buffer(struct pipe *wpipe) 942 { 943 944 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 945 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0, 946 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe)); 947 KASSERT(wpipe->pipe_pages.cnt == 0, 948 ("%s: pipe map for %p contains residual data", __func__, wpipe)); 949 950 wpipe->pipe_state &= ~PIPE_DIRECTW; 951 vm_page_unhold_pages(wpipe->pipe_pages.ms, wpipe->pipe_pages.npages); 952 wpipe->pipe_pages.npages = 0; 953 } 954 955 /* 956 * In the case of a signal, the writing process might go away. This 957 * code copies the data into the circular buffer so that the source 958 * pages can be freed without loss of data. 959 */ 960 static void 961 pipe_clone_write_buffer(struct pipe *wpipe) 962 { 963 struct uio uio; 964 struct iovec iov; 965 int size; 966 int pos; 967 968 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 969 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0, 970 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe)); 971 972 size = wpipe->pipe_pages.cnt; 973 pos = wpipe->pipe_pages.pos; 974 wpipe->pipe_pages.cnt = 0; 975 976 wpipe->pipe_buffer.in = size; 977 wpipe->pipe_buffer.out = 0; 978 wpipe->pipe_buffer.cnt = size; 979 980 PIPE_UNLOCK(wpipe); 981 iov.iov_base = wpipe->pipe_buffer.buffer; 982 iov.iov_len = size; 983 uio.uio_iov = &iov; 984 uio.uio_iovcnt = 1; 985 uio.uio_offset = 0; 986 uio.uio_resid = size; 987 uio.uio_segflg = UIO_SYSSPACE; 988 uio.uio_rw = UIO_READ; 989 uio.uio_td = curthread; 990 uiomove_fromphys(wpipe->pipe_pages.ms, pos, size, &uio); 991 PIPE_LOCK(wpipe); 992 pipe_destroy_write_buffer(wpipe); 993 } 994 995 /* 996 * This implements the pipe buffer write mechanism. Note that only 997 * a direct write OR a normal pipe write can be pending at any given time. 998 * If there are any characters in the pipe buffer, the direct write will 999 * be deferred until the receiving process grabs all of the bytes from 1000 * the pipe buffer. Then the direct mapping write is set-up. 1001 */ 1002 static int 1003 pipe_direct_write(struct pipe *wpipe, struct uio *uio) 1004 { 1005 int error; 1006 1007 retry: 1008 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 1009 if ((wpipe->pipe_state & PIPE_EOF) != 0) { 1010 error = EPIPE; 1011 goto error1; 1012 } 1013 if (wpipe->pipe_state & PIPE_DIRECTW) { 1014 if (wpipe->pipe_state & PIPE_WANTR) { 1015 wpipe->pipe_state &= ~PIPE_WANTR; 1016 wakeup(wpipe); 1017 } 1018 pipeselwakeup(wpipe); 1019 wpipe->pipe_state |= PIPE_WANTW; 1020 pipeunlock(wpipe); 1021 error = msleep(wpipe, PIPE_MTX(wpipe), 1022 PRIBIO | PCATCH, "pipdww", 0); 1023 pipelock(wpipe, 0); 1024 if (error != 0) 1025 goto error1; 1026 goto retry; 1027 } 1028 if (wpipe->pipe_buffer.cnt > 0) { 1029 if (wpipe->pipe_state & PIPE_WANTR) { 1030 wpipe->pipe_state &= ~PIPE_WANTR; 1031 wakeup(wpipe); 1032 } 1033 pipeselwakeup(wpipe); 1034 wpipe->pipe_state |= PIPE_WANTW; 1035 pipeunlock(wpipe); 1036 error = msleep(wpipe, PIPE_MTX(wpipe), 1037 PRIBIO | PCATCH, "pipdwc", 0); 1038 