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 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice immediately at the beginning of the file, without modification, 10 * this list of conditions, and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Absolutely no warranty of function or purpose is made by the author 15 * John S. Dyson. 16 * 4. Modifications may be freely made to this file if the above conditions 17 * are met. 18 */ 19 20 /* 21 * This file contains a high-performance replacement for the socket-based 22 * pipes scheme originally used in FreeBSD/4.4Lite. It does not support 23 * all features of sockets, but does do everything that pipes normally 24 * do. 25 */ 26 27 /* 28 * This code has two modes of operation, a small write mode and a large 29 * write mode. The small write mode acts like conventional pipes with 30 * a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the 31 * "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT 32 * and PIPE_SIZE in size, the sending process pins the underlying pages in 33 * memory, and the receiving process copies directly from these pinned pages 34 * in the sending process. 35 * 36 * If the sending process receives a signal, it is possible that it will 37 * go away, and certainly its address space can change, because control 38 * is returned back to the user-mode side. In that case, the pipe code 39 * arranges to copy the buffer supplied by the user process, to a pageable 40 * kernel buffer, and the receiving process will grab the data from the 41 * pageable kernel buffer. Since signals don't happen all that often, 42 * the copy operation is normally eliminated. 43 * 44 * The constant PIPE_MINDIRECT is chosen to make sure that buffering will 45 * happen for small transfers so that the system will not spend all of 46 * its time context switching. 47 * 48 * In order to limit the resource use of pipes, two sysctls exist: 49 * 50 * kern.ipc.maxpipekva - This is a hard limit on the amount of pageable 51 * address space available to us in pipe_map. This value is normally 52 * autotuned, but may also be loader tuned. 53 * 54 * kern.ipc.pipekva - This read-only sysctl tracks the current amount of 55 * memory in use by pipes. 56 * 57 * Based on how large pipekva is relative to maxpipekva, the following 58 * will happen: 59 * 60 * 0% - 50%: 61 * New pipes are given 16K of memory backing, pipes may dynamically 62 * grow to as large as 64K where needed. 63 * 50% - 75%: 64 * New pipes are given 4K (or PAGE_SIZE) of memory backing, 65 * existing pipes may NOT grow. 66 * 75% - 100%: 67 * New pipes are given 4K (or PAGE_SIZE) of memory backing, 68 * existing pipes will be shrunk down to 4K whenever possible. 69 * 70 * Resizing may be disabled by setting kern.ipc.piperesizeallowed=0. If 71 * that is set, the only resize that will occur is the 0 -> SMALL_PIPE_SIZE 72 * resize which MUST occur for reverse-direction pipes when they are 73 * first used. 74 * 75 * Additional information about the current state of pipes may be obtained 76 * from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail, 77 * and kern.ipc.piperesizefail. 78 * 79 * Locking rules: There are two locks present here: A mutex, used via 80 * PIPE_LOCK, and a flag, used via pipelock(). All locking is done via 81 * the flag, as mutexes can not persist over uiomove. The mutex 82 * exists only to guard access to the flag, and is not in itself a 83 * locking mechanism. Also note that there is only a single mutex for 84 * both directions of a pipe. 85 * 86 * As pipelock() may have to sleep before it can acquire the flag, it 87 * is important to reread all data after a call to pipelock(); everything 88 * in the structure may have changed. 89 */ 90 91 #include <sys/cdefs.h> 92 __FBSDID("$FreeBSD: releng/9.1/sys/kern/sys_pipe.c 233353 2012-03-23 11:26:54Z kib $"); 93 94 #include <sys/param.h> 95 #include <sys/systm.h> 96 #include <sys/conf.h> 97 #include <sys/fcntl.h> 98 #include <sys/file.h> 99 #include <sys/filedesc.h> 100 #include <sys/filio.h> 101 #include <sys/kernel.h> 102 #include <sys/lock.h> 103 #include <sys/mutex.h> 104 #include <sys/ttycom.h> 105 #include <sys/stat.h> 106 #include <sys/malloc.h> 107 #include <sys/poll.h> 108 #include <sys/selinfo.h> 109 #include <sys/signalvar.h> 110 #include <sys/syscallsubr.h> 111 #include <sys/sysctl.h> 112 #include <sys/sysproto.h> 113 #include <sys/pipe.h> 114 #include <sys/proc.h> 115 #include <sys/vnode.h> 116 #include <sys/uio.h> 117 #include <sys/event.h> 118 119 #include <security/mac/mac_framework.h> 120 121 #include <vm/vm.h> 122 #include <vm/vm_param.h> 123 #include <vm/vm_object.h> 124 #include <vm/vm_kern.h> 125 #include <vm/vm_extern.h> 126 #include <vm/pmap.h> 127 #include <vm/vm_map.h> 128 #include <vm/vm_page.h> 129 #include <vm/uma.h> 130 131 /* 132 * Use this define if you want to disable *fancy* VM things. Expect an 133 * approx 30% decrease in transfer rate. This could be useful for 134 * NetBSD or OpenBSD. 135 */ 136 /* #define PIPE_NODIRECT */ 137 138 /* 139 * interfaces to the outside world 140 */ 141 static fo_rdwr_t pipe_read; 142 static fo_rdwr_t pipe_write; 143 static fo_truncate_t pipe_truncate; 144 static fo_ioctl_t pipe_ioctl; 145 static fo_poll_t pipe_poll; 146 static fo_kqfilter_t pipe_kqfilter; 147 static fo_stat_t pipe_stat; 148 static fo_close_t pipe_close; 149 150 static struct fileops pipeops = { 151 .fo_read = pipe_read, 152 .fo_write = pipe_write, 153 .fo_truncate = pipe_truncate, 154 .fo_ioctl = pipe_ioctl, 155 .fo_poll = pipe_poll, 156 .fo_kqfilter = pipe_kqfilter, 157 .fo_stat = pipe_stat, 158 .fo_close = pipe_close, 159 .fo_chmod = invfo_chmod, 160 .fo_chown = invfo_chown, 161 .fo_flags = DFLAG_PASSABLE 162 }; 163 164 static void filt_pipedetach(struct knote *kn); 165 static int filt_piperead(struct knote *kn, long hint); 166 static int filt_pipewrite(struct knote *kn, long hint); 167 168 static struct filterops pipe_rfiltops = { 169 .f_isfd = 1, 170 .f_detach = filt_pipedetach, 171 .f_event = filt_piperead 172 }; 173 static struct filterops pipe_wfiltops = { 174 .f_isfd = 1, 175 .f_detach = filt_pipedetach, 176 .f_event = filt_pipewrite 177 }; 178 179 /* 180 * Default pipe buffer size(s), this can be kind-of large now because pipe 181 * space is pageable. The pipe code will try to maintain locality of 182 * reference for performance reasons, so small amounts of outstanding I/O 183 * will not wipe the cache. 