The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]

FreeBSD/Linux Kernel Cross Reference
sys/kern/sys_pipe.c

Version: -  FREEBSD  -  FREEBSD-13-STABLE  -  FREEBSD-13-0  -  FREEBSD-12-STABLE  -  FREEBSD-12-0  -  FREEBSD-11-STABLE  -  FREEBSD-11-0  -  FREEBSD-10-STABLE  -  FREEBSD-10-0  -  FREEBSD-9-STABLE  -  FREEBSD-9-0  -  FREEBSD-8-STABLE  -  FREEBSD-8-0  -  FREEBSD-7-STABLE  -  FREEBSD-7-0  -  FREEBSD-6-STABLE  -  FREEBSD-6-0  -  FREEBSD-5-STABLE  -  FREEBSD-5-0  -  FREEBSD-4-STABLE  -  FREEBSD-3-STABLE  -  FREEBSD22  -  l41  -  OPENBSD  -  linux-2.6  -  MK84  -  PLAN9  -  xnu-8792 
SearchContext: -  none  -  3  -  10 

    1 /*-
    2  * Copyright (c) 1996 John S. Dyson
    3  * Copyright (c) 2012 Giovanni Trematerra
    4  * All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice immediately at the beginning of the file, without modification,
   11  *    this list of conditions, and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  * 3. Absolutely no warranty of function or purpose is made by the author
   16  *    John S. Dyson.
   17  * 4. Modifications may be freely made to this file if the above conditions
   18  *    are met.
   19  */
   20 
   21 /*
   22  * This file contains a high-performance replacement for the socket-based
   23  * pipes scheme originally used in FreeBSD/4.4Lite.  It does not support
   24  * all features of sockets, but does do everything that pipes normally
   25  * do.
   26  */
   27 
   28 /*
   29  * This code has two modes of operation, a small write mode and a large
   30  * write mode.  The small write mode acts like conventional pipes with
   31  * a kernel buffer.  If the buffer is less than PIPE_MINDIRECT, then the
   32  * "normal" pipe buffering is done.  If the buffer is between PIPE_MINDIRECT
   33  * and PIPE_SIZE in size, the sending process pins the underlying pages in
   34  * memory, and the receiving process copies directly from these pinned pages
   35  * in the sending process.
   36  *
   37  * If the sending process receives a signal, it is possible that it will
   38  * go away, and certainly its address space can change, because control
   39  * is returned back to the user-mode side.  In that case, the pipe code
   40  * arranges to copy the buffer supplied by the user process, to a pageable
   41  * kernel buffer, and the receiving process will grab the data from the
   42  * pageable kernel buffer.  Since signals don't happen all that often,
   43  * the copy operation is normally eliminated.
   44  *
   45  * The constant PIPE_MINDIRECT is chosen to make sure that buffering will
   46  * happen for small transfers so that the system will not spend all of
   47  * its time context switching.
   48  *
   49  * In order to limit the resource use of pipes, two sysctls exist:
   50  *
   51  * kern.ipc.maxpipekva - This is a hard limit on the amount of pageable
   52  * address space available to us in pipe_map. This value is normally
   53  * autotuned, but may also be loader tuned.
   54  *
   55  * kern.ipc.pipekva - This read-only sysctl tracks the current amount of
   56  * memory in use by pipes.
   57  *
   58  * Based on how large pipekva is relative to maxpipekva, the following
   59  * will happen:
   60  *
   61  * 0% - 50%:
   62  *     New pipes are given 16K of memory backing, pipes may dynamically
   63  *     grow to as large as 64K where needed.
   64  * 50% - 75%:
   65  *     New pipes are given 4K (or PAGE_SIZE) of memory backing,
   66  *     existing pipes may NOT grow.
   67  * 75% - 100%:
   68  *     New pipes are given 4K (or PAGE_SIZE) of memory backing,
   69  *     existing pipes will be shrunk down to 4K whenever possible.