pipelock(wpipe, 0); 1039 if (error != 0) 1040 goto error1; 1041 goto retry; 1042 } 1043 1044 error = pipe_build_write_buffer(wpipe, uio); 1045 if (error) { 1046 goto error1; 1047 } 1048 1049 while (wpipe->pipe_pages.cnt != 0 && 1050 (wpipe->pipe_state & PIPE_EOF) == 0) { 1051 if (wpipe->pipe_state & PIPE_WANTR) { 1052 wpipe->pipe_state &= ~PIPE_WANTR; 1053 wakeup(wpipe); 1054 } 1055 pipeselwakeup(wpipe); 1056 wpipe->pipe_state |= PIPE_WANTW; 1057 pipeunlock(wpipe); 1058 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH, 1059 "pipdwt", 0); 1060 pipelock(wpipe, 0); 1061 if (error != 0) 1062 break; 1063 } 1064 1065 if ((wpipe->pipe_state & PIPE_EOF) != 0) { 1066 wpipe->pipe_pages.cnt = 0; 1067 pipe_destroy_write_buffer(wpipe); 1068 pipeselwakeup(wpipe); 1069 error = EPIPE; 1070 } else if (error == EINTR || error == ERESTART) { 1071 pipe_clone_write_buffer(wpipe); 1072 } else { 1073 pipe_destroy_write_buffer(wpipe); 1074 } 1075 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0, 1076 ("pipe %p leaked PIPE_DIRECTW", wpipe)); 1077 return (error); 1078 1079 error1: 1080 wakeup(wpipe); 1081 return (error); 1082 } 1083 #endif 1084 1085 static int 1086 pipe_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 1087 int flags, struct thread *td) 1088 { 1089 struct pipe *wpipe, *rpipe; 1090 ssize_t orig_resid; 1091 int desiredsize, error; 1092 1093 rpipe = fp->f_data; 1094 wpipe = PIPE_PEER(rpipe); 1095 PIPE_LOCK(rpipe); 1096 error = pipelock(wpipe, 1); 1097 if (error) { 1098 PIPE_UNLOCK(rpipe); 1099 return (error); 1100 } 1101 /* 1102 * detect loss of pipe read side, issue SIGPIPE if lost. 1103 */ 1104 if (wpipe->pipe_present != PIPE_ACTIVE || 1105 (wpipe->pipe_state & PIPE_EOF)) { 1106 pipeunlock(wpipe); 1107 PIPE_UNLOCK(rpipe); 1108 return (EPIPE); 1109 } 1110 #ifdef MAC 1111 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair); 1112 if (error) { 1113 pipeunlock(wpipe); 1114 PIPE_UNLOCK(rpipe); 1115 return (error); 1116 } 1117 #endif 1118 ++wpipe->pipe_busy; 1119 1120 /* Choose a larger size if it's advantageous */ 1121 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size); 1122 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) { 1123 if (piperesizeallowed != 1) 1124 break; 1125 if (amountpipekva > maxpipekva / 2) 1126 break; 1127 if (desiredsize == BIG_PIPE_SIZE) 1128 break; 1129 desiredsize = desiredsize * 2; 1130 } 1131 1132 /* Choose a smaller size if we're in a OOM situation */ 1133 if (amountpipekva > (3 * maxpipekva) / 4 && 1134 wpipe->pipe_buffer.size > SMALL_PIPE_SIZE && 1135 wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE && 1136 piperesizeallowed == 1) 1137 desiredsize = SMALL_PIPE_SIZE; 1138 1139 /* Resize if the above determined that a new size was necessary */ 1140 if (desiredsize != wpipe->pipe_buffer.size && 1141 (wpipe->pipe_state & PIPE_DIRECTW) == 0) { 1142 PIPE_UNLOCK(wpipe); 1143 pipespace(wpipe, desiredsize); 1144 PIPE_LOCK(wpipe); 1145 } 1146 MPASS(wpipe->pipe_buffer.size != 0); 1147 1148 orig_resid = uio->uio_resid; 1149 1150 while (uio->uio_resid) { 1151 int space; 1152 1153 if (wpipe->pipe_state & PIPE_EOF) { 1154 error = EPIPE; 1155 break; 1156 } 1157 #ifndef PIPE_NODIRECT 1158 /* 1159 * If the transfer is large, we can gain performance if 1160 * we do process-to-process copies directly. 