1 /*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 4 * Copyright (c) 1996 John S. Dyson 5 * Copyright (c) 2012 Giovanni Trematerra 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice immediately at the beginning of the file, without modification, 13 * this list of conditions, and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Absolutely no warranty of function or purpose is made by the author 18 * John S. Dyson. 19 * 4. Modifications may be freely made to this file if the above conditions 20 * are met. 21 */ 22 23 /* 24 * This file contains a high-performance replacement for the socket-based 25 * pipes scheme originally used in FreeBSD/4.4Lite. It does not support 26 * all features of sockets, but does do everything that pipes normally 27 * do. 28 */ 29 30 /* 31 * This code has two modes of operation, a small write mode and a large 32 * write mode. The small write mode acts like conventional pipes with 33 * a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the 34 * "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT 35 * and PIPE_SIZE in size, the sending process pins the underlying pages in 36 * memory, and the receiving process copies directly from these pinned pages 37 * in the sending process. 38 * 39 * If the sending process receives a signal, it is possible that it will 40 * go away, and certainly its address space can change, because control 41 * is returned back to the user-mode side. In that case, the pipe code 42 * arranges to copy the buffer supplied by the user process, to a pageable 43 * kernel buffer, and the receiving process will grab the data from the 44 * pageable kernel buffer. Since signals don't happen all that often, 45 * the copy operation is normally eliminated. 46 * 47 * The constant PIPE_MINDIRECT is chosen to make sure that buffering will 48 * happen for small transfers so that the system will not spend all of 49 * its time context switching. 50 * 51 * In order to limit the resource use of pipes, two sysctls exist: 52 * 53 * kern.ipc.maxpipekva - This is a hard limit on the amount of pageable 54 * address space available to us in pipe_map. This value is normally 55 * autotuned, but may also be loader tuned. 56 * 57 * kern.ipc.pipekva - This read-only sysctl tracks the current amount of 58 * memory in use by pipes. 59 * 60 * Based on how large pipekva is relative to maxpipekva, the following 61 * will happen: 62 * 63 * 0% - 50%: 64 * New pipes are given 16K of memory backing, pipes may dynamically 65 * grow to as large as 64K where needed. 66 * 50% - 75%: 67 * New pipes are given 4K (or PAGE_SIZE) of memory backing, 68 * existing pipes may NOT grow. 69 * 75% - 100%: 70 * New pipes are given 4K (or PAGE_SIZE) of memory backing, 71 * existing pipes will be shrunk down to 4K whenever possible. 72 * 73 * Resizing may be disabled by setting kern.ipc.piperesizeallowed=0. If 74 * that is set, the only resize that will occur is the 0 -> SMALL_PIPE_SIZE 75 * resize which MUST occur for reverse-direction pipes when they are 76 * first used. 77 * 78 * Additional information about the current state of pipes may be obtained 79 * from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail, 80 * and kern.ipc.piperesizefail. 81 * 82 * Locking rules: There are two locks present here: A mutex, used via 83 * PIPE_LOCK, and a flag, used via pipelock(). All locking is done via 84 * the flag, as mutexes can not persist over uiomove. The mutex 85 * exists only to guard access to the flag, and is not in itself a 86 * locking mechanism. Also note that there is only a single mutex for 87 * both directions of a pipe. 88 * 89 * As pipelock() may have to sleep before it can acquire the flag, it 90 * is important to reread all data after a call to pipelock(); everything 91 * in the structure may have changed. 92 */ 93 94 #include <sys/cdefs.h> 95 __FBSDID("$FreeBSD$"); 96 97 #include <sys/param.h> 98 #include <sys/systm.h> 99 #include <sys/conf.h> 100 #include <sys/fcntl.h> 101 #include <sys/file.h> 102 #include <sys/filedesc.h> 103 #include <sys/filio.h> 104 #include <sys/kernel.h> 105 #include <sys/lock.h> 106 #include <sys/mutex.h> 107 #include <sys/ttycom.h> 108 #include <sys/stat.h> 109 #include <sys/malloc.h> 110 #include <sys/poll.h> 111 #include <sys/selinfo.h> 112 #include <sys/signalvar.h> 113 #include <sys/syscallsubr.h> 114 #include <sys/sysctl.h> 115 #include <sys/sysproto.h> 116 #include <sys/pipe.h> 117 #include <sys/proc.h> 118 #include <sys/vnode.h> 119 #include <sys/uio.h> 120 #include <sys/user.h> 121 #include <sys/event.h> 122 123 #include <security/mac/mac_framework.h> 124 125 #include <vm/vm.h> 126 #include <vm/vm_param.h> 127 #include <vm/vm_object.h> 128 #include <vm/vm_kern.h> 129 #include <vm/vm_extern.h> 130 #include <vm/pmap.h> 131 #include <vm/vm_map.h> 132 #include <vm/vm_page.h> 133 #include <vm/uma.h> 134 135 /* 136 * Use this define if you want to disable *fancy* VM things. Expect an 137 * approx 30% decrease in transfer rate. This could be useful for 138 * NetBSD or OpenBSD. 