20 */ 21 22/* 23 * This file contains a high-performance replacement for the socket-based 24 * pipes scheme originally used in FreeBSD/4.4Lite. It does not support 25 * all features of sockets, but does do everything that pipes normally 26 * do. 27 */ 28 29/* 30 * This code has two modes of operation, a small write mode and a large 31 * write mode. The small write mode acts like conventional pipes with 32 * a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the 33 * "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT 34 * and PIPE_SIZE in size, it is fully mapped and wired into the kernel, and 35 * the receiving process can copy it directly from the pages in the sending 36 * process. 37 * 38 * If the sending process receives a signal, it is possible that it will 39 * go away, and certainly its address space can change, because control 40 * is returned back to the user-mode side. In that case, the pipe code 41 * arranges to copy the buffer supplied by the user process, to a pageable 42 * kernel buffer, and the receiving process will grab the data from the 43 * pageable kernel buffer. Since signals don't happen all that often, 44 * the copy operation is normally eliminated. 45 * 46 * The constant PIPE_MINDIRECT is chosen to make sure that buffering will 47 * happen for small transfers so that the system will not spend all of 48 * its time context switching. PIPE_SIZE is constrained by the 49 * amount of kernel virtual memory. 50 */ 51 52#include <sys/param.h> 53#include <sys/systm.h> 54#include <sys/fcntl.h> 55#include <sys/file.h> 56#include <sys/filedesc.h> 57#include <sys/filio.h> 58#include <sys/kernel.h> 59#include <sys/lock.h> 60#include <sys/mutex.h> 61#include <sys/ttycom.h> 62#include <sys/stat.h> 63#include <sys/malloc.h> 64#include <sys/poll.h> 65#include <sys/selinfo.h> 66#include <sys/signalvar.h> 67#include <sys/sysproto.h> 68#include <sys/pipe.h> 69#include <sys/proc.h> 70#include <sys/vnode.h> 71#include <sys/uio.h> 72#include <sys/event.h> 73 74#include <vm/vm.h> 75#include <vm/vm_param.h> 76#include <vm/vm_object.h> 77#include <vm/vm_kern.h> 78#include <vm/vm_extern.h> 79#include <vm/pmap.h> 80#include <vm/vm_map.h> 81#include <vm/vm_page.h> 82#include <vm/vm_zone.h> 83 84/* 85 * Use this define if you want to disable *fancy* VM things. Expect an 86 * approx 30% decrease in transfer rate. This could be useful for 87 * NetBSD or OpenBSD. 88 */ 89/* #define PIPE_NODIRECT */ 90 91/* 92 * interfaces to the outside world 93 */ 94static int pipe_read(struct file *fp, struct uio *uio, 95 struct ucred *cred, int flags, struct thread *td); 96static int pipe_write(struct file *fp, struct uio *uio, 97 struct ucred *cred, int flags, struct thread *td); 98static int pipe_close(struct file *fp, struct thread *td); 99static int pipe_poll(struct file *fp, int events, struct ucred *cred, 100 struct thread *td); 101static int pipe_kqfilter(struct file *fp, struct knote *kn); 102static int pipe_stat(struct file *fp, struct stat *sb, struct thread *td); 103static int pipe_ioctl(struct file *fp, u_long cmd, caddr_t data, struct thread *td); 104 105static struct fileops pipeops = { 106 pipe_read, pipe_write, pipe_ioctl, pipe_poll, pipe_kqfilter, 107 pipe_stat, pipe_close 108}; 109 110static void filt_pipedetach(struct knote *kn); 111static int filt_piperead(struct knote *kn, long hint); 112static int filt_pipewrite(struct knote *kn, long hint); 113 114static struct filterops pipe_rfiltops = 115 { 1, NULL, filt_pipedetach, filt_piperead }; 116static struct filterops pipe_wfiltops = 117 { 1, NULL, filt_pipedetach, filt_pipewrite }; 118 119#define PIPE_GET_GIANT(pipe) \ 120 do { \ 121 KASSERT(((pipe)->pipe_state & PIPE_LOCKFL) != 0, \ 122 ("%s:%d PIPE_GET_GIANT: line pipe not locked", \ 123 __FILE__, __LINE__)); \ 124 PIPE_UNLOCK(pipe); \ 125 mtx_lock(&Giant); \ 126 } while (0) 127 128#define PIPE_DROP_GIANT(pipe) \ 129 do { \ 130 mtx_unlock(&Giant); \ 131 PIPE_LOCK(pipe); \ 132 } while (0) 133 134/* 135 * Default pipe buffer size(s), this can be kind-of large now because pipe 136 * space is pageable. The pipe code will try to maintain locality of 137 * reference for performance reasons, so small amounts of outstanding I/O 138 * will not wipe the cache. 139 */ 140#define MINPIPESIZE (PIPE_SIZE/3) 141#define MAXPIPESIZE (2*PIPE_SIZE/3) 142 143/* 144 * Maximum amount of kva for pipes -- this is kind-of a soft limit, but 145 * is there so that on large systems, we don't exhaust it. 146 */ 147#define MAXPIPEKVA (8*1024*1024) 148 149/* 150 * Limit for direct transfers, we cannot, of course limit 151 * the amount of kva for pipes in general though. 