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 <sys/cdefs.h> 93 __FBSDID("$FreeBSD$"); 94 95 #include <sys/param.h> 96 #include <sys/systm.h> 97 #include <sys/conf.h> 98 #include <sys/fcntl.h> 99 #include <sys/file.h> 100 #include <sys/filedesc.h> 101 #include <sys/filio.h> 102 #include <sys/kernel.h> 103 #include <sys/lock.h> 104 #include <sys/mutex.h> 105 #include <sys/ttycom.h> 106 #include <sys/stat.h> 107 #include <sys/malloc.h> 108 #include <sys/poll.h> 109 #include <sys/selinfo.h> 110 #include <sys/signalvar.h> 111 #include <sys/syscallsubr.h> 112 #include <sys/sysctl.h> 113 #include <sys/sysproto.h> 114 #include <sys/pipe.h> 115 #include <sys/proc.h> 116 #include <sys/vnode.h> 117 #include <sys/uio.h> 118 #include <sys/user.h> 119 #include <sys/event.h> 120 121 #include <security/mac/mac_framework.h> 122 123 #include <vm/vm.h> 124 #include <vm/vm_param.h> 125 #include <vm/vm_object.h> 126 #include <vm/vm_kern.h> 127 #include <vm/vm_extern.h> 128 #include <vm/pmap.h> 129 #include <vm/vm_map.h> 130 #include <vm/vm_page.h> 131 #include <vm/uma.h> 132 133 /* 134 * Use this define if you want to disable *fancy* VM things. Expect an 135 * approx 30% decrease in transfer rate. This could be useful for 136 * NetBSD or OpenBSD. 137 */ 138 /* #define PIPE_NODIRECT */ 139 140 #define PIPE_PEER(pipe) \ 141 (((pipe)->pipe_state & PIPE_NAMED) ? (pipe) : ((pipe)->pipe_peer)) 142 143 /* 144 * interfaces to the outside world 145 */ 146 static fo_rdwr_t pipe_read; 147 static fo_rdwr_t pipe_write; 148 static fo_truncate_t pipe_truncate; 149 static fo_ioctl_t pipe_ioctl; 150 static fo_poll_t pipe_poll; 151 static fo_kqfilter_t pipe_kqfilter; 152 static fo_stat_t pipe_stat; 153 static fo_close_t pipe_close; 154 static fo_chmod_t pipe_chmod; 155 static fo_chown_t pipe_chown; 156 static fo_fill_kinfo_t pipe_fill_kinfo; 157 158 struct fileops pipeops = { 159 .fo_read = pipe_read, 160 .fo_write = pipe_write, 161 .fo_truncate = pipe_truncate, 162 .fo_ioctl = pipe_ioctl, 163 .fo_poll = pipe_poll, 164 .fo_kqfilter = pipe_kqfilter, 165 .fo_stat = pipe_stat, 166 .fo_close = pipe_close, 167 .fo_chmod = pipe_chmod, 168 .fo_chown = pipe_chown, 169 .fo_sendfile = invfo_sendfile, 170 .fo_fill_kinfo = pipe_fill_kinfo, 171 .fo_flags = DFLAG_PASSABLE 172 }; 173 174 static void filt_pipedetach(struct knote *kn); 175 static void filt_pipedetach_notsup(struct knote *kn); 176 static int filt_pipenotsup(struct knote *kn, long hint); 177 static int filt_piperead(struct knote *kn, long hint); 178 static int filt_pipewrite(struct knote *kn, long hint); 179 180 static struct filterops pipe_nfiltops = { 181 .f_isfd = 1, 182 .f_detach = filt_pipedetach_notsup, 183 .f_event = filt_pipenotsup 184 }; 185 static struct filterops pipe_rfiltops = { 186 .f_isfd = 1, 187 .f_detach = filt_pipedetach, 188 .f_event = filt_piperead 189 }; 190 static struct filterops pipe_wfiltops = { 191 .f_isfd = 1, 192 .f_detach = filt_pipedetach, 193 .f_event = filt_pipewrite 194 }; 195 196 /* 197 * Default pipe buffer size(s), this can be kind-of large now because pipe 198 * space is pageable. The pipe code will try to maintain locality of 199 * reference for performance reasons, so small amounts of outstanding I/O 200 * will not wipe the cache. 201 */ 202 #define MINPIPESIZE (PIPE_SIZE/3) 203 #define MAXPIPESIZE (2*PIPE_SIZE/3) 204 205 static long amountpipekva; 206 static int pipefragretry; 207 static int pipeallocfail; 208 static int piperesizefail; 209 static int piperesizeallowed = 1; 210 211 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, 212 &maxpipekva, 0, "Pipe KVA limit"); 213 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD, 214 &amountpipekva, 0, "Pipe KVA usage"); 215 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD, 216 &pipefragretry, 0, "Pipe allocation retries due to fragmentation"); 217 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD, 218 &pipeallocfail, 0, "Pipe allocation failures"); 219 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD, 220 &piperesizefail, 0, "Pipe resize failures"); 221 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW, 222 &piperesizeallowed, 0, "Pipe resizing allowed"); 223 224 static void pipeinit(void *dummy __unused); 225 static void pipeclose(struct pipe *cpipe); 226 static void pipe_free_kmem(struct pipe *cpipe); 227 static void pipe_create(struct pipe *pipe, int backing); 228 static void pipe_paircreate(struct thread *td, struct pipepair **p_pp); 229 static __inline int pipelock(struct pipe *cpipe, int catch); 230 static __inline void pipeunlock(struct pipe *cpipe); 231 #ifndef PIPE_NODIRECT 232 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio); 233 static void pipe_destroy_write_buffer(struct pipe *wpipe); 234 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio); 235 static void pipe_clone_write_buffer(struct pipe *wpipe); 236 #endif 237 static int pipespace(struct pipe *cpipe, int size); 238 static int pipespace_new(struct pipe *cpipe, int size); 239 240 static int pipe_zone_ctor(void *mem, int size, void *arg, int flags); 241 static int pipe_zone_init(void *mem, int size, int flags); 242 static void pipe_zone_fini(void *mem, int size); 243 244 static uma_zone_t pipe_zone; 245 static struct unrhdr *pipeino_unr; 246 static dev_t pipedev_ino; 247 248 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL); 249 250 static void 251 pipeinit(void *dummy __unused) 252 { 253 254 pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair), 255 pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini, 256 UMA_ALIGN_PTR, 0); 257 KASSERT(pipe_zone != NULL, ("pipe_zone not initialized")); 258 pipeino_unr = new_unrhdr(1, INT32_MAX, NULL); 259 KASSERT(pipeino_unr != NULL, ("pipe fake inodes not initialized")); 260 pipedev_ino = devfs_alloc_cdp_inode(); 261 KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized")); 