sys_pipe.c revision 76827
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: head/sys/kern/sys_pipe.c 76827 2001-05-19 01:28:09Z 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 <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/lock.h> 59#include <sys/mutex.h> 60#include <sys/ttycom.h> 61#include <sys/stat.h> 62#include <sys/poll.h> 63#include <sys/selinfo.h> 64#include <sys/signalvar.h> 65#include <sys/sysproto.h> 66#include <sys/pipe.h> 67#include <sys/proc.h> 68#include <sys/vnode.h> 69#include <sys/uio.h> 70#include <sys/event.h> 71 72#include <vm/vm.h> 73#include <vm/vm_param.h> 74#include <vm/vm_object.h> 75#include <vm/vm_kern.h> 76#include <vm/vm_extern.h> 77#include <vm/pmap.h> 78#include <vm/vm_map.h> 79#include <vm/vm_page.h> 80#include <vm/vm_zone.h> 81 82/* 83 * Use this define if you want to disable *fancy* VM things. Expect an 84 * approx 30% decrease in transfer rate. This could be useful for 85 * NetBSD or OpenBSD. 86 */ 87/* #define PIPE_NODIRECT */ 88 89/* 90 * interfaces to the outside world 91 */ 92static int pipe_read __P((struct file *fp, struct uio *uio, 93 struct ucred *cred, int flags, struct proc *p)); 94static int pipe_write __P((struct file *fp, struct uio *uio, 95 struct ucred *cred, int flags, struct proc *p)); 96static int pipe_close __P((struct file *fp, struct proc *p)); 97static int pipe_poll __P((struct file *fp, int events, struct ucred *cred, 98 struct proc *p)); 99static int pipe_kqfilter __P((struct file *fp, struct knote *kn)); 100static int pipe_stat __P((struct file *fp, struct stat *sb, struct proc *p)); 101static int pipe_ioctl __P((struct file *fp, u_long cmd, caddr_t data, struct proc *p)); 102 103static struct fileops pipeops = { 104 pipe_read, pipe_write, pipe_ioctl, pipe_poll, pipe_kqfilter, 105 pipe_stat, pipe_close 106}; 107 108static void filt_pipedetach(struct knote *kn); 109static int filt_piperead(struct knote *kn, long hint); 110static int filt_pipewrite(struct knote *kn, long hint); 111 112static struct filterops pipe_rfiltops = 113 { 1, NULL, filt_pipedetach, filt_piperead }; 114static struct filterops pipe_wfiltops = 115 { 1, NULL, filt_pipedetach, filt_pipewrite }; 116 117 118/* 119 * Default pipe buffer size(s), this can be kind-of large now because pipe 120 * space is pageable. The pipe code will try to maintain locality of 121 * reference for performance reasons, so small amounts of outstanding I/O 122 * will not wipe the cache. 123 */ 124#define MINPIPESIZE (PIPE_SIZE/3) 125#define MAXPIPESIZE (2*PIPE_SIZE/3) 126 127/* 128 * Maximum amount of kva for pipes -- this is kind-of a soft limit, but 129 * is there so that on large systems, we don't exhaust it. 130 */ 131#define MAXPIPEKVA (8*1024*1024) 132 133/* 134 * Limit for direct transfers, we cannot, of course limit 135 * the amount of kva for pipes in general though. 136 */ 137#define LIMITPIPEKVA (16*1024*1024) 138 139/* 140 * Limit the number of "big" pipes 141 */ 142#define LIMITBIGPIPES 32 143static int nbigpipe; 144 145static int amountpipekva; 146 147static void pipeclose __P((struct pipe *cpipe)); 148static void pipe_free_kmem __P((struct pipe *cpipe)); 149static int pipe_create __P((struct pipe **cpipep)); 150static __inline int pipelock __P((struct pipe *cpipe, int catch)); 151static __inline void pipeunlock __P((struct pipe *cpipe)); 152static __inline void pipeselwakeup __P((struct pipe *cpipe)); 153#ifndef PIPE_NODIRECT 154static int pipe_build_write_buffer __P((struct pipe *wpipe, struct uio *uio)); 155static void pipe_destroy_write_buffer __P((struct pipe *wpipe)); 156static int pipe_direct_write __P((struct pipe *wpipe, struct uio *uio)); 157static void pipe_clone_write_buffer __P((struct pipe *wpipe)); 158#endif 159static int pipespace __P((struct pipe *cpipe, int size)); 160 161static vm_zone_t pipe_zone; 162 163/* 164 * The pipe system call for the DTYPE_PIPE type of pipes 165 */ 166 167/* ARGSUSED */ 168int 169pipe(p, uap) 170 struct proc *p; 171 struct pipe_args /* { 172 int dummy; 173 } */ *uap; 174{ 175 struct filedesc *fdp = p->p_fd; 176 struct file *rf, *wf; 177 struct pipe *rpipe, *wpipe; 178 int fd, error; 179 180 if (pipe_zone == NULL) 181 pipe_zone = zinit("PIPE", sizeof(struct pipe), 0, 0, 4); 182 183 rpipe = wpipe = NULL; 184 if (pipe_create(&rpipe) || pipe_create(&wpipe)) { 185 pipeclose(rpipe); 186 pipeclose(wpipe); 187 return (ENFILE); 188 } 189 190 rpipe->pipe_state |= PIPE_DIRECTOK; 191 wpipe->pipe_state |= PIPE_DIRECTOK; 192 193 error = falloc(p, &rf, &fd); 194 if (error) { 195 pipeclose(rpipe); 196 pipeclose(wpipe); 197 return (error); 198 } 199 fhold(rf); 200 p->p_retval[0] = fd; 201 202 /* 203 * Warning: once we've gotten past allocation of the fd for the 204 * read-side, we can only drop the read side via fdrop() in order 205 * to avoid races against processes which manage to dup() the read 206 * side while we are blocked trying to allocate the write side. 207 */ 208 rf->f_flag = FREAD | FWRITE; 209 rf->f_type = DTYPE_PIPE; 210 rf->f_data = (caddr_t)rpipe; 211 rf->f_ops = &pipeops; 212 error = falloc(p, &wf, &fd); 213 if (error) { 214 if (fdp->fd_ofiles[p->p_retval[0]] == rf) { 215 fdp->fd_ofiles[p->p_retval[0]] = NULL; 216 fdrop(rf, p); 217 } 218 fdrop(rf, p); 219 /* rpipe has been closed by fdrop(). */ 220 pipeclose(wpipe); 221 return (error); 222 } 223 wf->f_flag = FREAD | FWRITE; 224 wf->f_type = DTYPE_PIPE; 225 wf->f_data = (caddr_t)wpipe; 226 wf->f_ops = &pipeops; 227 p->p_retval[1] = fd; 228 229 rpipe->pipe_peer = wpipe; 230 wpipe->pipe_peer = rpipe; 231 fdrop(rf, p); 232 233 return (0); 234} 235 236/* 237 * Allocate kva for pipe circular buffer, the space is pageable 238 * This routine will 'realloc' the size of a pipe safely, if it fails 239 * it will retain the old buffer. 240 * If it fails it will return ENOMEM. 241 */ 242static int 243pipespace(cpipe, size) 244 struct pipe *cpipe; 245 int size; 246{ 247 struct vm_object *object; 248 caddr_t buffer; 249 int npages, error; 250 251 npages = round_page(size)/PAGE_SIZE; 252 /* 253 * Create an object, I don't like the idea of paging to/from 254 * kernel_object. 255 * XXX -- minor change needed here for NetBSD/OpenBSD VM systems. 256 */ 257 mtx_lock(&vm_mtx); 258 object = vm_object_allocate(OBJT_DEFAULT, npages); 259 buffer = (caddr_t) vm_map_min(kernel_map); 260 261 /* 262 * Insert the object into the kernel map, and allocate kva for it. 263 * The map entry is, by default, pageable. 264 * XXX -- minor change needed here for NetBSD/OpenBSD VM systems. 265 */ 266 error = vm_map_find(kernel_map, object, 0, 267 (vm_offset_t *) &buffer, size, 1, 268 VM_PROT_ALL, VM_PROT_ALL, 0); 269 mtx_unlock(&vm_mtx); 270 271 if (error != KERN_SUCCESS) { 272 vm_object_deallocate(object); 273 return (ENOMEM); 274 } 275 276 /* free old resources if we're resizing */ 277 pipe_free_kmem(cpipe); 278 cpipe->pipe_buffer.object = object; 279 cpipe->pipe_buffer.buffer = buffer; 280 cpipe->pipe_buffer.size = size; 281 cpipe->pipe_buffer.in = 0; 282 cpipe->pipe_buffer.out = 0; 283 cpipe->pipe_buffer.cnt = 0; 284 amountpipekva += cpipe->pipe_buffer.size; 285 return (0); 286} 287 288/* 289 * initialize and allocate VM and memory for pipe 290 */ 291static int 292pipe_create(cpipep) 293 struct pipe **cpipep; 294{ 295 struct pipe *cpipe; 296 int error; 297 298 *cpipep = zalloc(pipe_zone); 299 if (*cpipep == NULL) 300 return (ENOMEM); 301 302 cpipe = *cpipep; 303 304 /* so pipespace()->pipe_free_kmem() doesn't follow junk pointer */ 305 cpipe->pipe_buffer.object = NULL; 306#ifndef PIPE_NODIRECT 307 cpipe->pipe_map.kva = NULL; 308#endif 309 /* 310 * protect so pipeclose() doesn't follow a junk pointer 311 * if pipespace() fails. 