Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/sys_pipe.c
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1 /*- 2 * Copyright (c) 1996 John S. Dyson 3 * Copyright (c) 2012 Giovanni Trematerra 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice immediately at the beginning of the file, without modification, 11 * this list of conditions, and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Absolutely no warranty of function or purpose is made by the author 16 * John S. Dyson. 17 * 4. Modifications may be freely made to this file if the above conditions 18 * are met. 19 */ 20 21 /* 22 * This file contains a high-performance replacement for the socket-based 23 * pipes scheme originally used in FreeBSD/4.4Lite. It does not support 24 * all features of sockets, but does do everything that pipes normally 25 * do. 26 */ 27 28 /* 29 * This code has two modes of operation, a small write mode and a large 30 * write mode. The small write mode acts like conventional pipes with 31 * a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the 32 * "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT 33 * and PIPE_SIZE in size, the sending process pins the underlying pages in 34 * memory, and the receiving process copies directly from these pinned pages 35 * in the sending process. 36 * 37 * If the sending process receives a signal, it is possible that it will 38 * go away, and certainly its address space can change, because control 39 * is returned back to the user-mode side. In that case, the pipe code 40 * arranges to copy the buffer supplied by the user process, to a pageable 41 * kernel buffer, and the receiving process will grab the data from the 42 * pageable kernel buffer. Since signals don't happen all that often, 43 * the copy operation is normally eliminated. 44 * 45 * The constant PIPE_MINDIRECT is chosen to make sure that buffering will 46 * happen for small transfers so that the system will not spend all of 47 * its time context switching. 48 * 49 * In order to limit the resource use of pipes, two sysctls exist: 50 * 51 * kern.ipc.maxpipekva - This is a hard limit on the amount of pageable 52 * address space available to us in pipe_map. This value is normally 53 * autotuned, but may also be loader tuned. 54 * 55 * kern.ipc.pipekva - This read-only sysctl tracks the current amount of 56 * memory in use by pipes. 57 * 58 * Based on how large pipekva is relative to maxpipekva, the following 59 * will happen: 60 * 61 * 0% - 50%: 62 * New pipes are given 16K of memory backing, pipes may dynamically 63 * grow to as large as 64K where needed. 64 * 50% - 75%: 65 * New pipes are given 4K (or PAGE_SIZE) of memory backing, 66 * existing pipes may NOT grow. 67 * 75% - 100%: 68 * New pipes are given 4K (or PAGE_SIZE) of memory backing, 69 * existing pipes will be shrunk down to 4K whenever possible. 70 * 71 * Resizing may be disabled by setting kern.ipc.piperesizeallowed=0. If 72 * that is set, the only resize that will occur is the 0 -> SMALL_PIPE_SIZE 73 * resize which MUST occur for reverse-direction pipes when they are 74 * first used. 75 * 76 * Additional information about the current state of pipes may be obtained 77 * from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail, 78 * and kern.ipc.piperesizefail. 79 * 80 * Locking rules: There are two locks present here: A mutex, used via 81 * PIPE_LOCK, and a flag, used via pipelock(). All locking is done via 82 * the flag, as mutexes can not persist over uiomove. The mutex 83 * exists only to guard access to the flag, and is not in itself a 84 * locking mechanism. Also note that there is only a single mutex for 85 * both directions of a pipe. 86 * 87 * As pipelock() may have to sleep before it can acquire the flag, it 88 * is important to reread all data after a call to pipelock(); everything 89 * in the structure may have changed. 90 */ 91 92 #include <sys/cdefs.h> 93 __FBSDID("$FreeBSD: releng/10.1/sys/kern/sys_pipe.c 268335 2014-07-06 22:47:18Z mjg $"); 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/event.h> 119 120 #include <security/mac/mac_framework.h> 121 122 #include <vm/vm.h> 123 #include <vm/vm_param.h> 124 #include <vm/vm_object.h> 125 #include <vm/vm_kern.h> 126 #include <vm/vm_extern.h> 127 #include <vm/pmap.h> 128 #include <vm/vm_map.h> 129 #include <vm/vm_page.h> 130 #include <vm/uma.h> 131 132 /* 133 * Use this define if you want to disable *fancy* VM things. Expect an 134 * approx 30% decrease in transfer rate. This could be useful for 135 * NetBSD or OpenBSD. 136 */ 137 /* #define PIPE_NODIRECT */ 138 139 #define PIPE_PEER(pipe) \ 140 (((pipe)->pipe_state & PIPE_NAMED) ? (pipe) : ((pipe)->pipe_peer)) 141 142 /* 143 * interfaces to the outside world 144 */ 145 static fo_rdwr_t pipe_read; 146 static fo_rdwr_t pipe_write; 147 static fo_truncate_t pipe_truncate; 148 static fo_ioctl_t pipe_ioctl; 149 static fo_poll_t pipe_poll; 150 static fo_kqfilter_t pipe_kqfilter; 151 static fo_stat_t pipe_stat; 152 static fo_close_t pipe_close; 153 static fo_chmod_t pipe_chmod; 154 static fo_chown_t pipe_chown; 155 156 struct fileops pipeops = { 157 .fo_read = pipe_read, 158 .fo_write = pipe_write, 159 .fo_truncate = pipe_truncate, 160 .fo_ioctl = pipe_ioctl, 161 .fo_poll = pipe_poll, 162 .fo_kqfilter = pipe_kqfilter, 163 .fo_stat = pipe_stat, 164 .fo_close = pipe_close, 165 .fo_chmod = pipe_chmod, 166 .fo_chown = pipe_chown, 167 .fo_sendfile = invfo_sendfile, 168 .fo_flags = DFLAG_PASSABLE 169 }; 170 171 static void filt_pipedetach(struct knote *kn); 172 static void filt_pipedetach_notsup(struct knote *kn); 173 static int filt_pipenotsup(struct knote *kn, long hint); 174 static int filt_piperead(struct knote *kn, long hint); 175 static int filt_pipewrite(struct knote *kn, long hint); 176 177 static struct filterops pipe_nfiltops = { 178 .f_isfd = 1, 179 .f_detach = filt_pipedetach_notsup, 180 .f_event = filt_pipenotsup 181 }; 182 static struct filterops pipe_rfiltops = { 183 .f_isfd = 1, 184 .f_detach = filt_pipedetach, 185 .f_event = filt_piperead 186 }; 187 static struct filterops pipe_wfiltops = { 188 .f_isfd = 1, 189 .f_detach = filt_pipedetach, 190 .f_event = filt_pipewrite 191 }; 192 193 /* 194 * Default pipe buffer size(s), this can be kind-of large now because pipe 195 * space is pageable. The pipe code will try to maintain locality of 196 * reference for performance reasons, so small amounts of outstanding I/O 197 * will not wipe the cache. 