sys/kern/sys_pipe.c

   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 1.12 2003/09/03 14:19:06 hmp 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 #include <sys/file2.h>
  83
  84 /*
  85  * Use this define if you want to disable *fancy* VM things.  Expect an
  86  * approx 30% decrease in transfer rate.  This could be useful for
  87  * NetBSD or OpenBSD.
  88  */
  89 /* #define PIPE_NODIRECT */
  90
  91 /*
  92  * interfaces to the outside world
  93  */
  94 static int pipe_read (struct file *fp, struct uio *uio,
  95                 struct ucred *cred, int flags, struct thread *td);
  96 static int pipe_write (struct file *fp, struct uio *uio,
  97                 struct ucred *cred, int flags, struct thread *td);
  98 static int pipe_close (struct file *fp, struct thread *td);
  99 static int pipe_poll (struct file *fp, int events, struct ucred *cred,
 100                 struct thread *td);
 101 static int pipe_kqfilter (struct file *fp, struct knote *kn);
 102 static int pipe_stat (struct file *fp, struct stat *sb, struct thread *td);
 103 static int pipe_ioctl (struct file *fp, u_long cmd, caddr_t data, struct thread *td);
 104
 105 static struct fileops pipeops = {
 106         NULL,   /* port */
 107         0,      /* autoq */
 108         pipe_read, pipe_write, pipe_ioctl, pipe_poll, pipe_kqfilter,
 109         pipe_stat, pipe_close
 110 };
 111
 112 static void     filt_pipedetach(struct knote *kn);
 113 static int      filt_piperead(struct knote *kn, long hint);
 114 static int      filt_pipewrite(struct knote *kn, long hint);
 115
 116 static struct filterops pipe_rfiltops =
 117         { 1, NULL, filt_pipedetach, filt_piperead };
 118 static struct filterops pipe_wfiltops =
 119         { 1, NULL, filt_pipedetach, filt_pipewrite };
 120
 121
 122 /*
 123  * Default pipe buffer size(s), this can be kind-of large now because pipe
 124  * space is pageable.  The pipe code will try to maintain locality of
 125  * reference for performance reasons, so small amounts of outstanding I/O
 126  * will not wipe the cache.
 127  */
 128 #define MINPIPESIZE (PIPE_SIZE/3)
 129 #define MAXPIPESIZE (2*PIPE_SIZE/3)
 130
 131 /*
 132  * Maximum amount of kva for pipes -- this is kind-of a soft limit, but
 133  * is there so that on large systems, we don't exhaust it.
 134  */
 135 #define MAXPIPEKVA (8*1024*1024)
 136
 137 /*
 138  * Limit for direct transfers, we cannot, of course limit
 139  * the amount of kva for pipes in general though.
 140  */
 141 #define LIMITPIPEKVA (16*1024*1024)
 142
 143 /*
 144  * Limit the number of "big" pipes
 145  */
 146 #define LIMITBIGPIPES   32
 147 static int nbigpipe;
 148
 149 static int amountpipekva;
 150
 151 static void pipeclose (struct pipe *cpipe);
 152 static void pipe_free_kmem (struct pipe *cpipe);
 153 static int pipe_create (struct pipe **cpipep);
 154 static __inline int pipelock (struct pipe *cpipe, int catch);
 155 static __inline void pipeunlock (struct pipe *cpipe);
 156 static __inline void pipeselwakeup (struct pipe *cpipe);
 157 #ifndef PIPE_NODIRECT
 158 static int pipe_build_write_buffer (struct pipe *wpipe, struct uio *uio);
 159 static void pipe_destroy_write_buffer (struct pipe *wpipe);
 160 static int pipe_direct_write (struct pipe *wpipe, struct uio *uio);
 161 static void pipe_clone_write_buffer (struct pipe *wpipe);
 162 #endif
 163 static int pipespace (struct pipe *cpipe, int size);
 164
 165 static vm_zone_t pipe_zone;
 166
 167 /*
 168  * The pipe system call for the DTYPE_PIPE type of pipes
 169  *
 170  * pipe_ARgs(int dummy)
 171  */
 172
 173 /* ARGSUSED */
 174 int
 175 pipe(struct pipe_args *uap)
 176 {
 177         struct thread *td = curthread;
 178         struct proc *p = td->td_proc;
 179         struct filedesc *fdp;
 180         struct file *rf, *wf;
 181         struct pipe *rpipe, *wpipe;
 182         int fd1, fd2, error;
 183
 184         KKASSERT(p);
 185         fdp = p->p_fd;
 186
 187         if (pipe_zone == NULL)
 188                 pipe_zone = zinit("PIPE", sizeof(struct pipe), 0, 0, 4);
 189
 190         rpipe = wpipe = NULL;
 191         if (pipe_create(&rpipe) || pipe_create(&wpipe)) {
 192                 pipeclose(rpipe);
 193                 pipeclose(wpipe);
 194                 return (ENFILE);
 195         }
 196
 197         rpipe->pipe_state |= PIPE_DIRECTOK;
 198         wpipe->pipe_state |= PIPE_DIRECTOK;
 199
 200         error = falloc(p, &rf, &fd1);
 201         if (error) {
 202                 pipeclose(rpipe);
 203                 pipeclose(wpipe);
 204                 return (error);
 205         }
 206         fhold(rf);
 207         uap->sysmsg_fds[0] = fd1;
 208
 209         /*
 210          * Warning: once we've gotten past allocation of the fd for the
 211          * read-side, we can only drop the read side via fdrop() in order
 212          * to avoid races against processes which manage to dup() the read
 213          * side while we are blocked trying to allocate the write side.
