1 /*- 2 * Copyright (c) 1996 John S. Dyson 3 * Copyright (c) 2012 Giovanni Trematerra 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice immediately at the beginning of the file, without modification, 11 * this list of conditions, and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Absolutely no warranty of function or purpose is made by the author 16 * John S. Dyson. 17 * 4. Modifications may be freely made to this file if the above conditions 18 * are met. 19 */ 20 21 /* 22 * This file contains a high-performance replacement for the socket-based 23 * pipes scheme originally used in FreeBSD/4.4Lite. It does not support 24 * all features of sockets, but does do everything that pipes normally 25 * do. 26 */ 27 28 /* 29 * This code has two modes of operation, a small write mode and a large 30 * write mode. The small write mode acts like conventional pipes with 31 * a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the 32 * "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT 33 * and PIPE_SIZE in size, the sending process pins the underlying pages in 34 * memory, and the receiving process copies directly from these pinned pages 35 * in the sending process. 36 * 37 * If the sending process receives a signal, it is possible that it will 38 * go away, and certainly its address space can change, because control 39 * is returned back to the user-mode side. In that case, the pipe code 40 * arranges to copy the buffer supplied by the user process, to a pageable 41 * kernel buffer, and the receiving process will grab the data from the 42 * pageable kernel buffer. Since signals don't happen all that often, 43 * the copy operation is normally eliminated. 44 * 45 * The constant PIPE_MINDIRECT is chosen to make sure that buffering will 46 * happen for small transfers so that the system will not spend all of 47 * its time context switching. 48 * 49 * In order to limit the resource use of pipes, two sysctls exist: 50 * 51 * kern.ipc.maxpipekva - This is a hard limit on the amount of pageable 52 * address space available to us in pipe_map. This value is normally 53 * autotuned, but may also be loader tuned. 54 * 55 * kern.ipc.pipekva - This read-only sysctl tracks the current amount of 56 * memory in use by pipes. 57 * 58 * Based on how large pipekva is relative to maxpipekva, the following 59 * will happen: 60 * 61 * 0% - 50%: 62 * New pipes are given 16K of memory backing, pipes may dynamically 63 * grow to as large as 64K where needed. 64 * 50% - 75%: 65 * New pipes are given 4K (or PAGE_SIZE) of memory backing, 66 * existing pipes may NOT grow. 67 * 75% - 100%: 68 * New pipes are given 4K (or PAGE_SIZE) of memory backing, 69 * existing pipes will be shrunk down to 4K whenever possible. 70 * 71 * Resizing may be disabled by setting kern.ipc.piperesizeallowed=0. If 72 * that is set, the only resize that will occur is the 0 -> SMALL_PIPE_SIZE 73 * resize which MUST occur for reverse-direction pipes when they are 74 * first used. 75 * 76 * Additional information about the current state of pipes may be obtained 77 * from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail, 78 * and kern.ipc.piperesizefail. 79 * 80 * Locking rules: There are two locks present here: A mutex, used via 81 * PIPE_LOCK, and a flag, used via pipelock(). All locking is done via 82 * the flag, as mutexes can not persist over uiomove. The mutex 83 * exists only to guard access to the flag, and is not in itself a 84 * locking mechanism. Also note that there is only a single mutex for 85 * both directions of a pipe. 86 * 87 * As pipelock() may have to sleep before it can acquire the flag, it 88 * is important to reread all data after a call to pipelock(); everything 89 * in the structure may have changed. 90 */ 91 92 #include <sys/cdefs.h> 93 __FBSDID("$FreeBSD$"); 94 95 #include <sys/param.h> 96 #include <sys/systm.h> 97 #include <sys/conf.h> 98 #include <sys/fcntl.h> 99 #include <sys/file.h> 100 #include <sys/filedesc.h> 101 #include <sys/filio.h> 102 #include <sys/kernel.h> 103 #include <sys/lock.h> 104 #include <sys/mutex.h> 105 #include <sys/ttycom.h> 106 #include <sys/stat.h> 107 #include <sys/malloc.h> 108 #include <sys/poll.h> 109 #include <sys/selinfo.h> 110 #include <sys/signalvar.h> 111 #include <sys/syscallsubr.h> 112 #include <sys/sysctl.h> 113 #include <sys/sysproto.h> 114 #include <sys/pipe.h> 115 #include <sys/proc.h> 116 #include <sys/vnode.h> 117 #include <sys/uio.h> 118 #include <sys/user.h> 119 #include <sys/event.h> 120 121 #include <security/mac/mac_framework.h> 122 123 #include <vm/vm.h> 124 #include <vm/vm_param.h> 125 #include <vm/vm_object.h> 126 #include <vm/vm_kern.h> 127 #include <vm/vm_extern.h> 128 #include <vm/pmap.h> 129 #include <vm/vm_map.h> 130 #include <vm/vm_page.h> 131 #include <vm/uma.h> 132 133 /* 134 * Use this define if you want to disable *fancy* VM things. Expect an 135 * approx 30% decrease in transfer rate. This could be useful for 136 * NetBSD or OpenBSD. 137 */ 138 /* #define PIPE_NODIRECT */ 139 140 #define PIPE_PEER(pipe) \ 141 (((pipe)->pipe_state & PIPE_NAMED) ? (pipe) : ((pipe)->pipe_peer)) 142 143 /* 144 * interfaces to the outside world 145 */ 146 static fo_rdwr_t pipe_read; 147 static fo_rdwr_t pipe_write; 148 static fo_truncate_t pipe_truncate; 149 static fo_ioctl_t pipe_ioctl; 150 static fo_poll_t pipe_poll; 151 static fo_kqfilter_t pipe_kqfilter; 152 static fo_stat_t pipe_stat; 153 static fo_close_t pipe_close; 154 static fo_chmod_t pipe_chmod; 155 static fo_chown_t pipe_chown; 156 static fo_fill_kinfo_t pipe_fill_kinfo; 157 158 struct fileops pipeops = { 159 .fo_read = pipe_read, 160 .fo_write = pipe_write, 161 .fo_truncate = pipe_truncate, 162 .fo_ioctl = pipe_ioctl, 163 .fo_poll = pipe_poll, 164 .fo_kqfilter = pipe_kqfilter, 165 .fo_stat = pipe_stat, 166 .fo_close = pipe_close, 167 .fo_chmod = pipe_chmod, 168 .fo_chown = pipe_chown, 169 .fo_sendfile = invfo_sendfile, 170 .fo_fill_kinfo = pipe_fill_kinfo, 171 .fo_flags = DFLAG_PASSABLE 172 }; 173 174 static void filt_pipedetach(struct knote *kn); 175 static void filt_pipedetach_notsup(struct knote *kn); 176 static int filt_pipenotsup(struct knote *kn, long hint); 177 static int filt_piperead(struct knote *kn, long hint); 178 static int filt_pipewrite(struct knote *kn, long hint); 179 180 static struct filterops pipe_nfiltops = { 181 .f_isfd = 1, 182 .f_detach = filt_pipedetach_notsup, 183 .f_event = filt_pipenotsup 184 }; 185 static struct filterops pipe_rfiltops = { 186 .f_isfd = 1, 187 .f_detach = filt_pipedetach, 188 .f_event = filt_piperead 189 }; 190 static struct filterops pipe_wfiltops = { 191 .f_isfd = 1, 192 .f_detach = filt_pipedetach, 193 .f_event = filt_pipewrite 194 }; 195 196 /* 197 * Default pipe buffer size(s), this can be kind-of large now because pipe 198 * space is pageable. The pipe code will try to maintain locality of 199 * reference for performance reasons, so small amounts of outstanding I/O 200 * will not wipe the cache. 