   70  *
   71  * Resizing may be disabled by setting kern.ipc.piperesizeallowed=0.  If
   72  * that is set,  the only resize that will occur is the 0 -> SMALL_PIPE_SIZE
   73  * resize which MUST occur for reverse-direction pipes when they are
   74  * first used.
   75  *
   76  * Additional information about the current state of pipes may be obtained
   77  * from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail,
   78  * and kern.ipc.piperesizefail.
   79  *
   80  * Locking rules:  There are two locks present here:  A mutex, used via
   81  * PIPE_LOCK, and a flag, used via pipelock().  All locking is done via
   82  * the flag, as mutexes can not persist over uiomove.  The mutex
   83  * exists only to guard access to the flag, and is not in itself a
   84  * locking mechanism.  Also note that there is only a single mutex for
   85  * both directions of a pipe.
   86  *
   87  * As pipelock() may have to sleep before it can acquire the flag, it
   88  * is important to reread all data after a call to pipelock(); everything
   89  * in the structure may have changed.
   90  */
   91 
   92 #include "opt_compat.h"
   93 
   94 #include <sys/cdefs.h>
   95 __FBSDID("$FreeBSD$");
   96 
   97 #include <sys/param.h>
   98 #include <sys/systm.h>
   99 #include <sys/conf.h>
  100 #include <sys/fcntl.h>
  101 #include <sys/file.h>
  102 #include <sys/filedesc.h>
  103 #include <sys/filio.h>
  104 #include <sys/kernel.h>
  105 #include <sys/lock.h>
  106 #include <sys/mutex.h>
  107 #include <sys/ttycom.h>
  108 #include <sys/stat.h>
  109 #include <sys/malloc.h>
  110 #include <sys/poll.h>
  111 #include <sys/selinfo.h>
  112 #include <sys/signalvar.h>
  113 #include <sys/syscallsubr.h>
  114 #include <sys/sysctl.h>
  115 #include <sys/sysproto.h>
  116 #include <sys/pipe.h>
  117 #include <sys/proc.h>
  118 #include <sys/vnode.h>
  119 #include <sys/uio.h>
  120 #include <sys/user.h>
  121 #include <sys/event.h>
  122 
  123 #include <security/mac/mac_framework.h>
  124 
  125 #include <vm/vm.h>
  126 #include <vm/vm_param.h>
  127 #include <vm/vm_object.h>
  128 #include <vm/vm_kern.h>
  129 #include <vm/vm_extern.h>
  130 #include <vm/pmap.h>
  131 #include <vm/vm_map.h>
  132 #include <vm/vm_page.h>
  133 #include <vm/uma.h>
  134 
  135 /*
  136  * Use this define if you want to disable *fancy* VM things.  Expect an
  137  * approx 30% decrease in transfer rate.  This could be useful for
  138  * NetBSD or OpenBSD.