152 */ 153#define LIMITPIPEKVA (16*1024*1024) 154 155/* 156 * Limit the number of "big" pipes 157 */ 158#define LIMITBIGPIPES 32 159static int nbigpipe; 160 161static int amountpipekva; 162 163static void pipeinit(void *dummy __unused); 164static void pipeclose(struct pipe *cpipe); 165static void pipe_free_kmem(struct pipe *cpipe); 166static int pipe_create(struct pipe **cpipep); 167static __inline int pipelock(struct pipe *cpipe, int catch); 168static __inline void pipeunlock(struct pipe *cpipe); 169static __inline void pipeselwakeup(struct pipe *cpipe); 170#ifndef PIPE_NODIRECT 171static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio); 172static void pipe_destroy_write_buffer(struct pipe *wpipe); 173static int pipe_direct_write(struct pipe *wpipe, struct uio *uio); 174static void pipe_clone_write_buffer(struct pipe *wpipe); 175#endif 176static int pipespace(struct pipe *cpipe, int size); 177 178static vm_zone_t pipe_zone; 179 180SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL); 181 182static void 183pipeinit(void *dummy __unused) 184{
|
187} 188 189/* 190 * The pipe system call for the DTYPE_PIPE type of pipes 191 */ 192 193/* ARGSUSED */ 194int 195pipe(td, uap) 196 struct thread *td; 197 struct pipe_args /* { 198 int dummy; 199 } */ *uap; 200{ 201 struct filedesc *fdp = td->td_proc->p_fd; 202 struct file *rf, *wf; 203 struct pipe *rpipe, *wpipe; 204 struct mtx *pmtx; 205 int fd, error; 206 207 KASSERT(pipe_zone != NULL, ("pipe_zone not initialized")); 208 209 pmtx = malloc(sizeof(*pmtx), M_TEMP, M_WAITOK | M_ZERO); 210 211 rpipe = wpipe = NULL; 212 if (pipe_create(&rpipe) || pipe_create(&wpipe)) { 213 pipeclose(rpipe); 214 pipeclose(wpipe); 215 free(pmtx, M_TEMP); 216 return (ENFILE); 217 } 218 219 rpipe->pipe_state |= PIPE_DIRECTOK; 220 wpipe->pipe_state |= PIPE_DIRECTOK; 221 222 error = falloc(td, &rf, &fd); 223 if (error) { 224 pipeclose(rpipe); 225 pipeclose(wpipe); 226 free(pmtx, M_TEMP); 227 return (error); 228 } 229 fhold(rf); 230 td->td_retval[0] = fd; 231 232 /* 233 * Warning: once we've gotten past allocation of the fd for the 234 * read-side, we can only drop the read side via fdrop() in order 235 * to avoid races against processes which manage to dup() the read 236 * side while we are blocked trying to allocate the write side. 237 */ 238 FILE_LOCK(rf); 239 rf->f_flag = FREAD | FWRITE; 240 rf->f_type = DTYPE_PIPE; 241 rf->f_data = (caddr_t)rpipe; 242 rf->f_ops = &pipeops; 243 FILE_UNLOCK(rf); 244 error = falloc(td, &wf, &fd); 245 if (error) { 246 FILEDESC_LOCK(fdp); 247 if (fdp->fd_ofiles[td->td_retval[0]] == rf) { 248 fdp->fd_ofiles[td->td_retval[0]] = NULL; 249 FILEDESC_UNLOCK(fdp); 250 fdrop(rf, td); 251 } else 252 FILEDESC_UNLOCK(fdp); 253 fdrop(rf, td); 254 /* rpipe has been closed by fdrop(). */ 255 pipeclose(wpipe); 256 free(pmtx, M_TEMP); 257 return (error); 258 } 259 FILE_LOCK(wf); 260 wf->f_flag = FREAD | FWRITE; 261 wf->f_type = DTYPE_PIPE; 262 wf->f_data = (caddr_t)wpipe; 263 wf->f_ops = &pipeops; 264 FILE_UNLOCK(wf); 265 td->td_retval[1] = fd; 266 rpipe->pipe_peer = wpipe; 267 wpipe->pipe_peer = rpipe; 268 mtx_init(pmtx, "pipe mutex", MTX_DEF); 269 rpipe->pipe_mtxp = wpipe->pipe_mtxp = pmtx; 270 fdrop(rf, td); 271 272 return (0); 273} 274 275/* 276 * Allocate kva for pipe circular buffer, the space is pageable 277 * This routine will 'realloc' the size of a pipe safely, if it fails 278 * it will retain the old buffer. 279 * If it fails it will return ENOMEM. 280 */ 281static int 282pipespace(cpipe, size) 283 struct pipe *cpipe; 284 int size; 285{ 286 struct vm_object *object; 287 caddr_t buffer; 288 int npages, error; 289 290 GIANT_REQUIRED; 291 KASSERT(cpipe->pipe_mtxp == NULL || !mtx_owned(PIPE_MTX(cpipe)), 292 ("pipespace: pipe mutex locked")); 293 294 npages = round_page(size)/PAGE_SIZE; 295 /* 296 * Create an object, I don't like the idea of paging to/from 297 * kernel_object. 298 * XXX -- minor change needed here for NetBSD/OpenBSD VM systems. 299 */ 300 object = vm_object_allocate(OBJT_DEFAULT, npages); 301 buffer = (caddr_t) vm_map_min(kernel_map); 302 303 /* 304 * Insert the object into the kernel map, and allocate kva for it. 305 * The map entry is, by default, pageable. 306 * XXX -- minor change needed here for NetBSD/OpenBSD VM systems. 