201 */ 202 #define MINPIPESIZE (PIPE_SIZE/3) 203 #define MAXPIPESIZE (2*PIPE_SIZE/3) 204 205 static long amountpipekva; 206 static int pipefragretry; 207 static int pipeallocfail; 208 static int piperesizefail; 209 static int piperesizeallowed = 1; 210 211 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, 212 &maxpipekva, 0, "Pipe KVA limit"); 213 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD, 214 &amountpipekva, 0, "Pipe KVA usage"); 215 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD, 216 &pipefragretry, 0, "Pipe allocation retries due to fragmentation"); 217 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD, 218 &pipeallocfail, 0, "Pipe allocation failures"); 219 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD, 220 &piperesizefail, 0, "Pipe resize failures"); 221 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW, 222 &piperesizeallowed, 0, "Pipe resizing allowed"); 223 224 static void pipeinit(void *dummy __unused); 225 static void pipeclose(struct pipe *cpipe); 226 static void pipe_free_kmem(struct pipe *cpipe); 227 static void pipe_create(struct pipe *pipe, int backing); 228 static void pipe_paircreate(struct thread *td, struct pipepair **p_pp); 229 static __inline int pipelock(struct pipe *cpipe, int catch); 230 static __inline void pipeunlock(struct pipe *cpipe); 231 #ifndef PIPE_NODIRECT 232 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio); 233 static void pipe_destroy_write_buffer(struct pipe *wpipe); 234 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio); 235 static void pipe_clone_write_buffer(struct pipe *wpipe); 236 #endif 237 static int pipespace(struct pipe *cpipe, int size); 238 static int pipespace_new(struct pipe *cpipe, int size); 239 240 static int pipe_zone_ctor(void *mem, int size, void *arg, int flags); 241 static int pipe_zone_init(void *mem, int size, int flags); 242 static void pipe_zone_fini(void *mem, int size); 243 244 static uma_zone_t pipe_zone; 245 static struct unrhdr *pipeino_unr; 246 static dev_t pipedev_ino; 247 248 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL); 249 250 static void 251 pipeinit(void *dummy __unused) 252 { 253 254 pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair), 255 pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini, 256 UMA_ALIGN_PTR, 0); 257 KASSERT(pipe_zone != NULL, ("pipe_zone not initialized")); 258 pipeino_unr = new_unrhdr(1, INT32_MAX, NULL); 259 KASSERT(pipeino_unr != NULL, ("pipe fake inodes not initialized")); 260 pipedev_ino = devfs_alloc_cdp_inode(); 261 KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized")); 262 } 263 264 static int 265 pipe_zone_ctor(void *mem, int size, void *arg, int flags) 266 { 267 struct pipepair *pp; 268 struct pipe *rpipe, *wpipe; 269 270 KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size")); 271 272 pp = (struct pipepair *)mem; 273 274 /* 275 * We zero both pipe endpoints to make sure all the kmem pointers 276 * are NULL, flag fields are zero'd, etc. We timestamp both 277 * endpoints with the same time. 278 */ 279 rpipe = &pp->pp_rpipe; 280 bzero(rpipe, sizeof(*rpipe)); 281 vfs_timestamp(&rpipe->pipe_ctime); 282 rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime; 283 284 wpipe = &pp->pp_wpipe; 285 bzero(wpipe, sizeof(*wpipe)); 286 wpipe->pipe_ctime = rpipe->pipe_ctime; 287 wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime; 288 289 rpipe->pipe_peer = wpipe; 290 rpipe->pipe_pair = pp; 291 wpipe->pipe_peer = rpipe; 292 wpipe->pipe_pair = pp; 293 294 /* 295 * Mark both endpoints as present; they will later get free'd 296 * one at a time. When both are free'd, then the whole pair 297 * is released. 298 */ 299 rpipe->pipe_present = PIPE_ACTIVE; 300 wpipe->pipe_present = PIPE_ACTIVE; 301 302 /* 303 * Eventually, the MAC Framework may initialize the label 304 * in ctor or init, but for now we do it elswhere to avoid 305 * blocking in ctor or init. 306 */ 307 pp->pp_label = NULL; 308 309 return (0); 310 } 311 312 static int 313 pipe_zone_init(void *mem, int size, int flags) 314 { 315 struct pipepair *pp; 316 317 KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size")); 318 319 pp = (struct pipepair *)mem; 320 321 mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_RECURSE); 322 return (0); 323 } 324 325 static void 326 pipe_zone_fini(void *mem, int size) 327 { 328 struct pipepair *pp; 329 330 KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size")); 331 332 pp = (struct pipepair *)mem; 333 334 mtx_destroy(&pp->pp_mtx); 335 } 336 337 static void 338 pipe_paircreate(struct thread *td, struct pipepair **p_pp) 339 { 340 struct pipepair *pp; 341 struct pipe *rpipe, *wpipe; 342 343 *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK); 344 #ifdef MAC 345 /* 346 * The MAC label is shared between the connected endpoints. As a 347 * result mac_pipe_init() and mac_pipe_create() are called once 348 * for the pair, and not on the endpoints. 349 */ 350 mac_pipe_init(pp); 351 mac_pipe_create(td->td_ucred, pp); 352 #endif 353 rpipe = &pp->pp_rpipe; 354 wpipe = &pp->pp_wpipe; 355 356 knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe)); 357 knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe)); 358 359 /* Only the forward direction pipe is backed by default */ 360 pipe_create(rpipe, 1); 361 pipe_create(wpipe, 0); 362 363 rpipe->pipe_state |= PIPE_DIRECTOK; 364 wpipe->pipe_state |= PIPE_DIRECTOK; 365 } 366 367 void 368 pipe_named_ctor(struct pipe **ppipe, struct thread *td) 369 { 370 struct pipepair *pp; 371 372 pipe_paircreate(td, &pp); 373 pp->pp_rpipe.pipe_state |= PIPE_NAMED; 374 *ppipe = &pp->pp_rpipe; 375 } 376 377 void 378 pipe_dtor(struct pipe *dpipe) 379 { 380 ino_t ino; 381 382 ino = dpipe->pipe_ino; 383 funsetown(&dpipe->pipe_sigio); 384 pipeclose(dpipe); 385 if (dpipe->pipe_state & PIPE_NAMED) { 386 dpipe = dpipe->pipe_peer; 387 funsetown(&dpipe->pipe_sigio); 388 pipeclose(dpipe); 389 } 390 if (ino != 0 && ino != (ino_t)-1) 391 free_unr(pipeino_unr, ino); 392 } 393 394 /* 395 * The pipe system call for the DTYPE_PIPE type of pipes. If we fail, let 396 * the zone pick up the pieces via pipeclose(). 