139 */ 140 /* #define PIPE_NODIRECT */ 141 142 #define PIPE_PEER(pipe) \ 143 (((pipe)->pipe_state & PIPE_NAMED) ? (pipe) : ((pipe)->pipe_peer)) 144 145 /* 146 * interfaces to the outside world 147 */ 148 static fo_rdwr_t pipe_read; 149 static fo_rdwr_t pipe_write; 150 static fo_truncate_t pipe_truncate; 151 static fo_ioctl_t pipe_ioctl; 152 static fo_poll_t pipe_poll; 153 static fo_kqfilter_t pipe_kqfilter; 154 static fo_stat_t pipe_stat; 155 static fo_close_t pipe_close; 156 static fo_chmod_t pipe_chmod; 157 static fo_chown_t pipe_chown; 158 static fo_fill_kinfo_t pipe_fill_kinfo; 159 160 struct fileops pipeops = { 161 .fo_read = pipe_read, 162 .fo_write = pipe_write, 163 .fo_truncate = pipe_truncate, 164 .fo_ioctl = pipe_ioctl, 165 .fo_poll = pipe_poll, 166 .fo_kqfilter = pipe_kqfilter, 167 .fo_stat = pipe_stat, 168 .fo_close = pipe_close, 169 .fo_chmod = pipe_chmod, 170 .fo_chown = pipe_chown, 171 .fo_sendfile = invfo_sendfile, 172 .fo_fill_kinfo = pipe_fill_kinfo, 173 .fo_flags = DFLAG_PASSABLE 174 }; 175 176 static void filt_pipedetach(struct knote *kn); 177 static void filt_pipedetach_notsup(struct knote *kn); 178 static int filt_pipenotsup(struct knote *kn, long hint); 179 static int filt_piperead(struct knote *kn, long hint); 180 static int filt_pipewrite(struct knote *kn, long hint); 181 182 static struct filterops pipe_nfiltops = { 183 .f_isfd = 1, 184 .f_detach = filt_pipedetach_notsup, 185 .f_event = filt_pipenotsup 186 }; 187 static struct filterops pipe_rfiltops = { 188 .f_isfd = 1, 189 .f_detach = filt_pipedetach, 190 .f_event = filt_piperead 191 }; 192 static struct filterops pipe_wfiltops = { 193 .f_isfd = 1, 194 .f_detach = filt_pipedetach, 195 .f_event = filt_pipewrite 196 }; 197 198 /* 199 * Default pipe buffer size(s), this can be kind-of large now because pipe 200 * space is pageable. The pipe code will try to maintain locality of 201 * reference for performance reasons, so small amounts of outstanding I/O 202 * will not wipe the cache. 203 */ 204 #define MINPIPESIZE (PIPE_SIZE/3) 205 #define MAXPIPESIZE (2*PIPE_SIZE/3) 206 207 static long amountpipekva; 208 static int pipefragretry; 209 static int pipeallocfail; 210 static int piperesizefail; 211 static int piperesizeallowed = 1; 212 213 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, 214 &maxpipekva, 0, "Pipe KVA limit"); 215 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD, 216 &amountpipekva, 0, "Pipe KVA usage"); 217 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD, 218 &pipefragretry, 0, "Pipe allocation retries due to fragmentation"); 219 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD, 220 &pipeallocfail, 0, "Pipe allocation failures"); 221 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD, 222 &piperesizefail, 0, "Pipe resize failures"); 223 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW, 224 &piperesizeallowed, 0, "Pipe resizing allowed"); 225 226 static void pipeinit(void *dummy __unused); 227 static void pipeclose(struct pipe *cpipe); 228 static void pipe_free_kmem(struct pipe *cpipe); 229 static 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_state |= PIPE_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_state & PIPE_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; 618 619 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 620 while (cpipe->pipe_state & PIPE_LOCKFL) { 621 cpipe->pipe_state |= PIPE_LWANT; 622 error = msleep(cpipe, PIPE_MTX(cpipe), 623 catch ? (PRIBIO | PCATCH) : PRIBIO, 624 "pipelk", 0); 625 if (error != 0) 626 return (error); 627 } 628 cpipe->pipe_state |= PIPE_LOCKFL; 629 return (0); 630 } 631 632 /* 633 * unlock a pipe I/O lock 634 */ 635 static __inline void 636 pipeunlock(struct pipe *cpipe) 637 { 638 639 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 640 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 641 ("Unlocked pipe passed to pipeunlock")); 642 cpipe->pipe_state &= ~PIPE_LOCKFL; 643 if (cpipe->pipe_state & PIPE_LWANT) { 644 cpipe->pipe_state &= ~PIPE_LWANT; 645 wakeup(cpipe); 646 } 647 } 648 649 void 650 pipeselwakeup(struct pipe *cpipe) 651 { 652 653 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 654 if (cpipe->pipe_state & PIPE_SEL) { 655 selwakeuppri(&cpipe->pipe_sel, PSOCK); 656 if (!SEL_WAITING(&cpipe->pipe_sel)) 657 cpipe->pipe_state &= ~PIPE_SEL; 658 } 659 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) 660 pgsigio(&cpipe->pipe_sigio, SIGIO, 0); 661 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0); 662 } 663 664 /* 665 * Initialize and allocate VM and memory for pipe. The structure 666 * will start out zero'd from the ctor, so we just manage the kmem. 667 */ 668 static int 669 pipe_create(struct pipe *pipe, bool large_backing) 670 { 671 int error; 672 673 error = pipespace_new(pipe, !large_backing || amountpipekva > 674 maxpipekva / 2 ? SMALL_PIPE_SIZE : PIPE_SIZE); 675 if (error == 0) 676 pipe->pipe_ino = alloc_unr64(&pipeino_unr); 677 