312 */ 313 bzero(&cpipe->pipe_sel, sizeof(cpipe->pipe_sel)); 314 cpipe->pipe_state = 0; 315 cpipe->pipe_peer = NULL; 316 cpipe->pipe_busy = 0; 317 318#ifndef PIPE_NODIRECT 319 /* 320 * pipe data structure initializations to support direct pipe I/O 321 */ 322 cpipe->pipe_map.cnt = 0; 323 cpipe->pipe_map.kva = 0; 324 cpipe->pipe_map.pos = 0; 325 cpipe->pipe_map.npages = 0; 326 /* cpipe->pipe_map.ms[] = invalid */ 327#endif 328 329 error = pipespace(cpipe, PIPE_SIZE); 330 if (error) 331 return (error); 332 333 vfs_timestamp(&cpipe->pipe_ctime); 334 cpipe->pipe_atime = cpipe->pipe_ctime; 335 cpipe->pipe_mtime = cpipe->pipe_ctime; 336 337 return (0); 338} 339 340 341/* 342 * lock a pipe for I/O, blocking other access 343 */ 344static __inline int 345pipelock(cpipe, catch) 346 struct pipe *cpipe; 347 int catch; 348{ 349 int error; 350 351 while (cpipe->pipe_state & PIPE_LOCK) { 352 cpipe->pipe_state |= PIPE_LWANT; 353 error = tsleep(cpipe, catch ? (PRIBIO | PCATCH) : PRIBIO, 354 "pipelk", 0); 355 if (error != 0) 356 return (error); 357 } 358 cpipe->pipe_state |= PIPE_LOCK; 359 return (0); 360} 361 362/* 363 * unlock a pipe I/O lock 364 */ 365static __inline void 366pipeunlock(cpipe) 367 struct pipe *cpipe; 368{ 369 370 cpipe->pipe_state &= ~PIPE_LOCK; 371 if (cpipe->pipe_state & PIPE_LWANT) { 372 cpipe->pipe_state &= ~PIPE_LWANT; 373 wakeup(cpipe); 374 } 375} 376 377static __inline void 378pipeselwakeup(cpipe) 379 struct pipe *cpipe; 380{ 381 382 if (cpipe->pipe_state & PIPE_SEL) { 383 cpipe->pipe_state &= ~PIPE_SEL; 384 selwakeup(&cpipe->pipe_sel); 385 } 386 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) 387 pgsigio(cpipe->pipe_sigio, SIGIO, 0); 388 KNOTE(&cpipe->pipe_sel.si_note, 0); 389} 390 391/* ARGSUSED */ 392static int 393pipe_read(fp, uio, cred, flags, p) 394 struct file *fp; 395 struct uio *uio; 396 struct ucred *cred; 397 struct proc *p; 398 int flags; 399{ 400 struct pipe *rpipe = (struct pipe *) fp->f_data; 401 int error; 402 int nread = 0; 403 u_int size; 404 405 ++rpipe->pipe_busy; 406 error = pipelock(rpipe, 1); 407 if (error) 408 goto unlocked_error; 409 410 while (uio->uio_resid) { 411 /* 412 * normal pipe buffer receive 413 */ 414 if (rpipe->pipe_buffer.cnt > 0) { 415 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 416 if (size > rpipe->pipe_buffer.cnt) 417 size = rpipe->pipe_buffer.cnt; 418 if (size > (u_int) uio->uio_resid) 419 size = (u_int) uio->uio_resid; 420 421 error = uiomove(&rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 422 size, uio); 423 if (error) 424 break; 425 426 rpipe->pipe_buffer.out += size; 427 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 428 rpipe->pipe_buffer.out = 0; 429 430 rpipe->pipe_buffer.cnt -= size; 431 432 /* 433 * If there is no more to read in the pipe, reset 434 * its pointers to the beginning. This improves 435 * cache hit stats. 436 */ 437 if (rpipe->pipe_buffer.cnt == 0) { 438 rpipe->pipe_buffer.in = 0; 439 rpipe->pipe_buffer.out = 0; 440 } 441 nread += size; 442#ifndef PIPE_NODIRECT 443 /* 444 * Direct copy, bypassing a kernel buffer. 445 */ 446 } else if ((size = rpipe->pipe_map.cnt) && 447 (rpipe->pipe_state & PIPE_DIRECTW)) { 448 caddr_t va; 449 if (size > (u_int) uio->uio_resid) 450 size = (u_int) uio->uio_resid; 451 452 va = (caddr_t) rpipe->pipe_map.kva + 453 rpipe->pipe_map.pos; 454 error = uiomove(va, size, uio); 455 if (error) 456 break; 457 nread += size; 458 rpipe->pipe_map.pos += size; 459 rpipe->pipe_map.cnt -= size; 460 if (rpipe->pipe_map.cnt == 0) { 461 rpipe->pipe_state &= ~PIPE_DIRECTW; 462 wakeup(rpipe); 463 } 464#endif 465 } else { 466 /* 467 * detect EOF condition 468 * read returns 0 on EOF, no need to set error 469 */ 470 if (rpipe->pipe_state & PIPE_EOF) 471 break; 472 473 /* 474 * If the "write-side" has been blocked, wake it up now. 475 */ 476 if (rpipe->pipe_state & PIPE_WANTW) { 477 rpipe->pipe_state &= ~PIPE_WANTW; 478 wakeup(rpipe); 479 } 480 481 /* 482 * Break if some data was read. 483 */ 484 if (nread > 0) 485 break; 486 487 /* 488 * Unlock the pipe buffer for our remaining processing. We 489 * will either break out with an error or we will sleep and 490 * relock to loop. 491 */ 492 pipeunlock(rpipe); 493 494 /* 495 * Handle non-blocking mode operation or 496 * wait for more data. 497 */ 498 if (fp->f_flag & FNONBLOCK) { 499 error = EAGAIN; 500 } else { 501 rpipe->pipe_state |= PIPE_WANTR; 502 if ((error = tsleep(rpipe, PRIBIO|PCATCH, "piperd", 0)) == 0) 503 error = pipelock(rpipe, 1); 504 } 505 if (error) 506 goto unlocked_error; 507 } 508 } 509 pipeunlock(rpipe); 510 511 if (error == 0) 512 vfs_timestamp(&rpipe->pipe_atime); 513unlocked_error: 514 --rpipe->pipe_busy; 515 516 /* 517 * PIPE_WANT processing only makes sense if pipe_busy is 0. 