307 */ 308 error = vm_map_find(kernel_map, object, 0, 309 (vm_offset_t *) &buffer, size, 1, 310 VM_PROT_ALL, VM_PROT_ALL, 0); 311 312 if (error != KERN_SUCCESS) { 313 vm_object_deallocate(object); 314 return (ENOMEM); 315 } 316 317 /* free old resources if we're resizing */ 318 pipe_free_kmem(cpipe); 319 cpipe->pipe_buffer.object = object; 320 cpipe->pipe_buffer.buffer = buffer; 321 cpipe->pipe_buffer.size = size; 322 cpipe->pipe_buffer.in = 0; 323 cpipe->pipe_buffer.out = 0; 324 cpipe->pipe_buffer.cnt = 0; 325 amountpipekva += cpipe->pipe_buffer.size; 326 return (0); 327} 328 329/* 330 * initialize and allocate VM and memory for pipe 331 */ 332static int 333pipe_create(cpipep) 334 struct pipe **cpipep; 335{ 336 struct pipe *cpipe; 337 int error; 338 339 *cpipep = zalloc(pipe_zone); 340 if (*cpipep == NULL) 341 return (ENOMEM); 342 343 cpipe = *cpipep; 344 345 /* so pipespace()->pipe_free_kmem() doesn't follow junk pointer */ 346 cpipe->pipe_buffer.object = NULL; 347#ifndef PIPE_NODIRECT 348 cpipe->pipe_map.kva = NULL; 349#endif 350 /* 351 * protect so pipeclose() doesn't follow a junk pointer 352 * if pipespace() fails. 353 */ 354 bzero(&cpipe->pipe_sel, sizeof(cpipe->pipe_sel)); 355 cpipe->pipe_state = 0; 356 cpipe->pipe_peer = NULL; 357 cpipe->pipe_busy = 0; 358 359#ifndef PIPE_NODIRECT 360 /* 361 * pipe data structure initializations to support direct pipe I/O 362 */ 363 cpipe->pipe_map.cnt = 0; 364 cpipe->pipe_map.kva = 0; 365 cpipe->pipe_map.pos = 0; 366 cpipe->pipe_map.npages = 0; 367 /* cpipe->pipe_map.ms[] = invalid */ 368#endif 369 370 cpipe->pipe_mtxp = NULL; /* avoid pipespace assertion */ 371 error = pipespace(cpipe, PIPE_SIZE); 372 if (error) 373 return (error); 374 375 vfs_timestamp(&cpipe->pipe_ctime); 376 cpipe->pipe_atime = cpipe->pipe_ctime; 377 cpipe->pipe_mtime = cpipe->pipe_ctime; 378 379 return (0); 380} 381 382 383/* 384 * lock a pipe for I/O, blocking other access 385 */ 386static __inline int 387pipelock(cpipe, catch) 388 struct pipe *cpipe; 389 int catch; 390{ 391 int error; 392 393 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 394 while (cpipe->pipe_state & PIPE_LOCKFL) { 395 cpipe->pipe_state |= PIPE_LWANT; 396 error = msleep(cpipe, PIPE_MTX(cpipe), 397 catch ? (PRIBIO | PCATCH) : PRIBIO, 398 "pipelk", 0); 399 if (error != 0) 400 return (error); 401 } 402 cpipe->pipe_state |= PIPE_LOCKFL; 403 return (0); 404} 405 406/* 407 * unlock a pipe I/O lock 408 */ 409static __inline void 410pipeunlock(cpipe) 411 struct pipe *cpipe; 412{ 413 414 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 415 cpipe->pipe_state &= ~PIPE_LOCKFL; 416 if (cpipe->pipe_state & PIPE_LWANT) { 417 cpipe->pipe_state &= ~PIPE_LWANT; 418 wakeup(cpipe); 419 } 420} 421 422static __inline void 423pipeselwakeup(cpipe) 424 struct pipe *cpipe; 425{ 426 427 if (cpipe->pipe_state & PIPE_SEL) { 428 cpipe->pipe_state &= ~PIPE_SEL; 429 selwakeup(&cpipe->pipe_sel); 430 } 431 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) 432 pgsigio(cpipe->pipe_sigio, SIGIO, 0); 433 KNOTE(&cpipe->pipe_sel.si_note, 0); 434} 435 436/* ARGSUSED */ 437static int 438pipe_read(fp, uio, cred, flags, td) 439 struct file *fp; 440 struct uio *uio; 441 struct ucred *cred; 442 struct thread *td; 443 int flags; 444{ 445 struct pipe *rpipe = (struct pipe *) fp->f_data; 446 int error; 447 int nread = 0; 448 u_int size; 449 450 PIPE_LOCK(rpipe); 451 ++rpipe->pipe_busy; 452 error = pipelock(rpipe, 1); 453 if (error) 454 goto unlocked_error; 455 456 while (uio->uio_resid) { 457 /* 458 * normal pipe buffer receive 459 */ 460 if (rpipe->pipe_buffer.cnt > 0) { 461 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 462 if (size > rpipe->pipe_buffer.cnt) 463 size = rpipe->pipe_buffer.cnt; 464 if (size > (u_int) uio->uio_resid) 465 size = (u_int) uio->uio_resid; 466 467 PIPE_UNLOCK(rpipe); 468 error = uiomove(&rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 469 size, uio); 470 PIPE_LOCK(rpipe); 471 if (error) 472 break; 473 474 rpipe->pipe_buffer.out += size; 475 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 476 rpipe->pipe_buffer.out = 0; 477 478 rpipe->pipe_buffer.cnt -= size; 479 480 /* 481 * If there is no more to read in the pipe, reset 482 * its pointers to the beginning. This improves 483 * cache hit stats. 484 */ 485 if (rpipe->pipe_buffer.cnt == 0) { 486 rpipe->pipe_buffer.in = 0; 487 rpipe->pipe_buffer.out = 0; 488 } 489 nread += size; 490#ifndef PIPE_NODIRECT 491 /* 492 * Direct copy, bypassing a kernel buffer. 