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