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 * Copyright (c) 1996 John S. Dyson 3 * Copyright (c) 2012 Giovanni Trematerra 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice immediately at the beginning of the file, without modification, 11 * this list of conditions, and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Absolutely no warranty of function or purpose is made by the author 16 * John S. Dyson. 17 * 4. Modifications may be freely made to this file if the above conditions 18 * are met. 19 */ 20 21 /* 22 * This file contains a high-performance replacement for the socket-based 23 * pipes scheme originally used in FreeBSD/4.4Lite. It does not support 24 * all features of sockets, but does do everything that pipes normally 25 * do. 26 */ 27 28 /* 29 * This code has two modes of operation, a small write mode and a large 30 * write mode. The small write mode acts like conventional pipes with 31 * a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the 32 * "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT 33 * and PIPE_SIZE in size, the sending process pins the underlying pages in 34 * memory, and the receiving process copies directly from these pinned pages 35 * in the sending process. 36 * 37 * If the sending process receives a signal, it is possible that it will 38 * go away, and certainly its address space can change, because control 39 * is returned back to the user-mode side. In that case, the pipe code 40 * arranges to copy the buffer supplied by the user process, to a pageable 41 * kernel buffer, and the receiving process will grab the data from the 42 * pageable kernel buffer. Since signals don't happen all that often, 43 * the copy operation is normally eliminated. 44 * 45 * The constant PIPE_MINDIRECT is chosen to make sure that buffering will 46 * happen for small transfers so that the system will not spend all of 47 * its time context switching. 48 * 49 * In order to limit the resource use of pipes, two sysctls exist: 50 * 51 * kern.ipc.maxpipekva - This is a hard limit on the amount of pageable 52 * address space available to us in pipe_map. This value is normally 53 * autotuned, but may also be loader tuned. 54 * 55 * kern.ipc.pipekva - This read-only sysctl tracks the current amount of 56 * memory in use by pipes. 57 * 58 * Based on how large pipekva is relative to maxpipekva, the following 59 * will happen: 60 * 61 * 0% - 50%: 62 * New pipes are given 16K of memory backing, pipes may dynamically 63 * grow to as large as 64K where needed. 64 * 50% - 75%: 65 * New pipes are given 4K (or PAGE_SIZE) of memory backing, 66 * existing pipes may NOT grow. 67 * 75% - 100%: 68 * New pipes are given 4K (or PAGE_SIZE) of memory backing, 69 * existing pipes will be shrunk down to 4K whenever possible. 70 * 71 * Resizing may be disabled by setting kern.ipc.piperesizeallowed=0. If 72 * that is set, the only resize that will occur is the 0 -> SMALL_PIPE_SIZE 73 * resize which MUST occur for reverse-direction pipes when they are 74 * first used. 75 * 76 * Additional information about the current state of pipes may be obtained 77 * from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail, 78 * and kern.ipc.piperesizefail. 79 * 80 * Locking rules: There are two locks present here: A mutex, used via 81 * PIPE_LOCK, and a flag, used via pipelock(). All locking is done via 82 * the flag, as mutexes can not persist over uiomove. The mutex 83 * exists only to guard access to the flag, and is not in itself a 84 * locking mechanism. Also note that there is only a single mutex for 85 * both directions of a pipe. 86 * 87 * As pipelock() may have to sleep before it can acquire the flag, it 88 * is important to reread all data after a call to pipelock(); everything 89 * in the structure may have changed. 90 */ 91 92 #include "opt_compat.h" 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 void pipe_create(struct pipe *pipe, int backing); 230 static void 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 unrhdr *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 pipeino_unr = new_unrhdr(1, INT32_MAX, NULL); 261 KASSERT(pipeino_unr != NULL, ("pipe fake inodes not initialized")); 262 pipedev_ino = devfs_alloc_cdp_inode(); 263 KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized")); 264 } 265 266 static int 267 pipe_zone_ctor(void *mem, int size, void *arg, int flags) 268 { 269 struct pipepair *pp; 270 struct pipe *rpipe, *wpipe; 271 272 KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size")); 273 274 pp = (struct pipepair *)mem; 275 276 /* 277 * We zero both pipe endpoints to make sure all the kmem pointers 278 * are NULL, flag fields are zero'd, etc. We timestamp both 279 * endpoints with the same time. 280 */ 281 rpipe = &pp->pp_rpipe; 282 bzero(rpipe, sizeof(*rpipe)); 283 vfs_timestamp(&rpipe->pipe_ctime); 284 rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime; 285 286 wpipe = &pp->pp_wpipe; 287 bzero(wpipe, sizeof(*wpipe)); 288 wpipe->pipe_ctime = rpipe->pipe_ctime; 289 wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime; 290 291 rpipe->pipe_peer = wpipe; 292 rpipe->pipe_pair = pp; 293 wpipe->pipe_peer = rpipe; 294 wpipe->pipe_pair = pp; 295 296 /* 297 * Mark both endpoints as present; they will later get free'd 298 * one at a time. When both are free'd, then the whole pair 299 * is released. 