493 */ 494 } else if ((size = rpipe->pipe_map.cnt) && 495 (rpipe->pipe_state & PIPE_DIRECTW)) { 496 caddr_t va; 497 if (size > (u_int) uio->uio_resid) 498 size = (u_int) uio->uio_resid; 499 500 va = (caddr_t) rpipe->pipe_map.kva + 501 rpipe->pipe_map.pos; 502 PIPE_UNLOCK(rpipe); 503 error = uiomove(va, size, uio); 504 PIPE_LOCK(rpipe); 505 if (error) 506 break; 507 nread += size; 508 rpipe->pipe_map.pos += size; 509 rpipe->pipe_map.cnt -= size; 510 if (rpipe->pipe_map.cnt == 0) { 511 rpipe->pipe_state &= ~PIPE_DIRECTW; 512 wakeup(rpipe); 513 } 514#endif 515 } else { 516 /* 517 * detect EOF condition 518 * read returns 0 on EOF, no need to set error 519 */ 520 if (rpipe->pipe_state & PIPE_EOF) 521 break; 522 523 /* 524 * If the "write-side" has been blocked, wake it up now. 525 */ 526 if (rpipe->pipe_state & PIPE_WANTW) { 527 rpipe->pipe_state &= ~PIPE_WANTW; 528 wakeup(rpipe); 529 } 530 531 /* 532 * Break if some data was read. 533 */ 534 if (nread > 0) 535 break; 536 537 /* 538 * Unlock the pipe buffer for our remaining processing. We 539 * will either break out with an error or we will sleep and 540 * relock to loop. 541 */ 542 pipeunlock(rpipe); 543 544 /* 545 * Handle non-blocking mode operation or 546 * wait for more data. 547 */ 548 if (fp->f_flag & FNONBLOCK) { 549 error = EAGAIN; 550 } else { 551 rpipe->pipe_state |= PIPE_WANTR; 552 if ((error = msleep(rpipe, PIPE_MTX(rpipe), 553 PRIBIO | PCATCH, 554 "piperd", 0)) == 0) 555 error = pipelock(rpipe, 1); 556 } 557 if (error) 558 goto unlocked_error; 559 } 560 } 561 pipeunlock(rpipe); 562 563 /* XXX: should probably do this before getting any locks. */ 564 if (error == 0) 565 vfs_timestamp(&rpipe->pipe_atime); 566unlocked_error: 567 --rpipe->pipe_busy; 568 569 /* 570 * PIPE_WANT processing only makes sense if pipe_busy is 0. 571 */ 572 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 573 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 574 wakeup(rpipe); 575 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 576 /* 577 * Handle write blocking hysteresis. 578 */ 579 if (rpipe->pipe_state & PIPE_WANTW) { 580 rpipe->pipe_state &= ~PIPE_WANTW; 581 wakeup(rpipe); 582 } 583 } 584 585 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF) 586 pipeselwakeup(rpipe); 587 588 PIPE_UNLOCK(rpipe); 589 return (error); 590} 591 592#ifndef PIPE_NODIRECT 593/* 594 * Map the sending processes' buffer into kernel space and wire it. 595 * This is similar to a physical write operation. 596 */ 597static int 598pipe_build_write_buffer(wpipe, uio) 599 struct pipe *wpipe; 600 struct uio *uio; 601{ 602 u_int size; 603 int i; 604 vm_offset_t addr, endaddr, paddr; 605 606 GIANT_REQUIRED; 607 PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED); 608 609 size = (u_int) uio->uio_iov->iov_len; 610 if (size > wpipe->pipe_buffer.size) 611 size = wpipe->pipe_buffer.size; 612 613 endaddr = round_page((vm_offset_t)uio->uio_iov->iov_base + size); 614 addr = trunc_page((vm_offset_t)uio->uio_iov->iov_base); 615 for (i = 0; addr < endaddr; addr += PAGE_SIZE, i++) { 616 vm_page_t m; 617 618 if (vm_fault_quick((caddr_t)addr, VM_PROT_READ) < 0 || 619 (paddr = pmap_kextract(addr)) == 0) { 620 int j; 621 622 for (j = 0; j < i; j++) 623 vm_page_unwire(wpipe->pipe_map.ms[j], 1); 624 return (EFAULT); 625 } 626 627 m = PHYS_TO_VM_PAGE(paddr); 628 vm_page_wire(m); 629 wpipe->pipe_map.ms[i] = m; 630 } 631 632/* 633 * set up the control block 634 */ 635 wpipe->pipe_map.npages = i; 636 wpipe->pipe_map.pos = 637 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 638 wpipe->pipe_map.cnt = size; 639 640/* 641 * and map the buffer 642 */ 643 if (wpipe->pipe_map.kva == 0) { 644 /* 645 * We need to allocate space for an extra page because the 646 * address range might (will) span pages at times. 647 */ 648 wpipe->pipe_map.kva = kmem_alloc_pageable(kernel_map, 649 wpipe->pipe_buffer.size + PAGE_SIZE); 650 amountpipekva += wpipe->pipe_buffer.size + PAGE_SIZE; 651 } 652 pmap_qenter(wpipe->pipe_map.kva, wpipe->pipe_map.ms, 653 wpipe->pipe_map.npages); 654 655/* 656 * and update the uio data 657 */ 658 659 uio->uio_iov->iov_len -= size; 660 uio->uio_iov->iov_base += size; 661 if (uio->uio_iov->iov_len == 0) 662 uio->uio_iov++; 663 uio->uio_resid -= size; 664 uio->uio_offset += size; 665 return (0); 666} 667 668/* 669 * unmap and unwire the process buffer 670 */ 671static void 672pipe_destroy_write_buffer(wpipe) 673 struct pipe *wpipe; 674{ 675 int i; 676 677 GIANT_REQUIRED; 678 PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED); 679 680 if (wpipe->pipe_map.kva) { 681 pmap_qremove(wpipe->pipe_map.kva, wpipe->pipe_map.npages); 682 683 if (amountpipekva > MAXPIPEKVA) { 684 vm_offset_t kva = wpipe->pipe_map.kva; 685 wpipe->pipe_map.kva = 0; 686 kmem_free(kernel_map, kva, 687 wpipe->pipe_buffer.size + PAGE_SIZE); 688 amountpipekva -= wpipe->pipe_buffer.size + PAGE_SIZE; 689 } 690 } 691 for (i = 0; i < wpipe->pipe_map.npages; i++) 692 vm_page_unwire(wpipe->pipe_map.ms[i], 1); 693 wpipe->pipe_map.npages = 0; 