 214          */
 215         rf->f_flag = FREAD | FWRITE;
 216         rf->f_type = DTYPE_PIPE;
 217         rf->f_data = (caddr_t)rpipe;
 218         rf->f_ops = &pipeops;
 219         error = falloc(p, &wf, &fd2);
 220         if (error) {
 221                 if (fdp->fd_ofiles[fd1] == rf) {
 222                         fdp->fd_ofiles[fd1] = NULL;
 223                         fdrop(rf, td);
 224                 }
 225                 fdrop(rf, td);
 226                 /* rpipe has been closed by fdrop(). */
 227                 pipeclose(wpipe);
 228                 return (error);
 229         }
 230         wf->f_flag = FREAD | FWRITE;
 231         wf->f_type = DTYPE_PIPE;
 232         wf->f_data = (caddr_t)wpipe;
 233         wf->f_ops = &pipeops;
 234         uap->sysmsg_fds[1] = fd2;
 235
 236         rpipe->pipe_peer = wpipe;
 237         wpipe->pipe_peer = rpipe;
 238         fdrop(rf, td);
 239
 240         return (0);
 241 }
 242
 243 /*
 244  * Allocate kva for pipe circular buffer, the space is pageable
 245  * This routine will 'realloc' the size of a pipe safely, if it fails
 246  * it will retain the old buffer.
 247  * If it fails it will return ENOMEM.
 248  */
 249 static int
 250 pipespace(cpipe, size)
 251         struct pipe *cpipe;
 252         int size;
 253 {
 254         struct vm_object *object;
 255         caddr_t buffer;
 256         int npages, error;
 257
 258         npages = round_page(size)/PAGE_SIZE;
 259         /*
 260          * Create an object, I don't like the idea of paging to/from
 261          * kernel_object.
 262          * XXX -- minor change needed here for NetBSD/OpenBSD VM systems.
 263          */
 264         object = vm_object_allocate(OBJT_DEFAULT, npages);
 265         buffer = (caddr_t) vm_map_min(kernel_map);
 266
 267         /*
 268          * Insert the object into the kernel map, and allocate kva for it.
 269          * The map entry is, by default, pageable.
 270          * XXX -- minor change needed here for NetBSD/OpenBSD VM systems.
 271          */
 272         error = vm_map_find(kernel_map, object, 0,
 273                 (vm_offset_t *) &buffer, size, 1,
 274                 VM_PROT_ALL, VM_PROT_ALL, 0);
 275
 276         if (error != KERN_SUCCESS) {
 277                 vm_object_deallocate(object);
 278                 return (ENOMEM);
 279         }
 280
 281         /* free old resources if we're resizing */
 282         pipe_free_kmem(cpipe);
 283         cpipe->pipe_buffer.object = object;
 284         cpipe->pipe_buffer.buffer = buffer;
 285         cpipe->pipe_buffer.size = size;
 286         cpipe->pipe_buffer.in = 0;
 287         cpipe->pipe_buffer.out = 0;
 288         cpipe->pipe_buffer.cnt = 0;
 289         amountpipekva += cpipe->pipe_buffer.size;
 290         return (0);
 291 }
 292
 293 /*
 294  * initialize and allocate VM and memory for pipe
 295  */
 296 static int
 297 pipe_create(cpipep)
 298         struct pipe **cpipep;
 299 {
 300         struct pipe *cpipe;
 301         int error;
 302
 303         *cpipep = zalloc(pipe_zone);
 304         if (*cpipep == NULL)
 305                 return (ENOMEM);
 306
 307         cpipe = *cpipep;
 308
 309         /* so pipespace()->pipe_free_kmem() doesn't follow junk pointer */
 310         cpipe->pipe_buffer.object = NULL;
 311 #ifndef PIPE_NODIRECT
 312         cpipe->pipe_map.kva = NULL;
 313 #endif
 314         /*
 315          * protect so pipeclose() doesn't follow a junk pointer
 316          * if pipespace() fails.