300 */ 301 rpipe->pipe_present = PIPE_ACTIVE; 302 wpipe->pipe_present = PIPE_ACTIVE; 303 304 /* 305 * Eventually, the MAC Framework may initialize the label 306 * in ctor or init, but for now we do it elswhere to avoid 307 * blocking in ctor or init. 308 */ 309 pp->pp_label = NULL; 310 311 return (0); 312 } 313 314 static int 315 pipe_zone_init(void *mem, int size, int flags) 316 { 317 struct pipepair *pp; 318 319 KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size")); 320 321 pp = (struct pipepair *)mem; 322 323 mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_NEW); 324 return (0); 325 } 326 327 static void 328 pipe_zone_fini(void *mem, int size) 329 { 330 struct pipepair *pp; 331 332 KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size")); 333 334 pp = (struct pipepair *)mem; 335 336 mtx_destroy(&pp->pp_mtx); 337 } 338 339 static void 340 pipe_paircreate(struct thread *td, struct pipepair **p_pp) 341 { 342 struct pipepair *pp; 343 struct pipe *rpipe, *wpipe; 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 /* Only the forward direction pipe is backed by default */ 362 pipe_create(rpipe, 1); 363 pipe_create(wpipe, 0); 364 365 rpipe->pipe_state |= PIPE_DIRECTOK; 366 wpipe->pipe_state |= PIPE_DIRECTOK; 367 } 368 369 void 370 pipe_named_ctor(struct pipe **ppipe, struct thread *td) 371 { 372 struct pipepair *pp; 373 374 pipe_paircreate(td, &pp); 375 pp->pp_rpipe.pipe_state |= PIPE_NAMED; 376 *ppipe = &pp->pp_rpipe; 377 } 378 379 void 380 pipe_dtor(struct pipe *dpipe) 381 { 382 struct pipe *peer; 383 ino_t ino; 384 385 ino = dpipe->pipe_ino; 386 peer = (dpipe->pipe_state & PIPE_NAMED) != 0 ? dpipe->pipe_peer : NULL; 387 funsetown(&dpipe->pipe_sigio); 388 pipeclose(dpipe); 389 if (peer != NULL) { 390 funsetown(&peer->pipe_sigio); 391 pipeclose(peer); 392 } 393 if (ino != 0 && ino != (ino_t)-1) 394 free_unr(pipeino_unr, ino); 395 } 396 397 /* 398 * The pipe system call for the DTYPE_PIPE type of pipes. If we fail, let 399 * the zone pick up the pieces via pipeclose(). 400 */ 401 int 402 kern_pipe(struct thread *td, int fildes[2], int flags, struct filecaps *fcaps1, 403 struct filecaps *fcaps2) 404 { 405 struct file *rf, *wf; 406 struct pipe *rpipe, *wpipe; 407 struct pipepair *pp; 408 int fd, fflags, error; 409 410 pipe_paircreate(td, &pp); 411 rpipe = &pp->pp_rpipe; 412 wpipe = &pp->pp_wpipe; 413 error = falloc_caps(td, &rf, &fd, flags, fcaps1); 414 if (error) { 415 pipeclose(rpipe); 416 pipeclose(wpipe); 417 return (error); 418 } 419 /* An extra reference on `rf' has been held for us by falloc_caps(). */ 420 fildes[0] = fd; 421 422 fflags = FREAD | FWRITE; 423 if ((flags & O_NONBLOCK) != 0) 424 fflags |= FNONBLOCK; 425 426 /* 427 * Warning: once we've gotten past allocation of the fd for the 428 * read-side, we can only drop the read side via fdrop() in order 429 * to avoid races against processes which manage to dup() the read 430 * side while we are blocked trying to allocate the write side. 431 */ 432 finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops); 433 error = falloc_caps(td, &wf, &fd, flags, fcaps2); 434 if (error) { 435 fdclose(td, rf, fildes[0]); 436 fdrop(rf, td); 437 /* rpipe has been closed by fdrop(). */ 438 pipeclose(wpipe); 439 return (error); 440 } 441 /* An extra reference on `wf' has been held for us by falloc_caps(). */ 442 finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops); 443 fdrop(wf, td); 444 fildes[1] = fd; 445 fdrop(rf, td); 446 447 return (0); 448 } 449 450 #ifdef COMPAT_FREEBSD10 451 /* ARGSUSED */ 452 int 453 freebsd10_pipe(struct thread *td, struct freebsd10_pipe_args *uap __unused) 454 { 455 int error; 456 int fildes[2]; 457 458 error = kern_pipe(td, fildes, 0, NULL, NULL); 459 if (error) 460 return (error); 461 462 td->td_retval[0] = fildes[0]; 463 td->td_retval[1] = fildes[1]; 464 465 return (0); 466 } 467 #endif 468 469 int 470 sys_pipe2(struct thread *td, struct pipe2_args *uap) 471 { 472 int error, fildes[2]; 473 474 if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK)) 475 return (EINVAL); 476 error = kern_pipe(td, fildes, uap->flags, NULL, NULL); 477 if (error) 478 return (error); 479 error = copyout(fildes, uap->fildes, 2 * sizeof(int)); 480 if (error) { 481 (void)kern_close(td, fildes[0]); 482 (void)kern_close(td, fildes[1]); 483 } 484 return (error); 485 } 486 487 /* 488 * Allocate kva for pipe circular buffer, the space is pageable 489 * This routine will 'realloc' the size of a pipe safely, if it fails 490 * it will retain the old buffer. 491 * If it fails it will return ENOMEM. 492 */ 493 static int 494 pipespace_new(cpipe, size) 495 struct pipe *cpipe; 496 int size; 497 { 498 caddr_t buffer; 499 int error, cnt, firstseg; 500 static int curfail = 0; 501 static struct timeval lastfail; 502 503 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked")); 504 KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW), 505 ("pipespace: resize of direct writes not allowed")); 506 retry: 507 cnt = cpipe->pipe_buffer.cnt; 508 if (cnt > size) 509 size = cnt; 510 511 size = round_page(size); 512 buffer = (caddr_t) vm_map_min(pipe_map); 513 514 error = vm_map_find(pipe_map, NULL, 0, (vm_offset_t *)&buffer, size, 0, 515 VMFS_ANY_SPACE, VM_PROT_RW, VM_PROT_RW, 0); 516 if (error != KERN_SUCCESS) { 517 if ((cpipe->pipe_buffer.buffer == NULL) && 518 (size > SMALL_PIPE_SIZE)) { 519 size = SMALL_PIPE_SIZE; 520 pipefragretry++; 521 goto retry; 522 } 523 if (cpipe->pipe_buffer.buffer == NULL) { 524 pipeallocfail++; 525 if (ppsratecheck(&lastfail, &curfail, 1)) 526 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n"); 527 } else { 528 piperesizefail++; 529 } 530 return (ENOMEM); 531 } 532 533 /* copy data, then free old resources if we're resizing */ 534 if (cnt > 0) { 535 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) { 536 firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out; 537 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 538 buffer, firstseg); 539 if ((cnt - firstseg) > 0) 540 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg], 541 cpipe->pipe_buffer.in); 542 } else { 543 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 544 buffer, cnt); 545 } 546 } 547 pipe_free_kmem(cpipe); 548 cpipe->pipe_buffer.buffer = buffer; 549 cpipe->pipe_buffer.size = size; 550 cpipe->pipe_buffer.in = cnt; 551 cpipe->pipe_buffer.out = 0; 552 cpipe->pipe_buffer.cnt = cnt; 553 atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size); 554 return (0); 555 } 556 557 /* 558 * Wrapper for pipespace_new() that performs locking assertions. 