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; 212 213 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, 214 &maxpipekva, 0, "Pipe KVA limit"); 215 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD, 216 &amountpipekva, 0, "Pipe KVA usage"); 217 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD, 218 &pipefragretry, 0, "Pipe allocation retries due to fragmentation"); 219 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD, 220 &pipeallocfail, 0, "Pipe allocation failures"); 221 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD, 222 &piperesizefail, 0, "Pipe resize failures"); 223 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW, 224 &piperesizeallowed, 0, "Pipe resizing allowed"); 225 226 static void pipeinit(void *dummy __unused); 227 static void pipeclose(struct pipe *cpipe); 228 static void pipe_free_kmem(struct pipe *cpipe); 229 static int pipe_create(struct pipe *pipe, bool backing); 230 static int pipe_paircreate(struct thread *td, struct pipepair **p_pp); 231 static __inline int pipelock(struct pipe *cpipe, int catch); 232 static __inline void pipeunlock(struct pipe *cpipe); 233 static void pipe_timestamp(struct timespec *tsp); 234 #ifndef PIPE_NODIRECT 235 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio); 236 static void pipe_destroy_write_buffer(struct pipe *wpipe); 237 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio); 238 static void pipe_clone_write_buffer(struct pipe *wpipe); 239 #endif 240 static int pipespace(struct pipe *cpipe, int size); 241 static int pipespace_new(struct pipe *cpipe, int size); 242 243 static int pipe_zone_ctor(void *mem, int size, void *arg, int flags); 244 static int pipe_zone_init(void *mem, int size, int flags); 245 static void pipe_zone_fini(void *mem, int size); 246 247 static uma_zone_t pipe_zone; 248 static struct unrhdr64 pipeino_unr; 249 static dev_t pipedev_ino; 250 251 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL); 252 253 static void 254 pipeinit(void *dummy __unused) 255 { 256 257 pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair), 258 pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini, 259 UMA_ALIGN_PTR, 0); 260 KASSERT(pipe_zone != NULL, ("pipe_zone not initialized")); 261 new_unrhdr64(&pipeino_unr, 1); 262 pipedev_ino = devfs_alloc_cdp_inode(); 263 KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized")); 264 } 265 266 static int 267 pipe_zone_ctor(void *mem, int size, void *arg, int flags) 268 { 269 struct pipepair *pp; 270 struct pipe *rpipe, *wpipe; 271 272 KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size")); 273 274 pp = (struct pipepair *)mem; 275 276 /* 277 * We zero both pipe endpoints to make sure all the kmem pointers 278 * are NULL, flag fields are zero'd, etc. We timestamp both 279 * endpoints with the same time. 280 */ 281 rpipe = &pp->pp_rpipe; 282 bzero(rpipe, sizeof(*rpipe)); 283 pipe_timestamp(&rpipe->pipe_ctime); 284 rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime; 285 286 wpipe = &pp->pp_wpipe; 287 bzero(wpipe, sizeof(*wpipe)); 288 wpipe->pipe_ctime = rpipe->pipe_ctime; 289 wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime; 290 291 rpipe->pipe_peer = wpipe; 292 rpipe->pipe_pair = pp; 293 wpipe->pipe_peer = rpipe; 294 wpipe->pipe_pair = pp; 295 296 /* 297 * Mark both endpoints as present; they will later get free'd 298 * one at a time. When both are free'd, then the whole pair 299 * is released. 300 */ 301 rpipe->pipe_present = PIPE_ACTIVE; 302 wpipe->pipe_present = PIPE_ACTIVE; 303 304 /* 305 * Eventually, the MAC Framework may initialize the label 306 * in ctor or init, but for now we do it elswhere to avoid 307 * blocking in ctor or init. 308 */ 309 pp->pp_label = NULL; 310 311 return (0); 312 } 313 314 static int 315 pipe_zone_init(void *mem, int size, int flags) 316 { 317 struct pipepair *pp; 318 319 KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size")); 320 321 pp = (struct pipepair *)mem; 322 323 mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_NEW); 324 return (0); 325 } 326 327 static void 328 pipe_zone_fini(void *mem, int size) 329 { 330 struct pipepair *pp; 331 332 KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size")); 333 334 pp = (struct pipepair *)mem; 335 336 mtx_destroy(&pp->pp_mtx); 337 } 338 339 static int 340 pipe_paircreate(struct thread *td, struct pipepair **p_pp) 341 { 342 struct pipepair *pp; 343 struct pipe *rpipe, *wpipe; 344 int error; 345 346 *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK); 347 #ifdef MAC 348 /* 349 * The MAC label is shared between the connected endpoints. As a 350 * result mac_pipe_init() and mac_pipe_create() are called once 351 * for the pair, and not on the endpoints. 352 */ 353 mac_pipe_init(pp); 354 mac_pipe_create(td->td_ucred, pp); 355 #endif 356 rpipe = &pp->pp_rpipe; 357 wpipe = &pp->pp_wpipe; 358 359 knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe)); 360 knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe)); 361 362 /* 363 * Only the forward direction pipe is backed by big buffer by 364 * default. 365 */ 366 error = pipe_create(rpipe, true); 367 if (error != 0) 368 goto fail; 369 error = pipe_create(wpipe, false); 370 if (error != 0) { 371 /* 372 * This cleanup leaves the pipe inode number for rpipe 373 * still allocated, but never used. We do not free 374 * inode numbers for opened pipes, which is required 375 * for correctness because numbers must be unique. 