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]) 401 { 402 403 return (kern_pipe2(td, fildes, 0)); 404 } 405 406 int 407 kern_pipe2(struct thread *td, int fildes[2], int flags) 408 { 409 struct file *rf, *wf; 410 struct pipe *rpipe, *wpipe; 411 struct pipepair *pp; 412 int fd, fflags, error; 413 414 pipe_paircreate(td, &pp); 415 rpipe = &pp->pp_rpipe; 416 wpipe = &pp->pp_wpipe; 417 error = falloc(td, &rf, &fd, flags); 418 if (error) { 419 pipeclose(rpipe); 420 pipeclose(wpipe); 421 return (error); 422 } 423 /* An extra reference on `rf' has been held for us by falloc(). */ 424 fildes[0] = fd; 425 426 fflags = FREAD | FWRITE; 427 if ((flags & O_NONBLOCK) != 0) 428 fflags |= FNONBLOCK; 429 430 /* 431 * Warning: once we've gotten past allocation of the fd for the 432 * read-side, we can only drop the read side via fdrop() in order 433 * to avoid races against processes which manage to dup() the read 434 * side while we are blocked trying to allocate the write side. 435 */ 436 finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops); 437 error = falloc(td, &wf, &fd, flags); 438 if (error) { 439 fdclose(td, rf, fildes[0]); 440 fdrop(rf, td); 441 /* rpipe has been closed by fdrop(). */ 442 pipeclose(wpipe); 443 return (error); 444 } 445 /* An extra reference on `wf' has been held for us by falloc(). */ 446 finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops); 447 fdrop(wf, td); 448 fildes[1] = fd; 449 fdrop(rf, td); 450 451 return (0); 452 } 453 454 /* ARGSUSED */ 455 int 456 sys_pipe(struct thread *td, struct pipe_args *uap) 457 { 458 int error; 459 int fildes[2]; 460 461 error = kern_pipe(td, fildes); 462 if (error) 463 return (error); 464 465 td->td_retval[0] = fildes[0]; 466 td->td_retval[1] = fildes[1]; 467 468 return (0); 469 } 470 471 int 472 sys_pipe2(struct thread *td, struct pipe2_args *uap) 473 { 474 int error, fildes[2]; 475 476 if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK)) 477 return (EINVAL); 478 error = kern_pipe2(td, fildes, uap->flags); 479 if (error) 480 return (error); 481 error = copyout(fildes, uap->fildes, 2 * sizeof(int)); 482 if (error) { 483 (void)kern_close(td, fildes[0]); 484 (void)kern_close(td, fildes[1]); 485 } 486 return (error); 487 } 488 489 /* 490 * Allocate kva for pipe circular buffer, the space is pageable 491 * This routine will 'realloc' the size of a pipe safely, if it fails 492 * it will retain the old buffer. 493 * If it fails it will return ENOMEM. 494 */ 495 static int 496 pipespace_new(cpipe, size) 497 struct pipe *cpipe; 498 int size; 499 { 500 caddr_t buffer; 501 int error, cnt, firstseg; 502 static int curfail = 0; 503 static struct timeval lastfail; 504 505 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked")); 506 KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW), 507 ("pipespace: resize of direct writes not allowed")); 508 retry: 509 cnt = cpipe->pipe_buffer.cnt; 510 if (cnt > size) 511 size = cnt; 512 513 size = round_page(size); 514 buffer = (caddr_t) vm_map_min(pipe_map); 515 516 error = vm_map_find(pipe_map, NULL, 0, 517 (vm_offset_t *) &buffer, size, 0, VMFS_ANY_SPACE, 518 VM_PROT_ALL, VM_PROT_ALL, 0); 519 if (error != KERN_SUCCESS) { 520 if ((cpipe->pipe_buffer.buffer == NULL) && 521 (size > SMALL_PIPE_SIZE)) { 522 size = SMALL_PIPE_SIZE; 523 pipefragretry++; 524 goto retry; 525 } 526 if (cpipe->pipe_buffer.buffer == NULL) { 527 pipeallocfail++; 528 if (ppsratecheck(&lastfail, &curfail, 1)) 529 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n"); 530 } else { 531 piperesizefail++; 532 } 533 return (ENOMEM); 534 } 535 536 /* copy data, then free old resources if we're resizing */ 537 if (cnt > 0) { 538 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) { 539 firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out; 540 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 541 buffer, firstseg); 542 if ((cnt - firstseg) > 0) 543 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg], 544 cpipe->pipe_buffer.in); 545 } else { 546 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 547 buffer, cnt); 548 } 549 } 550 pipe_free_kmem(cpipe); 551 cpipe->pipe_buffer.buffer = buffer; 552 cpipe->pipe_buffer.size = size; 553 cpipe->pipe_buffer.in = cnt; 554 cpipe->pipe_buffer.out = 0; 555 cpipe->pipe_buffer.cnt = cnt; 556 atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size); 557 return (0); 558 } 559 560 /* 561 * Wrapper for pipespace_new() that performs locking assertions. 