 317          */
 318         bzero(&cpipe->pipe_sel, sizeof(cpipe->pipe_sel));
 319         cpipe->pipe_state = 0;
 320         cpipe->pipe_peer = NULL;
 321         cpipe->pipe_busy = 0;
 322
 323 #ifndef PIPE_NODIRECT
 324         /*
 325          * pipe data structure initializations to support direct pipe I/O
 326          */
 327         cpipe->pipe_map.cnt = 0;
 328         cpipe->pipe_map.kva = 0;
 329         cpipe->pipe_map.pos = 0;
 330         cpipe->pipe_map.npages = 0;
 331         /* cpipe->pipe_map.ms[] = invalid */
 332 #endif
 333
 334         error = pipespace(cpipe, PIPE_SIZE);
 335         if (error)
 336                 return (error);
 337
 338         vfs_timestamp(&cpipe->pipe_ctime);
 339         cpipe->pipe_atime = cpipe->pipe_ctime;
 340         cpipe->pipe_mtime = cpipe->pipe_ctime;
 341
 342         return (0);
 343 }
 344
 345
 346 /*
 347  * lock a pipe for I/O, blocking other access
 348  */
 349 static __inline int
 350 pipelock(cpipe, catch)
 351         struct pipe *cpipe;
 352         int catch;
 353 {
 354         int error;
 355
 356         while (cpipe->pipe_state & PIPE_LOCK) {
 357                 cpipe->pipe_state |= PIPE_LWANT;
 358                 error = tsleep(cpipe, (catch ? PCATCH : 0), "pipelk", 0);
 359                 if (error != 0)
 360                         return (error);
 361         }
 362         cpipe->pipe_state |= PIPE_LOCK;
 363         return (0);
 364 }
 365
 366 /*
 367  * unlock a pipe I/O lock
 368  */
 369 static __inline void
 370 pipeunlock(cpipe)
 371         struct pipe *cpipe;
 372 {
 373
 374         cpipe->pipe_state &= ~PIPE_LOCK;
 375         if (cpipe->pipe_state & PIPE_LWANT) {
 376                 cpipe->pipe_state &= ~PIPE_LWANT;
 377                 wakeup(cpipe);
 378         }
 379 }
 380
 381 static __inline void
 382 pipeselwakeup(cpipe)
 383         struct pipe *cpipe;
 384 {
 385
 386         if (cpipe->pipe_state & PIPE_SEL) {
 387                 cpipe->pipe_state &= ~PIPE_SEL;
 388                 selwakeup(&cpipe->pipe_sel);
 389         }
 390         if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
 391                 pgsigio(cpipe->pipe_sigio, SIGIO, 0);
 392         KNOTE(&cpipe->pipe_sel.si_note, 0);
 393 }
 394
 395 /* ARGSUSED */
 396 static int
 397 pipe_read(struct file *fp, struct uio *uio, struct ucred *cred,
 398         int flags, struct thread *td)
 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, PCATCH,
 503                                     "piperd", 0)) == 0) {
 504                                         error = pipelock(rpipe, 1);
 505                                 }
 506                         }
 507                         if (error)
 508                                 goto unlocked_error;
 509                 }
 510         }
 511         pipeunlock(rpipe);
 512
 513         if (error == 0)
 514                 vfs_timestamp(&rpipe->pipe_atime);
 515 unlocked_error:
 516         --rpipe->pipe_busy;
 517
 518         /*
 519          * PIPE_WANT processing only makes sense if pipe_busy is 0.
 520          */
 521         if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
 522                 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
 523                 wakeup(rpipe);
 524         } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
 525                 /*
 526                  * Handle write blocking hysteresis.
 527                  */
 528                 if (rpipe->pipe_state & PIPE_WANTW) {
 529                         rpipe->pipe_state &= ~PIPE_WANTW;
 530                         wakeup(rpipe);
 531                 }
 532         }
 533
 534         if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
 535                 pipeselwakeup(rpipe);
 536
 537         return (error);
 538 }
 539
 540 #ifndef PIPE_NODIRECT
 541 /*
 542  * Map the sending processes' buffer into kernel space and wire it.
 543  * This is similar to a physical write operation.