376 * But also it avoids any memory use by the unr 377 * allocator, so stashing away the transient inode 378 * number is reasonable. 379 */ 380 pipe_free_kmem(rpipe); 381 goto fail; 382 } 383 384 rpipe->pipe_state |= PIPE_DIRECTOK; 385 wpipe->pipe_state |= PIPE_DIRECTOK; 386 return (0); 387 388 fail: 389 knlist_destroy(&rpipe->pipe_sel.si_note); 390 knlist_destroy(&wpipe->pipe_sel.si_note); 391 #ifdef MAC 392 mac_pipe_destroy(pp); 393 #endif 394 return (error); 395 } 396 397 int 398 pipe_named_ctor(struct pipe **ppipe, struct thread *td) 399 { 400 struct pipepair *pp; 401 int error; 402 403 error = pipe_paircreate(td, &pp); 404 if (error != 0) 405 return (error); 406 pp->pp_rpipe.pipe_type |= PIPE_TYPE_NAMED; 407 *ppipe = &pp->pp_rpipe; 408 return (0); 409 } 410 411 void 412 pipe_dtor(struct pipe *dpipe) 413 { 414 struct pipe *peer; 415 416 peer = (dpipe->pipe_type & PIPE_TYPE_NAMED) != 0 ? dpipe->pipe_peer : NULL; 417 funsetown(&dpipe->pipe_sigio); 418 pipeclose(dpipe); 419 if (peer != NULL) { 420 funsetown(&peer->pipe_sigio); 421 pipeclose(peer); 422 } 423 } 424 425 /* 426 * Get a timestamp. 427 * 428 * This used to be vfs_timestamp but the higher precision is unnecessary and 429 * can very negatively affect performance in virtualized environments (e.g., on 430 * vms running on amd64 when using the rdtscp instruction). 431 */ 432 static void 433 pipe_timestamp(struct timespec *tsp) 434 { 435 436 getnanotime(tsp); 437 } 438 439 /* 440 * The pipe system call for the DTYPE_PIPE type of pipes. If we fail, let 441 * the zone pick up the pieces via pipeclose(). 442 */ 443 int 444 kern_pipe(struct thread *td, int fildes[2], int flags, struct filecaps *fcaps1, 445 struct filecaps *fcaps2) 446 { 447 struct file *rf, *wf; 448 struct pipe *rpipe, *wpipe; 449 struct pipepair *pp; 450 int fd, fflags, error; 451 452 error = pipe_paircreate(td, &pp); 453 if (error != 0) 454 return (error); 455 rpipe = &pp->pp_rpipe; 456 wpipe = &pp->pp_wpipe; 457 error = falloc_caps(td, &rf, &fd, flags, fcaps1); 458 if (error) { 459 pipeclose(rpipe); 460 pipeclose(wpipe); 461 return (error); 462 } 463 /* An extra reference on `rf' has been held for us by falloc_caps(). */ 464 fildes[0] = fd; 465 466 fflags = FREAD | FWRITE; 467 if ((flags & O_NONBLOCK) != 0) 468 fflags |= FNONBLOCK; 469 470 /* 471 * Warning: once we've gotten past allocation of the fd for the 472 * read-side, we can only drop the read side via fdrop() in order 473 * to avoid races against processes which manage to dup() the read 474 * side while we are blocked trying to allocate the write side. 475 */ 476 finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops); 477 error = falloc_caps(td, &wf, &fd, flags, fcaps2); 478 if (error) { 479 fdclose(td, rf, fildes[0]); 480 fdrop(rf, td); 481 /* rpipe has been closed by fdrop(). */ 482 pipeclose(wpipe); 483 return (error); 484 } 485 /* An extra reference on `wf' has been held for us by falloc_caps(). */ 486 finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops); 487 fdrop(wf, td); 488 fildes[1] = fd; 489 fdrop(rf, td); 490 491 return (0); 492 } 493 494 #ifdef COMPAT_FREEBSD10 495 /* ARGSUSED */ 496 int 497 freebsd10_pipe(struct thread *td, struct freebsd10_pipe_args *uap __unused) 498 { 499 int error; 500 int fildes[2]; 501 502 error = kern_pipe(td, fildes, 0, NULL, NULL); 503 if (error) 504 return (error); 505 506 td->td_retval[0] = fildes[0]; 507 td->td_retval[1] = fildes[1]; 508 509 return (0); 510 } 511 #endif 512 513 int 514 sys_pipe2(struct thread *td, struct pipe2_args *uap) 515 { 516 int error, fildes[2]; 517 518 if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK)) 519 return (EINVAL); 520 error = kern_pipe(td, fildes, uap->flags, NULL, NULL); 521 if (error) 522 return (error); 523 error = copyout(fildes, uap->fildes, 2 * sizeof(int)); 524 if (error) { 525 (void)kern_close(td, fildes[0]); 526 (void)kern_close(td, fildes[1]); 527 } 528 return (error); 529 } 530 531 /* 532 * Allocate kva for pipe circular buffer, the space is pageable 533 * This routine will 'realloc' the size of a pipe safely, if it fails 534 * it will retain the old buffer. 535 * If it fails it will return ENOMEM. 536 */ 537 static int 538 pipespace_new(struct pipe *cpipe, int size) 539 { 540 caddr_t buffer; 541 int error, cnt, firstseg; 542 static int curfail = 0; 543 static struct timeval lastfail; 544 545 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked")); 546 KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW), 547 ("pipespace: resize of direct writes not allowed")); 548 retry: 549 cnt = cpipe->pipe_buffer.cnt; 550 if (cnt > size) 551 size = cnt; 552 553 size = round_page(size); 554 buffer = (caddr_t) vm_map_min(pipe_map); 555 556 error = vm_map_find(pipe_map, NULL, 0, (vm_offset_t *)&buffer, size, 0, 557 VMFS_ANY_SPACE, VM_PROT_RW, VM_PROT_RW, 0); 558 if (error != KERN_SUCCESS) { 559 if (cpipe->pipe_buffer.buffer == NULL && 560 size > SMALL_PIPE_SIZE) { 561 size = SMALL_PIPE_SIZE; 562 pipefragretry++; 563 goto retry; 564 } 565 if (cpipe->pipe_buffer.buffer == NULL) { 566 pipeallocfail++; 567 if (ppsratecheck(&lastfail, &curfail, 1)) 568 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n"); 569 } else { 570 piperesizefail++; 571 } 572 return (ENOMEM); 573 } 574 575 /* copy data, then free old resources if we're resizing */ 576 if (cnt > 0) { 577 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) { 578 firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out; 579 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 580 buffer, firstseg); 581 if ((cnt - firstseg) > 0) 582 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg], 583 cpipe->pipe_buffer.in); 584 } else { 585 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 586 buffer, cnt); 587 } 588 } 589 pipe_free_kmem(cpipe); 590 cpipe->pipe_buffer.buffer = buffer; 591 cpipe->pipe_buffer.size = size; 592 cpipe->pipe_buffer.in = cnt; 593 cpipe->pipe_buffer.out = 0; 594 cpipe->pipe_buffer.cnt = cnt; 595 atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size); 596 return (0); 597 } 598 599 /* 600 * Wrapper for pipespace_new() that performs locking assertions. 