Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/sys_pipe.c
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1 /* 2 * Copyright (c) 1996 John S. Dyson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice immediately at the beginning of the file, without modification, 10 * this list of conditions, and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Absolutely no warranty of function or purpose is made by the author 15 * John S. Dyson. 16 * 4. Modifications may be freely made to this file if the above conditions 17 * are met. 18 * 19 * $FreeBSD: releng/5.0/sys/kern/sys_pipe.c 105132 2002-10-14 21:15:04Z alfred $ 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 "opt_mac.h" 53 54 #include <sys/param.h> 55 #include <sys/systm.h> 56 #include <sys/fcntl.h> 57 #include <sys/file.h> 58 #include <sys/filedesc.h> 59 #include <sys/filio.h> 60 #include <sys/kernel.h> 61 #include <sys/lock.h> 62 #include <sys/mac.h> 63 #include <sys/mutex.h> 64 #include <sys/ttycom.h> 65 #include <sys/stat.h> 66 #include <sys/malloc.h> 67 #include <sys/poll.h> 68 #include <sys/selinfo.h> 69 #include <sys/signalvar.h> 70 #include <sys/sysproto.h> 71 #include <sys/pipe.h> 72 #include <sys/proc.h> 73 #include <sys/vnode.h> 74 #include <sys/uio.h> 75 #include <sys/event.h> 76 77 #include <vm/vm.h> 78 #include <vm/vm_param.h> 79 #include <vm/vm_object.h> 80 #include <vm/vm_kern.h> 81 #include <vm/vm_extern.h> 82 #include <vm/pmap.h> 83 #include <vm/vm_map.h> 84 #include <vm/vm_page.h> 85 #include <vm/uma.h> 86 87 /* 88 * Use this define if you want to disable *fancy* VM things. Expect an 89 * approx 30% decrease in transfer rate. This could be useful for 90 * NetBSD or OpenBSD. 91 */ 92 /* #define PIPE_NODIRECT */ 93 94 /* 95 * interfaces to the outside world 96 */ 97 static int pipe_read(struct file *fp, struct uio *uio, 98 struct ucred *active_cred, int flags, struct thread *td); 99 static int pipe_write(struct file *fp, struct uio *uio, 100 struct ucred *active_cred, int flags, struct thread *td); 101 static int pipe_close(struct file *fp, struct thread *td); 102 static int pipe_poll(struct file *fp, int events, struct ucred *active_cred, 103 struct thread *td); 104 static int pipe_kqfilter(struct file *fp, struct knote *kn); 105 static int pipe_stat(struct file *fp, struct stat *sb, 106 struct ucred *active_cred, struct thread *td); 107 static int pipe_ioctl(struct file *fp, u_long cmd, void *data, 108 struct ucred *active_cred, struct thread *td); 109 110 static struct fileops pipeops = { 111 pipe_read, pipe_write, pipe_ioctl, pipe_poll, pipe_kqfilter, 112 pipe_stat, pipe_close 113 }; 114 115 static void filt_pipedetach(struct knote *kn); 116 static int filt_piperead(struct knote *kn, long hint); 117 static int filt_pipewrite(struct knote *kn, long hint); 118 119 static struct filterops pipe_rfiltops = 120 { 1, NULL, filt_pipedetach, filt_piperead }; 121 static struct filterops pipe_wfiltops = 122 { 1, NULL, filt_pipedetach, filt_pipewrite }; 123 124 #define PIPE_GET_GIANT(pipe) \ 125 do { \ 126 KASSERT(((pipe)->pipe_state & PIPE_LOCKFL) != 0, \ 127 ("%s:%d PIPE_GET_GIANT: line pipe not locked", \ 128 __FILE__, __LINE__)); \ 129 PIPE_UNLOCK(pipe); \ 130 mtx_lock(&Giant); \ 131 } while (0) 132 133 #define PIPE_DROP_GIANT(pipe) \ 134 do { \ 135 mtx_unlock(&Giant); \ 136 PIPE_LOCK(pipe); \ 137 } while (0) 138 139 /* 140 * Default pipe buffer size(s), this can be kind-of large now because pipe 141 * space is pageable. The pipe code will try to maintain locality of 142 * reference for performance reasons, so small amounts of outstanding I/O 143 * will not wipe the cache. 144 */ 145 #define MINPIPESIZE (PIPE_SIZE/3) 146 #define MAXPIPESIZE (2*PIPE_SIZE/3) 147 148 /* 149 * Maximum amount of kva for pipes -- this is kind-of a soft limit, but 150 * is there so that on large systems, we don't exhaust it. 151 */ 152 #define MAXPIPEKVA (8*1024*1024) 153 154 /* 155 * Limit for direct transfers, we cannot, of course limit 156 * the amount of kva for pipes in general though. 157 */ 158 #define LIMITPIPEKVA (16*1024*1024) 159 160 /* 161 * Limit the number of "big" pipes 162 */ 163 #define LIMITBIGPIPES 32 164 static int nbigpipe; 165 166 static int amountpipekva; 167 168 static void pipeinit(void *dummy __unused); 169 static void pipeclose(struct pipe *cpipe); 170 static void pipe_free_kmem(struct pipe *cpipe); 171 static int pipe_create(struct pipe **cpipep); 172 static __inline int pipelock(struct pipe *cpipe, int catch); 173 static __inline void pipeunlock(struct pipe *cpipe); 174 static __inline void pipeselwakeup(struct pipe *cpipe); 175 #ifndef PIPE_NODIRECT 176 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio); 177 static void pipe_destroy_write_buffer(struct pipe *wpipe); 178 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio); 179 static void