 544  */
 545 static int
 546 pipe_build_write_buffer(wpipe, uio)
 547         struct pipe *wpipe;
 548         struct uio *uio;
 549 {
 550         u_int size;
 551         int i;
 552         vm_offset_t addr, endaddr, paddr;
 553
 554         size = (u_int) uio->uio_iov->iov_len;
 555         if (size > wpipe->pipe_buffer.size)
 556                 size = wpipe->pipe_buffer.size;
 557
 558         endaddr = round_page((vm_offset_t)uio->uio_iov->iov_base + size);
 559         addr = trunc_page((vm_offset_t)uio->uio_iov->iov_base);
 560         for (i = 0; addr < endaddr; addr += PAGE_SIZE, i++) {
 561                 vm_page_t m;
 562
 563                 if (vm_fault_quick((caddr_t)addr, VM_PROT_READ) < 0 ||
 564                     (paddr = pmap_kextract(addr)) == 0) {
 565                         int j;
 566
 567                         for (j = 0; j < i; j++)
 568                                 vm_page_unhold(wpipe->pipe_map.ms[j]);
 569                         return (EFAULT);
 570                 }
 571
 572                 m = PHYS_TO_VM_PAGE(paddr);
 573                 vm_page_hold(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 /*
 601  * and update the uio data
 602  */
 603
 604         uio->uio_iov->iov_len -= size;
 605         uio->uio_iov->iov_base += size;
 606         if (uio->uio_iov->iov_len == 0)
 607                 uio->uio_iov++;
 608         uio->uio_resid -= size;
 609         uio->uio_offset += size;
 610         return (0);
 611 }
 612
 613 /*
 614  * unmap and unwire the process buffer
 615  */
 616 static void
 617 pipe_destroy_write_buffer(wpipe)
 618         struct pipe *wpipe;
 619 {
 620         int i;
 621
 622         if (wpipe->pipe_map.kva) {
 623                 pmap_qremove(wpipe->pipe_map.kva, wpipe->pipe_map.npages);
 624
 625                 if (amountpipekva > MAXPIPEKVA) {
 626                         vm_offset_t kva = wpipe->pipe_map.kva;
 627                         wpipe->pipe_map.kva = 0;
 628                         kmem_free(kernel_map, kva,
 629                                 wpipe->pipe_buffer.size + PAGE_SIZE);
 630                         amountpipekva -= wpipe->pipe_buffer.size + PAGE_SIZE;
 631                 }
 632         }
 633         for (i = 0; i < wpipe->pipe_map.npages; i++)
 634                 vm_page_unhold(wpipe->pipe_map.ms[i]);
 635         wpipe->pipe_map.npages = 0;
 636 }
 637
 638 /*
 639  * In the case of a signal, the writing process might go away.  This
 640  * code copies the data into the circular buffer so that the source
 641  * pages can be freed without loss of data.
 642  */
 643 static void
 644 pipe_clone_write_buffer(wpipe)
 645         struct pipe *wpipe;
 646 {
 647         int size;
 648         int pos;
 649
 650         size = wpipe->pipe_map.cnt;
 651         pos = wpipe->pipe_map.pos;
 652         bcopy((caddr_t) wpipe->pipe_map.kva + pos,
 653             (caddr_t) wpipe->pipe_buffer.buffer, size);
 654
 655         wpipe->pipe_buffer.in = size;
 656         wpipe->pipe_buffer.out = 0;
 657         wpipe->pipe_buffer.cnt = size;
 658         wpipe->pipe_state &= ~PIPE_DIRECTW;
 659
 660         pipe_destroy_write_buffer(wpipe);
 661 }
 662
 663 /*
 664  * This implements the pipe buffer write mechanism.  Note that only
 665  * a direct write OR a normal pipe write can be pending at any given time.
 666  * If there are any characters in the pipe buffer, the direct write will
 667  * be deferred until the receiving process grabs all of the bytes from
 668  * the pipe buffer.  Then the direct mapping write is set-up.
 669  */
 670 static int
 671 pipe_direct_write(wpipe, uio)
 672         struct pipe *wpipe;
 673         struct uio *uio;
 674 {
 675         int error;
 676
 677 retry:
 678         while (wpipe->pipe_state & PIPE_DIRECTW) {
 679                 if (wpipe->pipe_state & PIPE_WANTR) {
 680                         wpipe->pipe_state &= ~PIPE_WANTR;
 681                         wakeup(wpipe);
 682                 }
 683                 wpipe->pipe_state |= PIPE_WANTW;
 684                 error = tsleep(wpipe, PCATCH, "pipdww", 0);
 685                 if (error)
 686                         goto error1;
 687                 if (wpipe->pipe_state & PIPE_EOF) {
 688                         error = EPIPE;
 689                         goto error1;
 690                 }
 691         }
 692         wpipe->pipe_map.cnt = 0;        /* transfer not ready yet */
 693         if (wpipe->pipe_buffer.cnt > 0) {
 694                 if (wpipe->pipe_state & PIPE_WANTR) {
 695                         wpipe->pipe_state &= ~PIPE_WANTR;
 696                         wakeup(wpipe);
 697                 }
 698
 699                 wpipe->pipe_state |= PIPE_WANTW;
 700                 error = tsleep(wpipe, PCATCH, "pipdwc", 0);
 701                 if (error)
 702                         goto error1;
 703                 if (wpipe->pipe_state & PIPE_EOF) {
 704                         error = EPIPE;
 705                         goto error1;
 706                 }
 707                 goto retry;
 708         }
 709
 710         wpipe->pipe_state |= PIPE_DIRECTW;
 711
 712         error = pipe_build_write_buffer(wpipe, uio);
 713         if (error) {
 714                 wpipe->pipe_state &= ~PIPE_DIRECTW;
 715                 goto error1;
 716         }
 717
 718         error = 0;
 719         while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
 720                 if (wpipe->pipe_state & PIPE_EOF) {
 721                         pipelock(wpipe, 0);
 722                         pipe_destroy_write_buffer(wpipe);
 723                         pipeunlock(wpipe);
 724                         pipeselwakeup(wpipe);
 725                         error = EPIPE;
 726                         goto error1;
 727                 }
 728                 if (wpipe->pipe_state & PIPE_WANTR) {
 729                         wpipe->pipe_state &= ~PIPE_WANTR;
 730                         wakeup(wpipe);
 731                 }
 732                 pipeselwakeup(wpipe);
 733                 error = tsleep(wpipe, PCATCH, "pipdwt", 0);
 734         }
 735
 736         pipelock(wpipe,0);
 737         if (wpipe->pipe_state & PIPE_DIRECTW) {
 738                 /*
 739                  * this bit of trickery substitutes a kernel buffer for
 740                  * the process that might be going away.