601 */ 602 static int 603 pipespace(struct pipe *cpipe, int size) 604 { 605 606 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 607 ("Unlocked pipe passed to pipespace")); 608 return (pipespace_new(cpipe, size)); 609 } 610 611 /* 612 * lock a pipe for I/O, blocking other access 613 */ 614 static __inline int 615 pipelock(struct pipe *cpipe, int catch) 616 { 617 int error, prio; 618 619 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 620 621 prio = PRIBIO; 622 if (catch) 623 prio |= PCATCH; 624 while (cpipe->pipe_state & PIPE_LOCKFL) { 625 KASSERT(cpipe->pipe_waiters >= 0, 626 ("%s: bad waiter count %d", __func__, 627 cpipe->pipe_waiters)); 628 cpipe->pipe_waiters++; 629 error = msleep(cpipe, PIPE_MTX(cpipe), 630 prio, "pipelk", 0); 631 cpipe->pipe_waiters--; 632 if (error != 0) 633 return (error); 634 } 635 cpipe->pipe_state |= PIPE_LOCKFL; 636 return (0); 637 } 638 639 /* 640 * unlock a pipe I/O lock 641 */ 642 static __inline void 643 pipeunlock(struct pipe *cpipe) 644 { 645 646 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 647 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 648 ("Unlocked pipe passed to pipeunlock")); 649 KASSERT(cpipe->pipe_waiters >= 0, 650 ("%s: bad waiter count %d", __func__, 651 cpipe->pipe_waiters)); 652 cpipe->pipe_state &= ~PIPE_LOCKFL; 653 if (cpipe->pipe_waiters > 0) { 654 wakeup_one(cpipe); 655 } 656 } 657 658 void 659 pipeselwakeup(struct pipe *cpipe) 660 { 661 662 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 663 if (cpipe->pipe_state & PIPE_SEL) { 664 selwakeuppri(&cpipe->pipe_sel, PSOCK); 665 if (!SEL_WAITING(&cpipe->pipe_sel)) 666 cpipe->pipe_state &= ~PIPE_SEL; 667 } 668 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) 669 pgsigio(&cpipe->pipe_sigio, SIGIO, 0); 670 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0); 671 } 672 673 /* 674 * Initialize and allocate VM and memory for pipe. The structure 675 * will start out zero'd from the ctor, so we just manage the kmem. 676 */ 677 static int 678 pipe_create(struct pipe *pipe, bool large_backing) 679 { 680 int error; 681 682 error = pipespace_new(pipe, !large_backing || amountpipekva > 683 maxpipekva / 2 ? SMALL_PIPE_SIZE : PIPE_SIZE); 684 if (error == 0) 685 pipe->pipe_ino = alloc_unr64(&pipeino_unr); 686 return (error); 687 } 688 689 /* ARGSUSED */ 690 static int 691 pipe_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 692 int flags, struct thread *td) 693 { 694 struct pipe *rpipe; 695 int error; 696 int nread = 0; 697 int size; 698 699 rpipe = fp->f_data; 700 PIPE_LOCK(rpipe); 701 ++rpipe->pipe_busy; 702 error = pipelock(rpipe, 1); 703 if (error) 704 goto unlocked_error; 705 706 #ifdef MAC 707 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair); 708 if (error) 709 goto locked_error; 710 #endif 711 if (amountpipekva > (3 * maxpipekva) / 4) { 712 if ((rpipe->pipe_state & PIPE_DIRECTW) == 0 && 713 rpipe->pipe_buffer.size > SMALL_PIPE_SIZE && 714 rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE && 715 piperesizeallowed == 1) { 716 PIPE_UNLOCK(rpipe); 717 pipespace(rpipe, SMALL_PIPE_SIZE); 718 PIPE_LOCK(rpipe); 719 } 720 } 721 722 while (uio->uio_resid) { 723 /* 724 * normal pipe buffer receive 725 */ 726 if (rpipe->pipe_buffer.cnt > 0) { 727 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 728 if (size > rpipe->pipe_buffer.cnt) 729 size = rpipe->pipe_buffer.cnt; 730 if (size > uio->uio_resid) 731 size = uio->uio_resid; 732 733 PIPE_UNLOCK(rpipe); 734 error = uiomove( 735 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 736 size, uio); 737 PIPE_LOCK(rpipe); 738 if (error) 739 break; 740 741 rpipe->pipe_buffer.out += size; 742 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 743 rpipe->pipe_buffer.out = 0; 744 745 rpipe->pipe_buffer.cnt -= size; 746 747 /* 748 * If there is no more to read in the pipe, reset 749 * its pointers to the beginning. This improves 750 * cache hit stats. 751 */ 752 if (rpipe->pipe_buffer.cnt == 0) { 753 rpipe->pipe_buffer.in = 0; 754 rpipe->pipe_buffer.out = 0; 755 } 756 nread += size; 757 #ifndef PIPE_NODIRECT 758 /* 759 * Direct copy, bypassing a kernel buffer. 760 */ 761 } else if ((size = rpipe->pipe_pages.cnt) != 0) { 762 if (size > uio->uio_resid) 763 size = (u_int) uio->uio_resid; 764 PIPE_UNLOCK(rpipe); 765 error = uiomove_fromphys(rpipe->pipe_pages.ms, 766 rpipe->pipe_pages.pos, size, uio); 767 PIPE_LOCK(rpipe); 768 if (error) 769 break; 770 nread += size; 771 rpipe->pipe_pages.pos += size; 772 rpipe->pipe_pages.cnt -= size; 773 if (rpipe->pipe_pages.cnt == 0) { 774 rpipe->pipe_state &= ~PIPE_WANTW; 775 wakeup(rpipe); 776 } 777 #endif 778 } else { 779 /* 780 * detect EOF condition 781 * read returns 0 on EOF, no need to set error 782 */ 783 if (rpipe->pipe_state & PIPE_EOF) 784 break; 785 786 /* 787 * If the "write-side" has been blocked, wake it up now. 788 */ 789 if (rpipe->pipe_state & PIPE_WANTW) { 790 rpipe->pipe_state &= ~PIPE_WANTW; 791 wakeup(rpipe); 792 } 793 794 /* 795 * Break if some data was read. 796 */ 797 if (nread > 0) 798 break; 799 800 /* 801 * Unlock the pipe buffer for our remaining processing. 