694} 695 696/* 697 * In the case of a signal, the writing process might go away. This 698 * code copies the data into the circular buffer so that the source 699 * pages can be freed without loss of data. 700 */ 701static void 702pipe_clone_write_buffer(wpipe) 703 struct pipe *wpipe; 704{ 705 int size; 706 int pos; 707 708 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 709 size = wpipe->pipe_map.cnt; 710 pos = wpipe->pipe_map.pos; 711 bcopy((caddr_t) wpipe->pipe_map.kva + pos, 712 (caddr_t) wpipe->pipe_buffer.buffer, size); 713 714 wpipe->pipe_buffer.in = size; 715 wpipe->pipe_buffer.out = 0; 716 wpipe->pipe_buffer.cnt = size; 717 wpipe->pipe_state &= ~PIPE_DIRECTW; 718 719 PIPE_GET_GIANT(wpipe); 720 pipe_destroy_write_buffer(wpipe); 721 PIPE_DROP_GIANT(wpipe); 722} 723 724/* 725 * This implements the pipe buffer write mechanism. Note that only 726 * a direct write OR a normal pipe write can be pending at any given time. 727 * If there are any characters in the pipe buffer, the direct write will 728 * be deferred until the receiving process grabs all of the bytes from 729 * the pipe buffer. Then the direct mapping write is set-up. 730 */ 731static int 732pipe_direct_write(wpipe, uio) 733 struct pipe *wpipe; 734 struct uio *uio; 735{ 736 int error; 737 738retry: 739 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 740 while (wpipe->pipe_state & PIPE_DIRECTW) { 741 if (wpipe->pipe_state & PIPE_WANTR) { 742 wpipe->pipe_state &= ~PIPE_WANTR; 743 wakeup(wpipe); 744 } 745 wpipe->pipe_state |= PIPE_WANTW; 746 error = msleep(wpipe, PIPE_MTX(wpipe), 747 PRIBIO | PCATCH, "pipdww", 0); 748 if (error) 749 goto error1; 750 if (wpipe->pipe_state & PIPE_EOF) { 751 error = EPIPE; 752 goto error1; 753 } 754 } 755 wpipe->pipe_map.cnt = 0; /* transfer not ready yet */ 756 if (wpipe->pipe_buffer.cnt > 0) { 757 if (wpipe->pipe_state & PIPE_WANTR) { 758 wpipe->pipe_state &= ~PIPE_WANTR; 759 wakeup(wpipe); 760 } 761 762 wpipe->pipe_state |= PIPE_WANTW; 763 error = msleep(wpipe, PIPE_MTX(wpipe), 764 PRIBIO | PCATCH, "pipdwc", 0); 765 if (error) 766 goto error1; 767 if (wpipe->pipe_state & PIPE_EOF) { 768 error = EPIPE; 769 goto error1; 770 } 771 goto retry; 772 } 773 774 wpipe->pipe_state |= PIPE_DIRECTW; 775 776 pipelock(wpipe, 0); 777 PIPE_GET_GIANT(wpipe); 778 error = pipe_build_write_buffer(wpipe, uio); 779 PIPE_DROP_GIANT(wpipe); 780 pipeunlock(wpipe); 781 if (error) { 782 wpipe->pipe_state &= ~PIPE_DIRECTW; 783 goto error1; 784 } 785 786 error = 0; 787 while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) { 788 if (wpipe->pipe_state & PIPE_EOF) { 789 pipelock(wpipe, 0); 790 PIPE_GET_GIANT(wpipe); 791 pipe_destroy_write_buffer(wpipe); 792 PIPE_DROP_GIANT(wpipe); 793 pipeunlock(wpipe); 794 pipeselwakeup(wpipe); 795 error = EPIPE; 796 goto error1; 797 } 798 if (wpipe->pipe_state & PIPE_WANTR) { 799 wpipe->pipe_state &= ~PIPE_WANTR; 800 wakeup(wpipe); 801 } 802 pipeselwakeup(wpipe); 803 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH, 804 "pipdwt", 0); 805 } 806 807 pipelock(wpipe,0); 808 if (wpipe->pipe_state & PIPE_DIRECTW) { 809 /* 810 * this bit of trickery substitutes a kernel buffer for 811 * the process that might be going away. 812 */ 813 pipe_clone_write_buffer(wpipe); 814 } else { 815 PIPE_GET_GIANT(wpipe); 816 pipe_destroy_write_buffer(wpipe); 817 PIPE_DROP_GIANT(wpipe); 818 } 819 pipeunlock(wpipe); 820 return (error); 821 822error1: 823 wakeup(wpipe); 824 return (error); 825} 826#endif 827 828static int 829pipe_write(fp, uio, cred, flags, td) 830 struct file *fp; 831 struct uio *uio; 832 struct ucred *cred; 833 struct thread *td; 834 int flags; 835{ 836 int error = 0; 837 int orig_resid; 838 struct pipe *wpipe, *rpipe; 839 840 rpipe = (struct pipe *) fp->f_data; 841 wpipe = rpipe->pipe_peer; 842 843 PIPE_LOCK(rpipe); 844 /* 845 * detect loss of pipe read side, issue SIGPIPE if lost. 846 */ 847 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { 848 PIPE_UNLOCK(rpipe); 849 return (EPIPE); 850 } 851 ++wpipe->pipe_busy; 852 853 /* 854 * If it is advantageous to resize the pipe buffer, do 855 * so. 856 */ 857 if ((uio->uio_resid > PIPE_SIZE) && 858 (nbigpipe < LIMITBIGPIPES) && 859 (wpipe->pipe_state & PIPE_DIRECTW) == 0 && 860 (wpipe->pipe_buffer.size <= PIPE_SIZE) && 861 (wpipe->pipe_buffer.cnt == 0)) { 862 863 if ((error = pipelock(wpipe,1)) == 0) { 864 PIPE_GET_GIANT(wpipe); 865 if (pipespace(wpipe, BIG_PIPE_SIZE) == 0) 866 nbigpipe++; 867 PIPE_DROP_GIANT(wpipe); 868 pipeunlock(wpipe); 869 } 870 } 871 872 /* 873 * If an early error occured unbusy and return, waking up any pending 874 * readers. 