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: src/sys/kern/sys_pipe.c,v 1.60.2.13 2002/08/05 15:05:15 des Exp $ 20 * $DragonFly: src/sys/kern/sys_pipe.c,v 1.2 2003/06/17 04:28:41 dillon Exp $ 21 */ 22 23 /* 24 * This file contains a high-performance replacement for the socket-based 25 * pipes scheme originally used in FreeBSD/4.4Lite. It does not support 26 * all features of sockets, but does do everything that pipes normally 27 * do. 28 */ 29 30 /* 31 * This code has two modes of operation, a small write mode and a large 32 * write mode. The small write mode acts like conventional pipes with 33 * a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the 34 * "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT 35 * and PIPE_SIZE in size, it is fully mapped and wired into the kernel, and 36 * the receiving process can copy it directly from the pages in the sending 37 * process. 38 * 39 * If the sending process receives a signal, it is possible that it will 40 * go away, and certainly its address space can change, because control 41 * is returned back to the user-mode side. In that case, the pipe code 42 * arranges to copy the buffer supplied by the user process, to a pageable 43 * kernel buffer, and the receiving process will grab the data from the 44 * pageable kernel buffer. Since signals don't happen all that often, 45 * the copy operation is normally eliminated. 46 * 47 * The constant PIPE_MINDIRECT is chosen to make sure that buffering will 48 * happen for small transfers so that the system will not spend all of 49 * its time context switching. PIPE_SIZE is constrained by the 50 * amount of kernel virtual memory. 51 */ 52 53 #include <sys/param.h> 54 #include <sys/systm.h> 55 #include <sys/proc.h> 56 #include <sys/fcntl.h> 57 #include <sys/file.h> 58 #include <sys/filedesc.h> 59 #include <sys/filio.h> 60 #include <sys/ttycom.h> 61 #include <sys/stat.h> 62 #include <sys/poll.h> 63 #include <sys/select.h> 64 #include <sys/signalvar.h> 65 #include <sys/sysproto.h> 66 #include <sys/pipe.h> 67 #include <sys/vnode.h> 68 #include <sys/uio.h> 69 #include <sys/event.h> 70 71 #include <vm/vm.h> 72 #include <vm/vm_param.h> 73 #include <sys/lock.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 */ 92 static int pipe_read __P((struct file *fp, struct uio *uio, 93 struct ucred *cred, int flags, struct proc *p)); 94 static int pipe_write __P((struct file *fp, struct uio *uio, 95 struct ucred *cred, int flags, struct proc *p)); 96 static int pipe_close __P((struct file *fp, struct proc *p)); 97 static int pipe_poll __P((struct file *fp, int events, struct ucred *cred, 98 struct proc *p)); 99 static int pipe_kqfilter __P((struct file *fp, struct knote *kn)); 100 static int pipe_stat __P((struct file *fp, struct stat *sb, struct proc *p)); 101 static int pipe_ioctl __P((struct file *fp, u_long cmd, caddr_t data, struct proc *p)); 102 103 static struct fileops pipeops = { 104 pipe_read, pipe_write, pipe_ioctl, pipe_poll, pipe_kqfilter, 105 pipe_stat, pipe_close 106 }; 107 108 static void filt_pipedetach(struct knote *kn); 109 static int filt_piperead(struct knote *kn, long hint); 110 static int filt_pipewrite(struct knote *kn, long hint); 111 112 static struct filterops pipe_rfiltops = 113 { 1, NULL, filt_pipedetach, filt_piperead }; 114 static 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 32 143 static int nbigpipe; 144 145 static int amountpipekva; 146 147 static void pipeclose __P((struct pipe *cpipe)); 148 static void pipe_free_kmem __P((struct pipe *cpipe)); 149 static int pipe_create __P((struct pipe **cpipep)); 150 static __inline int pipelock __P((struct pipe *cpipe, int catch)); 151 static __inline void pipeunlock __P((struct pipe *cpipe)); 152 static __inline void pipeselwakeup __P((struct pipe *cpipe)); 153 #ifndef PIPE_NODIRECT 154 static int pipe_build_write_buffer __P((struct pipe *wpipe, struct uio *uio)); 155 static void pipe_destroy_write_buffer __P((struct pipe *wpipe)); 156 static int pipe_direct_write __P((struct pipe *wpipe, struct uio *uio)); 157 static void pipe_clone_write_buffer __P((struct pipe *wpipe)); 158 #endif 159 static int pipespace __P((struct pipe *cpipe, int size)); 160 161 static vm_zone_t pipe_zone; 162 163 /* 164 * The pipe system call for the DTYPE_PIPE type of pipes 165 */ 166 167 /* ARGSUSED */ 168 int 169 pipe(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 */ 242 static int 243 pipespace(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 object = vm_object_allocate(OBJT_DEFAULT, npages); 258 buffer = (caddr_t) vm_map_min(kernel_map); 259 260 /* 261 * Insert the object into the kernel map, and allocate kva for it. 262 * The map entry is, by default, pageable. 263 * XXX -- minor change needed here for NetBSD/OpenBSD VM systems. 264 */ 265 error = vm_map_find(kernel_map, object, 0, 266 (vm_offset_t *) &buffer, size, 1, 267 VM_PROT_ALL, VM_PROT_ALL, 0); 268 269 if (error != KERN_SUCCESS) { 270 vm_object_deallocate(object); 271 return (ENOMEM); 272 } 273 274 /* free old resources if we're resizing */ 275 pipe_free_kmem(cpipe); 276 cpipe->pipe_buffer.object = object; 277 cpipe->pipe_buffer.buffer = buffer; 278 cpipe->pipe_buffer.size = size; 279 cpipe->pipe_buffer.in = 0; 280 cpipe->pipe_buffer.out = 0; 281 cpipe->pipe_buffer.cnt = 0; 282 amountpipekva += cpipe->pipe_buffer.size; 283 return (0); 284 } 285 286 /* 287 * initialize and allocate VM and memory for pipe 288 */ 289 static int 290 pipe_create(cpipep) 291 struct pipe **cpipep; 292 { 293 struct pipe *cpipe; 294 int error; 295 296 *cpipep = zalloc(pipe_zone); 297 if (*cpipep == NULL) 298 return (ENOMEM); 299 300 cpipe = *cpipep; 301 302 /* so pipespace()->pipe_free_kmem() doesn't follow junk pointer */ 303 cpipe->pipe_buffer.object = NULL; 304 #ifndef PIPE_NODIRECT 305 cpipe->pipe_map.kva = NULL; 306 #endif 307 /* 308 * protect so pipeclose() doesn't follow a junk pointer 309 * if pipespace() fails. 310 */ 311 bzero(&cpipe->pipe_sel, sizeof(cpipe->pipe_sel)); 312 cpipe->pipe_state = 0; 313 cpipe->pipe_peer = NULL; 314 cpipe->pipe_busy = 0; 315 316 #ifndef PIPE_NODIRECT 317 /* 318 * pipe data structure initializations to support direct pipe I/O 319 */ 320 cpipe->pipe_map.cnt = 0; 321 cpipe->pipe_map.kva = 0; 322 cpipe->pipe_map.pos = 0; 323 cpipe->pipe_map.npages = 0; 324 /* cpipe->pipe_map.ms[] = invalid */ 325 #endif 326 327 error = pipespace(cpipe, PIPE_SIZE); 328 if (error) 329 return (error); 330 331 vfs_timestamp(&cpipe->pipe_ctime); 332 cpipe->pipe_atime = cpipe->pipe_ctime; 333 cpipe->pipe_mtime = cpipe->pipe_ctime; 334 335 return (0); 336 } 337 338 339 /* 340 * lock a pipe for I/O, blocking other access 341 */ 342 static __inline int 343 pipelock(cpipe, catch) 344 struct pipe *cpipe; 345 int catch; 346 { 347 int error; 348 349 while (cpipe->pipe_state & PIPE_LOCK) { 350 cpipe->pipe_state |= PIPE_LWANT; 351 error = tsleep(cpipe, catch ? (PRIBIO | PCATCH) : PRIBIO, 352 "pipelk", 0); 353 if (error != 0) 354 return (error); 355 } 356 cpipe->pipe_state |= PIPE_LOCK; 357 return (0); 358 } 359 360 /* 361 * unlock a pipe I/O lock 362 */ 363 static __inline void 364 pipeunlock(cpipe) 365 struct pipe *cpipe; 366 { 367 368 cpipe->pipe_state &= ~PIPE_LOCK; 369 if (cpipe->pipe_state & PIPE_LWANT) { 370 cpipe->pipe_state &= ~PIPE_LWANT; 371 wakeup(cpipe); 372 } 373 } 374 375 static __inline void 376 pipeselwakeup(cpipe) 377 struct pipe *cpipe; 378 { 379 380 if (cpipe->pipe_state & PIPE_SEL) { 381 cpipe->pipe_state &= ~PIPE_SEL; 382 selwakeup(&cpipe->pipe_sel); 383 } 384 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) 385 