562 */ 563 static int 564 pipespace(cpipe, size) 565 struct pipe *cpipe; 566 int size; 567 { 568 569 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 570 ("Unlocked pipe passed to pipespace")); 571 return (pipespace_new(cpipe, size)); 572 } 573 574 /* 575 * lock a pipe for I/O, blocking other access 576 */ 577 static __inline int 578 pipelock(cpipe, catch) 579 struct pipe *cpipe; 580 int catch; 581 { 582 int error; 583 584 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 585 while (cpipe->pipe_state & PIPE_LOCKFL) { 586 cpipe->pipe_state |= PIPE_LWANT; 587 error = msleep(cpipe, PIPE_MTX(cpipe), 588 catch ? (PRIBIO | PCATCH) : PRIBIO, 589 "pipelk", 0); 590 if (error != 0) 591 return (error); 592 } 593 cpipe->pipe_state |= PIPE_LOCKFL; 594 return (0); 595 } 596 597 /* 598 * unlock a pipe I/O lock 599 */ 600 static __inline void 601 pipeunlock(cpipe) 602 struct pipe *cpipe; 603 { 604 605 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 606 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 607 ("Unlocked pipe passed to pipeunlock")); 608 cpipe->pipe_state &= ~PIPE_LOCKFL; 609 if (cpipe->pipe_state & PIPE_LWANT) { 610 cpipe->pipe_state &= ~PIPE_LWANT; 611 wakeup(cpipe); 612 } 613 } 614 615 void 616 pipeselwakeup(cpipe) 617 struct pipe *cpipe; 618 { 619 620 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 621 if (cpipe->pipe_state & PIPE_SEL) { 622 selwakeuppri(&cpipe->pipe_sel, PSOCK); 623 if (!SEL_WAITING(&cpipe->pipe_sel)) 624 cpipe->pipe_state &= ~PIPE_SEL; 625 } 626 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) 627 pgsigio(&cpipe->pipe_sigio, SIGIO, 0); 628 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0); 629 } 630 631 /* 632 * Initialize and allocate VM and memory for pipe. The structure 633 * will start out zero'd from the ctor, so we just manage the kmem. 634 */ 635 static void 636 pipe_create(pipe, backing) 637 struct pipe *pipe; 638 int backing; 639 { 640 641 if (backing) { 642 /* 643 * Note that these functions can fail if pipe map is exhausted 644 * (as a result of too many pipes created), but we ignore the 645 * error as it is not fatal and could be provoked by 646 * unprivileged users. The only consequence is worse performance 647 * with given pipe. 648 */ 649 if (amountpipekva > maxpipekva / 2) 650 (void)pipespace_new(pipe, SMALL_PIPE_SIZE); 651 else 652 (void)pipespace_new(pipe, PIPE_SIZE); 653 } 654 655 pipe->pipe_ino = -1; 656 } 657 658 /* ARGSUSED */ 659 static int 660 pipe_read(fp, uio, active_cred, flags, td) 661 struct file *fp; 662 struct uio *uio; 663 struct ucred *active_cred; 664 struct thread *td; 665 int flags; 666 { 667 struct pipe *rpipe; 668 int error; 669 int nread = 0; 670 int size; 671 672 rpipe = fp->f_data; 673 PIPE_LOCK(rpipe); 674 ++rpipe->pipe_busy; 675 error = pipelock(rpipe, 1); 676 if (error) 677 goto unlocked_error; 678 679 #ifdef MAC 680 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair); 681 if (error) 682 goto locked_error; 683 #endif 684 if (amountpipekva > (3 * maxpipekva) / 4) { 685 if (!(rpipe->pipe_state & PIPE_DIRECTW) && 686 (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) && 687 (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) && 688 (piperesizeallowed == 1)) { 689 PIPE_UNLOCK(rpipe); 690 pipespace(rpipe, SMALL_PIPE_SIZE); 691 PIPE_LOCK(rpipe); 692 } 693 } 694 695 while (uio->uio_resid) { 696 /* 697 * normal pipe buffer receive 698 */ 699 if (rpipe->pipe_buffer.cnt > 0) { 700 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 701 if (size > rpipe->pipe_buffer.cnt) 702 size = rpipe->pipe_buffer.cnt; 703 if (size > uio->uio_resid) 704 size = uio->uio_resid; 705 706 PIPE_UNLOCK(rpipe); 707 error = uiomove( 708 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 709 size, uio); 710 PIPE_LOCK(rpipe); 711 if (error) 712 break; 713 714 rpipe->pipe_buffer.out += size; 715 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 716 rpipe->pipe_buffer.out = 0; 717 718 rpipe->pipe_buffer.cnt -= size; 719 720 /* 721 * If there is no more to read in the pipe, reset 722 * its pointers to the beginning. This improves 723 * cache hit stats. 724 */ 725 if (rpipe->pipe_buffer.cnt == 0) { 726 rpipe->pipe_buffer.in = 0; 727 rpipe->pipe_buffer.out = 0; 728 } 729 nread += size; 730 #ifndef PIPE_NODIRECT 731 /* 732 * Direct copy, bypassing a kernel buffer. 733 */ 734 } else if ((size = rpipe->pipe_map.cnt) && 735 (rpipe->pipe_state & PIPE_DIRECTW)) { 736 if (size > uio->uio_resid) 737 size = (u_int) uio->uio_resid; 738 739 PIPE_UNLOCK(rpipe); 740 error = uiomove_fromphys(rpipe->pipe_map.ms, 741 rpipe->pipe_map.pos, size, uio); 742 PIPE_LOCK(rpipe); 743 if (error) 744 break; 745 nread += size; 746 rpipe->pipe_map.pos += size; 747 rpipe->pipe_map.cnt -= size; 748 if (rpipe->pipe_map.cnt == 0) { 749 rpipe->pipe_state &= ~(PIPE_DIRECTW|PIPE_WANTW); 750 wakeup(rpipe); 751 } 752 #endif 753 } else { 754 /* 755 * detect EOF condition 756 * read returns 0 on EOF, no need to set error 757 */ 758 if (rpipe->pipe_state & PIPE_EOF) 759 break; 760 761 /* 762 * If the "write-side" has been blocked, wake it up now. 763 */ 764 if (rpipe->pipe_state & PIPE_WANTW) { 765 rpipe->pipe_state &= ~PIPE_WANTW; 766 wakeup(rpipe); 767 } 768 769 /* 770 * Break if some data was read. 771 */ 772 if (nread > 0) 773 break; 774 775 /* 776 * Unlock the pipe buffer for our remaining processing. 