262 } 263 264 static int 265 pipe_zone_ctor(void *mem, int size, void *arg, int flags) 266 { 267 struct pipepair *pp; 268 struct pipe *rpipe, *wpipe; 269 270 KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size")); 271 272 pp = (struct pipepair *)mem; 273 274 /* 275 * We zero both pipe endpoints to make sure all the kmem pointers 276 * are NULL, flag fields are zero'd, etc. We timestamp both 277 * endpoints with the same time. 278 */ 279 rpipe = &pp->pp_rpipe; 280 bzero(rpipe, sizeof(*rpipe)); 281 vfs_timestamp(&rpipe->pipe_ctime); 282 rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime; 283 284 wpipe = &pp->pp_wpipe; 285 bzero(wpipe, sizeof(*wpipe)); 286 wpipe->pipe_ctime = rpipe->pipe_ctime; 287 wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime; 288 289 rpipe->pipe_peer = wpipe; 290 rpipe->pipe_pair = pp; 291 wpipe->pipe_peer = rpipe; 292 wpipe->pipe_pair = pp; 293 294 /* 295 * Mark both endpoints as present; they will later get free'd 296 * one at a time. When both are free'd, then the whole pair 297 * is released. 298 */ 299 rpipe->pipe_present = PIPE_ACTIVE; 300 wpipe->pipe_present = PIPE_ACTIVE; 301 302 /* 303 * Eventually, the MAC Framework may initialize the label 304 * in ctor or init, but for now we do it elswhere to avoid 305 * blocking in ctor or init. 306 */ 307 pp->pp_label = NULL; 308 309 return (0); 310 } 311 312 static int 313 pipe_zone_init(void *mem, int size, int flags) 314 { 315 struct pipepair *pp; 316 317 KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size")); 318 319 pp = (struct pipepair *)mem; 320 321 mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_NEW); 322 return (0); 323 } 324 325 static void 326 pipe_zone_fini(void *mem, int size) 327 { 328 struct pipepair *pp; 329 330 KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size")); 331 332 pp = (struct pipepair *)mem; 333 334 mtx_destroy(&pp->pp_mtx); 335 } 336 337 static void 338 pipe_paircreate(struct thread *td, struct pipepair **p_pp) 339 { 340 struct pipepair *pp; 341 struct pipe *rpipe, *wpipe; 342 343 *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK); 344 #ifdef MAC 345 /* 346 * The MAC label is shared between the connected endpoints. As a 347 * result mac_pipe_init() and mac_pipe_create() are called once 348 * for the pair, and not on the endpoints. 349 */ 350 mac_pipe_init(pp); 351 mac_pipe_create(td->td_ucred, pp); 352 #endif 353 rpipe = &pp->pp_rpipe; 354 wpipe = &pp->pp_wpipe; 355 356 knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe)); 357 knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe)); 358 359 /* Only the forward direction pipe is backed by default */ 360 pipe_create(rpipe, 1); 361 pipe_create(wpipe, 0); 362 363 rpipe->pipe_state |= PIPE_DIRECTOK; 364 wpipe->pipe_state |= PIPE_DIRECTOK; 365 } 366 367 void 368 pipe_named_ctor(struct pipe **ppipe, struct thread *td) 369 { 370 struct pipepair *pp; 371 372 pipe_paircreate(td, &pp); 373 pp->pp_rpipe.pipe_state |= PIPE_NAMED; 374 *ppipe = &pp->pp_rpipe; 375 } 376 377 void 378 pipe_dtor(struct pipe *dpipe) 379 { 380 struct pipe *peer; 381 ino_t ino; 382 383 ino = dpipe->pipe_ino; 384 peer = (dpipe->pipe_state & PIPE_NAMED) != 0 ? dpipe->pipe_peer : NULL; 385 funsetown(&dpipe->pipe_sigio); 386 pipeclose(dpipe); 387 if (peer != NULL) { 388 funsetown(&peer->pipe_sigio); 389 pipeclose(peer); 390 } 391 if (ino != 0 && ino != (ino_t)-1) 392 free_unr(pipeino_unr, ino); 393 } 394 395 /* 396 * The pipe system call for the DTYPE_PIPE type of pipes. If we fail, let 397 * the zone pick up the pieces via pipeclose(). 398 */ 399 int 400 kern_pipe(struct thread *td, int fildes[2], int flags, struct filecaps *fcaps1, 401 struct filecaps *fcaps2) 402 { 403 struct file *rf, *wf; 404 struct pipe *rpipe, *wpipe; 405 struct pipepair *pp; 406 int fd, fflags, error; 407 408 pipe_paircreate(td, &pp); 409 rpipe = &pp->pp_rpipe; 410 wpipe = &pp->pp_wpipe; 411 error = falloc_caps(td, &rf, &fd, flags, fcaps1); 412 if (error) { 413 pipeclose(rpipe); 414 pipeclose(wpipe); 415 return (error); 416 } 417 /* An extra reference on `rf' has been held for us by falloc_caps(). */ 418 fildes[0] = fd; 419 420 fflags = FREAD | FWRITE; 421 if ((flags & O_NONBLOCK) != 0) 422 fflags |= FNONBLOCK; 423 424 /* 425 * Warning: once we've gotten past allocation of the fd for the 426 * read-side, we can only drop the read side via fdrop() in order 427 * to avoid races against processes which manage to dup() the read 428 * side while we are blocked trying to allocate the write side. 429 */ 430 finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops); 431 error = falloc_caps(td, &wf, &fd, flags, fcaps2); 432 if (error) { 433 fdclose(td, rf, fildes[0]); 434 fdrop(rf, td); 435 /* rpipe has been closed by fdrop(). */ 436 pipeclose(wpipe); 437 return (error); 438 } 439 /* An extra reference on `wf' has been held for us by falloc_caps(). */ 440 finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops); 441 fdrop(wf, td); 442 fildes[1] = fd; 443 fdrop(rf, td); 444 445 return (0); 446 } 447 448 /* ARGSUSED */ 449 int 450 sys_pipe(struct thread *td, struct pipe_args *uap) 451 { 452 int error; 453 int fildes[2]; 454 455 error = kern_pipe(td, fildes, 0, NULL, NULL); 456 if (error) 457 return (error); 458 459 td->td_retval[0] = fildes[0]; 460 td->td_retval[1] = fildes[1]; 461 462 return (0); 463 } 464 465 int 466 sys_pipe2(struct thread *td, struct pipe2_args *uap) 467 { 468 int error, fildes[2]; 469 470 if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK)) 471 return (EINVAL); 472 error = kern_pipe(td, fildes, uap->flags, NULL, NULL); 473 if (error) 474 return (error); 475 error = copyout(fildes, uap->fildes, 2 * sizeof(int)); 476 if (error) { 477 (void)kern_close(td, fildes[0]); 478 (void)kern_close(td, fildes[1]); 479 } 480 return (error); 481 } 482 483 /* 484 * Allocate kva for pipe circular buffer, the space is pageable 485 * This routine will 'realloc' the size of a pipe safely, if it fails 486 * it will retain the old buffer. 