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/10.0/sys/kern/sys_pipe.c 255426 2013-09-09 18:11:59Z jhb $"); 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 int pipe_create(struct pipe *pipe, int backing); 225 static int 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 int 335 pipe_paircreate(struct thread *td, struct pipepair **p_pp) 336 { 337 struct pipepair *pp; 338 struct pipe *rpipe, *wpipe; 339 int error; 340 341 *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK); 342 #ifdef MAC 343 /* 344 * The MAC label is shared between the connected endpoints. As a 345 * result mac_pipe_init() and mac_pipe_create() are called once 346 * for the pair, and not on the endpoints. 347 */ 348 mac_pipe_init(pp); 349 mac_pipe_create(td->td_ucred, pp); 350 #endif 351 rpipe = &pp->pp_rpipe; 352 wpipe = &pp->pp_wpipe; 353 354 knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe)); 355 knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe)); 356 357 /* Only the forward direction pipe is backed by default */ 358 if ((error = pipe_create(rpipe, 1)) != 0 || 359 (error = pipe_create(wpipe, 0)) != 0) { 360 pipeclose(rpipe); 361 pipeclose(wpipe); 362 return (error); 363 } 364 365 rpipe->pipe_state |= PIPE_DIRECTOK; 366 wpipe->pipe_state |= PIPE_DIRECTOK; 367 return (0); 368 } 369 370 int 371 pipe_named_ctor(struct pipe **ppipe, struct thread *td) 372 { 373 struct pipepair *pp; 374 int error; 375 376 error = pipe_paircreate(td, &pp); 377 if (error != 0) 378 return (error); 379 pp->pp_rpipe.pipe_state |= PIPE_NAMED; 380 *ppipe = &pp->pp_rpipe; 381 return (0); 382 } 383 384 void 385 pipe_dtor(struct pipe *dpipe) 386 { 387 ino_t ino; 388 389 ino = dpipe->pipe_ino; 390 funsetown(&dpipe->pipe_sigio); 391 pipeclose(dpipe); 392 if (dpipe->pipe_state & PIPE_NAMED) { 393 dpipe = dpipe->pipe_peer; 394 funsetown(&dpipe->pipe_sigio); 395 pipeclose(dpipe); 396 } 397 if (ino != 0 && ino != (ino_t)-1) 398 free_unr(pipeino_unr, ino); 399 } 400 401 /* 402 * The pipe system call for the DTYPE_PIPE type of pipes. If we fail, let 403 * the zone pick up the pieces via pipeclose(). 404 */ 405 int 406 kern_pipe(struct thread *td, int fildes[2]) 407 { 408 409 return (kern_pipe2(td, fildes, 0)); 410 } 411 412 int 413 kern_pipe2(struct thread *td, int fildes[2], int flags) 414 { 415 struct filedesc *fdp; 416 struct file *rf, *wf; 417 struct pipe *rpipe, *wpipe; 418 struct pipepair *pp; 419 int fd, fflags, error; 420 421 fdp = td->td_proc->p_fd; 422 error = pipe_paircreate(td, &pp); 423 if (error != 0) 424 return (error); 425 rpipe = &pp->pp_rpipe; 426 wpipe = &pp->pp_wpipe; 427 error = falloc(td, &rf, &fd, flags); 428 if (error) { 429 pipeclose(rpipe); 430 pipeclose(wpipe); 431 return (error); 432 } 433 /* An extra reference on `rf' has been held for us by falloc(). */ 434 fildes[0] = fd; 435 436 fflags = FREAD | FWRITE; 437 if ((flags & O_NONBLOCK) != 0) 438 fflags |= FNONBLOCK; 439 440 /* 441 * Warning: once we've gotten past allocation of the fd for the 442 * read-side, we can only drop the read side via fdrop() in order 443 * to avoid races against processes which manage to dup() the read 444 * side while we are blocked trying to allocate the write side. 445 */ 446 finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops); 447 error = falloc(td, &wf, &fd, flags); 448 if (error) { 449 fdclose(fdp, rf, fildes[0], td); 450 fdrop(rf, td); 451 /* rpipe has been closed by fdrop(). */ 452 pipeclose(wpipe); 453 return (error); 454 } 455 /* An extra reference on `wf' has been held for us by falloc(). */ 456 finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops); 457 fdrop(wf, td); 458 fildes[1] = fd; 459 fdrop(rf, td); 460 461 return (0); 462 } 463 464 /* ARGSUSED */ 465 int 466 sys_pipe(struct thread *td, struct pipe_args *uap) 467 { 468 int error; 469 int fildes[2]; 470 471 error = kern_pipe(td, fildes); 472 if (error) 473 return (error); 474 475 td->td_retval[0] = fildes[0]; 476 td->td_retval[1] = fildes[1]; 477 478 return (0); 479 } 480 481 int 482 sys_pipe2(struct thread *td, struct pipe2_args *uap) 483 { 484 int error, fildes[2]; 485 486 if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK)) 487 return (EINVAL); 488 error = kern_pipe2(td, fildes, uap->flags); 489 if (error) 490 return (error); 491 error = copyout(fildes, uap->fildes, 2 * sizeof(int)); 492 if (error) { 493 (void)kern_close(td, fildes[0]); 494 (void)kern_close(td, fildes[1]); 495 } 496 return (error); 497 } 498 499 /* 500 * Allocate kva for pipe circular buffer, the space is pageable 501 * This routine will 'realloc' the size of a pipe safely, if it fails 502 * it will retain the old buffer. 503 * If it fails it will return ENOMEM. 