777 * We will either break out with an error or we will 778 * sleep and relock to loop. 779 */ 780 pipeunlock(rpipe); 781 782 /* 783 * Handle non-blocking mode operation or 784 * wait for more data. 785 */ 786 if (fp->f_flag & FNONBLOCK) { 787 error = EAGAIN; 788 } else { 789 rpipe->pipe_state |= PIPE_WANTR; 790 if ((error = msleep(rpipe, PIPE_MTX(rpipe), 791 PRIBIO | PCATCH, 792 "piperd", 0)) == 0) 793 error = pipelock(rpipe, 1); 794 } 795 if (error) 796 goto unlocked_error; 797 } 798 } 799 #ifdef MAC 800 locked_error: 801 #endif 802 pipeunlock(rpipe); 803 804 /* XXX: should probably do this before getting any locks. */ 805 if (error == 0) 806 vfs_timestamp(&rpipe->pipe_atime); 807 unlocked_error: 808 --rpipe->pipe_busy; 809 810 /* 811 * PIPE_WANT processing only makes sense if pipe_busy is 0. 812 */ 813 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 814 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 815 wakeup(rpipe); 816 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 817 /* 818 * Handle write blocking hysteresis. 819 */ 820 if (rpipe->pipe_state & PIPE_WANTW) { 821 rpipe->pipe_state &= ~PIPE_WANTW; 822 wakeup(rpipe); 823 } 824 } 825 826 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF) 827 pipeselwakeup(rpipe); 828 829 PIPE_UNLOCK(rpipe); 830 return (error); 831 } 832 833 #ifndef PIPE_NODIRECT 834 /* 835 * Map the sending processes' buffer into kernel space and wire it. 836 * This is similar to a physical write operation. 837 */ 838 static int 839 pipe_build_write_buffer(wpipe, uio) 840 struct pipe *wpipe; 841 struct uio *uio; 842 { 843 u_int size; 844 int i; 845 846 PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED); 847 KASSERT(wpipe->pipe_state & PIPE_DIRECTW, 848 ("Clone attempt on non-direct write pipe!")); 849 850 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size) 851 size = wpipe->pipe_buffer.size; 852 else 853 size = uio->uio_iov->iov_len; 854 855 if ((i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 856 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ, 857 wpipe->pipe_map.ms, PIPENPAGES)) < 0) 858 return (EFAULT); 859 860 /* 861 * set up the control block 862 */ 863 wpipe->pipe_map.npages = i; 864 wpipe->pipe_map.pos = 865 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 866 wpipe->pipe_map.cnt = size; 867 868 /* 869 * and update the uio data 870 */ 871 872 uio->uio_iov->iov_len -= size; 873 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size; 874 if (uio->uio_iov->iov_len == 0) 875 uio->uio_iov++; 876 uio->uio_resid -= size; 877 uio->uio_offset += size; 878 return (0); 879 } 880 881 /* 882 * unmap and unwire the process buffer 883 */ 884 static void 885 pipe_destroy_write_buffer(wpipe) 886 struct pipe *wpipe; 887 { 888 889 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 890 vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages); 891 wpipe->pipe_map.npages = 0; 892 } 893 894 /* 895 * In the case of a signal, the writing process might go away. This 896 * code copies the data into the circular buffer so that the source 897 * pages can be freed without loss of data. 898 */ 899 static void 900 pipe_clone_write_buffer(wpipe) 901 struct pipe *wpipe; 902 { 903 struct uio uio; 904 struct iovec iov; 905 int size; 906 int pos; 907 908 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 909 size = wpipe->pipe_map.cnt; 910 pos = wpipe->pipe_map.pos; 911 912 wpipe->pipe_buffer.in = size; 913 wpipe->pipe_buffer.out = 0; 914 wpipe->pipe_buffer.cnt = size; 915 wpipe->pipe_state &= ~PIPE_DIRECTW; 916 917 PIPE_UNLOCK(wpipe); 918 iov.iov_base = wpipe->pipe_buffer.buffer; 919 iov.iov_len = size; 920 uio.uio_iov = &iov; 921 uio.uio_iovcnt = 1; 922 uio.uio_offset = 0; 923 uio.uio_resid = size; 924 uio.uio_segflg = UIO_SYSSPACE; 925 uio.uio_rw = UIO_READ; 926 uio.uio_td = curthread; 927 uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio); 928 PIPE_LOCK(wpipe); 929 pipe_destroy_write_buffer(wpipe); 930 } 931 932 /* 933 * This implements the pipe buffer write mechanism. Note that only 934 * a direct write OR a normal pipe write can be pending at any given time. 935 * If there are any characters in the pipe buffer, the direct write will 936 * be deferred until the receiving