return (error); 678 } 679 680 /* ARGSUSED */ 681 static int 682 pipe_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 683 int flags, struct thread *td) 684 { 685 struct pipe *rpipe; 686 int error; 687 int nread = 0; 688 int size; 689 690 rpipe = fp->f_data; 691 PIPE_LOCK(rpipe); 692 ++rpipe->pipe_busy; 693 error = pipelock(rpipe, 1); 694 if (error) 695 goto unlocked_error; 696 697 #ifdef MAC 698 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair); 699 if (error) 700 goto locked_error; 701 #endif 702 if (amountpipekva > (3 * maxpipekva) / 4) { 703 if ((rpipe->pipe_state & PIPE_DIRECTW) == 0 && 704 rpipe->pipe_buffer.size > SMALL_PIPE_SIZE && 705 rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE && 706 piperesizeallowed == 1) { 707 PIPE_UNLOCK(rpipe); 708 pipespace(rpipe, SMALL_PIPE_SIZE); 709 PIPE_LOCK(rpipe); 710 } 711 } 712 713 while (uio->uio_resid) { 714 /* 715 * normal pipe buffer receive 716 */ 717 if (rpipe->pipe_buffer.cnt > 0) { 718 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 719 if (size > rpipe->pipe_buffer.cnt) 720 size = rpipe->pipe_buffer.cnt; 721 if (size > uio->uio_resid) 722 size = uio->uio_resid; 723 724 PIPE_UNLOCK(rpipe); 725 error = uiomove( 726 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 727 size, uio); 728 PIPE_LOCK(rpipe); 729 if (error) 730 break; 731 732 rpipe->pipe_buffer.out += size; 733 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 734 rpipe->pipe_buffer.out = 0; 735 736 rpipe->pipe_buffer.cnt -= size; 737 738 /* 739 * If there is no more to read in the pipe, reset 740 * its pointers to the beginning. This improves 741 * cache hit stats. 742 */ 743 if (rpipe->pipe_buffer.cnt == 0) { 744 rpipe->pipe_buffer.in = 0; 745 rpipe->pipe_buffer.out = 0; 746 } 747 nread += size; 748 #ifndef PIPE_NODIRECT 749 /* 750 * Direct copy, bypassing a kernel buffer. 751 */ 752 } else if ((size = rpipe->pipe_pages.cnt) != 0) { 753 if (size > uio->uio_resid) 754 size = (u_int) uio->uio_resid; 755 PIPE_UNLOCK(rpipe); 756 error = uiomove_fromphys(rpipe->pipe_pages.ms, 757 rpipe->pipe_pages.pos, size, uio); 758 PIPE_LOCK(rpipe); 759 if (error) 760 break; 761 nread += size; 762 rpipe->pipe_pages.pos += size; 763 rpipe->pipe_pages.cnt -= size; 764 if (rpipe->pipe_pages.cnt == 0) { 765 rpipe->pipe_state &= ~PIPE_WANTW; 766 wakeup(rpipe); 767 } 768 #endif 769 } else { 770 /* 771 * detect EOF condition 772 * read returns 0 on EOF, no need to set error 773 */ 774 if (rpipe->pipe_state & PIPE_EOF) 775 break; 776 777 /* 778 * If the "write-side" has been blocked, wake it up now. 779 */ 780 if (rpipe->pipe_state & PIPE_WANTW) { 781 rpipe->pipe_state &= ~PIPE_WANTW; 782 wakeup(rpipe); 783 } 784 785 /* 786 * Break if some data was read. 787 */ 788 if (nread > 0) 789 break; 790 791 /* 792 * Unlock the pipe buffer for our remaining processing. 793 * We will either break out with an error or we will 794 * sleep and relock to loop. 795 */ 796 pipeunlock(rpipe); 797 798 /* 799 * Handle non-blocking mode operation or 800 * wait for more data. 801 */ 802 if (fp->f_flag & FNONBLOCK) { 803 error = EAGAIN; 804 } else { 805 rpipe->pipe_state |= PIPE_WANTR; 806 if ((error = msleep(rpipe, PIPE_MTX(rpipe), 807 PRIBIO | PCATCH, 808 "piperd", 0)) == 0) 809 error = pipelock(rpipe, 1); 810 } 811 if (error) 812 goto unlocked_error; 813 } 814 } 815 #ifdef MAC 816 locked_error: 817 #endif 818 pipeunlock(rpipe); 819 820 /* XXX: should probably do this before getting any locks. */ 821 if (error == 0) 822 pipe_timestamp(&rpipe->pipe_atime); 823 unlocked_error: 824 --rpipe->pipe_busy; 825 826 /* 827 * PIPE_WANT processing only makes sense if pipe_busy is 0. 828 */ 829 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 830 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 831 wakeup(rpipe); 832 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 833 /* 834 * Handle write blocking hysteresis. 835 */ 836 if (rpipe->pipe_state & PIPE_WANTW) { 837 rpipe->pipe_state &= ~PIPE_WANTW; 838 wakeup(rpipe); 839 } 840 } 841 842 /* 843 * Only wake up writers if there was actually something read. 844 * Otherwise, when calling read(2) at EOF, a spurious wakeup occurs. 845 */ 846 if (nread > 0 && 847 rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt >= PIPE_BUF) 848 pipeselwakeup(rpipe); 849 850 PIPE_UNLOCK(rpipe); 851 return (error); 852 } 853 854 #ifndef PIPE_NODIRECT 855 /* 856 * Map the sending processes' buffer into kernel space and wire it. 857 * This is similar to a physical write operation. 