397 */ 398 int 399 kern_pipe(struct thread *td, int fildes[2]) 400 { 401 402 return (kern_pipe2(td, fildes, 0)); 403 } 404 405 int 406 kern_pipe2(struct thread *td, int fildes[2], int flags) 407 { 408 struct filedesc *fdp; 409 struct file *rf, *wf; 410 struct pipe *rpipe, *wpipe; 411 struct pipepair *pp; 412 int fd, fflags, error; 413 414 fdp = td->td_proc->p_fd; 415 pipe_paircreate(td, &pp); 416 rpipe = &pp->pp_rpipe; 417 wpipe = &pp->pp_wpipe; 418 error = falloc(td, &rf, &fd, flags); 419 if (error) { 420 pipeclose(rpipe); 421 pipeclose(wpipe); 422 return (error); 423 } 424 /* An extra reference on `rf' has been held for us by falloc(). */ 425 fildes[0] = fd; 426 427 fflags = FREAD | FWRITE; 428 if ((flags & O_NONBLOCK) != 0) 429 fflags |= FNONBLOCK; 430 431 /* 432 * Warning: once we've gotten past allocation of the fd for the 433 * read-side, we can only drop the read side via fdrop() in order 434 * to avoid races against processes which manage to dup() the read 435 * side while we are blocked trying to allocate the write side. 436 */ 437 finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops); 438 error = falloc(td, &wf, &fd, flags); 439 if (error) { 440 fdclose(fdp, rf, fildes[0], td); 441 fdrop(rf, td); 442 /* rpipe has been closed by fdrop(). */ 443 pipeclose(wpipe); 444 return (error); 445 } 446 /* An extra reference on `wf' has been held for us by falloc(). */ 447 finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops); 448 fdrop(wf, td); 449 fildes[1] = fd; 450 fdrop(rf, td); 451 452 return (0); 453 } 454 455 /* ARGSUSED */ 456 int 457 sys_pipe(struct thread *td, struct pipe_args *uap) 458 { 459 int error; 460 int fildes[2]; 461 462 error = kern_pipe(td, fildes); 463 if (error) 464 return (error); 465 466 td->td_retval[0] = fildes[0]; 467 td->td_retval[1] = fildes[1]; 468 469 return (0); 470 } 471 472 int 473 sys_pipe2(struct thread *td, struct pipe2_args *uap) 474 { 475 int error, fildes[2]; 476 477 if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK)) 478 return (EINVAL); 479 error = kern_pipe2(td, fildes, uap->flags); 480 if (error) 481 return (error); 482 error = copyout(fildes, uap->fildes, 2 * sizeof(int)); 483 if (error) { 484 (void)kern_close(td, fildes[0]); 485 (void)kern_close(td, fildes[1]); 486 } 487 return (error); 488 } 489 490 /* 491 * Allocate kva for pipe circular buffer, the space is pageable 492 * This routine will 'realloc' the size of a pipe safely, if it fails 493 * it will retain the old buffer. 494 * If it fails it will return ENOMEM. 495 */ 496 static int 497 pipespace_new(cpipe, size) 498 struct pipe *cpipe; 499 int size; 500 { 501 caddr_t buffer; 502 int error, cnt, firstseg; 503 static int curfail = 0; 504 static struct timeval lastfail; 505 506 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked")); 507 KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW), 508 ("pipespace: resize of direct writes not allowed")); 509 retry: 510 cnt = cpipe->pipe_buffer.cnt; 511 if (cnt > size) 512 size = cnt; 513 514 size = round_page(size); 515 buffer = (caddr_t) vm_map_min(pipe_map); 516 517 error = vm_map_find(pipe_map, NULL, 0, 518 (vm_offset_t *) &buffer, size, 0, VMFS_ANY_SPACE, 519 VM_PROT_ALL, VM_PROT_ALL, 0); 520 if (error != KERN_SUCCESS) { 521 if ((cpipe->pipe_buffer.buffer == NULL) && 522 (size > SMALL_PIPE_SIZE)) { 523 size = SMALL_PIPE_SIZE; 524 pipefragretry++; 525 goto retry; 526 } 527 if (cpipe->pipe_buffer.buffer == NULL) { 528 pipeallocfail++; 529 if (ppsratecheck(&lastfail, &curfail, 1)) 530 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n"); 531 } else { 532 piperesizefail++; 533 } 534 return (ENOMEM); 535 } 536 537 /* copy data, then free old resources if we're resizing */ 538 if (cnt > 0) { 539 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) { 540 firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out; 541 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 542 buffer, firstseg); 543 if ((cnt - firstseg) > 0) 544 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg], 545 cpipe->pipe_buffer.in); 546 } else { 547 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out], 548 buffer, cnt); 549 } 550 } 551 pipe_free_kmem(cpipe); 552 cpipe->pipe_buffer.buffer = buffer; 553 cpipe->pipe_buffer.size = size; 554 cpipe->pipe_buffer.in = cnt; 555 cpipe->pipe_buffer.out = 0; 556 cpipe->pipe_buffer.cnt = cnt; 557 atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size); 558 return (0); 559 } 560 561 /* 562 * Wrapper for pipespace_new() that performs locking assertions. 563 */ 564 static int 565 pipespace(cpipe, size) 566 struct pipe *cpipe; 567 int size; 568 { 569 570 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 571 ("Unlocked pipe passed to pipespace")); 572 return (pipespace_new(cpipe, size)); 573 } 574 575 /* 576 * lock a pipe for I/O, blocking other access 577 */ 578 static __inline int 579 pipelock(cpipe, catch) 580 struct pipe *cpipe; 581 int catch; 582 { 583 int error; 584 585 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 586 while (cpipe->pipe_state & PIPE_LOCKFL) { 587 cpipe->pipe_state |= PIPE_LWANT; 588 error = msleep(cpipe, PIPE_MTX(cpipe), 589 catch ? (PRIBIO | PCATCH) : PRIBIO, 590 "pipelk", 0); 591 if (error != 0) 592 return (error); 593 } 594 cpipe->pipe_state |= PIPE_LOCKFL; 595 return (0); 596 } 597 598 /* 599 * unlock a pipe I/O lock 600 */ 601 static __inline void 602 pipeunlock(cpipe) 603 struct pipe *cpipe; 604 { 605 606 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 607 KASSERT(cpipe->pipe_state & PIPE_LOCKFL, 608 ("Unlocked pipe passed to pipeunlock")); 609 cpipe->pipe_state &= ~PIPE_LOCKFL; 610 if (cpipe->pipe_state & PIPE_LWANT) { 611 cpipe->pipe_state &= ~PIPE_LWANT; 612 wakeup(cpipe); 613 } 614 } 615 616 void 617 pipeselwakeup(cpipe) 618 struct pipe *cpipe; 619 { 620 621 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 622 if (cpipe->pipe_state & PIPE_SEL) { 623 selwakeuppri(&cpipe->pipe_sel, PSOCK); 624 if (!SEL_WAITING(&cpipe->pipe_sel)) 625 cpipe->pipe_state &= ~PIPE_SEL; 626 } 627 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) 628 pgsigio(&cpipe->pipe_sigio, SIGIO, 0); 629 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0); 630 } 631 632 /* 633 * Initialize and allocate VM and memory for pipe. The structure 634 * will start out zero'd from the ctor, so we just manage the kmem. 635 */ 636 static void 637 pipe_create(pipe, backing) 638 struct pipe *pipe; 639 int backing; 640 { 641 642 if (backing) { 643 /* 644 * Note that these functions can fail if pipe map is exhausted 645 * (as a result of too many pipes created), but we ignore the 646 * error as it is not fatal and could be provoked by 647 * unprivileged users. The only consequence is worse performance 648 * with given pipe. 649 */ 650 if (amountpipekva > maxpipekva / 2) 651 (void)pipespace_new(pipe, SMALL_PIPE_SIZE); 652 else 653 (void)pipespace_new(pipe, PIPE_SIZE); 654 } 655 656 pipe->pipe_ino = -1; 657 } 658 659 /* ARGSUSED */ 660 static int 661 pipe_read(fp, uio, active_cred, flags, td) 662 struct file *fp; 663 struct uio *uio; 664 struct ucred *active_cred; 665 struct thread *td; 666 int flags; 667 { 668 struct pipe *rpipe; 669 int error; 670 int nread = 0; 671 int size; 672 673 rpipe = fp->f_data; 674 PIPE_LOCK(rpipe); 675 ++rpipe->pipe_busy; 676 error = pipelock(rpipe, 1); 677 if (error) 678 goto unlocked_error; 679 680 #ifdef MAC 681 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair); 682 if (error) 683 goto locked_error; 684 #endif 685 if (amountpipekva > (3 * maxpipekva) / 4) { 686 if (!(rpipe->pipe_state & PIPE_DIRECTW) && 687 (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) && 688 (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) && 689 (piperesizeallowed == 1)) { 690 PIPE_UNLOCK(rpipe); 691 pipespace(rpipe, SMALL_PIPE_SIZE); 692 PIPE_LOCK(rpipe); 693 } 694 } 695 696 while (uio->uio_resid) { 697 /* 698 * normal pipe buffer receive 699 */ 700 if (rpipe->pipe_buffer.cnt > 0) { 701 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 702 if (size > rpipe->pipe_buffer.cnt) 703 size = rpipe->pipe_buffer.cnt; 704 if (size > uio->uio_resid) 705 size = uio->uio_resid; 706 707 PIPE_UNLOCK(rpipe); 708 error = uiomove( 709 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 710 size, uio); 711 PIPE_LOCK(rpipe); 712 if (error) 713 break; 714 715 rpipe->pipe_buffer.out += size; 716 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 717 rpipe->pipe_buffer.out = 0; 718 719 rpipe->pipe_buffer.cnt -= size; 720 721 /* 722 * If there is no more to read in the pipe, reset 723 * its pointers to the beginning. This improves 724 * cache hit stats. 725 */ 726 if (rpipe->pipe_buffer.cnt == 0) { 727 rpipe->pipe_buffer.in = 0; 728 rpipe->pipe_buffer.out = 0; 729 } 730 nread += size; 731 #ifndef PIPE_NODIRECT 732 /* 733 * Direct copy, bypassing a kernel buffer. 734 */ 735 } else if ((size = rpipe->pipe_map.cnt) && 736 (rpipe->pipe_state & PIPE_DIRECTW)) { 737 if (size > uio->uio_resid) 738 size = (u_int) uio->uio_resid; 739 740 PIPE_UNLOCK(rpipe); 741 error = uiomove_fromphys(rpipe->pipe_map.ms, 742 rpipe->pipe_map.pos, size, uio); 743 PIPE_LOCK(rpipe); 744 if (error) 745 break; 746 nread += size; 747 rpipe->pipe_map.pos += size; 748 rpipe->pipe_map.cnt -= size; 749 if (rpipe->pipe_map.cnt == 0) { 750 rpipe->pipe_state &= ~(PIPE_DIRECTW|PIPE_WANTW); 751 wakeup(rpipe); 752 } 753 #endif 754 } else { 755 /* 756 * detect EOF condition 757 * read returns 0 on EOF, no need to set error 758 */ 759 if (rpipe->pipe_state & PIPE_EOF) 760 break; 761 762 /* 763 * If the "write-side" has been blocked, wake it up now. 764 */ 765 if (rpipe->pipe_state & PIPE_WANTW) { 766 rpipe->pipe_state &= ~PIPE_WANTW; 767 wakeup(rpipe); 768 } 769 770 /* 771 * Break if some data was read. 772 */ 773 if (nread > 0) 774 break; 775 776 /* 777 * Unlock the pipe buffer for our remaining processing. 778 * We will either break out with an error or we will 779 * sleep and relock to loop. 780 */ 781 pipeunlock(rpipe); 782 783 /* 784 * Handle non-blocking mode operation or 785 * wait for more data. 786 */ 787 if (fp->f_flag & FNONBLOCK) { 788 error = EAGAIN; 789 } else { 790 rpipe->pipe_state |= PIPE_WANTR; 791 if ((error = msleep(rpipe, PIPE_MTX(rpipe), 792 PRIBIO | PCATCH, 793 "piperd", 0)) == 0) 794 error = pipelock(rpipe, 1); 795 } 796 if (error) 797 goto unlocked_error; 798 } 799 } 800 #ifdef MAC 801 locked_error: 802 #endif 803 pipeunlock(rpipe); 804 805 /* XXX: should probably do this before getting any locks. */ 806 if (error == 0) 807 vfs_timestamp(&rpipe->pipe_atime); 808 unlocked_error: 809 --rpipe->pipe_busy; 810 811 /* 812 * PIPE_WANT processing only makes sense if pipe_busy is 0. 813 */ 814 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 815 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 816 wakeup(rpipe); 817 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 818 /* 819 * Handle write blocking hysteresis. 820 */ 821 if (rpipe->pipe_state & PIPE_WANTW) { 822 rpipe->pipe_state &= ~PIPE_WANTW; 823 wakeup(rpipe); 824 } 825 } 826 827 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF) 828 pipeselwakeup(rpipe); 829 830 PIPE_UNLOCK(rpipe); 831 return (error); 832 } 833 834 #ifndef PIPE_NODIRECT 835 /* 836 * Map the sending processes' buffer into kernel space and wire it. 837 * This is similar to a physical write operation. 