 741                  */
 742                 pipe_clone_write_buffer(wpipe);
 743         } else {
 744                 pipe_destroy_write_buffer(wpipe);
 745         }
 746         pipeunlock(wpipe);
 747         return (error);
 748
 749 error1:
 750         wakeup(wpipe);
 751         return (error);
 752 }
 753 #endif
 754
 755 static int
 756 pipe_write(struct file *fp, struct uio *uio, struct ucred *cred,
 757         int flags, struct thread *td)
 758 {
 759         int error = 0;
 760         int orig_resid;
 761         struct pipe *wpipe, *rpipe;
 762
 763         rpipe = (struct pipe *) fp->f_data;
 764         wpipe = rpipe->pipe_peer;
 765
 766         /*
 767          * detect loss of pipe read side, issue SIGPIPE if lost.
 768          */
 769         if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
 770                 return (EPIPE);
 771         }
 772         ++wpipe->pipe_busy;
 773
 774         /*
 775          * If it is advantageous to resize the pipe buffer, do
 776          * so.
 777          */
 778         if ((uio->uio_resid > PIPE_SIZE) &&
 779                 (nbigpipe < LIMITBIGPIPES) &&
 780                 (wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
 781                 (wpipe->pipe_buffer.size <= PIPE_SIZE) &&
 782                 (wpipe->pipe_buffer.cnt == 0)) {
 783
 784                 if ((error = pipelock(wpipe,1)) == 0) {
 785                         if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
 786                                 nbigpipe++;
 787                         pipeunlock(wpipe);
 788                 }
 789         }
 790
 791         /*
 792          * If an early error occured unbusy and return, waking up any pending
 793          * readers.
 794          */
 795         if (error) {
 796                 --wpipe->pipe_busy;
 797                 if ((wpipe->pipe_busy == 0) &&
 798                     (wpipe->pipe_state & PIPE_WANT)) {
 799                         wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
 800                         wakeup(wpipe);
 801                 }
 802                 return(error);
 803         }
 804
 805         KASSERT(wpipe->pipe_buffer.buffer != NULL, ("pipe buffer gone"));
 806
 807         orig_resid = uio->uio_resid;
 808
 809         while (uio->uio_resid) {
 810                 int space;
 811
 812 #ifndef PIPE_NODIRECT
 813                 /*
 814                  * If the transfer is large, we can gain performance if
 815                  * we do process-to-process copies directly.
 816                  * If the write is non-blocking, we don't use the
 817                  * direct write mechanism.
 818                  *
 819                  * The direct write mechanism will detect the reader going
 820                  * away on us.
 821                  */
 822                 if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT) &&
 823                     (fp->f_flag & FNONBLOCK) == 0 &&
 824                         (wpipe->pipe_map.kva || (amountpipekva < LIMITPIPEKVA)) &&
 825                         (uio->uio_iov->iov_len >= PIPE_MINDIRECT)) {
 826                         error = pipe_direct_write( wpipe, uio);
 827                         if (error)
 828                                 break;
 829                         continue;
 830                 }
 831 #endif
 832
 833                 /*
 834                  * Pipe buffered writes cannot be coincidental with
 835                  * direct writes.  We wait until the currently executing
 836                  * direct write is completed before we start filling the
 837                  * pipe buffer.  We break out if a signal occurs or the
 838                  * reader goes away.
 839                  */
 840         retrywrite:
 841                 while (wpipe->pipe_state & PIPE_DIRECTW) {
 842                         if (wpipe->pipe_state & PIPE_WANTR) {
 843                                 wpipe->pipe_state &= ~PIPE_WANTR;
 844                                 wakeup(wpipe);
 845                         }
 846                         error = tsleep(wpipe, PCATCH, "pipbww", 0);
 847                         if (wpipe->pipe_state & PIPE_EOF)
 848                                 break;
 849                         if (error)
 850                                 break;
 851                 }
 852                 if (wpipe->pipe_state & PIPE_EOF) {
 853                         error = EPIPE;
 854                         break;
 855                 }
 856
 857                 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
 858
 859                 /* Writes of size <= PIPE_BUF must be atomic. */
 860                 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
 861                         space = 0;
 862
 863                 if (space > 0 && (wpipe->pipe_buffer.cnt < PIPE_SIZE)) {
 864                         if ((error = pipelock(wpipe,1)) == 0) {
 865                                 int size;       /* Transfer size */
 866                                 int segsize;    /* first segment to transfer */
 867
 868                                 /*
 869                                  * It is possible for a direct write to
 870                                  * slip in on us... handle it here...