518 */ 519 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 520 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 521 wakeup(rpipe); 522 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 523 /* 524 * Handle write blocking hysteresis. 525 */ 526 if (rpipe->pipe_state & PIPE_WANTW) { 527 rpipe->pipe_state &= ~PIPE_WANTW; 528 wakeup(rpipe); 529 } 530 } 531 532 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF) 533 pipeselwakeup(rpipe); 534 535 return (error); 536} 537 538#ifndef PIPE_NODIRECT 539/* 540 * Map the sending processes' buffer into kernel space and wire it. 541 * This is similar to a physical write operation. 542 */ 543static int 544pipe_build_write_buffer(wpipe, uio) 545 struct pipe *wpipe; 546 struct uio *uio; 547{ 548 u_int size; 549 int i; 550 vm_offset_t addr, endaddr, paddr; 551 552 size = (u_int) uio->uio_iov->iov_len; 553 if (size > wpipe->pipe_buffer.size) 554 size = wpipe->pipe_buffer.size; 555 556 endaddr = round_page((vm_offset_t)uio->uio_iov->iov_base + size); 557 mtx_lock(&vm_mtx); 558 addr = trunc_page((vm_offset_t)uio->uio_iov->iov_base); 559 for (i = 0; addr < endaddr; addr += PAGE_SIZE, i++) { 560 vm_page_t m; 561 562 if (vm_fault_quick((caddr_t)addr, VM_PROT_READ) < 0 || 563 (paddr = pmap_kextract(addr)) == 0) { 564 int j; 565 566 for (j = 0; j < i; j++) 567 vm_page_unwire(wpipe->pipe_map.ms[j], 1); 568 mtx_unlock(&vm_mtx); 569 return (EFAULT); 570 } 571 572 m = PHYS_TO_VM_PAGE(paddr); 573 vm_page_wire(m); 574 wpipe->pipe_map.ms[i] = m; 575 } 576 577/* 578 * set up the control block 579 */ 580 wpipe->pipe_map.npages = i; 581 wpipe->pipe_map.pos = 582 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 583 wpipe->pipe_map.cnt = size; 584 585/* 586 * and map the buffer 587 */ 588 if (wpipe->pipe_map.kva == 0) { 589 /* 590 * We need to allocate space for an extra page because the 591 * address range might (will) span pages at times. 592 */ 593 wpipe->pipe_map.kva = kmem_alloc_pageable(kernel_map, 594 wpipe->pipe_buffer.size + PAGE_SIZE); 595 amountpipekva += wpipe->pipe_buffer.size + PAGE_SIZE; 596 } 597 pmap_qenter(wpipe->pipe_map.kva, wpipe->pipe_map.ms, 598 wpipe->pipe_map.npages); 599 600 mtx_unlock(&vm_mtx); 601/* 602 * and update the uio data 603 */ 604 605 uio->uio_iov->iov_len -= size; 606 uio->uio_iov->iov_base += size; 607 if (uio->uio_iov->iov_len == 0) 608 uio->uio_iov++; 609 uio->uio_resid -= size; 610 uio->uio_offset += size; 611 return (0); 612} 613 614/* 615 * unmap and unwire the process buffer 616 */ 617static void 618pipe_destroy_write_buffer(wpipe) 619 struct pipe *wpipe; 620{ 621 int i; 622 623 if (wpipe->pipe_map.kva) { 624 pmap_qremove(wpipe->pipe_map.kva, wpipe->pipe_map.npages); 625 626 if (amountpipekva > MAXPIPEKVA) { 627 vm_offset_t kva = wpipe->pipe_map.kva; 628 wpipe->pipe_map.kva = 0; 629 kmem_free(kernel_map, kva, 630 wpipe->pipe_buffer.size + PAGE_SIZE); 631 amountpipekva -= wpipe->pipe_buffer.size + PAGE_SIZE; 632 } 633 } 634 mtx_lock(&vm_mtx); 635 for (i = 0; i < wpipe->pipe_map.npages; i++) 636 vm_page_unwire(wpipe->pipe_map.ms[i], 1); 637 mtx_unlock(&vm_mtx); 638} 639 640/* 641 * In the case of a signal, the writing process might go away. This 642 * code copies the data into the circular buffer so that the source 643 * pages can be freed without loss of data. 644 */ 645static void 646pipe_clone_write_buffer(wpipe) 647 struct pipe *wpipe; 648{ 649 int size; 650 int pos; 651 652 size = wpipe->pipe_map.cnt; 653 pos = wpipe->pipe_map.pos; 654 bcopy((caddr_t) wpipe->pipe_map.kva + pos, 655 (caddr_t) wpipe->pipe_buffer.buffer, size); 656 657 wpipe->pipe_buffer.in = size; 658 wpipe->pipe_buffer.out = 0; 659 wpipe->pipe_buffer.cnt = size; 660 wpipe->pipe_state &= ~PIPE_DIRECTW; 661 662 pipe_destroy_write_buffer(wpipe); 663} 664 665/* 666 * This implements the pipe buffer write mechanism. Note that only 667 * a direct write OR a normal pipe write can be pending at any given time. 668 * If there are any characters in the pipe buffer, the direct write will 669 * be deferred until the receiving process grabs all of the bytes from 670 * the pipe buffer. Then the direct mapping write is set-up. 671 */ 672static int 673pipe_direct_write(wpipe, uio) 674 struct pipe *wpipe; 675 struct uio *uio; 676{ 677 int error; 678 679retry: 680 while (wpipe->pipe_state & PIPE_DIRECTW) { 681 if (wpipe->pipe_state & PIPE_WANTR) { 682 wpipe->pipe_state &= ~PIPE_WANTR; 683 wakeup(wpipe); 684 } 685 wpipe->pipe_state |= PIPE_WANTW; 686 error = tsleep(wpipe, PRIBIO | PCATCH, "pipdww", 0); 687 if (error) 688 goto error1; 689 if (wpipe->pipe_state & PIPE_EOF) { 690 error = EPIPE; 691 goto error1; 692 } 693 } 694 wpipe->pipe_map.cnt = 0; /* transfer not ready yet */ 695 if (wpipe->pipe_buffer.cnt > 0) { 696 if (wpipe->pipe_state & PIPE_WANTR) { 697 wpipe->pipe_state &= ~PIPE_WANTR; 698 wakeup(wpipe); 699 } 700 701 wpipe->pipe_state |= PIPE_WANTW; 702 error = tsleep(wpipe, PRIBIO | PCATCH, "pipdwc", 0); 703 if (error) 704 goto error1; 705 if (wpipe->pipe_state & PIPE_EOF) { 706 error = EPIPE; 707 goto error1; 708 } 709 goto retry; 710 } 711 712 wpipe->pipe_state |= PIPE_DIRECTW; 713 714 error = pipe_build_write_buffer(wpipe, uio); 715 if (error) { 716 wpipe->pipe_state &= ~PIPE_DIRECTW; 717 goto error1; 718 } 719 720 error = 0; 721 while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) { 722 if (wpipe->pipe_state & PIPE_EOF) { 723 pipelock(wpipe, 0); 724 pipe_destroy_write_buffer(wpipe); 725 pipeunlock(wpipe); 726 pipeselwakeup(wpipe); 727 error = EPIPE; 728 goto error1; 729 } 730 if (wpipe->pipe_state & PIPE_WANTR) { 731 wpipe->pipe_state &= ~PIPE_WANTR; 732 wakeup(wpipe); 733 } 734 pipeselwakeup(wpipe); 735 error = tsleep(wpipe, PRIBIO | PCATCH, "pipdwt", 0); 736 } 737 738 pipelock(wpipe,0); 739 if (wpipe->pipe_state & PIPE_DIRECTW) { 740 /* 741 * this bit of trickery substitutes a kernel buffer for 742 * the process that might be going away. 743 */ 744 pipe_clone_write_buffer(wpipe); 745 } else { 746 pipe_destroy_write_buffer(wpipe); 747 } 748 pipeunlock(wpipe); 749 return (error); 750 751error1: 752 wakeup(wpipe); 753 return (error); 754} 755#endif 756 757static int 758pipe_write(fp, uio, cred, flags, p) 759 struct file *fp; 760 struct uio *uio; 761 struct ucred *cred; 762 struct proc *p; 763 int flags; 764{ 765 int error = 0; 766 int orig_resid; 767 struct pipe *wpipe, *rpipe; 768 769 rpipe = (struct pipe *) fp->f_data; 770 wpipe = rpipe->pipe_peer; 771 772 /* 773 * detect loss of pipe read side, issue SIGPIPE if lost. 774 */ 775 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { 776 return (EPIPE); 777 } 778 779 /* 780 * If it is advantageous to resize the pipe buffer, do 781 * so. 782 */ 783 if ((uio->uio_resid > PIPE_SIZE) && 784 (nbigpipe < LIMITBIGPIPES) && 785 (wpipe->pipe_state & PIPE_DIRECTW) == 0 && 786 (wpipe->pipe_buffer.size <= PIPE_SIZE) && 787 (wpipe->pipe_buffer.cnt == 0)) { 788 789 if ((error = pipelock(wpipe,1)) == 0) { 790 if (pipespace(wpipe, BIG_PIPE_SIZE) == 0) 791 nbigpipe++; 792 pipeunlock(wpipe); 793 } else { 794 return (error); 795 } 796 } 797 798 KASSERT(wpipe->pipe_buffer.buffer != NULL, ("pipe buffer gone")); 799 800 ++wpipe->pipe_busy; 801 orig_resid = uio->uio_resid; 802 while (uio->uio_resid) { 803 int space; 804 805#ifndef PIPE_NODIRECT 806 /* 807 * If the transfer is large, we can gain performance if 808 * we do process-to-process copies directly. 