838 */ 839 static int 840 pipe_build_write_buffer(wpipe, uio) 841 struct pipe *wpipe; 842 struct uio *uio; 843 { 844 u_int size; 845 int i; 846 847 PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED); 848 KASSERT(wpipe->pipe_state & PIPE_DIRECTW, 849 ("Clone attempt on non-direct write pipe!")); 850 851 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size) 852 size = wpipe->pipe_buffer.size; 853 else 854 size = uio->uio_iov->iov_len; 855 856 if ((i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 857 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ, 858 wpipe->pipe_map.ms, PIPENPAGES)) < 0) 859 return (EFAULT); 860 861 /* 862 * set up the control block 863 */ 864 wpipe->pipe_map.npages = i; 865 wpipe->pipe_map.pos = 866 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 867 wpipe->pipe_map.cnt = size; 868 869 /* 870 * and update the uio data 871 */ 872 873 uio->uio_iov->iov_len -= size; 874 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size; 875 if (uio->uio_iov->iov_len == 0) 876 uio->uio_iov++; 877 uio->uio_resid -= size; 878 uio->uio_offset += size; 879 return (0); 880 } 881 882 /* 883 * unmap and unwire the process buffer 884 */ 885 static void 886 pipe_destroy_write_buffer(wpipe) 887 struct pipe *wpipe; 888 { 889 890 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 891 vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages); 892 wpipe->pipe_map.npages = 0; 893 } 894 895 /* 896 * In the case of a signal, the writing process might go away. This 897 * code copies the data into the circular buffer so that the source 898 * pages can be freed without loss of data. 899 */ 900 static void 901 pipe_clone_write_buffer(wpipe) 902 struct pipe *wpipe; 903 { 904 struct uio uio; 905 struct iovec iov; 906 int size; 907 int pos; 908 909 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 910 size = wpipe->pipe_map.cnt; 911 pos = wpipe->pipe_map.pos; 912 913 wpipe->pipe_buffer.in = size; 914 wpipe->pipe_buffer.out = 0; 915 wpipe->pipe_buffer.cnt = size; 916 wpipe->pipe_state &= ~PIPE_DIRECTW; 917 918 PIPE_UNLOCK(wpipe); 919 iov.iov_base = wpipe->pipe_buffer.buffer; 920 iov.iov_len = size; 921 uio.uio_iov = &iov; 922 uio.uio_iovcnt = 1; 923 uio.uio_offset = 0; 924 uio.uio_resid = size; 925 uio.uio_segflg = UIO_SYSSPACE; 926 uio.uio_rw = UIO_READ; 927 uio.uio_td = curthread; 928 uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio); 929 PIPE_LOCK(wpipe); 930 pipe_destroy_write_buffer(wpipe); 931 } 932 933 /* 934 * This implements the pipe buffer write mechanism. Note that only 935 * a direct write OR a normal pipe write can be pending at any given time. 936 * If there are any characters in the pipe buffer, the direct write will 937 * be deferred until the receiving process grabs all of the bytes from 938 * the pipe buffer. Then the direct mapping write is set-up. 939 */ 940 static int 941 pipe_direct_write(wpipe, uio) 942 struct pipe *wpipe; 943 struct uio *uio; 944 { 945 int error; 946 947 retry: 948 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 949 error = pipelock(wpipe, 1); 950 if (wpipe->pipe_state & PIPE_EOF) 951 error = EPIPE; 952 if (error) { 953 pipeunlock(wpipe); 954 goto error1; 955 } 956 while (wpipe->pipe_state & PIPE_DIRECTW) { 957 if (wpipe->pipe_state & PIPE_WANTR) { 958 wpipe->pipe_state &= ~PIPE_WANTR; 959 wakeup(wpipe); 960 } 961 pipeselwakeup(wpipe); 962 wpipe->pipe_state |= PIPE_WANTW; 963 pipeunlock(wpipe); 964 error = msleep(wpipe, PIPE_MTX(wpipe), 965 PRIBIO | PCATCH, "pipdww", 0); 966 if (error) 967 goto error1; 968 else 969 goto retry; 970 } 971 wpipe->pipe_map.cnt = 0; /* transfer not ready yet */ 972 if (wpipe->pipe_buffer.cnt > 0) { 973 if (wpipe->pipe_state & PIPE_WANTR) { 974 wpipe->pipe_state &= ~PIPE_WANTR; 975 wakeup(wpipe); 976 } 977 pipeselwakeup(wpipe); 978 wpipe->pipe_state |= PIPE_WANTW; 979 pipeunlock(wpipe); 980 error = msleep(wpipe, PIPE_MTX(wpipe), 981 PRIBIO | PCATCH, "pipdwc", 0); 982 if (error) 983 goto error1; 984 else 985 goto retry; 986 } 987 988 wpipe->pipe_state |= PIPE_DIRECTW; 989 990 PIPE_UNLOCK(wpipe); 991 error = pipe_build_write_buffer(wpipe, uio); 992 PIPE_LOCK(wpipe); 993 if (error) { 994 wpipe->pipe_state &= ~PIPE_DIRECTW; 995 pipeunlock(wpipe); 996 goto error1; 997 } 998 999 error = 0; 1000 while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) { 1001 if (wpipe->pipe_state & PIPE_EOF) { 1002 pipe_destroy_write_buffer(wpipe); 1003 pipeselwakeup(wpipe); 1004 pipeunlock(wpipe); 1005 error = EPIPE; 1006 goto error1; 1007 } 1008 if (wpipe->pipe_state & PIPE_WANTR) { 1009 wpipe->pipe_state &= ~PIPE_WANTR; 1010 wakeup(wpipe); 1011 } 1012 pipeselwakeup(wpipe); 1013 wpipe->pipe_state |= PIPE_WANTW; 1014 pipeunlock(wpipe); 1015 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH, 1016 "pipdwt", 0); 1017 pipelock(wpipe, 0); 1018 } 1019 1020 if (wpipe->pipe_state & PIPE_EOF) 1021 error = EPIPE; 1022 if (wpipe->pipe_state & PIPE_DIRECTW) { 1023 /* 1024 * this bit of trickery substitutes a kernel buffer for 1025 * the process that might be going away. 1026 */ 1027 pipe_clone_write_buffer(wpipe); 1028 } else { 1029 pipe_destroy_write_buffer(wpipe); 1030 } 1031 pipeunlock(wpipe); 1032 return (error); 1033 1034 error1: 1035 wakeup(wpipe); 1036 return (error); 1037 } 1038 #endif 1039 1040 static int 1041 pipe_write(fp, uio, active_cred, flags, td) 1042 struct file *fp; 1043 struct uio *uio; 1044 struct ucred *active_cred; 1045 struct thread *td; 1046 int flags; 1047 { 1048 int error = 0; 1049 int desiredsize; 1050 ssize_t orig_resid; 1051 struct pipe *wpipe, *rpipe; 1052 1053 rpipe = fp->f_data; 1054 wpipe = PIPE_PEER(rpipe); 1055 PIPE_LOCK(rpipe); 1056 error = pipelock(wpipe, 1); 1057 if (error) { 1058 PIPE_UNLOCK(rpipe); 1059 return (error); 1060 } 1061 /* 1062 * detect loss of pipe read side, issue SIGPIPE if lost. 1063 */ 1064 if (wpipe->pipe_present != PIPE_ACTIVE || 1065 (wpipe->pipe_state & PIPE_EOF)) { 1066 pipeunlock(wpipe); 1067 PIPE_UNLOCK(rpipe); 1068 return (EPIPE); 1069 } 1070 #ifdef MAC 1071 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair); 1072 if (error) { 1073 pipeunlock(wpipe); 1074 PIPE_UNLOCK(rpipe); 1075 return (error); 1076 } 1077 #endif 1078 ++wpipe->pipe_busy; 1079 1080 /* Choose a larger size if it's advantageous */ 1081 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size); 1082 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) { 1083 if (piperesizeallowed != 1) 1084 break; 1085 if (amountpipekva > maxpipekva / 2) 1086 break; 1087 if (desiredsize == BIG_PIPE_SIZE) 1088 break; 1089 desiredsize = desiredsize * 2; 1090 } 1091 1092 /* Choose a smaller size if we're in a OOM situation */ 1093 if ((amountpipekva > (3 * maxpipekva) / 4) && 1094 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) && 1095 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) && 1096 (piperesizeallowed == 1)) 1097 desiredsize = SMALL_PIPE_SIZE; 1098 1099 /* Resize if the above determined that a new size was necessary */ 1100 if ((desiredsize != wpipe->pipe_buffer.size) && 1101 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) { 1102 PIPE_UNLOCK(wpipe); 1103 pipespace(wpipe, desiredsize); 1104 PIPE_LOCK(wpipe); 1105 } 1106 if (wpipe->pipe_buffer.size == 0) { 1107 /* 1108 * This can only happen for reverse direction use of pipes 1109 * in a complete OOM situation. 