  139  */
  140 /* #define PIPE_NODIRECT */
  141 
  142 #define PIPE_PEER(pipe) \
  143         (((pipe)->pipe_state & PIPE_NAMED) ? (pipe) : ((pipe)->pipe_peer))
  144 
  145 /*
  146  * interfaces to the outside world
  147  */
  148 static fo_rdwr_t        pipe_read;
  149 static fo_rdwr_t        pipe_write;
  150 static fo_truncate_t    pipe_truncate;
  151 static fo_ioctl_t       pipe_ioctl;
  152 static fo_poll_t        pipe_poll;
  153 static fo_kqfilter_t    pipe_kqfilter;
  154 static fo_stat_t        pipe_stat;
  155 static fo_close_t       pipe_close;
  156 static fo_chmod_t       pipe_chmod;
  157 static fo_chown_t       pipe_chown;
  158 static fo_fill_kinfo_t  pipe_fill_kinfo;
  159 
  160 struct fileops pipeops = {
  161         .fo_read = pipe_read,
  162         .fo_write = pipe_write,
  163         .fo_truncate = pipe_truncate,
  164         .fo_ioctl = pipe_ioctl,
  165         .fo_poll = pipe_poll,
  166         .fo_kqfilter = pipe_kqfilter,
  167         .fo_stat = pipe_stat,
  168         .fo_close = pipe_close,
  169         .fo_chmod = pipe_chmod,
  170         .fo_chown = pipe_chown,
  171         .fo_sendfile = invfo_sendfile,
  172         .fo_fill_kinfo = pipe_fill_kinfo,
  173         .fo_flags = DFLAG_PASSABLE
  174 };
  175 
  176 static void     filt_pipedetach(struct knote *kn);
  177 static void     filt_pipedetach_notsup(struct knote *kn);
  178 static int      filt_pipenotsup(struct knote *kn, long hint);
  179 static int      filt_piperead(struct knote *kn, long hint);
  180 static int      filt_pipewrite(struct knote *kn, long hint);
  181 
  182 static struct filterops pipe_nfiltops = {
  183         .f_isfd = 1,
  184         .f_detach = filt_pipedetach_notsup,
  185         .f_event = filt_pipenotsup
  186 };
  187 static struct filterops pipe_rfiltops = {
  188         .f_isfd = 1,
  189         .f_detach = filt_pipedetach,
  190         .f_event = filt_piperead
  191 };
  192 static struct filterops pipe_wfiltops = {
  193         .f_isfd = 1,
  194         .f_detach = filt_pipedetach,
  195         .f_event = filt_pipewrite
  196 };
  197 
  198 /*
  199  * Default pipe buffer size(s), this can be kind-of large now because pipe
  200  * space is pageable.  The pipe code will try to maintain locality of
  201  * reference for performance reasons, so small amounts of outstanding I/O
  202  * will not wipe the cache.
  203  */
  204 #define MINPIPESIZE (PIPE_SIZE/3)
  205 #define MAXPIPESIZE (2*PIPE_SIZE/3)
  206 
  207 static long amountpipekva;
  208 static int pipefragretry;
  209 static int pipeallocfail;
  210 static int piperesizefail;
  211 static int piperesizeallowed = 1;
  212 
  213 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
  214            &maxpipekva, 0, "Pipe KVA limit");
  215 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD,
  216            &amountpipekva, 0, "Pipe KVA usage");
  217 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD,
  218           &pipefragretry, 0, "Pipe allocation retries due to fragmentation");
  219 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD,
  220           &pipeallocfail, 0, "Pipe allocation failures");
  221 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD,
  222           &piperesizefail, 0, "Pipe resize failures");
  223 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW,
  224           &piperesizeallowed, 0, "Pipe resizing allowed");
  225 
  226 static void pipeinit(void *dummy __unused);
  227 static void pipeclose(struct pipe *cpipe);
  228 static void pipe_free_kmem(struct pipe *cpipe);
  229 static void pipe_create(struct pipe *pipe, int backing);
  230 static void pipe_paircreate(struct thread *td, struct pipepair **p_pp);
  231 static __inline int pipelock(struct pipe *cpipe, int catch);
  232 static __inline void pipeunlock(struct pipe *cpipe);
  233 #ifndef PIPE_NODIRECT
  234 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio);
  235 static void pipe_destroy_write_buffer(struct pipe *wpipe);
  236 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio);
  237 static void pipe_clone_write_buffer(struct pipe *wpipe);