559 */ 560 static int 561 pipespace(cpipe, size) 562 struct pipe *cpipe; 563 int size; 564 { 565 566 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 567 ("Unlocked pipe passed to pipespace")); 568 return (pipespace_new(cpipe, size)); 569 } 570 571 /* 572 * lock a pipe for I/O, blocking other access 573 */ 574 static __inline int 575 pipelock(cpipe, catch) 576 struct pipe *cpipe; 577 int catch; 578 { 579 int error; 580 581 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 582 while (cpipe->pipe_state & PIPE_LOCKFL) { 583 cpipe->pipe_state |= PIPE_LWANT; 584 error = msleep(cpipe, PIPE_MTX(cpipe), 585 catch ? (PRIBIO | PCATCH) : PRIBIO, 586 "pipelk", 0); 587 if (error != 0) 588 return (error); 589 } 590 cpipe->pipe_state |= PIPE_LOCKFL; 591 return (0); 592 } 593 594 /* 595 * unlock a pipe I/O lock 596 */ 597 static __inline void 598 pipeunlock(cpipe) 599 struct pipe *cpipe; 600 { 601 602 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 603 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 604 ("Unlocked pipe passed to pipeunlock")); 605 cpipe->pipe_state &= ~PIPE_LOCKFL; 606 if (cpipe->pipe_state & PIPE_LWANT) { 607 cpipe->pipe_state &= ~PIPE_LWANT; 608 wakeup(cpipe); 609 } 610 } 611 612 void 613 pipeselwakeup(cpipe) 614 struct pipe *cpipe; 615 { 616 617 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 618 if (cpipe->pipe_state & PIPE_SEL) { 619 selwakeuppri(&cpipe->pipe_sel, PSOCK); 620 if (!SEL_WAITING(&cpipe->pipe_sel)) 621 cpipe->pipe_state &= ~PIPE_SEL; 622 } 623 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) 624 pgsigio(&cpipe->pipe_sigio, SIGIO, 0); 625 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0); 626 } 627 628 /* 629 * Initialize and allocate VM and memory for pipe. The structure 630 * will start out zero'd from the ctor, so we just manage the kmem. 631 */ 632 static void 633 pipe_create(pipe, backing) 634 struct pipe *pipe; 635 int backing; 636 { 637 638 if (backing) { 639 /* 640 * Note that these functions can fail if pipe map is exhausted 641 * (as a result of too many pipes created), but we ignore the 642 * error as it is not fatal and could be provoked by 643 * unprivileged users. The only consequence is worse performance 644 * with given pipe. 645 */ 646 if (amountpipekva > maxpipekva / 2) 647 (void)pipespace_new(pipe, SMALL_PIPE_SIZE); 648 else 649 (void)pipespace_new(pipe, PIPE_SIZE); 650 } 651 652 pipe->pipe_ino = -1; 653 } 654 655 /* ARGSUSED */ 656 static int 657 pipe_read(fp, uio, active_cred, flags, td) 658 struct file *fp; 659 struct uio *uio; 660 struct ucred *active_cred; 661 struct thread *td; 662 int flags; 663 { 664 struct pipe *rpipe; 665 int error; 666 int nread = 0; 667 int size; 668 669 rpipe = fp->f_data; 670 PIPE_LOCK(rpipe); 671 ++rpipe->pipe_busy; 672 error = pipelock(rpipe, 1); 673 if (error) 674 goto unlocked_error; 675 676 #ifdef MAC 677 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair); 678 if (error) 679 goto locked_error; 680 #endif 681 if (amountpipekva > (3 * maxpipekva) / 4) { 682 if (!(rpipe->pipe_state & PIPE_DIRECTW) && 683 (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) && 684 (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) && 685 (piperesizeallowed == 1)) { 686 PIPE_UNLOCK(rpipe); 687 pipespace(rpipe, SMALL_PIPE_SIZE); 688 PIPE_LOCK(rpipe); 689 } 690 } 691 692 while (uio->uio_resid) { 693 /* 694 * normal pipe buffer receive 695 */ 696 if (rpipe->pipe_buffer.cnt > 0) { 697 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 698 if (size > rpipe->pipe_buffer.cnt) 699 size = rpipe->pipe_buffer.cnt; 700 if (size > uio->uio_resid) 701 size = uio->uio_resid; 702 703 PIPE_UNLOCK(rpipe); 704 error = uiomove( 705 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 706 size, uio); 707 PIPE_LOCK(rpipe); 708 if (error) 709 break; 710 711 rpipe->pipe_buffer.out += size; 712 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 713 rpipe->pipe_buffer.out = 0; 714 715 rpipe->pipe_buffer.cnt -= size; 716 717 /* 718 * If there is no more to read in the pipe, reset 719 * its pointers to the beginning. This improves 720 * cache hit stats. 721 */ 722 if (rpipe->pipe_buffer.cnt == 0) { 723 rpipe->pipe_buffer.in = 0; 724 rpipe->pipe_buffer.out = 0; 725 } 726 nread += size; 727 #ifndef PIPE_NODIRECT 728 /* 729 * Direct copy, bypassing a kernel buffer. 730 */ 731 } else if ((size = rpipe->pipe_map.cnt) && 732 (rpipe->pipe_state & PIPE_DIRECTW)) { 733 if (size > uio->uio_resid) 734 size = (u_int) uio->uio_resid; 735 736 PIPE_UNLOCK(rpipe); 737 error = uiomove_fromphys(rpipe->pipe_map.ms, 738 rpipe->pipe_map.pos, size, uio); 739 PIPE_LOCK(rpipe); 740 if (error) 741 break; 742 nread += size; 743 rpipe->pipe_map.pos += size; 744 rpipe->pipe_map.cnt -= size; 745 if (rpipe->pipe_map.cnt == 0) { 746 rpipe->pipe_state &= ~PIPE_WANTW; 747 wakeup(rpipe); 748 } 749 #endif 750 } else { 751 /* 752 * detect EOF condition 753 * read returns 0 on EOF, no need to set error 754 */ 755 if (rpipe->pipe_state & PIPE_EOF) 756 break; 757 758 /* 759 * If the "write-side" has been blocked, wake it up now. 760 */ 761 if (rpipe->pipe_state & PIPE_WANTW) { 762 rpipe->pipe_state &= ~PIPE_WANTW; 763 wakeup(rpipe); 764 } 765 766 /* 767 * Break if some data was read. 768 */ 769 if (nread > 0) 770 break; 771 772 /* 773 * Unlock the pipe buffer for our remaining processing. 