198 */ 199 #define MINPIPESIZE (PIPE_SIZE/3) 200 #define MAXPIPESIZE (2*PIPE_SIZE/3) 201 202 static long amountpipekva; 203 static int pipefragretry; 204 static int pipeallocfail; 205 static int piperesizefail; 206 static int piperesizeallowed = 1; 207 208 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN, 209 &maxpipekva, 0, "Pipe KVA limit"); 210 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD, 211 &amountpipekva, 0, "Pipe KVA usage"); 212 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD, 213 &pipefragretry, 0, "Pipe allocation retries due to fragmentation"); 214 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD, 215 &pipeallocfail, 0, "Pipe allocation failures"); 216 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD, 217 &piperesizefail, 0, "Pipe resize failures"); 218 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW, 219 &piperesizeallowed, 0, "Pipe resizing allowed"); 220 221 static void pipeinit(void *dummy __unused); 222 static void pipeclose(struct pipe *cpipe); 223 static void pipe_free_kmem(struct pipe *cpipe); 224 static void pipe_create(struct pipe *pipe, int backing); 225 static void pipe_paircreate(struct thread *td, struct pipepair **p_pp); 226 static __inline int pipelock(struct pipe *cpipe, int catch); 227 static __inline void pipeunlock(struct pipe *cpipe); 228 #ifndef PIPE_NODIRECT 229 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio); 230 static void pipe_destroy_write_buffer(struct pipe *wpipe); 231 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio); 232 static void pipe_clone_write_buffer(struct pipe *wpipe); 233 #endif 234 static int pipespace(struct pipe *cpipe, int size); 235 static int pipespace_new(struct pipe *cpipe, int size); 236 237 static int pipe_zone_ctor(void *mem, int size, void *arg, int flags); 238 static int pipe_zone_init(void *mem, int size, int flags); 239 static void pipe_zone_fini(void *mem, int size); 240 241 static uma_zone_t pipe_zone; 242 static struct unrhdr *pipeino_unr; 243 static dev_t pipedev_ino; 244 245 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL); 246 247 static void 248 pipeinit(void *dummy __unused) 249 { 250 251 pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair), 252 pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini, 253 UMA_ALIGN_PTR, 0); 254 KASSERT(pipe_zone != NULL, ("pipe_zone not initialized")); 255 pipeino_unr = new_unrhdr(1, INT32_MAX, NULL); 256 KASSERT(pipeino_unr != NULL, ("pipe fake inodes not initialized")); 257 pipedev_ino = devfs_alloc_cdp_inode(); 258 KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized")); 259 } 260 261 static int 262 pipe_zone_ctor(void *mem, int size, void *arg, int flags) 263 { 264 struct pipepair *pp; 265 struct pipe *rpipe, *wpipe; 266 267 KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size")); 268 269 pp = (struct pipepair *)mem; 270 271 /* 272 * We zero both pipe endpoints to make sure all the kmem pointers 273 * are NULL, flag fields are zero'd, etc. We timestamp both 274 * endpoints with the same time. 275 */ 276 rpipe = &pp->pp_rpipe; 277 bzero(rpipe, sizeof(*rpipe)); 278 vfs_timestamp(&rpipe->pipe_ctime); 279 rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime; 280 281 wpipe = &pp->pp_wpipe; 282 bzero(wpipe, sizeof(*wpipe)); 283 wpipe->pipe_ctime = rpipe->pipe_ctime; 284 wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime; 285 286 rpipe->pipe_peer = wpipe; 287 rpipe->pipe_pair = pp; 288 wpipe->pipe_peer = rpipe; 289 wpipe->pipe_pair = pp; 290 291 /* 292 * Mark both endpoints as present; they will later get free'd 293 * one at a time. When both are free'd, then the whole pair 294 * is released. 295 */ 296 rpipe->pipe_present = PIPE_ACTIVE; 297 wpipe->pipe_present = PIPE_ACTIVE; 298 299 /* 300 * Eventually, the MAC Framework may initialize the label 301 * in ctor or init, but for now we do it elswhere to avoid 302 * blocking in ctor or init. 303 */ 304 pp->pp_label = NULL; 305 306 return (0); 307 } 308 309 static int 310 pipe_zone_init(void *mem, int size, int flags) 311 { 312 struct pipepair *pp; 313 314 KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size")); 315 316 pp = (struct pipepair *)mem; 317 318 mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_RECURSE); 319 return (0); 320 } 321 322 static void 323 pipe_zone_fini(void *mem, int size) 324 { 325 struct pipepair *pp; 326 327 KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size")); 328 329 pp = (struct pipepair *)mem; 330 331 mtx_destroy(&pp->pp_mtx); 332 } 333 334 static void 335 pipe_paircreate(struct thread *td, struct pipepair **p_pp) 336 { 337 struct pipepair *pp; 338 struct pipe *rpipe, *wpipe; 339 340 *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK); 341 #ifdef MAC 342 /* 343 * The MAC label is shared between the connected endpoints. As a 344 * result mac_pipe_init() and mac_pipe_create() are called once 345 * for the pair, and not on the endpoints. 346 */ 347 mac_pipe_init(pp); 348 mac_pipe_create(td->td_ucred, pp); 349 #endif 350 rpipe = &pp->pp_rpipe; 351 wpipe = &pp->pp_wpipe; 352 353 knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe)); 354 knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe)); 355 356 /* Only the forward direction pipe is backed by default */ 357 pipe_create(rpipe, 1); 358 pipe_create(wpipe, 0); 359 360 rpipe->pipe_state |= PIPE_DIRECTOK; 361 wpipe->pipe_state |= PIPE_DIRECTOK; 362 } 363 364 void 365 pipe_named_ctor(struct pipe **ppipe, struct thread *td) 366 { 367 struct pipepair *pp; 368 369 pipe_paircreate(td, &pp); 370 pp->pp_rpipe.pipe_state |= PIPE_NAMED; 371 *ppipe = &pp->pp_rpipe; 372 } 373 374 void 375 pipe_dtor(struct pipe *dpipe) 376 { 377 ino_t ino; 378 379 ino = dpipe->pipe_ino; 380 funsetown(&dpipe->pipe_sigio); 381 pipeclose(dpipe); 382 if (dpipe->pipe_state & PIPE_NAMED) { 383 dpipe = dpipe->pipe_peer; 384 funsetown(&dpipe->pipe_sigio); 385 pipeclose(dpipe); 386 } 387 if (ino != 0 && ino != (ino_t)-1) 388 free_unr(pipeino_unr, ino); 389 } 390 391 /* 392 * The pipe system call for the DTYPE_PIPE type of pipes. If we fail, let 393 * the zone pick up the pieces via pipeclose(). 