487 * If it fails it will return ENOMEM. 488 */ 489 static int 490 pipespace_new(cpipe, size) 491 struct pipe *cpipe; 492 int size; 493 { 494 caddr_t buffer; 495 int error, cnt, firstseg; 496 static int curfail = 0; 497 static struct timeval lastfail; 498 499 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked")); 500 KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW), 501 ("pipespace: resize of direct writes not allowed")); 502 retry: 503 cnt = cpipe->pipe_buffer.cnt; 504 if (cnt > size) 505 size = cnt; 506 507 size = round_page(size); 508 buffer = (caddr_t) vm_map_min(pipe_map); 509 510 error = vm_map_find(pipe_map, NULL, 0, 511 (vm_offset_t *) &buffer, size, 0, VMFS_ANY_SPACE, 512 VM_PROT_ALL, VM_PROT_ALL, 0); 513 if (error != KERN_SUCCESS) { 514 if ((cpipe->pipe_buffer.buffer == NULL) && 515 (size > SMALL_PIPE_SIZE)) { 516 size = SMALL_PIPE_SIZE; 517 pipefragretry++; 518 goto retry; 519 } 520 if (cpipe->pipe_buffer.buffer == NULL) { 521 pipeallocfail++; 522 if (ppsratecheck(&lastfail, &curfail, 1)) 523 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n"); 524 } else { 525 piperesizefail++; 526 } 527 return (ENOMEM); 528 } 529 530 /* copy data, then free old resources if we're resizing */ 531 if (cnt > 0) { 532 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) { 533 firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out; 534 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 535 buffer, firstseg); 536 if ((cnt - firstseg) > 0) 537 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg], 538 cpipe->pipe_buffer.in); 539 } else { 540 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 541 buffer, cnt); 542 } 543 } 544 pipe_free_kmem(cpipe); 545 cpipe->pipe_buffer.buffer = buffer; 546 cpipe->pipe_buffer.size = size; 547 cpipe->pipe_buffer.in = cnt; 548 cpipe->pipe_buffer.out = 0; 549 cpipe->pipe_buffer.cnt = cnt; 550 atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size); 551 return (0); 552 } 553 554 /* 555 * Wrapper for pipespace_new() that performs locking assertions. 556 */ 557 static int 558 pipespace(cpipe, size) 559 struct pipe *cpipe; 560 int size; 561 { 562 563 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 564 ("Unlocked pipe passed to pipespace")); 565 return (pipespace_new(cpipe, size)); 566 } 567 568 /* 569 * lock a pipe for I/O, blocking other access 570 */ 571 static __inline int 572 pipelock(cpipe, catch) 573 struct pipe *cpipe; 574 int catch; 575 { 576 int error; 577 578 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 579 while (cpipe->pipe_state & PIPE_LOCKFL) { 580 cpipe->pipe_state |= PIPE_LWANT; 581 error = msleep(cpipe, PIPE_MTX(cpipe), 582 catch ? (PRIBIO | PCATCH) : PRIBIO, 583 "pipelk", 0); 584 if (error != 0) 585 return (error); 586 } 587 cpipe->pipe_state |= PIPE_LOCKFL; 588 return (0); 589 } 590 591 /* 592 * unlock a pipe I/O lock 593 */ 594 static __inline void 595 pipeunlock(cpipe) 596 struct pipe *cpipe; 597 { 598 599 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 600 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 601 ("Unlocked pipe passed to pipeunlock")); 602 cpipe->pipe_state &= ~PIPE_LOCKFL; 603 if (cpipe->pipe_state & PIPE_LWANT) { 604 cpipe->pipe_state &= ~PIPE_LWANT; 605 wakeup(cpipe); 606 } 607 } 608 609 void 610 pipeselwakeup(cpipe) 611 struct pipe *cpipe; 612 { 613 614 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 615 if (cpipe->pipe_state & PIPE_SEL) { 616 selwakeuppri(&cpipe->pipe_sel, PSOCK); 617 if (!SEL_WAITING(&cpipe->pipe_sel)) 618 cpipe->pipe_state &= ~PIPE_SEL; 619 } 620 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) 621 pgsigio(&cpipe->pipe_sigio, SIGIO, 0); 622 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0); 623 } 624 625 /* 626 * Initialize and allocate VM and memory for pipe. The structure 627 * will start out zero'd from the ctor, so we just manage the kmem. 628 */ 629 static void 630 pipe_create(pipe, backing) 631 struct pipe *pipe; 632 int backing; 633 { 634 635 if (backing) { 636 /* 637 * Note that these functions can fail if pipe map is exhausted 638 * (as a result of too many pipes created), but we ignore the 639 * error as it is not fatal and could be provoked by 640 * unprivileged users. The only consequence is worse performance 641 * with given pipe. 642 */ 643 if (amountpipekva > maxpipekva / 2) 644 (void)pipespace_new(pipe, SMALL_PIPE_SIZE); 645 else 646 (void)pipespace_new(pipe, PIPE_SIZE); 647 } 648 649 pipe->pipe_ino = -1; 650 } 651 652 /* ARGSUSED */ 653 static int 654 pipe_read(fp, uio, active_cred, flags, td) 655 struct file *fp; 656 struct uio *uio; 657 struct ucred *active_cred; 658 struct thread *td; 659 int flags; 660 { 661 struct pipe *rpipe; 662 int error; 663 int nread = 0; 664 int size; 665 666 rpipe = fp->f_data; 667 PIPE_LOCK(rpipe); 668 ++rpipe->pipe_busy; 669 error = pipelock(rpipe, 1); 670 if (error) 671 goto unlocked_error; 672 673 #ifdef MAC 674 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair); 675 if (error) 676 goto locked_error; 677 #endif 678 if (amountpipekva > (3 * maxpipekva) / 4) { 679 if (!(rpipe->pipe_state & PIPE_DIRECTW) && 680 (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) && 681 (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) && 682 (piperesizeallowed == 1)) { 683 PIPE_UNLOCK(rpipe); 684 pipespace(rpipe, SMALL_PIPE_SIZE); 685 PIPE_LOCK(rpipe); 686 } 687 } 688 689 while (uio->uio_resid) { 690 /* 691 * normal pipe buffer receive 692 */ 693 if (rpipe->pipe_buffer.cnt > 0) { 694 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 695 if (size > rpipe->pipe_buffer.cnt) 696 size = rpipe->pipe_buffer.cnt; 697 if (size > uio->uio_resid) 698 size = uio->uio_resid; 699 700 PIPE_UNLOCK(rpipe); 701 error = uiomove( 702 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 703 size, uio); 704 PIPE_LOCK(rpipe); 705 if (error) 706 break; 707 708 rpipe->pipe_buffer.out += size; 709 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 710 rpipe->pipe_buffer.out = 0; 711 712 rpipe->pipe_buffer.cnt -= size; 713 714 /* 715 * If there is no more to read in the pipe, reset 716 * its pointers to the beginning. This improves 717 * cache hit stats. 