process grabs all of the bytes from 937 * the pipe buffer. Then the direct mapping write is set-up. 938 */ 939 static int 940 pipe_direct_write(wpipe, uio) 941 struct pipe *wpipe; 942 struct uio *uio; 943 { 944 int error; 945 946 retry: 947 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 948 error = pipelock(wpipe, 1); 949 if (wpipe->pipe_state & PIPE_EOF) 950 error = EPIPE; 951 if (error) { 952 pipeunlock(wpipe); 953 goto error1; 954 } 955 while (wpipe->pipe_state & PIPE_DIRECTW) { 956 if (wpipe->pipe_state & PIPE_WANTR) { 957 wpipe->pipe_state &= ~PIPE_WANTR; 958 wakeup(wpipe); 959 } 960 pipeselwakeup(wpipe); 961 wpipe->pipe_state |= PIPE_WANTW; 962 pipeunlock(wpipe); 963 error = msleep(wpipe, PIPE_MTX(wpipe), 964 PRIBIO | PCATCH, "pipdww", 0); 965 if (error) 966 goto error1; 967 else 968 goto retry; 969 } 970 wpipe->pipe_map.cnt = 0; /* transfer not ready yet */ 971 if (wpipe->pipe_buffer.cnt > 0) { 972 if (wpipe->pipe_state & PIPE_WANTR) { 973 wpipe->pipe_state &= ~PIPE_WANTR; 974 wakeup(wpipe); 975 } 976 pipeselwakeup(wpipe); 977 wpipe->pipe_state |= PIPE_WANTW; 978 pipeunlock(wpipe); 979 error = msleep(wpipe, PIPE_MTX(wpipe), 980 PRIBIO | PCATCH, "pipdwc", 0); 981 if (error) 982 goto error1; 983 else 984 goto retry; 985 } 986 987 wpipe->pipe_state |= PIPE_DIRECTW; 988 989 PIPE_UNLOCK(wpipe); 990 error = pipe_build_write_buffer(wpipe, uio); 991 PIPE_LOCK(wpipe); 992 if (error) { 993 wpipe->pipe_state &= ~PIPE_DIRECTW; 994 pipeunlock(wpipe); 995 goto error1; 996 } 997 998 error = 0; 999 while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) { 1000 if (wpipe->pipe_state & PIPE_EOF) { 1001 pipe_destroy_write_buffer(wpipe); 1002 pipeselwakeup(wpipe); 1003 pipeunlock(wpipe); 1004 error = EPIPE; 1005 goto error1; 1006 } 1007 if (wpipe->pipe_state & PIPE_WANTR) { 1008 wpipe->pipe_state &= ~PIPE_WANTR; 1009 wakeup(wpipe); 1010 } 1011 pipeselwakeup(wpipe); 1012 wpipe->pipe_state |= PIPE_WANTW; 1013 pipeunlock(wpipe); 1014 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH, 1015 "pipdwt", 0); 1016 pipelock(wpipe, 0); 1017 } 1018 1019 if (wpipe->pipe_state & PIPE_EOF) 1020 error = EPIPE; 1021 if (wpipe->pipe_state & PIPE_DIRECTW) { 1022 /* 1023 * this bit of trickery substitutes a kernel buffer for 1024 * the process that might be going away. 1025 */ 1026 pipe_clone_write_buffer(wpipe); 1027 } else { 1028 pipe_destroy_write_buffer(wpipe); 1029 } 1030 pipeunlock(wpipe); 1031 return (error); 1032 1033 error1: 1034 wakeup(wpipe); 1035 return (error); 1036 } 1037 #endif 1038 1039 static int 1040 pipe_write(fp, uio, active_cred, flags, td) 1041 struct file *fp; 1042 struct uio *uio; 1043 struct ucred *active_cred; 1044 struct thread *td; 1045 int flags; 1046 { 1047 int error = 0; 1048 int desiredsize; 1049 ssize_t orig_resid; 1050 struct pipe *wpipe, *rpipe; 1051 1052 rpipe = fp->f_data; 1053 wpipe = PIPE_PEER(rpipe); 1054 PIPE_LOCK(rpipe); 1055 error = pipelock(wpipe, 1); 1056 if (error) { 1057 PIPE_UNLOCK(rpipe); 1058 return (error); 1059 } 1060 /* 1061 * detect loss of pipe read side, issue SIGPIPE if lost. 1062 */ 1063 if (wpipe->pipe_present != PIPE_ACTIVE || 1064 (wpipe->pipe_state & PIPE_EOF)) { 1065 pipeunlock(wpipe); 1066 PIPE_UNLOCK(rpipe); 1067 return (EPIPE); 1068 } 1069 #ifdef MAC 1070 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair); 1071 if (error) { 1072 pipeunlock(wpipe); 1073 PIPE_UNLOCK(rpipe); 1074 return (error); 1075 } 1076 #endif 1077 ++wpipe->pipe_busy; 1078 1079 /* Choose a larger size if it's advantageous */ 1080 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size); 1081 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) { 1082 if (piperesizeallowed != 1) 1083 break; 1084 if (amountpipekva > maxpipekva / 2) 1085 break; 1086 if (desiredsize == BIG_PIPE_SIZE) 1087 break; 1088 desiredsize = desiredsize * 2; 1089 } 1090 1091 /* Choose a smaller size if we're in a OOM situation */ 1092 if ((amountpipekva > (3 * maxpipekva) / 4) && 1093 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) && 1094 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) && 1095 (piperesizeallowed == 1)) 1096 desiredsize = SMALL_PIPE_SIZE; 1097 1098 /* Resize if the above determined that a new size was necessary */ 1099 if ((desiredsize != wpipe->pipe_buffer.size) && 1100 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) { 1101 PIPE_UNLOCK(wpipe); 1102 pipespace(wpipe, desiredsize); 1103 PIPE_LOCK(wpipe); 1104 } 1105 if (wpipe->pipe_buffer.size == 0) { 1106 /* 1107 * This can only happen for reverse direction use of pipes 1108 * in a complete OOM situation. 