802 * We will either break out with an error or we will 803 * sleep and relock to loop. 804 */ 805 pipeunlock(rpipe); 806 807 /* 808 * Handle non-blocking mode operation or 809 * wait for more data. 810 */ 811 if (fp->f_flag & FNONBLOCK) { 812 error = EAGAIN; 813 } else { 814 rpipe->pipe_state |= PIPE_WANTR; 815 if ((error = msleep(rpipe, PIPE_MTX(rpipe), 816 PRIBIO | PCATCH, 817 "piperd", 0)) == 0) 818 error = pipelock(rpipe, 1); 819 } 820 if (error) 821 goto unlocked_error; 822 } 823 } 824 #ifdef MAC 825 locked_error: 826 #endif 827 pipeunlock(rpipe); 828 829 /* XXX: should probably do this before getting any locks. */ 830 if (error == 0) 831 pipe_timestamp(&rpipe->pipe_atime); 832 unlocked_error: 833 --rpipe->pipe_busy; 834 835 /* 836 * PIPE_WANT processing only makes sense if pipe_busy is 0. 837 */ 838 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 839 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 840 wakeup(rpipe); 841 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 842 /* 843 * Handle write blocking hysteresis. 844 */ 845 if (rpipe->pipe_state & PIPE_WANTW) { 846 rpipe->pipe_state &= ~PIPE_WANTW; 847 wakeup(rpipe); 848 } 849 } 850 851 /* 852 * Only wake up writers if there was actually something read. 853 * Otherwise, when calling read(2) at EOF, a spurious wakeup occurs. 854 */ 855 if (nread > 0 && 856 rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt >= PIPE_BUF) 857 pipeselwakeup(rpipe); 858 859 PIPE_UNLOCK(rpipe); 860 return (error); 861 } 862 863 #ifndef PIPE_NODIRECT 864 /* 865 * Map the sending processes' buffer into kernel space and wire it. 866 * This is similar to a physical write operation. 867 */ 868 static int 869 pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio) 870 { 871 u_int size; 872 int i; 873 874 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 875 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0, 876 ("%s: PIPE_DIRECTW set on %p", __func__, wpipe)); 877 KASSERT(wpipe->pipe_pages.cnt == 0, 878 ("%s: pipe map for %p contains residual data", __func__, wpipe)); 879 880 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size) 881 size = wpipe->pipe_buffer.size; 882 else 883 size = uio->uio_iov->iov_len; 884 885 wpipe->pipe_state |= PIPE_DIRECTW; 886 PIPE_UNLOCK(wpipe); 887 i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 888 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ, 889 wpipe->pipe_pages.ms, PIPENPAGES); 890 PIPE_LOCK(wpipe); 891 if (i < 0) { 892 wpipe->pipe_state &= ~PIPE_DIRECTW; 893 return (EFAULT); 894 } 895 896 wpipe->pipe_pages.npages = i; 897 wpipe->pipe_pages.pos = 898 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 899 wpipe->pipe_pages.cnt = size; 900 901 uio->uio_iov->iov_len -= size; 902 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size; 903 if (uio->uio_iov->iov_len == 0) 904 uio->uio_iov++; 905 uio->uio_resid -= size; 906 uio->uio_offset += size; 907 return (0); 908 } 909 910 /* 911 * Unwire the process buffer. 912 */ 913 static void 914 pipe_destroy_write_buffer(struct pipe *wpipe) 915 { 916 917 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 918 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0, 919 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe)); 920 KASSERT(wpipe->pipe_pages.cnt == 0, 921 ("%s: pipe map for %p contains residual data", __func__, wpipe)); 922 923 wpipe->pipe_state &= ~PIPE_DIRECTW; 924 vm_page_unhold_pages(wpipe->pipe_pages.ms, wpipe->pipe_pages.npages); 925 wpipe->pipe_pages.npages = 0; 926 } 927 928 /* 929 * In the case of a signal, the writing process might go away. This 930 * code copies the data into the circular buffer so that the source 931 * pages can be freed without loss of data. 932 */ 933 static void 934 pipe_clone_write_buffer(struct pipe *wpipe) 935 { 936 struct uio uio; 937 struct iovec iov; 938 int size; 939 int pos; 940 941 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 942 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0, 943 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe)); 944 945 size = wpipe->pipe_pages.cnt; 946 pos = wpipe->pipe_pages.pos; 947 wpipe->pipe_pages.cnt = 0; 948 949 wpipe->pipe_buffer.in = size; 950 wpipe->pipe_buffer.out = 0; 951 wpipe->pipe_buffer.cnt = size; 952 953 PIPE_UNLOCK(wpipe); 954 iov.iov_base = wpipe->pipe_buffer.buffer; 955 iov.iov_len = size; 956 uio.uio_iov = &iov; 957 uio.uio_iovcnt = 1; 958 uio.uio_offset = 0; 959 uio.uio_resid = size; 960 uio.uio_segflg = UIO_SYSSPACE; 961 uio.uio_rw = UIO_READ; 962 uio.uio_td = curthread; 963 uiomove_fromphys(wpipe->pipe_pages.ms, pos, size, &uio); 964 PIPE_LOCK(wpipe); 965 pipe_destroy_write_buffer(wpipe); 966 } 967 968 /* 969 * This implements the pipe buffer write mechanism. Note that only 970 * a direct write OR a normal pipe write can be pending at any given time. 971 * If there are any characters in the pipe buffer, the direct write will 972 * be deferred until the receiving process grabs all of the bytes from 973 * the pipe buffer. Then the direct mapping write is set-up. 974 */ 975 static int 976 pipe_direct_write(struct pipe *wpipe, struct uio *uio) 977 { 978 int error; 979 980 retry: 