184 */ 185 #define MINPIPESIZE (PIPE_SIZE/3) 186 #define MAXPIPESIZE (2*PIPE_SIZE/3) 187 188 static long amountpipekva; 189 static int pipefragretry; 190 static int pipeallocfail; 191 static int piperesizefail; 192 static int piperesizeallowed = 1; 193 194 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN, 195 &maxpipekva, 0, "Pipe KVA limit"); 196 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD, 197 &amountpipekva, 0, "Pipe KVA usage"); 198 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD, 199 &pipefragretry, 0, "Pipe allocation retries due to fragmentation"); 200 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD, 201 &pipeallocfail, 0, "Pipe allocation failures"); 202 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD, 203 &piperesizefail, 0, "Pipe resize failures"); 204 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW, 205 &piperesizeallowed, 0, "Pipe resizing allowed"); 206 207 static void pipeinit(void *dummy __unused); 208 static void pipeclose(struct pipe *cpipe); 209 static void pipe_free_kmem(struct pipe *cpipe); 210 static int pipe_create(struct pipe *pipe, int backing); 211 static __inline int pipelock(struct pipe *cpipe, int catch); 212 static __inline void pipeunlock(struct pipe *cpipe); 213 static __inline void pipeselwakeup(struct pipe *cpipe); 214 #ifndef PIPE_NODIRECT 215 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio); 216 static void pipe_destroy_write_buffer(struct pipe *wpipe); 217 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio); 218 static void pipe_clone_write_buffer(struct pipe *wpipe); 219 #endif 220 static int pipespace(struct pipe *cpipe, int size); 221 static int pipespace_new(struct pipe *cpipe, int size); 222 223 static int pipe_zone_ctor(void *mem, int size, void *arg, int flags); 224 static int pipe_zone_init(void *mem, int size, int flags); 225 static void pipe_zone_fini(void *mem, int size); 226 227 static uma_zone_t pipe_zone; 228 static struct unrhdr *pipeino_unr; 229 static dev_t pipedev_ino; 230 231 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL); 232 233 static void 234 pipeinit(void *dummy __unused) 235 { 236 237 pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair), 238 pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini, 239 UMA_ALIGN_PTR, 0); 240 KASSERT(pipe_zone != NULL, ("pipe_zone not initialized")); 241 pipeino_unr = new_unrhdr(1, INT32_MAX, NULL); 242 KASSERT(pipeino_unr != NULL, ("pipe fake inodes not initialized")); 243 pipedev_ino = devfs_alloc_cdp_inode(); 244 KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized")); 245 } 246 247 static int 248 pipe_zone_ctor(void *mem, int size, void *arg, int flags) 249 { 250 struct pipepair *pp; 251 struct pipe *rpipe, *wpipe; 252 253 KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size")); 254 255 pp = (struct pipepair *)mem; 256 257 /* 258 * We zero both pipe endpoints to make sure all the kmem pointers 259 * are NULL, flag fields are zero'd, etc. We timestamp both 260 * endpoints with the same time. 261 */ 262 rpipe = &pp->pp_rpipe; 263 bzero(rpipe, sizeof(*rpipe)); 264 vfs_timestamp(&rpipe->pipe_ctime); 265 rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime; 266 267 wpipe = &pp->pp_wpipe; 268 bzero(wpipe, sizeof(*wpipe)); 269 wpipe->pipe_ctime = rpipe->pipe_ctime; 270 wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime; 271 272 rpipe->pipe_peer = wpipe; 273 rpipe->pipe_pair = pp; 274 wpipe->pipe_peer = rpipe; 275 wpipe->pipe_pair = pp; 276 277 /* 278 * Mark both endpoints as present; they will later get free'd 279 * one at a time. When both are free'd, then the whole pair 280 * is released. 281 */ 282 rpipe->pipe_present = PIPE_ACTIVE; 283 wpipe->pipe_present = PIPE_ACTIVE; 284 285 /* 286 * Eventually, the MAC Framework may initialize the label 287 * in ctor or init, but for now we do it elswhere to avoid 288 * blocking in ctor or init. 289 */ 290 pp->pp_label = NULL; 291 292 return (0); 293 } 294 295 static int 296 pipe_zone_init(void *mem, int size, int flags) 297 { 298 struct pipepair *pp; 299 300 KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size")); 301 302 pp = (struct pipepair *)mem; 303 304 mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_RECURSE); 305 return (0); 306 } 307 308 static void 309 pipe_zone_fini(void *mem, int size) 310 { 311 struct pipepair *pp; 312 313 KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size")); 314 315 pp = (struct pipepair *)mem; 316 317 mtx_destroy(&pp->pp_mtx); 318 } 319 320 /* 321 * The pipe system call for the DTYPE_PIPE type of pipes. If we fail, let 322 * the zone pick up the pieces via pipeclose(). 323 */ 324 int 325 kern_pipe(struct thread *td, int fildes[2]) 326 { 327 struct filedesc *fdp = td->td_proc->p_fd; 328 struct file *rf, *wf; 329 struct pipepair *pp; 330 struct pipe *rpipe, *wpipe; 331 int fd, error; 332 333 pp = uma_zalloc(pipe_zone, M_WAITOK); 334 #ifdef MAC 335 /* 336 * The MAC label is shared between the connected endpoints. As a 337 * result mac_pipe_init() and mac_pipe_create() are called once 338 * for the pair, and not on the endpoints. 