875 */ 876 if (error) { 877 --wpipe->pipe_busy; 878 if ((wpipe->pipe_busy == 0) && 879 (wpipe->pipe_state & PIPE_WANT)) { 880 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 881 wakeup(wpipe); 882 } 883 PIPE_UNLOCK(rpipe); 884 return(error); 885 } 886 887 KASSERT(wpipe->pipe_buffer.buffer != NULL, ("pipe buffer gone")); 888 889 orig_resid = uio->uio_resid; 890 891 while (uio->uio_resid) { 892 int space; 893 894#ifndef PIPE_NODIRECT 895 /* 896 * If the transfer is large, we can gain performance if 897 * we do process-to-process copies directly. 898 * If the write is non-blocking, we don't use the 899 * direct write mechanism. 900 * 901 * The direct write mechanism will detect the reader going 902 * away on us. 903 */ 904 if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT) && 905 (fp->f_flag & FNONBLOCK) == 0 && 906 (wpipe->pipe_map.kva || (amountpipekva < LIMITPIPEKVA)) && 907 (uio->uio_iov->iov_len >= PIPE_MINDIRECT)) { 908 error = pipe_direct_write( wpipe, uio); 909 if (error) 910 break; 911 continue; 912 } 913#endif 914 915 /* 916 * Pipe buffered writes cannot be coincidental with 917 * direct writes. We wait until the currently executing 918 * direct write is completed before we start filling the 919 * pipe buffer. We break out if a signal occurs or the 920 * reader goes away. 921 */ 922 retrywrite: 923 while (wpipe->pipe_state & PIPE_DIRECTW) { 924 if (wpipe->pipe_state & PIPE_WANTR) { 925 wpipe->pipe_state &= ~PIPE_WANTR; 926 wakeup(wpipe); 927 } 928 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH, 929 "pipbww", 0); 930 if (wpipe->pipe_state & PIPE_EOF) 931 break; 932 if (error) 933 break; 934 } 935 if (wpipe->pipe_state & PIPE_EOF) { 936 error = EPIPE; 937 break; 938 } 939 940 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 941 942 /* Writes of size <= PIPE_BUF must be atomic. */ 943 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 944 space = 0; 945 946 if (space > 0 && (wpipe->pipe_buffer.cnt < PIPE_SIZE)) { 947 if ((error = pipelock(wpipe,1)) == 0) { 948 int size; /* Transfer size */ 949 int segsize; /* first segment to transfer */ 950 951 /* 952 * It is possible for a direct write to 953 * slip in on us... handle it here... 954 */ 955 if (wpipe->pipe_state & PIPE_DIRECTW) { 956 pipeunlock(wpipe); 957 goto retrywrite; 958 } 959 /* 960 * If a process blocked in uiomove, our 961 * value for space might be bad. 962 * 963 * XXX will we be ok if the reader has gone 964 * away here? 965 */ 966 if (space > wpipe->pipe_buffer.size - 967 wpipe->pipe_buffer.cnt) { 968 pipeunlock(wpipe); 969 goto retrywrite; 970 } 971 972 /* 973 * Transfer size is minimum of uio transfer 974 * and free space in pipe buffer. 975 */ 976 if (space > uio->uio_resid) 977 size = uio->uio_resid; 978 else 979 size = space; 980 /* 981 * First segment to transfer is minimum of 982 * transfer size and contiguous space in 983 * pipe buffer. If first segment to transfer 984 * is less than the transfer size, we've got 985 * a wraparound in the buffer. 986 */ 987 segsize = wpipe->pipe_buffer.size - 988 wpipe->pipe_buffer.in; 989 if (segsize > size) 990 segsize = size; 991 992 /* Transfer first segment */ 993 994 PIPE_UNLOCK(rpipe); 995 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 996 segsize, uio); 997 PIPE_LOCK(rpipe); 998 999 if (error == 0 && segsize < size) { 1000 /* 1001 * Transfer remaining part now, to 1002 * support atomic writes. Wraparound 1003 * happened. 1004 */ 1005 if (wpipe->pipe_buffer.in + segsize != 1006 wpipe->pipe_buffer.size) 1007 panic("Expected pipe buffer wraparound disappeared"); 1008 1009 PIPE_UNLOCK(rpipe); 1010 error = uiomove(&wpipe->pipe_buffer.buffer[0], 1011 size - segsize, uio); 1012 PIPE_LOCK(rpipe); 1013 } 1014 if (error == 0) { 1015 wpipe->pipe_buffer.in += size; 1016 if (wpipe->pipe_buffer.in >= 1017 wpipe->pipe_buffer.size) { 1018 if (wpipe->pipe_buffer.in != size - segsize + wpipe->pipe_buffer.size) 1019 panic("Expected wraparound bad"); 1020 wpipe->pipe_buffer.in = size - segsize; 1021 } 1022 1023 wpipe->pipe_buffer.cnt += size; 1024 if (wpipe->pipe_buffer.cnt > wpipe->pipe_buffer.size) 1025 panic("Pipe buffer overflow"); 1026 1027 } 1028 pipeunlock(wpipe); 1029 } 1030 if (error) 1031 break; 1032 1033 } else { 1034 /* 1035 * If the "read-side" has been blocked, wake it up now. 1036 */ 1037 if (wpipe->pipe_state & PIPE_WANTR) { 1038 wpipe->pipe_state &= ~PIPE_WANTR; 1039 wakeup(wpipe); 1040 } 1041 1042 /* 1043 * don't block on non-blocking I/O 1044 */ 1045 if (fp->f_flag & FNONBLOCK) { 1046 error = EAGAIN; 1047 break; 1048 } 1049 1050 /* 1051 * We have no more space and have something to offer, 1052 * wake up select/poll. 1053 */ 1054 pipeselwakeup(wpipe); 1055 1056 wpipe->pipe_state |= PIPE_WANTW; 1057 error = msleep(wpipe, PIPE_MTX(rpipe), 1058 PRIBIO | PCATCH, "pipewr", 0); 1059 if (error != 0) 1060 break; 1061 /* 1062 * If read side wants to go away, we just issue a signal 1063 * to ourselves. 