  238 #endif
  239 static int pipespace(struct pipe *cpipe, int size);
  240 static int pipespace_new(struct pipe *cpipe, int size);
  241 
  242 static int      pipe_zone_ctor(void *mem, int size, void *arg, int flags);
  243 static int      pipe_zone_init(void *mem, int size, int flags);
  244 static void     pipe_zone_fini(void *mem, int size);
  245 
  246 static uma_zone_t pipe_zone;
  247 static struct unrhdr *pipeino_unr;
  248 static dev_t pipedev_ino;
  249 
  250 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
  251 
  252 static void
  253 pipeinit(void *dummy __unused)
  254 {
  255 
  256         pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair),
  257             pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini,
  258             UMA_ALIGN_PTR, 0);
  259         KASSERT(pipe_zone != NULL, ("pipe_zone not initialized"));
  260         pipeino_unr = new_unrhdr(1, INT32_MAX, NULL);
  261         KASSERT(pipeino_unr != NULL, ("pipe fake inodes not initialized"));
  262         pipedev_ino = devfs_alloc_cdp_inode();
  263         KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized"));
  264 }
  265 
  266 static int
  267 pipe_zone_ctor(void *mem, int size, void *arg, int flags)
  268 {
  269         struct pipepair *pp;
  270         struct pipe *rpipe, *wpipe;
  271 
  272         KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size"));
  273 
  274         pp = (struct pipepair *)mem;
  275 
  276         /*
  277          * We zero both pipe endpoints to make sure all the kmem pointers
  278          * are NULL, flag fields are zero'd, etc.  We timestamp both
  279          * endpoints with the same time.
  280          */
  281         rpipe = &pp->pp_rpipe;
  282         bzero(rpipe, sizeof(*rpipe));
  283         vfs_timestamp(&rpipe->pipe_ctime);
  284         rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime;
  285 
  286         wpipe = &pp->pp_wpipe;
  287         bzero(wpipe, sizeof(*wpipe));
  288         wpipe->pipe_ctime = rpipe->pipe_ctime;
  289         wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime;
  290 
  291         rpipe->pipe_peer = wpipe;
  292         rpipe->pipe_pair = pp;
  293         wpipe->pipe_peer = rpipe;
  294         wpipe->pipe_pair = pp;
  295 
  296         /*
  297          * Mark both endpoints as present; they will later get free'd
  298          * one at a time.  When both are free'd, then the whole pair
  299          * is released.
  300          */
  301         rpipe->pipe_present = PIPE_ACTIVE;
  302         wpipe->pipe_present = PIPE_ACTIVE;
  303 
  304         /*
  305          * Eventually, the MAC Framework may initialize the label
  306          * in ctor or init, but for now we do it elswhere to avoid
  307          * blocking in ctor or init.
  308          */
  309         pp->pp_label = NULL;
  310 
  311         return (0);
  312 }
  313 
  314 static int
  315 pipe_zone_init(void *mem, int size, int flags)
  316 {
  317         struct pipepair *pp;
  318 
  319         KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size"));
  320 
  321         pp = (struct pipepair *)mem;
  322 
  323         mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_NEW);
  324         return (0);
  325 }
  326 
  327 static void
  328 pipe_zone_fini(void *mem, int size)
  329 {
  330         struct pipepair *pp;
  331 
  332         KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size"));
  333 
  334         pp = (struct pipepair *)mem;
  335 
  336         mtx_destroy(&pp->pp_mtx);
  337 }
  338 
  339 static void
  340 pipe_paircreate(struct thread *td, struct pipepair **p_pp)
  341 {
  342         struct pipepair *pp;
  343         struct pipe *rpipe, *wpipe;
  344 
  345         *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK);
  346 #ifdef MAC
  347         /*
  348          * The MAC label is shared between the connected endpoints.  As a
  349          * result mac_pipe_init() and mac_pipe_create() are called once
  350          * for the pair, and not on the endpoints.