981 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 982 if ((wpipe->pipe_state & PIPE_EOF) != 0) { 983 error = EPIPE; 984 goto error1; 985 } 986 if (wpipe->pipe_state & PIPE_DIRECTW) { 987 if (wpipe->pipe_state & PIPE_WANTR) { 988 wpipe->pipe_state &= ~PIPE_WANTR; 989 wakeup(wpipe); 990 } 991 pipeselwakeup(wpipe); 992 wpipe->pipe_state |= PIPE_WANTW; 993 pipeunlock(wpipe); 994 error = msleep(wpipe, PIPE_MTX(wpipe), 995 PRIBIO | PCATCH, "pipdww", 0); 996 pipelock(wpipe, 0); 997 if (error != 0) 998 goto error1; 999 goto retry; 1000 } 1001 if (wpipe->pipe_buffer.cnt > 0) { 1002 if (wpipe->pipe_state & PIPE_WANTR) { 1003 wpipe->pipe_state &= ~PIPE_WANTR; 1004 wakeup(wpipe); 1005 } 1006 pipeselwakeup(wpipe); 1007 wpipe->pipe_state |= PIPE_WANTW; 1008 pipeunlock(wpipe); 1009 error = msleep(wpipe, PIPE_MTX(wpipe), 1010 PRIBIO | PCATCH, "pipdwc", 0); 1011 pipelock(wpipe, 0); 1012 if (error != 0) 1013 goto error1; 1014 goto retry; 1015 } 1016 1017 error = pipe_build_write_buffer(wpipe, uio); 1018 if (error) { 1019 goto error1; 1020 } 1021 1022 while (wpipe->pipe_pages.cnt != 0 && 1023 (wpipe->pipe_state & PIPE_EOF) == 0) { 1024 if (wpipe->pipe_state & PIPE_WANTR) { 1025 wpipe->pipe_state &= ~PIPE_WANTR; 1026 wakeup(wpipe); 1027 } 1028 pipeselwakeup(wpipe); 1029 wpipe->pipe_state |= PIPE_WANTW; 1030 pipeunlock(wpipe); 1031 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH, 1032 "pipdwt", 0); 1033 pipelock(wpipe, 0); 1034 if (error != 0) 1035 break; 1036 } 1037 1038 if ((wpipe->pipe_state & PIPE_EOF) != 0) { 1039 wpipe->pipe_pages.cnt = 0; 1040 pipe_destroy_write_buffer(wpipe); 1041 pipeselwakeup(wpipe); 1042 error = EPIPE; 1043 } else if (error == EINTR || error == ERESTART) { 1044 pipe_clone_write_buffer(wpipe); 1045 } else { 1046 pipe_destroy_write_buffer(wpipe); 1047 } 1048 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0, 1049 ("pipe %p leaked PIPE_DIRECTW", wpipe)); 1050 return (error); 1051 1052 error1: 1053 wakeup(wpipe); 1054 return (error); 1055 } 1056 #endif 1057 1058 static int 1059 pipe_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 1060 int flags, struct thread *td) 1061 { 1062 struct pipe *wpipe, *rpipe; 1063 ssize_t orig_resid; 1064 int desiredsize, error; 1065 1066 rpipe = fp->f_data; 1067 wpipe = PIPE_PEER(rpipe); 1068 PIPE_LOCK(rpipe); 1069 error = pipelock(wpipe, 1); 1070 if (error) { 1071 PIPE_UNLOCK(rpipe); 1072 return (error); 1073 } 1074 /* 1075 * detect loss of pipe read side, issue SIGPIPE if lost. 1076 */ 1077 if (wpipe->pipe_present != PIPE_ACTIVE || 1078 (wpipe->pipe_state & PIPE_EOF)) { 1079 pipeunlock(wpipe); 1080 PIPE_UNLOCK(rpipe); 1081 return (EPIPE); 1082 } 1083 #ifdef MAC 1084 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair); 1085 if (error) { 1086 pipeunlock(wpipe); 1087 PIPE_UNLOCK(rpipe); 1088 return (error); 1089 } 1090 #endif 1091 ++wpipe->pipe_busy; 1092 1093 /* Choose a larger size if it's advantageous */ 1094 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size); 1095 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) { 1096 if (piperesizeallowed != 1) 1097 break; 1098 if (amountpipekva > maxpipekva / 2) 1099 break; 1100 if (desiredsize == BIG_PIPE_SIZE) 1101 break; 1102 desiredsize = desiredsize * 2; 1103 } 1104 1105 /* Choose a smaller size if we're in a OOM situation */ 1106 if (amountpipekva > (3 * maxpipekva) / 4 && 1107 wpipe->pipe_buffer.size > SMALL_PIPE_SIZE && 1108 wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE && 1109 piperesizeallowed == 1) 1110 desiredsize = SMALL_PIPE_SIZE; 1111 1112 /* Resize if the above determined that a new size was necessary */ 1113 if (desiredsize != wpipe->pipe_buffer.size && 1114 (wpipe->pipe_state & PIPE_DIRECTW) == 0) { 1115 PIPE_UNLOCK(wpipe); 1116 pipespace(wpipe, desiredsize); 1117 PIPE_LOCK(wpipe); 1118 } 1119 MPASS(wpipe->pipe_buffer.size != 0); 1120 1121 orig_resid = uio->uio_resid; 1122 1123 while (uio->uio_resid) { 1124 int space; 1125 1126 if (wpipe->pipe_state & PIPE_EOF) { 1127 error = EPIPE; 1128 break; 1129 } 1130 #ifndef PIPE_NODIRECT 1131 /* 1132 * If the transfer is large, we can gain performance if 1133 * we do process-to-process copies directly. 1134 * If the write is non-blocking, we don't use the 1135 * direct write mechanism. 1136 * 1137 * The direct write mechanism will detect the reader going 1138 * away on us. 1139 */ 1140 if (uio->uio_segflg == UIO_USERSPACE && 1141 uio->uio_iov->iov_len >= PIPE_MINDIRECT && 1142 wpipe->pipe_buffer.size >= PIPE_MINDIRECT && 1143 (fp->f_flag & FNONBLOCK) == 0) { 1144 error = pipe_direct_write(wpipe, uio); 1145 if (error != 0) 1146 break; 1147 continue; 1148 } 1149 #endif 1150 1151 /* 1152 * Pipe buffered writes cannot be coincidental with 1153 * direct writes. We wait until the currently executing 1154 * direct write is completed before we start filling the 1155 * pipe buffer. We break out if a signal occurs or the 1156 * reader goes away. 1157 */ 1158 if (wpipe->pipe_pages.cnt != 0) { 1159 if (wpipe->pipe_state & PIPE_WANTR) { 1160 wpipe->pipe_state &= ~PIPE_WANTR; 1161 wakeup(wpipe); 1162 } 1163 pipeselwakeup(wpipe); 1164 wpipe->pipe_state |= PIPE_WANTW; 1165 pipeunlock(wpipe); 1166 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH, 1167 "pipbww", 0); 1168 pipelock(wpipe, 0); 1169 if (error != 0) 1170 break; 1171 continue; 1172 } 1173 1174 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1175 1176 /* Writes of size <= PIPE_BUF must be atomic. */ 1177 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 1178 space = 0; 1179 1180 if (space > 0) { 1181 int size; /* Transfer size */ 1182 int segsize; /* first segment to transfer */ 1183 1184 /* 1185 * Transfer size is minimum of uio transfer 1186 * and free space in pipe buffer. 