 871                                  */
 872                                 if (wpipe->pipe_state & PIPE_DIRECTW) {
 873                                         pipeunlock(wpipe);
 874                                         goto retrywrite;
 875                                 }
 876                                 /*
 877                                  * If a process blocked in uiomove, our
 878                                  * value for space might be bad.
 879                                  *
 880                                  * XXX will we be ok if the reader has gone
 881                                  * away here?
 882                                  */
 883                                 if (space > wpipe->pipe_buffer.size -
 884                                     wpipe->pipe_buffer.cnt) {
 885                                         pipeunlock(wpipe);
 886                                         goto retrywrite;
 887                                 }
 888
 889                                 /*
 890                                  * Transfer size is minimum of uio transfer
 891                                  * and free space in pipe buffer.
 892                                  */
 893                                 if (space > uio->uio_resid)
 894                                         size = uio->uio_resid;
 895                                 else
 896                                         size = space;
 897                                 /*
 898                                  * First segment to transfer is minimum of
 899                                  * transfer size and contiguous space in
 900                                  * pipe buffer.  If first segment to transfer
 901                                  * is less than the transfer size, we've got
 902                                  * a wraparound in the buffer.
 903                                  */
 904                                 segsize = wpipe->pipe_buffer.size -
 905                                         wpipe->pipe_buffer.in;
 906                                 if (segsize > size)
 907                                         segsize = size;
 908
 909                                 /* Transfer first segment */
 910
 911                                 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
 912                                                 segsize, uio);
 913
 914                                 if (error == 0 && segsize < size) {
 915                                         /*
 916                                          * Transfer remaining part now, to
 917                                          * support atomic writes.  Wraparound
 918                                          * happened.
 919                                          */
 920                                         if (wpipe->pipe_buffer.in + segsize !=
 921                                             wpipe->pipe_buffer.size)
 922                                                 panic("Expected pipe buffer wraparound disappeared");
 923
 924                                         error = uiomove(&wpipe->pipe_buffer.buffer[0],
 925                                                         size - segsize, uio);
 926                                 }
 927                                 if (error == 0) {
 928                                         wpipe->pipe_buffer.in += size;
 929                                         if (wpipe->pipe_buffer.in >=
 930                                             wpipe->pipe_buffer.size) {
 931                                                 if (wpipe->pipe_buffer.in != size - segsize + wpipe->pipe_buffer.size)
 932                                                         panic("Expected wraparound bad");
 933                                                 wpipe->pipe_buffer.in = size - segsize;
 934                                         }
 935
 936                                         wpipe->pipe_buffer.cnt += size;
 937                                         if (wpipe->pipe_buffer.cnt > wpipe->pipe_buffer.size)
 938                                                 panic("Pipe buffer overflow");
 939
 940                                 }
 941                                 pipeunlock(wpipe);
 942                         }
 943                         if (error)
 944                                 break;
 945
 946                 } else {
 947                         /*
 948                          * If the "read-side" has been blocked, wake it up now.
 949                          */
 950                         if (wpipe->pipe_state & PIPE_WANTR) {
 951                                 wpipe->pipe_state &= ~PIPE_WANTR;
 952                                 wakeup(wpipe);
 953                         }
 954
 955                         /*
 956                          * don't block on non-blocking I/O
 957                          */
 958                         if (fp->f_flag & FNONBLOCK) {
 959                                 error = EAGAIN;
 960                                 break;
 961                         }
 962
 963                         /*
 964                          * We have no more space and have something to offer,
 965                          * wake up select/poll.
 966                          */
 967                         pipeselwakeup(wpipe);
 968
 969                         wpipe->pipe_state |= PIPE_WANTW;
 970                         error = tsleep(wpipe, PCATCH, "pipewr", 0);
 971                         if (error != 0)
 972                                 break;
 973                         /*
 974                          * If read side wants to go away, we just issue a signal
 975                          * to ourselves.
 976                          */
 977                         if (wpipe->pipe_state & PIPE_EOF) {
 978                                 error = EPIPE;
 979                                 break;
 980                         }
 981                 }
 982         }
 983
 984         --wpipe->pipe_busy;
 985
 986         if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
 987                 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
 988                 wakeup(wpipe);
 989         } else if (wpipe->pipe_buffer.cnt > 0) {
 990                 /*
 991                  * If we have put any characters in the buffer, we wake up
 992                  * the reader.
 993                  */
 994                 if (wpipe->pipe_state & PIPE_WANTR) {
 995                         wpipe->pipe_state &= ~PIPE_WANTR;
 996                         wakeup(wpipe);
 997                 }
 998         }
 999
1000         /*
1001          * Don't return EPIPE if I/O was successful
1002          */
1003         if ((wpipe->pipe_buffer.cnt == 0) &&
1004             (uio->uio_resid == 0) &&
1005             (error == EPIPE)) {
1006                 error = 0;
1007         }
1008
1009         if (error == 0)
1010                 vfs_timestamp(&wpipe->pipe_mtime);
1011
1012         /*
1013          * We have something to offer,
1014          * wake up select/poll.