pipe_clone_write_buffer(struct pipe *wpipe); 180 #endif 181 static int pipespace(struct pipe *cpipe, int size); 182 183 static uma_zone_t pipe_zone; 184 185 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL); 186 187 static void 188 pipeinit(void *dummy __unused) 189 { 190 pipe_zone = uma_zcreate("PIPE", sizeof(struct pipe), NULL, 191 NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 192 } 193 194 /* 195 * The pipe system call for the DTYPE_PIPE type of pipes 196 */ 197 198 /* ARGSUSED */ 199 int 200 pipe(td, uap) 201 struct thread *td; 202 struct pipe_args /* { 203 int dummy; 204 } */ *uap; 205 { 206 struct filedesc *fdp = td->td_proc->p_fd; 207 struct file *rf, *wf; 208 struct pipe *rpipe, *wpipe; 209 struct mtx *pmtx; 210 int fd, error; 211 212 KASSERT(pipe_zone != NULL, ("pipe_zone not initialized")); 213 214 pmtx = malloc(sizeof(*pmtx), M_TEMP, M_WAITOK | M_ZERO); 215 216 rpipe = wpipe = NULL; 217 if (pipe_create(&rpipe) || pipe_create(&wpipe)) { 218 pipeclose(rpipe); 219 pipeclose(wpipe); 220 free(pmtx, M_TEMP); 221 return (ENFILE); 222 } 223 224 rpipe->pipe_state |= PIPE_DIRECTOK; 225 wpipe->pipe_state |= PIPE_DIRECTOK; 226 227 error = falloc(td, &rf, &fd); 228 if (error) { 229 pipeclose(rpipe); 230 pipeclose(wpipe); 231 free(pmtx, M_TEMP); 232 return (error); 233 } 234 fhold(rf); 235 td->td_retval[0] = fd; 236 237 /* 238 * Warning: once we've gotten past allocation of the fd for the 239 * read-side, we can only drop the read side via fdrop() in order 240 * to avoid races against processes which manage to dup() the read 241 * side while we are blocked trying to allocate the write side. 242 */ 243 FILE_LOCK(rf); 244 rf->f_flag = FREAD | FWRITE; 245 rf->f_type = DTYPE_PIPE; 246 rf->f_data = rpipe; 247 rf->f_ops = &pipeops; 248 FILE_UNLOCK(rf); 249 error = falloc(td, &wf, &fd); 250 if (error) { 251 FILEDESC_LOCK(fdp); 252 if (fdp->fd_ofiles[td->td_retval[0]] == rf) { 253 fdp->fd_ofiles[td->td_retval[0]] = NULL; 254 FILEDESC_UNLOCK(fdp); 255 fdrop(rf, td); 256 } else 257 FILEDESC_UNLOCK(fdp); 258 fdrop(rf, td); 259 /* rpipe has been closed by fdrop(). */ 260 pipeclose(wpipe); 261 free(pmtx, M_TEMP); 262 return (error); 263 } 264 FILE_LOCK(wf); 265 wf->f_flag = FREAD | FWRITE; 266 wf->f_type = DTYPE_PIPE; 267 wf->f_data = wpipe; 268 wf->f_ops = &pipeops; 269 FILE_UNLOCK(wf); 270 td->td_retval[1] = fd; 271 rpipe->pipe_peer = wpipe; 272 wpipe->pipe_peer = rpipe; 273 #ifdef MAC 274 /* 275 * struct pipe represents a pipe endpoint. The MAC label is shared 276 * between the connected endpoints. As a result mac_init_pipe() and 277 * mac_create_pipe() should only be called on one of the endpoints 278 * after they have been connected. 279 */ 280 mac_init_pipe(rpipe); 281 mac_create_pipe(td->td_ucred, rpipe); 282 #endif 283 mtx_init(pmtx, "pipe mutex", NULL, MTX_DEF | MTX_RECURSE); 284 rpipe->pipe_mtxp = wpipe->pipe_mtxp = pmtx; 285 fdrop(rf, td); 286 287 return (0); 288 } 289 290 /* 291 * Allocate kva for pipe circular buffer, the space is pageable 292 * This routine will 'realloc' the size of a pipe safely, if it fails 293 * it will retain the old buffer. 294 * If it fails it will return ENOMEM. 295 */ 296 static int 297 pipespace(cpipe, size) 298 struct pipe *cpipe; 299 int size; 300 { 301 struct vm_object *object; 302 caddr_t buffer; 303 int npages, error; 304 305 GIANT_REQUIRED; 306 KASSERT(cpipe->pipe_mtxp == NULL || !mtx_owned(PIPE_MTX(cpipe)), 307 ("pipespace: pipe mutex locked")); 308 309 npages = round_page(size)/PAGE_SIZE; 310 /* 311 * Create an object, I don't like the idea of paging to/from 312 * kernel_object. 313 * XXX -- minor change needed here for NetBSD/OpenBSD VM systems. 314 */ 315 object = vm_object_allocate(OBJT_DEFAULT, npages); 316 buffer = (caddr_t) vm_map_min(kernel_map); 317 318 /* 319 * Insert the object into the kernel map, and allocate kva for it. 320 * The map entry is, by default, pageable. 321 * XXX -- minor change needed here for NetBSD/OpenBSD VM systems. 322 */ 323 error = vm_map_find(kernel_map, object, 0, 324 (vm_offset_t *) &buffer, size, 1, 325 VM_PROT_ALL, VM_PROT_ALL, 0); 326 327 if (error != KERN_SUCCESS) { 328 vm_object_deallocate(object); 329 return (ENOMEM); 330 } 331 332 /* free old resources if we're resizing */ 333 pipe_free_kmem(cpipe); 334 cpipe->pipe_buffer.object = object; 335 cpipe->pipe_buffer.buffer = buffer; 336 cpipe->pipe_buffer.size = size; 337 cpipe->pipe_buffer.in = 0; 338 cpipe->pipe_buffer.out = 0; 339 cpipe->pipe_buffer.cnt = 0; 340 amountpipekva += cpipe->pipe_buffer.size; 341 return (0); 342 } 343 344 /* 345 * initialize and allocate VM and memory for pipe 346 */ 347 static int 348 pipe_create(cpipep) 349 struct pipe **cpipep; 350 { 351 struct pipe *cpipe; 352 int error; 353 354 *cpipep = uma_zalloc(pipe_zone, M_WAITOK); 355 if (*cpipep == NULL) 356 return (ENOMEM); 357 358 cpipe = *cpipep; 359 360 /* so pipespace()->pipe_free_kmem() doesn't follow junk pointer */ 361 cpipe->pipe_buffer.object = NULL; 362 #ifndef PIPE_NODIRECT 363 cpipe->pipe_map.kva = 0; 364 #endif 365 /* 366 * protect so pipeclose() doesn't follow a junk pointer 367 * if pipespace() fails. 