339 */ 340 mac_pipe_init(pp); 341 mac_pipe_create(td->td_ucred, pp); 342 #endif 343 rpipe = &pp->pp_rpipe; 344 wpipe = &pp->pp_wpipe; 345 346 knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe)); 347 knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe)); 348 349 /* Only the forward direction pipe is backed by default */ 350 if ((error = pipe_create(rpipe, 1)) != 0 || 351 (error = pipe_create(wpipe, 0)) != 0) { 352 pipeclose(rpipe); 353 pipeclose(wpipe); 354 return (error); 355 } 356 357 rpipe->pipe_state |= PIPE_DIRECTOK; 358 wpipe->pipe_state |= PIPE_DIRECTOK; 359 360 error = falloc(td, &rf, &fd, 0); 361 if (error) { 362 pipeclose(rpipe); 363 pipeclose(wpipe); 364 return (error); 365 } 366 /* An extra reference on `rf' has been held for us by falloc(). */ 367 fildes[0] = fd; 368 369 /* 370 * Warning: once we've gotten past allocation of the fd for the 371 * read-side, we can only drop the read side via fdrop() in order 372 * to avoid races against processes which manage to dup() the read 373 * side while we are blocked trying to allocate the write side. 374 */ 375 finit(rf, FREAD | FWRITE, DTYPE_PIPE, rpipe, &pipeops); 376 error = falloc(td, &wf, &fd, 0); 377 if (error) { 378 fdclose(fdp, rf, fildes[0], td); 379 fdrop(rf, td); 380 /* rpipe has been closed by fdrop(). */ 381 pipeclose(wpipe); 382 return (error); 383 } 384 /* An extra reference on `wf' has been held for us by falloc(). */ 385 finit(wf, FREAD | FWRITE, DTYPE_PIPE, wpipe, &pipeops); 386 fdrop(wf, td); 387 fildes[1] = fd; 388 fdrop(rf, td); 389 390 return (0); 391 } 392 393 /* ARGSUSED */ 394 int 395 sys_pipe(struct thread *td, struct pipe_args *uap) 396 { 397 int error; 398 int fildes[2]; 399 400 error = kern_pipe(td, fildes); 401 if (error) 402 return (error); 403 404 td->td_retval[0] = fildes[0]; 405 td->td_retval[1] = fildes[1]; 406 407 return (0); 408 } 409 410 /* 411 * Allocate kva for pipe circular buffer, the space is pageable 412 * This routine will 'realloc' the size of a pipe safely, if it fails 413 * it will retain the old buffer. 414 * If it fails it will return ENOMEM. 415 */ 416 static int 417 pipespace_new(cpipe, size) 418 struct pipe *cpipe; 419 int size; 420 { 421 caddr_t buffer; 422 int error, cnt, firstseg; 423 static int curfail = 0; 424 static struct timeval lastfail; 425 426 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked")); 427 KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW), 428 ("pipespace: resize of direct writes not allowed")); 429 retry: 430 cnt = cpipe->pipe_buffer.cnt; 431 if (cnt > size) 432 size = cnt; 433 434 size = round_page(size); 435 buffer = (caddr_t) vm_map_min(pipe_map); 436 437 error = vm_map_find(pipe_map, NULL, 0, 438 (vm_offset_t *) &buffer, size, 1, 439 VM_PROT_ALL, VM_PROT_ALL, 0); 440 if (error != KERN_SUCCESS) { 441 if ((cpipe->pipe_buffer.buffer == NULL) && 442 (size > SMALL_PIPE_SIZE)) { 443 size = SMALL_PIPE_SIZE; 444 pipefragretry++; 445 goto retry; 446 } 447 if (cpipe->pipe_buffer.buffer == NULL) { 448 pipeallocfail++; 449 if (ppsratecheck(&lastfail, &curfail, 1)) 450 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n"); 451 } else { 452 piperesizefail++; 453 } 454 return (ENOMEM); 455 } 456 457 /* copy data, then free old resources if we're resizing */ 458 if (cnt > 0) { 459 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) { 460 firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out; 461 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 462 buffer, firstseg); 463 if ((cnt - firstseg) > 0) 464 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg], 465 cpipe->pipe_buffer.in); 466 } else { 467 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 468 buffer, cnt); 469 } 470 } 471 pipe_free_kmem(cpipe); 472 cpipe->pipe_buffer.buffer = buffer; 473 cpipe->pipe_buffer.size = size; 474 cpipe->pipe_buffer.in = cnt; 475 cpipe->pipe_buffer.out = 0; 476 cpipe->pipe_buffer.cnt = cnt; 477 atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size); 478 return (0); 479 } 480 481 /* 482 * Wrapper for pipespace_new() that performs locking assertions. 483 */ 484 static int 485 pipespace(cpipe, size) 486 struct pipe *cpipe; 487 int size; 488 { 489 490 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 491 ("Unlocked pipe passed to pipespace")); 492 return (pipespace_new(cpipe, size)); 493 } 494 495 /* 496 * lock a pipe for I/O, blocking other access 497 */ 498 static __inline int 499 pipelock(cpipe, catch) 500 struct pipe *cpipe; 501 int catch; 502 { 503 int error; 504 505 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 506 while (cpipe->pipe_state & PIPE_LOCKFL) { 507 cpipe->pipe_state |= PIPE_LWANT; 508 error = msleep(cpipe, PIPE_MTX(cpipe), 509 catch ? (PRIBIO | PCATCH) : PRIBIO, 510 "pipelk", 0); 511 if (error != 0) 512 return (error); 513 } 514 cpipe->pipe_state |= PIPE_LOCKFL; 515 return (0); 516 } 517 518 /* 519 * unlock a pipe I/O lock 520 */ 521 static __inline void 522 pipeunlock(cpipe) 523 struct pipe *cpipe; 524 { 525 526 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 527 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 528 ("Unlocked pipe passed to pipeunlock")); 529 cpipe->pipe_state &= ~PIPE_LOCKFL; 530 if (cpipe->pipe_state & PIPE_LWANT) { 531 cpipe->pipe_state &= ~PIPE_LWANT; 532 wakeup(cpipe); 533 } 534 } 535 536 static __inline void 537 pipeselwakeup(cpipe) 538 struct pipe *cpipe; 539 { 540 541 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 542 if (cpipe->pipe_state & PIPE_SEL) { 543 selwakeuppri(&cpipe->pipe_sel, PSOCK); 544 if (!SEL_WAITING(&cpipe->pipe_sel)) 545 cpipe->pipe_state &= ~PIPE_SEL; 546 } 547 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) 548 pgsigio(&cpipe->pipe_sigio, SIGIO, 