1187 */ 1188 if (space > uio->uio_resid) 1189 size = uio->uio_resid; 1190 else 1191 size = space; 1192 /* 1193 * First segment to transfer is minimum of 1194 * transfer size and contiguous space in 1195 * pipe buffer. If first segment to transfer 1196 * is less than the transfer size, we've got 1197 * a wraparound in the buffer. 1198 */ 1199 segsize = wpipe->pipe_buffer.size - 1200 wpipe->pipe_buffer.in; 1201 if (segsize > size) 1202 segsize = size; 1203 1204 /* Transfer first segment */ 1205 1206 PIPE_UNLOCK(rpipe); 1207 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 1208 segsize, uio); 1209 PIPE_LOCK(rpipe); 1210 1211 if (error == 0 && segsize < size) { 1212 KASSERT(wpipe->pipe_buffer.in + segsize == 1213 wpipe->pipe_buffer.size, 1214 ("Pipe buffer wraparound disappeared")); 1215 /* 1216 * Transfer remaining part now, to 1217 * support atomic writes. Wraparound 1218 * happened. 1219 */ 1220 1221 PIPE_UNLOCK(rpipe); 1222 error = uiomove( 1223 &wpipe->pipe_buffer.buffer[0], 1224 size - segsize, uio); 1225 PIPE_LOCK(rpipe); 1226 } 1227 if (error == 0) { 1228 wpipe->pipe_buffer.in += size; 1229 if (wpipe->pipe_buffer.in >= 1230 wpipe->pipe_buffer.size) { 1231 KASSERT(wpipe->pipe_buffer.in == 1232 size - segsize + 1233 wpipe->pipe_buffer.size, 1234 ("Expected wraparound bad")); 1235 wpipe->pipe_buffer.in = size - segsize; 1236 } 1237 1238 wpipe->pipe_buffer.cnt += size; 1239 KASSERT(wpipe->pipe_buffer.cnt <= 1240 wpipe->pipe_buffer.size, 1241 ("Pipe buffer overflow")); 1242 } 1243 if (error != 0) 1244 break; 1245 continue; 1246 } else { 1247 /* 1248 * If the "read-side" has been blocked, wake it up now. 1249 */ 1250 if (wpipe->pipe_state & PIPE_WANTR) { 1251 wpipe->pipe_state &= ~PIPE_WANTR; 1252 wakeup(wpipe); 1253 } 1254 1255 /* 1256 * don't block on non-blocking I/O 1257 */ 1258 if (fp->f_flag & FNONBLOCK) { 1259 error = EAGAIN; 1260 break; 1261 } 1262 1263 /* 1264 * We have no more space and have something to offer, 1265 * wake up select/poll. 1266 */ 1267 pipeselwakeup(wpipe); 1268 1269 wpipe->pipe_state |= PIPE_WANTW; 1270 pipeunlock(wpipe); 1271 error = msleep(wpipe, PIPE_MTX(rpipe), 1272 PRIBIO | PCATCH, "pipewr", 0); 1273 pipelock(wpipe, 0); 1274 if (error != 0) 1275 break; 1276 continue; 1277 } 1278 } 1279 1280 --wpipe->pipe_busy; 1281 1282 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 1283 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 1284 wakeup(wpipe); 1285 } else if (wpipe->pipe_buffer.cnt > 0) { 1286 /* 1287 * If we have put any characters in the buffer, we wake up 1288 * the reader. 1289 */ 1290 if (wpipe->pipe_state & PIPE_WANTR) { 1291 wpipe->pipe_state &= ~PIPE_WANTR; 1292 wakeup(wpipe); 1293 } 1294 } 1295 1296 /* 1297 * Don't return EPIPE if any byte was written. 1298 * EINTR and other interrupts are handled by generic I/O layer. 1299 * Do not pretend that I/O succeeded for obvious user error 1300 * like EFAULT. 1301 */ 1302 if (uio->uio_resid != orig_resid && error == EPIPE) 1303 error = 0; 1304 1305 if (error == 0) 1306 pipe_timestamp(&wpipe->pipe_mtime); 1307 1308 /* 1309 * We have something to offer, 1310 * wake up select/poll. 1311 */ 1312 if (wpipe->pipe_buffer.cnt) 1313 pipeselwakeup(wpipe); 1314 1315 pipeunlock(wpipe); 1316 PIPE_UNLOCK(rpipe); 1317 return (error); 1318 } 1319 1320 /* ARGSUSED */ 1321 static int 1322 pipe_truncate(struct file *fp, off_t length, struct ucred *active_cred, 1323 struct thread *td) 1324 { 1325 struct pipe *cpipe; 1326 int error; 1327 1328 cpipe = fp->f_data; 1329 if (cpipe->pipe_type & PIPE_TYPE_NAMED) 1330 error = vnops.fo_truncate(fp, length, active_cred, td); 1331 else 1332 error = invfo_truncate(fp, length, active_cred, td); 1333 return (error); 1334 } 1335 1336 /* 1337 * we implement a very minimal set of ioctls for compatibility with sockets. 1338 */ 1339 static int 1340 pipe_ioctl(struct file *fp, u_long cmd, void *data, struct ucred *active_cred, 1341 struct thread *td) 1342 { 1343 struct pipe *mpipe = fp->f_data; 1344 int error; 1345 1346 PIPE_LOCK(mpipe); 1347 1348 #ifdef MAC 1349 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data); 1350 if (error) { 1351 PIPE_UNLOCK(mpipe); 1352 return (error); 1353 } 1354 #endif 1355 1356 error = 0; 1357 switch (cmd) { 1358 case FIONBIO: 1359 break; 1360 1361 case FIOASYNC: 1362 if (*(int *)data) { 1363 mpipe->pipe_state |= PIPE_ASYNC; 1364 } else { 1365 mpipe->pipe_state &= ~PIPE_ASYNC; 1366 } 1367 break; 1368 1369 case FIONREAD: 1370 if (!