368 */ 369 bzero(&cpipe->pipe_sel, sizeof(cpipe->pipe_sel)); 370 cpipe->pipe_state = 0; 371 cpipe->pipe_peer = NULL; 372 cpipe->pipe_busy = 0; 373 374 #ifndef PIPE_NODIRECT 375 /* 376 * pipe data structure initializations to support direct pipe I/O 377 */ 378 cpipe->pipe_map.cnt = 0; 379 cpipe->pipe_map.kva = 0; 380 cpipe->pipe_map.pos = 0; 381 cpipe->pipe_map.npages = 0; 382 /* cpipe->pipe_map.ms[] = invalid */ 383 #endif 384 385 cpipe->pipe_mtxp = NULL; /* avoid pipespace assertion */ 386 error = pipespace(cpipe, PIPE_SIZE); 387 if (error) 388 return (error); 389 390 vfs_timestamp(&cpipe->pipe_ctime); 391 cpipe->pipe_atime = cpipe->pipe_ctime; 392 cpipe->pipe_mtime = cpipe->pipe_ctime; 393 394 return (0); 395 } 396 397 398 /* 399 * lock a pipe for I/O, blocking other access 400 */ 401 static __inline int 402 pipelock(cpipe, catch) 403 struct pipe *cpipe; 404 int catch; 405 { 406 int error; 407 408 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 409 while (cpipe->pipe_state & PIPE_LOCKFL) { 410 cpipe->pipe_state |= PIPE_LWANT; 411 error = msleep(cpipe, PIPE_MTX(cpipe), 412 catch ? (PRIBIO | PCATCH) : PRIBIO, 413 "pipelk", 0); 414 if (error != 0) 415 return (error); 416 } 417 cpipe->pipe_state |= PIPE_LOCKFL; 418 return (0); 419 } 420 421 /* 422 * unlock a pipe I/O lock 423 */ 424 static __inline void 425 pipeunlock(cpipe) 426 struct pipe *cpipe; 427 { 428 429 PIPE_LOCK_ASSERT(cpipe, MA_OWNED); 430 cpipe->pipe_state &= ~PIPE_LOCKFL; 431 if (cpipe->pipe_state & PIPE_LWANT) { 432 cpipe->pipe_state &= ~PIPE_LWANT; 433 wakeup(cpipe); 434 } 435 } 436 437 static __inline void 438 pipeselwakeup(cpipe) 439 struct pipe *cpipe; 440 { 441 442 if (cpipe->pipe_state & PIPE_SEL) { 443 cpipe->pipe_state &= ~PIPE_SEL; 444 selwakeup(&cpipe->pipe_sel); 445 } 446 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) 447 pgsigio(&cpipe->pipe_sigio, SIGIO, 0); 448 KNOTE(&cpipe->pipe_sel.si_note, 0); 449 } 450 451 /* ARGSUSED */ 452 static int 453 pipe_read(fp, uio, active_cred, flags, td) 454 struct file *fp; 455 struct uio *uio; 456 struct ucred *active_cred; 457 struct thread *td; 458 int flags; 459 { 460 struct pipe *rpipe = (struct pipe *) fp->f_data; 461 int error; 462 int nread = 0; 463 u_int size; 464 465 PIPE_LOCK(rpipe); 466 ++rpipe->pipe_busy; 467 error = pipelock(rpipe, 1); 468 if (error) 469 goto unlocked_error; 470 471 #ifdef MAC 472 error = mac_check_pipe_read(active_cred, rpipe); 473 if (error) 474 goto locked_error; 475 #endif 476 477 while (uio->uio_resid) { 478 /* 479 * normal pipe buffer receive 480 */ 481 if (rpipe->pipe_buffer.cnt > 0) { 482 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 483 if (size > rpipe->pipe_buffer.cnt) 484 size = rpipe->pipe_buffer.cnt; 485 if (size > (u_int) uio->uio_resid) 486 size = (u_int) uio->uio_resid; 487 488 PIPE_UNLOCK(rpipe); 489 error = uiomove(&rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 490 size, uio); 491 PIPE_LOCK(rpipe); 492 if (error) 493 break; 494 495 rpipe->pipe_buffer.out += size; 496 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 497 rpipe->pipe_buffer.out = 0; 498 499 rpipe->pipe_buffer.cnt -= size; 500 501 /* 502 * If there is no more to read in the pipe, reset 503 * its pointers to the beginning. This improves 504 * cache hit stats. 505 */ 506 if (rpipe->pipe_buffer.cnt == 0) { 507 rpipe->pipe_buffer.in = 0; 508 rpipe->pipe_buffer.out = 0; 509 } 510 nread += size; 511 #ifndef PIPE_NODIRECT 512 /* 513 * Direct copy, bypassing a kernel buffer. 514 */ 515 } else if ((size = rpipe->pipe_map.cnt) && 516 (rpipe->pipe_state & PIPE_DIRECTW)) { 517 caddr_t va; 518 if (size > (u_int) uio->uio_resid) 519 size = (u_int) uio->uio_resid; 520 521 va = (caddr_t) rpipe->pipe_map.kva + 522 rpipe->pipe_map.pos; 523 PIPE_UNLOCK(rpipe); 524 error = uiomove(va, size, uio); 525 PIPE_LOCK(rpipe); 526 if (error) 527 break; 528 nread += size; 529 rpipe->pipe_map.pos += size; 530 rpipe->pipe_map.cnt -= size; 531 if (rpipe->pipe_map.cnt == 0) { 532 rpipe->pipe_state &= ~PIPE_DIRECTW; 533 wakeup(rpipe); 534 } 535 #endif 536 } else { 537 /* 538 * detect EOF condition 539 * read returns 0 on EOF, no need to set error 540 */ 541 if (rpipe->pipe_state & PIPE_EOF) 542 break; 543 544 /* 545 * If the "write-side" has been blocked, wake it up now. 546 */ 547 if (rpipe->pipe_state & PIPE_WANTW) { 548 rpipe->pipe_state &= ~PIPE_WANTW; 549 wakeup(rpipe); 550 } 551 552 /* 553 * Break if some data was read. 554 */ 555 if (nread > 0) 556 break; 557 558 /* 559 * Unlock the pipe buffer for our remaining processing. We 560 * will either