774 * We will either break out with an error or we will 775 * sleep and relock to loop. 776 */ 777 pipeunlock(rpipe); 778 779 /* 780 * Handle non-blocking mode operation or 781 * wait for more data. 782 */ 783 if (fp->f_flag & FNONBLOCK) { 784 error = EAGAIN; 785 } else { 786 rpipe->pipe_state |= PIPE_WANTR; 787 if ((error = msleep(rpipe, PIPE_MTX(rpipe), 788 PRIBIO | PCATCH, 789 "piperd", 0)) == 0) 790 error = pipelock(rpipe, 1); 791 } 792 if (error) 793 goto unlocked_error; 794 } 795 } 796 #ifdef MAC 797 locked_error: 798 #endif 799 pipeunlock(rpipe); 800 801 /* XXX: should probably do this before getting any locks. */ 802 if (error == 0) 803 vfs_timestamp(&rpipe->pipe_atime); 804 unlocked_error: 805 --rpipe->pipe_busy; 806 807 /* 808 * PIPE_WANT processing only makes sense if pipe_busy is 0. 809 */ 810 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 811 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 812 wakeup(rpipe); 813 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 814 /* 815 * Handle write blocking hysteresis. 816 */ 817 if (rpipe->pipe_state & PIPE_WANTW) { 818 rpipe->pipe_state &= ~PIPE_WANTW; 819 wakeup(rpipe); 820 } 821 } 822 823 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF) 824 pipeselwakeup(rpipe); 825 826 PIPE_UNLOCK(rpipe); 827 return (error); 828 } 829 830 #ifndef PIPE_NODIRECT 831 /* 832 * Map the sending processes' buffer into kernel space and wire it. 833 * This is similar to a physical write operation. 834 */ 835 static int 836 pipe_build_write_buffer(wpipe, uio) 837 struct pipe *wpipe; 838 struct uio *uio; 839 { 840 u_int size; 841 int i; 842 843 PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED); 844 KASSERT(wpipe->pipe_state & PIPE_DIRECTW, 845 ("Clone attempt on non-direct write pipe!")); 846 847 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size) 848 size = wpipe->pipe_buffer.size; 849 else 850 size = uio->uio_iov->iov_len; 851 852 if ((i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 853 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ, 854 wpipe->pipe_map.ms, PIPENPAGES)) < 0) 855 return (EFAULT); 856 857 /* 858 * set up the control block 859 */ 860 wpipe->pipe_map.npages = i; 861 wpipe->pipe_map.pos = 862 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 863 wpipe->pipe_map.cnt = size; 864 865 /* 866 * and update the uio data 867 */ 868 869 uio->uio_iov->iov_len -= size; 870 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size; 871 if (uio->uio_iov->iov_len == 0) 872 uio->uio_iov++; 873 uio->uio_resid -= size; 874 uio->uio_offset += size; 875 return (0); 876 } 877 878 /* 879 * Unwire the process buffer. 880 */ 881 static void 882 pipe_destroy_write_buffer(wpipe) 883 struct pipe *wpipe; 884 { 885 886 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 887 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0, 888 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe)); 889 890 wpipe->pipe_state &= ~PIPE_DIRECTW; 891 vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages); 892 wpipe->pipe_map.npages = 0; 893 } 894 895 /* 896 * In the case of a signal, the writing process might go away. This 897 * code copies the data into the circular buffer so that the source 898 * pages can be freed without loss of data. 899 */ 900 static void 901 pipe_clone_write_buffer(wpipe) 902 struct pipe *wpipe; 903 { 904 struct uio uio; 905 struct iovec iov; 906 int size; 907 int pos; 908 909 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 910 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0, 911 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe)); 912 913 size = wpipe->pipe_map.cnt; 914 pos = wpipe->pipe_map.pos; 915 916 wpipe->pipe_buffer.in = size; 917 wpipe->pipe_buffer.out = 0; 918 wpipe->pipe_buffer.cnt = size; 919 920 PIPE_UNLOCK(wpipe); 921 iov.iov_base = wpipe->pipe_buffer.buffer; 922 iov.iov_len = size; 923 uio.uio_iov = &iov; 924 uio.uio_iovcnt = 1; 925 uio.uio_offset = 0; 926 uio.uio_resid = size; 927 uio.uio_segflg = UIO_SYSSPACE; 928 uio.uio_rw = UIO_READ; 929 uio.uio_td = curthread; 930 uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio); 931 PIPE_LOCK(wpipe); 932 pipe_destroy_write_buffer(wpipe); 933 } 934 935 /* 936 * This implements the pipe buffer write mechanism. Note that only 937 * a direct write OR a normal pipe write can be pending at any given time. 938 * If there are any characters in the pipe buffer, the direct write will 939 * be deferred until the receiving process grabs all of the bytes from 940 * the pipe buffer. Then the direct mapping write is set-up. 941 */ 942 static int 943 pipe_direct_write(wpipe, uio) 944 struct pipe *wpipe; 945 struct uio *uio; 946 { 947 int error; 948 949 retry: 950 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 951 error = pipelock(wpipe, 1); 952 if (error != 0) 953 goto error1; 954 if ((wpipe->pipe_state & PIPE_EOF) != 0) { 955 error = EPIPE; 956 pipeunlock(wpipe); 957 goto error1; 958 } 959 if (wpipe->pipe_state & PIPE_DIRECTW) { 960 if (wpipe->pipe_state & PIPE_WANTR) { 961 wpipe->pipe_state &= ~PIPE_WANTR; 962 wakeup(wpipe); 963 } 964 pipeselwakeup(wpipe); 965 wpipe->pipe_state |= PIPE_WANTW; 966 pipeunlock(wpipe); 967 error = msleep(wpipe, PIPE_MTX(wpipe), 968 PRIBIO | PCATCH, "pipdww", 0); 969 if (error) 970 goto error1; 971 else 972 goto retry; 973 } 974 wpipe->pipe_map.cnt = 0; /* transfer not ready yet */ 975 if (wpipe->pipe_buffer.cnt > 0) { 