1161 * If the write is non-blocking, we don't use the 1162 * direct write mechanism. 1163 * 1164 * The direct write mechanism will detect the reader going 1165 * away on us. 1166 */ 1167 if (uio->uio_segflg == UIO_USERSPACE && 1168 uio->uio_iov->iov_len >= pipe_mindirect && 1169 wpipe->pipe_buffer.size >= pipe_mindirect && 1170 (fp->f_flag & FNONBLOCK) == 0) { 1171 error = pipe_direct_write(wpipe, uio); 1172 if (error != 0) 1173 break; 1174 continue; 1175 } 1176 #endif 1177 1178 /* 1179 * Pipe buffered writes cannot be coincidental with 1180 * direct writes. We wait until the currently executing 1181 * direct write is completed before we start filling the 1182 * pipe buffer. We break out if a signal occurs or the 1183 * reader goes away. 1184 */ 1185 if (wpipe->pipe_pages.cnt != 0) { 1186 if (wpipe->pipe_state & PIPE_WANTR) { 1187 wpipe->pipe_state &= ~PIPE_WANTR; 1188 wakeup(wpipe); 1189 } 1190 pipeselwakeup(wpipe); 1191 wpipe->pipe_state |= PIPE_WANTW; 1192 pipeunlock(wpipe); 1193 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH, 1194 "pipbww", 0); 1195 pipelock(wpipe, 0); 1196 if (error != 0) 1197 break; 1198 continue; 1199 } 1200 1201 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1202 1203 /* Writes of size <= PIPE_BUF must be atomic. */ 1204 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 1205 space = 0; 1206 1207 if (space > 0) { 1208 int size; /* Transfer size */ 1209 int segsize; /* first segment to transfer */ 1210 1211 /* 1212 * Transfer size is minimum of uio transfer 1213 * and free space in pipe buffer. 1214 */ 1215 if (space > uio->uio_resid) 1216 size = uio->uio_resid; 1217 else 1218 size = space; 1219 /* 1220 * First segment to transfer is minimum of 1221 * transfer size and contiguous space in 1222 * pipe buffer. If first segment to transfer 1223 * is less than the transfer size, we've got 1224 * a wraparound in the buffer. 1225 */ 1226 segsize = wpipe->pipe_buffer.size - 1227 wpipe->pipe_buffer.in; 1228 if (segsize > size) 1229 segsize = size; 1230 1231 /* Transfer first segment */ 1232 1233 PIPE_UNLOCK(rpipe); 1234 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 1235 segsize, uio); 1236 PIPE_LOCK(rpipe); 1237 1238 if (error == 0 && segsize < size) { 1239 KASSERT(wpipe->pipe_buffer.in + segsize == 1240 wpipe->pipe_buffer.size, 1241 ("Pipe buffer wraparound disappeared")); 1242 /* 1243 * Transfer remaining part now, to 1244 * support atomic writes. Wraparound 1245 * happened. 