0); 549 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0); 550 } 551 552 /* 553 * Initialize and allocate VM and memory for pipe. The structure 554 * will start out zero'd from the ctor, so we just manage the kmem. 555 */ 556 static int 557 pipe_create(pipe, backing) 558 struct pipe *pipe; 559 int backing; 560 { 561 int error; 562 563 if (backing) { 564 if (amountpipekva > maxpipekva / 2) 565 error = pipespace_new(pipe, SMALL_PIPE_SIZE); 566 else 567 error = pipespace_new(pipe, PIPE_SIZE); 568 } else { 569 /* If we're not backing this pipe, no need to do anything. */ 570 error = 0; 571 } 572 pipe->pipe_ino = -1; 573 return (error); 574 } 575 576 /* ARGSUSED */ 577 static int 578 pipe_read(fp, uio, active_cred, flags, td) 579 struct file *fp; 580 struct uio *uio; 581 struct ucred *active_cred; 582 struct thread *td; 583 int flags; 584 { 585 struct pipe *rpipe = fp->f_data; 586 int error; 587 int nread = 0; 588 int size; 589 590 PIPE_LOCK(rpipe); 591 ++rpipe->pipe_busy; 592 error = pipelock(rpipe, 1); 593 if (error) 594 goto unlocked_error; 595 596 #ifdef MAC 597 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair); 598 if (error) 599 goto locked_error; 600 #endif 601 if (amountpipekva > (3 * maxpipekva) / 4) { 602 if (!(rpipe->pipe_state & PIPE_DIRECTW) && 603 (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) && 604 (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) && 605 (piperesizeallowed == 1)) { 606 PIPE_UNLOCK(rpipe); 607 pipespace(rpipe, SMALL_PIPE_SIZE); 608 PIPE_LOCK(rpipe); 609 } 610 } 611 612 while (uio->uio_resid) { 613 /* 614 * normal pipe buffer receive 615 */ 616 if (rpipe->pipe_buffer.cnt > 0) { 617 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 618 if (size > rpipe->pipe_buffer.cnt) 619 size = rpipe->pipe_buffer.cnt; 620 if (size > uio->uio_resid) 621 size = uio->uio_resid; 622 623 PIPE_UNLOCK(rpipe); 624 error = uiomove( 625 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 626 size, uio); 627 PIPE_LOCK(rpipe); 628 if (error) 629 break; 630 631 rpipe->pipe_buffer.out += size; 632 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 633 rpipe->pipe_buffer.out = 0; 634 635 rpipe->pipe_buffer.cnt -= size; 636 637 /* 638 * If there is no more to read in the pipe, reset 639 * its pointers to the beginning. This improves 640 * cache hit stats. 641 */ 642 if (rpipe->pipe_buffer.cnt == 0) { 643 rpipe->pipe_buffer.in = 0; 644 rpipe->pipe_buffer.out = 0; 645 } 646 nread += size; 647 #ifndef PIPE_NODIRECT 648 /* 649 * Direct copy, bypassing a kernel buffer. 650 */ 651 } else if ((size = rpipe->pipe_map.cnt) && 652 (rpipe->pipe_state & PIPE_DIRECTW)) { 653 if (size > uio->uio_resid) 654 size = (u_int) uio->uio_resid; 655 656 PIPE_UNLOCK(rpipe); 657 error = uiomove_fromphys(rpipe->pipe_map.ms, 658 rpipe->pipe_map.pos, size, uio); 659 PIPE_LOCK(rpipe); 660 if (error) 661 break; 662 nread += size; 663 rpipe->pipe_map.pos += size; 664 rpipe->pipe_map.cnt -= size; 665 if (rpipe->pipe_map.cnt == 0) { 666 rpipe->pipe_state &= ~PIPE_DIRECTW; 667 wakeup(rpipe); 668 } 669 #endif 670 } else { 671 /* 672 * detect EOF condition 673 * read returns 0 on EOF, no need to set error 674 */ 675 if (rpipe->pipe_state & PIPE_EOF) 676 break; 677 678 /* 679 * If the "write-side" has been blocked, wake it up now. 680 */ 681 if (rpipe->pipe_state & PIPE_WANTW) { 682 rpipe->pipe_state &= ~PIPE_WANTW; 683 wakeup(rpipe); 684 } 685 686 /* 687 * Break if some data was read. 688 */ 689 if (nread > 0) 690 break; 691 692 /* 693 * Unlock the pipe buffer for our remaining processing. 694 * We will either break out with an error or we will 695 * sleep and relock to loop. 696 */ 697 pipeunlock(rpipe); 698 699 /* 700 * Handle non-blocking mode operation or 701 * wait for more data. 702 */ 703 if (fp->f_flag & FNONBLOCK) { 704 error = EAGAIN; 705 } else { 706 rpipe->pipe_state |= PIPE_WANTR; 707 if ((error = msleep(rpipe, PIPE_MTX(rpipe), 708 PRIBIO | PCATCH, 709 "piperd", 0)) == 0) 710 error = pipelock(rpipe, 1); 711 } 712 if (error) 713 goto unlocked_error; 714 } 715 } 716 #ifdef MAC 717 locked_error: 718 #endif 719 pipeunlock(rpipe); 720 721 /* XXX: should probably do this before getting any locks. */ 722 if (error == 0) 723 vfs_timestamp(&rpipe->pipe_atime); 724 unlocked_error: 725 --rpipe->pipe_busy; 726 727 /* 728 * PIPE_WANT processing only makes sense if pipe_busy is 0. 729 */ 730 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 731 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 732 wakeup(rpipe); 733 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 734 /* 735 * Handle write blocking hysteresis. 736 */ 737 if (rpipe->pipe_state & PIPE_WANTW) { 738 rpipe->pipe_state &= ~PIPE_WANTW; 739 wakeup(rpipe); 740 } 741 } 742 743 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF) 744 pipeselwakeup(rpipe); 745 746 PIPE_UNLOCK(rpipe); 747 return (error); 748 } 749 750 #ifndef PIPE_NODIRECT 751 /* 752 * Map the sending processes' buffer into kernel space and wire it. 753 * This is similar to a physical write operation. 