504 */ 505 static int 506 pipespace_new(cpipe, size) 507 struct pipe *cpipe; 508 int size; 509 { 510 caddr_t buffer; 511 int error, cnt, firstseg; 512 static int curfail = 0; 513 static struct timeval lastfail; 514 515 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked")); 516 KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW), 517 ("pipespace: resize of direct writes not allowed")); 518 retry: 519 cnt = cpipe->pipe_buffer.cnt; 520 if (cnt > size) 521 size = cnt; 522 523 size = round_page(size); 524 buffer = (caddr_t) vm_map_min(pipe_map); 525 526 error = vm_map_find(pipe_map, NULL, 0, 527 (vm_offset_t *) &buffer, size, 0, VMFS_ANY_SPACE, 528 VM_PROT_ALL, VM_PROT_ALL, 0); 529 if (error != KERN_SUCCESS) { 530 if ((cpipe->pipe_buffer.buffer == NULL) && 531 (size > SMALL_PIPE_SIZE)) { 532 size = SMALL_PIPE_SIZE; 533 pipefragretry++; 534 goto retry; 535 } 536 if (cpipe->pipe_buffer.buffer == NULL) { 537 pipeallocfail++; 538 if (ppsratecheck(&lastfail, &curfail, 1)) 539 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n"); 540 } else { 541 piperesizefail++; 542 } 543 return (ENOMEM); 544 } 545 546 /* copy data, then free old resources if we're resizing */ 547 if (cnt > 0) { 548 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) { 549 firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out; 550 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 551 buffer, firstseg); 552 if ((cnt - firstseg) > 0) 553 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg], 554 cpipe->pipe_buffer.in); 555 } else { 556 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 557 buffer, cnt); 558 } 559 } 560 pipe_free_kmem(cpipe); 561 cpipe->pipe_buffer.buffer = buffer; 562 cpipe->pipe_buffer.size = size; 563 cpipe->pipe_buffer.in = cnt; 564 cpipe->pipe_buffer.out = 0; 565 cpipe->pipe_buffer.cnt = cnt; 566 atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size); 567 return (0); 568 } 569 570 /* 571 * Wrapper for pipespace_new() that performs locking assertions. 572 */ 573 static int 574 pipespace(cpipe, size) 575 struct pipe *cpipe; 576 int size; 577 { 578 579 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 580 ("Unlocked pipe passed to pipespace")); 581 return (pipespace_new(cpipe, size)); 582 } 583 584 /* 585 * lock a pipe for I/O, blocking other access 586 */ 587 static __inline int 588 pipelock(cpipe, catch) 589 struct pipe *cpipe; 590 int catch; 591 { 592 int error; 593 594 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 595 while (cpipe->pipe_state & PIPE_LOCKFL) { 596 cpipe->pipe_state |= PIPE_LWANT; 597 error = msleep(cpipe, PIPE_MTX(cpipe), 598 catch ? (PRIBIO | PCATCH) : PRIBIO, 599 "pipelk", 0); 600 if (error != 0) 601 return (error); 602 } 603 cpipe->pipe_state |= PIPE_LOCKFL; 604 return (0); 605 } 606 607 /* 608 * unlock a pipe I/O lock 609 */ 610 static __inline void 611 pipeunlock(cpipe) 612 struct pipe *cpipe; 613 { 614 615 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 616 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 617 ("Unlocked pipe passed to pipeunlock")); 618 cpipe->pipe_state &= ~PIPE_LOCKFL; 619 if (cpipe->pipe_state & PIPE_LWANT) { 620 cpipe->pipe_state &= ~PIPE_LWANT; 621 wakeup(cpipe); 622 } 623 } 624 625 void 626 pipeselwakeup(cpipe) 627 struct pipe *cpipe; 628 { 629 630 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 631 if (cpipe->pipe_state & PIPE_SEL) { 632 selwakeuppri(&cpipe->pipe_sel, PSOCK); 633 if (!SEL_WAITING(&cpipe->pipe_sel)) 634 cpipe->pipe_state &= ~PIPE_SEL; 635 } 636 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) 637 pgsigio(&cpipe->pipe_sigio, SIGIO, 0); 638 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0); 639 } 640 641 /* 642 * Initialize and allocate VM and memory for pipe. The structure 643 * will start out zero'd from the ctor, so we just manage the kmem. 644 */ 645 static int 646 pipe_create(pipe, backing) 647 struct pipe *pipe; 648 int backing; 649 { 650 int error; 651 652 if (backing) { 653 if (amountpipekva > maxpipekva / 2) 654 error = pipespace_new(pipe, SMALL_PIPE_SIZE); 655 else 656 error = pipespace_new(pipe, PIPE_SIZE); 657 } else { 658 /* If we're not backing this pipe, no need to do anything. */ 659 error = 0; 660 } 661 pipe->pipe_ino = -1; 662 return (error); 663 } 664 665 /* ARGSUSED */ 666 static int 667 pipe_read(fp, uio, active_cred, flags, td) 668 struct file *fp; 669 struct uio *uio; 670 struct ucred *active_cred; 671 struct thread *td; 672 int flags; 673 { 674 struct pipe *rpipe; 675 int error; 676 int nread = 0; 677 int size; 678 679 rpipe = fp->f_data; 680 PIPE_LOCK(rpipe); 681 ++rpipe->pipe_busy; 682 error = pipelock(rpipe, 1); 683 if (error) 684 goto unlocked_error; 685 686 #ifdef MAC 687 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair); 688 if (error) 689 goto locked_error; 690 #endif 691 if (amountpipekva > (3 * maxpipekva) / 4) { 692 if (!