718 */ 719 if (rpipe->pipe_buffer.cnt == 0) { 720 rpipe->pipe_buffer.in = 0; 721 rpipe->pipe_buffer.out = 0; 722 } 723 nread += size; 724 #ifndef PIPE_NODIRECT 725 /* 726 * Direct copy, bypassing a kernel buffer. 727 */ 728 } else if ((size = rpipe->pipe_map.cnt) && 729 (rpipe->pipe_state & PIPE_DIRECTW)) { 730 if (size > uio->uio_resid) 731 size = (u_int) uio->uio_resid; 732 733 PIPE_UNLOCK(rpipe); 734 error = uiomove_fromphys(rpipe->pipe_map.ms, 735 rpipe->pipe_map.pos, size, uio); 736 PIPE_LOCK(rpipe); 737 if (error) 738 break; 739 nread += size; 740 rpipe->pipe_map.pos += size; 741 rpipe->pipe_map.cnt -= size; 742 if (rpipe->pipe_map.cnt == 0) { 743 rpipe->pipe_state &= ~(PIPE_DIRECTW|PIPE_WANTW); 744 wakeup(rpipe); 745 } 746 #endif 747 } else { 748 /* 749 * detect EOF condition 750 * read returns 0 on EOF, no need to set error 751 */ 752 if (rpipe->pipe_state & PIPE_EOF) 753 break; 754 755 /* 756 * If the "write-side" has been blocked, wake it up now. 757 */ 758 if (rpipe->pipe_state & PIPE_WANTW) { 759 rpipe->pipe_state &= ~PIPE_WANTW; 760 wakeup(rpipe); 761 } 762 763 /* 764 * Break if some data was read. 765 */ 766 if (nread > 0) 767 break; 768 769 /* 770 * Unlock the pipe buffer for our remaining processing. 771 * We will either break out with an error or we will 772 * sleep and relock to loop. 773 */ 774 pipeunlock(rpipe); 775 776 /* 777 * Handle non-blocking mode operation or 778 * wait for more data. 779 */ 780 if (fp->f_flag & FNONBLOCK) { 781 error = EAGAIN; 782 } else { 783 rpipe->pipe_state |= PIPE_WANTR; 784 if ((error = msleep(rpipe, PIPE_MTX(rpipe), 785 PRIBIO | PCATCH, 786 "piperd", 0)) == 0) 787 error = pipelock(rpipe, 1); 788 } 789 if (error) 790 goto unlocked_error; 791 } 792 } 793 #ifdef MAC 794 locked_error: 795 #endif 796 pipeunlock(rpipe); 797 798 /* XXX: should probably do this before getting any locks. */ 799 if (error == 0) 800 vfs_timestamp(&rpipe->pipe_atime); 801 unlocked_error: 802 --rpipe->pipe_busy; 803 804 /* 805 * PIPE_WANT processing only makes sense if pipe_busy is 0. 806 */ 807 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 808 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 809 wakeup(rpipe); 810 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 811 /* 812 * Handle write blocking hysteresis. 813 */ 814 if (rpipe->pipe_state & PIPE_WANTW) { 815 rpipe->pipe_state &= ~PIPE_WANTW; 816 wakeup(rpipe); 817 } 818 } 819 820 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF) 821 pipeselwakeup(rpipe); 822 823 PIPE_UNLOCK(rpipe); 824 return (error); 825 } 826 827 #ifndef PIPE_NODIRECT 828 /* 829 * Map the sending processes' buffer into kernel space and wire it. 830 * This is similar to a physical write operation. 831 */ 832 static int 833 pipe_build_write_buffer(wpipe, uio) 834 struct pipe *wpipe; 835 struct uio *uio; 836 { 837 u_int size; 838 int i; 839 840 PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED); 841 KASSERT(wpipe->pipe_state & PIPE_DIRECTW, 842 ("Clone attempt on non-direct write pipe!")); 843 844 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size) 845 size = wpipe->pipe_buffer.size; 846 else 847 size = uio->uio_iov->iov_len; 848 849 if ((i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 850 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ, 851 wpipe->pipe_map.ms, PIPENPAGES)) < 0) 852 return (EFAULT); 853 854 /* 855 * set up the control block 856 */ 857 wpipe->pipe_map.npages = i; 858 wpipe->pipe_map.pos = 859 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 860 wpipe->pipe_map.cnt = size; 861 862 /* 863 * and update the uio data 864 */ 865 866 uio->uio_iov->iov_len -= size; 867 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size; 868 if (uio->uio_iov->iov_len == 0) 869 uio->uio_iov++; 870 uio->uio_resid -= size; 871 uio->uio_offset += size; 872 return (0); 873 } 874 875 /* 876 * unmap and unwire the process buffer 877 */ 878 static void 879 pipe_destroy_write_buffer(wpipe) 880 struct pipe *wpipe; 881 { 882 883 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 884 vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages); 885 wpipe->pipe_map.npages = 0; 886 } 887 888 /* 889 * In the case of a signal, the writing process might go away. This 890 * code copies the data into the circular buffer so that the source 891 * pages can be freed without loss of data. 892 */ 893 static void 894 pipe_clone_write_buffer(wpipe) 895 struct pipe *wpipe; 896 { 897 struct uio uio; 898 struct iovec iov; 899 int size; 900 int pos; 901 902 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 903 size = wpipe->pipe_map.cnt; 904 pos = wpipe->pipe_map.pos; 905 906 wpipe->pipe_buffer.in = size; 907 wpipe->pipe_buffer.out = 0; 908 wpipe->pipe_buffer.cnt = size; 909 wpipe->pipe_state &= ~PIPE_DIRECTW; 910 911 PIPE_UNLOCK(wpipe); 912 iov.iov_base = wpipe->pipe_buffer.buffer; 913 iov.iov_len = size; 914 uio.uio_iov = &iov; 915 uio.uio_iovcnt = 1; 916 uio.uio_offset = 0; 917 uio.uio_resid = size; 918 uio.uio_segflg = UIO_SYSSPACE; 919 uio.uio_rw = UIO_READ; 920 uio.uio_td = curthread; 921 uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio); 922 PIPE_LOCK(wpipe); 923 pipe_destroy_write_buffer(wpipe); 924 } 925 926 /* 927 * This implements the pipe buffer write mechanism. Note that only 928 * a direct write OR a normal pipe write can be pending at any given