pgsigio(cpipe->pipe_sigio, SIGIO, 0); 386 KNOTE(&cpipe->pipe_sel.si_note, 0); 387 } 388 389 /* ARGSUSED */ 390 static int 391 pipe_read(fp, uio, cred, flags, p) 392 struct file *fp; 393 struct uio *uio; 394 struct ucred *cred; 395 struct proc *p; 396 int flags; 397 { 398 struct pipe *rpipe = (struct pipe *) fp->f_data; 399 int error; 400 int nread = 0; 401 u_int size; 402 403 ++rpipe->pipe_busy; 404 error = pipelock(rpipe, 1); 405 if (error) 406 goto unlocked_error; 407 408 while (uio->uio_resid) { 409 /* 410 * normal pipe buffer receive 411 */ 412 if (rpipe->pipe_buffer.cnt > 0) { 413 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 414 if (size > rpipe->pipe_buffer.cnt) 415 size = rpipe->pipe_buffer.cnt; 416 if (size > (u_int) uio->uio_resid) 417 size = (u_int) uio->uio_resid; 418 419 error = uiomove(&rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 420 size, uio); 421 if (error) 422 break; 423 424 rpipe->pipe_buffer.out += size; 425 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 426 rpipe->pipe_buffer.out = 0; 427 428 rpipe->pipe_buffer.cnt -= size; 429 430 /* 431 * If there is no more to read in the pipe, reset 432 * its pointers to the beginning. This improves 433 * cache hit stats. 434 */ 435 if (rpipe->pipe_buffer.cnt == 0) { 436 rpipe->pipe_buffer.in = 0; 437 rpipe->pipe_buffer.out = 0; 438 } 439 nread += size; 440 #ifndef PIPE_NODIRECT 441 /* 442 * Direct copy, bypassing a kernel buffer. 443 */ 444 } else if ((size = rpipe->pipe_map.cnt) && 445 (rpipe->pipe_state & PIPE_DIRECTW)) { 446 caddr_t va; 447 if (size > (u_int) uio->uio_resid) 448 size = (u_int) uio->uio_resid; 449 450 va = (caddr_t) rpipe->pipe_map.kva + 451 rpipe->pipe_map.pos; 452 error = uiomove(va, size, uio); 453 if (error) 454 break; 455 nread += size; 456 rpipe->pipe_map.pos += size; 457 rpipe->pipe_map.cnt -= size; 458 if (rpipe->pipe_map.cnt == 0) { 459 rpipe->pipe_state &= ~PIPE_DIRECTW; 460 wakeup(rpipe); 461 } 462 #endif 463 } else { 464 /* 465 * detect EOF condition 466 * read returns 0 on EOF, no need to set error 467 */ 468 if (rpipe->pipe_state & PIPE_EOF) 469 break; 470 471 /* 472 * If the "write-side" has been blocked, wake it up now. 473 */ 474 if (rpipe->pipe_state & PIPE_WANTW) { 475 rpipe->pipe_state &= ~PIPE_WANTW; 476 wakeup(rpipe); 477 } 478 479 /* 480 * Break if some data was read. 481 */ 482 if (nread > 0) 483 break; 484 485 /* 486 * Unlock the pipe buffer for our remaining processing. We 487 * will either break out with an error or we will sleep and 488 * relock to loop. 489 */ 490 pipeunlock(rpipe); 491 492 /* 493 * Handle non-blocking mode operation or 494 * wait for more data. 495 */ 496 if (fp->f_flag & FNONBLOCK) { 497 error = EAGAIN; 498 } else { 499 rpipe->pipe_state |= PIPE_WANTR; 500 if ((error = tsleep(rpipe, PRIBIO | PCATCH, 501 "piperd", 0)) == 0) 502 error = pipelock(rpipe, 1); 503 } 504 if (error) 505 goto unlocked_error; 506 } 507 } 508 pipeunlock(rpipe); 509 510 if (error == 0) 511 vfs_timestamp(&rpipe->pipe_atime); 512 unlocked_error: 513 --rpipe->pipe_busy; 514 515 /* 516 * PIPE_WANT processing only makes sense if pipe_busy is 0. 517 */ 518 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 519 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 520 wakeup(rpipe); 521 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 522 /* 523 * Handle write blocking hysteresis. 524 */ 525 if (rpipe->pipe_state & PIPE_WANTW) { 526 rpipe->pipe_state &= ~PIPE_WANTW; 527 wakeup(rpipe); 528 } 529 } 530 531 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF) 532 pipeselwakeup(rpipe); 533 534 return (error); 535 } 536 537 #ifndef PIPE_NODIRECT 538 /* 539 * Map the sending processes' buffer into kernel space and wire it. 540 * This is similar to a physical write operation. 