(fp->f_flag & FREAD)) { 1371 *(int *)data = 0; 1372 PIPE_UNLOCK(mpipe); 1373 return (0); 1374 } 1375 if (mpipe->pipe_pages.cnt != 0) 1376 *(int *)data = mpipe->pipe_pages.cnt; 1377 else 1378 *(int *)data = mpipe->pipe_buffer.cnt; 1379 break; 1380 1381 case FIOSETOWN: 1382 PIPE_UNLOCK(mpipe); 1383 error = fsetown(*(int *)data, &mpipe->pipe_sigio); 1384 goto out_unlocked; 1385 1386 case FIOGETOWN: 1387 *(int *)data = fgetown(&mpipe->pipe_sigio); 1388 break; 1389 1390 /* This is deprecated, FIOSETOWN should be used instead. */ 1391 case TIOCSPGRP: 1392 PIPE_UNLOCK(mpipe); 1393 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio); 1394 goto out_unlocked; 1395 1396 /* This is deprecated, FIOGETOWN should be used instead. */ 1397 case TIOCGPGRP: 1398 *(int *)data = -fgetown(&mpipe->pipe_sigio); 1399 break; 1400 1401 default: 1402 error = ENOTTY; 1403 break; 1404 } 1405 PIPE_UNLOCK(mpipe); 1406 out_unlocked: 1407 return (error); 1408 } 1409 1410 static int 1411 pipe_poll(struct file *fp, int events, struct ucred *active_cred, 1412 struct thread *td) 1413 { 1414 struct pipe *rpipe; 1415 struct pipe *wpipe; 1416 int levents, revents; 1417 #ifdef MAC 1418 int error; 1419 #endif 1420 1421 revents = 0; 1422 rpipe = fp->f_data; 1423 wpipe = PIPE_PEER(rpipe); 1424 PIPE_LOCK(rpipe); 1425 #ifdef MAC 1426 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair); 1427 if (error) 1428 goto locked_error; 1429 #endif 1430 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) 1431 if (rpipe->pipe_pages.cnt > 0 || rpipe->pipe_buffer.cnt > 0) 1432 revents |= events & (POLLIN | POLLRDNORM); 1433 1434 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) 1435 if (wpipe->pipe_present != PIPE_ACTIVE || 1436 (wpipe->pipe_state & PIPE_EOF) || 1437 ((wpipe->pipe_state & PIPE_DIRECTW) == 0 && 1438 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF || 1439 wpipe->pipe_buffer.size == 0))) 1440 revents |= events & (POLLOUT | POLLWRNORM); 1441 1442 levents = events & 1443 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND); 1444 if (rpipe->pipe_type & PIPE_TYPE_NAMED && fp->f_flag & FREAD && levents && 1445 fp->f_pipegen == rpipe->pipe_wgen) 1446 events |= POLLINIGNEOF; 1447 1448 if ((events & POLLINIGNEOF) == 0) { 1449 if (rpipe->pipe_state & PIPE_EOF) { 1450 if (fp->f_flag & FREAD) 1451 revents |= (events & (POLLIN | POLLRDNORM)); 1452 if (wpipe->pipe_present != PIPE_ACTIVE || 1453 (wpipe->pipe_state & PIPE_EOF)) 1454 revents |= POLLHUP; 1455 } 1456 } 1457 1458 if (revents == 0) { 1459 /* 1460 * Add ourselves regardless of eventmask as we have to return 1461 * POLLHUP even if it was not asked for. 1462 */ 1463 if ((fp->f_flag & FREAD) != 0) { 1464 selrecord(td, &rpipe->pipe_sel); 1465 if (SEL_WAITING(&rpipe->pipe_sel)) 1466 rpipe->pipe_state |= PIPE_SEL; 1467 } 1468 1469 if ((fp->f_flag & FWRITE) != 0) { 1470 selrecord(td, &wpipe->pipe_sel); 1471 if (SEL_WAITING(&wpipe->pipe_sel)) 1472 wpipe->pipe_state |= PIPE_SEL; 1473 } 1474 } 1475 #ifdef MAC 1476 locked_error: 1477 #endif 1478 PIPE_UNLOCK(rpipe); 1479 1480 return (revents); 1481 } 1482 1483 /* 1484 * We shouldn't need locks here as we're doing a read and this should 1485 * be a natural race. 1486 */ 1487 static int 1488 pipe_stat(struct file *fp, struct stat *ub, struct ucred *active_cred, 1489 struct thread *td) 1490 { 1491 struct pipe *pipe; 1492 #ifdef MAC 1493 int error; 1494 #endif 1495 1496 pipe = fp->f_data; 1497 #ifdef MAC 1498 if (mac_pipe_check_stat_enabled()) { 1499 PIPE_LOCK(pipe); 1500 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair); 1501 PIPE_UNLOCK(pipe); 1502 if (error) { 1503 return (error); 1504 } 1505 } 1506 #endif 1507 1508 /* For named pipes ask the underlying filesystem. */ 1509 if (pipe->pipe_type & PIPE_TYPE_NAMED) { 1510 return (vnops.fo_stat(fp, ub, active_cred, td)); 1511 } 1512 1513 bzero(ub, sizeof(*ub)); 1514 ub->st_mode = S_IFIFO; 1515 ub->st_blksize = PAGE_SIZE; 1516 if (pipe->pipe_pages.cnt != 0) 1517 ub->st_size = pipe->pipe_pages.cnt; 1518 else 1519 ub->st_size = pipe->pipe_buffer.cnt; 1520 ub->st_blocks = howmany(ub->st_size, ub->st_blksize); 1521 ub->st_atim = pipe->pipe_atime; 1522 ub->st_mtim = pipe->pipe_mtime; 1523 ub->st_ctim = pipe->pipe_ctime; 1524 ub->st_uid = fp->f_cred->cr_uid; 1525 ub->st_gid = fp->f_cred->cr_gid; 1526 ub->st_dev = pipedev_ino; 1527 ub->st_ino = pipe->pipe_ino; 1528 /* 1529 * Left as 0: st_nlink, st_rdev, st_flags, st_gen. 1530 */ 1531 return (0); 1532 } 1533 1534 /* ARGSUSED */ 1535 static int 1536 pipe_close(struct file *fp, struct thread *td) 1537 { 1538 1539 if (fp->f_vnode != NULL) 1540 return vnops.fo_close(fp, td); 1541 fp->f_ops = &badfileops; 1542 pipe_dtor(fp->f_data); 1543 fp->f_data = NULL; 1544 return (0); 1545 } 1546 1547 static int 1548 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td) 1549 { 1550 struct pipe *cpipe; 1551 int error; 1552 1553 cpipe = fp->f_data; 1554 if (cpipe->pipe_type & PIPE_TYPE_NAMED) 1555 error = vn_chmod(fp, mode, active_cred, td); 1556 else 1557 error = invfo_chmod(fp, mode, active_cred, td); 1558 return (error); 1559 } 1560 1561 static int 1562 pipe_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1563 struct thread *td) 1564 { 1565 struct pipe *cpipe; 1566 int error; 1567 1568 cpipe = fp->f_data; 1569 if (cpipe->pipe_type & PIPE_TYPE_NAMED) 1570 error = vn_chown(fp, uid, gid, active_cred, td); 1571 else 1572 error = invfo_chown(fp, uid, gid, active_cred, td); 1573 return (error); 1574 } 1575 1576 static int 1577 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp) 1578 { 1579 struct pipe *pi; 1580 1581 if (fp->f_type == DTYPE_FIFO) 1582 return (vn_fill_kinfo(fp, kif, fdp)); 1583 kif->kf_type = KF_TYPE_PIPE; 1584 pi = fp->f_data; 1585 kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi; 1586 kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer; 1587 kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt; 1588 return (0); 1589 } 1590 1591 static void 1592 pipe_free_kmem(struct pipe *cpipe) 1593 { 1594 1595 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), 1596 ("pipe_free_kmem: pipe mutex locked")); 1597 1598 if (cpipe->pipe_buffer.buffer != NULL) { 1599 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size); 