(rpipe->pipe_state & PIPE_DIRECTW) && 693 (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) && 694 (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) && 695 (piperesizeallowed == 1)) { 696 PIPE_UNLOCK(rpipe); 697 pipespace(rpipe, SMALL_PIPE_SIZE); 698 PIPE_LOCK(rpipe); 699 } 700 } 701 702 while (uio->uio_resid) { 703 /* 704 * normal pipe buffer receive 705 */ 706 if (rpipe->pipe_buffer.cnt > 0) { 707 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 708 if (size > rpipe->pipe_buffer.cnt) 709 size = rpipe->pipe_buffer.cnt; 710 if (size > uio->uio_resid) 711 size = uio->uio_resid; 712 713 PIPE_UNLOCK(rpipe); 714 error = uiomove( 715 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 716 size, uio); 717 PIPE_LOCK(rpipe); 718 if (error) 719 break; 720 721 rpipe->pipe_buffer.out += size; 722 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 723 rpipe->pipe_buffer.out = 0; 724 725 rpipe->pipe_buffer.cnt -= size; 726 727 /* 728 * If there is no more to read in the pipe, reset 729 * its pointers to the beginning. This improves 730 * cache hit stats. 731 */ 732 if (rpipe->pipe_buffer.cnt == 0) { 733 rpipe->pipe_buffer.in = 0; 734 rpipe->pipe_buffer.out = 0; 735 } 736 nread += size; 737 #ifndef PIPE_NODIRECT 738 /* 739 * Direct copy, bypassing a kernel buffer. 740 */ 741 } else if ((size = rpipe->pipe_map.cnt) && 742 (rpipe->pipe_state & PIPE_DIRECTW)) { 743 if (size > uio->uio_resid) 744 size = (u_int) uio->uio_resid; 745 746 PIPE_UNLOCK(rpipe); 747 error = uiomove_fromphys(rpipe->pipe_map.ms, 748 rpipe->pipe_map.pos, size, uio); 749 PIPE_LOCK(rpipe); 750 if (error) 751 break; 752 nread += size; 753 rpipe->pipe_map.pos += size; 754 rpipe->pipe_map.cnt -= size; 755 if (rpipe->pipe_map.cnt == 0) { 756 rpipe->pipe_state &= ~(PIPE_DIRECTW|PIPE_WANTW); 757 wakeup(rpipe); 758 } 759 #endif 760 } else { 761 /* 762 * detect EOF condition 763 * read returns 0 on EOF, no need to set error 764 */ 765 if (rpipe->pipe_state & PIPE_EOF) 766 break; 767 768 /* 769 * If the "write-side" has been blocked, wake it up now. 770 */ 771 if (rpipe->pipe_state & PIPE_WANTW) { 772 rpipe->pipe_state &= ~PIPE_WANTW; 773 wakeup(rpipe); 774 } 775 776 /* 777 * Break if some data was read. 778 */ 779 if (nread > 0) 780 break; 781 782 /* 783 * Unlock the pipe buffer for our remaining processing. 784 * We will either break out with an error or we will 785 * sleep and relock to loop. 786 */ 787 pipeunlock(rpipe); 788 789 /* 790 * Handle non-blocking mode operation or 791 * wait for more data. 792 */ 793 if (fp->f_flag & FNONBLOCK) { 794 error = EAGAIN; 795 } else { 796 rpipe->pipe_state |= PIPE_WANTR; 797 if ((error = msleep(rpipe, PIPE_MTX(rpipe), 798 PRIBIO | PCATCH, 799 "piperd", 0)) == 0) 800 error = pipelock(rpipe, 1); 801 } 802 if (error) 803 goto unlocked_error; 804 } 805 } 806 #ifdef MAC 807 locked_error: 808 #endif 809 pipeunlock(rpipe); 810 811 /* XXX: should probably do this before getting any locks. */ 812 if (error == 0) 813 vfs_timestamp(&rpipe->pipe_atime); 814 unlocked_error: 815 --rpipe->pipe_busy; 816 817 /* 818 * PIPE_WANT processing only makes sense if pipe_busy is 0. 819 */ 820 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 821 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 822 wakeup(rpipe); 823 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 824 /* 825 * Handle write blocking hysteresis. 826 */ 827 if (rpipe->pipe_state & PIPE_WANTW) { 828 rpipe->pipe_state &= ~PIPE_WANTW; 829 wakeup(rpipe); 830 } 831 } 832 833 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF) 834 pipeselwakeup(rpipe); 835 836 PIPE_UNLOCK(rpipe); 837 return (error); 838 } 839 840 #ifndef PIPE_NODIRECT 841 /* 842 * Map the sending processes' buffer into kernel space and wire it. 843 * This is similar to a physical write operation. 844 */ 845 static int 846 pipe_build_write_buffer(wpipe, uio) 847 struct pipe *wpipe; 848 struct uio *uio; 849 { 850 u_int size; 851 int i; 852 853 PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED); 854 KASSERT(wpipe->pipe_state & PIPE_DIRECTW, 855 ("Clone attempt on non-direct write pipe!")); 856 857 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size) 858 size = wpipe->pipe_buffer.size; 859 else 860 size = uio->uio_iov->iov_len; 861 862 if ((i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 863 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ, 864 wpipe->pipe_map.ms, PIPENPAGES)) < 0) 865 return (EFAULT); 866 867 /* 868 * set up the control block 869 */ 870 wpipe->pipe_map.npages = i; 871 wpipe->pipe_map.pos = 872 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 873 wpipe->pipe_map.cnt = size; 874 875 /* 876 * and update the uio data 877 */ 878 879 uio->uio_iov->iov_len -= size; 880 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size; 881 if (uio->uio_iov->iov_len == 0) 882 uio->uio_iov++; 883 uio->uio_resid -= size; 884 uio->uio_offset += size; 885 return (0); 886 } 887 888 /* 889 * unmap and unwire the process buffer 890 */ 891 static void 892 pipe_destroy_write_buffer(wpipe) 893 struct pipe *wpipe; 894 { 895 896 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 897 vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages); 898 wpipe->pipe_map.npages = 0; 899 } 900 901 /* 902 * In the case of a signal, the writing process might go away. This 903 * code copies the data into the circular buffer so that the source 904 * pages can be freed without loss of data. 905 */ 906 static void 907 pipe_clone_write_buffer(wpipe) 908 struct pipe *wpipe; 909 { 910 struct uio uio; 911 struct iovec iov; 912 int size; 913 int pos; 914 915 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 916 size = wpipe->pipe_map.cnt; 917 pos = wpipe->pipe_map.pos; 918 919 wpipe->pipe_buffer.in = size; 920 wpipe->pipe_buffer.out = 0; 921 wpipe->pipe_buffer.cnt = size; 922 wpipe->pipe_state &= ~PIPE_DIRECTW; 923 924 PIPE_UNLOCK(wpipe); 925 iov.iov_base = wpipe->pipe_buffer.buffer; 926 iov.iov_len = size; 927 uio.uio_iov = &iov; 928 uio.uio_iovcnt = 1; 929 uio.uio_offset = 0; 930 uio.uio_resid = size; 931 uio.uio_segflg = UIO_SYSSPACE; 932 uio.uio_rw = UIO_READ; 933 uio.uio_td = curthread; 934 uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio); 935 PIPE_LOCK(wpipe); 936 pipe_destroy_write_buffer(wpipe); 937 } 938 939 /* 940 * This implements the pipe buffer write mechanism. Note that only 941 * a direct write OR a normal pipe write can be pending at any given time. 942 * If there are any characters in the pipe buffer, the direct write will 943 * be deferred until the receiving process grabs all of the bytes from 944 * the pipe buffer. Then the direct mapping write is set-up. 945 */ 946 static int 947 pipe_direct_write(wpipe, uio) 948 struct pipe *wpipe; 949 struct uio *uio; 950 { 951 int error; 952 953 retry: 954 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 955 error = pipelock(wpipe, 1); 956 if (wpipe->pipe_state & PIPE_EOF) 957 error = EPIPE; 958 if (error) { 959 pipeunlock(wpipe); 960 goto error1; 961 } 962 while (wpipe->pipe_state & PIPE_DIRECTW) { 963 if (wpipe->pipe_state & PIPE_WANTR) { 964 wpipe->pipe_state &= ~PIPE_WANTR; 965 wakeup(wpipe); 966 } 967 pipeselwakeup(wpipe); 968 wpipe->pipe_state |= PIPE_WANTW; 969 pipeunlock(wpipe); 970 error = msleep(wpipe, PIPE_MTX(wpipe), 971 PRIBIO | PCATCH, "pipdww", 0); 972 if (error) 973 goto error1; 974 else 975 goto retry; 976 } 977 wpipe->pipe_map.cnt = 0; /* transfer not ready yet */ 978 if (wpipe->pipe_buffer.cnt > 0) { 979 if (wpipe->pipe_state & PIPE_WANTR) { 980 wpipe->pipe_state &= ~PIPE_WANTR; 981 wakeup(wpipe); 982 } 983 pipeselwakeup(wpipe); 984 wpipe->pipe_state |= PIPE_WANTW; 985 pipeunlock(wpipe); 986 error = msleep(wpipe, PIPE_MTX(wpipe), 987 PRIBIO | PCATCH, "pipdwc", 0); 988 if (error) 989 goto error1; 990 else 991 goto retry; 992 } 993 994 wpipe->pipe_state |= PIPE_DIRECTW; 995 996 PIPE_UNLOCK(wpipe); 997 error = pipe_build_write_buffer(wpipe, uio); 998 PIPE_LOCK(wpipe); 999 if (error) { 1000 wpipe->pipe_state &= ~PIPE_DIRECTW; 1001 pipeunlock(wpipe); 1002 goto error1; 1003 } 1004 1005 error = 0; 1006 while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) { 1007 if (wpipe->pipe_state & PIPE_EOF) { 1008 pipe_destroy_write_buffer(wpipe); 1009 pipeselwakeup(wpipe); 1010 pipeunlock(wpipe); 1011 error = EPIPE; 1012 goto error1; 1013 } 1014 if (wpipe->pipe_state & PIPE_WANTR) { 1015 wpipe->pipe_state &= ~PIPE_WANTR; 1016 wakeup(wpipe); 1017 } 1018 pipeselwakeup(wpipe); 1019 wpipe->pipe_state |= PIPE_WANTW; 1020 pipeunlock(wpipe); 1021 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH, 1022 "pipdwt", 0); 1023 pipelock(wpipe, 0); 1024 } 1025 1026 if (wpipe->pipe_state & PIPE_EOF) 1027 error = EPIPE; 1028 if (wpipe->pipe_state & PIPE_DIRECTW) { 1029 /* 1030 * this bit of trickery substitutes a kernel buffer for 1031 * the process that might be going away. 1032 */ 1033 pipe_clone_write_buffer(wpipe); 1034 } else { 1035 pipe_destroy_write_buffer(wpipe); 1036 } 1037 pipeunlock(wpipe); 1038 return (error); 1039 1040 error1: 1041 wakeup(wpipe); 1042 return (error); 1043 } 1044 #endif 1045 1046 static int 1047 pipe_write(fp, uio, active_cred, flags, td) 1048 struct file *fp; 1049 struct uio *uio; 1050 struct ucred *active_cred; 1051 struct thread *td; 1052 int flags; 1053 { 1054 int error = 0; 1055 int desiredsize; 1056 ssize_t orig_resid; 1057 struct pipe *wpipe, *rpipe; 1058 1059 rpipe = fp->f_data; 1060 wpipe = PIPE_PEER(rpipe); 1061 PIPE_LOCK(rpipe); 1062 error = pipelock(wpipe, 1); 1063 if (error) { 1064 PIPE_UNLOCK(rpipe); 1065 return (error); 1066 } 1067 /* 1068 * detect loss of pipe read side, issue SIGPIPE if lost. 1069 */ 1070 if (wpipe->pipe_present != PIPE_ACTIVE || 1071 (wpipe->pipe_state & PIPE_EOF)) { 1072 pipeunlock(wpipe); 1073 PIPE_UNLOCK(rpipe); 1074 return (EPIPE); 1075 } 1076 #ifdef MAC 1077 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair); 1078 if (error) { 1079 pipeunlock(wpipe); 