394 */ 395 int 396 kern_pipe(struct thread *td, int fildes[2]) 397 { 398 399 return (kern_pipe2(td, fildes, 0)); 400 } 401 402 int 403 kern_pipe2(struct thread *td, int fildes[2], int flags) 404 { 405 struct filedesc *fdp; 406 struct file *rf, *wf; 407 struct pipe *rpipe, *wpipe; 408 struct pipepair *pp; 409 int fd, fflags, error; 410 411 fdp = td->td_proc->p_fd; 412 pipe_paircreate(td, &pp); 413 rpipe = &pp->pp_rpipe; 414 wpipe = &pp->pp_wpipe; 415 error = falloc(td, &rf, &fd, flags); 416 if (error) { 417 pipeclose(rpipe); 418 pipeclose(wpipe); 419 return (error); 420 } 421 /* An extra reference on `rf' has been held for us by falloc(). */ 422 fildes[0] = fd; 423 424 fflags = FREAD | FWRITE; 425 if ((flags & O_NONBLOCK) != 0) 426 fflags |= FNONBLOCK; 427 428 /* 429 * Warning: once we've gotten past allocation of the fd for the 430 * read-side, we can only drop the read side via fdrop() in order 431 * to avoid races against processes which manage to dup() the read 432 * side while we are blocked trying to allocate the write side. 433 */ 434 finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops); 435 error = falloc(td, &wf, &fd, flags); 436 if (error) { 437 fdclose(fdp, rf, fildes[0], td); 438 fdrop(rf, td); 439 /* rpipe has been closed by fdrop(). */ 440 pipeclose(wpipe); 441 return (error); 442 } 443 /* An extra reference on `wf' has been held for us by falloc(). */ 444 finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops); 445 fdrop(wf, td); 446 fildes[1] = fd; 447 fdrop(rf, td); 448 449 return (0); 450 } 451 452 /* ARGSUSED */ 453 int 454 sys_pipe(struct thread *td, struct pipe_args *uap) 455 { 456 int error; 457 int fildes[2]; 458 459 error = kern_pipe(td, fildes); 460 if (error) 461 return (error); 462 463 td->td_retval[0] = fildes[0]; 464 td->td_retval[1] = fildes[1]; 465 466 return (0); 467 } 468 469 int 470 sys_pipe2(struct thread *td, struct pipe2_args *uap) 471 { 472 int error, fildes[2]; 473 474 if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK)) 475 return (EINVAL); 476 error = kern_pipe2(td, fildes, uap->flags); 477 if (error) 478 return (error); 479 error = copyout(fildes, uap->fildes, 2 * sizeof(int)); 480 if (error) { 481 (void)kern_close(td, fildes[0]); 482 (void)kern_close(td, fildes[1]); 483 } 484 return (error); 485 } 486 487 /* 488 * Allocate kva for pipe circular buffer, the space is pageable 489 * This routine will 'realloc' the size of a pipe safely, if it fails 490 * it will retain the old buffer. 491 * If it fails it will return ENOMEM. 492 */ 493 static int 494 pipespace_new(cpipe, size) 495 struct pipe *cpipe; 496 int size; 497 { 498 caddr_t buffer; 499 int error, cnt, firstseg; 500 static int curfail = 0; 501 static struct timeval lastfail; 502 503 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked")); 504 KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW), 505 ("pipespace: resize of direct writes not allowed")); 506 retry: 507 cnt = cpipe->pipe_buffer.cnt; 508 if (cnt > size) 509 size = cnt; 510 511 size = round_page(size); 512 buffer = (caddr_t) vm_map_min(pipe_map); 513 514 error = vm_map_find(pipe_map, NULL, 0, 515 (vm_offset_t *) &buffer, size, 0, VMFS_ANY_SPACE, 516 VM_PROT_ALL, VM_PROT_ALL, 0); 517 if (error != KERN_SUCCESS) { 518 if ((cpipe->pipe_buffer.buffer == NULL) && 519 (size > SMALL_PIPE_SIZE)) { 520 size = SMALL_PIPE_SIZE; 521 pipefragretry++; 522 goto retry; 523 } 524 if (cpipe->pipe_buffer.buffer == NULL) { 525 pipeallocfail++; 526 if (ppsratecheck(&lastfail, &curfail, 1)) 527 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n"); 528 } else { 529 piperesizefail++; 530 } 531 return (ENOMEM); 532 } 533 534 /* copy data, then free old resources if we're resizing */ 535 if (cnt > 0) { 536 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) { 537 firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out; 538 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 539 buffer, firstseg); 540 if ((cnt - firstseg) > 0) 541 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg], 542 cpipe->pipe_buffer.in); 543 } else { 544 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 545 buffer, cnt); 546 } 547 } 548 pipe_free_kmem(cpipe); 549 cpipe->pipe_buffer.buffer = buffer; 550 cpipe->pipe_buffer.size = size; 551 cpipe->pipe_buffer.in = cnt; 552 cpipe->pipe_buffer.out = 0; 553 cpipe->pipe_buffer.cnt = cnt; 554 atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size); 555 return (0); 556 } 557 558 /* 559 * Wrapper for pipespace_new() that performs locking assertions. 560 */ 561 static int 562 pipespace(cpipe, size) 563 struct pipe *cpipe; 564 int size; 565 { 566 567 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 568 ("Unlocked pipe passed to pipespace")); 569 return (pipespace_new(cpipe, size)); 570 } 571 572 /* 573 * lock a pipe for I/O, blocking other access 574 */ 575 static __inline int 576 pipelock(cpipe, catch) 577 struct pipe *cpipe; 578 int catch; 579 { 580 int error; 581 582 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 583 while (cpipe->pipe_state & PIPE_LOCKFL) { 584 cpipe->pipe_state |= PIPE_LWANT; 585 error = msleep(cpipe, PIPE_MTX(cpipe), 586 catch ? (PRIBIO | PCATCH) : PRIBIO, 587 "pipelk", 0); 588 if (error != 0) 589 return (error); 590 } 591 cpipe->pipe_state |= PIPE_LOCKFL; 592 return (0); 593 } 594 595 /* 596 * unlock a pipe I/O lock 597 */ 598 static __inline void 599 pipeunlock(cpipe) 600 struct pipe *cpipe; 601 { 602 603 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 604 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 605 ("Unlocked pipe passed to pipeunlock")); 606 cpipe->pipe_state &= ~PIPE_LOCKFL; 607 if (cpipe->pipe_state & PIPE_LWANT) { 608 cpipe->pipe_state &= ~PIPE_LWANT; 609 wakeup(cpipe); 610 } 611 } 612 613 void 614 pipeselwakeup(cpipe) 615 struct pipe *cpipe; 616 { 617 618 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 619 if (cpipe->pipe_state & PIPE_SEL) { 620 selwakeuppri(&cpipe->pipe_sel, PSOCK); 621 if (!SEL_WAITING(&cpipe->pipe_sel)) 