1015          */
1016         if (wpipe->pipe_buffer.cnt)
1017                 pipeselwakeup(wpipe);
1018
1019         return (error);
1020 }
1021
1022 /*
1023  * we implement a very minimal set of ioctls for compatibility with sockets.
1024  */
1025 int
1026 pipe_ioctl(struct file *fp, u_long cmd, caddr_t data, struct thread *td)
1027 {
1028         struct pipe *mpipe = (struct pipe *)fp->f_data;
1029
1030         switch (cmd) {
1031
1032         case FIONBIO:
1033                 return (0);
1034
1035         case FIOASYNC:
1036                 if (*(int *)data) {
1037                         mpipe->pipe_state |= PIPE_ASYNC;
1038                 } else {
1039                         mpipe->pipe_state &= ~PIPE_ASYNC;
1040                 }
1041                 return (0);
1042
1043         case FIONREAD:
1044                 if (mpipe->pipe_state & PIPE_DIRECTW)
1045                         *(int *)data = mpipe->pipe_map.cnt;
1046                 else
1047                         *(int *)data = mpipe->pipe_buffer.cnt;
1048                 return (0);
1049
1050         case FIOSETOWN:
1051                 return (fsetown(*(int *)data, &mpipe->pipe_sigio));
1052
1053         case FIOGETOWN:
1054                 *(int *)data = fgetown(mpipe->pipe_sigio);
1055                 return (0);
1056
1057         /* This is deprecated, FIOSETOWN should be used instead. */
1058         case TIOCSPGRP:
1059                 return (fsetown(-(*(int *)data), &mpipe->pipe_sigio));
1060
1061         /* This is deprecated, FIOGETOWN should be used instead. */
1062         case TIOCGPGRP:
1063                 *(int *)data = -fgetown(mpipe->pipe_sigio);
1064                 return (0);
1065
1066         }
1067         return (ENOTTY);
1068 }
1069
1070 int
1071 pipe_poll(struct file *fp, int events, struct ucred *cred, struct thread *td)
1072 {
1073         struct pipe *rpipe = (struct pipe *)fp->f_data;
1074         struct pipe *wpipe;
1075         int revents = 0;
1076
1077         wpipe = rpipe->pipe_peer;
1078         if (events & (POLLIN | POLLRDNORM))
1079                 if ((rpipe->pipe_state & PIPE_DIRECTW) ||
1080                     (rpipe->pipe_buffer.cnt > 0) ||
1081                     (rpipe->pipe_state & PIPE_EOF))
1082                         revents |= events & (POLLIN | POLLRDNORM);
1083
1084         if (events & (POLLOUT | POLLWRNORM))
1085                 if (wpipe == NULL || (wpipe->pipe_state & PIPE_EOF) ||
1086                     (((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
1087                      (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
1088                         revents |= events & (POLLOUT | POLLWRNORM);
1089
1090         if ((rpipe->pipe_state & PIPE_EOF) ||
1091             (wpipe == NULL) ||
1092             (wpipe->pipe_state & PIPE_EOF))
1093                 revents |= POLLHUP;
1094
1095         if (revents == 0) {
1096                 if (events & (POLLIN | POLLRDNORM)) {
1097                         selrecord(td, &rpipe->pipe_sel);
1098                         rpipe->pipe_state |= PIPE_SEL;
1099                 }
1100
1101                 if (events & (POLLOUT | POLLWRNORM)) {
1102                         selrecord(td, &wpipe->pipe_sel);
1103                         wpipe->pipe_state |= PIPE_SEL;
1104                 }
1105         }
1106
1107         return (revents);
1108 }
1109
1110 static int
1111 pipe_stat(struct file *fp, struct stat *ub, struct thread *td)
1112 {
1113         struct pipe *pipe = (struct pipe *)fp->f_data;
1114
1115         bzero((caddr_t)ub, sizeof(*ub));
1116         ub->st_mode = S_IFIFO;
1117         ub->st_blksize = pipe->pipe_buffer.size;
1118         ub->st_size = pipe->pipe_buffer.cnt;
1119         ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
1120         ub->st_atimespec = pipe->pipe_atime;
1121         ub->st_mtimespec = pipe->pipe_mtime;
1122         ub->st_ctimespec = pipe->pipe_ctime;
1123         /*
1124          * Left as 0: st_dev, st_ino, st_nlink, st_uid, st_gid, st_rdev,
1125          * st_flags, st_gen.
1126          * XXX (st_dev, st_ino) should be unique.