809 * If the write is non-blocking, we don't use the 810 * direct write mechanism. 811 * 812 * The direct write mechanism will detect the reader going 813 * away on us. 814 */ 815 if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT) && 816 (fp->f_flag & FNONBLOCK) == 0 && 817 (wpipe->pipe_map.kva || (amountpipekva < LIMITPIPEKVA)) && 818 (uio->uio_iov->iov_len >= PIPE_MINDIRECT)) { 819 error = pipe_direct_write( wpipe, uio); 820 if (error) 821 break; 822 continue; 823 } 824#endif 825 826 /* 827 * Pipe buffered writes cannot be coincidental with 828 * direct writes. We wait until the currently executing 829 * direct write is completed before we start filling the 830 * pipe buffer. We break out if a signal occurs or the 831 * reader goes away. 832 */ 833 retrywrite: 834 while (wpipe->pipe_state & PIPE_DIRECTW) { 835 if (wpipe->pipe_state & PIPE_WANTR) { 836 wpipe->pipe_state &= ~PIPE_WANTR; 837 wakeup(wpipe); 838 } 839 error = tsleep(wpipe, PRIBIO | PCATCH, "pipbww", 0); 840 if (wpipe->pipe_state & PIPE_EOF) 841 break; 842 if (error) 843 break; 844 } 845 if (wpipe->pipe_state & PIPE_EOF) { 846 error = EPIPE; 847 break; 848 } 849 850 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 851 852 /* Writes of size <= PIPE_BUF must be atomic. */ 853 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 854 space = 0; 855 856 if (space > 0 && (wpipe->pipe_buffer.cnt < PIPE_SIZE)) { 857 if ((error = pipelock(wpipe,1)) == 0) { 858 int size; /* Transfer size */ 859 int segsize; /* first segment to transfer */ 860 861 /* 862 * It is possible for a direct write to 863 * slip in on us... handle it here... 864 */ 865 if (wpipe->pipe_state & PIPE_DIRECTW) { 866 pipeunlock(wpipe); 867 goto retrywrite; 868 } 869 /* 870 * If a process blocked in uiomove, our 871 * value for space might be bad. 872 * 873 * XXX will we be ok if the reader has gone 874 * away here? 875 */ 876 if (space > wpipe->pipe_buffer.size - 877 wpipe->pipe_buffer.cnt) { 878 pipeunlock(wpipe); 879 goto retrywrite; 880 } 881 882 /* 883 * Transfer size is minimum of uio transfer 884 * and free space in pipe buffer. 885 */ 886 if (space > uio->uio_resid) 887 size = uio->uio_resid; 888 else 889 size = space; 890 /* 891 * First segment to transfer is minimum of 892 * transfer size and contiguous space in 893 * pipe buffer. If first segment to transfer 894 * is less than the transfer size, we've got 895 * a wraparound in the buffer. 896 */ 897 segsize = wpipe->pipe_buffer.size - 898 wpipe->pipe_buffer.in; 899 if (segsize > size) 900 segsize = size; 901 902 /* Transfer first segment */ 903 904 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 905 segsize, uio); 906 907 if (error == 0 && segsize < size) { 908 /* 909 * Transfer remaining part now, to 910 * support atomic writes. Wraparound 911 * happened. 912 */ 913 if (wpipe->pipe_buffer.in + segsize != 914 wpipe->pipe_buffer.size) 915 panic("Expected pipe buffer wraparound disappeared"); 916 917 error = uiomove(&wpipe->pipe_buffer.buffer[0], 918 size - segsize, uio); 919 } 920 if (error == 0) { 921 wpipe->pipe_buffer.in += size; 922 if (wpipe->pipe_buffer.in >= 923 wpipe->pipe_buffer.size) { 924 if (wpipe->pipe_buffer.in != size - segsize + wpipe->pipe_buffer.size) 925 panic("Expected wraparound bad"); 926 wpipe->pipe_buffer.in = size - segsize; 927 } 928 929 wpipe->pipe_buffer.cnt += size; 930 if (wpipe->pipe_buffer.cnt > wpipe->pipe_buffer.size) 931 panic("Pipe buffer overflow"); 932 933 } 934 pipeunlock(wpipe); 935 } 936 if (error) 937 break; 938 939 } else { 940 /* 941 * If the "read-side" has been blocked, wake it up now. 942 */ 943 if (wpipe->pipe_state & PIPE_WANTR) { 944 wpipe->pipe_state &= ~PIPE_WANTR; 945 wakeup(wpipe); 946 } 947 948 /* 949 * don't block on non-blocking I/O 950 */ 951 if (fp->f_flag & FNONBLOCK) { 952 error = EAGAIN; 953 break; 954 } 955 956 /* 957 * We have no more space and have something to offer, 958 * wake up select/poll. 959 */ 960 pipeselwakeup(wpipe); 961 962 wpipe->pipe_state |= PIPE_WANTW; 963 error = tsleep(wpipe, PRIBIO | PCATCH, "pipewr", 0); 964 if (error != 0) 965 break; 966 /* 967 * If read side wants to go away, we just issue a signal 968 * to ourselves. 