1064 */ 1065 if (wpipe->pipe_state & PIPE_EOF) { 1066 error = EPIPE; 1067 break; 1068 } 1069 } 1070 } 1071 1072 --wpipe->pipe_busy; 1073 1074 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 1075 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 1076 wakeup(wpipe); 1077 } else if (wpipe->pipe_buffer.cnt > 0) { 1078 /* 1079 * If we have put any characters in the buffer, we wake up 1080 * the reader. 1081 */ 1082 if (wpipe->pipe_state & PIPE_WANTR) { 1083 wpipe->pipe_state &= ~PIPE_WANTR; 1084 wakeup(wpipe); 1085 } 1086 } 1087 1088 /* 1089 * Don't return EPIPE if I/O was successful 1090 */ 1091 if ((wpipe->pipe_buffer.cnt == 0) && 1092 (uio->uio_resid == 0) && 1093 (error == EPIPE)) { 1094 error = 0; 1095 } 1096 1097 if (error == 0) 1098 vfs_timestamp(&wpipe->pipe_mtime); 1099 1100 /* 1101 * We have something to offer, 1102 * wake up select/poll. 1103 */ 1104 if (wpipe->pipe_buffer.cnt) 1105 pipeselwakeup(wpipe); 1106 1107 PIPE_UNLOCK(rpipe); 1108 return (error); 1109} 1110 1111/* 1112 * we implement a very minimal set of ioctls for compatibility with sockets. 1113 */ 1114int 1115pipe_ioctl(fp, cmd, data, td) 1116 struct file *fp; 1117 u_long cmd; 1118 caddr_t data; 1119 struct thread *td; 1120{ 1121 struct pipe *mpipe = (struct pipe *)fp->f_data; 1122 1123 switch (cmd) { 1124 1125 case FIONBIO: 1126 return (0); 1127 1128 case FIOASYNC: 1129 PIPE_LOCK(mpipe); 1130 if (*(int *)data) { 1131 mpipe->pipe_state |= PIPE_ASYNC; 1132 } else { 1133 mpipe->pipe_state &= ~PIPE_ASYNC; 1134 } 1135 PIPE_UNLOCK(mpipe); 1136 return (0); 1137 1138 case FIONREAD: 1139 PIPE_LOCK(mpipe); 1140 if (mpipe->pipe_state & PIPE_DIRECTW) 1141 *(int *)data = mpipe->pipe_map.cnt; 1142 else 1143 *(int *)data = mpipe->pipe_buffer.cnt; 1144 PIPE_UNLOCK(mpipe); 1145 return (0); 1146 1147 case FIOSETOWN: 1148 return (fsetown(*(int *)data, &mpipe->pipe_sigio)); 1149 1150 case FIOGETOWN: 1151 *(int *)data = fgetown(mpipe->pipe_sigio); 1152 return (0); 1153 1154 /* This is deprecated, FIOSETOWN should be used instead. */ 1155 case TIOCSPGRP: 1156 return (fsetown(-(*(int *)data), &mpipe->pipe_sigio)); 1157 1158 /* This is deprecated, FIOGETOWN should be used instead. */ 1159 case TIOCGPGRP: 1160 *(int *)data = -fgetown(mpipe->pipe_sigio); 1161 return (0); 1162 1163 } 1164 return (ENOTTY); 1165} 1166 1167int 1168pipe_poll(fp, events, cred, td) 1169 struct file *fp; 1170 int events; 1171 struct ucred *cred; 1172 struct thread *td; 1173{ 1174 struct pipe *rpipe = (struct pipe *)fp->f_data; 1175 struct pipe *wpipe; 1176 int revents = 0; 1177 1178 wpipe = rpipe->pipe_peer; 1179 PIPE_LOCK(rpipe); 1180 if (events & (POLLIN | POLLRDNORM)) 1181 if ((rpipe->pipe_state & PIPE_DIRECTW) || 1182 (rpipe->pipe_buffer.cnt > 0) || 1183 (rpipe->pipe_state & PIPE_EOF)) 1184 revents |= events & (POLLIN | POLLRDNORM); 1185 1186 if (events & (POLLOUT | POLLWRNORM)) 1187 if (wpipe == NULL || (wpipe->pipe_state & PIPE_EOF) || 1188 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) && 1189 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF)) 1190 revents |= events & (POLLOUT | POLLWRNORM); 1191 1192 if ((rpipe->pipe_state & PIPE_EOF) || 1193 (wpipe == NULL) || 1194 (wpipe->pipe_state & PIPE_EOF)) 1195 revents |= POLLHUP; 1196 1197 if (revents == 0) { 1198 if (events & (POLLIN | POLLRDNORM)) { 1199 selrecord(td, &rpipe->pipe_sel); 1200 rpipe->pipe_state |= PIPE_SEL; 1201 } 1202 1203 if (events & (POLLOUT | POLLWRNORM)) { 1204 selrecord(td, &wpipe->pipe_sel); 1205 wpipe->pipe_state |= PIPE_SEL; 1206 } 1207 } 1208 PIPE_UNLOCK(rpipe); 1209 1210 return (revents); 1211} 1212 1213static int 1214pipe_stat(fp, ub, td) 1215 struct file *fp; 1216 struct stat *ub; 1217 struct thread *td; 1218{ 1219 struct pipe *pipe = (struct pipe *)fp->f_data; 1220 1221 bzero((caddr_t)ub, sizeof(*ub)); 1222 ub->st_mode = S_IFIFO; 1223 ub->st_blksize = pipe->pipe_buffer.size; 1224 ub->st_size = pipe->pipe_buffer.cnt; 1225 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize; 1226 ub->st_atimespec = pipe->pipe_atime; 1227 ub->st_mtimespec = pipe->pipe_mtime; 1228 ub->st_ctimespec = pipe->pipe_ctime; 1229 ub->st_uid = fp->f_cred->cr_uid; 1230 ub->st_gid = fp->f_cred->cr_gid; 1231 /* 1232 * Left as 0: st_dev, st_ino, st_nlink, st_rdev, st_flags, st_gen. 1233 * XXX (st_dev, st_ino) should be unique. 