541 */ 542 static int 543 pipe_build_write_buffer(wpipe, uio) 544 struct pipe *wpipe; 545 struct uio *uio; 546 { 547 u_int size; 548 int i; 549 vm_offset_t addr, endaddr, paddr; 550 551 size = (u_int) uio->uio_iov->iov_len; 552 if (size > wpipe->pipe_buffer.size) 553 size = wpipe->pipe_buffer.size; 554 555 endaddr = round_page((vm_offset_t)uio->uio_iov->iov_base + size); 556 addr = trunc_page((vm_offset_t)uio->uio_iov->iov_base); 557 for (i = 0; addr < endaddr; addr += PAGE_SIZE, i++) { 558 vm_page_t m; 559 560 if (vm_fault_quick((caddr_t)addr, VM_PROT_READ) < 0 || 561 (paddr = pmap_kextract(addr)) == 0) { 562 int j; 563 564 for (j = 0; j < i; j++) 565 vm_page_unwire(wpipe->pipe_map.ms[j], 1); 566 return (EFAULT); 567 } 568 569 m = PHYS_TO_VM_PAGE(paddr); 570 vm_page_wire(m); 571 wpipe->pipe_map.ms[i] = m; 572 } 573 574 /* 575 * set up the control block 576 */ 577 wpipe->pipe_map.npages = i; 578 wpipe->pipe_map.pos = 579 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 580 wpipe->pipe_map.cnt = size; 581 582 /* 583 * and map the buffer 584 */ 585 if (wpipe->pipe_map.kva == 0) { 586 /* 587 * We need to allocate space for an extra page because the 588 * address range might (will) span pages at times. 589 */ 590 wpipe->pipe_map.kva = kmem_alloc_pageable(kernel_map, 591 wpipe->pipe_buffer.size + PAGE_SIZE); 592 amountpipekva += wpipe->pipe_buffer.size + PAGE_SIZE; 593 } 594 pmap_qenter(wpipe->pipe_map.kva, wpipe->pipe_map.ms, 595 wpipe->pipe_map.npages); 596 597 /* 598 * and update the uio data 599 */ 600 601 uio->uio_iov->iov_len -= size; 602 uio->uio_iov->iov_base += size; 603 if (uio->uio_iov->iov_len == 0) 604 uio->uio_iov++; 605 uio->uio_resid -= size; 606 uio->uio_offset += size; 607 return (0); 608 } 609 610 /* 611 * unmap and unwire the process buffer 612 */ 613 static void 614 pipe_destroy_write_buffer(wpipe) 615 struct pipe *wpipe; 616 { 617 int i; 618 619 if (wpipe->pipe_map.kva) { 620 pmap_qremove(wpipe->pipe_map.kva, wpipe->pipe_map.npages); 621 622 if (amountpipekva > MAXPIPEKVA) { 623 vm_offset_t kva = wpipe->pipe_map.kva; 624 wpipe->pipe_map.kva = 0; 625 kmem_free(kernel_map, kva, 626 wpipe->pipe_buffer.size + PAGE_SIZE); 627 amountpipekva -= wpipe->pipe_buffer.size + PAGE_SIZE; 628 } 629 } 630 for (i = 0; i < wpipe->pipe_map.npages; i++) 631 vm_page_unwire(wpipe->pipe_map.ms[i], 1); 632 wpipe->pipe_map.npages = 0; 633 } 634 635 /* 636 * In the case of a signal, the writing process might go away. This 637 * code copies the data into the circular buffer so that the source 638 * pages can be freed without loss of data. 639 */ 640 static void 641 pipe_clone_write_buffer(wpipe) 642 struct pipe *wpipe; 643 { 644 int size; 645 int pos; 646 647 size = wpipe->pipe_map.cnt; 648 pos = wpipe->pipe_map.pos; 649 bcopy((caddr_t) wpipe->pipe_map.kva + pos, 650 (caddr_t) wpipe->pipe_buffer.buffer, size); 651 652 wpipe->pipe_buffer.in = size; 653 wpipe->pipe_buffer.out = 0; 654 wpipe->pipe_buffer.cnt = size; 655 wpipe->pipe_state &= ~PIPE_DIRECTW; 656 657 pipe_destroy_write_buffer(wpipe); 658 } 659 660 /* 661 * This implements the pipe buffer write mechanism. Note that only 662 * a direct write OR a normal pipe write can be pending at any given time. 663 * If there are any characters in the pipe buffer, the direct write will 664 * be deferred until the receiving process grabs all of the bytes from 665 * the pipe buffer. Then the direct mapping write is set-up. 666 */ 667 static int 668 pipe_direct_write(wpipe, uio) 669 struct pipe *wpipe; 670 struct uio *uio; 671 { 672 int error; 673 674 retry: 675 while (wpipe->pipe_state & PIPE_DIRECTW) { 676 if (wpipe->pipe_state & PIPE_WANTR) { 677 wpipe->pipe_state &= ~PIPE_WANTR; 678 wakeup(wpipe); 679 } 680 wpipe->pipe_state |= PIPE_WANTW; 681 error = tsleep(wpipe, PRIBIO | PCATCH, "pipdww", 0); 682 if (error) 683 goto error1; 684 