1110 */ 1111 error = ENOMEM; 1112 --wpipe->pipe_busy; 1113 pipeunlock(wpipe); 1114 PIPE_UNLOCK(wpipe); 1115 return (error); 1116 } 1117 1118 pipeunlock(wpipe); 1119 1120 orig_resid = uio->uio_resid; 1121 1122 while (uio->uio_resid) { 1123 int space; 1124 1125 pipelock(wpipe, 0); 1126 if (wpipe->pipe_state & PIPE_EOF) { 1127 pipeunlock(wpipe); 1128 error = EPIPE; 1129 break; 1130 } 1131 #ifndef PIPE_NODIRECT 1132 /* 1133 * If the transfer is large, we can gain performance if 1134 * we do process-to-process copies directly. 1135 * If the write is non-blocking, we don't use the 1136 * direct write mechanism. 1137 * 1138 * The direct write mechanism will detect the reader going 1139 * away on us. 1140 */ 1141 if (uio->uio_segflg == UIO_USERSPACE && 1142 uio->uio_iov->iov_len >= PIPE_MINDIRECT && 1143 wpipe->pipe_buffer.size >= PIPE_MINDIRECT && 1144 (fp->f_flag & FNONBLOCK) == 0) { 1145 pipeunlock(wpipe); 1146 error = pipe_direct_write(wpipe, uio); 1147 if (error) 1148 break; 1149 continue; 1150 } 1151 #endif 1152 1153 /* 1154 * Pipe buffered writes cannot be coincidental with 1155 * direct writes. We wait until the currently executing 1156 * direct write is completed before we start filling the 1157 * pipe buffer. We break out if a signal occurs or the 1158 * reader goes away. 1159 */ 1160 if (wpipe->pipe_state & PIPE_DIRECTW) { 1161 if (wpipe->pipe_state & PIPE_WANTR) { 1162 wpipe->pipe_state &= ~PIPE_WANTR; 1163 wakeup(wpipe); 1164 } 1165 pipeselwakeup(wpipe); 1166 wpipe->pipe_state |= PIPE_WANTW; 1167 pipeunlock(wpipe); 1168 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH, 1169 "pipbww", 0); 1170 if (error) 1171 break; 1172 else 1173 continue; 1174 } 1175 1176 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1177 1178 /* Writes of size <= PIPE_BUF must be atomic. */ 1179 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 1180 space = 0; 1181 1182 if (space > 0) { 1183 int size; /* Transfer size */ 1184 int segsize; /* first segment to transfer */ 1185 1186 /* 1187 * Transfer size is minimum of uio transfer 1188 * and free space in pipe buffer. 1189 */ 1190 if (space > uio->uio_resid) 1191 size = uio->uio_resid; 1192 else 1193 size = space; 1194 /* 1195 * First segment to transfer is minimum of 1196 * transfer size and contiguous space in 1197 * pipe buffer. If first segment to transfer 1198 * is less than the transfer size, we've got 1199 * a wraparound in the buffer. 1200 */ 1201 segsize = wpipe->pipe_buffer.size - 1202 wpipe->pipe_buffer.in; 1203 if (segsize > size) 1204 segsize = size; 1205 1206 /* Transfer first segment */ 1207 1208 PIPE_UNLOCK(rpipe); 1209 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 1210 segsize, uio); 1211 PIPE_LOCK(rpipe); 1212 1213 if (error == 0 && segsize < size) { 1214 KASSERT(wpipe->pipe_buffer.in + segsize == 1215 wpipe->pipe_buffer.size, 1216 ("Pipe buffer wraparound disappeared")); 1217 /* 1218 * Transfer remaining part now, to 1219 * support atomic writes. Wraparound 1220 * happened. 1221 */ 1222 1223 PIPE_UNLOCK(rpipe); 1224 error = uiomove( 1225 &wpipe->pipe_buffer.buffer[0], 1226 size - segsize, uio); 1227 PIPE_LOCK(rpipe); 1228 } 1229 if (error == 0) { 1230 wpipe->pipe_buffer.in += size; 1231 if (wpipe->pipe_buffer.in >= 1232 wpipe->pipe_buffer.size) { 1233 KASSERT(wpipe->pipe_buffer.in == 1234 size - segsize + 1235 wpipe->pipe_buffer.size, 1236 ("Expected wraparound bad")); 1237 wpipe->pipe_buffer.in = size - segsize; 1238 } 1239 1240 wpipe->pipe_buffer.cnt += size; 1241 KASSERT(wpipe->pipe_buffer.cnt <= 1242 wpipe->pipe_buffer.size, 1243 ("Pipe buffer overflow")); 1244 } 1245 pipeunlock(wpipe); 1246 if (error != 0) 1247 break; 1248 } else { 1249 /* 1250 * If the "read-side" has been blocked, wake it up now. 1251 */ 1252 if (wpipe->pipe_state & PIPE_WANTR) { 1253 wpipe->pipe_state &= ~PIPE_WANTR; 1254 wakeup(wpipe); 1255 } 1256 1257 /* 1258 * don't block on non-blocking I/O 1259 */ 1260 if (fp->f_flag & FNONBLOCK) { 1261 error = EAGAIN; 1262 pipeunlock(wpipe); 1263 break; 1264 } 1265 1266 /* 1267 * We have no more space and have something to offer, 1268 * wake up select/poll. 1269 */ 1270 pipeselwakeup(wpipe); 1271 1272 wpipe->pipe_state |= PIPE_WANTW; 1273 pipeunlock(wpipe); 1274 error = msleep(wpipe, PIPE_MTX(rpipe), 1275 PRIBIO | PCATCH, "pipewr", 0); 1276 if (error != 0) 1277 break; 1278 } 1279 } 1280 1281 pipelock(wpipe, 0); 1282 --wpipe->pipe_busy; 1283 1284 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 1285 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 1286 wakeup(wpipe); 1287 } else if (wpipe->pipe_buffer.cnt > 0) { 1288 /* 1289 * If we have put any characters in the buffer, we wake up 1290 * the reader. 1291 */ 1292 if (wpipe->pipe_state & PIPE_WANTR) { 1293 wpipe->pipe_state &= ~PIPE_WANTR; 1294 wakeup(wpipe); 1295 } 1296 } 1297 1298 /* 1299 * Don't return EPIPE if any byte was written. 1300 * EINTR and other interrupts are handled by generic I/O layer. 1301 * Do not pretend that I/O succeeded for obvious user error 1302 * like EFAULT. 1303 */ 1304 if (uio->uio_resid != orig_resid && error == EPIPE) 1305 error = 0; 1306 1307 if (error == 0) 1308 vfs_timestamp(&wpipe->pipe_mtime); 1309 1310 /* 1311 * We have something to offer, 1312 * wake up select/poll. 1313 */ 1314 if (wpipe->pipe_buffer.cnt) 1315 pipeselwakeup(wpipe); 1316 1317 pipeunlock(wpipe); 1318 PIPE_UNLOCK(rpipe); 1319 return (error); 1320 } 1321 1322 /* ARGSUSED */ 1323 static int 1324 pipe_truncate(fp, length, active_cred, td) 1325 struct file *fp; 1326 off_t length; 1327 struct ucred *active_cred; 1328 struct thread *td; 1329 { 1330 struct pipe *cpipe; 1331 int error; 1332 1333 cpipe = fp->f_data; 1334 if (cpipe->pipe_state & PIPE_NAMED) 1335 error = vnops.fo_truncate(fp, length, active_cred, td); 1336 else 1337 error = invfo_truncate(fp, length, active_cred, td); 1338 return (error); 1339 } 1340 1341 /* 1342 * we implement a very minimal set of ioctls for compatibility with sockets. 