754 */ 755 static int 756 pipe_build_write_buffer(wpipe, uio) 757 struct pipe *wpipe; 758 struct uio *uio; 759 { 760 u_int size; 761 int i; 762 763 PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED); 764 KASSERT(wpipe->pipe_state & PIPE_DIRECTW, 765 ("Clone attempt on non-direct write pipe!")); 766 767 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size) 768 size = wpipe->pipe_buffer.size; 769 else 770 size = uio->uio_iov->iov_len; 771 772 if ((i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 773 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ, 774 wpipe->pipe_map.ms, PIPENPAGES)) < 0) 775 return (EFAULT); 776 777 /* 778 * set up the control block 779 */ 780 wpipe->pipe_map.npages = i; 781 wpipe->pipe_map.pos = 782 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 783 wpipe->pipe_map.cnt = size; 784 785 /* 786 * and update the uio data 787 */ 788 789 uio->uio_iov->iov_len -= size; 790 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size; 791 if (uio->uio_iov->iov_len == 0) 792 uio->uio_iov++; 793 uio->uio_resid -= size; 794 uio->uio_offset += size; 795 return (0); 796 } 797 798 /* 799 * unmap and unwire the process buffer 800 */ 801 static void 802 pipe_destroy_write_buffer(wpipe) 803 struct pipe *wpipe; 804 { 805 806 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 807 vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages); 808 wpipe->pipe_map.npages = 0; 809 } 810 811 /* 812 * In the case of a signal, the writing process might go away. This 813 * code copies the data into the circular buffer so that the source 814 * pages can be freed without loss of data. 815 */ 816 static void 817 pipe_clone_write_buffer(wpipe) 818 struct pipe *wpipe; 819 { 820 struct uio uio; 821 struct iovec iov; 822 int size; 823 int pos; 824 825 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 826 size = wpipe->pipe_map.cnt; 827 pos = wpipe->pipe_map.pos; 828 829 wpipe->pipe_buffer.in = size; 830 wpipe->pipe_buffer.out = 0; 831 wpipe->pipe_buffer.cnt = size; 832 wpipe->pipe_state &= ~PIPE_DIRECTW; 833 834 PIPE_UNLOCK(wpipe); 835 iov.iov_base = wpipe->pipe_buffer.buffer; 836 iov.iov_len = size; 837 uio.uio_iov = &iov; 838 uio.uio_iovcnt = 1; 839 uio.uio_offset = 0; 840 uio.uio_resid = size; 841 uio.uio_segflg = UIO_SYSSPACE; 842 uio.uio_rw = UIO_READ; 843 uio.uio_td = curthread; 844 uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio); 845 PIPE_LOCK(wpipe); 846 pipe_destroy_write_buffer(wpipe); 847 } 848 849 /* 850 * This implements the pipe buffer write mechanism. Note that only 851 * a direct write OR a normal pipe write can be pending at any given time. 852 * If there are any characters in the pipe buffer, the direct write will 853 * be deferred until the receiving process grabs all of the bytes from 854 * the pipe buffer. Then the direct mapping write is set-up. 855 */ 856 static int 857 pipe_direct_write(wpipe, uio) 858 struct pipe *wpipe; 859 struct uio *uio; 860 { 861 int error; 862 863 retry: 864 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 865 error = pipelock(wpipe, 1); 866 if (wpipe->pipe_state & PIPE_EOF) 867 error = EPIPE; 868 if (error) { 869 pipeunlock(wpipe); 870 goto error1; 871 } 872 while (wpipe->pipe_state & PIPE_DIRECTW) { 873 if (wpipe->pipe_state & PIPE_WANTR) { 874 wpipe->pipe_state &= ~PIPE_WANTR; 875 wakeup(wpipe); 876 } 877 pipeselwakeup(wpipe); 878 wpipe->pipe_state |= PIPE_WANTW; 879 pipeunlock(wpipe); 880 error = msleep(wpipe, PIPE_MTX(wpipe), 881 PRIBIO | PCATCH, "pipdww", 0); 882 if (error) 883 goto error1; 884 else 885 goto retry; 886 } 887 wpipe->pipe_map.cnt = 0; /* transfer not ready yet */ 888 if (wpipe->pipe_buffer.cnt > 0) { 889 if (wpipe->pipe_state & PIPE_WANTR) { 890 wpipe->pipe_state &= ~PIPE_WANTR; 891 wakeup(wpipe); 892 } 893 pipeselwakeup(wpipe); 894 wpipe->pipe_state |= PIPE_WANTW; 895 pipeunlock(wpipe); 896 error = msleep(wpipe, PIPE_MTX(wpipe), 897 PRIBIO | PCATCH, "pipdwc", 0); 898 if (error) 899 goto error1; 900 else 901 goto retry; 902 } 903 904 wpipe->pipe_state |= PIPE_DIRECTW; 905 906 PIPE_UNLOCK(wpipe); 907 error = pipe_build_write_buffer(wpipe, uio); 908 PIPE_LOCK(wpipe); 909 if (error) { 910 wpipe->pipe_state &= ~PIPE_DIRECTW; 911 pipeunlock(wpipe); 912 goto error1; 913 } 914 915 error = 0; 916 while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) { 917 if (wpipe->pipe_state & PIPE_EOF) { 918 pipe_destroy_write_buffer(wpipe); 919 pipeselwakeup(wpipe); 920 pipeunlock(wpipe); 921 error = EPIPE; 922 goto error1; 923 } 924 if (wpipe->pipe_state & PIPE_WANTR) { 925 wpipe->pipe_state &= ~PIPE_WANTR; 926 wakeup(wpipe); 927 } 928 pipeselwakeup(wpipe); 929 pipeunlock(wpipe); 930 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH, 931 "pipdwt", 0); 932 pipelock(wpipe, 0); 933 } 934 935 if (wpipe->pipe_state & PIPE_EOF) 936 error = EPIPE; 937 if (wpipe->pipe_state & PIPE_DIRECTW) { 938 /* 939 * this bit of trickery substitutes a kernel buffer for 940 * the process that might be going away. 941 */ 942 pipe_clone_write_buffer(wpipe); 943 } else { 944 pipe_destroy_write_buffer(wpipe); 945 } 946 pipeunlock(wpipe); 947 return (error); 948 949 error1: 950 wakeup(wpipe); 951 return (error); 952 } 953 #endif 954 955 static int 956 pipe_write(fp, uio, active_cred, flags, td) 957 struct file *fp; 958 struct uio *uio; 959 struct ucred *active_cred; 960 struct thread *td; 961 int flags; 962 { 963 int error = 0; 964 int desiredsize; 965 ssize_t orig_resid; 966 struct pipe *wpipe, *rpipe; 967 968 rpipe = fp->f_data; 969 wpipe = rpipe->pipe_peer; 970 971 PIPE_LOCK(rpipe); 972 error = pipelock(wpipe, 1); 973 if (error) { 974 PIPE_UNLOCK(rpipe); 975 return (error); 976 } 977 /* 978 * detect loss of pipe read side, issue SIGPIPE if lost. 979 */ 980 if (wpipe->pipe_present != PIPE_ACTIVE || 981 (wpipe->pipe_state & PIPE_EOF)) { 982 pipeunlock(wpipe); 983 PIPE_UNLOCK(rpipe); 984 return (EPIPE); 985 } 986 #ifdef MAC 987 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair); 988 if (error) { 989 pipeunlock(wpipe); 990 PIPE_UNLOCK(rpipe); 991 return (error); 992 } 993 #endif 994 ++wpipe->pipe_busy; 995 996 /* Choose a larger size if it's advantageous */ 997 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size); 998 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) { 999 if (piperesizeallowed != 1) 1000 break; 1001 if (amountpipekva > maxpipekva / 2) 1002 break; 1003 if (desiredsize == BIG_PIPE_SIZE) 1004 break; 1005 desiredsize = desiredsize * 2; 1006 } 1007 1008 /* Choose a smaller size if we're in a OOM situation */ 1009 if ((amountpipekva > (3 * maxpipekva) / 4) && 1010 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) && 1011 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) && 1012 (piperesizeallowed == 1)) 1013 desiredsize = SMALL_PIPE_SIZE; 1014 1015 /* Resize if the above determined that a new size was necessary */ 1016 if ((desiredsize != wpipe->pipe_buffer.size) && 1017 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) { 1018 PIPE_UNLOCK(wpipe); 1019 pipespace(wpipe, desiredsize); 1020 PIPE_LOCK(wpipe); 1021 } 1022 if (wpipe->pipe_buffer.size == 0) { 1023 /* 1024 * This can only happen for reverse direction use of pipes 1025 * in a complete OOM situation. 