if (wpipe->pipe_state & PIPE_EOF) { 685 error = EPIPE; 686 goto error1; 687 } 688 } 689 wpipe->pipe_map.cnt = 0; /* transfer not ready yet */ 690 if (wpipe->pipe_buffer.cnt > 0) { 691 if (wpipe->pipe_state & PIPE_WANTR) { 692 wpipe->pipe_state &= ~PIPE_WANTR; 693 wakeup(wpipe); 694 } 695 696 wpipe->pipe_state |= PIPE_WANTW; 697 error = tsleep(wpipe, PRIBIO | PCATCH, "pipdwc", 0); 698 if (error) 699 goto error1; 700 if (wpipe->pipe_state & PIPE_EOF) { 701 error = EPIPE; 702 goto error1; 703 } 704 goto retry; 705 } 706 707 wpipe->pipe_state |= PIPE_DIRECTW; 708 709 error = pipe_build_write_buffer(wpipe, uio); 710 if (error) { 711 wpipe->pipe_state &= ~PIPE_DIRECTW; 712 goto error1; 713 } 714 715 error = 0; 716 while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) { 717 if (wpipe->pipe_state & PIPE_EOF) { 718 pipelock(wpipe, 0); 719 pipe_destroy_write_buffer(wpipe); 720 pipeunlock(wpipe); 721 pipeselwakeup(wpipe); 722 error = EPIPE; 723 goto error1; 724 } 725 if (wpipe->pipe_state & PIPE_WANTR) { 726 wpipe->pipe_state &= ~PIPE_WANTR; 727 wakeup(wpipe); 728 } 729 pipeselwakeup(wpipe); 730 error = tsleep(wpipe, PRIBIO | PCATCH, "pipdwt", 0); 731 } 732 733 pipelock(wpipe,0); 734 if (wpipe->pipe_state & PIPE_DIRECTW) { 735 /* 736 * this bit of trickery substitutes a kernel buffer for 737 * the process that might be going away. 738 */ 739 pipe_clone_write_buffer(wpipe); 740 } else { 741 pipe_destroy_write_buffer(wpipe); 742 } 743 pipeunlock(wpipe); 744 return (error); 745 746 error1: 747 wakeup(wpipe); 748 return (error); 749 } 750 #endif 751 752 static int 753 pipe_write(fp, uio, cred, flags, p) 754 struct file *fp; 755 struct uio *uio; 756 struct ucred *cred; 757 struct proc *p; 758 int flags; 759 { 760 int error = 0; 761 int orig_resid; 762 struct pipe *wpipe, *rpipe; 763 764 rpipe = (struct pipe *) fp->f_data; 765 wpipe = rpipe->pipe_peer; 766 767 /* 768 * detect loss of pipe read side, issue SIGPIPE if lost. 769 */ 770 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { 771 return (EPIPE); 772 } 773 ++wpipe->pipe_busy; 774 775 /* 776 * If it is advantageous to resize the pipe buffer, do 777 * so. 778 */ 779 if ((uio->uio_resid > PIPE_SIZE) && 780 (nbigpipe < LIMITBIGPIPES) && 781 (wpipe->pipe_state & PIPE_DIRECTW) == 0 && 782 (wpipe->pipe_buffer.size <= PIPE_SIZE) && 783 (wpipe->pipe_buffer.cnt == 0)) { 784 785 if ((error = pipelock(wpipe,1)) == 0) { 786 if (pipespace(wpipe, BIG_PIPE_SIZE) == 0) 787 nbigpipe++; 788 pipeunlock(wpipe); 789 } 790 } 791 792 /* 793 * If an early error occured unbusy and return, waking up any pending 794 * readers. 795 */ 796 if (error) { 797 --wpipe->pipe_busy; 798 if ((wpipe->pipe_busy == 0) && 799 (wpipe->pipe_state & PIPE_WANT)) { 800 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 801 wakeup(wpipe); 802 } 803 return(error); 804 } 805 806 KASSERT(wpipe->pipe_buffer.buffer != NULL, ("pipe buffer gone")); 807 808 orig_resid = uio->uio_resid; 809 810 while (uio->uio_resid) { 811 int space; 812 813 #ifndef PIPE_NODIRECT 814 /* 815 * If the transfer is large, we can gain performance if 816 * we do process-to-process copies directly. 817 * If the write is non-blocking, we don't use the 818 * direct write mechanism. 819 * 820 * The direct write mechanism will detect the reader going 821 * away on us. 822 */ 823 if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT) && 824 (fp->f_flag & FNONBLOCK) == 0 && 825 (wpipe->pipe_map.kva || (amountpipekva < LIMITPIPEKVA)) && 826 (uio->uio_iov->iov_len >= PIPE_MINDIRECT)) { 827 error = pipe_direct_write( wpipe, uio); 828 if (error) 829 break; 830 continue; 831 } 832 #endif 833 834 /* 835 * Pipe buffered writes cannot be coincidental with 836 * direct writes. We wait until the currently executing 837 * direct write is completed before we start filling