1246 */ 1247 1248 PIPE_UNLOCK(rpipe); 1249 error = uiomove( 1250 &wpipe->pipe_buffer.buffer[0], 1251 size - segsize, uio); 1252 PIPE_LOCK(rpipe); 1253 } 1254 if (error == 0) { 1255 wpipe->pipe_buffer.in += size; 1256 if (wpipe->pipe_buffer.in >= 1257 wpipe->pipe_buffer.size) { 1258 KASSERT(wpipe->pipe_buffer.in == 1259 size - segsize + 1260 wpipe->pipe_buffer.size, 1261 ("Expected wraparound bad")); 1262 wpipe->pipe_buffer.in = size - segsize; 1263 } 1264 1265 wpipe->pipe_buffer.cnt += size; 1266 KASSERT(wpipe->pipe_buffer.cnt <= 1267 wpipe->pipe_buffer.size, 1268 ("Pipe buffer overflow")); 1269 } 1270 if (error != 0) 1271 break; 1272 continue; 1273 } else { 1274 /* 1275 * If the "read-side" has been blocked, wake it up now. 1276 */ 1277 if (wpipe->pipe_state & PIPE_WANTR) { 1278 wpipe->pipe_state &= ~PIPE_WANTR; 1279 wakeup(wpipe); 1280 } 1281 1282 /* 1283 * don't block on non-blocking I/O 1284 */ 1285 if (fp->f_flag & FNONBLOCK) { 1286 error = EAGAIN; 1287 break; 1288 } 1289 1290 /* 1291 * We have no more space and have something to offer, 1292 * wake up select/poll. 1293 */ 1294 pipeselwakeup(wpipe); 1295 1296 wpipe->pipe_state |= PIPE_WANTW; 1297 pipeunlock(wpipe); 1298 error = msleep(wpipe, PIPE_MTX(rpipe), 1299 PRIBIO | PCATCH, "pipewr", 0); 1300 pipelock(wpipe, 0); 1301 if (error != 0) 1302 break; 1303 continue; 1304 } 1305 } 1306 1307 --wpipe->pipe_busy; 1308 1309 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 1310 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 1311 wakeup(wpipe); 1312 } else if (wpipe->pipe_buffer.cnt > 0) { 1313 /* 1314 * If we have put any characters in the buffer, we wake up 1315 * the reader. 1316 */ 1317 if (wpipe->pipe_state & PIPE_WANTR) { 1318 wpipe->pipe_state &= ~PIPE_WANTR; 1319 wakeup(wpipe); 1320 } 1321 } 1322 1323 /* 1324 * Don't return EPIPE if any byte was written. 1325 * EINTR and other interrupts are handled by generic I/O layer. 1326 * Do not pretend that I/O succeeded for obvious user error 1327 * like EFAULT. 1328 */ 1329 if (uio->uio_resid != orig_resid && error == EPIPE) 1330 error = 0; 1331 1332 if (error == 0) 1333 pipe_timestamp(&wpipe->pipe_mtime); 1334 1335 /* 1336 * We have something to offer, 1337 * wake up select/poll. 1338 */ 1339 if (wpipe->pipe_buffer.cnt) 1340 pipeselwakeup(wpipe); 1341 1342 pipeunlock(wpipe); 1343 PIPE_UNLOCK(rpipe); 1344 if (uio->uio_resid != orig_resid) 1345 td->td_ru.ru_msgsnd++; 1346 return (error); 1347 } 1348 1349 /* ARGSUSED */ 1350 static int 1351 pipe_truncate(struct file *fp, off_t length, struct ucred *active_cred, 1352 struct thread *td) 1353 { 1354 struct pipe *cpipe; 1355 int error; 1356 1357 cpipe = fp->f_data; 1358 if (cpipe->pipe_type & PIPE_TYPE_NAMED) 1359 error = vnops.fo_truncate(fp, length, active_cred, td); 1360 else 1361 error = invfo_truncate(fp, length, active_cred, td); 1362 return (error); 1363 } 1364 1365 /* 1366 * we implement a very minimal set of ioctls for compatibility with sockets. 1367 */ 1368 static int 1369 pipe_ioctl(struct file *fp, u_long cmd, void *data, struct ucred *active_cred, 1370 struct thread *td) 1371 { 1372 struct pipe *mpipe = fp->f_data; 1373 int error; 1374 1375 PIPE_LOCK(mpipe); 1376 1377 #ifdef MAC 1378 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data); 1379 if (error) { 1380 PIPE_UNLOCK(mpipe); 1381 return (error); 1382 } 1383 #endif 1384 1385 error = 0; 1386 switch (cmd) { 1387 case FIONBIO: 1388 break; 1389 1390 case FIOASYNC: 1391 if (*(int *)data) { 1392 mpipe->pipe_state |= PIPE_ASYNC; 1393 } else { 1394 mpipe->pipe_state &= ~PIPE_ASYNC; 1395 } 1396 break; 1397 1398 case FIONREAD: 1399 if (!