976 if (wpipe->pipe_state & PIPE_WANTR) { 977 wpipe->pipe_state &= ~PIPE_WANTR; 978 wakeup(wpipe); 979 } 980 pipeselwakeup(wpipe); 981 wpipe->pipe_state |= PIPE_WANTW; 982 pipeunlock(wpipe); 983 error = msleep(wpipe, PIPE_MTX(wpipe), 984 PRIBIO | PCATCH, "pipdwc", 0); 985 if (error) 986 goto error1; 987 else 988 goto retry; 989 } 990 991 wpipe->pipe_state |= PIPE_DIRECTW; 992 993 PIPE_UNLOCK(wpipe); 994 error = pipe_build_write_buffer(wpipe, uio); 995 PIPE_LOCK(wpipe); 996 if (error) { 997 wpipe->pipe_state &= ~PIPE_DIRECTW; 998 pipeunlock(wpipe); 999 goto error1; 1000 } 1001 1002 while (wpipe->pipe_map.cnt != 0) { 1003 if (wpipe->pipe_state & PIPE_EOF) { 1004 pipe_destroy_write_buffer(wpipe); 1005 pipeselwakeup(wpipe); 1006 pipeunlock(wpipe); 1007 error = EPIPE; 1008 goto error1; 1009 } 1010 if (wpipe->pipe_state & PIPE_WANTR) { 1011 wpipe->pipe_state &= ~PIPE_WANTR; 1012 wakeup(wpipe); 1013 } 1014 pipeselwakeup(wpipe); 1015 wpipe->pipe_state |= PIPE_WANTW; 1016 pipeunlock(wpipe); 1017 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH, 1018 "pipdwt", 0); 1019 pipelock(wpipe, 0); 1020 if (error != 0) 1021 break; 1022 } 1023 1024 if (wpipe->pipe_state & PIPE_EOF) 1025 error = EPIPE; 1026 if (error == EINTR || error == ERESTART) 1027 pipe_clone_write_buffer(wpipe); 1028 else 1029 pipe_destroy_write_buffer(wpipe); 1030 pipeunlock(wpipe); 1031 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0, 1032 ("pipe %p leaked PIPE_DIRECTW", wpipe)); 1033 return (error); 1034 1035 error1: 1036 wakeup(wpipe); 1037 return (error); 1038 } 1039 #endif 1040 1041 static int 1042 pipe_write(fp, uio, active_cred, flags, td) 1043 struct file *fp; 1044 struct uio *uio; 1045 struct ucred *active_cred; 1046 struct thread *td; 1047 int flags; 1048 { 1049 int error = 0; 1050 int desiredsize; 1051 ssize_t orig_resid; 1052 struct pipe *wpipe, *rpipe; 1053 1054 rpipe = fp->f_data; 1055 wpipe = PIPE_PEER(rpipe); 1056 PIPE_LOCK(rpipe); 1057 error = pipelock(wpipe, 1); 1058 if (error) { 1059 PIPE_UNLOCK(rpipe); 1060 return (error); 1061 } 1062 /* 1063 * detect loss of pipe read side, issue SIGPIPE if lost. 1064 */ 1065 if (wpipe->pipe_present != PIPE_ACTIVE || 1066 (wpipe->pipe_state & PIPE_EOF)) { 1067 pipeunlock(wpipe); 1068 PIPE_UNLOCK(rpipe); 1069 return (EPIPE); 1070 } 1071 #ifdef MAC 1072 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair); 1073 if (error) { 1074 pipeunlock(wpipe); 1075 PIPE_UNLOCK(rpipe); 1076 return (error); 1077 } 1078 #endif 1079 ++wpipe->pipe_busy; 1080 1081 /* Choose a larger size if it's advantageous */ 1082 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size); 1083 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) { 1084 if (piperesizeallowed != 1) 1085 break; 1086 if (amountpipekva > maxpipekva / 2) 1087 break; 1088 if (desiredsize == BIG_PIPE_SIZE) 1089 break; 1090 desiredsize = desiredsize * 2; 1091 } 1092 1093 /* Choose a smaller size if we're in a OOM situation */ 1094 if ((amountpipekva > (3 * maxpipekva) / 4) && 1095 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) && 1096 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) && 1097 (piperesizeallowed == 1)) 1098 desiredsize = SMALL_PIPE_SIZE; 1099 1100 /* Resize if the above determined that a new size was necessary */ 1101 if ((desiredsize != wpipe->pipe_buffer.size) && 1102 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) { 1103 PIPE_UNLOCK(wpipe); 1104 pipespace(wpipe, desiredsize); 1105 PIPE_LOCK(wpipe); 1106 } 1107 if (wpipe->pipe_buffer.size == 0) { 1108 /* 1109 * This can only happen for reverse direction use of pipes 1110 * in a complete OOM situation. 1111 */ 1112 error = ENOMEM; 1113 --wpipe->pipe_busy; 1114 pipeunlock(wpipe); 1115 PIPE_UNLOCK(wpipe); 1116 return (error); 1117 } 1118 1119 pipeunlock(wpipe); 1120 1121 orig_resid = uio->uio_resid; 1122 1123 while (uio->uio_resid) { 1124 int space; 1125 1126 pipelock(wpipe, 0); 1127 if (wpipe->pipe_state & PIPE_EOF) { 1128 pipeunlock(wpipe); 1129 error = EPIPE; 1130 break; 1131 } 1132 #ifndef PIPE_NODIRECT 1133 /* 1134 * If the transfer is large, we can gain performance if 1135 * we do process-to-process copies directly. 1136 * If the write is non-blocking, we don't use the 1137 * direct write mechanism. 1138 * 1139 * The direct write mechanism will detect the reader going 1140 * away on us. 1141 */ 1142 if (uio->uio_segflg == UIO_USERSPACE && 1143 uio->uio_iov->iov_len >= PIPE_MINDIRECT && 1144 wpipe->pipe_buffer.size >= PIPE_MINDIRECT && 1145 (fp->f_flag & FNONBLOCK) == 0) { 1146 pipeunlock(wpipe); 1147 error = pipe_direct_write(wpipe, uio); 1148 if (error) 1149 break; 1150 continue; 1151 } 1152 #endif 1153 1154 /* 1155 * Pipe buffered writes cannot be coincidental with 1156 * direct writes. We wait until the currently executing 1157 * direct write is completed before we start filling the 1158 * pipe buffer. We break out if a signal occurs or the 1159 * reader goes away. 1160 */ 1161 if (wpipe->pipe_state & PIPE_DIRECTW) { 1162 if (wpipe->pipe_state & PIPE_WANTR) { 1163 wpipe->pipe_state &= ~PIPE_WANTR; 1164 wakeup(wpipe); 1165 } 1166 pipeselwakeup(wpipe); 1167 wpipe->pipe_state |= PIPE_WANTW; 1168 pipeunlock(wpipe); 1169 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH, 1170 "pipbww", 0); 1171 if (error) 1172 break; 1173 else 1174 continue; 1175 } 1176 1177 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1178 1179 /* Writes of size <= PIPE_BUF must be atomic. */ 1180 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 1181 space = 0; 1182 1183 if (space > 0) { 1184 int size; /* Transfer size */ 1185 int segsize; /* first segment to transfer */ 1186 1187 /* 1188 * Transfer size is minimum of uio transfer 1189 * and free space in pipe buffer. 