time. 929 * If there are any characters in the pipe buffer, the direct write will 930 * be deferred until the receiving process grabs all of the bytes from 931 * the pipe buffer. Then the direct mapping write is set-up. 932 */ 933 static int 934 pipe_direct_write(wpipe, uio) 935 struct pipe *wpipe; 936 struct uio *uio; 937 { 938 int error; 939 940 retry: 941 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 942 error = pipelock(wpipe, 1); 943 if (error != 0) 944 goto error1; 945 if ((wpipe->pipe_state & PIPE_EOF) != 0) { 946 error = EPIPE; 947 pipeunlock(wpipe); 948 goto error1; 949 } 950 while (wpipe->pipe_state & PIPE_DIRECTW) { 951 if (wpipe->pipe_state & PIPE_WANTR) { 952 wpipe->pipe_state &= ~PIPE_WANTR; 953 wakeup(wpipe); 954 } 955 pipeselwakeup(wpipe); 956 wpipe->pipe_state |= PIPE_WANTW; 957 pipeunlock(wpipe); 958 error = msleep(wpipe, PIPE_MTX(wpipe), 959 PRIBIO | PCATCH, "pipdww", 0); 960 if (error) 961 goto error1; 962 else 963 goto retry; 964 } 965 wpipe->pipe_map.cnt = 0; /* transfer not ready yet */ 966 if (wpipe->pipe_buffer.cnt > 0) { 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, "pipdwc", 0); 976 if (error) 977 goto error1; 978 else 979 goto retry; 980 } 981 982 wpipe->pipe_state |= PIPE_DIRECTW; 983 984 PIPE_UNLOCK(wpipe); 985 error = pipe_build_write_buffer(wpipe, uio); 986 PIPE_LOCK(wpipe); 987 if (error) { 988 wpipe->pipe_state &= ~PIPE_DIRECTW; 989 pipeunlock(wpipe); 990 goto error1; 991 } 992 993 error = 0; 994 while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) { 995 if (wpipe->pipe_state & PIPE_EOF) { 996 pipe_destroy_write_buffer(wpipe); 997 pipeselwakeup(wpipe); 998 pipeunlock(wpipe); 999 error = EPIPE; 1000 goto error1; 1001 } 1002 if (wpipe->pipe_state & PIPE_WANTR) { 1003 wpipe->pipe_state &= ~PIPE_WANTR; 1004 wakeup(wpipe); 1005 } 1006 pipeselwakeup(wpipe); 1007 wpipe->pipe_state |= PIPE_WANTW; 1008 pipeunlock(wpipe); 1009 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH, 1010 "pipdwt", 0); 1011 pipelock(wpipe, 0); 1012 } 1013 1014 if (wpipe->pipe_state & PIPE_EOF) 1015 error = EPIPE; 1016 if (wpipe->pipe_state & PIPE_DIRECTW) { 1017 /* 1018 * this bit of trickery substitutes a kernel buffer for 1019 * the process that might be going away. 1020 */ 1021 pipe_clone_write_buffer(wpipe); 1022 } else { 1023 pipe_destroy_write_buffer(wpipe); 1024 } 1025 pipeunlock(wpipe); 1026 return (error); 1027 1028 error1: 1029 wakeup(wpipe); 1030 return (error); 1031 } 1032 #endif 1033 1034 static int 1035 pipe_write(fp, uio, active_cred, flags, td) 1036 struct file *fp; 1037 struct uio *uio; 1038 struct ucred *active_cred; 1039 struct thread *td; 1040 int flags; 1041 { 1042 int error = 0; 1043 int desiredsize; 1044 ssize_t orig_resid; 1045 struct pipe *wpipe, *rpipe; 1046 1047 rpipe = fp->f_data; 1048 wpipe = PIPE_PEER(rpipe); 1049 PIPE_LOCK(rpipe); 1050 error = pipelock(wpipe, 1); 1051 if (error) { 1052 PIPE_UNLOCK(rpipe); 1053 return (error); 1054 } 1055 /* 1056 * detect loss of pipe read side, issue SIGPIPE if lost. 1057 */ 1058 if (wpipe->pipe_present != PIPE_ACTIVE || 1059 (wpipe->pipe_state & PIPE_EOF)) { 1060 pipeunlock(wpipe); 1061 PIPE_UNLOCK(rpipe); 1062 return (EPIPE); 1063 } 1064 #ifdef MAC 1065 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair); 1066 if (error) { 1067 pipeunlock(wpipe); 1068 PIPE_UNLOCK(rpipe); 1069 return (error); 1070 } 1071 #endif 1072 ++wpipe->pipe_busy; 1073 1074 /* Choose a larger size if it's advantageous */ 1075 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size); 1076 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) { 1077 if (piperesizeallowed != 1) 1078 break; 1079 if (amountpipekva > maxpipekva / 2) 1080 break; 1081 if (desiredsize == BIG_PIPE_SIZE) 1082 break; 1083 desiredsize = desiredsize * 2; 1084 } 1085 1086 /* Choose a smaller size if we're in a OOM situation */ 1087 if ((amountpipekva > (3 * maxpipekva) / 4) && 1088 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) && 1089 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) && 1090 (piperesizeallowed == 1)) 1091 desiredsize = SMALL_PIPE_SIZE; 1092 1093 /* Resize if the above determined that a new size was necessary */ 1094 if ((desiredsize != wpipe->pipe_buffer.size) && 1095 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) { 1096 PIPE_UNLOCK(wpipe); 1097 pipespace(wpipe, desiredsize); 1098 PIPE_LOCK(wpipe); 1099 } 1100 if (wpipe->pipe_buffer.size == 0) { 1101 /* 1102 * This can only happen for reverse direction use of pipes 1103 * in a complete OOM situation. 1104 */ 1105 error = ENOMEM; 1106 --wpipe->pipe_busy; 1107 pipeunlock(wpipe); 1108 PIPE_UNLOCK(wpipe); 1109 return (error); 1110 } 1111 1112 pipeunlock(wpipe); 1113 1114 orig_resid = uio->uio_resid; 1115 1116 while (uio->uio_resid) { 1117 int space; 1118 1119 pipelock(wpipe, 0); 1120 if (wpipe->pipe_state & PIPE_EOF) { 1121 pipeunlock(wpipe); 1122 error = EPIPE; 1123 break; 1124 } 1125 #ifndef PIPE_NODIRECT 1126 /* 1127 * If the transfer is large, we can gain performance if 1128 * we do process-to-process copies directly. 1129 * If the write is non-blocking, we don't use the 1130 * direct write mechanism. 