1109 */ 1110 error = ENOMEM; 1111 --wpipe->pipe_busy; 1112 pipeunlock(wpipe); 1113 PIPE_UNLOCK(wpipe); 1114 return (error); 1115 } 1116 1117 pipeunlock(wpipe); 1118 1119 orig_resid = uio->uio_resid; 1120 1121 while (uio->uio_resid) { 1122 int space; 1123 1124 pipelock(wpipe, 0); 1125 if (wpipe->pipe_state & PIPE_EOF) { 1126 pipeunlock(wpipe); 1127 error = EPIPE; 1128 break; 1129 } 1130 #ifndef PIPE_NODIRECT 1131 /* 1132 * If the transfer is large, we can gain performance if 1133 * we do process-to-process copies directly. 1134 * If the write is non-blocking, we don't use the 1135 * direct write mechanism. 1136 * 1137 * The direct write mechanism will detect the reader going 1138 * away on us. 1139 */ 1140 if (uio->uio_segflg == UIO_USERSPACE && 1141 uio->uio_iov->iov_len >= PIPE_MINDIRECT && 1142 wpipe->pipe_buffer.size >= PIPE_MINDIRECT && 1143 (fp->f_flag & FNONBLOCK) == 0) { 1144 pipeunlock(wpipe); 1145 error = pipe_direct_write(wpipe, uio); 1146 if (error) 1147 break; 1148 continue; 1149 } 1150 #endif 1151 1152 /* 1153 * Pipe buffered writes cannot be coincidental with 1154 * direct writes. We wait until the currently executing 1155 * direct write is completed before we start filling the 1156 * pipe buffer. We break out if a signal occurs or the 1157 * reader goes away. 1158 */ 1159 if (wpipe->pipe_state & PIPE_DIRECTW) { 1160 if (wpipe->pipe_state & PIPE_WANTR) { 1161 wpipe->pipe_state &= ~PIPE_WANTR; 1162 wakeup(wpipe); 1163 } 1164 pipeselwakeup(wpipe); 1165 wpipe->pipe_state |= PIPE_WANTW; 1166 pipeunlock(wpipe); 1167 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH, 1168 "pipbww", 0); 1169 if (error) 1170 break; 1171 else 1172 continue; 1173 } 1174 1175 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1176 1177 /* Writes of size <= PIPE_BUF must be atomic. */ 1178 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 1179 space = 0; 1180 1181 if (space > 0) { 1182 int size; /* Transfer size */ 1183 int segsize; /* first segment to transfer */ 1184 1185 /* 1186 * Transfer size is minimum of uio transfer 1187 * and free space in pipe buffer. 1188 */ 1189 if (space > uio->uio_resid) 1190 size = uio->uio_resid; 1191 else 1192 size = space; 1193 /* 1194 * First segment to transfer is minimum of 1195 * transfer size and contiguous space in 1196 * pipe buffer. If first segment to transfer 1197 * is less than the transfer size, we've got 1198 * a wraparound in the buffer. 1199 */ 1200 segsize = wpipe->pipe_buffer.size - 1201 wpipe->pipe_buffer.in; 1202 if (segsize > size) 1203 segsize = size; 1204 1205 /* Transfer first segment */ 1206 1207 PIPE_UNLOCK(rpipe); 1208 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 1209 segsize, uio); 1210 PIPE_LOCK(rpipe); 1211 1212 if (error == 0 && segsize < size) { 1213 KASSERT(wpipe->pipe_buffer.in + segsize == 1214 wpipe->pipe_buffer.size, 1215 ("Pipe buffer wraparound disappeared")); 1216 /* 1217 * Transfer remaining part now, to 1218 * support atomic writes. Wraparound 1219 * happened. 1220 */ 1221 1222 PIPE_UNLOCK(rpipe); 1223 error = uiomove( 1224 &wpipe->pipe_buffer.buffer[0], 1225 size - segsize, uio); 1226 PIPE_LOCK(rpipe); 1227 } 1228 if (error == 0) { 1229 wpipe->pipe_buffer.in += size; 1230 if (wpipe->pipe_buffer.in >= 1231 wpipe->pipe_buffer.size) { 1232 KASSERT(wpipe->pipe_buffer.in == 1233 size - segsize + 1234 wpipe->pipe_buffer.size, 1235 ("Expected wraparound bad")); 1236 wpipe->pipe_buffer.in = size - segsize; 1237 } 1238 1239 wpipe->pipe_buffer.cnt += size; 1240 KASSERT(wpipe->pipe_buffer.cnt <= 1241 wpipe->pipe_buffer.size, 1242 ("Pipe buffer overflow")); 1243 } 1244 pipeunlock(wpipe); 1245 if (error != 0) 1246 break; 1247 } else { 1248 /* 1249 * If the "read-side" has been blocked, wake it up now. 1250 */ 1251 if (wpipe->pipe_state & PIPE_WANTR) { 1252 wpipe->pipe_state &= ~PIPE_WANTR; 1253 wakeup(wpipe); 1254 } 1255 1256 /* 1257 * don't block on non-blocking I/O 1258 */ 1259 if (fp->f_flag & FNONBLOCK) { 1260 error = EAGAIN; 1261 pipeunlock(wpipe); 1262 break; 1263 } 1264 1265 /* 1266 * We have no more space and have something to offer, 1267 * wake up select/poll. 1268 */ 1269 pipeselwakeup(wpipe); 1270 1271 wpipe->pipe_state |= PIPE_WANTW; 1272 pipeunlock(wpipe); 1273 error = msleep(wpipe, PIPE_MTX(rpipe), 1274 PRIBIO | PCATCH, "pipewr", 0); 1275 if (error != 0) 1276 break; 1277 } 1278 } 1279 1280 pipelock(wpipe, 0); 1281 --wpipe->pipe_busy; 1282 1283 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 1284 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 1285 wakeup(wpipe); 1286 } else if (wpipe->pipe_buffer.cnt > 0) { 1287 /* 1288 * If we have put any characters in the buffer, we wake up 1289 * the reader. 1290 */ 1291 if (wpipe->pipe_state & PIPE_WANTR) { 1292 wpipe->pipe_state &= ~PIPE_WANTR; 1293 wakeup(wpipe); 1294 } 1295 } 1296 1297 /* 1298 * Don't return EPIPE if any byte was written. 