the 838 * pipe buffer. We break out if a signal occurs or the 839 * reader goes away. 840 */ 841 retrywrite: 842 while (wpipe->pipe_state & PIPE_DIRECTW) { 843 if (wpipe->pipe_state & PIPE_WANTR) { 844 wpipe->pipe_state &= ~PIPE_WANTR; 845 wakeup(wpipe); 846 } 847 error = tsleep(wpipe, PRIBIO | PCATCH, "pipbww", 0); 848 if (wpipe->pipe_state & PIPE_EOF) 849 break; 850 if (error) 851 break; 852 } 853 if (wpipe->pipe_state & PIPE_EOF) { 854 error = EPIPE; 855 break; 856 } 857 858 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 859 860 /* Writes of size <= PIPE_BUF must be atomic. */ 861 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 862 space = 0; 863 864 if (space > 0 && (wpipe->pipe_buffer.cnt < PIPE_SIZE)) { 865 if ((error = pipelock(wpipe,1)) == 0) { 866 int size; /* Transfer size */ 867 int segsize; /* first segment to transfer */ 868 869 /* 870 * It is possible for a direct write to 871 * slip in on us... handle it here... 872 */ 873 if (wpipe->pipe_state & PIPE_DIRECTW) { 874 pipeunlock(wpipe); 875 goto retrywrite; 876 } 877 /* 878 * If a process blocked in uiomove, our 879 * value for space might be bad. 880 * 881 * XXX will we be ok if the reader has gone 882 * away here? 883 */ 884 if (space > wpipe->pipe_buffer.size - 885 wpipe->pipe_buffer.cnt) { 886 pipeunlock(wpipe); 887 goto retrywrite; 888 } 889 890 /* 891 * Transfer size is minimum of uio transfer 892 * and free space in pipe buffer. 893 */ 894 if (space > uio->uio_resid) 895 size = uio->uio_resid; 896 else 897 size = space; 898 /* 899 * First segment to transfer is minimum of 900 * transfer size and contiguous space in 901 * pipe buffer. If first segment to transfer 902 * is less than the transfer size, we've got 903 * a wraparound in the buffer. 904 */ 905 segsize = wpipe->pipe_buffer.size - 906 wpipe->pipe_buffer.in; 907 if (segsize > size) 908 segsize = size; 909 910 /* Transfer first segment */ 911 912 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 913 segsize, uio); 914 915 if (error == 0 && segsize < size) { 916 /* 917 * Transfer remaining part now, to 918 * support atomic writes. Wraparound 919 * happened. 920 */ 921 if (wpipe->pipe_buffer.in + segsize != 922 wpipe->pipe_buffer.size) 923 panic("Expected pipe buffer wraparound disappeared"); 924 925 error = uiomove(&wpipe->pipe_buffer.buffer[0], 926 size - segsize, uio); 927 } 928 if (error == 0) { 929 wpipe->pipe_buffer.in += size; 930 if (wpipe->pipe_buffer.in >= 931 wpipe->pipe_buffer.size) { 932 if (wpipe->pipe_buffer.in != size - segsize + wpipe->pipe_buffer.size) 933 panic("Expected wraparound bad"); 934 wpipe->pipe_buffer.in = size - segsize; 935 } 936 937 wpipe->pipe_buffer.cnt += size; 938 if (wpipe->pipe_buffer.cnt > wpipe->pipe_buffer.size) 939 panic("Pipe buffer overflow"); 940 941 } 942 pipeunlock(wpipe); 943 } 944 if (error) 945 break; 946 947 } else { 948 /* 949 * If the "read-side" has been blocked, wake it up now. 950 */ 951 if (wpipe->pipe_state & PIPE_WANTR) { 952 wpipe->pipe_state &= ~PIPE_WANTR; 953 wakeup(wpipe); 954 } 955 956 /* 957 * don't block on non-blocking I/O 958 */ 959 if (fp->f_flag & FNONBLOCK) { 960 error = EAGAIN; 961 break; 962 } 963 964 /* 965 * We have no more space and have something to offer, 966 * wake up select/poll. 967 */ 968 pipeselwakeup(wpipe); 969 970 wpipe->pipe_state |= PIPE_WANTW; 971 error = tsleep(wpipe, PRIBIO | PCATCH, "pipewr", 0); 972 if (error != 0) 973 break; 974 /* 975 * If read side wants to go away, we just issue a signal 976 * to ourselves. 977 */ 978 if (wpipe->pipe_state & PIPE_EOF) { 979 error = EPIPE; 980 break; 981 } 982 } 983 } 984 985 --wpipe->pipe_busy; 986 987 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 988 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 989 wakeup(wpipe); 990 } else if (wpipe->pipe_buffer.cnt > 0) { 991 /* 992 * If we have put any characters in the buffer, we wake up 993 * the reader. 