969 */ 970 if (wpipe->pipe_state & PIPE_EOF) { 971 error = EPIPE; 972 break; 973 } 974 } 975 } 976 977 --wpipe->pipe_busy; 978 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 979 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 980 wakeup(wpipe); 981 } else if (wpipe->pipe_buffer.cnt > 0) { 982 /* 983 * If we have put any characters in the buffer, we wake up 984 * the reader. 985 */ 986 if (wpipe->pipe_state & PIPE_WANTR) { 987 wpipe->pipe_state &= ~PIPE_WANTR; 988 wakeup(wpipe); 989 } 990 } 991 992 /* 993 * Don't return EPIPE if I/O was successful 994 */ 995 if ((wpipe->pipe_buffer.cnt == 0) && 996 (uio->uio_resid == 0) && 997 (error == EPIPE)) 998 error = 0; 999 1000 if (error == 0) 1001 vfs_timestamp(&wpipe->pipe_mtime); 1002 1003 /* 1004 * We have something to offer, 1005 * wake up select/poll. 1006 */ 1007 if (wpipe->pipe_buffer.cnt) 1008 pipeselwakeup(wpipe); 1009 1010 return (error); 1011} 1012 1013/* 1014 * we implement a very minimal set of ioctls for compatibility with sockets. 1015 */ 1016int 1017pipe_ioctl(fp, cmd, data, p) 1018 struct file *fp; 1019 u_long cmd; 1020 caddr_t data; 1021 struct proc *p; 1022{ 1023 struct pipe *mpipe = (struct pipe *)fp->f_data; 1024 1025 switch (cmd) { 1026 1027 case FIONBIO: 1028 return (0); 1029 1030 case FIOASYNC: 1031 if (*(int *)data) { 1032 mpipe->pipe_state |= PIPE_ASYNC; 1033 } else { 1034 mpipe->pipe_state &= ~PIPE_ASYNC; 1035 } 1036 return (0); 1037 1038 case FIONREAD: 1039 if (mpipe->pipe_state & PIPE_DIRECTW) 1040 *(int *)data = mpipe->pipe_map.cnt; 1041 else 1042 *(int *)data = mpipe->pipe_buffer.cnt; 1043 return (0); 1044 1045 case FIOSETOWN: 1046 return (fsetown(*(int *)data, &mpipe->pipe_sigio)); 1047 1048 case FIOGETOWN: 1049 *(int *)data = fgetown(mpipe->pipe_sigio); 1050 return (0); 1051 1052 /* This is deprecated, FIOSETOWN should be used instead. */ 1053 case TIOCSPGRP: 1054 return (fsetown(-(*(int *)data), &mpipe->pipe_sigio)); 1055 1056 /* This is deprecated, FIOGETOWN should be used instead. */ 1057 case TIOCGPGRP: 1058 *(int *)data = -fgetown(mpipe->pipe_sigio); 1059 return (0); 1060 1061 } 1062 return (ENOTTY); 1063} 1064 1065int 1066pipe_poll(fp, events, cred, p) 1067 struct file *fp; 1068 int events; 1069 struct ucred *cred; 1070 struct proc *p; 1071{ 1072 struct pipe *rpipe = (struct pipe *)fp->f_data; 1073 struct pipe *wpipe; 1074 int revents = 0; 1075 1076 wpipe = rpipe->pipe_peer; 1077 if (events & (POLLIN | POLLRDNORM)) 1078 if ((rpipe->pipe_state & PIPE_DIRECTW) || 1079 (rpipe->pipe_buffer.cnt > 0) || 1080 (rpipe->pipe_state & PIPE_EOF)) 1081 revents |= events & (POLLIN | POLLRDNORM); 1082 1083 if (events & (POLLOUT | POLLWRNORM)) 1084 if (wpipe == NULL || (wpipe->pipe_state & PIPE_EOF) || 1085 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) && 1086 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF)) 1087 revents |= events & (POLLOUT | POLLWRNORM); 1088 1089 if ((rpipe->pipe_state & PIPE_EOF) || 1090 (wpipe == NULL) || 1091 (wpipe->pipe_state & PIPE_EOF)) 1092 revents |= POLLHUP; 1093 1094 if (revents == 0) { 1095 if (events & (POLLIN | POLLRDNORM)) { 1096 selrecord(p, &rpipe->pipe_sel); 1097 rpipe->pipe_state |= PIPE_SEL; 1098 } 1099 1100 if (events & (POLLOUT | POLLWRNORM)) { 1101 selrecord(p, &wpipe->pipe_sel); 1102 wpipe->pipe_state |= PIPE_SEL; 1103 } 1104 } 1105 1106 return (revents); 1107} 1108 1109static int 1110pipe_stat(fp, ub, p) 1111 struct file *fp; 1112 struct stat *ub; 1113 struct proc *p; 1114{ 1115 struct pipe *pipe = (struct pipe *)fp->f_data; 1116 1117 bzero((caddr_t)ub, sizeof(*ub)); 1118 ub->st_mode = S_IFIFO; 1119 ub->st_blksize = pipe->pipe_buffer.size; 1120 ub->st_size = pipe->pipe_buffer.cnt; 1121 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize; 1122 ub->st_atimespec = pipe->pipe_atime; 1123 ub->st_mtimespec = pipe->pipe_mtime; 1124 ub->st_ctimespec = pipe->pipe_ctime; 1125 ub->st_uid = fp->f_cred->cr_uid; 1126 ub->st_gid = fp->f_cred->cr_gid; 1127 /* 1128 * Left as 0: st_dev, st_ino, st_nlink, st_rdev, st_flags, st_gen. 1129 * XXX (st_dev, st_ino) should be unique. 