1190 */ 1191 if (space > uio->uio_resid) 1192 size = uio->uio_resid; 1193 else 1194 size = space; 1195 /* 1196 * First segment to transfer is minimum of 1197 * transfer size and contiguous space in 1198 * pipe buffer. If first segment to transfer 1199 * is less than the transfer size, we've got 1200 * a wraparound in the buffer. 1201 */ 1202 segsize = wpipe->pipe_buffer.size - 1203 wpipe->pipe_buffer.in; 1204 if (segsize > size) 1205 segsize = size; 1206 1207 /* Transfer first segment */ 1208 1209 PIPE_UNLOCK(rpipe); 1210 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 1211 segsize, uio); 1212 PIPE_LOCK(rpipe); 1213 1214 if (error == 0 && segsize < size) { 1215 KASSERT(wpipe->pipe_buffer.in + segsize == 1216 wpipe->pipe_buffer.size, 1217 ("Pipe buffer wraparound disappeared")); 1218 /* 1219 * Transfer remaining part now, to 1220 * support atomic writes. Wraparound 1221 * happened. 1222 */ 1223 1224 PIPE_UNLOCK(rpipe); 1225 error = uiomove( 1226 &wpipe->pipe_buffer.buffer[0], 1227 size - segsize, uio); 1228 PIPE_LOCK(rpipe); 1229 } 1230 if (error == 0) { 1231 wpipe->pipe_buffer.in += size; 1232 if (wpipe->pipe_buffer.in >= 1233 wpipe->pipe_buffer.size) { 1234 KASSERT(wpipe->pipe_buffer.in == 1235 size - segsize + 1236 wpipe->pipe_buffer.size, 1237 ("Expected wraparound bad")); 1238 wpipe->pipe_buffer.in = size - segsize; 1239 } 1240 1241 wpipe->pipe_buffer.cnt += size; 1242 KASSERT(wpipe->pipe_buffer.cnt <= 1243 wpipe->pipe_buffer.size, 1244 ("Pipe buffer overflow")); 1245 } 1246 pipeunlock(wpipe); 1247 if (error != 0) 1248 break; 1249 } else { 1250 /* 1251 * If the "read-side" has been blocked, wake it up now. 1252 */ 1253 if (wpipe->pipe_state & PIPE_WANTR) { 1254 wpipe->pipe_state &= ~PIPE_WANTR; 1255 wakeup(wpipe); 1256 } 1257 1258 /* 1259 * don't block on non-blocking I/O 1260 */ 1261 if (fp->f_flag & FNONBLOCK) { 1262 error = EAGAIN; 1263 pipeunlock(wpipe); 1264 break; 1265 } 1266 1267 /* 1268 * We have no more space and have something to offer, 1269 * wake up select/poll. 1270 */ 1271 pipeselwakeup(wpipe); 1272 1273 wpipe->pipe_state |= PIPE_WANTW; 1274 pipeunlock(wpipe); 1275 error = msleep(wpipe, PIPE_MTX(rpipe), 1276 PRIBIO | PCATCH, "pipewr", 0); 1277 if (error != 0) 1278 break; 1279 } 1280 } 1281 1282 pipelock(wpipe, 0); 1283 --wpipe->pipe_busy; 1284 1285 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 1286 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 1287 wakeup(wpipe); 1288 } else if (wpipe->pipe_buffer.cnt > 0) { 1289 /* 1290 * If we have put any characters in the buffer, we wake up 1291 * the reader. 1292 */ 1293 if (wpipe->pipe_state & PIPE_WANTR) { 1294 wpipe->pipe_state &= ~PIPE_WANTR; 1295 wakeup(wpipe); 1296 } 1297 } 1298 1299 /* 1300 * Don't return EPIPE if any byte was written. 1301 * EINTR and other interrupts are handled by generic I/O layer. 1302 * Do not pretend that I/O succeeded for obvious user error 1303 * like EFAULT. 1304 */ 1305 if (uio->uio_resid != orig_resid && error == EPIPE) 1306 error = 0; 1307 1308 if (error == 0) 1309 vfs_timestamp(&wpipe->pipe_mtime); 1310 1311 /* 1312 * We have something to offer, 1313 * wake up select/poll. 1314 */ 1315 if (wpipe->pipe_buffer.cnt) 1316 pipeselwakeup(wpipe); 1317 1318 pipeunlock(wpipe); 1319 PIPE_UNLOCK(rpipe); 1320 return (error); 1321 } 1322 1323 /* ARGSUSED */ 1324 static int 1325 pipe_truncate(fp, length, active_cred, td) 1326 struct file *fp; 1327 off_t length; 1328 struct ucred *active_cred; 1329 struct thread *td; 1330 { 1331 struct pipe *cpipe; 1332 int error; 1333 1334 cpipe = fp->f_data; 1335 if (cpipe->pipe_state & PIPE_NAMED) 1336 error = vnops.fo_truncate(fp, length, active_cred, td); 1337 else 1338 error = invfo_truncate(fp, length, active_cred, td); 1339 return (error); 1340 } 1341 1342 /* 1343 * we implement a very minimal set of ioctls for compatibility with sockets. 1344 */ 1345 static int 1346 pipe_ioctl(fp, cmd, data, active_cred, td) 1347 struct file *fp; 1348 u_long cmd; 1349 void *data; 1350 struct ucred *active_cred; 1351 struct thread *td; 1352 { 1353 struct pipe *mpipe = fp->f_data; 1354 int error; 1355 1356 PIPE_LOCK(mpipe); 1357 1358 #ifdef MAC 1359 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data); 1360 if (error) { 1361 PIPE_UNLOCK(mpipe); 1362 return (error); 1363 } 1364 #endif 1365 1366 error = 0; 1367 switch (cmd) { 1368 1369 case FIONBIO: 1370 break; 1371 1372 case FIOASYNC: 1373 if (*(int *)data) { 1374 mpipe->pipe_state |= PIPE_ASYNC; 1375 } else { 1376 mpipe->pipe_state &= ~PIPE_ASYNC; 1377 } 1378 break; 1379 1380 case FIONREAD: 1381 if (!(fp->f_flag & FREAD)) { 1382 *(int *)data = 0; 1383 PIPE_UNLOCK(mpipe); 1384 return (0); 1385 } 1386 if (mpipe->pipe_state & PIPE_DIRECTW) 1387 *(int *)data = mpipe->pipe_map.cnt; 1388 else 1389 *(int *)data = mpipe->pipe_buffer.cnt; 1390 break; 1391 1392 case FIOSETOWN: 1393 PIPE_UNLOCK(mpipe); 1394 error = fsetown(*(int *)data, &mpipe->pipe_sigio); 1395 goto out_unlocked; 1396 1397 case FIOGETOWN: 1398 *(int *)data = fgetown(&mpipe->pipe_sigio); 1399 break; 1400 1401 /* This is deprecated, FIOSETOWN should be used instead. */ 1402 case TIOCSPGRP: 1403 PIPE_UNLOCK(mpipe); 1404 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio); 1405 goto out_unlocked; 1406 1407 /* This is deprecated, FIOGETOWN should be used instead. */ 1408 case TIOCGPGRP: 1409 *(int *)data = -fgetown(&mpipe->pipe_sigio); 1410 break; 1411 1412 default: 1413 error = ENOTTY; 1414 break; 1415 } 1416 PIPE_UNLOCK(mpipe); 1417 out_unlocked: 1418 return (error); 1419 } 1420 1421 static int 1422 pipe_poll(fp, events, active_cred, td) 1423 struct file *fp; 1424 