858 */ 859 static int 860 pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio) 861 { 862 u_int size; 863 int i; 864 865 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 866 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0, 867 ("%s: PIPE_DIRECTW set on %p", __func__, wpipe)); 868 KASSERT(wpipe->pipe_pages.cnt == 0, 869 ("%s: pipe map for %p contains residual data", __func__, wpipe)); 870 871 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size) 872 size = wpipe->pipe_buffer.size; 873 else 874 size = uio->uio_iov->iov_len; 875 876 wpipe->pipe_state |= PIPE_DIRECTW; 877 PIPE_UNLOCK(wpipe); 878 i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 879 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ, 880 wpipe->pipe_pages.ms, PIPENPAGES); 881 PIPE_LOCK(wpipe); 882 if (i < 0) { 883 wpipe->pipe_state &= ~PIPE_DIRECTW; 884 return (EFAULT); 885 } 886 887 wpipe->pipe_pages.npages = i; 888 wpipe->pipe_pages.pos = 889 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 890 wpipe->pipe_pages.cnt = size; 891 892 uio->uio_iov->iov_len -= size; 893 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size; 894 if (uio->uio_iov->iov_len == 0) 895 uio->uio_iov++; 896 uio->uio_resid -= size; 897 uio->uio_offset += size; 898 return (0); 899 } 900 901 /* 902 * Unwire the process buffer. 903 */ 904 static void 905 pipe_destroy_write_buffer(struct pipe *wpipe) 906 { 907 908 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 909 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0, 910 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe)); 911 KASSERT(wpipe->pipe_pages.cnt == 0, 912 ("%s: pipe map for %p contains residual data", __func__, wpipe)); 913 914 wpipe->pipe_state &= ~PIPE_DIRECTW; 915 vm_page_unhold_pages(wpipe->pipe_pages.ms, wpipe->pipe_pages.npages); 916 wpipe->pipe_pages.npages = 0; 917 } 918 919 /* 920 * In the case of a signal, the writing process might go away. This 921 * code copies the data into the circular buffer so that the source 922 * pages can be freed without loss of data. 923 */ 924 static void 925 pipe_clone_write_buffer(struct pipe *wpipe) 926 { 927 struct uio uio; 928 struct iovec iov; 929 int size; 930 int pos; 931 932 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 933 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0, 934 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe)); 935 936 size = wpipe->pipe_pages.cnt; 937 pos = wpipe->pipe_pages.pos; 938 wpipe->pipe_pages.cnt = 0; 939 940 wpipe->pipe_buffer.in = size; 941 wpipe->pipe_buffer.out = 0; 942 wpipe->pipe_buffer.cnt = size; 943 944 PIPE_UNLOCK(wpipe); 945 iov.iov_base = wpipe->pipe_buffer.buffer; 946 iov.iov_len = size; 947 uio.uio_iov = &iov; 948 uio.uio_iovcnt = 1; 949 uio.uio_offset = 0; 950 uio.uio_resid = size; 951 uio.uio_segflg = UIO_SYSSPACE; 952 uio.uio_rw = UIO_READ; 953 uio.uio_td = curthread; 954 uiomove_fromphys(wpipe->pipe_pages.ms, pos, size, &uio); 955 PIPE_LOCK(wpipe); 956 pipe_destroy_write_buffer(wpipe); 957 } 958 959 /* 960 * This implements the pipe buffer write mechanism. Note that only 961 * a direct write OR a normal pipe write can be pending at any given time. 962 * If there are any characters in the pipe buffer, the direct write will 963 * be deferred until the receiving process grabs all of the bytes from 964 * the pipe buffer. Then the direct mapping write is set-up. 965 */ 966 static int 967 pipe_direct_write(struct pipe *wpipe, struct uio *uio) 968 { 969 int error; 970 971 retry: 972 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 973 error = pipelock(wpipe, 1); 974 if (error != 0) 975 goto error1; 976 if ((wpipe->pipe_state & PIPE_EOF) != 0) { 977 error = EPIPE; 978 pipeunlock(wpipe); 979 goto error1; 980 } 981 if (wpipe->pipe_state & PIPE_DIRECTW) { 982 if (wpipe->pipe_state & PIPE_WANTR) { 983 wpipe->pipe_state &= ~PIPE_WANTR; 984 wakeup(wpipe); 985 } 986 pipeselwakeup(wpipe); 987 wpipe->pipe_state |= PIPE_WANTW; 988 pipeunlock(wpipe); 989 error = msleep(wpipe, PIPE_MTX(wpipe), 990 PRIBIO | PCATCH, "pipdww", 0); 991 if (error) 992 goto error1; 993 else 994 goto retry; 995 } 996 if (wpipe->pipe_buffer.cnt > 0) { 997 if (wpipe->pipe_state & PIPE_WANTR) { 998 wpipe->pipe_state &= ~PIPE_WANTR; 999 wakeup(wpipe); 1000 } 1001 pipeselwakeup(wpipe); 1002 wpipe->pipe_state |= PIPE_WANTW; 1003 pipeunlock(wpipe); 1004 error = msleep(wpipe, PIPE_MTX(wpipe), 1005 PRIBIO | PCATCH, "pipdwc", 0); 1006 if (error) 1007 goto error1; 1008 else 1009 goto retry; 1010 } 1011 1012 error = pipe_build_write_buffer(wpipe, uio); 1013 if (error) { 1014 pipeunlock(wpipe); 1015 goto error1; 1016 } 1017 1018 while (wpipe->pipe_pages.cnt != 0 && 1019 (wpipe->pipe_state & PIPE_EOF) == 0) { 1020 if (wpipe->pipe_state & PIPE_WANTR) { 1021 wpipe->pipe_state &= ~PIPE_WANTR; 1022 wakeup(wpipe); 1023 } 1024 pipeselwakeup(wpipe); 1025 wpipe->pipe_state |= PIPE_WANTW; 1026 pipeunlock(wpipe); 1027 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH, 1028 "pipdwt", 0); 1029 pipelock(wpipe, 0); 1030 if (error != 0) 1031 break; 1032 } 1033 1034 if ((wpipe->pipe_state & PIPE_EOF) != 0) { 1035 wpipe->pipe_pages.cnt = 0; 1036 pipe_destroy_write_buffer(wpipe); 1037 pipeselwakeup(wpipe); 1038 error = EPIPE; 1039 } else if (error == EINTR || error == ERESTART) { 1040 pipe_clone_write_buffer(wpipe); 1041 } else { 1042 pipe_destroy_write_buffer(wpipe); 1043 } 1044 pipeunlock(wpipe); 1045 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0, 1046 ("pipe %p leaked