1026 */ 1027 error = ENOMEM; 1028 --wpipe->pipe_busy; 1029 pipeunlock(wpipe); 1030 PIPE_UNLOCK(wpipe); 1031 return (error); 1032 } 1033 1034 pipeunlock(wpipe); 1035 1036 orig_resid = uio->uio_resid; 1037 1038 while (uio->uio_resid) { 1039 int space; 1040 1041 pipelock(wpipe, 0); 1042 if (wpipe->pipe_state & PIPE_EOF) { 1043 pipeunlock(wpipe); 1044 error = EPIPE; 1045 break; 1046 } 1047 #ifndef PIPE_NODIRECT 1048 /* 1049 * If the transfer is large, we can gain performance if 1050 * we do process-to-process copies directly. 1051 * If the write is non-blocking, we don't use the 1052 * direct write mechanism. 1053 * 1054 * The direct write mechanism will detect the reader going 1055 * away on us. 1056 */ 1057 if (uio->uio_segflg == UIO_USERSPACE && 1058 uio->uio_iov->iov_len >= PIPE_MINDIRECT && 1059 wpipe->pipe_buffer.size >= PIPE_MINDIRECT && 1060 (fp->f_flag & FNONBLOCK) == 0) { 1061 pipeunlock(wpipe); 1062 error = pipe_direct_write(wpipe, uio); 1063 if (error) 1064 break; 1065 continue; 1066 } 1067 #endif 1068 1069 /* 1070 * Pipe buffered writes cannot be coincidental with 1071 * direct writes. We wait until the currently executing 1072 * direct write is completed before we start filling the 1073 * pipe buffer. We break out if a signal occurs or the 1074 * reader goes away. 1075 */ 1076 if (wpipe->pipe_state & PIPE_DIRECTW) { 1077 if (wpipe->pipe_state & PIPE_WANTR) { 1078 wpipe->pipe_state &= ~PIPE_WANTR; 1079 wakeup(wpipe); 1080 } 1081 pipeselwakeup(wpipe); 1082 wpipe->pipe_state |= PIPE_WANTW; 1083 pipeunlock(wpipe); 1084 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH, 1085 "pipbww", 0); 1086 if (error) 1087 break; 1088 else 1089 continue; 1090 } 1091 1092 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1093 1094 /* Writes of size <= PIPE_BUF must be atomic. */ 1095 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 1096 space = 0; 1097 1098 if (space > 0) { 1099 int size; /* Transfer size */ 1100 int segsize; /* first segment to transfer */ 1101 1102 /* 1103 * Transfer size is minimum of uio transfer 1104 * and free space in pipe buffer. 1105 */ 1106 if (space > uio->uio_resid) 1107 size = uio->uio_resid; 1108 else 1109 size = space; 1110 /* 1111 * First segment to transfer is minimum of 1112 * transfer size and contiguous space in 1113 * pipe buffer. If first segment to transfer 1114 * is less than the transfer size, we've got 1115 * a wraparound in the buffer. 1116 */ 1117 segsize = wpipe->pipe_buffer.size - 1118 wpipe->pipe_buffer.in; 1119 if (segsize > size) 1120 segsize = size; 1121 1122 /* Transfer first segment */ 1123 1124 PIPE_UNLOCK(rpipe); 1125 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 1126 segsize, uio); 1127 PIPE_LOCK(rpipe); 1128 1129 if (error == 0 && segsize < size) { 1130 KASSERT(wpipe->pipe_buffer.in + segsize == 1131 wpipe->pipe_buffer.size, 1132 ("Pipe buffer wraparound disappeared")); 1133 /* 1134 * Transfer remaining part now, to 1135 * support atomic writes. Wraparound 1136 * happened. 1137 */ 1138 1139 PIPE_UNLOCK(rpipe); 1140 error = uiomove( 1141 &wpipe->pipe_buffer.buffer[0], 1142 size - segsize, uio); 1143 PIPE_LOCK(rpipe); 1144 } 1145 if (error == 0) { 1146 wpipe->pipe_buffer.in += size; 1147 if (wpipe->pipe_buffer.in >= 1148 wpipe->pipe_buffer.size) { 1149 KASSERT(wpipe->pipe_buffer.in == 1150 size - segsize + 1151 wpipe->pipe_buffer.size, 1152 ("Expected wraparound bad")); 1153 wpipe->pipe_buffer.in = size - segsize; 1154 } 1155 1156 wpipe->pipe_buffer.cnt += size; 1157 KASSERT(wpipe->pipe_buffer.cnt <= 1158 wpipe->pipe_buffer.size, 1159 ("Pipe buffer overflow")); 1160 } 1161 pipeunlock(wpipe); 1162 if (error != 0) 1163 break; 1164 } else { 1165 /* 1166 * If the "read-side" has been blocked, wake it up now. 1167 */ 1168 if (wpipe->pipe_state & PIPE_WANTR) { 1169 wpipe->pipe_state &= ~PIPE_WANTR; 1170 wakeup(wpipe); 1171 } 1172 1173 /* 1174 * don't block on non-blocking I/O 1175 */ 1176 if (fp->f_flag & FNONBLOCK) { 1177 error = EAGAIN; 1178 pipeunlock(wpipe); 1179 break; 1180 } 1181 1182 /* 1183 * We have no more space and have something to offer, 1184 * wake up select/poll. 1185 */ 1186 pipeselwakeup(wpipe); 1187 1188 wpipe->pipe_state |= PIPE_WANTW; 1189 pipeunlock(wpipe); 1190 error = msleep(wpipe, PIPE_MTX(rpipe), 1191 PRIBIO | PCATCH, "pipewr", 0); 1192 if (error != 0) 1193 break; 1194 } 1195 } 1196 1197 pipelock(wpipe, 0); 1198 --wpipe->pipe_busy; 1199 1200 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 1201 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 1202 wakeup(wpipe); 1203 } else if (wpipe->pipe_buffer.cnt > 0) { 1204 /* 1205 * If we have put any characters in the buffer, we wake up 1206 * the reader. 