int events; 1425 struct ucred *active_cred; 1426 struct thread *td; 1427 { 1428 struct pipe *rpipe; 1429 struct pipe *wpipe; 1430 int levents, revents; 1431 #ifdef MAC 1432 int error; 1433 #endif 1434 1435 revents = 0; 1436 rpipe = fp->f_data; 1437 wpipe = PIPE_PEER(rpipe); 1438 PIPE_LOCK(rpipe); 1439 #ifdef MAC 1440 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair); 1441 if (error) 1442 goto locked_error; 1443 #endif 1444 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) 1445 if ((rpipe->pipe_state & PIPE_DIRECTW) || 1446 (rpipe->pipe_buffer.cnt > 0)) 1447 revents |= events & (POLLIN | POLLRDNORM); 1448 1449 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) 1450 if (wpipe->pipe_present != PIPE_ACTIVE || 1451 (wpipe->pipe_state & PIPE_EOF) || 1452 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) && 1453 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF || 1454 wpipe->pipe_buffer.size == 0))) 1455 revents |= events & (POLLOUT | POLLWRNORM); 1456 1457 levents = events & 1458 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND); 1459 if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents && 1460 fp->f_seqcount == rpipe->pipe_wgen) 1461 events |= POLLINIGNEOF; 1462 1463 if ((events & POLLINIGNEOF) == 0) { 1464 if (rpipe->pipe_state & PIPE_EOF) { 1465 revents |= (events & (POLLIN | POLLRDNORM)); 1466 if (wpipe->pipe_present != PIPE_ACTIVE || 1467 (wpipe->pipe_state & PIPE_EOF)) 1468 revents |= POLLHUP; 1469 } 1470 } 1471 1472 if (revents == 0) { 1473 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) { 1474 selrecord(td, &rpipe->pipe_sel); 1475 if (SEL_WAITING(&rpipe->pipe_sel)) 1476 rpipe->pipe_state |= PIPE_SEL; 1477 } 1478 1479 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) { 1480 selrecord(td, &wpipe->pipe_sel); 1481 if (SEL_WAITING(&wpipe->pipe_sel)) 1482 wpipe->pipe_state |= PIPE_SEL; 1483 } 1484 } 1485 #ifdef MAC 1486 locked_error: 1487 #endif 1488 PIPE_UNLOCK(rpipe); 1489 1490 return (revents); 1491 } 1492 1493 /* 1494 * We shouldn't need locks here as we're doing a read and this should 1495 * be a natural race. 1496 */ 1497 static int 1498 pipe_stat(fp, ub, active_cred, td) 1499 struct file *fp; 1500 struct stat *ub; 1501 struct ucred *active_cred; 1502 struct thread *td; 1503 { 1504 struct pipe *pipe; 1505 int new_unr; 1506 #ifdef MAC 1507 int error; 1508 #endif 1509 1510 pipe = fp->f_data; 1511 PIPE_LOCK(pipe); 1512 #ifdef MAC 1513 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair); 1514 if (error) { 1515 PIPE_UNLOCK(pipe); 1516 return (error); 1517 } 1518 #endif 1519 1520 /* For named pipes ask the underlying filesystem. */ 1521 if (pipe->pipe_state & PIPE_NAMED) { 1522 PIPE_UNLOCK(pipe); 1523 return (vnops.fo_stat(fp, ub, active_cred, td)); 1524 } 1525 1526 /* 1527 * Lazily allocate an inode number for the pipe. Most pipe 1528 * users do not call fstat(2) on the pipe, which means that 1529 * postponing the inode allocation until it is must be 1530 * returned to userland is useful. If alloc_unr failed, 1531 * assign st_ino zero instead of returning an error. 1532 * Special pipe_ino values: 1533 * -1 - not yet initialized; 1534 * 0 - alloc_unr failed, return 0 as st_ino forever. 1535 */ 1536 if (pipe->pipe_ino == (ino_t)-1) { 1537 new_unr = alloc_unr(pipeino_unr); 1538 if (new_unr != -1) 1539 pipe->pipe_ino = new_unr; 1540 else 1541 pipe->pipe_ino = 0; 1542 } 1543 PIPE_UNLOCK(pipe); 1544 1545 bzero(ub, sizeof(*ub)); 1546 ub->st_mode = S_IFIFO; 1547 ub->st_blksize = PAGE_SIZE; 1548 if (pipe->pipe_state & PIPE_DIRECTW) 1549 ub->st_size = pipe->pipe_map.cnt; 1550 else 1551 ub->st_size = pipe->pipe_buffer.cnt; 1552 ub->st_blocks = howmany(ub->st_size, ub->st_blksize); 1553 ub->st_atim = pipe->pipe_atime; 1554 ub->st_mtim = pipe->pipe_mtime; 1555 ub->st_ctim = pipe->pipe_ctime; 1556 ub->st_uid = fp->f_cred->cr_uid; 1557 ub->st_gid = fp->f_cred->cr_gid; 1558 ub->st_dev = pipedev_ino; 1559 ub->st_ino = pipe->pipe_ino; 1560 /* 1561 * Left as 0: st_nlink, st_rdev, st_flags, st_gen. 1562 */ 1563 return (0); 1564 } 1565 1566 /* ARGSUSED */ 1567 static int 1568 pipe_close(fp, td) 1569 struct file *fp; 1570 struct thread *td; 1571 { 1572 1573 if (fp->f_vnode != NULL) 1574 return vnops.fo_close(fp, td); 1575 fp->f_ops = &badfileops; 1576 pipe_dtor(fp->f_data); 1577 fp->f_data = NULL; 1578 return (0); 1579 } 1580 1581 static int 1582 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td) 1583 { 1584 struct pipe *cpipe; 1585 int error; 1586 1587 cpipe = fp->f_data; 1588 if (cpipe->pipe_state & PIPE_NAMED) 1589 error = vn_chmod(fp, mode, active_cred, td); 1590 else 1591 error = invfo_chmod(fp, mode, active_cred, td); 1592 return (error); 1593 } 1594 1595 static int 1596 pipe_chown(fp, uid, gid, active_cred, td) 1597 struct file *fp; 1598 uid_t uid; 1599 gid_t gid; 1600 struct ucred *active_cred; 1601 struct thread *td; 1602 { 1603 struct pipe *cpipe; 1604 int error; 1605 1606 cpipe = fp->f_data; 1607 if (cpipe->pipe_state & PIPE_NAMED) 1608 error = vn_chown(fp, uid, gid, active_cred, td); 1609 else 1610 error = invfo_chown(fp, uid, gid, active_cred, td); 1611 return (error); 1612 } 1613 1614 static int 1615 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp) 1616 { 1617 struct pipe *pi; 1618 1619 if (fp->f_type == DTYPE_FIFO) 1620 return (vn_fill_kinfo(fp, kif, fdp)); 1621 kif->kf_type = KF_TYPE_PIPE; 1622 pi = fp->f_data; 1623 kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi; 1624 kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer; 1625 kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt; 1626 return (0); 1627 } 1628 1629 static void 1630 pipe_free_kmem(cpipe) 1631 struct pipe *cpipe; 