622 cpipe->pipe_state &= ~PIPE_SEL; 623 } 624 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) 625 pgsigio(&cpipe->pipe_sigio, SIGIO, 0); 626 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0); 627 } 628 629 /* 630 * Initialize and allocate VM and memory for pipe. The structure 631 * will start out zero'd from the ctor, so we just manage the kmem. 632 */ 633 static void 634 pipe_create(pipe, backing) 635 struct pipe *pipe; 636 int backing; 637 { 638 639 if (backing) { 640 /* 641 * Note that these functions can fail if pipe map is exhausted 642 * (as a result of too many pipes created), but we ignore the 643 * error as it is not fatal and could be provoked by 644 * unprivileged users. The only consequence is worse performance 645 * with given pipe. 646 */ 647 if (amountpipekva > maxpipekva / 2) 648 (void)pipespace_new(pipe, SMALL_PIPE_SIZE); 649 else 650 (void)pipespace_new(pipe, PIPE_SIZE); 651 } 652 653 pipe->pipe_ino = -1; 654 } 655 656 /* ARGSUSED */ 657 static int 658 pipe_read(fp, uio, active_cred, flags, td) 659 struct file *fp; 660 struct uio *uio; 661 struct ucred *active_cred; 662 struct thread *td; 663 int flags; 664 { 665 struct pipe *rpipe; 666 int error; 667 int nread = 0; 668 int size; 669 670 rpipe = fp->f_data; 671 PIPE_LOCK(rpipe); 672 ++rpipe->pipe_busy; 673 error = pipelock(rpipe, 1); 674 if (error) 675 goto unlocked_error; 676 677 #ifdef MAC 678 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair); 679 if (error) 680 goto locked_error; 681 #endif 682 if (amountpipekva > (3 * maxpipekva) / 4) { 683 if (!(rpipe->pipe_state & PIPE_DIRECTW) && 684 (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) && 685 (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) && 686 (piperesizeallowed == 1)) { 687 PIPE_UNLOCK(rpipe); 688 pipespace(rpipe, SMALL_PIPE_SIZE); 689 PIPE_LOCK(rpipe); 690 } 691 } 692 693 while (uio->uio_resid) { 694 /* 695 * normal pipe buffer receive 696 */ 697 if (rpipe->pipe_buffer.cnt > 0) { 698 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 699 if (size > rpipe->pipe_buffer.cnt) 700 size = rpipe->pipe_buffer.cnt; 701 if (size > uio->uio_resid) 702 size = uio->uio_resid; 703 704 PIPE_UNLOCK(rpipe); 705 error = uiomove( 706 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 707 size, uio); 708 PIPE_LOCK(rpipe); 709 if (error) 710 break; 711 712 rpipe->pipe_buffer.out += size; 713 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 714 rpipe->pipe_buffer.out = 0; 715 716 rpipe->pipe_buffer.cnt -= size; 717 718 /* 719 * If there is no more to read in the pipe, reset 720 * its pointers to the beginning. This improves 721 * cache hit stats. 722 */ 723 if (rpipe->pipe_buffer.cnt == 0) { 724 rpipe->pipe_buffer.in = 0; 725 rpipe->pipe_buffer.out = 0; 726 } 727 nread += size; 728 #ifndef PIPE_NODIRECT 729 /* 730 * Direct copy, bypassing a kernel buffer. 731 */ 732 } else if ((size = rpipe->pipe_map.cnt) && 733 (rpipe->pipe_state & PIPE_DIRECTW)) { 734 if (size > uio->uio_resid) 735 size = (u_int) uio->uio_resid; 736 737 PIPE_UNLOCK(rpipe); 738 error = uiomove_fromphys(rpipe->pipe_map.ms, 739 rpipe->pipe_map.pos, size, uio); 740 PIPE_LOCK(rpipe); 741 if (error) 742 break; 743 nread += size; 744 rpipe->pipe_map.pos += size; 745 rpipe->pipe_map.cnt -= size; 746 if (rpipe->pipe_map.cnt == 0) { 747 rpipe->pipe_state &= ~(PIPE_DIRECTW|PIPE_WANTW); 748 wakeup(rpipe); 749 } 750 #endif 751 } else { 752 /* 753 * detect EOF condition 754 * read returns 0 on EOF, no need to set error 755 */ 756 if (rpipe->pipe_state & PIPE_EOF) 757 break; 758 759 /* 760 * If the "write-side" has been blocked, wake it up now. 761 */ 762 if (rpipe->pipe_state & PIPE_WANTW) { 763 rpipe->pipe_state &= ~PIPE_WANTW; 764 wakeup(rpipe); 765 } 766 767 /* 768 * Break if some data was read. 769 */ 770 if (nread > 0) 771 break; 772 773 /* 774 * Unlock the pipe buffer for our remaining processing. 775 * We will either break out with an error or we will 776 * sleep and relock to loop. 777 */ 778 pipeunlock(rpipe); 779 780 /* 781 * Handle non-blocking mode operation or 782 * wait for more data. 783 */ 784 if (fp->f_flag & FNONBLOCK) { 785 error = EAGAIN; 786 } else { 787 rpipe->pipe_state |= PIPE_WANTR; 788 if ((error = msleep(rpipe, PIPE_MTX(rpipe), 789 PRIBIO | PCATCH, 790 "piperd", 0)) == 0) 791 error = pipelock(rpipe, 1); 792 } 793 if (error) 794 goto unlocked_error; 795 } 796 } 797 #ifdef MAC 798 locked_error: 799 #endif 800 pipeunlock(rpipe); 801 802 /* XXX: should probably do this before getting any locks. */ 803 if (error == 0) 804 vfs_timestamp(&rpipe->pipe_atime); 805 unlocked_error: 806 --rpipe->pipe_busy; 807 808 /* 809 * PIPE_WANT processing only makes sense if pipe_busy is 0. 810 */ 811 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 812 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 813 wakeup(rpipe); 814 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 815 /* 816 * Handle write blocking hysteresis. 817 */ 818 if (rpipe->pipe_state & PIPE_WANTW) { 819 rpipe->pipe_state &= ~PIPE_WANTW; 820 wakeup(rpipe); 821 } 822 } 823 824 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF) 825 pipeselwakeup(rpipe); 826 827 PIPE_UNLOCK(rpipe); 828 return (error); 829 } 830 831 #ifndef PIPE_NODIRECT 832 /* 833 * Map the sending processes' buffer into kernel space and wire it. 834 * This is similar to a physical write operation. 