1299 * EINTR and other interrupts are handled by generic I/O layer. 1300 * Do not pretend that I/O succeeded for obvious user error 1301 * like EFAULT. 1302 */ 1303 if (uio->uio_resid != orig_resid && error == EPIPE) 1304 error = 0; 1305 1306 if (error == 0) 1307 vfs_timestamp(&wpipe->pipe_mtime); 1308 1309 /* 1310 * We have something to offer, 1311 * wake up select/poll. 1312 */ 1313 if (wpipe->pipe_buffer.cnt) 1314 pipeselwakeup(wpipe); 1315 1316 pipeunlock(wpipe); 1317 PIPE_UNLOCK(rpipe); 1318 return (error); 1319 } 1320 1321 /* ARGSUSED */ 1322 static int 1323 pipe_truncate(fp, length, active_cred, td) 1324 struct file *fp; 1325 off_t length; 1326 struct ucred *active_cred; 1327 struct thread *td; 1328 { 1329 struct pipe *cpipe; 1330 int error; 1331 1332 cpipe = fp->f_data; 1333 if (cpipe->pipe_state & PIPE_NAMED) 1334 error = vnops.fo_truncate(fp, length, active_cred, td); 1335 else 1336 error = invfo_truncate(fp, length, active_cred, td); 1337 return (error); 1338 } 1339 1340 /* 1341 * we implement a very minimal set of ioctls for compatibility with sockets. 1342 */ 1343 static int 1344 pipe_ioctl(fp, cmd, data, active_cred, td) 1345 struct file *fp; 1346 u_long cmd; 1347 void *data; 1348 struct ucred *active_cred; 1349 struct thread *td; 1350 { 1351 struct pipe *mpipe = fp->f_data; 1352 int error; 1353 1354 PIPE_LOCK(mpipe); 1355 1356 #ifdef MAC 1357 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data); 1358 if (error) { 1359 PIPE_UNLOCK(mpipe); 1360 return (error); 1361 } 1362 #endif 1363 1364 error = 0; 1365 switch (cmd) { 1366 1367 case FIONBIO: 1368 break; 1369 1370 case FIOASYNC: 1371 if (*(int *)data) { 1372 mpipe->pipe_state |= PIPE_ASYNC; 1373 } else { 1374 mpipe->pipe_state &= ~PIPE_ASYNC; 1375 } 1376 break; 1377 1378 case FIONREAD: 1379 if (!(fp->f_flag & FREAD)) { 1380 *(int *)data = 0; 1381 PIPE_UNLOCK(mpipe); 1382 return (0); 1383 } 1384 if (mpipe->pipe_state & PIPE_DIRECTW) 1385 *(int *)data = mpipe->pipe_map.cnt; 1386 else 1387 *(int *)data = mpipe->pipe_buffer.cnt; 1388 break; 1389 1390 case FIOSETOWN: 1391 PIPE_UNLOCK(mpipe); 1392 error = fsetown(*(int *)data, &mpipe->pipe_sigio); 1393 goto out_unlocked; 1394 1395 case FIOGETOWN: 1396 *(int *)data = fgetown(&mpipe->pipe_sigio); 1397 break; 1398 1399 /* This is deprecated, FIOSETOWN should be used instead. */ 1400 case TIOCSPGRP: 1401 PIPE_UNLOCK(mpipe); 1402 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio); 1403 goto out_unlocked; 1404 1405 /* This is deprecated, FIOGETOWN should be used instead. */ 1406 case TIOCGPGRP: 1407 *(int *)data = -fgetown(&mpipe->pipe_sigio); 1408 break; 1409 1410 default: 1411 error = ENOTTY; 1412 break; 1413 } 1414 PIPE_UNLOCK(mpipe); 1415 out_unlocked: 1416 return (error); 1417 } 1418 1419 static int 1420 pipe_poll(fp, events, active_cred, td) 1421 struct file *fp; 1422 int events; 1423 struct ucred *active_cred; 1424 struct thread *td; 1425 { 1426 struct pipe *rpipe; 1427 struct pipe *wpipe; 1428 int levents, revents; 1429 #ifdef MAC 1430 int error; 1431 #endif 1432 1433 revents = 0; 1434 rpipe = fp->f_data; 1435 wpipe = PIPE_PEER(rpipe); 1436 PIPE_LOCK(rpipe); 1437 #ifdef MAC 1438 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair); 1439 if (error) 1440 goto locked_error; 1441 #endif 1442 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) 1443 if ((rpipe->pipe_state & PIPE_DIRECTW) || 1444 (rpipe->pipe_buffer.cnt > 0)) 1445 revents |= events & (POLLIN | POLLRDNORM); 1446 1447 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) 1448 if (wpipe->pipe_present != PIPE_ACTIVE || 1449 (wpipe->pipe_state & PIPE_EOF) || 1450 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) && 1451 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF || 1452 wpipe->pipe_buffer.size == 0))) 1453 revents |= events & (POLLOUT | POLLWRNORM); 1454 1455 levents = events & 1456 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND); 1457 if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents && 1458 fp->f_seqcount == rpipe->pipe_wgen) 1459 events |= POLLINIGNEOF; 1460 1461 if ((events & POLLINIGNEOF) == 0) { 1462 if (rpipe->pipe_state & PIPE_EOF) { 1463 revents |= (events & (POLLIN | POLLRDNORM)); 1464 if (wpipe->pipe_present != PIPE_ACTIVE || 1465 (wpipe->pipe_state & PIPE_EOF)) 1466 revents |= POLLHUP; 1467 } 1468 } 1469 1470 if (revents == 0) { 1471 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) { 1472 selrecord(td, &rpipe->pipe_sel); 1473 if (SEL_WAITING(&rpipe->pipe_sel)) 1474 rpipe->pipe_state |= PIPE_SEL; 1475 } 1476 1477 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) { 1478 