1127          */
1128         return (0);
1129 }
1130
1131 /* ARGSUSED */
1132 static int
1133 pipe_close(struct file *fp, struct thread *td)
1134 {
1135         struct pipe *cpipe = (struct pipe *)fp->f_data;
1136
1137         fp->f_ops = &badfileops;
1138         fp->f_data = NULL;
1139         funsetown(cpipe->pipe_sigio);
1140         pipeclose(cpipe);
1141         return (0);
1142 }
1143
1144 static void
1145 pipe_free_kmem(struct pipe *cpipe)
1146 {
1147
1148         if (cpipe->pipe_buffer.buffer != NULL) {
1149                 if (cpipe->pipe_buffer.size > PIPE_SIZE)
1150                         --nbigpipe;
1151                 amountpipekva -= cpipe->pipe_buffer.size;
1152                 kmem_free(kernel_map,
1153                         (vm_offset_t)cpipe->pipe_buffer.buffer,
1154                         cpipe->pipe_buffer.size);
1155                 cpipe->pipe_buffer.buffer = NULL;
1156         }
1157 #ifndef PIPE_NODIRECT
1158         if (cpipe->pipe_map.kva != NULL) {
1159                 amountpipekva -= cpipe->pipe_buffer.size + PAGE_SIZE;
1160                 kmem_free(kernel_map,
1161                         cpipe->pipe_map.kva,
1162                         cpipe->pipe_buffer.size + PAGE_SIZE);
1163                 cpipe->pipe_map.cnt = 0;
1164                 cpipe->pipe_map.kva = 0;
1165                 cpipe->pipe_map.pos = 0;
1166                 cpipe->pipe_map.npages = 0;
1167         }
1168 #endif
1169 }
1170
1171 /*
1172  * shutdown the pipe
1173  */
1174 static void
1175 pipeclose(struct pipe *cpipe)
1176 {
1177         struct pipe *ppipe;
1178
1179         if (cpipe) {
1180
1181                 pipeselwakeup(cpipe);
1182
1183                 /*
1184                  * If the other side is blocked, wake it up saying that
1185                  * we want to close it down.
1186                  */
1187                 while (cpipe->pipe_busy) {
1188                         wakeup(cpipe);
1189                         cpipe->pipe_state |= PIPE_WANT | PIPE_EOF;
1190                         tsleep(cpipe, 0, "pipecl", 0);
1191                 }
1192
1193                 /*
1194                  * Disconnect from peer
1195                  */
1196                 if ((ppipe = cpipe->pipe_peer) != NULL) {
1197                         pipeselwakeup(ppipe);
1198
1199                         ppipe->pipe_state |= PIPE_EOF;
1200                         wakeup(ppipe);
1201                         KNOTE(&ppipe->pipe_sel.si_note, 0);
1202                         ppipe->pipe_peer = NULL;
1203                 }
1204                 /*
1205                  * free resources
1206                  */
1207                 pipe_free_kmem(cpipe);
1208                 zfree(pipe_zone, cpipe);
1209         }
1210 }
1211
1212 /*ARGSUSED*/
1213 static int
1214 pipe_kqfilter(struct file *fp, struct knote *kn)
1215 {
1216         struct pipe *cpipe = (struct pipe *)kn->kn_fp->f_data;
1217
1218         switch (kn->kn_filter) {
1219         case EVFILT_READ:
1220                 kn->kn_fop = &pipe_rfiltops;
1221                 break;
1222         case EVFILT_WRITE:
1223                 kn->kn_fop = &pipe_wfiltops;
1224                 cpipe = cpipe->pipe_peer;
1225                 if (cpipe == NULL)
1226                         /* other end of pipe has been closed */
1227                         return (EPIPE);
1228                 break;
1229         default:
1230                 return (1);
1231         }
1232         kn->kn_hook = (caddr_t)cpipe;
1233
1234         SLIST_INSERT_HEAD(&cpipe->pipe_sel.si_note, kn, kn_selnext);
1235         return (0);
1236 }
1237
1238 static void
1239 filt_pipedetach(struct knote *kn)
1240 {
1241         struct pipe *cpipe = (struct pipe *)kn->kn_hook;
1242
1243         SLIST_REMOVE(&cpipe->pipe_sel.si_note, kn, knote, kn_selnext);
1244 }
1245
1246 /*ARGSUSED*/
1247 static int
1248 filt_piperead(struct knote *kn, long hint)
1249 {
1250         struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1251         struct pipe *wpipe = rpipe->pipe_peer;
1252
1253         kn->kn_data = rpipe->pipe_buffer.cnt;
1254         if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
1255                 kn->kn_data = rpipe->pipe_map.cnt;
1256
1257         if ((rpipe->pipe_state & PIPE_EOF) ||
1258             (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
1259                 kn->kn_flags |= EV_EOF;
1260                 return (1);
1261         }
1262         return (kn->kn_data > 0);
1263 }
1264
1265 /*ARGSUSED*/
1266 static int
1267 filt_pipewrite(struct knote *kn, long hint)
1268 {
1269         struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1270         struct pipe *wpipe = rpipe->pipe_peer;
1271
1272         if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
1273                 kn->kn_data = 0;
1274                 kn->kn_flags |= EV_EOF;
1275                 return (1);
1276         }
1277         kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1278         if (wpipe->pipe_state & PIPE_DIRECTW)
1279                 kn->kn_data = 0;
1280
1281         return (kn->kn_data >= PIPE_BUF);
1282 }