835 */ 836 static int 837 pipe_build_write_buffer(wpipe, uio) 838 struct pipe *wpipe; 839 struct uio *uio; 840 { 841 u_int size; 842 int i; 843 844 PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED); 845 KASSERT(wpipe->pipe_state & PIPE_DIRECTW, 846 ("Clone attempt on non-direct write pipe!")); 847 848 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size) 849 size = wpipe->pipe_buffer.size; 850 else 851 size = uio->uio_iov->iov_len; 852 853 if ((i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 854 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ, 855 wpipe->pipe_map.ms, PIPENPAGES)) < 0) 856 return (EFAULT); 857 858 /* 859 * set up the control block 860 */ 861 wpipe->pipe_map.npages = i; 862 wpipe->pipe_map.pos = 863 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 864 wpipe->pipe_map.cnt = size; 865 866 /* 867 * and update the uio data 868 */ 869 870 uio->uio_iov->iov_len -= size; 871 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size; 872 if (uio->uio_iov->iov_len == 0) 873 uio->uio_iov++; 874 uio->uio_resid -= size; 875 uio->uio_offset += size; 876 return (0); 877 } 878 879 /* 880 * unmap and unwire the process buffer 881 */ 882 static void 883 pipe_destroy_write_buffer(wpipe) 884 struct pipe *wpipe; 885 { 886 887 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 888 vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages); 889 wpipe->pipe_map.npages = 0; 890 } 891 892 /* 893 * In the case of a signal, the writing process might go away. This 894 * code copies the data into the circular buffer so that the source 895 * pages can be freed without loss of data. 896 */ 897 static void 898 pipe_clone_write_buffer(wpipe) 899 struct pipe *wpipe; 900 { 901 struct uio uio; 902 struct iovec iov; 903 int size; 904 int pos; 905 906 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 907 size = wpipe->pipe_map.cnt; 908 pos = wpipe->pipe_map.pos; 909 910 wpipe->pipe_buffer.in = size; 911 wpipe->pipe_buffer.out = 0; 912 wpipe->pipe_buffer.cnt = size; 913 wpipe->pipe_state &= ~PIPE_DIRECTW; 914 915 PIPE_UNLOCK(wpipe); 916 iov.iov_base = wpipe->pipe_buffer.buffer; 917 iov.iov_len = size; 918 uio.uio_iov = &iov; 919 uio.uio_iovcnt = 1; 920 uio.uio_offset = 0; 921 uio.uio_resid = size; 922 uio.uio_segflg = UIO_SYSSPACE; 923 uio.uio_rw = UIO_READ; 924 uio.uio_td = curthread; 925 uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio); 926 PIPE_LOCK(wpipe); 927 pipe_destroy_write_buffer(wpipe); 928 } 929 930 /* 931 * This implements the pipe buffer write mechanism. Note that only 932 * a direct write OR a normal pipe write can be pending at any given time. 933 * If there are any characters in the pipe buffer, the direct write will 934 * be deferred until the receiving process grabs all of the bytes from 935 * the pipe buffer. Then the direct mapping write is set-up. 936 */ 937 static int 938 pipe_direct_write(wpipe, uio) 939 struct pipe *wpipe; 940 struct uio *uio; 941 { 942 int error; 943 944 retry: 945 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 946 error = pipelock(wpipe, 1); 947 if (wpipe->pipe_state & PIPE_EOF) 948 error = EPIPE; 949 if (error) { 950 pipeunlock(wpipe); 951 goto error1; 952 } 953 while (wpipe->pipe_state & PIPE_DIRECTW) { 954 if (wpipe->pipe_state & PIPE_WANTR) { 955 wpipe->pipe_state &= ~PIPE_WANTR; 956 wakeup(wpipe); 957 } 958 pipeselwakeup(wpipe); 959 wpipe->pipe_state |= PIPE_WANTW; 960 pipeunlock(wpipe); 961 error = msleep(wpipe, PIPE_MTX(wpipe), 962 PRIBIO | PCATCH, "pipdww", 0); 963 if (error) 964 goto error1; 965 else 966 goto retry; 967 } 968 wpipe->pipe_map.cnt = 0; /* transfer not ready yet */ 969 if (wpipe->pipe_buffer.cnt > 0) { 970 if (wpipe->pipe_state & PIPE_WANTR) { 971 wpipe->pipe_state &= ~PIPE_WANTR; 972 wakeup(wpipe); 973 } 974 pipeselwakeup(wpipe); 975 wpipe->pipe_state |= PIPE_WANTW; 976 pipeunlock(wpipe); 977 error = msleep(wpipe, PIPE_MTX(wpipe), 978 PRIBIO | PCATCH, "pipdwc", 0); 979 if (error) 980 goto error1; 981 else 982 goto retry; 983 } 984 985 wpipe->pipe_state |= PIPE_DIRECTW; 986 987 PIPE_UNLOCK(wpipe); 988 error = pipe_build_write_buffer(wpipe, uio); 989 PIPE_LOCK(wpipe); 990 if (error) { 991 wpipe->pipe_state &= ~PIPE_DIRECTW; 992 pipeunlock(wpipe); 993 goto error1; 994 } 995 996 error = 0; 997 while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) { 998 if (wpipe->pipe_state & PIPE_EOF) { 999 pipe_destroy_write_buffer(wpipe); 1000 pipeselwakeup(wpipe); 1001 pipeunlock(wpipe); 1002 error = EPIPE; 1003 goto error1; 1004 } 1005 if (wpipe->pipe_state & PIPE_WANTR) { 1006 wpipe->pipe_state &= ~PIPE_WANTR; 1007 wakeup(wpipe); 1008 } 1009 pipeselwakeup(wpipe); 1010 wpipe->pipe_state |= PIPE_WANTW; 1011 pipeunlock(wpipe); 1012 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH, 1013 "pipdwt", 0); 1014 pipelock(wpipe, 0); 1015 } 1016 1017 if (wpipe->pipe_state & PIPE_EOF) 1018 error = EPIPE; 1019 if (wpipe->pipe_state & PIPE_DIRECTW) { 1020 /* 1021 * this bit of trickery substitutes a kernel buffer for 1022 * the process that might be going away. 1023 */ 1024 pipe_clone_write_buffer(wpipe); 1025 } else { 1026 pipe_destroy_write_buffer(wpipe); 1027 } 1028 pipeunlock(wpipe); 1029 return (error); 1030 1031 error1: 1032 wakeup(wpipe); 1033 return (error); 1034 } 1035 #endif 1036 1037 static int 1038 pipe_write(fp, uio, active_cred, flags, td) 1039 struct file *fp; 1040 struct uio *uio; 1041 struct ucred *active_cred; 1042 struct thread *td; 1043 int flags; 1044 { 1045 int error = 0; 1046 int desiredsize; 1047 ssize_t orig_resid; 1048 struct pipe *wpipe, *rpipe; 1049 1050 rpipe = fp->f_data; 1051 wpipe = PIPE_PEER(rpipe); 1052 PIPE_LOCK(rpipe); 1053 error = pipelock(wpipe, 1); 1054 if (error) { 1055 PIPE_UNLOCK(rpipe); 1056 return (error); 1057 } 1058 /* 1059 * detect loss of pipe read side, issue SIGPIPE if lost. 1060 */ 1061 if (wpipe->pipe_present != PIPE_ACTIVE || 1062 (wpipe->pipe_state & PIPE_EOF)) { 1063 pipeunlock(wpipe); 1064 PIPE_UNLOCK(rpipe); 1065 return (EPIPE); 1066 } 1067 #ifdef MAC 1068 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair); 1069 if (error) { 1070 pipeunlock(wpipe); 1071 PIPE_UNLOCK(rpipe); 1072 return (error); 1073 } 1074 #endif 1075 ++wpipe->pipe_busy; 1076 1077 /* Choose a larger size if it's advantageous */ 1078 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size); 1079 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) { 1080 if (piperesizeallowed != 1) 1081 break; 1082 if (amountpipekva > maxpipekva / 2) 1083 break; 1084 if (desiredsize == BIG_PIPE_SIZE) 1085 break; 1086 desiredsize = desiredsize * 2; 1087 } 1088 1089 /* Choose a smaller size if we're in a OOM situation */ 1090 if ((amountpipekva > (3 * maxpipekva) / 4) && 1091 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) && 1092 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) && 1093 (piperesizeallowed == 1)) 1094 desiredsize = SMALL_PIPE_SIZE; 1095 1096 /* Resize if the above determined that a new size was necessary */ 1097 if ((desiredsize != wpipe->pipe_buffer.size) && 1098 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) { 1099 PIPE_UNLOCK(wpipe); 1100 pipespace(wpipe, desiredsize); 1101 PIPE_LOCK(wpipe); 1102 } 1103 if (wpipe->pipe_buffer.size == 0) { 1104 /* 1105 * This can only happen for reverse direction use of pipes 1106 * in a complete OOM situation. 