(fp->f_flag & FREAD)) { 1400 *(int *)data = 0; 1401 PIPE_UNLOCK(mpipe); 1402 return (0); 1403 } 1404 if (mpipe->pipe_pages.cnt != 0) 1405 *(int *)data = mpipe->pipe_pages.cnt; 1406 else 1407 *(int *)data = mpipe->pipe_buffer.cnt; 1408 break; 1409 1410 case FIOSETOWN: 1411 PIPE_UNLOCK(mpipe); 1412 error = fsetown(*(int *)data, &mpipe->pipe_sigio); 1413 goto out_unlocked; 1414 1415 case FIOGETOWN: 1416 *(int *)data = fgetown(&mpipe->pipe_sigio); 1417 break; 1418 1419 /* This is deprecated, FIOSETOWN should be used instead. */ 1420 case TIOCSPGRP: 1421 PIPE_UNLOCK(mpipe); 1422 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio); 1423 goto out_unlocked; 1424 1425 /* This is deprecated, FIOGETOWN should be used instead. */ 1426 case TIOCGPGRP: 1427 *(int *)data = -fgetown(&mpipe->pipe_sigio); 1428 break; 1429 1430 default: 1431 error = ENOTTY; 1432 break; 1433 } 1434 PIPE_UNLOCK(mpipe); 1435 out_unlocked: 1436 return (error); 1437 } 1438 1439 static int 1440 pipe_poll(struct file *fp, int events, struct ucred *active_cred, 1441 struct thread *td) 1442 { 1443 struct pipe *rpipe; 1444 struct pipe *wpipe; 1445 int levents, revents; 1446 #ifdef MAC 1447 int error; 1448 #endif 1449 1450 revents = 0; 1451 rpipe = fp->f_data; 1452 wpipe = PIPE_PEER(rpipe); 1453 PIPE_LOCK(rpipe); 1454 #ifdef MAC 1455 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair); 1456 if (error) 1457 goto locked_error; 1458 #endif 1459 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) 1460 if (rpipe->pipe_pages.cnt > 0 || rpipe->pipe_buffer.cnt > 0) 1461 revents |= events & (POLLIN | POLLRDNORM); 1462 1463 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) 1464 if (wpipe->pipe_present != PIPE_ACTIVE || 1465 (wpipe->pipe_state & PIPE_EOF) || 1466 ((wpipe->pipe_state & PIPE_DIRECTW) == 0 && 1467 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF || 1468 wpipe->pipe_buffer.size == 0))) 1469 revents |= events & (POLLOUT | POLLWRNORM); 1470 1471 levents = events & 1472 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND); 1473 if (rpipe->pipe_type & PIPE_TYPE_NAMED && fp->f_flag & FREAD && levents && 1474 fp->f_pipegen == rpipe->pipe_wgen) 1475 events |= POLLINIGNEOF; 1476 1477 if ((events & POLLINIGNEOF) == 0) { 1478 if (rpipe->pipe_state & PIPE_EOF) { 1479 if (fp->f_flag & FREAD) 1480 revents |= (events & (POLLIN | POLLRDNORM)); 1481 if (wpipe->pipe_present != PIPE_ACTIVE || 1482 (wpipe->pipe_state & PIPE_EOF)) 1483 revents |= POLLHUP; 1484 } 1485 } 1486 1487 if (revents == 0) { 1488 /* 1489 * Add ourselves regardless of eventmask as we have to return 1490 * POLLHUP even if it was not asked for. 1491 */ 1492 if ((fp->f_flag & FREAD) != 0) { 1493 selrecord(td, &rpipe->pipe_sel); 1494 if (SEL_WAITING(&rpipe->pipe_sel)) 1495 rpipe->pipe_state |= PIPE_SEL; 1496 } 1497 1498 if ((fp->f_flag & FWRITE) != 0 && 1499 wpipe->pipe_present == PIPE_ACTIVE) { 1500 selrecord(td, &wpipe->pipe_sel); 1501 if (SEL_WAITING(&wpipe->pipe_sel)) 1502 wpipe->pipe_state |= PIPE_SEL; 1503 } 1504 } 1505 #ifdef MAC 1506 locked_error: 1507 #endif 1508 PIPE_UNLOCK(rpipe); 1509 1510 return (revents); 1511 } 1512 1513 /* 1514 * We shouldn't need locks here as we're doing a read and this should 1515 * be a natural race. 1516 */ 1517 static int 1518 pipe_stat(struct file *fp, struct stat *ub, struct ucred *active_cred) 1519 { 1520 struct pipe *pipe; 1521 #ifdef MAC 1522 int error; 1523 #endif 1524 1525 pipe = fp->f_data; 1526 #ifdef MAC 1527 if (mac_pipe_check_stat_enabled()) { 1528 PIPE_LOCK(pipe); 1529 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair); 1530 PIPE_UNLOCK(pipe); 1531 if (error) { 1532 return (error); 1533 } 1534 } 1535 #endif 1536 1537 /* For named pipes ask the underlying filesystem. */ 1538 if (pipe->pipe_type & PIPE_TYPE_NAMED) { 1539 return (vnops.fo_stat(fp, ub, active_cred)); 1540 } 1541 1542 bzero(ub, sizeof(*ub)); 1543 ub->st_mode = S_IFIFO; 1544 ub->st_blksize = PAGE_SIZE; 1545 if (pipe->pipe_pages.cnt != 0) 1546 ub->st_size = pipe->pipe_pages.cnt; 1547 else 1548 ub->st_size = pipe->pipe_buffer.cnt; 1549 ub->st_blocks = howmany(ub->st_size, ub->st_blksize); 1550 ub->st_atim = pipe->pipe_atime; 1551 ub->st_mtim = pipe->pipe_mtime; 1552 ub->st_ctim = pipe->pipe_ctime; 1553 ub->st_uid = fp->f_cred->cr_uid; 1554 ub->st_gid = fp->f_cred->cr_gid; 1555 ub->st_dev = pipedev_ino; 1556 ub->st_ino = pipe->pipe_ino; 1557 /* 1558 * Left as 0: st_nlink, st_rdev, st_flags, st_gen. 1559 */ 1560 return (0); 1561 } 1562 1563 /* ARGSUSED */ 1564 static int 1565 pipe_close(struct file *fp, struct thread *td) 1566 { 1567 1568 if (fp->f_vnode != NULL) 1569 return vnops.fo_close(fp, td); 1570 fp->f_ops = &badfileops; 1571 pipe_dtor(fp->f_data); 1572 fp->f_data = NULL; 1573 return (0); 1574 } 1575 1576 static int 1577 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td) 1578 { 1579 struct pipe *cpipe; 1580 int error; 1581 1582 cpipe = fp->f_data; 1583 if (cpipe->pipe_type & PIPE_TYPE_NAMED) 1584 error = vn_chmod(fp, mode, active_cred, td); 1585 else 1586 error = invfo_chmod(fp, mode, active_cred, td); 1587 return (error); 1588 } 1589 1590 static int 1591 pipe_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1592 struct thread *td) 1593 { 1594 struct pipe *cpipe; 1595 int error; 1596 1597 cpipe = fp->f_data; 1598 if (cpipe->pipe_type & PIPE_TYPE_NAMED) 1599 error = vn_chown(fp, uid, gid, active_cred, td); 1600 else 1601 error = invfo_chown(fp, uid, gid, active_cred, td); 1602 return (error); 1603 } 1604 1605 static int 1606 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp) 1607 { 1608 struct pipe *pi; 1609 1610 if (fp->f_type == DTYPE_FIFO) 1611 return (vn_fill_kinfo(fp, kif, fdp)); 1612 kif->kf_type = KF_TYPE_PIPE; 1613 pi = fp->f_data; 1614 kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi; 1615 kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer; 1616 kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt; 1617 return (0); 1618 } 1619 1620 static void 1621 pipe_free_kmem(struct pipe *cpipe) 1622 { 1623 1624 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), 1625 ("pipe_free_kmem: pipe mutex locked")); 1626 1627 if (cpipe->pipe_buffer.buffer != NULL) { 1628 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size); 1629 vm_map_remove(pipe_map, 1630 (vm_offset_t)cpipe->pipe_buffer.buffer, 1631 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size); 1632 cpipe->pipe_buffer.buffer = NULL; 1633 } 1634 #ifndef PIPE_NODIRECT 1635 { 1636 cpipe->pipe_pages.cnt = 0; 1637 cpipe->pipe_pages.pos = 0; 1638 cpipe->pipe_pages.npages = 0; 1639 } 1640 #endif 1641 } 1642 1643 /* 1644 * shutdown the pipe 1645 */ 1646 static void 1647 pipeclose(struct pipe *cpipe) 1648 { 1649 struct pipepair *pp; 1650 struct pipe *ppipe; 1651 1652 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL")); 1653 1654 PIPE_LOCK(cpipe); 1655 pipelock(cpipe, 0); 1656 pp = cpipe->pipe_pair; 1657 1658 /* 1659 * If the other side is blocked, wake it up saying that 1660 * we want to close it down. 1661 */ 1662 cpipe->pipe_state |= PIPE_EOF; 1663 while (cpipe->pipe_busy) { 1664 wakeup(cpipe); 1665 cpipe->pipe_state |= PIPE_WANT; 1666 pipeunlock(cpipe); 1667 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0); 1668 pipelock(cpipe, 0); 1669 } 1670 1671 pipeselwakeup(cpipe); 1672 1673 /* 1674 * Disconnect from peer, if any. 1675 */ 1676 ppipe = cpipe->pipe_peer; 1677 if (ppipe->pipe_present == PIPE_ACTIVE) { 1678 ppipe->pipe_state |= PIPE_EOF; 1679 wakeup(ppipe); 1680 pipeselwakeup(ppipe); 1681 } 1682 1683 /* 1684 * Mark this endpoint as free. Release kmem resources. We 1685 * don't mark this endpoint as unused until we've finished 1686 * doing that, or the pipe might disappear out from under 1687 * us. 1688 */ 1689 PIPE_UNLOCK(cpipe); 1690 pipe_free_kmem(cpipe); 1691 PIPE_LOCK(cpipe); 1692 cpipe->pipe_present = PIPE_CLOSING; 1693 pipeunlock(cpipe); 1694 1695 /* 1696 * knlist_clear() may sleep dropping the PIPE_MTX. Set the 1697 * PIPE_FINALIZED, that allows other end to free the 1698 * pipe_pair, only after the knotes are completely dismantled. 1699 */ 1700 knlist_clear(&cpipe->pipe_sel.si_note, 1); 1701 cpipe->pipe_present = PIPE_FINALIZED; 1702 seldrain(&cpipe->pipe_sel); 1703 knlist_destroy(&cpipe->pipe_sel.si_note); 1704 1705 /* 1706 * If both endpoints are now closed, release the memory for the 1707 * pipe pair. If not, unlock. 1708 */ 1709 if (ppipe->pipe_present == PIPE_FINALIZED) { 1710 PIPE_UNLOCK(cpipe); 1711 #ifdef MAC 1712 mac_pipe_destroy(pp); 1713 #endif 1714 uma_zfree(pipe_zone, cpipe->pipe_pair); 1715 } else 1716 PIPE_UNLOCK(cpipe); 1717 } 1718 1719 /*ARGSUSED*/ 1720 static int 1721 pipe_kqfilter(struct file *fp, struct knote *kn) 1722 { 1723 struct pipe *cpipe; 1724 1725 /* 1726 * If a filter is requested that is not supported by this file 1727 * descriptor, don't return an error, but also don't ever generate an 1728 * event. 