994 */ 995 if (wpipe->pipe_state & PIPE_WANTR) { 996 wpipe->pipe_state &= ~PIPE_WANTR; 997 wakeup(wpipe); 998 } 999 } 1000 1001 /* 1002 * Don't return EPIPE if I/O was successful 1003 */ 1004 if ((wpipe->pipe_buffer.cnt == 0) && 1005 (uio->uio_resid == 0) && 1006 (error == EPIPE)) { 1007 error = 0; 1008 } 1009 1010 if (error == 0) 1011 vfs_timestamp(&wpipe->pipe_mtime); 1012 1013 /* 1014 * We have something to offer, 1015 * wake up select/poll. 1016 */ 1017 if (wpipe->pipe_buffer.cnt) 1018 pipeselwakeup(wpipe); 1019 1020 return (error); 1021 } 1022 1023 /* 1024 * we implement a very minimal set of ioctls for compatibility with sockets. 1025 */ 1026 int 1027 pipe_ioctl(fp, cmd, data, p) 1028 struct file *fp; 1029 u_long cmd; 1030 caddr_t data; 1031 struct proc *p; 1032 { 1033 struct pipe *mpipe = (struct pipe *)fp->f_data; 1034 1035 switch (cmd) { 1036 1037 case FIONBIO: 1038 return (0); 1039 1040 case FIOASYNC: 1041 if (*(int *)data) { 1042 mpipe->pipe_state |= PIPE_ASYNC; 1043 } else { 1044 mpipe->pipe_state &= ~PIPE_ASYNC; 1045 } 1046 return (0); 1047 1048 case FIONREAD: 1049 if (mpipe->pipe_state & PIPE_DIRECTW) 1050 *(int *)data = mpipe->pipe_map.cnt; 1051 else 1052 *(int *)data = mpipe->pipe_buffer.cnt; 1053 return (0); 1054 1055 case FIOSETOWN: 1056 return (fsetown(*(int *)data, &mpipe->pipe_sigio)); 1057 1058 case FIOGETOWN: 1059 *(int *)data = fgetown(mpipe->pipe_sigio); 1060 return (0); 1061 1062 /* This is deprecated, FIOSETOWN should be used instead. */ 1063 case TIOCSPGRP: 1064 return (fsetown(-(*(int *)data), &mpipe->pipe_sigio)); 1065 1066 /* This is deprecated, FIOGETOWN should be used instead. */ 1067 case TIOCGPGRP: 1068 *(int *)data = -fgetown(mpipe->pipe_sigio); 1069 return (0); 1070 1071 } 1072 return (ENOTTY); 1073 } 1074 1075 int 1076 pipe_poll(fp, events, cred, p) 1077 struct file *fp; 1078 int events; 1079 struct ucred *cred; 1080 struct proc *p; 1081 { 1082 struct pipe *rpipe = (struct pipe *)fp->f_data; 1083 struct pipe *wpipe; 1084 int revents = 0; 1085 1086 wpipe = rpipe->pipe_peer; 1087 if (events & (POLLIN | POLLRDNORM)) 1088 if ((rpipe->pipe_state & PIPE_DIRECTW) || 1089 (rpipe->pipe_buffer.cnt > 0) || 1090 (rpipe->pipe_state & PIPE_EOF)) 1091 revents |= events & (POLLIN | POLLRDNORM); 1092 1093 if (events & (POLLOUT | POLLWRNORM)) 1094 if (wpipe == NULL || (wpipe->pipe_state & PIPE_EOF) || 1095 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) && 1096 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF)) 1097 revents |= events & (POLLOUT | POLLWRNORM); 1098 1099 if ((rpipe->pipe_state & PIPE_EOF) || 1100 (wpipe == NULL) || 1101 (wpipe->pipe_state & PIPE_EOF)) 1102 revents |= POLLHUP; 1103 1104 if (revents == 0) { 1105 if (events & (POLLIN | POLLRDNORM)) { 1106 selrecord(p, &rpipe->pipe_sel); 1107 rpipe->pipe_state |= PIPE_SEL; 1108 } 1109 1110 if (events & (POLLOUT | POLLWRNORM)) { 1111 selrecord(p, &wpipe->pipe_sel); 1112 wpipe->pipe_state |= PIPE_SEL; 1113 } 1114 } 1115 1116 return (revents); 1117 } 1118 1119 static int 1120 pipe_stat(fp, ub, p) 1121 struct file *fp; 1122 struct stat *ub; 1123 struct proc *p; 1124 { 1125 struct pipe *pipe = (struct pipe *)fp->f_data; 1126 1127 bzero((caddr_t)ub, sizeof(*ub)); 1128 ub->st_mode = S_IFIFO; 1129 ub->st_blksize = pipe->pipe_buffer.size; 1130 ub->st_size = pipe->pipe_buffer.cnt; 1131 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize; 1132 ub->st_atimespec = pipe->pipe_atime; 1133 ub->st_mtimespec = pipe->pipe_mtime; 1134 ub->st_ctimespec = pipe->pipe_ctime; 1135 /* 1136 * Left as 0: st_dev, st_ino, st_nlink, st_uid, st_gid, st_rdev, 1137 * st_flags, st_gen. 1138 * XXX (st_dev, st_ino) should be unique. 