1207 */ 1208 if (wpipe->pipe_state & PIPE_WANTR) { 1209 wpipe->pipe_state &= ~PIPE_WANTR; 1210 wakeup(wpipe); 1211 } 1212 } 1213 1214 /* 1215 * Don't return EPIPE if I/O was successful 1216 */ 1217 if ((wpipe->pipe_buffer.cnt == 0) && 1218 (uio->uio_resid == 0) && 1219 (error == EPIPE)) { 1220 error = 0; 1221 } 1222 1223 if (error == 0) 1224 vfs_timestamp(&wpipe->pipe_mtime); 1225 1226 /* 1227 * We have something to offer, 1228 * wake up select/poll. 1229 */ 1230 if (wpipe->pipe_buffer.cnt) 1231 pipeselwakeup(wpipe); 1232 1233 pipeunlock(wpipe); 1234 PIPE_UNLOCK(rpipe); 1235 return (error); 1236 } 1237 1238 /* ARGSUSED */ 1239 static int 1240 pipe_truncate(fp, length, active_cred, td) 1241 struct file *fp; 1242 off_t length; 1243 struct ucred *active_cred; 1244 struct thread *td; 1245 { 1246 1247 return (EINVAL); 1248 } 1249 1250 /* 1251 * we implement a very minimal set of ioctls for compatibility with sockets. 1252 */ 1253 static int 1254 pipe_ioctl(fp, cmd, data, active_cred, td) 1255 struct file *fp; 1256 u_long cmd; 1257 void *data; 1258 struct ucred *active_cred; 1259 struct thread *td; 1260 { 1261 struct pipe *mpipe = fp->f_data; 1262 int error; 1263 1264 PIPE_LOCK(mpipe); 1265 1266 #ifdef MAC 1267 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data); 1268 if (error) { 1269 PIPE_UNLOCK(mpipe); 1270 return (error); 1271 } 1272 #endif 1273 1274 error = 0; 1275 switch (cmd) { 1276 1277 case FIONBIO: 1278 break; 1279 1280 case FIOASYNC: 1281 if (*(int *)data) { 1282 mpipe->pipe_state |= PIPE_ASYNC; 1283 } else { 1284 mpipe->pipe_state &= ~PIPE_ASYNC; 1285 } 1286 break; 1287 1288 case FIONREAD: 1289 if (mpipe->pipe_state & PIPE_DIRECTW) 1290 *(int *)data = mpipe->pipe_map.cnt; 1291 else 1292 *(int *)data = mpipe->pipe_buffer.cnt; 1293 break; 1294 1295 case FIOSETOWN: 1296 PIPE_UNLOCK(mpipe); 1297 error = fsetown(*(int *)data, &mpipe->pipe_sigio); 1298 goto out_unlocked; 1299 1300 case FIOGETOWN: 1301 *(int *)data = fgetown(&mpipe->pipe_sigio); 1302 break; 1303 1304 /* This is deprecated, FIOSETOWN should be used instead. */ 1305 case TIOCSPGRP: 1306 PIPE_UNLOCK(mpipe); 1307 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio); 1308 goto out_unlocked; 1309 1310 /* This is deprecated, FIOGETOWN should be used instead. */ 1311 case TIOCGPGRP: 1312 *(int *)data = -fgetown(&mpipe->pipe_sigio); 1313 break; 1314 1315 default: 1316 error = ENOTTY; 1317 break; 1318 } 1319 PIPE_UNLOCK(mpipe); 1320 out_unlocked: 1321 return (error); 1322 } 1323 1324 static int 1325 pipe_poll(fp, events, active_cred, td) 1326 struct file *fp; 1327 int events; 1328 struct ucred *active_cred; 1329 struct thread *td; 1330 { 1331 struct pipe *rpipe = fp->f_data; 1332 struct pipe *wpipe; 1333 int revents = 0; 1334 #ifdef MAC 1335 int error; 1336 #endif 1337 1338 wpipe = rpipe->pipe_peer; 1339 PIPE_LOCK(rpipe); 1340 #ifdef MAC 1341 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair); 1342 if (error) 1343 goto locked_error; 1344 #endif 1345 if (events & (POLLIN | POLLRDNORM)) 1346 if ((rpipe->pipe_state & PIPE_DIRECTW) || 1347 (rpipe->pipe_buffer.cnt > 0)) 1348 revents |= events & (POLLIN | POLLRDNORM); 1349 1350 if (events & (POLLOUT | POLLWRNORM)) 1351 if (wpipe->pipe_present != PIPE_ACTIVE || 1352 (wpipe->pipe_state & PIPE_EOF) || 1353 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) && 1354 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF || 1355 wpipe->pipe_buffer.size == 0))) 1356 revents |= events & (POLLOUT | POLLWRNORM); 1357 1358 if ((events & POLLINIGNEOF) == 0) { 1359 if (rpipe->pipe_state & PIPE_EOF) { 1360 revents |= (events & (POLLIN | POLLRDNORM)); 1361 if (wpipe->pipe_present != PIPE_ACTIVE || 1362 (wpipe->pipe_state & PIPE_EOF)) 1363 revents |= POLLHUP; 1364 } 1365 } 1366 1367 if (revents == 0) { 1368 if (events & (POLLIN | POLLRDNORM)) { 1369 selrecord(td, &rpipe->pipe_sel); 1370 if (SEL_WAITING(&rpipe->pipe_sel)) 1371 rpipe->pipe_state |= PIPE_SEL; 1372 } 1373 1374 if (events & (POLLOUT | POLLWRNORM)) { 1375 selrecord(td, &wpipe->pipe_sel); 1376 if (SEL_WAITING(&wpipe->pipe_sel)) 1377 wpipe->pipe_state |= PIPE_SEL; 1378 } 1379 } 1380 #ifdef MAC 1381 locked_error: 1382 #endif 1383 PIPE_UNLOCK(rpipe); 1384 1385 return (revents); 1386 } 1387 1388 /* 1389 * We shouldn't need locks here as we're doing a read and this should 1390 * be a natural race. 1391 */ 1392 static int 1393 pipe_stat(fp, ub, active_cred, td) 1394 struct file *fp; 1395 struct stat *ub; 1396 struct ucred *active_cred; 1397 struct thread *td; 1398 { 1399 struct pipe *pipe; 1400 int new_unr; 1401 #ifdef MAC 1402 int error; 1403 #endif 1404 1405 pipe = fp->f_data; 1406 PIPE_LOCK(pipe); 1407 #ifdef MAC 1408 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair); 1409 if (error) { 1410 PIPE_UNLOCK(pipe); 1411 return (error); 1412 } 1413 #endif 1414 /* 1415 * Lazily allocate an inode number for the pipe. Most pipe 1416 * users do not call fstat(2) on the pipe, which means that 1417 * postponing the inode allocation until it is must be 1418 * returned to userland is useful. If alloc_unr failed, 1419 * assign st_ino zero instead of returning an error. 1420 * Special pipe_ino values: 1421 * -1 - not yet initialized; 1422 * 0 - alloc_unr failed, return 0 as st_ino forever. 