break out with an error or we will sleep and 561 * relock to loop. 562 */ 563 pipeunlock(rpipe); 564 565 /* 566 * Handle non-blocking mode operation or 567 * wait for more data. 568 */ 569 if (fp->f_flag & FNONBLOCK) { 570 error = EAGAIN; 571 } else { 572 rpipe->pipe_state |= PIPE_WANTR; 573 if ((error = msleep(rpipe, PIPE_MTX(rpipe), 574 PRIBIO | PCATCH, 575 "piperd", 0)) == 0) 576 error = pipelock(rpipe, 1); 577 } 578 if (error) 579 goto unlocked_error; 580 } 581 } 582 #ifdef MAC 583 locked_error: 584 #endif 585 pipeunlock(rpipe); 586 587 /* XXX: should probably do this before getting any locks. */ 588 if (error == 0) 589 vfs_timestamp(&rpipe->pipe_atime); 590 unlocked_error: 591 --rpipe->pipe_busy; 592 593 /* 594 * PIPE_WANT processing only makes sense if pipe_busy is 0. 595 */ 596 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 597 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 598 wakeup(rpipe); 599 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 600 /* 601 * Handle write blocking hysteresis. 602 */ 603 if (rpipe->pipe_state & PIPE_WANTW) { 604 rpipe->pipe_state &= ~PIPE_WANTW; 605 wakeup(rpipe); 606 } 607 } 608 609 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF) 610 pipeselwakeup(rpipe); 611 612 PIPE_UNLOCK(rpipe); 613 return (error); 614 } 615 616 #ifndef PIPE_NODIRECT 617 /* 618 * Map the sending processes' buffer into kernel space and wire it. 619 * This is similar to a physical write operation. 620 */ 621 static int 622 pipe_build_write_buffer(wpipe, uio) 623 struct pipe *wpipe; 624 struct uio *uio; 625 { 626 u_int size; 627 int i; 628 vm_offset_t addr, endaddr, paddr; 629 630 GIANT_REQUIRED; 631 PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED); 632 633 size = (u_int) uio->uio_iov->iov_len; 634 if (size > wpipe->pipe_buffer.size) 635 size = wpipe->pipe_buffer.size; 636 637 endaddr = round_page((vm_offset_t)uio->uio_iov->iov_base + size); 638 addr = trunc_page((vm_offset_t)uio->uio_iov->iov_base); 639 for (i = 0; addr < endaddr; addr += PAGE_SIZE, i++) { 640 vm_page_t m; 641 642 /* 643 * vm_fault_quick() can sleep. Consequently, 644 * vm_page_lock_queue() and vm_page_unlock_queue() 645 * should not be performed outside of this loop. 646 */ 647 if (vm_fault_quick((caddr_t)addr, VM_PROT_READ) < 0 || 648 (paddr = pmap_extract(vmspace_pmap(curproc->p_vmspace), 649 addr)) == 0) { 650 int j; 651 652 vm_page_lock_queues(); 653 for (j = 0; j < i; j++) 654 vm_page_unwire(wpipe->pipe_map.ms[j], 1); 655 vm_page_unlock_queues(); 656 return (EFAULT); 657 } 658 659 m = PHYS_TO_VM_PAGE(paddr); 660 vm_page_lock_queues(); 661 vm_page_wire(m); 662 vm_page_unlock_queues(); 663 wpipe->pipe_map.ms[i] = m; 664 } 665 666 /* 667 * set up the control block 668 */ 669 wpipe->pipe_map.npages = i; 670 wpipe->pipe_map.pos = 671 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 672 wpipe->pipe_map.cnt = size; 673 674 /* 675 * and map the buffer 676 */ 677 if (wpipe->pipe_map.kva == 0) { 678 /* 679 * We need to allocate space for an extra page because the 680 * address range might (will) span pages at times. 681 */ 682 wpipe->pipe_map.kva = kmem_alloc_pageable(kernel_map, 683 wpipe->pipe_buffer.size + PAGE_SIZE); 684 amountpipekva += wpipe->pipe_buffer.size + PAGE_SIZE; 685 } 686 pmap_qenter(wpipe->pipe_map.kva, wpipe->pipe_map.ms, 687 wpipe->pipe_map.npages); 688 689 /* 690 * and update the uio data 691 */ 692 693 uio->uio_iov->iov_len -= size; 694 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size; 695 if (uio->uio_iov->iov_len == 0) 696 uio->uio_iov++; 697 uio->uio_resid -= size; 698 uio->uio_offset += size; 699 return (0); 700 } 701 702 /* 703 * unmap and unwire the process buffer 704 */ 705 static void 706 pipe_destroy_write_buffer(wpipe) 707 struct pipe *wpipe; 708 { 709 int i; 710 711 GIANT_REQUIRED; 712 PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED); 713 714 if (wpipe->pipe_map.kva) { 715 pmap_qremove(wpipe->pipe_map.kva, wpipe->pipe_map.npages); 716 717 if (amountpipekva > MAXPIPEKVA) { 718 vm_offset_t kva = wpipe->pipe_map.kva; 719 wpipe->pipe_map.kva = 0; 720 kmem_free(kernel_map, kva, 721 wpipe->pipe_buffer.size + PAGE_SIZE); 722 amountpipekva -= wpipe->pipe_buffer.size + PAGE_SIZE; 723 } 724 } 725 vm_page_lock_queues(); 726 for (i = 0; i < wpipe->pipe_map.npages; i++) 727 vm_page_unwire(wpipe->pipe_map.ms[i], 1); 728 vm_page_unlock_queues(); 729 wpipe->pipe_map.npages = 0; 730 } 731 732 /* 733 * In the case of a signal, the writing process might go away. This 734 * code copies the data into the circular buffer so that the source 735 * pages can be freed without loss of data. 736 */ 737 static void 738 pipe_clone_write_buffer(wpipe) 739 struct pipe *wpipe; 740 { 741 int size; 742 int pos; 743 744 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 745 size = wpipe->pipe_map.cnt; 746 pos = wpipe->pipe_map.pos; 747 748 wpipe->pipe_buffer.in = size; 749 wpipe->pipe_buffer.out = 0; 750 wpipe->pipe_buffer.cnt = size; 751 wpipe->pipe_state &= ~PIPE_DIRECTW; 752 753 PIPE_GET_GIANT(wpipe); 754 bcopy((caddr_t) wpipe->pipe_map.kva + pos, 755 wpipe->pipe_buffer.buffer, size); 756 pipe_destroy_write_buffer(wpipe); 757 PIPE_DROP_GIANT(wpipe); 758 } 759 760 /* 761 * This implements the pipe buffer write mechanism. Note that only 762 * a direct write OR a normal pipe write can be pending at any given time. 763 * If there are any characters in the pipe buffer, the direct write will 764 * be deferred until the receiving process grabs all of the bytes from 765 * the pipe buffer. Then the direct mapping write is set-up. 766 */ 767 static int 768 pipe_direct_write(wpipe, uio) 769 struct pipe *wpipe; 770 struct uio *uio; 771 { 772 int error; 773 774 retry: 775 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 776 while (wpipe->pipe_state & PIPE_DIRECTW) { 777 if (wpipe->pipe_state & PIPE_WANTR) { 778 wpipe->pipe_state &= ~PIPE_WANTR; 779 wakeup(wpipe); 780 } 781 wpipe->pipe_state |= PIPE_WANTW; 782 error = msleep(wpipe, PIPE_MTX(wpipe), 783 PRIBIO | PCATCH, "pipdww", 0); 784 if (error) 785 goto error1; 786 if (wpipe->pipe_state & PIPE_EOF) { 787 error = EPIPE; 788 goto error1; 789 } 790 } 791 wpipe->pipe_map.cnt = 0; /* transfer not ready yet */ 792 if (wpipe->pipe_buffer.cnt > 0) { 793 if (wpipe->pipe_state & PIPE_WANTR) { 794 wpipe->pipe_state &= ~PIPE_WANTR; 795 wakeup(wpipe); 796 } 797 798 wpipe->pipe_state |= PIPE_WANTW; 799 error = msleep(wpipe, PIPE_MTX(wpipe), 800 PRIBIO | PCATCH, "pipdwc", 0); 801 if (error) 802 goto error1; 803 if (wpipe->pipe_state & PIPE_EOF) { 804 error = EPIPE; 805 goto error1; 806 } 807 goto retry; 808 } 809 810 wpipe->pipe_state |= PIPE_DIRECTW; 811 812 pipelock(wpipe, 0); 813 PIPE_GET_GIANT(wpipe); 814 error = pipe_build_write_buffer(wpipe, uio); 815 PIPE_DROP_GIANT(wpipe); 816 pipeunlock(wpipe); 817 if (error) { 818 wpipe->pipe_state &= ~PIPE_DIRECTW; 819 goto error1; 820 } 821 822 error = 0; 823 while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) { 824 if (wpipe->pipe_state & PIPE_EOF) { 825 pipelock(wpipe, 0); 826 PIPE_GET_GIANT(wpipe); 827 pipe_destroy_write_buffer(wpipe); 828 PIPE_DROP_GIANT(wpipe); 829 pipeunlock(wpipe); 830 pipeselwakeup(wpipe); 831 error = EPIPE; 832 goto error1; 833 } 834 if (wpipe->pipe_state & PIPE_WANTR) { 835 wpipe->pipe_state &= ~PIPE_WANTR; 836 wakeup(wpipe); 837 } 838 pipeselwakeup(wpipe); 839 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH, 840 "pipdwt", 0); 841 } 842 843 pipelock(wpipe,0); 844 if (wpipe->pipe_state & PIPE_DIRECTW) { 845 /* 846 * this bit of trickery substitutes a kernel buffer for 847 * the process that might be going away. 848 */ 849 pipe_clone_write_buffer(wpipe); 850 } else { 851 PIPE_GET_GIANT(wpipe); 852 pipe_destroy_write_buffer(wpipe); 853 PIPE_DROP_GIANT(wpipe); 854 } 855 pipeunlock(wpipe); 856 return (error); 857 858 error1: 859 wakeup(wpipe); 860 return (error); 861 } 862 #endif 863 864 static int 865 pipe_write(fp, uio, active_cred, flags, td) 866 struct file *fp; 867 struct uio *uio; 868 struct ucred *active_cred; 869 struct thread *td; 870 int flags; 871 { 872 int error = 0; 873 int orig_resid; 874 struct pipe *wpipe, *rpipe; 875 876 rpipe = (struct pipe *) fp->f_data; 877 wpipe = rpipe->pipe_peer; 878 879 PIPE_LOCK(rpipe); 880 /* 881 * detect loss of pipe read side, issue SIGPIPE if lost. 882 */ 883 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { 884 PIPE_UNLOCK(rpipe); 885 return (EPIPE); 886 } 887 #ifdef MAC 888 error = mac_check_pipe_write(active_cred, wpipe); 889 if (error) { 890 PIPE_UNLOCK(rpipe); 891 return (error); 892 } 893 #endif 894 ++wpipe->pipe_busy; 895 896 /* 897 * If it is advantageous to resize the pipe buffer, do 898 * so. 899 */ 900 if ((uio->uio_resid > PIPE_SIZE) && 901 (nbigpipe < LIMITBIGPIPES) && 902 (wpipe->pipe_state & PIPE_DIRECTW) == 0 && 903 (wpipe->pipe_buffer.size <= PIPE_SIZE) && 904 (wpipe->pipe_buffer.cnt == 0)) { 905 906 if ((error = pipelock(wpipe, 1)) == 0) { 907 PIPE_GET_GIANT(wpipe); 908 if (pipespace(wpipe, BIG_PIPE_SIZE) == 0) 909 nbigpipe++; 910 PIPE_DROP_GIANT(wpipe); 911 pipeunlock(wpipe); 912 } 913 } 914 915 /* 916 * If an early error occured unbusy and return, waking up any pending 917 * readers. 918 */ 919 if (error) { 920 --wpipe->pipe_busy; 921 if ((wpipe->pipe_busy == 0) && 922 (wpipe->pipe_state & PIPE_WANT)) { 923 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 924 wakeup(wpipe); 925 } 926 PIPE_UNLOCK(rpipe); 927 return(error); 928 } 929 930 orig_resid = uio->uio_resid; 931 932 while (uio->uio_resid) { 933 int space; 934 935 #ifndef PIPE_NODIRECT 936 /* 937 * If the transfer is large, we can gain performance if 938 * we do process-to-process copies directly. 