1600 vm_map_remove(pipe_map, 1601 (vm_offset_t)cpipe->pipe_buffer.buffer, 1602 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size); 1603 cpipe->pipe_buffer.buffer = NULL; 1604 } 1605 #ifndef PIPE_NODIRECT 1606 { 1607 cpipe->pipe_pages.cnt = 0; 1608 cpipe->pipe_pages.pos = 0; 1609 cpipe->pipe_pages.npages = 0; 1610 } 1611 #endif 1612 } 1613 1614 /* 1615 * shutdown the pipe 1616 */ 1617 static void 1618 pipeclose(struct pipe *cpipe) 1619 { 1620 struct pipepair *pp; 1621 struct pipe *ppipe; 1622 1623 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL")); 1624 1625 PIPE_LOCK(cpipe); 1626 pipelock(cpipe, 0); 1627 pp = cpipe->pipe_pair; 1628 1629 /* 1630 * If the other side is blocked, wake it up saying that 1631 * we want to close it down. 1632 */ 1633 cpipe->pipe_state |= PIPE_EOF; 1634 while (cpipe->pipe_busy) { 1635 wakeup(cpipe); 1636 cpipe->pipe_state |= PIPE_WANT; 1637 pipeunlock(cpipe); 1638 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0); 1639 pipelock(cpipe, 0); 1640 } 1641 1642 pipeselwakeup(cpipe); 1643 1644 /* 1645 * Disconnect from peer, if any. 1646 */ 1647 ppipe = cpipe->pipe_peer; 1648 if (ppipe->pipe_present == PIPE_ACTIVE) { 1649 ppipe->pipe_state |= PIPE_EOF; 1650 wakeup(ppipe); 1651 pipeselwakeup(ppipe); 1652 } 1653 1654 /* 1655 * Mark this endpoint as free. Release kmem resources. We 1656 * don't mark this endpoint as unused until we've finished 1657 * doing that, or the pipe might disappear out from under 1658 * us. 1659 */ 1660 PIPE_UNLOCK(cpipe); 1661 pipe_free_kmem(cpipe); 1662 PIPE_LOCK(cpipe); 1663 cpipe->pipe_present = PIPE_CLOSING; 1664 pipeunlock(cpipe); 1665 1666 /* 1667 * knlist_clear() may sleep dropping the PIPE_MTX. Set the 1668 * PIPE_FINALIZED, that allows other end to free the 1669 * pipe_pair, only after the knotes are completely dismantled. 1670 */ 1671 knlist_clear(&cpipe->pipe_sel.si_note, 1); 1672 cpipe->pipe_present = PIPE_FINALIZED; 1673 seldrain(&cpipe->pipe_sel); 1674 knlist_destroy(&cpipe->pipe_sel.si_note); 1675 1676 /* 1677 * If both endpoints are now closed, release the memory for the 1678 * pipe pair. If not, unlock. 1679 */ 1680 if (ppipe->pipe_present == PIPE_FINALIZED) { 1681 PIPE_UNLOCK(cpipe); 1682 #ifdef MAC 1683 mac_pipe_destroy(pp); 1684 #endif 1685 uma_zfree(pipe_zone, cpipe->pipe_pair); 1686 } else 1687 PIPE_UNLOCK(cpipe); 1688 } 1689 1690 /*ARGSUSED*/ 1691 static int 1692 pipe_kqfilter(struct file *fp, struct knote *kn) 1693 { 1694 struct pipe *cpipe; 1695 1696 /* 1697 * If a filter is requested that is not supported by this file 1698 * descriptor, don't return an error, but also don't ever generate an 1699 * event. 1700 */ 1701 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) { 1702 kn->kn_fop = &pipe_nfiltops; 1703 return (0); 1704 } 1705 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) { 1706 kn->kn_fop = &pipe_nfiltops; 1707 return (0); 1708 } 1709 cpipe = fp->f_data; 1710 PIPE_LOCK(cpipe); 1711 switch (kn->kn_filter) { 1712 case EVFILT_READ: 1713 kn->kn_fop = &pipe_rfiltops; 1714 break; 1715 case EVFILT_WRITE: 1716 kn->kn_fop = &pipe_wfiltops; 1717 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) { 1718 /* other end of pipe has been closed */ 1719 PIPE_UNLOCK(cpipe); 1720 return (EPIPE); 1721 } 1722 cpipe = PIPE_PEER(cpipe); 1723 break; 1724 default: 1725 PIPE_UNLOCK(cpipe); 1726 return (EINVAL); 1727 } 1728 1729 kn->kn_hook = cpipe; 1730 knlist_add(&cpipe->pipe_sel.si_note, kn, 1); 1731 PIPE_UNLOCK(cpipe); 1732 return (0); 1733 } 1734 1735 static void 1736 filt_pipedetach(struct knote *kn) 1737 { 1738 struct pipe *cpipe = kn->kn_hook; 1739 1740 PIPE_LOCK(cpipe); 1741 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1); 1742 PIPE_UNLOCK(cpipe); 1743 } 1744 1745 /*ARGSUSED*/ 1746 static int 1747 filt_piperead(struct knote *kn, long hint) 1748 { 1749 struct file *fp = kn->kn_fp; 1750 struct pipe *rpipe = kn->kn_hook; 1751 1752 PIPE_LOCK_ASSERT(rpipe, MA_OWNED); 1753 kn->kn_data = rpipe->pipe_buffer.cnt; 1754 if (kn->kn_data == 0) 1755 kn->kn_data = rpipe->pipe_pages.cnt; 1756 1757 if ((rpipe->pipe_state & PIPE_EOF) != 0 && 1758 ((rpipe->pipe_type & PIPE_TYPE_NAMED) == 0 || 1759 fp->f_pipegen != rpipe->pipe_wgen)) { 1760 kn->kn_flags |= EV_EOF; 1761 return (1); 1762 } 1763 kn->kn_flags &= ~EV_EOF; 1764 return (kn->kn_data > 0); 1765 } 1766 1767 /*ARGSUSED*/ 1768 static int 1769 filt_pipewrite(struct knote *kn, long hint) 1770 { 1771 struct pipe *wpipe = kn->kn_hook; 1772 1773 /* 1774 * If this end of the pipe is closed, the knote was removed from the 1775 * knlist and the list lock (i.e., the pipe lock) is therefore not held. 1776 */ 1777 if (wpipe->pipe_present == PIPE_ACTIVE || 1778 (wpipe->pipe_type & PIPE_TYPE_NAMED) != 0) { 1779 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 1780 1781 if (wpipe->pipe_state & PIPE_DIRECTW) { 1782 kn->kn_data = 0; 1783 } else if (wpipe->pipe_buffer.size > 0) { 1784 kn->kn_data = wpipe->pipe_buffer.size - 1785 wpipe->pipe_buffer.cnt; 1786 } else { 1787 kn->kn_data = PIPE_BUF; 1788 } 1789 } 1790 1791 if (wpipe->pipe_present != PIPE_ACTIVE || 1792 (wpipe->pipe_state & PIPE_EOF)) { 1793 kn->kn_flags |= EV_EOF; 1794 return (1); 1795 } 1796 kn->kn_flags &= ~EV_EOF; 1797 return (kn->kn_data >= PIPE_BUF); 1798 } 1799 1800 static void 1801 filt_pipedetach_notsup(struct knote *kn) 1802 { 1803 1804 } 1805 1806 static int 1807 filt_pipenotsup(struct knote *kn, long hint) 1808 { 1809 1810 return (0); 1811 } 1812