1131 * 1132 * The direct write mechanism will detect the reader going 1133 * away on us. 1134 */ 1135 if (uio->uio_segflg == UIO_USERSPACE && 1136 uio->uio_iov->iov_len >= PIPE_MINDIRECT && 1137 wpipe->pipe_buffer.size >= PIPE_MINDIRECT && 1138 (fp->f_flag & FNONBLOCK) == 0) { 1139 pipeunlock(wpipe); 1140 error = pipe_direct_write(wpipe, uio); 1141 if (error) 1142 break; 1143 continue; 1144 } 1145 #endif 1146 1147 /* 1148 * Pipe buffered writes cannot be coincidental with 1149 * direct writes. We wait until the currently executing 1150 * direct write is completed before we start filling the 1151 * pipe buffer. We break out if a signal occurs or the 1152 * reader goes away. 1153 */ 1154 if (wpipe->pipe_state & PIPE_DIRECTW) { 1155 if (wpipe->pipe_state & PIPE_WANTR) { 1156 wpipe->pipe_state &= ~PIPE_WANTR; 1157 wakeup(wpipe); 1158 } 1159 pipeselwakeup(wpipe); 1160 wpipe->pipe_state |= PIPE_WANTW; 1161 pipeunlock(wpipe); 1162 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH, 1163 "pipbww", 0); 1164 if (error) 1165 break; 1166 else 1167 continue; 1168 } 1169 1170 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1171 1172 /* Writes of size <= PIPE_BUF must be atomic. */ 1173 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 1174 space = 0; 1175 1176 if (space > 0) { 1177 int size; /* Transfer size */ 1178 int segsize; /* first segment to transfer */ 1179 1180 /* 1181 * Transfer size is minimum of uio transfer 1182 * and free space in pipe buffer. 1183 */ 1184 if (space > uio->uio_resid) 1185 size = uio->uio_resid; 1186 else 1187 size = space; 1188 /* 1189 * First segment to transfer is minimum of 1190 * transfer size and contiguous space in 1191 * pipe buffer. If first segment to transfer 1192 * is less than the transfer size, we've got 1193 * a wraparound in the buffer. 1194 */ 1195 segsize = wpipe->pipe_buffer.size - 1196 wpipe->pipe_buffer.in; 1197 if (segsize > size) 1198 segsize = size; 1199 1200 /* Transfer first segment */ 1201 1202 PIPE_UNLOCK(rpipe); 1203 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 1204 segsize, uio); 1205 PIPE_LOCK(rpipe); 1206 1207 if (error == 0 && segsize < size) { 1208 KASSERT(wpipe->pipe_buffer.in + segsize == 1209 wpipe->pipe_buffer.size, 1210 ("Pipe buffer wraparound disappeared")); 1211 /* 1212 * Transfer remaining part now, to 1213 * support atomic writes. Wraparound 1214 * happened. 1215 */ 1216 1217 PIPE_UNLOCK(rpipe); 1218 error = uiomove( 1219 &wpipe->pipe_buffer.buffer[0], 1220 size - segsize, uio); 1221 PIPE_LOCK(rpipe); 1222 } 1223 if (error == 0) { 1224 wpipe->pipe_buffer.in += size; 1225 if (wpipe->pipe_buffer.in >= 1226 wpipe->pipe_buffer.size) { 1227 KASSERT(wpipe->pipe_buffer.in == 1228 size - segsize + 1229 wpipe->pipe_buffer.size, 1230 ("Expected wraparound bad")); 1231 wpipe->pipe_buffer.in = size - segsize; 1232 } 1233 1234 wpipe->pipe_buffer.cnt += size; 1235 KASSERT(wpipe->pipe_buffer.cnt <= 1236 wpipe->pipe_buffer.size, 1237 ("Pipe buffer overflow")); 1238 } 1239 pipeunlock(wpipe); 1240 if (error != 0) 1241 break; 1242 } else { 1243 /* 1244 * If the "read-side" has been blocked, wake it up now. 1245 */ 1246 if (wpipe->pipe_state & PIPE_WANTR) { 1247 wpipe->pipe_state &= ~PIPE_WANTR; 1248 wakeup(wpipe); 1249 } 1250 1251 /* 1252 * don't block on non-blocking I/O 1253 */ 1254 if (fp->f_flag & FNONBLOCK) { 1255 error = EAGAIN; 1256 pipeunlock(wpipe); 1257 break; 1258 } 1259 1260 /* 1261 * We have no more space and have something to offer, 1262 * wake up select/poll. 1263 */ 1264 pipeselwakeup(wpipe); 1265 1266 wpipe->pipe_state |= PIPE_WANTW; 1267 pipeunlock(wpipe); 1268 error = msleep(wpipe, PIPE_MTX(rpipe), 1269 PRIBIO | PCATCH, "pipewr", 0); 1270 if (error != 0) 1271 break; 1272 } 1273 } 1274 1275 pipelock(wpipe, 0); 1276 --wpipe->pipe_busy; 1277 1278 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 1279 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 1280 wakeup(wpipe); 1281 } else if (wpipe->pipe_buffer.cnt > 0) { 1282 /* 1283 * If we have put any characters in the buffer, we wake up 1284 * the reader. 1285 */ 1286 if (wpipe->pipe_state & PIPE_WANTR) { 1287 wpipe->pipe_state &= ~PIPE_WANTR; 1288 wakeup(wpipe); 1289 } 1290 } 1291 1292 /* 1293 * Don't return EPIPE if any byte was written. 1294 * EINTR and other interrupts are handled by generic I/O layer. 1295 * Do not pretend that I/O succeeded for obvious user error 1296 * like EFAULT. 1297 */ 1298 if (uio->uio_resid != orig_resid && error == EPIPE) 1299 error = 0; 1300 1301 if (error == 0) 1302 vfs_timestamp(&wpipe->pipe_mtime); 1303 1304 /* 1305 * We have something to offer, 1306 * wake up select/poll. 1307 */ 1308 if (wpipe->pipe_buffer.cnt) 1309 pipeselwakeup(wpipe); 1310 1311 pipeunlock(wpipe); 1312 PIPE_UNLOCK(rpipe); 1313 return (error); 1314 } 1315 1316 /* ARGSUSED */ 1317 static int 1318 pipe_truncate(fp, length, active_cred, td) 1319 struct file *fp; 1320 off_t length; 1321 struct ucred *active_cred; 1322 struct thread *td; 1323 { 1324 struct pipe *cpipe; 1325 int error; 1326 1327 cpipe = fp->f_data; 1328 if (cpipe->pipe_state & PIPE_NAMED) 1329 error = vnops.fo_truncate(fp, length, active_cred, td); 1330 else 1331 error = invfo_truncate(fp, length, active_cred, td); 1332 return (error); 1333 } 1334 1335 /* 1336 * we implement a very minimal set of ioctls for compatibility with sockets. 1337 */ 1338 static int 1339 pipe_ioctl(fp, cmd, data, active_cred, td) 1340 struct file *fp; 1341 u_long cmd; 1342 void *data; 1343 struct ucred *active_cred; 1344 struct thread *td; 1345 { 1346 struct pipe *mpipe = fp->f_data; 1347 int error; 1348 1349 PIPE_LOCK(mpipe); 1350 1351 #ifdef MAC 1352 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data); 1353 if (error) { 1354 PIPE_UNLOCK(mpipe); 1355 return (error); 1356 } 1357 #endif 1358 1359 error = 0; 1360 switch (cmd) { 1361 1362 case FIONBIO: 1363 break; 1364 1365 case FIOASYNC: 1366 if (*(int *)data) { 1367 mpipe->pipe_state |= PIPE_ASYNC; 1368 } else { 1369 mpipe->pipe_state &= ~PIPE_ASYNC; 1370 } 1371 break; 1372 1373 case FIONREAD: 1374 if (!