939 * If the write is non-blocking, we don't use the 940 * direct write mechanism. 941 * 942 * The direct write mechanism will detect the reader going 943 * away on us. 944 */ 945 if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT) && 946 (fp->f_flag & FNONBLOCK) == 0 && 947 (wpipe->pipe_map.kva || (amountpipekva < LIMITPIPEKVA)) && 948 (uio->uio_iov->iov_len >= PIPE_MINDIRECT)) { 949 error = pipe_direct_write(wpipe, uio); 950 if (error) 951 break; 952 continue; 953 } 954 #endif 955 956 /* 957 * Pipe buffered writes cannot be coincidental with 958 * direct writes. We wait until the currently executing 959 * direct write is completed before we start filling the 960 * pipe buffer. We break out if a signal occurs or the 961 * reader goes away. 962 */ 963 retrywrite: 964 while (wpipe->pipe_state & PIPE_DIRECTW) { 965 if (wpipe->pipe_state & PIPE_WANTR) { 966 wpipe->pipe_state &= ~PIPE_WANTR; 967 wakeup(wpipe); 968 } 969 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH, 970 "pipbww", 0); 971 if (wpipe->pipe_state & PIPE_EOF) 972 break; 973 if (error) 974 break; 975 } 976 if (wpipe->pipe_state & PIPE_EOF) { 977 error = EPIPE; 978 break; 979 } 980 981 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 982 983 /* Writes of size <= PIPE_BUF must be atomic. */ 984 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 985 space = 0; 986 987 if (space > 0 && (wpipe->pipe_buffer.cnt < PIPE_SIZE)) { 988 if ((error = pipelock(wpipe,1)) == 0) { 989 int size; /* Transfer size */ 990 int segsize; /* first segment to transfer */ 991 992 /* 993 * It is possible for a direct write to 994 * slip in on us... handle it here... 995 */ 996 if (wpipe->pipe_state & PIPE_DIRECTW) { 997 pipeunlock(wpipe); 998 goto retrywrite; 999 } 1000 /* 1001 * If a process blocked in uiomove, our 1002 * value for space might be bad. 1003 * 1004 * XXX will we be ok if the reader has gone 1005 * away here? 1006 */ 1007 if (space > wpipe->pipe_buffer.size - 1008 wpipe->pipe_buffer.cnt) { 1009 pipeunlock(wpipe); 1010 goto retrywrite; 1011 } 1012 1013 /* 1014 * Transfer size is minimum of uio transfer 1015 * and free space in pipe buffer. 1016 */ 1017 if (space > uio->uio_resid) 1018 size = uio->uio_resid; 1019 else 1020 size = space; 1021 /* 1022 * First segment to transfer is minimum of 1023 * transfer size and contiguous space in 1024 * pipe buffer. If first segment to transfer 1025 * is less than the transfer size, we've got 1026 * a wraparound in the buffer. 1027 */ 1028 segsize = wpipe->pipe_buffer.size - 1029 wpipe->pipe_buffer.in; 1030 if (segsize > size) 1031 segsize = size; 1032 1033 /* Transfer first segment */ 1034 1035 PIPE_UNLOCK(rpipe); 1036 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 1037 segsize, uio); 1038 PIPE_LOCK(rpipe); 1039 1040 if (error == 0 && segsize < size) { 1041 /* 1042 * Transfer remaining part now, to 1043 * support atomic writes. Wraparound 1044 * happened. 1045 */ 1046 if (wpipe->pipe_buffer.in + segsize != 1047 wpipe->pipe_buffer.size) 1048 panic("Expected pipe buffer wraparound disappeared"); 1049 1050 PIPE_UNLOCK(rpipe); 1051 error = uiomove(&wpipe->pipe_buffer.buffer[0], 1052 size - segsize, uio); 1053 PIPE_LOCK(rpipe); 1054 } 1055 if (error == 0) { 1056 wpipe->pipe_buffer.in += size; 1057 if (wpipe->pipe_buffer.in >= 1058 wpipe->pipe_buffer.size) { 1059 if (wpipe->pipe_buffer.in != size - segsize + wpipe->pipe_buffer.size) 1060 panic("Expected wraparound bad"); 1061 wpipe->pipe_buffer.in = size - segsize; 1062 } 1063 1064 wpipe->pipe_buffer.cnt += size; 1065 if (wpipe->pipe_buffer.cnt > wpipe->pipe_buffer.size) 1066 panic("Pipe buffer overflow"); 1067 1068 } 1069 pipeunlock(wpipe); 1070 } 1071 if (error) 1072 break; 1073 1074 } else { 1075 /* 1076 * If the "read-side" has been blocked, wake it up now. 1077 */ 1078 if (wpipe->pipe_state & PIPE_WANTR) { 1079 wpipe->pipe_state &= ~PIPE_WANTR; 1080 wakeup(wpipe); 1081 } 1082 1083 /* 1084 * don't block on non-blocking I/O 1085 */ 1086 if (fp->f_flag & FNONBLOCK) { 1087 error = EAGAIN; 1088 break; 1089 } 1090 1091 /* 1092 * We have no more space and have something to offer, 1093 * wake up select/poll. 1094 */ 1095 pipeselwakeup(wpipe); 1096 1097 wpipe->pipe_state |= PIPE_WANTW; 1098 error = msleep(wpipe, PIPE_MTX(rpipe), 1099 PRIBIO | PCATCH, "pipewr", 0); 1100 if (error != 0) 1101 break; 1102 /* 1103 * If read side wants to go away, we just issue a signal 1104 * to ourselves. 1105 */ 1106 if (wpipe->pipe_state & PIPE_EOF) { 1107 error = EPIPE; 1108 break; 1109 } 1110 } 1111 } 1112 1113 --wpipe->pipe_busy; 1114 1115 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 1116 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 1117 wakeup(wpipe); 1118 } else if (wpipe->pipe_buffer.cnt > 0) { 1119 /* 1120 * If we have put any characters in the buffer, we wake up 1121 * the reader. 