1632 { 1633 1634 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), 1635 ("pipe_free_kmem: pipe mutex locked")); 1636 1637 if (cpipe->pipe_buffer.buffer != NULL) { 1638 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size); 1639 vm_map_remove(pipe_map, 1640 (vm_offset_t)cpipe->pipe_buffer.buffer, 1641 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size); 1642 cpipe->pipe_buffer.buffer = NULL; 1643 } 1644 #ifndef PIPE_NODIRECT 1645 { 1646 cpipe->pipe_map.cnt = 0; 1647 cpipe->pipe_map.pos = 0; 1648 cpipe->pipe_map.npages = 0; 1649 } 1650 #endif 1651 } 1652 1653 /* 1654 * shutdown the pipe 1655 */ 1656 static void 1657 pipeclose(cpipe) 1658 struct pipe *cpipe; 1659 { 1660 struct pipepair *pp; 1661 struct pipe *ppipe; 1662 1663 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL")); 1664 1665 PIPE_LOCK(cpipe); 1666 pipelock(cpipe, 0); 1667 pp = cpipe->pipe_pair; 1668 1669 pipeselwakeup(cpipe); 1670 1671 /* 1672 * If the other side is blocked, wake it up saying that 1673 * we want to close it down. 1674 */ 1675 cpipe->pipe_state |= PIPE_EOF; 1676 while (cpipe->pipe_busy) { 1677 wakeup(cpipe); 1678 cpipe->pipe_state |= PIPE_WANT; 1679 pipeunlock(cpipe); 1680 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0); 1681 pipelock(cpipe, 0); 1682 } 1683 1684 1685 /* 1686 * Disconnect from peer, if any. 1687 */ 1688 ppipe = cpipe->pipe_peer; 1689 if (ppipe->pipe_present == PIPE_ACTIVE) { 1690 pipeselwakeup(ppipe); 1691 1692 ppipe->pipe_state |= PIPE_EOF; 1693 wakeup(ppipe); 1694 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0); 1695 } 1696 1697 /* 1698 * Mark this endpoint as free. Release kmem resources. We 1699 * don't mark this endpoint as unused until we've finished 1700 * doing that, or the pipe might disappear out from under 1701 * us. 1702 */ 1703 PIPE_UNLOCK(cpipe); 1704 pipe_free_kmem(cpipe); 1705 PIPE_LOCK(cpipe); 1706 cpipe->pipe_present = PIPE_CLOSING; 1707 pipeunlock(cpipe); 1708 1709 /* 1710 * knlist_clear() may sleep dropping the PIPE_MTX. Set the 1711 * PIPE_FINALIZED, that allows other end to free the 1712 * pipe_pair, only after the knotes are completely dismantled. 1713 */ 1714 knlist_clear(&cpipe->pipe_sel.si_note, 1); 1715 cpipe->pipe_present = PIPE_FINALIZED; 1716 seldrain(&cpipe->pipe_sel); 1717 knlist_destroy(&cpipe->pipe_sel.si_note); 1718 1719 /* 1720 * If both endpoints are now closed, release the memory for the 1721 * pipe pair. If not, unlock. 1722 */ 1723 if (ppipe->pipe_present == PIPE_FINALIZED) { 1724 PIPE_UNLOCK(cpipe); 1725 #ifdef MAC 1726 mac_pipe_destroy(pp); 1727 #endif 1728 uma_zfree(pipe_zone, cpipe->pipe_pair); 1729 } else 1730 PIPE_UNLOCK(cpipe); 1731 } 1732 1733 /*ARGSUSED*/ 1734 static int 1735 pipe_kqfilter(struct file *fp, struct knote *kn) 1736 { 1737 struct pipe *cpipe; 1738 1739 /* 1740 * If a filter is requested that is not supported by this file 1741 * descriptor, don't return an error, but also don't ever generate an 1742 * event. 1743 */ 1744 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) { 1745 kn->kn_fop = &pipe_nfiltops; 1746 return (0); 1747 } 1748 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) { 1749 kn->kn_fop = &pipe_nfiltops; 1750 return (0); 1751 } 1752 cpipe = fp->f_data; 1753 PIPE_LOCK(cpipe); 1754 switch (kn->kn_filter) { 1755 case EVFILT_READ: 1756 kn->kn_fop = &pipe_rfiltops; 1757 break; 1758 case EVFILT_WRITE: 1759 kn->kn_fop = &pipe_wfiltops; 1760 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) { 1761 /* other end of pipe has been closed */ 1762 PIPE_UNLOCK(cpipe); 1763 return (EPIPE); 1764 } 1765 cpipe = PIPE_PEER(cpipe); 1766 break; 1767 default: 1768 PIPE_UNLOCK(cpipe); 1769 return (EINVAL); 1770 } 1771 1772 kn->kn_hook = cpipe; 1773 knlist_add(&cpipe->pipe_sel.si_note, kn, 1); 1774 PIPE_UNLOCK(cpipe); 1775 return (0); 1776 } 1777 1778 static void 1779 filt_pipedetach(struct knote *kn) 1780 { 1781 struct pipe *cpipe = kn->kn_hook; 1782 1783 PIPE_LOCK(cpipe); 1784 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1); 1785 PIPE_UNLOCK(cpipe); 1786 } 1787 1788 /*ARGSUSED*/ 1789 static int 1790 filt_piperead(struct knote *kn, long hint) 1791 { 1792 struct pipe *rpipe = kn->kn_hook; 1793 struct pipe *wpipe = rpipe->pipe_peer; 1794 int ret; 1795 1796 PIPE_LOCK_ASSERT(rpipe, MA_OWNED); 1797 kn->kn_data = rpipe->pipe_buffer.cnt; 1798 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) 1799 kn->kn_data = rpipe->pipe_map.cnt; 1800 1801 if ((rpipe->pipe_state & PIPE_EOF) || 1802 wpipe->pipe_present != PIPE_ACTIVE || 1803 (wpipe->pipe_state & PIPE_EOF)) { 1804 kn->kn_flags |= EV_EOF; 1805 return (1); 1806 } 1807 ret = kn->kn_data > 0; 1808 return ret; 1809 } 1810 1811 /*ARGSUSED*/ 1812 static int 1813 filt_pipewrite(struct knote *kn, long hint) 1814 { 1815 struct pipe *wpipe; 1816 1817 /* 1818 * If this end of the pipe is closed, the knote was removed from the 1819 * knlist and the list lock (i.e., the pipe lock) is therefore not held. 1820 */ 1821 wpipe = kn->kn_hook; 1822 if (wpipe->pipe_present != PIPE_ACTIVE || 1823 (wpipe->pipe_state & PIPE_EOF)) { 1824 kn->kn_data = 0; 1825 kn->kn_flags |= EV_EOF; 1826 return (1); 1827 } 1828 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 1829 kn->kn_data = (wpipe->pipe_buffer.size > 0) ? 1830 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF; 1831 if (wpipe->pipe_state & PIPE_DIRECTW) 1832 kn->kn_data = 0; 1833 1834 return (kn->kn_data >= PIPE_BUF); 1835 } 1836 1837 static void 1838 filt_pipedetach_notsup(struct knote *kn) 1839 { 1840 1841 } 1842 1843 static int 1844 filt_pipenotsup(struct knote *kn, long hint) 1845 { 1846 1847 return (0); 1848 }
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