1080 PIPE_UNLOCK(rpipe); 1081 return (error); 1082 } 1083 #endif 1084 ++wpipe->pipe_busy; 1085 1086 /* Choose a larger size if it's advantageous */ 1087 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size); 1088 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) { 1089 if (piperesizeallowed != 1) 1090 break; 1091 if (amountpipekva > maxpipekva / 2) 1092 break; 1093 if (desiredsize == BIG_PIPE_SIZE) 1094 break; 1095 desiredsize = desiredsize * 2; 1096 } 1097 1098 /* Choose a smaller size if we're in a OOM situation */ 1099 if ((amountpipekva > (3 * maxpipekva) / 4) && 1100 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) && 1101 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) && 1102 (piperesizeallowed == 1)) 1103 desiredsize = SMALL_PIPE_SIZE; 1104 1105 /* Resize if the above determined that a new size was necessary */ 1106 if ((desiredsize != wpipe->pipe_buffer.size) && 1107 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) { 1108 PIPE_UNLOCK(wpipe); 1109 pipespace(wpipe, desiredsize); 1110 PIPE_LOCK(wpipe); 1111 } 1112 if (wpipe->pipe_buffer.size == 0) { 1113 /* 1114 * This can only happen for reverse direction use of pipes 1115 * in a complete OOM situation. 1116 */ 1117 error = ENOMEM; 1118 --wpipe->pipe_busy; 1119 pipeunlock(wpipe); 1120 PIPE_UNLOCK(wpipe); 1121 return (error); 1122 } 1123 1124 pipeunlock(wpipe); 1125 1126 orig_resid = uio->uio_resid; 1127 1128 while (uio->uio_resid) { 1129 int space; 1130 1131 pipelock(wpipe, 0); 1132 if (wpipe->pipe_state & PIPE_EOF) { 1133 pipeunlock(wpipe); 1134 error = EPIPE; 1135 break; 1136 } 1137 #ifndef PIPE_NODIRECT 1138 /* 1139 * If the transfer is large, we can gain performance if 1140 * we do process-to-process copies directly. 1141 * If the write is non-blocking, we don't use the 1142 * direct write mechanism. 1143 * 1144 * The direct write mechanism will detect the reader going 1145 * away on us. 1146 */ 1147 if (uio->uio_segflg == UIO_USERSPACE && 1148 uio->uio_iov->iov_len >= PIPE_MINDIRECT && 1149 wpipe->pipe_buffer.size >= PIPE_MINDIRECT && 1150 (fp->f_flag & FNONBLOCK) == 0) { 1151 pipeunlock(wpipe); 1152 error = pipe_direct_write(wpipe, uio); 1153 if (error) 1154 break; 1155 continue; 1156 } 1157 #endif 1158 1159 /* 1160 * Pipe buffered writes cannot be coincidental with 1161 * direct writes. We wait until the currently executing 1162 * direct write is completed before we start filling the 1163 * pipe buffer. We break out if a signal occurs or the 1164 * reader goes away. 1165 */ 1166 if (wpipe->pipe_state & PIPE_DIRECTW) { 1167 if (wpipe->pipe_state & PIPE_WANTR) { 1168 wpipe->pipe_state &= ~PIPE_WANTR; 1169 wakeup(wpipe); 1170 } 1171 pipeselwakeup(wpipe); 1172 wpipe->pipe_state |= PIPE_WANTW; 1173 pipeunlock(wpipe); 1174 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH, 1175 "pipbww", 0); 1176 if (error) 1177 break; 1178 else 1179 continue; 1180 } 1181 1182 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1183 1184 /* Writes of size <= PIPE_BUF must be atomic. */ 1185 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 1186 space = 0; 1187 1188 if (space > 0) { 1189 int size; /* Transfer size */ 1190 int segsize; /* first segment to transfer */ 1191 1192 /* 1193 * Transfer size is minimum of uio transfer 1194 * and free space in pipe buffer. 1195 */ 1196 if (space > uio->uio_resid) 1197 size = uio->uio_resid; 1198 else 1199 size = space; 1200 /* 1201 * First segment to transfer is minimum of 1202 * transfer size and contiguous space in 1203 * pipe buffer. If first segment to transfer 1204 * is less than the transfer size, we've got 1205 * a wraparound in the buffer. 1206 */ 1207 segsize = wpipe->pipe_buffer.size - 1208 wpipe->pipe_buffer.in; 1209 if (segsize > size) 1210 segsize = size; 1211 1212 /* Transfer first segment */ 1213 1214 PIPE_UNLOCK(rpipe); 1215 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 1216 segsize, uio); 1217 PIPE_LOCK(rpipe); 1218 1219 if (error == 0 && segsize < size) { 1220 KASSERT(wpipe->pipe_buffer.in + segsize == 1221 wpipe->pipe_buffer.size, 1222 ("Pipe buffer wraparound disappeared")); 1223 /* 1224 * Transfer remaining part now, to 1225 * support atomic writes. Wraparound 1226 * happened. 