(fp->f_flag & FREAD)) { 1375 *(int *)data = 0; 1376 PIPE_UNLOCK(mpipe); 1377 return (0); 1378 } 1379 if (mpipe->pipe_state & PIPE_DIRECTW) 1380 *(int *)data = mpipe->pipe_map.cnt; 1381 else 1382 *(int *)data = mpipe->pipe_buffer.cnt; 1383 break; 1384 1385 case FIOSETOWN: 1386 PIPE_UNLOCK(mpipe); 1387 error = fsetown(*(int *)data, &mpipe->pipe_sigio); 1388 goto out_unlocked; 1389 1390 case FIOGETOWN: 1391 *(int *)data = fgetown(&mpipe->pipe_sigio); 1392 break; 1393 1394 /* This is deprecated, FIOSETOWN should be used instead. */ 1395 case TIOCSPGRP: 1396 PIPE_UNLOCK(mpipe); 1397 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio); 1398 goto out_unlocked; 1399 1400 /* This is deprecated, FIOGETOWN should be used instead. */ 1401 case TIOCGPGRP: 1402 *(int *)data = -fgetown(&mpipe->pipe_sigio); 1403 break; 1404 1405 default: 1406 error = ENOTTY; 1407 break; 1408 } 1409 PIPE_UNLOCK(mpipe); 1410 out_unlocked: 1411 return (error); 1412 } 1413 1414 static int 1415 pipe_poll(fp, events, active_cred, td) 1416 struct file *fp; 1417 int events; 1418 struct ucred *active_cred; 1419 struct thread *td; 1420 { 1421 struct pipe *rpipe; 1422 struct pipe *wpipe; 1423 int levents, revents; 1424 #ifdef MAC 1425 int error; 1426 #endif 1427 1428 revents = 0; 1429 rpipe = fp->f_data; 1430 wpipe = PIPE_PEER(rpipe); 1431 PIPE_LOCK(rpipe); 1432 #ifdef MAC 1433 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair); 1434 if (error) 1435 goto locked_error; 1436 #endif 1437 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) 1438 if ((rpipe->pipe_state & PIPE_DIRECTW) || 1439 (rpipe->pipe_buffer.cnt > 0)) 1440 revents |= events & (POLLIN | POLLRDNORM); 1441 1442 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) 1443 if (wpipe->pipe_present != PIPE_ACTIVE || 1444 (wpipe->pipe_state & PIPE_EOF) || 1445 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) && 1446 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF || 1447 wpipe->pipe_buffer.size == 0))) 1448 revents |= events & (POLLOUT | POLLWRNORM); 1449 1450 levents = events & 1451 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND); 1452 if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents && 1453 fp->f_seqcount == rpipe->pipe_wgen) 1454 events |= POLLINIGNEOF; 1455 1456 if ((events & POLLINIGNEOF) == 0) { 1457 if (rpipe->pipe_state & PIPE_EOF) { 1458 revents |= (events & (POLLIN | POLLRDNORM)); 1459 if (wpipe->pipe_present != PIPE_ACTIVE || 1460 (wpipe->pipe_state & PIPE_EOF)) 1461 revents |= POLLHUP; 1462 } 1463 } 1464 1465 if (revents == 0) { 1466 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) { 1467 selrecord(td, &rpipe->pipe_sel); 1468 if (SEL_WAITING(&rpipe->pipe_sel)) 1469 rpipe->pipe_state |= PIPE_SEL; 1470 } 1471 1472 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) { 1473 selrecord(td, &wpipe->pipe_sel); 1474 if (SEL_WAITING(&wpipe->pipe_sel)) 1475 wpipe->pipe_state |= PIPE_SEL; 1476 } 1477 } 1478 #ifdef MAC 1479 locked_error: 1480 #endif 1481 PIPE_UNLOCK(rpipe); 1482 1483 return (revents); 1484 } 1485 1486 /* 1487 * We shouldn't need locks here as we're doing a read and this should 1488 * be a natural race. 1489 */ 1490 static int 1491 pipe_stat(fp, ub, active_cred, td) 1492 struct file *fp; 1493 struct stat *ub; 1494 struct ucred *active_cred; 1495 struct thread *td; 1496 { 1497 struct pipe *pipe; 1498 int new_unr; 1499 #ifdef MAC 1500 int error; 1501 #endif 1502 1503 pipe = fp->f_data; 1504 PIPE_LOCK(pipe); 1505 #ifdef MAC 1506 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair); 1507 if (error) { 1508 PIPE_UNLOCK(pipe); 1509 return (error); 1510 } 1511 #endif 1512 1513 /* For named pipes ask the underlying filesystem. */ 1514 if (pipe->pipe_state & PIPE_NAMED) { 1515 PIPE_UNLOCK(pipe); 1516 return (vnops.fo_stat(fp, ub, active_cred, td)); 1517 } 1518 1519 /* 1520 * Lazily allocate an inode number for the pipe. Most pipe 1521 * users do not call fstat(2) on the pipe, which means that 1522 * postponing the inode allocation until it is must be 1523 * returned to userland is useful. If alloc_unr failed, 1524 * assign st_ino zero instead of returning an error. 1525 * Special pipe_ino values: 1526 * -1 - not yet initialized; 1527 * 0 - alloc_unr failed, return 0 as st_ino forever. 1528 */ 1529 if (pipe->pipe_ino == (ino_t)-1) { 1530 new_unr = alloc_unr(pipeino_unr); 1531 if (new_unr != -1) 1532 pipe->pipe_ino = new_unr; 1533 else 1534 pipe->pipe_ino = 0; 1535 } 1536 PIPE_UNLOCK(pipe); 1537 1538 bzero(ub, sizeof(*ub)); 1539 ub->st_mode = S_IFIFO; 1540 ub->st_blksize = PAGE_SIZE; 1541 if (pipe->pipe_state & PIPE_DIRECTW) 1542 ub->st_size = pipe->pipe_map.cnt; 1543 else 1544 ub->st_size = pipe->pipe_buffer.cnt; 1545 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize; 1546 ub->st_atim = pipe->pipe_atime; 1547 ub->st_mtim = pipe->pipe_mtime; 1548 ub->st_ctim = pipe->pipe_ctime; 1549 ub->st_uid = fp->f_cred->cr_uid; 1550 ub->st_gid = fp->f_cred->cr_gid; 1551 ub->st_dev = pipedev_ino; 1552 ub->st_ino = pipe->pipe_ino; 1553 /* 1554 * Left as 0: st_nlink, st_rdev, st_flags, st_gen. 1555 */ 1556 return (0); 1557 } 1558 1559 /* ARGSUSED */ 1560 static int 1561 pipe_close(fp, td) 1562 struct file *fp; 1563 struct thread *td; 1564 { 1565 1566 if (fp->f_vnode != NULL) 1567 return vnops.fo_close(fp, td); 1568 fp->f_ops = &badfileops; 1569 pipe_dtor(fp->f_data); 1570 fp->f_data = NULL; 1571 return (0); 1572 } 1573 1574 static int 1575 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td) 1576 { 1577 struct pipe *cpipe; 1578 int error; 1579 1580 cpipe = fp->f_data; 1581 if (cpipe->pipe_state & PIPE_NAMED) 1582 error = vn_chmod(fp, mode, active_cred, td); 1583 else 1584 error = invfo_chmod(fp, mode, active_cred, td); 1585 return (error); 1586 } 1587 1588 static int 1589 pipe_chown(fp, uid, gid, active_cred, td) 1590 struct file *fp; 1591 uid_t uid; 1592 gid_t gid; 1593 struct ucred *active_cred; 1594 struct thread *td; 1595 { 1596 struct pipe *cpipe; 1597 int error; 1598 1599 cpipe = fp->f_data; 1600 if (cpipe->pipe_state & PIPE_NAMED) 1601 error = vn_chown(fp, uid, gid, active_cred, td); 1602 else 1603 error = invfo_chown(fp, uid, gid, active_cred, td); 1604 return (error); 1605 } 1606 1607 static int 1608 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp) 1609 { 1610 struct pipe *pi; 1611 1612 if (fp->f_type == DTYPE_FIFO) 