1729 */ 1730 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) { 1731 kn->kn_fop = &pipe_nfiltops; 1732 return (0); 1733 } 1734 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) { 1735 kn->kn_fop = &pipe_nfiltops; 1736 return (0); 1737 } 1738 cpipe = fp->f_data; 1739 PIPE_LOCK(cpipe); 1740 switch (kn->kn_filter) { 1741 case EVFILT_READ: 1742 kn->kn_fop = &pipe_rfiltops; 1743 break; 1744 case EVFILT_WRITE: 1745 kn->kn_fop = &pipe_wfiltops; 1746 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) { 1747 /* other end of pipe has been closed */ 1748 PIPE_UNLOCK(cpipe); 1749 return (EPIPE); 1750 } 1751 cpipe = PIPE_PEER(cpipe); 1752 break; 1753 default: 1754 if ((cpipe->pipe_type & PIPE_TYPE_NAMED) != 0) { 1755 PIPE_UNLOCK(cpipe); 1756 return (vnops.fo_kqfilter(fp, kn)); 1757 } 1758 PIPE_UNLOCK(cpipe); 1759 return (EINVAL); 1760 } 1761 1762 kn->kn_hook = cpipe; 1763 knlist_add(&cpipe->pipe_sel.si_note, kn, 1); 1764 PIPE_UNLOCK(cpipe); 1765 return (0); 1766 } 1767 1768 static void 1769 filt_pipedetach(struct knote *kn) 1770 { 1771 struct pipe *cpipe = kn->kn_hook; 1772 1773 PIPE_LOCK(cpipe); 1774 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1); 1775 PIPE_UNLOCK(cpipe); 1776 } 1777 1778 /*ARGSUSED*/ 1779 static int 1780 filt_piperead(struct knote *kn, long hint) 1781 { 1782 struct file *fp = kn->kn_fp; 1783 struct pipe *rpipe = kn->kn_hook; 1784 1785 PIPE_LOCK_ASSERT(rpipe, MA_OWNED); 1786 kn->kn_data = rpipe->pipe_buffer.cnt; 1787 if (kn->kn_data == 0) 1788 kn->kn_data = rpipe->pipe_pages.cnt; 1789 1790 if ((rpipe->pipe_state & PIPE_EOF) != 0 && 1791 ((rpipe->pipe_type & PIPE_TYPE_NAMED) == 0 || 1792 fp->f_pipegen != rpipe->pipe_wgen)) { 1793 kn->kn_flags |= EV_EOF; 1794 return (1); 1795 } 1796 kn->kn_flags &= ~EV_EOF; 1797 return (kn->kn_data > 0); 1798 } 1799 1800 /*ARGSUSED*/ 1801 static int 1802 filt_pipewrite(struct knote *kn, long hint) 1803 { 1804 struct pipe *wpipe = kn->kn_hook; 1805 1806 /* 1807 * If this end of the pipe is closed, the knote was removed from the 1808 * knlist and the list lock (i.e., the pipe lock) is therefore not held. 1809 */ 1810 if (wpipe->pipe_present == PIPE_ACTIVE || 1811 (wpipe->pipe_type & PIPE_TYPE_NAMED) != 0) { 1812 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 1813 1814 if (wpipe->pipe_state & PIPE_DIRECTW) { 1815 kn->kn_data = 0; 1816 } else if (wpipe->pipe_buffer.size > 0) { 1817 kn->kn_data = wpipe->pipe_buffer.size - 1818 wpipe->pipe_buffer.cnt; 1819 } else { 1820 kn->kn_data = PIPE_BUF; 1821 } 1822 } 1823 1824 if (wpipe->pipe_present != PIPE_ACTIVE || 1825 (wpipe->pipe_state & PIPE_EOF)) { 1826 kn->kn_flags |= EV_EOF; 1827 return (1); 1828 } 1829 kn->kn_flags &= ~EV_EOF; 1830 return (kn->kn_data >= PIPE_BUF); 1831 } 1832 1833 static void 1834 filt_pipedetach_notsup(struct knote *kn) 1835 { 1836 1837 } 1838 1839 static int 1840 filt_pipenotsup(struct knote *kn, long hint) 1841 { 1842 1843 return (0); 1844 } 1845