PIPE_DIRECTW", wpipe)); 1047 return (error); 1048 1049 error1: 1050 wakeup(wpipe); 1051 return (error); 1052 } 1053 #endif 1054 1055 static int 1056 pipe_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 1057 int flags, struct thread *td) 1058 { 1059 struct pipe *wpipe, *rpipe; 1060 ssize_t orig_resid; 1061 int desiredsize, error; 1062 1063 rpipe = fp->f_data; 1064 wpipe = PIPE_PEER(rpipe); 1065 PIPE_LOCK(rpipe); 1066 error = pipelock(wpipe, 1); 1067 if (error) { 1068 PIPE_UNLOCK(rpipe); 1069 return (error); 1070 } 1071 /* 1072 * detect loss of pipe read side, issue SIGPIPE if lost. 1073 */ 1074 if (wpipe->pipe_present != PIPE_ACTIVE || 1075 (wpipe->pipe_state & PIPE_EOF)) { 1076 pipeunlock(wpipe); 1077 PIPE_UNLOCK(rpipe); 1078 return (EPIPE); 1079 } 1080 #ifdef MAC 1081 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair); 1082 if (error) { 1083 pipeunlock(wpipe); 1084 PIPE_UNLOCK(rpipe); 1085 return (error); 1086 } 1087 #endif 1088 ++wpipe->pipe_busy; 1089 1090 /* Choose a larger size if it's advantageous */ 1091 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size); 1092 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) { 1093 if (piperesizeallowed != 1) 1094 break; 1095 if (amountpipekva > maxpipekva / 2) 1096 break; 1097 if (desiredsize == BIG_PIPE_SIZE) 1098 break; 1099 desiredsize = desiredsize * 2; 1100 } 1101 1102 /* Choose a smaller size if we're in a OOM situation */ 1103 if (amountpipekva > (3 * maxpipekva) / 4 && 1104 wpipe->pipe_buffer.size > SMALL_PIPE_SIZE && 1105 wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE && 1106 piperesizeallowed == 1) 1107 desiredsize = SMALL_PIPE_SIZE; 1108 1109 /* Resize if the above determined that a new size was necessary */ 1110 if (desiredsize != wpipe->pipe_buffer.size && 1111 (wpipe->pipe_state & PIPE_DIRECTW) == 0) { 1112 PIPE_UNLOCK(wpipe); 1113 pipespace(wpipe, desiredsize); 1114 PIPE_LOCK(wpipe); 1115 } 1116 MPASS(wpipe->pipe_buffer.size != 0); 1117 1118 pipeunlock(wpipe); 1119 1120 orig_resid = uio->uio_resid; 1121 1122 while (uio->uio_resid) { 1123 int space; 1124 1125 pipelock(wpipe, 0); 1126 if (wpipe->pipe_state & PIPE_EOF) { 1127 pipeunlock(wpipe); 1128 error = EPIPE; 1129 break; 1130 } 1131 #ifndef PIPE_NODIRECT 1132 /* 1133 * If the transfer is large, we can gain performance if 1134 * we do process-to-process copies directly. 1135 * If the write is non-blocking, we don't use the 1136 * direct write mechanism. 1137 * 1138 * The direct write mechanism will detect the reader going 1139 * away on us. 1140 */ 1141 if (uio->uio_segflg == UIO_USERSPACE && 1142 uio->uio_iov->iov_len >= PIPE_MINDIRECT && 1143 wpipe->pipe_buffer.size >= PIPE_MINDIRECT && 1144 (fp->f_flag & FNONBLOCK) == 0) { 1145 pipeunlock(wpipe); 1146 error = pipe_direct_write(wpipe, uio); 1147 if (error) 1148 break; 1149 continue; 1150 } 1151 #endif 1152 1153 /* 1154 * Pipe buffered writes cannot be coincidental with 1155 * direct writes. We wait until the currently executing 1156 * direct write is completed before we start filling the 1157 * pipe buffer. We break out if a signal occurs or the 1158 * reader goes away. 1159 */ 1160 if (wpipe->pipe_pages.cnt != 0) { 1161 if (wpipe->pipe_state & PIPE_WANTR) { 1162 wpipe->pipe_state &= ~PIPE_WANTR; 1163 wakeup(wpipe); 1164 } 1165 pipeselwakeup(wpipe); 1166 wpipe->pipe_state |= PIPE_WANTW; 1167 pipeunlock(wpipe); 1168 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH, 1169 "pipbww", 0); 1170 if (error) 1171 break; 1172 else 1173 continue; 1174 } 1175 1176 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1177 1178 /* Writes of size <= PIPE_BUF must be atomic. */ 1179 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 1180 space = 0; 1181 1182 if (space > 0) { 1183 int size; /* Transfer size */ 1184 int segsize; /* first segment to transfer */ 1185 1186 /* 1187 * Transfer size is minimum of uio transfer 1188 * and free space in pipe buffer. 1189 */ 1190 if (space > uio->uio_resid) 1191 size = uio->uio_resid; 1192 else 1193 size = space; 1194 /* 1195 * First segment to transfer is minimum of 1196 * transfer size and contiguous space in 1197 * pipe buffer. If first segment to transfer 1198 * is less than the transfer size, we've got 1199 * a wraparound in the buffer. 1200 */ 1201 segsize = wpipe->pipe_buffer.size - 1202 wpipe->pipe_buffer.in; 1203 if (segsize > size) 1204 segsize = size; 1205 1206 /* Transfer first segment */ 1207 1208 PIPE_UNLOCK(rpipe); 1209 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 1210 segsize, uio); 1211 PIPE_LOCK(rpipe); 1212 1213 if (error == 0 && segsize < size) { 1214 KASSERT(wpipe->pipe_buffer.in + segsize == 1215 wpipe->pipe_buffer.size, 1216 ("Pipe buffer wraparound disappeared")); 1217 /* 1218 * Transfer remaining part now, to 1219 * support atomic writes. Wraparound 1220 * happened. 