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