1122 */ 1123 if (wpipe->pipe_state & PIPE_WANTR) { 1124 wpipe->pipe_state &= ~PIPE_WANTR; 1125 wakeup(wpipe); 1126 } 1127 } 1128 1129 /* 1130 * Don't return EPIPE if I/O was successful 1131 */ 1132 if ((wpipe->pipe_buffer.cnt == 0) && 1133 (uio->uio_resid == 0) && 1134 (error == EPIPE)) { 1135 error = 0; 1136 } 1137 1138 if (error == 0) 1139 vfs_timestamp(&wpipe->pipe_mtime); 1140 1141 /* 1142 * We have something to offer, 1143 * wake up select/poll. 1144 */ 1145 if (wpipe->pipe_buffer.cnt) 1146 pipeselwakeup(wpipe); 1147 1148 PIPE_UNLOCK(rpipe); 1149 return (error); 1150 } 1151 1152 /* 1153 * we implement a very minimal set of ioctls for compatibility with sockets. 1154 */ 1155 static int 1156 pipe_ioctl(fp, cmd, data, active_cred, td) 1157 struct file *fp; 1158 u_long cmd; 1159 void *data; 1160 struct ucred *active_cred; 1161 struct thread *td; 1162 { 1163 struct pipe *mpipe = (struct pipe *)fp->f_data; 1164 #ifdef MAC 1165 int error; 1166 #endif 1167 1168 PIPE_LOCK(mpipe); 1169 1170 #ifdef MAC 1171 error = mac_check_pipe_ioctl(active_cred, mpipe, cmd, data); 1172 if (error) 1173 return (error); 1174 #endif 1175 1176 switch (cmd) { 1177 1178 case FIONBIO: 1179 PIPE_UNLOCK(mpipe); 1180 return (0); 1181 1182 case FIOASYNC: 1183 if (*(int *)data) { 1184 mpipe->pipe_state |= PIPE_ASYNC; 1185 } else { 1186 mpipe->pipe_state &= ~PIPE_ASYNC; 1187 } 1188 PIPE_UNLOCK(mpipe); 1189 return (0); 1190 1191 case FIONREAD: 1192 if (mpipe->pipe_state & PIPE_DIRECTW) 1193 *(int *)data = mpipe->pipe_map.cnt; 1194 else 1195 *(int *)data = mpipe->pipe_buffer.cnt; 1196 PIPE_UNLOCK(mpipe); 1197 return (0); 1198 1199 case FIOSETOWN: 1200 PIPE_UNLOCK(mpipe); 1201 return (fsetown(*(int *)data, &mpipe->pipe_sigio)); 1202 1203 case FIOGETOWN: 1204 PIPE_UNLOCK(mpipe); 1205 *(int *)data = fgetown(&mpipe->pipe_sigio); 1206 return (0); 1207 1208 /* This is deprecated, FIOSETOWN should be used instead. */ 1209 case TIOCSPGRP: 1210 PIPE_UNLOCK(mpipe); 1211 return (fsetown(-(*(int *)data), &mpipe->pipe_sigio)); 1212 1213 /* This is deprecated, FIOGETOWN should be used instead. */ 1214 case TIOCGPGRP: 1215 PIPE_UNLOCK(mpipe); 1216 *(int *)data = -fgetown(&mpipe->pipe_sigio); 1217 return (0); 1218 1219 } 1220 PIPE_UNLOCK(mpipe); 1221 return (ENOTTY); 1222 } 1223 1224 static int 1225 pipe_poll(fp, events, active_cred, td) 1226 struct file *fp; 1227 int events; 1228 struct ucred *active_cred; 1229 struct thread *td; 1230 { 1231 struct pipe *rpipe = (struct pipe *)fp->f_data; 1232 struct pipe *wpipe; 1233 int revents = 0; 1234 #ifdef MAC 1235 int error; 1236 #endif 1237 1238 wpipe = rpipe->pipe_peer; 1239 PIPE_LOCK(rpipe); 1240 #ifdef MAC 1241 error = mac_check_pipe_poll(active_cred, rpipe); 1242 if (error) 1243 goto locked_error; 1244 #endif 1245 if (events & (POLLIN | POLLRDNORM)) 1246 if ((rpipe->pipe_state & PIPE_DIRECTW) || 1247 (rpipe->pipe_buffer.cnt > 0) || 1248 (rpipe->pipe_state & PIPE_EOF)) 1249 revents |= events & (POLLIN | POLLRDNORM); 1250 1251 if (events & (POLLOUT | POLLWRNORM)) 1252 if (wpipe == NULL || (wpipe->pipe_state & PIPE_EOF) || 1253 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) && 1254 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF)) 1255 revents |= events & (POLLOUT | POLLWRNORM); 1256 1257 if ((rpipe->pipe_state & PIPE_EOF) || 1258 (wpipe == NULL) || 1259 (wpipe->pipe_state & PIPE_EOF)) 1260 revents |= POLLHUP; 1261 1262 if (revents == 0) { 1263 if (events & (POLLIN | POLLRDNORM)) { 1264 selrecord(td, &rpipe->pipe_sel); 1265 rpipe->pipe_state |= PIPE_SEL; 1266 } 1267 1268 if (events & (POLLOUT | POLLWRNORM)) { 1269 selrecord(td, &wpipe->pipe_sel); 1270 wpipe->pipe_state |= PIPE_SEL; 1271 } 1272 } 1273 #ifdef MAC 1274 locked_error: 1275 #endif 1276 PIPE_UNLOCK(rpipe); 1277 1278 return (revents); 1279 } 1280 1281 /* 1282 * We shouldn't need locks here as we're doing a read and this should 1283 * be a natural race. 1284 */ 1285 static int 1286 pipe_stat(fp, ub, active_cred, td) 1287 struct file *fp; 1288 struct stat *ub; 1289 struct ucred *active_cred; 1290 struct thread *td; 1291 { 1292 struct pipe *pipe = (struct pipe *)fp->f_data; 1293 #ifdef MAC 1294 int error; 1295 1296 PIPE_LOCK(pipe); 1297 error = mac_check_pipe_stat(active_cred, pipe); 1298 PIPE_UNLOCK(pipe); 1299 if (error) 1300 return (error); 1301 #endif 1302 bzero(ub, sizeof(*ub)); 1303 ub->st_mode = S_IFIFO; 1304 ub->st_blksize = pipe->pipe_buffer.size; 1305 ub->st_size = pipe->pipe_buffer.cnt; 1306 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize; 1307 ub->st_atimespec = pipe->pipe_atime; 1308 ub->st_mtimespec = pipe->pipe_mtime; 1309 ub->st_ctimespec = pipe->pipe_ctime; 1310 ub->st_uid = fp->f_cred->cr_uid; 1311 ub->st_gid = fp->f_cred->cr_gid; 1312 /* 1313 * Left as 0: st_dev, st_ino, st_nlink, st_rdev, st_flags, st_gen. 1314 * XXX (st_dev, st_ino) should be unique. 