1343 */ 1344 static int 1345 pipe_ioctl(fp, cmd, data, active_cred, td) 1346 struct file *fp; 1347 u_long cmd; 1348 void *data; 1349 struct ucred *active_cred; 1350 struct thread *td; 1351 { 1352 struct pipe *mpipe = fp->f_data; 1353 int error; 1354 1355 PIPE_LOCK(mpipe); 1356 1357 #ifdef MAC 1358 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data); 1359 if (error) { 1360 PIPE_UNLOCK(mpipe); 1361 return (error); 1362 } 1363 #endif 1364 1365 error = 0; 1366 switch (cmd) { 1367 1368 case FIONBIO: 1369 break; 1370 1371 case FIOASYNC: 1372 if (*(int *)data) { 1373 mpipe->pipe_state |= PIPE_ASYNC; 1374 } else { 1375 mpipe->pipe_state &= ~PIPE_ASYNC; 1376 } 1377 break; 1378 1379 case FIONREAD: 1380 if (!(fp->f_flag & FREAD)) { 1381 *(int *)data = 0; 1382 PIPE_UNLOCK(mpipe); 1383 return (0); 1384 } 1385 if (mpipe->pipe_state & PIPE_DIRECTW) 1386 *(int *)data = mpipe->pipe_map.cnt; 1387 else 1388 *(int *)data = mpipe->pipe_buffer.cnt; 1389 break; 1390 1391 case FIOSETOWN: 1392 PIPE_UNLOCK(mpipe); 1393 error = fsetown(*(int *)data, &mpipe->pipe_sigio); 1394 goto out_unlocked; 1395 1396 case FIOGETOWN: 1397 *(int *)data = fgetown(&mpipe->pipe_sigio); 1398 break; 1399 1400 /* This is deprecated, FIOSETOWN should be used instead. */ 1401 case TIOCSPGRP: 1402 PIPE_UNLOCK(mpipe); 1403 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio); 1404 goto out_unlocked; 1405 1406 /* This is deprecated, FIOGETOWN should be used instead. */ 1407 case TIOCGPGRP: 1408 *(int *)data = -fgetown(&mpipe->pipe_sigio); 1409 break; 1410 1411 default: 1412 error = ENOTTY; 1413 break; 1414 } 1415 PIPE_UNLOCK(mpipe); 1416 out_unlocked: 1417 return (error); 1418 } 1419 1420 static int 1421 pipe_poll(fp, events, active_cred, td) 1422 struct file *fp; 1423 int events; 1424 struct ucred *active_cred; 1425 struct thread *td; 1426 { 1427 struct pipe *rpipe; 1428 struct pipe *wpipe; 1429 int levents, revents; 1430 #ifdef MAC 1431 int error; 1432 #endif 1433 1434 revents = 0; 1435 rpipe = fp->f_data; 1436 wpipe = PIPE_PEER(rpipe); 1437 PIPE_LOCK(rpipe); 1438 #ifdef MAC 1439 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair); 1440 if (error) 1441 goto locked_error; 1442 #endif 1443 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) 1444 if ((rpipe->pipe_state & PIPE_DIRECTW) || 1445 (rpipe->pipe_buffer.cnt > 0)) 1446 revents |= events & (POLLIN | POLLRDNORM); 1447 1448 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) 1449 if (wpipe->pipe_present != PIPE_ACTIVE || 1450 (wpipe->pipe_state & PIPE_EOF) || 1451 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) && 1452 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF || 1453 wpipe->pipe_buffer.size == 0))) 1454 revents |= events & (POLLOUT | POLLWRNORM); 1455 1456 levents = events & 1457 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND); 1458 if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents && 1459 fp->f_seqcount == rpipe->pipe_wgen) 1460 events |= POLLINIGNEOF; 1461 1462 if ((events & POLLINIGNEOF) == 0) { 1463 if (rpipe->pipe_state & PIPE_EOF) { 1464 revents |= (events & (POLLIN | POLLRDNORM)); 1465 if (wpipe->pipe_present != PIPE_ACTIVE || 1466 (wpipe->pipe_state & PIPE_EOF)) 1467 revents |= POLLHUP; 1468 } 1469 } 1470 1471 if (revents == 0) { 1472 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) { 1473 selrecord(td, &rpipe->pipe_sel); 1474 if (SEL_WAITING(&rpipe->pipe_sel)) 1475 rpipe->pipe_state |= PIPE_SEL; 1476 } 1477 1478 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) { 1479 selrecord(td, &wpipe->pipe_sel); 1480 if (SEL_WAITING(&wpipe->pipe_sel)) 1481 wpipe->pipe_state |= PIPE_SEL; 1482 } 1483 } 1484 #ifdef MAC 1485 locked_error: 1486 #endif 1487 PIPE_UNLOCK(rpipe); 1488 1489 return (revents); 1490 } 1491 1492 /* 1493 * We shouldn't need locks here as we're doing a read and this should 1494 * be a natural race. 1495 */ 1496 static int 1497 pipe_stat(fp, ub, active_cred, td) 1498 struct file *fp; 1499 struct stat *ub; 1500 struct ucred *active_cred; 1501 struct thread *td; 1502 { 1503 struct pipe *pipe; 1504 int new_unr; 1505 #ifdef MAC 1506 int error; 1507 #endif 1508 1509 pipe = fp->f_data; 1510 PIPE_LOCK(pipe); 1511 #ifdef MAC 1512 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair); 1513 if (error) { 1514 PIPE_UNLOCK(pipe); 1515 return (error); 1516 } 1517 #endif 1518 1519 /* For named pipes ask the underlying filesystem. */ 1520 if (pipe->pipe_state & PIPE_NAMED) { 1521 PIPE_UNLOCK(pipe); 1522 return (vnops.fo_stat(fp, ub, active_cred, td)); 1523 } 1524 1525 /* 1526 * Lazily allocate an inode number for the pipe. Most pipe 1527 * users do not call fstat(2) on the pipe, which means that 1528 * postponing the inode allocation until it is must be 1529 * returned to userland is useful. If alloc_unr failed, 1530 * assign st_ino zero instead of returning an error. 1531 * Special pipe_ino values: 1532 * -1 - not yet initialized; 1533 * 0 - alloc_unr failed, return 0 as st_ino forever. 1534 */ 1535 if (pipe->pipe_ino == (ino_t)-1) { 1536 new_unr = alloc_unr(pipeino_unr); 1537 if (new_unr != -1) 1538 pipe->pipe_ino = new_unr; 1539 else 1540 pipe->pipe_ino = 0; 1541 } 1542 PIPE_UNLOCK(pipe); 1543 1544 bzero(ub, sizeof(*ub)); 1545 ub->st_mode = S_IFIFO; 1546 ub->st_blksize = PAGE_SIZE; 1547 if (pipe->pipe_state & PIPE_DIRECTW) 1548 ub->st_size = pipe->pipe_map.cnt; 1549 else 1550 ub->st_size = pipe->pipe_buffer.cnt; 1551 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize; 1552 ub->st_atim = pipe->pipe_atime; 1553 ub->st_mtim = pipe->pipe_mtime; 1554 ub->st_ctim = pipe->pipe_ctime; 1555 ub->st_uid = fp->f_cred->cr_uid; 1556 ub->st_gid = fp->f_cred->cr_gid; 1557 ub->st_dev = pipedev_ino; 1558 ub->st_ino = pipe->pipe_ino; 1559 /* 1560 * Left as 0: st_nlink, st_rdev, st_flags, st_gen. 1561 */ 1562 return (0); 1563 } 1564 1565 /* ARGSUSED */ 1566 static int 1567 pipe_close(fp, td) 1568 struct file *fp; 1569 struct thread *td; 1570 { 1571 1572 if (fp->f_vnode != NULL) 1573 return vnops.fo_close(fp, td); 1574 fp->f_ops = &badfileops; 1575 pipe_dtor(fp->f_data); 1576 fp->f_data = NULL; 1577 return (0); 1578 } 1579 1580 static int 1581 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td) 1582 { 1583 struct pipe *cpipe; 1584 int error; 1585 1586 cpipe = fp->f_data; 1587 if (cpipe->pipe_state & PIPE_NAMED) 1588 error = vn_chmod(fp, mode, active_cred, td); 1589 else 1590 error = invfo_chmod(fp, mode, active_cred, td); 1591 return (error); 1592 } 1593 1594 static int 1595 pipe_chown(fp, uid, gid, active_cred, td) 1596 struct file *fp; 1597 uid_t uid; 1598 gid_t gid; 1599 struct ucred *active_cred; 