selrecord(td, &wpipe->pipe_sel); 1479 if (SEL_WAITING(&wpipe->pipe_sel)) 1480 wpipe->pipe_state |= PIPE_SEL; 1481 } 1482 } 1483 #ifdef MAC 1484 locked_error: 1485 #endif 1486 PIPE_UNLOCK(rpipe); 1487 1488 return (revents); 1489 } 1490 1491 /* 1492 * We shouldn't need locks here as we're doing a read and this should 1493 * be a natural race. 1494 */ 1495 static int 1496 pipe_stat(fp, ub, active_cred, td) 1497 struct file *fp; 1498 struct stat *ub; 1499 struct ucred *active_cred; 1500 struct thread *td; 1501 { 1502 struct pipe *pipe; 1503 int new_unr; 1504 #ifdef MAC 1505 int error; 1506 #endif 1507 1508 pipe = fp->f_data; 1509 PIPE_LOCK(pipe); 1510 #ifdef MAC 1511 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair); 1512 if (error) { 1513 PIPE_UNLOCK(pipe); 1514 return (error); 1515 } 1516 #endif 1517 1518 /* For named pipes ask the underlying filesystem. */ 1519 if (pipe->pipe_state & PIPE_NAMED) { 1520 PIPE_UNLOCK(pipe); 1521 return (vnops.fo_stat(fp, ub, active_cred, td)); 1522 } 1523 1524 /* 1525 * Lazily allocate an inode number for the pipe. Most pipe 1526 * users do not call fstat(2) on the pipe, which means that 1527 * postponing the inode allocation until it is must be 1528 * returned to userland is useful. If alloc_unr failed, 1529 * assign st_ino zero instead of returning an error. 1530 * Special pipe_ino values: 1531 * -1 - not yet initialized; 1532 * 0 - alloc_unr failed, return 0 as st_ino forever. 1533 */ 1534 if (pipe->pipe_ino == (ino_t)-1) { 1535 new_unr = alloc_unr(pipeino_unr); 1536 if (new_unr != -1) 1537 pipe->pipe_ino = new_unr; 1538 else 1539 pipe->pipe_ino = 0; 1540 } 1541 PIPE_UNLOCK(pipe); 1542 1543 bzero(ub, sizeof(*ub)); 1544 ub->st_mode = S_IFIFO; 1545 ub->st_blksize = PAGE_SIZE; 1546 if (pipe->pipe_state & PIPE_DIRECTW) 1547 ub->st_size = pipe->pipe_map.cnt; 1548 else 1549 ub->st_size = pipe->pipe_buffer.cnt; 1550 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize; 1551 ub->st_atim = pipe->pipe_atime; 1552 ub->st_mtim = pipe->pipe_mtime; 1553 ub->st_ctim = pipe->pipe_ctime; 1554 ub->st_uid = fp->f_cred->cr_uid; 1555 ub->st_gid = fp->f_cred->cr_gid; 1556 ub->st_dev = pipedev_ino; 1557 ub->st_ino = pipe->pipe_ino; 1558 /* 1559 * Left as 0: st_nlink, st_rdev, st_flags, st_gen. 1560 */ 1561 return (0); 1562 } 1563 1564 /* ARGSUSED */ 1565 static int 1566 pipe_close(fp, td) 1567 struct file *fp; 1568 struct thread *td; 1569 { 1570 1571 if (fp->f_vnode != NULL) 1572 return vnops.fo_close(fp, td); 1573 fp->f_ops = &badfileops; 1574 pipe_dtor(fp->f_data); 1575 fp->f_data = NULL; 1576 return (0); 1577 } 1578 1579 static int 1580 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td) 1581 { 1582 struct pipe *cpipe; 1583 int error; 1584 1585 cpipe = fp->f_data; 1586 if (cpipe->pipe_state & PIPE_NAMED) 1587 error = vn_chmod(fp, mode, active_cred, td); 1588 else 1589 error = invfo_chmod(fp, mode, active_cred, td); 1590 return (error); 1591 } 1592 1593 static int 1594 pipe_chown(fp, uid, gid, active_cred, td) 1595 struct file *fp; 1596 uid_t uid; 1597 gid_t gid; 1598 struct ucred *active_cred; 1599 struct thread *td; 1600 { 1601 struct pipe *cpipe; 1602 int error; 1603 1604 cpipe = fp->f_data; 1605 if (cpipe->pipe_state & PIPE_NAMED) 1606 error = vn_chown(fp, uid, gid, active_cred, td); 1607 else 1608 error = invfo_chown(fp, uid, gid, active_cred, td); 1609 return (error); 1610 } 1611 1612 static int 1613 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp) 1614 { 1615 struct pipe *pi; 1616 1617 if (fp->f_type == DTYPE_FIFO) 1618 return (vn_fill_kinfo(fp, kif, fdp)); 1619 kif->kf_type = KF_TYPE_PIPE; 1620 pi = fp->f_data; 1621 kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi; 1622 kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer; 1623 kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt; 1624 return (0); 1625 } 1626 1627 static void 1628 pipe_free_kmem(cpipe) 1629 struct pipe *cpipe; 1630 { 1631 1632 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), 1633 ("pipe_free_kmem: pipe mutex locked")); 1634 1635 if (cpipe->pipe_buffer.buffer != NULL) { 1636 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size); 1637 vm_map_remove(pipe_map, 1638 (vm_offset_t)cpipe->pipe_buffer.buffer, 1639 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size); 1640 cpipe->pipe_buffer.buffer = NULL; 1641 } 1642 #ifndef PIPE_NODIRECT 1643 { 1644 cpipe->pipe_map.cnt = 0; 1645 cpipe->pipe_map.pos = 0; 1646 cpipe->pipe_map.npages = 0; 1647 } 1648 #endif 1649 } 1650 1651 /* 1652 * shutdown the pipe 1653 */ 1654 static void 1655 pipeclose(cpipe) 1656 struct pipe *cpipe; 1657 { 1658 struct pipepair *pp; 1659 struct pipe *ppipe; 1660 1661 