1107 */ 1108 error = ENOMEM; 1109 --wpipe->pipe_busy; 1110 pipeunlock(wpipe); 1111 PIPE_UNLOCK(wpipe); 1112 return (error); 1113 } 1114 1115 pipeunlock(wpipe); 1116 1117 orig_resid = uio->uio_resid; 1118 1119 while (uio->uio_resid) { 1120 int space; 1121 1122 pipelock(wpipe, 0); 1123 if (wpipe->pipe_state & PIPE_EOF) { 1124 pipeunlock(wpipe); 1125 error = EPIPE; 1126 break; 1127 } 1128 #ifndef PIPE_NODIRECT 1129 /* 1130 * If the transfer is large, we can gain performance if 1131 * we do process-to-process copies directly. 1132 * If the write is non-blocking, we don't use the 1133 * direct write mechanism. 1134 * 1135 * The direct write mechanism will detect the reader going 1136 * away on us. 1137 */ 1138 if (uio->uio_segflg == UIO_USERSPACE && 1139 uio->uio_iov->iov_len >= PIPE_MINDIRECT && 1140 wpipe->pipe_buffer.size >= PIPE_MINDIRECT && 1141 (fp->f_flag & FNONBLOCK) == 0) { 1142 pipeunlock(wpipe); 1143 error = pipe_direct_write(wpipe, uio); 1144 if (error) 1145 break; 1146 continue; 1147 } 1148 #endif 1149 1150 /* 1151 * Pipe buffered writes cannot be coincidental with 1152 * direct writes. We wait until the currently executing 1153 * direct write is completed before we start filling the 1154 * pipe buffer. We break out if a signal occurs or the 1155 * reader goes away. 1156 */ 1157 if (wpipe->pipe_state & PIPE_DIRECTW) { 1158 if (wpipe->pipe_state & PIPE_WANTR) { 1159 wpipe->pipe_state &= ~PIPE_WANTR; 1160 wakeup(wpipe); 1161 } 1162 pipeselwakeup(wpipe); 1163 wpipe->pipe_state |= PIPE_WANTW; 1164 pipeunlock(wpipe); 1165 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH, 1166 "pipbww", 0); 1167 if (error) 1168 break; 1169 else 1170 continue; 1171 } 1172 1173 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1174 1175 /* Writes of size <= PIPE_BUF must be atomic. */ 1176 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 1177 space = 0; 1178 1179 if (space > 0) { 1180 int size; /* Transfer size */ 1181 int segsize; /* first segment to transfer */ 1182 1183 /* 1184 * Transfer size is minimum of uio transfer 1185 * and free space in pipe buffer. 1186 */ 1187 if (space > uio->uio_resid) 1188 size = uio->uio_resid; 1189 else 1190 size = space; 1191 /* 1192 * First segment to transfer is minimum of 1193 * transfer size and contiguous space in 1194 * pipe buffer. If first segment to transfer 1195 * is less than the transfer size, we've got 1196 * a wraparound in the buffer. 1197 */ 1198 segsize = wpipe->pipe_buffer.size - 1199 wpipe->pipe_buffer.in; 1200 if (segsize > size) 1201 segsize = size; 1202 1203 /* Transfer first segment */ 1204 1205 PIPE_UNLOCK(rpipe); 1206 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 1207 segsize, uio); 1208 PIPE_LOCK(rpipe); 1209 1210 if (error == 0 && segsize < size) { 1211 KASSERT(wpipe->pipe_buffer.in + segsize == 1212 wpipe->pipe_buffer.size, 1213 ("Pipe buffer wraparound disappeared")); 1214 /* 1215 * Transfer remaining part now, to 1216 * support atomic writes. Wraparound 1217 * happened. 1218 */ 1219 1220 PIPE_UNLOCK(rpipe); 1221 error = uiomove( 1222 &wpipe->pipe_buffer.buffer[0], 1223 size - segsize, uio); 1224 PIPE_LOCK(rpipe); 1225 } 1226 if (error == 0) { 1227 wpipe->pipe_buffer.in += size; 1228 if (wpipe->pipe_buffer.in >= 1229 wpipe->pipe_buffer.size) { 1230 KASSERT(wpipe->pipe_buffer.in == 1231 size - segsize + 1232 wpipe->pipe_buffer.size, 1233 ("Expected wraparound bad")); 1234 wpipe->pipe_buffer.in = size - segsize; 1235 } 1236 1237 wpipe->pipe_buffer.cnt += size; 1238 KASSERT(wpipe->pipe_buffer.cnt <= 1239 wpipe->pipe_buffer.size, 1240 ("Pipe buffer overflow")); 1241 } 1242 pipeunlock(wpipe); 1243 if (error != 0) 1244 break; 1245 } else { 1246 /* 1247 * If the "read-side" has been blocked, wake it up now. 1248 */ 1249 if (wpipe->pipe_state & PIPE_WANTR) { 1250 wpipe->pipe_state &= ~PIPE_WANTR; 1251 wakeup(wpipe); 1252 } 1253 1254 /* 1255 * don't block on non-blocking I/O 1256 */ 1257 if (fp->f_flag & FNONBLOCK) { 1258 error = EAGAIN; 1259 pipeunlock(wpipe); 1260 break; 1261 } 1262 1263 /* 1264 * We have no more space and have something to offer, 1265 * wake up select/poll. 1266 */ 1267 pipeselwakeup(wpipe); 1268 1269 wpipe->pipe_state |= PIPE_WANTW; 1270 pipeunlock(wpipe); 1271 error = msleep(wpipe, PIPE_MTX(rpipe), 1272 PRIBIO | PCATCH, "pipewr", 0); 1273 if (error != 0) 1274 break; 1275 } 1276 } 1277 1278 pipelock(wpipe, 0); 1279 --wpipe->pipe_busy; 1280 1281 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 1282 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 1283 wakeup(wpipe); 1284 } else if (wpipe->pipe_buffer.cnt > 0) { 1285 /* 1286 * If we have put any characters in the buffer, we wake up 1287 * the reader. 1288 */ 1289 if (wpipe->pipe_state & PIPE_WANTR) { 1290 wpipe->pipe_state &= ~PIPE_WANTR; 1291 wakeup(wpipe); 1292 } 1293 } 1294 1295 /* 1296 * Don't return EPIPE if I/O was successful 1297 */ 1298 if ((wpipe->pipe_buffer.cnt == 0) && 1299 (uio->uio_resid == 0) && 1300 (error == EPIPE)) { 1301 error = 0; 1302 } 1303 1304 if (error == 0) 1305 vfs_timestamp(&wpipe->pipe_mtime); 1306 1307 /* 1308 * We have something to offer, 1309 * wake up select/poll. 1310 */ 1311 if (wpipe->pipe_buffer.cnt) 1312 pipeselwakeup(wpipe); 1313 1314 pipeunlock(wpipe); 1315 PIPE_UNLOCK(rpipe); 1316 return (error); 1317 } 1318 1319 /* ARGSUSED */ 1320 static int 1321 pipe_truncate(fp, length, active_cred, td) 1322 struct file *fp; 1323 off_t length; 1324 struct ucred *active_cred; 1325 struct thread *td; 1326 { 1327 1328 /* For named pipes call the vnode operation. */ 1329 if (fp->f_vnode != NULL) 1330 return (vnops.fo_truncate(fp, length, active_cred, td)); 1331 return (EINVAL); 1332 } 1333 1334 /* 1335 * we implement a very minimal set of ioctls for compatibility with sockets. 