1613 return (vn_fill_kinfo(fp, kif, fdp)); 1614 kif->kf_type = KF_TYPE_PIPE; 1615 pi = fp->f_data; 1616 kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi; 1617 kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer; 1618 kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt; 1619 return (0); 1620 } 1621 1622 static void 1623 pipe_free_kmem(cpipe) 1624 struct pipe *cpipe; 1625 { 1626 1627 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), 1628 ("pipe_free_kmem: pipe mutex locked")); 1629 1630 if (cpipe->pipe_buffer.buffer != NULL) { 1631 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size); 1632 vm_map_remove(pipe_map, 1633 (vm_offset_t)cpipe->pipe_buffer.buffer, 1634 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size); 1635 cpipe->pipe_buffer.buffer = NULL; 1636 } 1637 #ifndef PIPE_NODIRECT 1638 { 1639 cpipe->pipe_map.cnt = 0; 1640 cpipe->pipe_map.pos = 0; 1641 cpipe->pipe_map.npages = 0; 1642 } 1643 #endif 1644 } 1645 1646 /* 1647 * shutdown the pipe 1648 */ 1649 static void 1650 pipeclose(cpipe) 1651 struct pipe *cpipe; 1652 { 1653 struct pipepair *pp; 1654 struct pipe *ppipe; 1655 1656 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL")); 1657 1658 PIPE_LOCK(cpipe); 1659 pipelock(cpipe, 0); 1660 pp = cpipe->pipe_pair; 1661 1662 pipeselwakeup(cpipe); 1663 1664 /* 1665 * If the other side is blocked, wake it up saying that 1666 * we want to close it down. 1667 */ 1668 cpipe->pipe_state |= PIPE_EOF; 1669 while (cpipe->pipe_busy) { 1670 wakeup(cpipe); 1671 cpipe->pipe_state |= PIPE_WANT; 1672 pipeunlock(cpipe); 1673 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0); 1674 pipelock(cpipe, 0); 1675 } 1676 1677 1678 /* 1679 * Disconnect from peer, if any. 1680 */ 1681 ppipe = cpipe->pipe_peer; 1682 if (ppipe->pipe_present == PIPE_ACTIVE) { 1683 pipeselwakeup(ppipe); 1684 1685 ppipe->pipe_state |= PIPE_EOF; 1686 wakeup(ppipe); 1687 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0); 1688 } 1689 1690 /* 1691 * Mark this endpoint as free. Release kmem resources. We 1692 * don't mark this endpoint as unused until we've finished 1693 * doing that, or the pipe might disappear out from under 1694 * us. 1695 */ 1696 PIPE_UNLOCK(cpipe); 1697 pipe_free_kmem(cpipe); 1698 PIPE_LOCK(cpipe); 1699 cpipe->pipe_present = PIPE_CLOSING; 1700 pipeunlock(cpipe); 1701 1702 /* 1703 * knlist_clear() may sleep dropping the PIPE_MTX. Set the 1704 * PIPE_FINALIZED, that allows other end to free the 1705 * pipe_pair, only after the knotes are completely dismantled. 1706 */ 1707 knlist_clear(&cpipe->pipe_sel.si_note, 1); 1708 cpipe->pipe_present = PIPE_FINALIZED; 1709 seldrain(&cpipe->pipe_sel); 1710 knlist_destroy(&cpipe->pipe_sel.si_note); 1711 1712 /* 1713 * If both endpoints are now closed, release the memory for the 1714 * pipe pair. If not, unlock. 1715 */ 1716 if (ppipe->pipe_present == PIPE_FINALIZED) { 1717 PIPE_UNLOCK(cpipe); 1718 #ifdef MAC 1719 mac_pipe_destroy(pp); 1720 #endif 1721 uma_zfree(pipe_zone, cpipe->pipe_pair); 1722 } else 1723 PIPE_UNLOCK(cpipe); 1724 } 1725 1726 /*ARGSUSED*/ 1727 static int 1728 pipe_kqfilter(struct file *fp, struct knote *kn) 1729 { 1730 struct pipe *cpipe; 1731 1732 /* 1733 * If a filter is requested that is not supported by this file 1734 * descriptor, don't return an error, but also don't ever generate an 1735 * event. 1736 */ 1737 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) { 1738 kn->kn_fop = &pipe_nfiltops; 1739 return (0); 1740 } 1741 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) { 1742 kn->kn_fop = &pipe_nfiltops; 1743 return (0); 1744 } 1745 cpipe = fp->f_data; 1746 PIPE_LOCK(cpipe); 1747 switch (kn->kn_filter) { 1748 case EVFILT_READ: 1749 kn->kn_fop = &pipe_rfiltops; 1750 break; 1751 case EVFILT_WRITE: 1752 kn->kn_fop = &pipe_wfiltops; 1753 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) { 1754 /* other end of pipe has been closed */ 1755 PIPE_UNLOCK(cpipe); 1756 return (EPIPE); 1757 } 1758 cpipe = PIPE_PEER(cpipe); 1759 break; 1760 default: 1761 PIPE_UNLOCK(cpipe); 1762 return (EINVAL); 1763 } 1764 1765 kn->kn_hook = cpipe; 1766 knlist_add(&cpipe->pipe_sel.si_note, kn, 1); 1767 PIPE_UNLOCK(cpipe); 1768 return (0); 1769 } 1770 1771 static void 1772 filt_pipedetach(struct knote *kn) 1773 { 1774 struct pipe *cpipe = kn->kn_hook; 1775 1776 PIPE_LOCK(cpipe); 1777 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1); 1778 PIPE_UNLOCK(cpipe); 1779 } 1780 1781 /*ARGSUSED*/ 1782 static int 1783 filt_piperead(struct knote *kn, long hint) 1784 { 1785 struct pipe *rpipe = kn->kn_hook; 1786 struct pipe *wpipe = rpipe->pipe_peer; 1787 int ret; 1788 1789 PIPE_LOCK_ASSERT(rpipe, MA_OWNED); 1790 kn->kn_data = rpipe->pipe_buffer.cnt; 1791 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) 1792 kn->kn_data = rpipe->pipe_map.cnt; 1793 1794 if ((rpipe->pipe_state & PIPE_EOF) || 1795 wpipe->pipe_present != PIPE_ACTIVE || 1796 (wpipe->pipe_state & PIPE_EOF)) { 1797 kn->kn_flags |= EV_EOF; 1798 return (1); 1799 } 1800 ret = kn->kn_data > 0; 1801 return ret; 1802 } 1803 1804 /*ARGSUSED*/ 1805 static int 1806 filt_pipewrite(struct knote *kn, long hint) 1807 { 1808 struct pipe *wpipe; 1809 1810 wpipe = kn->kn_hook; 1811 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 1812 if (wpipe->pipe_present != PIPE_ACTIVE || 1813 (wpipe->pipe_state & PIPE_EOF)) { 1814 kn->kn_data = 0; 1815 kn->kn_flags |= EV_EOF; 1816 return (1); 1817 } 1818 kn->kn_data = (wpipe->pipe_buffer.size > 0) ? 1819 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF; 1820 if (wpipe->pipe_state & PIPE_DIRECTW) 1821 kn->kn_data = 0; 1822 1823 return (kn->kn_data >= PIPE_BUF); 1824 } 1825 1826 static void 1827 filt_pipedetach_notsup(struct knote *kn) 1828 { 1829 1830 } 1831 1832 static int 1833 filt_pipenotsup(struct knote *kn, long hint) 1834 { 1835 1836 return (0); 1837 } 1838