1221 */ 1222 1223 PIPE_UNLOCK(rpipe); 1224 error = uiomove( 1225 &wpipe->pipe_buffer.buffer[0], 1226 size - segsize, uio); 1227 PIPE_LOCK(rpipe); 1228 } 1229 if (error == 0) { 1230 wpipe->pipe_buffer.in += size; 1231 if (wpipe->pipe_buffer.in >= 1232 wpipe->pipe_buffer.size) { 1233 KASSERT(wpipe->pipe_buffer.in == 1234 size - segsize + 1235 wpipe->pipe_buffer.size, 1236 ("Expected wraparound bad")); 1237 wpipe->pipe_buffer.in = size - segsize; 1238 } 1239 1240 wpipe->pipe_buffer.cnt += size; 1241 KASSERT(wpipe->pipe_buffer.cnt <= 1242 wpipe->pipe_buffer.size, 1243 ("Pipe buffer overflow")); 1244 } 1245 pipeunlock(wpipe); 1246 if (error != 0) 1247 break; 1248 } else { 1249 /* 1250 * If the "read-side" has been blocked, wake it up now. 1251 */ 1252 if (wpipe->pipe_state & PIPE_WANTR) { 1253 wpipe->pipe_state &= ~PIPE_WANTR; 1254 wakeup(wpipe); 1255 } 1256 1257 /* 1258 * don't block on non-blocking I/O 1259 */ 1260 if (fp->f_flag & FNONBLOCK) { 1261 error = EAGAIN; 1262 pipeunlock(wpipe); 1263 break; 1264 } 1265 1266 /* 1267 * We have no more space and have something to offer, 1268 * wake up select/poll. 1269 */ 1270 pipeselwakeup(wpipe); 1271 1272 wpipe->pipe_state |= PIPE_WANTW; 1273 pipeunlock(wpipe); 1274 error = msleep(wpipe, PIPE_MTX(rpipe), 1275 PRIBIO | PCATCH, "pipewr", 0); 1276 if (error != 0) 1277 break; 1278 } 1279 } 1280 1281 pipelock(wpipe, 0); 1282 --wpipe->pipe_busy; 1283 1284 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 1285 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 1286 wakeup(wpipe); 1287 } else if (wpipe->pipe_buffer.cnt > 0) { 1288 /* 1289 * If we have put any characters in the buffer, we wake up 1290 * the reader. 1291 */ 1292 if (wpipe->pipe_state & PIPE_WANTR) { 1293 wpipe->pipe_state &= ~PIPE_WANTR; 1294 wakeup(wpipe); 1295 } 1296 } 1297 1298 /* 1299 * Don't return EPIPE if any byte was written. 1300 * EINTR and other interrupts are handled by generic I/O layer. 1301 * Do not pretend that I/O succeeded for obvious user error 1302 * like EFAULT. 1303 */ 1304 if (uio->uio_resid != orig_resid && error == EPIPE) 1305 error = 0; 1306 1307 if (error == 0) 1308 pipe_timestamp(&wpipe->pipe_mtime); 1309 1310 /* 1311 * We have something to offer, 1312 * wake up select/poll. 1313 */ 1314 if (wpipe->pipe_buffer.cnt) 1315 pipeselwakeup(wpipe); 1316 1317 pipeunlock(wpipe); 1318 PIPE_UNLOCK(rpipe); 1319 return (error); 1320 } 1321 1322 /* ARGSUSED */ 1323 static int 1324 pipe_truncate(struct file *fp, off_t length, struct ucred *active_cred, 1325 struct thread *td) 1326 { 1327 struct pipe *cpipe; 1328 int error; 1329 1330 cpipe = fp->f_data; 1331 if (cpipe->pipe_state & PIPE_NAMED) 1332 error = vnops.fo_truncate(fp, length, active_cred, td); 1333 else 1334 error = invfo_truncate(fp, length, active_cred, td); 1335 return (error); 1336 } 1337 1338 /* 1339 * we implement a very minimal set of ioctls for compatibility with sockets. 1340 */ 1341 static int 1342 pipe_ioctl(struct file *fp, u_long cmd, void *data, struct ucred *active_cred, 1343 struct thread *td) 1344 { 1345 struct pipe *mpipe = fp->f_data; 1346 int error; 1347 1348 PIPE_LOCK(mpipe); 1349 1350 #ifdef MAC 1351 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data); 1352 if (error) { 1353 PIPE_UNLOCK(mpipe); 1354 return (error); 1355 } 1356 #endif 1357 1358 error = 0; 1359 switch (cmd) { 1360 case FIONBIO: 1361 break; 1362 1363 case FIOASYNC: 1364 if (*(int *)data) { 1365 mpipe->pipe_state |= PIPE_ASYNC; 1366 } else { 1367 mpipe->pipe_state &= ~PIPE_ASYNC; 1368 } 1369 break; 1370 1371 case FIONREAD: 1372 if (!(fp->f_flag & FREAD)) { 1373 *(int *)data = 0; 1374 PIPE_UNLOCK(mpipe); 1375 return (0); 1376 } 1377 if (mpipe->pipe_pages.cnt != 0) 1378 *(int *)data = mpipe->pipe_pages.cnt; 1379 else 1380 *(int *)data = mpipe->pipe_buffer.cnt; 1381 break; 1382 1383 case FIOSETOWN: 1384 PIPE_UNLOCK(mpipe); 1385 error = fsetown(*(int *)data, &mpipe->pipe_sigio); 1386 goto out_unlocked; 1387 1388 case FIOGETOWN: 1389 *(int *)data = fgetown(&mpipe->pipe_sigio); 1390 break; 1391 1392 /* This is deprecated, FIOSETOWN should be used instead. */ 1393 case TIOCSPGRP: 1394 PIPE_UNLOCK(mpipe); 1395 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio); 1396 goto out_unlocked; 1397 1398 /* This is deprecated, FIOGETOWN should be used instead. */ 1399 case TIOCGPGRP: 1400 *(int *)data = -fgetown(&mpipe->pipe_sigio); 1401 break; 1402 1403 default: 1404 error = ENOTTY; 1405 break; 1406 } 1407 PIPE_UNLOCK(mpipe); 1408 out_unlocked: 1409 return (error); 1410 } 1411 1412 static int 1413 pipe_poll(struct file *fp, int events, struct ucred *active_cred, 1414 struct thread *td) 1415 { 1416 struct pipe *rpipe; 1417 struct pipe *wpipe; 1418 int levents, revents; 1419 #ifdef MAC 1420 int error; 1421 #endif 1422 1423 revents = 0; 1424 rpipe = fp->f_data; 1425 wpipe = PIPE_PEER(rpipe); 1426 PIPE_LOCK(rpipe); 1427 #ifdef MAC 1428 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair); 1429 if (error) 1430 goto locked_error; 1431 #endif 1432 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) 1433 if (rpipe->pipe_pages.cnt > 0 || rpipe->pipe_buffer.cnt > 0) 1434 revents |= events & (POLLIN | POLLRDNORM); 1435 1436 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) 1437 if (wpipe->pipe_present != PIPE_ACTIVE || 1438 (wpipe->pipe_state & PIPE_EOF) || 1439 ((wpipe->pipe_state & PIPE_DIRECTW) == 0 && 1440 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF || 1441 wpipe->pipe_buffer.size == 0))) 1442 revents |= events & (POLLOUT | POLLWRNORM); 1443 1444 levents = events & 1445 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND); 1446 if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents && 1447 fp->f_pipegen == rpipe->pipe_wgen) 1448 events |= POLLINIGNEOF; 1449 1450 if ((events & POLLINIGNEOF) == 0) { 1451 if (rpipe->pipe_state & PIPE_EOF) { 1452 if (fp->f_flag & FREAD) 1453 revents |= (events & (POLLIN | POLLRDNORM)); 1454 if (wpipe->pipe_present != PIPE_ACTIVE || 1455 (wpipe->pipe_state & PIPE_EOF)) 1456 revents |= POLLHUP; 1457 } 1458 } 1459 1460 if (revents == 0) { 1461 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) { 1462 selrecord(td, &rpipe->pipe_sel); 1463 if (SEL_WAITING(&rpipe->pipe_sel)) 1464 rpipe->pipe_state |= PIPE_SEL; 1465 } 1466 1467 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) { 1468 selrecord(td, &wpipe->pipe_sel); 1469 if (SEL_WAITING(&wpipe->pipe_sel)) 1470 wpipe->pipe_state |= PIPE_SEL; 1471 } 1472 } 1473 #ifdef MAC 1474 locked_error: 1475 #endif 1476 PIPE_UNLOCK(rpipe); 1477 1478 return (revents); 1479 } 1480 1481 /* 1482 * We shouldn't need locks here as we're doing a read and this should 1483 * be a natural race. 1484 */ 1485 static int 1486 pipe_stat(struct file *fp, struct stat *ub, struct ucred *active_cred, 1487 struct thread *td) 1488 { 1489 struct pipe *pipe; 1490 #ifdef MAC 1491 int error; 1492 #endif 1493 1494 pipe = fp->f_data; 1495 PIPE_LOCK(pipe); 1496 #ifdef MAC 1497 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair); 1498 if (error) { 1499 PIPE_UNLOCK(pipe); 1500 return (error); 1501 } 1502 #endif 1503 1504 /* For named pipes ask the underlying filesystem. */ 1505 if (pipe->pipe_state & PIPE_NAMED) { 1506 PIPE_UNLOCK(pipe); 1507 return (vnops.fo_stat(fp, ub, active_cred, td)); 1508 } 1509 1510 PIPE_UNLOCK(pipe); 1511 1512 bzero(ub, sizeof(*ub)); 1513 ub->st_mode = S_IFIFO; 1514 ub->st_blksize = PAGE_SIZE; 1515 if (pipe->pipe_pages.cnt != 0) 1516 ub->st_size = pipe->pipe_pages.cnt; 1517 else 1518 ub->st_size = pipe->pipe_buffer.cnt; 1519 ub->st_blocks = howmany(ub->st_size, ub->st_blksize); 1520 ub->st_atim = pipe->pipe_atime; 1521 ub->st_mtim = pipe->pipe_mtime; 1522 ub->st_ctim = pipe->pipe_ctime; 1523 ub->st_uid = fp->f_cred->cr_uid; 1524 ub->st_gid = fp->f_cred->cr_gid; 1525 ub->st_dev = pipedev_ino; 1526 ub->st_ino = pipe->pipe_ino; 1527 /* 1528 * Left as 0: st_nlink, st_rdev, st_flags, st_gen. 1529 */ 1530 return (0); 1531 } 1532 1533 /* ARGSUSED */ 1534 static int 1535 pipe_close(struct file *fp, struct thread *td) 1536 { 1537 1538 if (fp->f_vnode != NULL) 1539 return vnops.fo_close(fp, td); 1540 fp->f_ops = &badfileops; 1541 pipe_dtor(fp->f_data); 1542 fp->f_data = NULL; 1543 return (0); 1544 } 1545 1546 static int 1547 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td) 1548 { 1549 struct pipe *cpipe; 1550 int error; 1551 1552 cpipe = fp->f_data; 1553 if (cpipe->pipe_state & PIPE_NAMED) 1554 error = vn_chmod(fp, mode, active_cred, td); 1555 else 1556 error = invfo_chmod(fp, mode, active_cred, td); 1557 return (error); 1558 } 1559 1560 static int 1561 pipe_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1562 struct thread *td) 1563 { 1564 struct pipe *cpipe; 1565 int error; 1566 1567 cpipe = fp->f_data; 1568 if (cpipe->pipe_state & PIPE_NAMED) 1569 error = vn_chown(fp, uid, gid, active_cred, td); 1570 else 1571 error = invfo_chown(fp, uid, gid, active_cred, td); 1572 return (error); 1573 } 1574 1575 static int 1576 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp) 1577 { 1578 struct pipe *pi; 1579 1580 if (fp->f_type == DTYPE_FIFO) 1581 return (vn_fill_kinfo(fp, kif, fdp)); 1582 kif->kf_type = KF_TYPE_PIPE; 1583 pi = fp->f_data; 1584 kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi; 1585 kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer; 1586 kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt; 1587 return (0); 1588 } 1589 1590 static void 1591 pipe_free_kmem(struct pipe *cpipe) 1592 { 1593 1594 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), 1595 ("pipe_free_kmem: pipe mutex locked")); 1596 1597 if (cpipe->pipe_buffer.buffer != NULL) { 1598 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size); 1599 vm_map_remove(pipe_map, 1600 (vm_offset_t)cpipe->pipe_buffer.buffer, 1601 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size); 1602 cpipe->pipe_buffer.buffer = NULL; 1603 } 1604 #ifndef PIPE_NODIRECT 1605 { 1606 cpipe->pipe_pages.cnt = 0; 1607 cpipe->pipe_pages.pos = 0; 1608 cpipe->pipe_pages.npages = 0; 1609 } 1610 #endif 1611 } 1612 1613 /* 1614 * shutdown the pipe 1615 */ 1616 static void 1617 pipeclose(struct pipe *cpipe) 1618 { 1619 