1423 */ 1424 if (pipe->pipe_ino == (ino_t)-1) { 1425 new_unr = alloc_unr(pipeino_unr); 1426 if (new_unr != -1) 1427 pipe->pipe_ino = new_unr; 1428 else 1429 pipe->pipe_ino = 0; 1430 } 1431 PIPE_UNLOCK(pipe); 1432 1433 bzero(ub, sizeof(*ub)); 1434 ub->st_mode = S_IFIFO; 1435 ub->st_blksize = PAGE_SIZE; 1436 if (pipe->pipe_state & PIPE_DIRECTW) 1437 ub->st_size = pipe->pipe_map.cnt; 1438 else 1439 ub->st_size = pipe->pipe_buffer.cnt; 1440 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize; 1441 ub->st_atim = pipe->pipe_atime; 1442 ub->st_mtim = pipe->pipe_mtime; 1443 ub->st_ctim = pipe->pipe_ctime; 1444 ub->st_uid = fp->f_cred->cr_uid; 1445 ub->st_gid = fp->f_cred->cr_gid; 1446 ub->st_dev = pipedev_ino; 1447 ub->st_ino = pipe->pipe_ino; 1448 /* 1449 * Left as 0: st_nlink, st_rdev, st_flags, st_gen. 1450 */ 1451 return (0); 1452 } 1453 1454 /* ARGSUSED */ 1455 static int 1456 pipe_close(fp, td) 1457 struct file *fp; 1458 struct thread *td; 1459 { 1460 struct pipe *cpipe = fp->f_data; 1461 1462 fp->f_ops = &badfileops; 1463 fp->f_data = NULL; 1464 funsetown(&cpipe->pipe_sigio); 1465 pipeclose(cpipe); 1466 return (0); 1467 } 1468 1469 static void 1470 pipe_free_kmem(cpipe) 1471 struct pipe *cpipe; 1472 { 1473 1474 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), 1475 ("pipe_free_kmem: pipe mutex locked")); 1476 1477 if (cpipe->pipe_buffer.buffer != NULL) { 1478 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size); 1479 vm_map_remove(pipe_map, 1480 (vm_offset_t)cpipe->pipe_buffer.buffer, 1481 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size); 1482 cpipe->pipe_buffer.buffer = NULL; 1483 } 1484 #ifndef PIPE_NODIRECT 1485 { 1486 cpipe->pipe_map.cnt = 0; 1487 cpipe->pipe_map.pos = 0; 1488 cpipe->pipe_map.npages = 0; 1489 } 1490 #endif 1491 } 1492 1493 /* 1494 * shutdown the pipe 1495 */ 1496 static void 1497 pipeclose(cpipe) 1498 struct pipe *cpipe; 1499 { 1500 struct pipepair *pp; 1501 struct pipe *ppipe; 1502 ino_t ino; 1503 1504 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL")); 1505 1506 PIPE_LOCK(cpipe); 1507 pipelock(cpipe, 0); 1508 pp = cpipe->pipe_pair; 1509 1510 pipeselwakeup(cpipe); 1511 1512 /* 1513 * If the other side is blocked, wake it up saying that 1514 * we want to close it down. 1515 */ 1516 cpipe->pipe_state |= PIPE_EOF; 1517 while (cpipe->pipe_busy) { 1518 wakeup(cpipe); 1519 cpipe->pipe_state |= PIPE_WANT; 1520 pipeunlock(cpipe); 1521 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0); 1522 pipelock(cpipe, 0); 1523 } 1524 1525 1526 /* 1527 * Disconnect from peer, if any. 1528 */ 1529 ppipe = cpipe->pipe_peer; 1530 if (ppipe->pipe_present == PIPE_ACTIVE) { 1531 pipeselwakeup(ppipe); 1532 1533 ppipe->pipe_state |= PIPE_EOF; 1534 wakeup(ppipe); 1535 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0); 1536 } 1537 1538 /* 1539 * Mark this endpoint as free. Release kmem resources. We 1540 * don't mark this endpoint as unused until we've finished 1541 * doing that, or the pipe might disappear out from under 1542 * us. 1543 */ 1544 PIPE_UNLOCK(cpipe); 1545 pipe_free_kmem(cpipe); 1546 PIPE_LOCK(cpipe); 1547 cpipe->pipe_present = PIPE_CLOSING; 1548 pipeunlock(cpipe); 1549 1550 /* 1551 * knlist_clear() may sleep dropping the PIPE_MTX. Set the 1552 * PIPE_FINALIZED, that allows other end to free the 1553 * pipe_pair, only after the knotes are completely dismantled. 1554 */ 1555 knlist_clear(&cpipe->pipe_sel.si_note, 1); 1556 cpipe->pipe_present = PIPE_FINALIZED; 1557 seldrain(&cpipe->pipe_sel); 1558 knlist_destroy(&cpipe->pipe_sel.si_note); 1559 1560 /* 1561 * Postpone the destroy of the fake inode number allocated for 1562 * our end, until pipe mtx is unlocked. 1563 */ 1564 ino = cpipe->pipe_ino; 1565 1566 /* 1567 * If both endpoints are now closed, release the memory for the 1568 * pipe pair. If not, unlock. 1569 */ 1570 if (ppipe->pipe_present == PIPE_FINALIZED) { 1571 PIPE_UNLOCK(cpipe); 1572 #ifdef MAC 1573 mac_pipe_destroy(pp); 1574 #endif 1575 uma_zfree(pipe_zone, cpipe->pipe_pair); 1576 } else 1577 PIPE_UNLOCK(cpipe); 1578 1579 if (ino != 0 && ino != (ino_t)-1) 1580 free_unr(pipeino_unr, ino); 1581 } 1582 1583 /*ARGSUSED*/ 1584 static int 1585 pipe_kqfilter(struct file *fp, struct knote *kn) 1586 { 1587 struct pipe *cpipe; 1588 1589 cpipe = kn->kn_fp->f_data; 1590 PIPE_LOCK(cpipe); 1591 switch (kn->kn_filter) { 1592 case EVFILT_READ: 1593 kn->kn_fop = &pipe_rfiltops; 1594 break; 1595 case EVFILT_WRITE: 1596 kn->kn_fop = &pipe_wfiltops; 1597 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) { 1598 /* other end of pipe has been closed */ 1599 PIPE_UNLOCK(cpipe); 1600 return (EPIPE); 1601 } 1602 cpipe = cpipe->pipe_peer; 1603 break; 1604 default: 1605 PIPE_UNLOCK(cpipe); 1606 return (EINVAL); 1607 } 1608 1609 knlist_add(&cpipe->pipe_sel.si_note, kn, 1); 1610 PIPE_UNLOCK(cpipe); 1611 return (0); 1612 } 1613 1614 static void 1615 filt_pipedetach(struct knote *kn) 1616 { 1617 struct pipe *cpipe = (struct pipe *)kn->kn_fp->f_data; 1618 1619 PIPE_LOCK(cpipe); 1620 if (kn->kn_filter == EVFILT_WRITE) 1621 cpipe = cpipe->pipe_peer; 1622 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1); 1623 PIPE_UNLOCK(cpipe); 1624 } 1625 1626 /*ARGSUSED*/ 1627 static int 1628 filt_piperead(struct knote *kn, long hint) 1629 { 1630 struct pipe *rpipe = kn->kn_fp->f_data; 1631 struct pipe *wpipe = rpipe->pipe_peer; 1632 int ret; 1633 1634 PIPE_LOCK(rpipe); 1635 kn->kn_data = rpipe->pipe_buffer.cnt; 1636 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) 1637 kn->kn_data = rpipe->pipe_map.cnt; 1638 1639 if ((rpipe->pipe_state & PIPE_EOF) || 1640 wpipe->pipe_present != PIPE_ACTIVE || 1641 (wpipe->pipe_state & PIPE_EOF)) { 1642 kn->kn_flags |= EV_EOF; 1643 PIPE_UNLOCK(rpipe); 1644 return (1); 1645 } 1646 ret = kn->kn_data > 0; 1647 PIPE_UNLOCK(rpipe); 1648 return ret; 1649 } 1650 1651 /*ARGSUSED*/ 1652 static int 1653 filt_pipewrite(struct knote *kn, long hint) 1654 { 1655 struct pipe *rpipe = kn->kn_fp->f_data; 1656 struct pipe *wpipe = rpipe->pipe_peer; 1657 1658 PIPE_LOCK(rpipe); 1659 if (wpipe->pipe_present != PIPE_ACTIVE || 1660 (wpipe->pipe_state & PIPE_EOF)) { 1661 kn->kn_data = 0; 1662 kn->kn_flags |= EV_EOF; 1663 PIPE_UNLOCK(rpipe); 1664 return (1); 1665 } 1666 kn->kn_data = (wpipe->pipe_buffer.size > 0) ? 1667 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF; 1668 if (wpipe->pipe_state & PIPE_DIRECTW) 1669 kn->kn_data = 0; 1670 1671 PIPE_UNLOCK(rpipe); 1672 return (kn->kn_data >= PIPE_BUF); 1673 }
Cache object: 02e54cd346d30f0d99a2adadb8b61244
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