1600 struct thread *td; 1601 { 1602 struct pipe *cpipe; 1603 int error; 1604 1605 cpipe = fp->f_data; 1606 if (cpipe->pipe_state & PIPE_NAMED) 1607 error = vn_chown(fp, uid, gid, active_cred, td); 1608 else 1609 error = invfo_chown(fp, uid, gid, active_cred, td); 1610 return (error); 1611 } 1612 1613 static int 1614 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp) 1615 { 1616 struct pipe *pi; 1617 1618 if (fp->f_type == DTYPE_FIFO) 1619 return (vn_fill_kinfo(fp, kif, fdp)); 1620 kif->kf_type = KF_TYPE_PIPE; 1621 pi = fp->f_data; 1622 kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi; 1623 kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer; 1624 kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt; 1625 return (0); 1626 } 1627 1628 static void 1629 pipe_free_kmem(cpipe) 1630 struct pipe *cpipe; 1631 { 1632 1633 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), 1634 ("pipe_free_kmem: pipe mutex locked")); 1635 1636 if (cpipe->pipe_buffer.buffer != NULL) { 1637 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size); 1638 vm_map_remove(pipe_map, 1639 (vm_offset_t)cpipe->pipe_buffer.buffer, 1640 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size); 1641 cpipe->pipe_buffer.buffer = NULL; 1642 } 1643 #ifndef PIPE_NODIRECT 1644 { 1645 cpipe->pipe_map.cnt = 0; 1646 cpipe->pipe_map.pos = 0; 1647 cpipe->pipe_map.npages = 0; 1648 } 1649 #endif 1650 } 1651 1652 /* 1653 * shutdown the pipe 1654 */ 1655 static void 1656 pipeclose(cpipe) 1657 struct pipe *cpipe; 1658 { 1659 struct pipepair *pp; 1660 struct pipe *ppipe; 1661 1662 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL")); 1663 1664 PIPE_LOCK(cpipe); 1665 pipelock(cpipe, 0); 1666 pp = cpipe->pipe_pair; 1667 1668 pipeselwakeup(cpipe); 1669 1670 /* 1671 * If the other side is blocked, wake it up saying that 1672 * we want to close it down. 1673 */ 1674 cpipe->pipe_state |= PIPE_EOF; 1675 while (cpipe->pipe_busy) { 1676 wakeup(cpipe); 1677 cpipe->pipe_state |= PIPE_WANT; 1678 pipeunlock(cpipe); 1679 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0); 1680 pipelock(cpipe, 0); 1681 } 1682 1683 1684 /* 1685 * Disconnect from peer, if any. 1686 */ 1687 ppipe = cpipe->pipe_peer; 1688 if (ppipe->pipe_present == PIPE_ACTIVE) { 1689 pipeselwakeup(ppipe); 1690 1691 ppipe->pipe_state |= PIPE_EOF; 1692 wakeup(ppipe); 1693 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0); 1694 } 1695 1696 /* 1697 * Mark this endpoint as free. Release kmem resources. We 1698 * don't mark this endpoint as unused until we've finished 1699 * doing that, or the pipe might disappear out from under 1700 * us. 1701 */ 1702 PIPE_UNLOCK(cpipe); 1703 pipe_free_kmem(cpipe); 1704 PIPE_LOCK(cpipe); 1705 cpipe->pipe_present = PIPE_CLOSING; 1706 pipeunlock(cpipe); 1707 1708 /* 1709 * knlist_clear() may sleep dropping the PIPE_MTX. Set the 1710 * PIPE_FINALIZED, that allows other end to free the 1711 * pipe_pair, only after the knotes are completely dismantled. 1712 */ 1713 knlist_clear(&cpipe->pipe_sel.si_note, 1); 1714 cpipe->pipe_present = PIPE_FINALIZED; 1715 seldrain(&cpipe->pipe_sel); 1716 knlist_destroy(&cpipe->pipe_sel.si_note); 1717 1718 /* 1719 * If both endpoints are now closed, release the memory for the 1720 * pipe pair. If not, unlock. 1721 */ 1722 if (ppipe->pipe_present == PIPE_FINALIZED) { 1723 PIPE_UNLOCK(cpipe); 1724 #ifdef MAC 1725 mac_pipe_destroy(pp); 1726 #endif 1727 uma_zfree(pipe_zone, cpipe->pipe_pair); 1728 } else 1729 PIPE_UNLOCK(cpipe); 1730 } 1731 1732 /*ARGSUSED*/ 1733 static int 1734 pipe_kqfilter(struct file *fp, struct knote *kn) 1735 { 1736 struct pipe *cpipe; 1737 1738 /* 1739 * If a filter is requested that is not supported by this file 1740 * descriptor, don't return an error, but also don't ever generate an 1741 * event. 1742 */ 1743 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) { 1744 kn->kn_fop = &pipe_nfiltops; 1745 return (0); 1746 } 1747 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) { 1748 kn->kn_fop = &pipe_nfiltops; 1749 return (0); 1750 } 1751 cpipe = fp->f_data; 1752 PIPE_LOCK(cpipe); 1753 switch (kn->kn_filter) { 1754 case EVFILT_READ: 1755 kn->kn_fop = &pipe_rfiltops; 1756 break; 1757 case EVFILT_WRITE: 1758 kn->kn_fop = &pipe_wfiltops; 1759 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) { 1760 /* other end of pipe has been closed */ 1761 PIPE_UNLOCK(cpipe); 1762 return (EPIPE); 1763 } 1764 cpipe = PIPE_PEER(cpipe); 1765 break; 1766 default: 1767 PIPE_UNLOCK(cpipe); 1768 return (EINVAL); 1769 } 1770 1771 kn->kn_hook = cpipe; 1772 knlist_add(&cpipe->pipe_sel.si_note, kn, 1); 1773 PIPE_UNLOCK(cpipe); 1774 return (0); 1775 } 1776 1777 static void 1778 filt_pipedetach(struct knote *kn) 1779 { 1780 struct pipe *cpipe = kn->kn_hook; 1781 1782 PIPE_LOCK(cpipe); 1783 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1); 1784 PIPE_UNLOCK(cpipe); 1785 } 1786 1787 /*ARGSUSED*/ 1788 static int 1789 filt_piperead(struct knote *kn, long hint) 1790 { 1791 struct pipe *rpipe = kn->kn_hook; 1792 struct pipe *wpipe = rpipe->pipe_peer; 1793 int ret; 1794 1795 PIPE_LOCK(rpipe); 1796 kn->kn_data = rpipe->pipe_buffer.cnt; 1797 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) 1798 kn->kn_data = rpipe->pipe_map.cnt; 1799 1800 if ((rpipe->pipe_state & PIPE_EOF) || 1801 wpipe->pipe_present != PIPE_ACTIVE || 1802 (wpipe->pipe_state & PIPE_EOF)) { 1803 kn->kn_flags |= EV_EOF; 1804 PIPE_UNLOCK(rpipe); 1805 return (1); 1806 } 1807 ret = kn->kn_data > 0; 1808 PIPE_UNLOCK(rpipe); 1809 return ret; 1810 } 1811 1812 /*ARGSUSED*/ 1813 static int 1814 filt_pipewrite(struct knote *kn, long hint) 1815 { 1816 struct pipe *wpipe; 1817 1818 wpipe = kn->kn_hook; 1819 PIPE_LOCK(wpipe); 1820 if (wpipe->pipe_present != PIPE_ACTIVE || 1821 (wpipe->pipe_state & PIPE_EOF)) { 1822 kn->kn_data = 0; 1823 kn->kn_flags |= EV_EOF; 1824 PIPE_UNLOCK(wpipe); 1825 return (1); 1826 } 1827 kn->kn_data = (wpipe->pipe_buffer.size > 0) ? 1828 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF; 1829 if (wpipe->pipe_state & PIPE_DIRECTW) 1830 kn->kn_data = 0; 1831 1832 PIPE_UNLOCK(wpipe); 1833 return (kn->kn_data >= PIPE_BUF); 1834 } 1835 1836 static void 1837 filt_pipedetach_notsup(struct knote *kn) 1838 { 1839 1840 } 1841 1842 static int 1843 filt_pipenotsup(struct knote *kn, long hint) 1844 { 1845 1846 return (0); 1847 } 1848