1336 */ 1337 static int 1338 pipe_ioctl(fp, cmd, data, active_cred, td) 1339 struct file *fp; 1340 u_long cmd; 1341 void *data; 1342 struct ucred *active_cred; 1343 struct thread *td; 1344 { 1345 struct pipe *mpipe = fp->f_data; 1346 int error; 1347 1348 PIPE_LOCK(mpipe); 1349 1350 #ifdef MAC 1351 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data); 1352 if (error) { 1353 PIPE_UNLOCK(mpipe); 1354 return (error); 1355 } 1356 #endif 1357 1358 error = 0; 1359 switch (cmd) { 1360 1361 case FIONBIO: 1362 break; 1363 1364 case FIOASYNC: 1365 if (*(int *)data) { 1366 mpipe->pipe_state |= PIPE_ASYNC; 1367 } else { 1368 mpipe->pipe_state &= ~PIPE_ASYNC; 1369 } 1370 break; 1371 1372 case FIONREAD: 1373 if (!(fp->f_flag & FREAD)) { 1374 *(int *)data = 0; 1375 PIPE_UNLOCK(mpipe); 1376 return (0); 1377 } 1378 if (mpipe->pipe_state & PIPE_DIRECTW) 1379 *(int *)data = mpipe->pipe_map.cnt; 1380 else 1381 *(int *)data = mpipe->pipe_buffer.cnt; 1382 break; 1383 1384 case FIOSETOWN: 1385 PIPE_UNLOCK(mpipe); 1386 error = fsetown(*(int *)data, &mpipe->pipe_sigio); 1387 goto out_unlocked; 1388 1389 case FIOGETOWN: 1390 *(int *)data = fgetown(&mpipe->pipe_sigio); 1391 break; 1392 1393 /* This is deprecated, FIOSETOWN should be used instead. */ 1394 case TIOCSPGRP: 1395 PIPE_UNLOCK(mpipe); 1396 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio); 1397 goto out_unlocked; 1398 1399 /* This is deprecated, FIOGETOWN should be used instead. */ 1400 case TIOCGPGRP: 1401 *(int *)data = -fgetown(&mpipe->pipe_sigio); 1402 break; 1403 1404 default: 1405 error = ENOTTY; 1406 break; 1407 } 1408 PIPE_UNLOCK(mpipe); 1409 out_unlocked: 1410 return (error); 1411 } 1412 1413 static int 1414 pipe_poll(fp, events, active_cred, td) 1415 struct file *fp; 1416 int events; 1417 struct ucred *active_cred; 1418 struct thread *td; 1419 { 1420 struct pipe *rpipe; 1421 struct pipe *wpipe; 1422 int levents, revents; 1423 #ifdef MAC 1424 int error; 1425 #endif 1426 1427 revents = 0; 1428 rpipe = fp->f_data; 1429 wpipe = PIPE_PEER(rpipe); 1430 PIPE_LOCK(rpipe); 1431 #ifdef MAC 1432 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair); 1433 if (error) 1434 goto locked_error; 1435 #endif 1436 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) 1437 if ((rpipe->pipe_state & PIPE_DIRECTW) || 1438 (rpipe->pipe_buffer.cnt > 0)) 1439 revents |= events & (POLLIN | POLLRDNORM); 1440 1441 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) 1442 if (wpipe->pipe_present != PIPE_ACTIVE || 1443 (wpipe->pipe_state & PIPE_EOF) || 1444 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) && 1445 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF || 1446 wpipe->pipe_buffer.size == 0))) 1447 revents |= events & (POLLOUT | POLLWRNORM); 1448 1449 levents = events & 1450 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND); 1451 if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents && 1452 fp->f_seqcount == rpipe->pipe_wgen) 1453 events |= POLLINIGNEOF; 1454 1455 if ((events & POLLINIGNEOF) == 0) { 1456 if (rpipe->pipe_state & PIPE_EOF) { 1457 revents |= (events & (POLLIN | POLLRDNORM)); 1458 if (wpipe->pipe_present != PIPE_ACTIVE || 1459 (wpipe->pipe_state & PIPE_EOF)) 1460 revents |= POLLHUP; 1461 } 1462 } 1463 1464 if (revents == 0) { 1465 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) { 1466 selrecord(td, &rpipe->pipe_sel); 1467 if (SEL_WAITING(&rpipe->pipe_sel)) 1468 rpipe->pipe_state |= PIPE_SEL; 1469 } 1470 1471 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) { 1472 selrecord(td, &wpipe->pipe_sel); 1473 if (SEL_WAITING(&wpipe->pipe_sel)) 1474 wpipe->pipe_state |= PIPE_SEL; 1475 } 1476 } 1477 #ifdef MAC 1478 locked_error: 1479 #endif 1480 PIPE_UNLOCK(rpipe); 1481 1482 return (revents); 1483 } 1484 1485 /* 1486 * We shouldn't need locks here as we're doing a read and this should 1487 * be a natural race. 1488 */ 1489 static int 1490 pipe_stat(fp, ub, active_cred, td) 1491 struct file *fp; 1492 struct stat *ub; 1493 struct ucred *active_cred; 1494 struct thread *td; 1495 { 1496 struct pipe *pipe; 1497 int new_unr; 1498 #ifdef MAC 1499 int error; 1500 #endif 1501 1502 pipe = fp->f_data; 1503 PIPE_LOCK(pipe); 1504 #ifdef MAC 1505 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair); 1506 if (error) { 1507 PIPE_UNLOCK(pipe); 1508 return (error); 1509 } 1510 #endif 1511 1512 /* For named pipes ask the underlying filesystem. */ 1513 if (pipe->pipe_state & PIPE_NAMED) { 1514 PIPE_UNLOCK(pipe); 1515 return (vnops.fo_stat(fp, ub, active_cred, td)); 1516 } 1517 1518 /* 1519 * Lazily allocate an inode number for the pipe. Most pipe 1520 * users do not call fstat(2) on the pipe, which means that 1521 * postponing the inode allocation until it is must be 1522 * returned to userland is useful. If alloc_unr failed, 1523 * assign st_ino zero instead of returning an error. 1524 * Special pipe_ino values: 1525 * -1 - not yet initialized; 1526 * 0 - alloc_unr failed, return 0 as st_ino forever. 1527 */ 1528 if (pipe->pipe_ino == (ino_t)-1) { 1529 new_unr = alloc_unr(pipeino_unr); 1530 if (new_unr != -1) 1531 pipe->pipe_ino = new_unr; 1532 else 1533 pipe->pipe_ino = 0; 1534 } 1535 PIPE_UNLOCK(pipe); 1536 1537 bzero(ub, sizeof(*ub)); 1538 ub->st_mode = S_IFIFO; 1539 ub->st_blksize = PAGE_SIZE; 1540 if (pipe->pipe_state & PIPE_DIRECTW) 1541 ub->st_size = pipe->pipe_map.cnt; 1542 else 1543 ub->st_size = pipe->pipe_buffer.cnt; 1544 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize; 1545 ub->st_atim = pipe->pipe_atime; 1546 ub->st_mtim = pipe->pipe_mtime; 1547 ub->st_ctim = pipe->pipe_ctime; 1548 ub->st_uid = fp->f_cred->cr_uid; 1549 ub->st_gid = fp->f_cred->cr_gid; 1550 ub->st_dev = pipedev_ino; 1551 ub->st_ino = pipe->pipe_ino; 1552 /* 1553 * Left as 0: st_nlink, st_rdev, st_flags, st_gen. 1554 */ 1555 return (0); 1556 } 1557 1558 /* ARGSUSED */ 1559 static int 1560 pipe_close(fp, td) 1561 struct file *fp; 1562 struct thread *td; 1563 { 1564 1565 if (fp->f_vnode != NULL) 1566 return vnops.fo_close(fp, td); 1567 fp->f_ops = &badfileops; 1568 pipe_dtor(fp->f_data); 1569 fp->f_data = NULL; 1570 return (0); 1571 } 1572 1573 static int 1574 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td) 1575 { 1576 struct pipe *cpipe; 1577 int error; 1578 1579 cpipe = fp->f_data; 1580 if (cpipe->pipe_state & PIPE_NAMED) 1581 error = vn_chmod(fp, mode, active_cred, td); 1582 else 1583 error = invfo_chmod(fp, mode, active_cred, td); 1584 return (error); 1585 } 1586 1587 static int 1588 pipe_chown(fp, uid, gid, active_cred, td) 1589 struct file *fp; 1590 uid_t uid; 1591 gid_t gid; 1592 struct ucred *active_cred; 1593 struct thread *td; 1594 { 1595 struct pipe *cpipe; 1596 int error; 1597 1598 cpipe = fp->f_data; 1599 if (cpipe->pipe_state & PIPE_NAMED) 1600 error = vn_chown(fp, uid, gid, active_cred, td); 1601 else 1602 error = invfo_chown(fp, uid, gid, active_cred, td); 1603 return (error); 1604 } 1605 1606 static void 1607 pipe_free_kmem(cpipe) 1608 struct pipe *cpipe; 1609 { 1610 1611 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), 1612 ("pipe_free_kmem: pipe mutex locked")); 1613 1614 if (cpipe->pipe_buffer.buffer != NULL) { 1615 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size); 1616 vm_map_remove(pipe_map, 1617 (vm_offset_t)cpipe->pipe_buffer.buffer, 1618 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size); 1619 cpipe->pipe_buffer.buffer = NULL; 1620 } 1621 #ifndef PIPE_NODIRECT 1622 { 1623 cpipe->pipe_map.cnt = 0; 1624 cpipe->pipe_map.pos = 0; 1625 cpipe->pipe_map.npages = 0; 1626 } 1627 #endif 1628 } 1629 1630 /* 1631 * shutdown the pipe 1632 */ 1633 static void 1634 pipeclose(cpipe) 1635 struct pipe *cpipe; 1636 { 1637 struct pipepair *pp; 1638 struct pipe *ppipe; 1639 1640 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL")); 1641 1642 PIPE_LOCK(cpipe); 1643 pipelock(cpipe, 0); 1644 pp = cpipe->pipe_pair; 1645 1646 pipeselwakeup(cpipe); 1647 1648 /* 1649 * If the other side is blocked, wake it up saying that 1650 * we want to close it down. 1651 */ 1652 cpipe->pipe_state |= PIPE_EOF; 1653 while (cpipe->pipe_busy) { 1654 wakeup(cpipe); 1655 cpipe->pipe_state |= PIPE_WANT; 1656 pipeunlock(cpipe); 1657 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0); 1658 pipelock(cpipe, 0); 1659 } 1660 1661 1662 /* 1663 * Disconnect from peer, if any. 1664 */ 1665 ppipe = cpipe->pipe_peer; 1666 if (ppipe->pipe_present == PIPE_ACTIVE) { 1667 pipeselwakeup(ppipe); 1668 1669 ppipe->pipe_state |= PIPE_EOF; 1670 wakeup(ppipe); 1671 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0); 1672 } 1673 1674 /* 1675 * Mark this endpoint as free. Release kmem resources. We 1676 * don't mark this endpoint as unused until we've finished 1677 * doing that, or the pipe might disappear out from under 1678 * us. 1679 */ 1680 PIPE_UNLOCK(cpipe); 1681 pipe_free_kmem(cpipe); 1682 PIPE_LOCK(cpipe); 1683 cpipe->pipe_present = PIPE_CLOSING; 1684 pipeunlock(cpipe); 1685 1686 /* 1687 * knlist_clear() may sleep dropping the PIPE_MTX. Set the 1688 * PIPE_FINALIZED, that allows other end to free the 1689 * pipe_pair, only after the knotes are completely dismantled. 1690 */ 1691 knlist_clear(&cpipe->pipe_sel.si_note, 1); 1692 cpipe->pipe_present = PIPE_FINALIZED; 1693 seldrain(&cpipe->pipe_sel); 1694 knlist_destroy(&cpipe->pipe_sel.si_note); 1695 1696 /* 1697 * If both endpoints are now closed, release the memory for the 1698 * pipe pair. If not, unlock. 1699 */ 1700 if (ppipe->pipe_present == PIPE_FINALIZED) { 1701 PIPE_UNLOCK(cpipe); 1702 #ifdef MAC 1703 mac_pipe_destroy(pp); 1704 #endif 1705 uma_zfree(pipe_zone, cpipe->pipe_pair); 1706 } else 1707 PIPE_UNLOCK(cpipe); 1708 } 1709 1710 /*ARGSUSED*/ 1711 static int 1712 pipe_kqfilter(struct file *fp, struct knote *kn) 1713 { 1714 struct pipe *cpipe; 1715 1716 /* 1717 * If a filter is requested that is not supported by this file 1718 * descriptor, don't return an error, but also don't ever generate an 1719 * event. 1720 */ 1721 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) { 1722 kn->kn_fop = &pipe_nfiltops; 1723 return (0); 1724 } 1725 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) { 1726 kn->kn_fop = &pipe_nfiltops; 1727 return (0); 1728 } 1729 cpipe = fp->f_data; 1730 PIPE_LOCK(cpipe); 1731 switch (kn->kn_filter) { 1732 case EVFILT_READ: 1733 kn->kn_fop = &pipe_rfiltops; 1734 break; 1735 case EVFILT_WRITE: 1736 kn->kn_fop = &pipe_wfiltops; 1737 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) { 1738 /* other end of pipe has been closed */ 1739 PIPE_UNLOCK(cpipe); 1740 return (EPIPE); 1741 } 1742 cpipe = PIPE_PEER(cpipe); 1743 break; 1744 default: 1745 PIPE_UNLOCK(cpipe); 1746 return (EINVAL); 1747 } 1748 1749 kn->kn_hook = cpipe; 1750 knlist_add(&cpipe->pipe_sel.si_note, kn, 1); 1751 PIPE_UNLOCK(cpipe); 1752 return (0); 1753 } 1754 1755 static void 1756 filt_pipedetach(struct knote *kn) 1757 { 1758 struct pipe *cpipe = kn->kn_hook; 1759 1760 PIPE_LOCK(cpipe); 1761 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1); 1762 PIPE_UNLOCK(cpipe); 1763 } 1764 1765 /*ARGSUSED*/ 1766 static int 1767 filt_piperead(struct knote *kn, long hint) 1768 { 1769 struct pipe *rpipe = kn->kn_hook; 1770 struct pipe *wpipe = rpipe->pipe_peer; 1771 int ret; 1772 1773 PIPE_LOCK(rpipe); 1774 kn->kn_data = rpipe->pipe_buffer.cnt; 1775 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) 1776 kn->kn_data = rpipe->pipe_map.cnt; 1777 1778 if ((rpipe->pipe_state & PIPE_EOF) || 1779 wpipe->pipe_present != PIPE_ACTIVE || 1780 (wpipe->pipe_state & PIPE_EOF)) { 1781 kn->kn_flags |= EV_EOF; 1782 PIPE_UNLOCK(rpipe); 1783 return (1); 1784 } 1785 ret = kn->kn_data > 0; 1786 PIPE_UNLOCK(rpipe); 1787 return ret; 1788 } 1789 1790 /*ARGSUSED*/ 1791 static int 1792 filt_pipewrite(struct knote *kn, long hint) 1793 { 1794 struct pipe *wpipe; 1795 1796 wpipe = kn->kn_hook; 1797 PIPE_LOCK(wpipe); 1798 if (wpipe->pipe_present != PIPE_ACTIVE || 1799 (wpipe->pipe_state & PIPE_EOF)) { 1800 kn->kn_data = 0; 1801 kn->kn_flags |= EV_EOF; 1802 PIPE_UNLOCK(wpipe); 1803 return (1); 1804 } 1805 kn->kn_data = (wpipe->pipe_buffer.size > 0) ? 1806 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF; 1807 if (wpipe->pipe_state & PIPE_DIRECTW) 1808 kn->kn_data = 0; 1809 1810 PIPE_UNLOCK(wpipe); 1811 return (kn->kn_data >= PIPE_BUF); 1812 } 1813 1814 static void 1815 filt_pipedetach_notsup(struct knote *kn) 1816 { 1817 1818 } 1819 1820 static int 1821 filt_pipenotsup(struct knote *kn, long hint) 1822 { 1823 1824 return (0); 1825 }
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