struct pipepair *pp; 1620 struct pipe *ppipe; 1621 1622 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL")); 1623 1624 PIPE_LOCK(cpipe); 1625 pipelock(cpipe, 0); 1626 pp = cpipe->pipe_pair; 1627 1628 /* 1629 * If the other side is blocked, wake it up saying that 1630 * we want to close it down. 1631 */ 1632 cpipe->pipe_state |= PIPE_EOF; 1633 while (cpipe->pipe_busy) { 1634 wakeup(cpipe); 1635 cpipe->pipe_state |= PIPE_WANT; 1636 pipeunlock(cpipe); 1637 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0); 1638 pipelock(cpipe, 0); 1639 } 1640 1641 pipeselwakeup(cpipe); 1642 1643 /* 1644 * Disconnect from peer, if any. 1645 */ 1646 ppipe = cpipe->pipe_peer; 1647 if (ppipe->pipe_present == PIPE_ACTIVE) { 1648 ppipe->pipe_state |= PIPE_EOF; 1649 wakeup(ppipe); 1650 pipeselwakeup(ppipe); 1651 } 1652 1653 /* 1654 * Mark this endpoint as free. Release kmem resources. We 1655 * don't mark this endpoint as unused until we've finished 1656 * doing that, or the pipe might disappear out from under 1657 * us. 1658 */ 1659 PIPE_UNLOCK(cpipe); 1660 pipe_free_kmem(cpipe); 1661 PIPE_LOCK(cpipe); 1662 cpipe->pipe_present = PIPE_CLOSING; 1663 pipeunlock(cpipe); 1664 1665 /* 1666 * knlist_clear() may sleep dropping the PIPE_MTX. Set the 1667 * PIPE_FINALIZED, that allows other end to free the 1668 * pipe_pair, only after the knotes are completely dismantled. 1669 */ 1670 knlist_clear(&cpipe->pipe_sel.si_note, 1); 1671 cpipe->pipe_present = PIPE_FINALIZED; 1672 seldrain(&cpipe->pipe_sel); 1673 knlist_destroy(&cpipe->pipe_sel.si_note); 1674 1675 /* 1676 * If both endpoints are now closed, release the memory for the 1677 * pipe pair. If not, unlock. 1678 */ 1679 if (ppipe->pipe_present == PIPE_FINALIZED) { 1680 PIPE_UNLOCK(cpipe); 1681 #ifdef MAC 1682 mac_pipe_destroy(pp); 1683 #endif 1684 uma_zfree(pipe_zone, cpipe->pipe_pair); 1685 } else 1686 PIPE_UNLOCK(cpipe); 1687 } 1688 1689 /*ARGSUSED*/ 1690 static int 1691 pipe_kqfilter(struct file *fp, struct knote *kn) 1692 { 1693 struct pipe *cpipe; 1694 1695 /* 1696 * If a filter is requested that is not supported by this file 1697 * descriptor, don't return an error, but also don't ever generate an 1698 * event. 1699 */ 1700 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) { 1701 kn->kn_fop = &pipe_nfiltops; 1702 return (0); 1703 } 1704 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) { 1705 kn->kn_fop = &pipe_nfiltops; 1706 return (0); 1707 } 1708 cpipe = fp->f_data; 1709 PIPE_LOCK(cpipe); 1710 switch (kn->kn_filter) { 1711 case EVFILT_READ: 1712 kn->kn_fop = &pipe_rfiltops; 1713 break; 1714 case EVFILT_WRITE: 1715 kn->kn_fop = &pipe_wfiltops; 1716 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) { 1717 /* other end of pipe has been closed */ 1718 PIPE_UNLOCK(cpipe); 1719 return (EPIPE); 1720 } 1721 cpipe = PIPE_PEER(cpipe); 1722 break; 1723 default: 1724 PIPE_UNLOCK(cpipe); 1725 return (EINVAL); 1726 } 1727 1728 kn->kn_hook = cpipe; 1729 knlist_add(&cpipe->pipe_sel.si_note, kn, 1); 1730 PIPE_UNLOCK(cpipe); 1731 return (0); 1732 } 1733 1734 static void 1735 filt_pipedetach(struct knote *kn) 1736 { 1737 struct pipe *cpipe = kn->kn_hook; 1738 1739 PIPE_LOCK(cpipe); 1740 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1); 1741 PIPE_UNLOCK(cpipe); 1742 } 1743 1744 /*ARGSUSED*/ 1745 static int 1746 filt_piperead(struct knote *kn, long hint) 1747 { 1748 struct file *fp = kn->kn_fp; 1749 struct pipe *rpipe = kn->kn_hook; 1750 1751 PIPE_LOCK_ASSERT(rpipe, MA_OWNED); 1752 kn->kn_data = rpipe->pipe_buffer.cnt; 1753 if (kn->kn_data == 0) 1754 kn->kn_data = rpipe->pipe_pages.cnt; 1755 1756 if ((rpipe->pipe_state & PIPE_EOF) != 0 && 1757 ((rpipe->pipe_state & PIPE_NAMED) == 0 || 1758 fp->f_pipegen != rpipe->pipe_wgen)) { 1759 kn->kn_flags |= EV_EOF; 1760 return (1); 1761 } 1762 kn->kn_flags &= ~EV_EOF; 1763 return (kn->kn_data > 0); 1764 } 1765 1766 /*ARGSUSED*/ 1767 static int 1768 filt_pipewrite(struct knote *kn, long hint) 1769 { 1770 struct pipe *wpipe = kn->kn_hook; 1771 1772 /* 1773 * If this end of the pipe is closed, the knote was removed from the 1774 * knlist and the list lock (i.e., the pipe lock) is therefore not held. 1775 */ 1776 if (wpipe->pipe_present == PIPE_ACTIVE || 1777 (wpipe->pipe_state & PIPE_NAMED) != 0) { 1778 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 1779 1780 if (wpipe->pipe_state & PIPE_DIRECTW) { 1781 kn->kn_data = 0; 1782 } else if (wpipe->pipe_buffer.size > 0) { 1783 kn->kn_data = wpipe->pipe_buffer.size - 1784 wpipe->pipe_buffer.cnt; 1785 } else { 1786 kn->kn_data = PIPE_BUF; 1787 } 1788 } 1789 1790 if (wpipe->pipe_present != PIPE_ACTIVE || 1791 (wpipe->pipe_state & PIPE_EOF)) { 1792 kn->kn_flags |= EV_EOF; 1793 return (1); 1794 } 1795 kn->kn_flags &= ~EV_EOF; 1796 return (kn->kn_data >= PIPE_BUF); 1797 } 1798 1799 static void 1800 filt_pipedetach_notsup(struct knote *kn) 1801 { 1802 1803 } 1804 1805 static int 1806 filt_pipenotsup(struct knote *kn, long hint) 1807 { 1808 1809 return (0); 1810 } 1811