1227 */ 1228 1229 PIPE_UNLOCK(rpipe); 1230 error = uiomove( 1231 &wpipe->pipe_buffer.buffer[0], 1232 size - segsize, uio); 1233 PIPE_LOCK(rpipe); 1234 } 1235 if (error == 0) { 1236 wpipe->pipe_buffer.in += size; 1237 if (wpipe->pipe_buffer.in >= 1238 wpipe->pipe_buffer.size) { 1239 KASSERT(wpipe->pipe_buffer.in == 1240 size - segsize + 1241 wpipe->pipe_buffer.size, 1242 ("Expected wraparound bad")); 1243 wpipe->pipe_buffer.in = size - segsize; 1244 } 1245 1246 wpipe->pipe_buffer.cnt += size; 1247 KASSERT(wpipe->pipe_buffer.cnt <= 1248 wpipe->pipe_buffer.size, 1249 ("Pipe buffer overflow")); 1250 } 1251 pipeunlock(wpipe); 1252 if (error != 0) 1253 break; 1254 } else { 1255 /* 1256 * If the "read-side" has been blocked, wake it up now. 1257 */ 1258 if (wpipe->pipe_state & PIPE_WANTR) { 1259 wpipe->pipe_state &= ~PIPE_WANTR; 1260 wakeup(wpipe); 1261 } 1262 1263 /* 1264 * don't block on non-blocking I/O 1265 */ 1266 if (fp->f_flag & FNONBLOCK) { 1267 error = EAGAIN; 1268 pipeunlock(wpipe); 1269 break; 1270 } 1271 1272 /* 1273 * We have no more space and have something to offer, 1274 * wake up select/poll. 1275 */ 1276 pipeselwakeup(wpipe); 1277 1278 wpipe->pipe_state |= PIPE_WANTW; 1279 pipeunlock(wpipe); 1280 error = msleep(wpipe, PIPE_MTX(rpipe), 1281 PRIBIO | PCATCH, "pipewr", 0); 1282 if (error != 0) 1283 break; 1284 } 1285 } 1286 1287 pipelock(wpipe, 0); 1288 --wpipe->pipe_busy; 1289 1290 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 1291 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 1292 wakeup(wpipe); 1293 } else if (wpipe->pipe_buffer.cnt > 0) { 1294 /* 1295 * If we have put any characters in the buffer, we wake up 1296 * the reader. 1297 */ 1298 if (wpipe->pipe_state & PIPE_WANTR) { 1299 wpipe->pipe_state &= ~PIPE_WANTR; 1300 wakeup(wpipe); 1301 } 1302 } 1303 1304 /* 1305 * Don't return EPIPE if I/O was successful 1306 */ 1307 if ((wpipe->pipe_buffer.cnt == 0) && 1308 (uio->uio_resid == 0) && 1309 (error == EPIPE)) { 1310 error = 0; 1311 } 1312 1313 if (error == 0) 1314 vfs_timestamp(&wpipe->pipe_mtime); 1315 1316 /* 1317 * We have something to offer, 1318 * wake up select/poll. 1319 */ 1320 if (wpipe->pipe_buffer.cnt) 1321 pipeselwakeup(wpipe); 1322 1323 pipeunlock(wpipe); 1324 PIPE_UNLOCK(rpipe); 1325 return (error); 1326 } 1327 1328 /* ARGSUSED */ 1329 static int 1330 pipe_truncate(fp, length, active_cred, td) 1331 struct file *fp; 1332 off_t length; 1333 struct ucred *active_cred; 1334 struct thread *td; 1335 { 1336 1337 /* For named pipes call the vnode operation. */ 1338 if (fp->f_vnode != NULL) 1339 return (vnops.fo_truncate(fp, length, active_cred, td)); 1340 return (EINVAL); 1341 } 1342 1343 /* 1344 * we implement a very minimal set of ioctls for compatibility with sockets. 1345 */ 1346 static int 1347 pipe_ioctl(fp, cmd, data, active_cred, td) 1348 struct file *fp; 1349 u_long cmd; 1350 void *data; 1351 struct ucred *active_cred; 1352 struct thread *td; 1353 { 1354 struct pipe *mpipe = fp->f_data; 1355 int error; 1356 1357 PIPE_LOCK(mpipe); 1358 1359 #ifdef MAC 1360 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data); 1361 if (error) { 1362 PIPE_UNLOCK(mpipe); 1363 return (error); 1364 } 1365 #endif 1366 1367 error = 0; 1368 switch (cmd) { 1369 1370 case FIONBIO: 1371 break; 1372 1373 case FIOASYNC: 1374 if (*(int *)data) { 1375 mpipe->pipe_state |= PIPE_ASYNC; 1376 } else { 1377 mpipe->pipe_state &= ~PIPE_ASYNC; 1378 } 1379 break; 1380 1381 case FIONREAD: 1382 if (!(fp->f_flag & FREAD)) { 1383 *(int *)data = 0; 1384 PIPE_UNLOCK(mpipe); 1385 return (0); 1386 } 1387 if (mpipe->pipe_state & PIPE_DIRECTW) 1388 *(int *)data = mpipe->pipe_map.cnt; 1389 else 1390 *(int *)data = mpipe->pipe_buffer.cnt; 1391 break; 1392 1393 case FIOSETOWN: 1394 PIPE_UNLOCK(mpipe); 1395 error = fsetown(*(int *)data, &mpipe->pipe_sigio); 1396 goto out_unlocked; 1397 1398 case FIOGETOWN: 1399 *(int *)data = fgetown(&mpipe->pipe_sigio); 1400 break; 1401 1402 /* This is deprecated, FIOSETOWN should be used instead. */ 1403 case TIOCSPGRP: 1404 PIPE_UNLOCK(mpipe); 1405 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio); 1406 goto out_unlocked; 1407 1408 /* This is deprecated, FIOGETOWN should be used instead. */ 1409 case TIOCGPGRP: 1410 *(int *)data = -fgetown(&mpipe->pipe_sigio); 1411 break; 1412 1413 default: 1414 error = ENOTTY; 1415 break; 1416 } 1417 PIPE_UNLOCK(mpipe); 1418 out_unlocked: 1419 return (error); 1420 } 1421 1422 static int 1423 pipe_poll(fp, events, active_cred, td) 1424 struct file *fp; 1425 int events; 1426 struct ucred *active_cred; 1427 struct thread *td; 1428 { 1429 struct pipe *rpipe; 1430 struct pipe *wpipe; 1431 int levents, revents; 1432 #ifdef MAC 1433 int error; 1434 #endif 1435 1436 revents = 0; 1437 rpipe = fp->f_data; 1438 wpipe = PIPE_PEER(rpipe); 1439 PIPE_LOCK(rpipe); 1440 #ifdef MAC 1441 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair); 1442 if (error) 1443 goto locked_error; 1444 #endif 1445 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) 1446 if ((rpipe->pipe_state & PIPE_DIRECTW) || 1447 (rpipe->pipe_buffer.cnt > 0)) 1448 revents |= events & (POLLIN | POLLRDNORM); 1449 1450 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) 1451 if (wpipe->pipe_present != PIPE_ACTIVE || 1452 (wpipe->pipe_state & PIPE_EOF) || 1453 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) && 1454 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF || 1455 wpipe->pipe_buffer.size == 0))) 1456 revents |= events & (POLLOUT | POLLWRNORM); 1457 1458 levents = events & 1459 