1139 */ 1140 return (0); 1141 } 1142 1143 /* ARGSUSED */ 1144 static int 1145 pipe_close(fp, p) 1146 struct file *fp; 1147 struct proc *p; 1148 { 1149 struct pipe *cpipe = (struct pipe *)fp->f_data; 1150 1151 fp->f_ops = &badfileops; 1152 fp->f_data = NULL; 1153 funsetown(cpipe->pipe_sigio); 1154 pipeclose(cpipe); 1155 return (0); 1156 } 1157 1158 static void 1159 pipe_free_kmem(cpipe) 1160 struct pipe *cpipe; 1161 { 1162 1163 if (cpipe->pipe_buffer.buffer != NULL) { 1164 if (cpipe->pipe_buffer.size > PIPE_SIZE) 1165 --nbigpipe; 1166 amountpipekva -= cpipe->pipe_buffer.size; 1167 kmem_free(kernel_map, 1168 (vm_offset_t)cpipe->pipe_buffer.buffer, 1169 cpipe->pipe_buffer.size); 1170 cpipe->pipe_buffer.buffer = NULL; 1171 } 1172 #ifndef PIPE_NODIRECT 1173 if (cpipe->pipe_map.kva != NULL) { 1174 amountpipekva -= cpipe->pipe_buffer.size + PAGE_SIZE; 1175 kmem_free(kernel_map, 1176 cpipe->pipe_map.kva, 1177 cpipe->pipe_buffer.size + PAGE_SIZE); 1178 cpipe->pipe_map.cnt = 0; 1179 cpipe->pipe_map.kva = 0; 1180 cpipe->pipe_map.pos = 0; 1181 cpipe->pipe_map.npages = 0; 1182 } 1183 #endif 1184 } 1185 1186 /* 1187 * shutdown the pipe 1188 */ 1189 static void 1190 pipeclose(cpipe) 1191 struct pipe *cpipe; 1192 { 1193 struct pipe *ppipe; 1194 1195 if (cpipe) { 1196 1197 pipeselwakeup(cpipe); 1198 1199 /* 1200 * If the other side is blocked, wake it up saying that 1201 * we want to close it down. 1202 */ 1203 while (cpipe->pipe_busy) { 1204 wakeup(cpipe); 1205 cpipe->pipe_state |= PIPE_WANT | PIPE_EOF; 1206 tsleep(cpipe, PRIBIO, "pipecl", 0); 1207 } 1208 1209 /* 1210 * Disconnect from peer 1211 */ 1212 if ((ppipe = cpipe->pipe_peer) != NULL) { 1213 pipeselwakeup(ppipe); 1214 1215 ppipe->pipe_state |= PIPE_EOF; 1216 wakeup(ppipe); 1217 KNOTE(&ppipe->pipe_sel.si_note, 0); 1218 ppipe->pipe_peer = NULL; 1219 } 1220 /* 1221 * free resources 1222 */ 1223 pipe_free_kmem(cpipe); 1224 zfree(pipe_zone, cpipe); 1225 } 1226 } 1227 1228 /*ARGSUSED*/ 1229 static int 1230 pipe_kqfilter(struct file *fp, struct knote *kn) 1231 { 1232 struct pipe *cpipe = (struct pipe *)kn->kn_fp->f_data; 1233 1234 switch (kn->kn_filter) { 1235 case EVFILT_READ: 1236 kn->kn_fop = &pipe_rfiltops; 1237 break; 1238 case EVFILT_WRITE: 1239 kn->kn_fop = &pipe_wfiltops; 1240 cpipe = cpipe->pipe_peer; 1241 if (cpipe == NULL) 1242 /* other end of pipe has been closed */ 1243 return (EBADF); 1244 break; 1245 default: 1246 return (1); 1247 } 1248 kn->kn_hook = (caddr_t)cpipe; 1249 1250 SLIST_INSERT_HEAD(&cpipe->pipe_sel.si_note, kn, kn_selnext); 1251 return (0); 1252 } 1253 1254 static void 1255 filt_pipedetach(struct knote *kn) 1256 { 1257 struct pipe *cpipe = (struct pipe *)kn->kn_hook; 1258 1259 SLIST_REMOVE(&cpipe->pipe_sel.si_note, kn, knote, kn_selnext); 1260 } 1261 1262 /*ARGSUSED*/ 1263 static int 1264 filt_piperead(struct knote *kn, long hint) 1265 { 1266 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; 1267 struct pipe *wpipe = rpipe->pipe_peer; 1268 1269 kn->kn_data = rpipe->pipe_buffer.cnt; 1270 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) 1271 kn->kn_data = rpipe->pipe_map.cnt; 1272 1273 if ((rpipe->pipe_state & PIPE_EOF) || 1274 (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { 1275 kn->kn_flags |= EV_EOF; 1276 return (1); 1277 } 1278 return (kn->kn_data > 0); 1279 } 1280 1281 /*ARGSUSED*/ 1282 static int 1283 filt_pipewrite(struct knote *kn, long hint) 1284 { 1285 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; 1286 struct pipe *wpipe = rpipe->pipe_peer; 1287 1288 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { 1289 kn->kn_data = 0; 1290 kn->kn_flags |= EV_EOF; 1291 return (1); 1292 } 1293 kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1294 if (wpipe->pipe_state & PIPE_DIRECTW) 1295 kn->kn_data = 0; 1296 1297 return (kn->kn_data >= PIPE_BUF); 1298 } 1299