1130 */ 1131 return (0); 1132} 1133 1134/* ARGSUSED */ 1135static int 1136pipe_close(fp, p) 1137 struct file *fp; 1138 struct proc *p; 1139{ 1140 struct pipe *cpipe = (struct pipe *)fp->f_data; 1141 1142 fp->f_ops = &badfileops; 1143 fp->f_data = NULL; 1144 funsetown(cpipe->pipe_sigio); 1145 pipeclose(cpipe); 1146 return (0); 1147} 1148 1149static void 1150pipe_free_kmem(cpipe) 1151 struct pipe *cpipe; 1152{ 1153 1154 if (cpipe->pipe_buffer.buffer != NULL) { 1155 if (cpipe->pipe_buffer.size > PIPE_SIZE) 1156 --nbigpipe; 1157 amountpipekva -= cpipe->pipe_buffer.size; 1158 kmem_free(kernel_map, 1159 (vm_offset_t)cpipe->pipe_buffer.buffer, 1160 cpipe->pipe_buffer.size); 1161 cpipe->pipe_buffer.buffer = NULL; 1162 } 1163#ifndef PIPE_NODIRECT 1164 if (cpipe->pipe_map.kva != NULL) { 1165 amountpipekva -= cpipe->pipe_buffer.size + PAGE_SIZE; 1166 kmem_free(kernel_map, 1167 cpipe->pipe_map.kva, 1168 cpipe->pipe_buffer.size + PAGE_SIZE); 1169 cpipe->pipe_map.cnt = 0; 1170 cpipe->pipe_map.kva = 0; 1171 cpipe->pipe_map.pos = 0; 1172 cpipe->pipe_map.npages = 0; 1173 } 1174#endif 1175} 1176 1177/* 1178 * shutdown the pipe 1179 */ 1180static void 1181pipeclose(cpipe) 1182 struct pipe *cpipe; 1183{ 1184 struct pipe *ppipe; 1185 1186 if (cpipe) { 1187 1188 pipeselwakeup(cpipe); 1189 1190 /* 1191 * If the other side is blocked, wake it up saying that 1192 * we want to close it down. 1193 */ 1194 while (cpipe->pipe_busy) { 1195 wakeup(cpipe); 1196 cpipe->pipe_state |= PIPE_WANT | PIPE_EOF; 1197 tsleep(cpipe, PRIBIO, "pipecl", 0); 1198 } 1199 1200 /* 1201 * Disconnect from peer 1202 */ 1203 if ((ppipe = cpipe->pipe_peer) != NULL) { 1204 pipeselwakeup(ppipe); 1205 1206 ppipe->pipe_state |= PIPE_EOF; 1207 wakeup(ppipe); 1208 ppipe->pipe_peer = NULL; 1209 } 1210 /* 1211 * free resources 1212 */ 1213 mtx_lock(&vm_mtx); 1214 pipe_free_kmem(cpipe); 1215 zfree(pipe_zone, cpipe); 1216 mtx_unlock(&vm_mtx); 1217 } 1218} 1219 1220/*ARGSUSED*/ 1221static int 1222pipe_kqfilter(struct file *fp, struct knote *kn) 1223{ 1224 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; 1225 1226 switch (kn->kn_filter) { 1227 case EVFILT_READ: 1228 kn->kn_fop = &pipe_rfiltops; 1229 break; 1230 case EVFILT_WRITE: 1231 kn->kn_fop = &pipe_wfiltops; 1232 break; 1233 default: 1234 return (1); 1235 } 1236 1237 SLIST_INSERT_HEAD(&rpipe->pipe_sel.si_note, kn, kn_selnext); 1238 return (0); 1239} 1240 1241static void 1242filt_pipedetach(struct knote *kn) 1243{ 1244 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; 1245 1246 SLIST_REMOVE(&rpipe->pipe_sel.si_note, kn, knote, kn_selnext); 1247} 1248 1249/*ARGSUSED*/ 1250static int 1251filt_piperead(struct knote *kn, long hint) 1252{ 1253 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; 1254 struct pipe *wpipe = rpipe->pipe_peer; 1255 1256 kn->kn_data = rpipe->pipe_buffer.cnt; 1257 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) 1258 kn->kn_data = rpipe->pipe_map.cnt; 1259 1260 if ((rpipe->pipe_state & PIPE_EOF) || 1261 (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { 1262 kn->kn_flags |= EV_EOF; 1263 return (1); 1264 } 1265 return (kn->kn_data > 0); 1266} 1267 1268/*ARGSUSED*/ 1269static int 1270filt_pipewrite(struct knote *kn, long hint) 1271{ 1272 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; 1273 struct pipe *wpipe = rpipe->pipe_peer; 1274 1275 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { 1276 kn->kn_data = 0; 1277 kn->kn_flags |= EV_EOF; 1278 return (1); 1279 } 1280 kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1281 if (wpipe->pipe_state & PIPE_DIRECTW) 1282 kn->kn_data = 0; 1283 1284 return (kn->kn_data >= PIPE_BUF); 1285} 1286