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL")); 1662 1663 PIPE_LOCK(cpipe); 1664 pipelock(cpipe, 0); 1665 pp = cpipe->pipe_pair; 1666 1667 pipeselwakeup(cpipe); 1668 1669 /* 1670 * If the other side is blocked, wake it up saying that 1671 * we want to close it down. 1672 */ 1673 cpipe->pipe_state |= PIPE_EOF; 1674 while (cpipe->pipe_busy) { 1675 wakeup(cpipe); 1676 cpipe->pipe_state |= PIPE_WANT; 1677 pipeunlock(cpipe); 1678 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0); 1679 pipelock(cpipe, 0); 1680 } 1681 1682 1683 /* 1684 * Disconnect from peer, if any. 1685 */ 1686 ppipe = cpipe->pipe_peer; 1687 if (ppipe->pipe_present == PIPE_ACTIVE) { 1688 pipeselwakeup(ppipe); 1689 1690 ppipe->pipe_state |= PIPE_EOF; 1691 wakeup(ppipe); 1692 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0); 1693 } 1694 1695 /* 1696 * Mark this endpoint as free. Release kmem resources. We 1697 * don't mark this endpoint as unused until we've finished 1698 * doing that, or the pipe might disappear out from under 1699 * us. 1700 */ 1701 PIPE_UNLOCK(cpipe); 1702 pipe_free_kmem(cpipe); 1703 PIPE_LOCK(cpipe); 1704 cpipe->pipe_present = PIPE_CLOSING; 1705 pipeunlock(cpipe); 1706 1707 /* 1708 * knlist_clear() may sleep dropping the PIPE_MTX. Set the 1709 * PIPE_FINALIZED, that allows other end to free the 1710 * pipe_pair, only after the knotes are completely dismantled. 1711 */ 1712 knlist_clear(&cpipe->pipe_sel.si_note, 1); 1713 cpipe->pipe_present = PIPE_FINALIZED; 1714 seldrain(&cpipe->pipe_sel); 1715 knlist_destroy(&cpipe->pipe_sel.si_note); 1716 1717 /* 1718 * If both endpoints are now closed, release the memory for the 1719 * pipe pair. If not, unlock. 1720 */ 1721 if (ppipe->pipe_present == PIPE_FINALIZED) { 1722 PIPE_UNLOCK(cpipe); 1723 #ifdef MAC 1724 mac_pipe_destroy(pp); 1725 #endif 1726 uma_zfree(pipe_zone, cpipe->pipe_pair); 1727 } else 1728 PIPE_UNLOCK(cpipe); 1729 } 1730 1731 /*ARGSUSED*/ 1732 static int 1733 pipe_kqfilter(struct file *fp, struct knote *kn) 1734 { 1735 struct pipe *cpipe; 1736 1737 /* 1738 * If a filter is requested that is not supported by this file 1739 * descriptor, don't return an error, but also don't ever generate an 1740 * event. 1741 */ 1742 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) { 1743 kn->kn_fop = &pipe_nfiltops; 1744 return (0); 1745 } 1746 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) { 1747 kn->kn_fop = &pipe_nfiltops; 1748 return (0); 1749 } 1750 cpipe = fp->f_data; 1751 PIPE_LOCK(cpipe); 1752 switch (kn->kn_filter) { 1753 case EVFILT_READ: 1754 kn->kn_fop = &pipe_rfiltops; 1755 break; 1756 case EVFILT_WRITE: 1757 kn->kn_fop = &pipe_wfiltops; 1758 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) { 1759 /* other end of pipe has been closed */ 1760 PIPE_UNLOCK(cpipe); 1761 return (EPIPE); 1762 } 1763 cpipe = PIPE_PEER(cpipe); 1764 break; 1765 default: 1766 PIPE_UNLOCK(cpipe); 1767 return (EINVAL); 1768 } 1769 1770 kn->kn_hook = cpipe; 1771 knlist_add(&cpipe->pipe_sel.si_note, kn, 1); 1772 PIPE_UNLOCK(cpipe); 1773 return (0); 1774 } 1775 1776 static void 1777 filt_pipedetach(struct knote *kn) 1778 { 1779 struct pipe *cpipe = kn->kn_hook; 1780 1781 PIPE_LOCK(cpipe); 1782 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1); 1783 PIPE_UNLOCK(cpipe); 1784 } 1785 1786 /*ARGSUSED*/ 1787 static int 1788 filt_piperead(struct knote *kn, long hint) 1789 { 1790 struct pipe *rpipe = kn->kn_hook; 1791 struct pipe *wpipe = rpipe->pipe_peer; 1792 int ret; 1793 1794 PIPE_LOCK_ASSERT(rpipe, MA_OWNED); 1795 kn->kn_data = rpipe->pipe_buffer.cnt; 1796 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) 1797 kn->kn_data = rpipe->pipe_map.cnt; 1798 1799 if ((rpipe->pipe_state & PIPE_EOF) || 1800 wpipe->pipe_present != PIPE_ACTIVE || 1801 (wpipe->pipe_state & PIPE_EOF)) { 1802 kn->kn_flags |= EV_EOF; 1803 return (1); 1804 } 1805 ret = kn->kn_data > 0; 1806 return ret; 1807 } 1808 1809 /*ARGSUSED*/ 1810 static int 1811 filt_pipewrite(struct knote *kn, long hint) 1812 { 1813 struct pipe *wpipe; 1814 1815 wpipe = kn->kn_hook; 1816 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 1817 if (wpipe->pipe_present != PIPE_ACTIVE || 1818 (wpipe->pipe_state & PIPE_EOF)) { 1819 kn->kn_data = 0; 1820 kn->kn_flags |= EV_EOF; 1821 return (1); 1822 } 1823 kn->kn_data = (wpipe->pipe_buffer.size > 0) ? 1824 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF; 1825 if (wpipe->pipe_state & PIPE_DIRECTW) 1826 kn->kn_data = 0; 1827 1828 return (kn->kn_data >= PIPE_BUF); 1829 } 1830 1831 static void 1832 filt_pipedetach_notsup(struct knote *kn) 1833 { 1834 1835 } 1836 1837 static int 1838 filt_pipenotsup(struct knote *kn, long hint) 1839 { 1840 1841 return (0); 1842 } 1843