1315 */ 1316 return (0); 1317 } 1318 1319 /* ARGSUSED */ 1320 static int 1321 pipe_close(fp, td) 1322 struct file *fp; 1323 struct thread *td; 1324 { 1325 struct pipe *cpipe = (struct pipe *)fp->f_data; 1326 1327 fp->f_ops = &badfileops; 1328 fp->f_data = NULL; 1329 funsetown(&cpipe->pipe_sigio); 1330 pipeclose(cpipe); 1331 return (0); 1332 } 1333 1334 static void 1335 pipe_free_kmem(cpipe) 1336 struct pipe *cpipe; 1337 { 1338 1339 GIANT_REQUIRED; 1340 KASSERT(cpipe->pipe_mtxp == NULL || !mtx_owned(PIPE_MTX(cpipe)), 1341 ("pipespace: pipe mutex locked")); 1342 1343 if (cpipe->pipe_buffer.buffer != NULL) { 1344 if (cpipe->pipe_buffer.size > PIPE_SIZE) 1345 --nbigpipe; 1346 amountpipekva -= cpipe->pipe_buffer.size; 1347 kmem_free(kernel_map, 1348 (vm_offset_t)cpipe->pipe_buffer.buffer, 1349 cpipe->pipe_buffer.size); 1350 cpipe->pipe_buffer.buffer = NULL; 1351 } 1352 #ifndef PIPE_NODIRECT 1353 if (cpipe->pipe_map.kva != 0) { 1354 amountpipekva -= cpipe->pipe_buffer.size + PAGE_SIZE; 1355 kmem_free(kernel_map, 1356 cpipe->pipe_map.kva, 1357 cpipe->pipe_buffer.size + PAGE_SIZE); 1358 cpipe->pipe_map.cnt = 0; 1359 cpipe->pipe_map.kva = 0; 1360 cpipe->pipe_map.pos = 0; 1361 cpipe->pipe_map.npages = 0; 1362 } 1363 #endif 1364 } 1365 1366 /* 1367 * shutdown the pipe 1368 */ 1369 static void 1370 pipeclose(cpipe) 1371 struct pipe *cpipe; 1372 { 1373 struct pipe *ppipe; 1374 int hadpeer; 1375 1376 if (cpipe == NULL) 1377 return; 1378 1379 hadpeer = 0; 1380 1381 /* partially created pipes won't have a valid mutex. */ 1382 if (PIPE_MTX(cpipe) != NULL) 1383 PIPE_LOCK(cpipe); 1384 1385 pipeselwakeup(cpipe); 1386 1387 /* 1388 * If the other side is blocked, wake it up saying that 1389 * we want to close it down. 1390 */ 1391 while (cpipe->pipe_busy) { 1392 wakeup(cpipe); 1393 cpipe->pipe_state |= PIPE_WANT | PIPE_EOF; 1394 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0); 1395 } 1396 1397 #ifdef MAC 1398 if (cpipe->pipe_label != NULL && cpipe->pipe_peer == NULL) 1399 mac_destroy_pipe(cpipe); 1400 #endif 1401 1402 /* 1403 * Disconnect from peer 1404 */ 1405 if ((ppipe = cpipe->pipe_peer) != NULL) { 1406 hadpeer++; 1407 pipeselwakeup(ppipe); 1408 1409 ppipe->pipe_state |= PIPE_EOF; 1410 wakeup(ppipe); 1411 KNOTE(&ppipe->pipe_sel.si_note, 0); 1412 ppipe->pipe_peer = NULL; 1413 } 1414 /* 1415 * free resources 1416 */ 1417 if (PIPE_MTX(cpipe) != NULL) { 1418 PIPE_UNLOCK(cpipe); 1419 if (!hadpeer) { 1420 mtx_destroy(PIPE_MTX(cpipe)); 1421 free(PIPE_MTX(cpipe), M_TEMP); 1422 } 1423 } 1424 mtx_lock(&Giant); 1425 pipe_free_kmem(cpipe); 1426 uma_zfree(pipe_zone, cpipe); 1427 mtx_unlock(&Giant); 1428 } 1429 1430 /*ARGSUSED*/ 1431 static int 1432 pipe_kqfilter(struct file *fp, struct knote *kn) 1433 { 1434 struct pipe *cpipe; 1435 1436 cpipe = (struct pipe *)kn->kn_fp->f_data; 1437 switch (kn->kn_filter) { 1438 case EVFILT_READ: 1439 kn->kn_fop = &pipe_rfiltops; 1440 break; 1441 case EVFILT_WRITE: 1442 kn->kn_fop = &pipe_wfiltops; 1443 cpipe = cpipe->pipe_peer; 1444 if (cpipe == NULL) 1445 /* other end of pipe has been closed */ 1446 return (EBADF); 1447 break; 1448 default: 1449 return (1); 1450 } 1451 kn->kn_hook = cpipe; 1452 1453 PIPE_LOCK(cpipe); 1454 SLIST_INSERT_HEAD(&cpipe->pipe_sel.si_note, kn, kn_selnext); 1455 PIPE_UNLOCK(cpipe); 1456 return (0); 1457 } 1458 1459 static void 1460 filt_pipedetach(struct knote *kn) 1461 { 1462 struct pipe *cpipe = (struct pipe *)kn->kn_hook; 1463 1464 PIPE_LOCK(cpipe); 1465 SLIST_REMOVE(&cpipe->pipe_sel.si_note, kn, knote, kn_selnext); 1466 PIPE_UNLOCK(cpipe); 1467 } 1468 1469 /*ARGSUSED*/ 1470 static int 1471 filt_piperead(struct knote *kn, long hint) 1472 { 1473 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; 1474 struct pipe *wpipe = rpipe->pipe_peer; 1475 1476 PIPE_LOCK(rpipe); 1477 kn->kn_data = rpipe->pipe_buffer.cnt; 1478 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) 1479 kn->kn_data = rpipe->pipe_map.cnt; 1480 1481 if ((rpipe->pipe_state & PIPE_EOF) || 1482 (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { 1483 kn->kn_flags |= EV_EOF; 1484 PIPE_UNLOCK(rpipe); 1485 return (1); 1486 } 1487 PIPE_UNLOCK(rpipe); 1488 return (kn->kn_data > 0); 1489 } 1490 1491 /*ARGSUSED*/ 1492 static int 1493 filt_pipewrite(struct knote *kn, long hint) 1494 { 1495 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; 1496 struct pipe *wpipe = rpipe->pipe_peer; 1497 1498 PIPE_LOCK(rpipe); 1499 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { 1500 kn->kn_data = 0; 1501 kn->kn_flags |= EV_EOF; 1502 PIPE_UNLOCK(rpipe); 1503 return (1); 1504 } 1505 kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1506 if (wpipe->pipe_state & PIPE_DIRECTW) 1507 kn->kn_data = 0; 1508 1509 PIPE_UNLOCK(rpipe); 1510 return (kn->kn_data >= PIPE_BUF); 1511 }
Cache object: b4c43087ef33d34d40ef5e67da15fa82
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