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND); 1460 if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents && 1461 fp->f_seqcount == rpipe->pipe_wgen) 1462 events |= POLLINIGNEOF; 1463 1464 if ((events & POLLINIGNEOF) == 0) { 1465 if (rpipe->pipe_state & PIPE_EOF) { 1466 revents |= (events & (POLLIN | POLLRDNORM)); 1467 if (wpipe->pipe_present != PIPE_ACTIVE || 1468 (wpipe->pipe_state & PIPE_EOF)) 1469 revents |= POLLHUP; 1470 } 1471 } 1472 1473 if (revents == 0) { 1474 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) { 1475 selrecord(td, &rpipe->pipe_sel); 1476 if (SEL_WAITING(&rpipe->pipe_sel)) 1477 rpipe->pipe_state |= PIPE_SEL; 1478 } 1479 1480 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) { 1481 selrecord(td, &wpipe->pipe_sel); 1482 if (SEL_WAITING(&wpipe->pipe_sel)) 1483 wpipe->pipe_state |= PIPE_SEL; 1484 } 1485 } 1486 #ifdef MAC 1487 locked_error: 1488 #endif 1489 PIPE_UNLOCK(rpipe); 1490 1491 return (revents); 1492 } 1493 1494 /* 1495 * We shouldn't need locks here as we're doing a read and this should 1496 * be a natural race. 1497 */ 1498 static int 1499 pipe_stat(fp, ub, active_cred, td) 1500 struct file *fp; 1501 struct stat *ub; 1502 struct ucred *active_cred; 1503 struct thread *td; 1504 { 1505 struct pipe *pipe; 1506 int new_unr; 1507 #ifdef MAC 1508 int error; 1509 #endif 1510 1511 pipe = fp->f_data; 1512 PIPE_LOCK(pipe); 1513 #ifdef MAC 1514 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair); 1515 if (error) { 1516 PIPE_UNLOCK(pipe); 1517 return (error); 1518 } 1519 #endif 1520 1521 /* For named pipes ask the underlying filesystem. */ 1522 if (pipe->pipe_state & PIPE_NAMED) { 1523 PIPE_UNLOCK(pipe); 1524 return (vnops.fo_stat(fp, ub, active_cred, td)); 1525 } 1526 1527 /* 1528 * Lazily allocate an inode number for the pipe. Most pipe 1529 * users do not call fstat(2) on the pipe, which means that 1530 * postponing the inode allocation until it is must be 1531 * returned to userland is useful. If alloc_unr failed, 1532 * assign st_ino zero instead of returning an error. 1533 * Special pipe_ino values: 1534 * -1 - not yet initialized; 1535 * 0 - alloc_unr failed, return 0 as st_ino forever. 1536 */ 1537 if (pipe->pipe_ino == (ino_t)-1) { 1538 new_unr = alloc_unr(pipeino_unr); 1539 if (new_unr != -1) 1540 pipe->pipe_ino = new_unr; 1541 else 1542 pipe->pipe_ino = 0; 1543 } 1544 PIPE_UNLOCK(pipe); 1545 1546 bzero(ub, sizeof(*ub)); 1547 ub->st_mode = S_IFIFO; 1548 ub->st_blksize = PAGE_SIZE; 1549 if (pipe->pipe_state & PIPE_DIRECTW) 1550 ub->st_size = pipe->pipe_map.cnt; 1551 else 1552 ub->st_size = pipe->pipe_buffer.cnt; 1553 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize; 1554 ub->st_atim = pipe->pipe_atime; 1555 ub->st_mtim = pipe->pipe_mtime; 1556 ub->st_ctim = pipe->pipe_ctime; 1557 ub->st_uid = fp->f_cred->cr_uid; 1558 ub->st_gid = fp->f_cred->cr_gid; 1559 ub->st_dev = pipedev_ino; 1560 ub->st_ino = pipe->pipe_ino; 1561 /* 1562 * Left as 0: st_nlink, st_rdev, st_flags, st_gen. 1563 */ 1564 return (0); 1565 } 1566 1567 /* ARGSUSED */ 1568 static int 1569 pipe_close(fp, td) 1570 struct file *fp; 1571 struct thread *td; 1572 { 1573 1574 if (fp->f_vnode != NULL) 1575 return vnops.fo_close(fp, td); 1576 fp->f_ops = &badfileops; 1577 pipe_dtor(fp->f_data); 1578 fp->f_data = NULL; 1579 return (0); 1580 } 1581 1582 static int 1583 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td) 1584 { 1585 struct pipe *cpipe; 1586 int error; 1587 1588 cpipe = fp->f_data; 1589 if (cpipe->pipe_state & PIPE_NAMED) 1590 error = vn_chmod(fp, mode, active_cred, td); 1591 else 1592 error = invfo_chmod(fp, mode, active_cred, td); 1593 return (error); 1594 } 1595 1596 static int 1597 pipe_chown(fp, uid, gid, active_cred, td) 1598 struct file *fp; 1599 uid_t uid; 1600 gid_t gid; 1601 struct ucred *active_cred; 1602 struct thread *td; 1603 { 1604 struct pipe *cpipe; 1605 int error; 1606 1607 cpipe = fp->f_data; 1608 if (cpipe->pipe_state & PIPE_NAMED) 1609 error = vn_chown(fp, uid, gid, active_cred, td); 1610 else 1611 error = invfo_chown(fp, uid, gid, active_cred, td); 1612 return (error); 1613 } 1614 1615 static void 1616 pipe_free_kmem(cpipe) 1617 struct pipe *cpipe; 1618 { 1619 1620 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), 1621 ("pipe_free_kmem: pipe mutex locked")); 1622 1623 if (cpipe->pipe_buffer.buffer != NULL) { 1624 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size); 1625 vm_map_remove(pipe_map, 1626 (vm_offset_t)cpipe->pipe_buffer.buffer, 1627 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size); 1628 cpipe->pipe_buffer.buffer = NULL; 1629 } 1630 #ifndef PIPE_NODIRECT 1631 { 1632 cpipe->pipe_map.cnt = 0; 1633 cpipe->pipe_map.pos = 0; 1634 cpipe->pipe_map.npages = 0; 1635 } 1636 #endif 1637 } 1638 1639 /* 1640 * shutdown the pipe 1641 */ 1642 static void 1643 pipeclose(cpipe) 1644 struct pipe *cpipe; 1645 { 1646 struct pipepair *pp; 1647 struct pipe *ppipe; 1648 1649 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL")); 1650 1651 PIPE_LOCK(cpipe); 1652 pipelock(cpipe, 0); 1653 pp = cpipe->pipe_pair; 1654 1655 pipeselwakeup(cpipe); 1656 1657 /* 1658 * If the other side is blocked, wake it up saying that 1659 * we want to close it down. 1660 */ 1661 cpipe->pipe_state |= PIPE_EOF; 1662 while (cpipe->pipe_busy) { 1663 wakeup(cpipe); 1664 cpipe->pipe_state |= PIPE_WANT; 1665 pipeunlock(cpipe); 1666 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0); 1667 pipelock(cpipe, 0); 1668 } 1669 1670 1671 /* 1672 * Disconnect from peer, if any. 1673 */ 1674 ppipe = cpipe->pipe_peer; 1675 if (ppipe->pipe_present == PIPE_ACTIVE) { 1676 pipeselwakeup(ppipe); 1677 1678 ppipe->pipe_state |= PIPE_EOF; 1679 wakeup(ppipe); 1680 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0); 1681 } 1682 1683 /* 1684 * Mark this endpoint as free. Release kmem resources. We 1685 * don't mark this endpoint as unused until we've finished 1686 * doing that, or the pipe might disappear out from under 1687 * us. 1688 */ 1689 PIPE_UNLOCK(cpipe); 1690 pipe_free_kmem(cpipe); 1691 PIPE_LOCK(cpipe); 1692 cpipe->pipe_present = PIPE_CLOSING; 1693 pipeunlock(cpipe); 1694 1695 /* 1696 * knlist_clear() may sleep dropping the PIPE_MTX. Set the 1697 * PIPE_FINALIZED, that allows other end to free the 1698 * pipe_pair, only after the knotes are completely dismantled. 1699 */ 1700 knlist_clear(&cpipe->pipe_sel.si_note, 1); 1701 cpipe->pipe_present = PIPE_FINALIZED; 1702 seldrain(&cpipe->pipe_sel); 1703 knlist_destroy(&cpipe->pipe_sel.si_note); 1704 1705 /* 1706 * If both endpoints are now closed, release the memory for the 1707 * pipe pair. If not, unlock. 1708 */ 1709 if (ppipe->pipe_present == PIPE_FINALIZED) { 1710 PIPE_UNLOCK(cpipe); 1711 #ifdef MAC 1712 mac_pipe_destroy(pp); 1713 #endif 1714 uma_zfree(pipe_zone, cpipe->pipe_pair); 1715 } else 1716 PIPE_UNLOCK(cpipe); 1717 } 1718 1719 /*ARGSUSED*/ 1720 static int 1721 pipe_kqfilter(struct file *fp, struct knote *kn) 1722 { 1723 struct pipe *cpipe; 1724 1725 /* 1726 * If a filter is requested that is not supported by this file 1727 * descriptor, don't return an error, but also don't ever generate an 1728 * event. 1729 */ 1730 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) { 1731 kn->kn_fop = &pipe_nfiltops; 1732 return (0); 1733 } 1734 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) { 1735 kn->kn_fop = &pipe_nfiltops; 1736 return (0); 1737 } 1738 cpipe = fp->f_data; 1739 PIPE_LOCK(cpipe); 1740 switch (kn->kn_filter) { 1741 case EVFILT_READ: 1742 kn->kn_fop = &pipe_rfiltops; 1743 break; 1744 case EVFILT_WRITE: 1745 kn->kn_fop = &pipe_wfiltops; 1746 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) { 1747 /* other end of pipe has been closed */ 1748 PIPE_UNLOCK(cpipe); 1749 return (EPIPE); 1750 } 1751 cpipe = PIPE_PEER(cpipe); 1752 break; 1753 default: 1754 PIPE_UNLOCK(cpipe); 1755 return (EINVAL); 1756 } 1757 1758 kn->kn_hook = cpipe; 1759 knlist_add(&cpipe->pipe_sel.si_note, kn, 1); 1760 PIPE_UNLOCK(cpipe); 1761 return (0); 1762 } 1763 1764 static void 1765 filt_pipedetach(struct knote *kn) 1766 { 1767 struct pipe *cpipe = kn->kn_hook; 1768 1769 PIPE_LOCK(cpipe); 1770 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1); 1771 PIPE_UNLOCK(cpipe); 1772 } 1773 1774 /*ARGSUSED*/ 1775 static int 1776 filt_piperead(struct knote *kn, long hint) 1777 { 1778 struct pipe *rpipe = kn->kn_hook; 1779 struct pipe *wpipe = rpipe->pipe_peer; 1780 int ret; 1781 1782 PIPE_LOCK(rpipe); 1783 kn->kn_data = rpipe->pipe_buffer.cnt; 1784 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) 1785 kn->kn_data = rpipe->pipe_map.cnt; 1786 1787 if ((rpipe->pipe_state & PIPE_EOF) || 1788 wpipe->pipe_present != PIPE_ACTIVE || 1789 (wpipe->pipe_state & PIPE_EOF)) { 1790 kn->kn_flags |= EV_EOF; 1791 PIPE_UNLOCK(rpipe); 1792 return (1); 1793 } 1794 ret = kn->kn_data > 0; 1795 PIPE_UNLOCK(rpipe); 1796 return ret; 1797 } 1798 1799 /*ARGSUSED*/ 1800 static int 1801 filt_pipewrite(struct knote *kn, long hint) 1802 { 1803 struct pipe *wpipe; 1804 1805 wpipe = kn->kn_hook; 1806 PIPE_LOCK(wpipe); 1807 if (wpipe->pipe_present != PIPE_ACTIVE || 1808 (wpipe->pipe_state & PIPE_EOF)) { 1809 kn->kn_data = 0; 1810 kn->kn_flags |= EV_EOF; 1811 PIPE_UNLOCK(wpipe); 1812 return (1); 1813 } 1814 kn->kn_data = (wpipe->pipe_buffer.size > 0) ? 1815 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF; 1816 if (wpipe->pipe_state & PIPE_DIRECTW) 1817 kn->kn_data = 0; 1818 1819 PIPE_UNLOCK(wpipe); 1820 return (kn->kn_data >= PIPE_BUF); 1821 } 1822 1823 static void 1824 filt_pipedetach_notsup(struct knote *kn) 1825 { 1826 1827 } 1828 1829 static int 1830 filt_pipenotsup(struct knote *kn, long hint) 1831 { 1832 1833 return (0); 1834 }
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