1234 */ 1235 return (0); 1236} 1237 1238/* ARGSUSED */ 1239static int 1240pipe_close(fp, td) 1241 struct file *fp; 1242 struct thread *td; 1243{ 1244 struct pipe *cpipe = (struct pipe *)fp->f_data; 1245 1246 fp->f_ops = &badfileops; 1247 fp->f_data = NULL; 1248 funsetown(cpipe->pipe_sigio); 1249 pipeclose(cpipe); 1250 return (0); 1251} 1252 1253static void 1254pipe_free_kmem(cpipe) 1255 struct pipe *cpipe; 1256{ 1257 1258 GIANT_REQUIRED; 1259 KASSERT(cpipe->pipe_mtxp == NULL || !mtx_owned(PIPE_MTX(cpipe)), 1260 ("pipespace: pipe mutex locked")); 1261 1262 if (cpipe->pipe_buffer.buffer != NULL) { 1263 if (cpipe->pipe_buffer.size > PIPE_SIZE) 1264 --nbigpipe; 1265 amountpipekva -= cpipe->pipe_buffer.size; 1266 kmem_free(kernel_map, 1267 (vm_offset_t)cpipe->pipe_buffer.buffer, 1268 cpipe->pipe_buffer.size); 1269 cpipe->pipe_buffer.buffer = NULL; 1270 } 1271#ifndef PIPE_NODIRECT 1272 if (cpipe->pipe_map.kva != NULL) { 1273 amountpipekva -= cpipe->pipe_buffer.size + PAGE_SIZE; 1274 kmem_free(kernel_map, 1275 cpipe->pipe_map.kva, 1276 cpipe->pipe_buffer.size + PAGE_SIZE); 1277 cpipe->pipe_map.cnt = 0; 1278 cpipe->pipe_map.kva = 0; 1279 cpipe->pipe_map.pos = 0; 1280 cpipe->pipe_map.npages = 0; 1281 } 1282#endif 1283} 1284 1285/* 1286 * shutdown the pipe 1287 */ 1288static void 1289pipeclose(cpipe) 1290 struct pipe *cpipe; 1291{ 1292 struct pipe *ppipe; 1293 int hadpeer; 1294 1295 if (cpipe == NULL) 1296 return; 1297 1298 hadpeer = 0; 1299 1300 /* partially created pipes won't have a valid mutex. */ 1301 if (PIPE_MTX(cpipe) != NULL) 1302 PIPE_LOCK(cpipe); 1303 1304 pipeselwakeup(cpipe); 1305 1306 /* 1307 * If the other side is blocked, wake it up saying that 1308 * we want to close it down. 1309 */ 1310 while (cpipe->pipe_busy) { 1311 wakeup(cpipe); 1312 cpipe->pipe_state |= PIPE_WANT | PIPE_EOF; 1313 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0); 1314 } 1315 1316 /* 1317 * Disconnect from peer 1318 */ 1319 if ((ppipe = cpipe->pipe_peer) != NULL) { 1320 hadpeer++; 1321 pipeselwakeup(ppipe); 1322 1323 ppipe->pipe_state |= PIPE_EOF; 1324 wakeup(ppipe); 1325 KNOTE(&ppipe->pipe_sel.si_note, 0); 1326 ppipe->pipe_peer = NULL; 1327 } 1328 /* 1329 * free resources 1330 */ 1331 if (PIPE_MTX(cpipe) != NULL) { 1332 PIPE_UNLOCK(cpipe); 1333 if (!hadpeer) { 1334 mtx_destroy(PIPE_MTX(cpipe)); 1335 free(PIPE_MTX(cpipe), M_TEMP); 1336 } 1337 } 1338 mtx_lock(&Giant); 1339 pipe_free_kmem(cpipe); 1340 zfree(pipe_zone, cpipe); 1341 mtx_unlock(&Giant); 1342} 1343 1344/*ARGSUSED*/ 1345static int 1346pipe_kqfilter(struct file *fp, struct knote *kn) 1347{ 1348 struct pipe *cpipe; 1349 1350 cpipe = (struct pipe *)kn->kn_fp->f_data; 1351 switch (kn->kn_filter) { 1352 case EVFILT_READ: 1353 kn->kn_fop = &pipe_rfiltops; 1354 break; 1355 case EVFILT_WRITE: 1356 kn->kn_fop = &pipe_wfiltops; 1357 cpipe = cpipe->pipe_peer; 1358 break; 1359 default: 1360 return (1); 1361 } 1362 kn->kn_hook = (caddr_t)cpipe; 1363 1364 PIPE_LOCK(cpipe); 1365 SLIST_INSERT_HEAD(&cpipe->pipe_sel.si_note, kn, kn_selnext); 1366 PIPE_UNLOCK(cpipe); 1367 return (0); 1368} 1369 1370static void 1371filt_pipedetach(struct knote *kn) 1372{ 1373 struct pipe *cpipe = (struct pipe *)kn->kn_hook; 1374 1375 PIPE_LOCK(cpipe); 1376 SLIST_REMOVE(&cpipe->pipe_sel.si_note, kn, knote, kn_selnext); 1377 PIPE_UNLOCK(cpipe); 1378} 1379 1380/*ARGSUSED*/ 1381static int 1382filt_piperead(struct knote *kn, long hint) 1383{ 1384 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; 1385 struct pipe *wpipe = rpipe->pipe_peer; 1386 1387 PIPE_LOCK(rpipe); 1388 kn->kn_data = rpipe->pipe_buffer.cnt; 1389 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) 1390 kn->kn_data = rpipe->pipe_map.cnt; 1391 1392 if ((rpipe->pipe_state & PIPE_EOF) || 1393 (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { 1394 kn->kn_flags |= EV_EOF; 1395 PIPE_UNLOCK(rpipe); 1396 return (1); 1397 } 1398 PIPE_UNLOCK(rpipe); 1399 return (kn->kn_data > 0); 1400} 1401 1402/*ARGSUSED*/ 1403static int 1404filt_pipewrite(struct knote *kn, long hint) 1405{ 1406 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; 1407 struct pipe *wpipe = rpipe->pipe_peer; 1408 1409 PIPE_LOCK(rpipe); 1410 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { 1411 kn->kn_data = 0; 1412 kn->kn_flags |= EV_EOF; 1413 PIPE_UNLOCK(rpipe); 1414 return (1); 1415 } 1416 kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1417 if (wpipe->pipe_state & PIPE_DIRECTW) 1418 kn->kn_data = 0; 1419 1420 PIPE_UNLOCK(rpipe); 1421 return (kn->kn_data >= PIPE_BUF); 1422}
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