  351          */
  352         mac_pipe_init(pp);
  353         mac_pipe_create(td->td_ucred, pp);
  354 #endif
  355         rpipe = &pp->pp_rpipe;
  356         wpipe = &pp->pp_wpipe;
  357 
  358         knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe));
  359         knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe));
  360 
  361         /* Only the forward direction pipe is backed by default */
  362         pipe_create(rpipe, 1);
  363         pipe_create(wpipe, 0);
  364 
  365         rpipe->pipe_state |= PIPE_DIRECTOK;
  366         wpipe->pipe_state |= PIPE_DIRECTOK;
  367 }
  368 
  369 void
  370 pipe_named_ctor(struct pipe **ppipe, struct thread *td)
  371 {
  372         struct pipepair *pp;
  373 
  374         pipe_paircreate(td, &pp);
  375         pp->pp_rpipe.pipe_state |= PIPE_NAMED;
  376         *ppipe = &pp->pp_rpipe;
  377 }
  378 
  379 void
  380 pipe_dtor(struct pipe *dpipe)
  381 {
  382         struct pipe *peer;
  383         ino_t ino;
  384 
  385         ino = dpipe->pipe_ino;
  386         peer = (dpipe->pipe_state & PIPE_NAMED) != 0 ? dpipe->pipe_peer : NULL;
  387         funsetown(&dpipe->pipe_sigio);
  388         pipeclose(dpipe);
  389         if (peer != NULL) {
  390                 funsetown(&peer->pipe_sigio);
  391                 pipeclose(peer);
  392         }
  393         if (ino != 0 && ino != (ino_t)-1)
  394                 free_unr(pipeino_unr, ino);
  395 }
  396 
  397 /*
  398  * The pipe system call for the DTYPE_PIPE type of pipes.  If we fail, let
  399  * the zone pick up the pieces via pipeclose().
  400  */
  401 int
  402 kern_pipe(struct thread *td, int fildes[2], int flags, struct filecaps *fcaps1,
  403     struct filecaps *fcaps2)
  404 {
  405         struct file *rf, *wf;
  406         struct pipe *rpipe, *wpipe;
  407         struct pipepair *pp;
  408         int fd, fflags, error;
  409 
  410         pipe_paircreate(td, &pp);
  411         rpipe = &pp->pp_rpipe;
  412         wpipe = &pp->pp_wpipe;
  413         error = falloc_caps(td, &rf, &fd, flags, fcaps1);
  414         if (error) {
  415                 pipeclose(rpipe);
  416                 pipeclose(wpipe);
  417                 return (error);
  418         }
  419         /* An extra reference on `rf' has been held for us by falloc_caps(). */
  420         fildes[0] = fd;
  421 
  422         fflags = FREAD | FWRITE;
  423         if ((flags & O_NONBLOCK) != 0)
  424                 fflags |= FNONBLOCK;
  425 
  426         /*
  427          * Warning: once we've gotten past allocation of the fd for the
  428          * read-side, we can only drop the read side via fdrop() in order
  429          * to avoid races against processes which manage to dup() the read
  430          * side while we are blocked trying to allocate the write side.
  431          */
  432         finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops);
  433         error = falloc_caps(td, &wf, &fd, flags, fcaps2);
  434         if (error) {
  435                 fdclose(td, rf, fildes[0]);
  436                 fdrop(rf, td);
  437                 /* rpipe has been closed by fdrop(). */
  438                 pipeclose(wpipe);
  439                 return (error);
  440         }
  441         /* An extra reference on `wf' has been held for us by falloc_caps(). */
  442         finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops);
  443         fdrop(wf, td);
  444         fildes[1] = fd;
  445         fdrop(rf, td);
  446 
  447         return (0);
  448 }
  449 
  450 #ifdef COMPAT_FREEBSD10
  451 /* ARGSUSED */
  452 int
  453 freebsd10_pipe(struct thread *td, struct freebsd10_pipe_args *uap __unused)
  454 {
  455         int error;
  456         int fildes[2];
  457 
  458         error = kern_pipe(td, fildes, 0, NULL, NULL);
  459         if (error)
  460                 return (error);
  461 
  462         td->td_retval[0] = fildes[0];
  463         td->td_retval[1] = fildes[1];
  464 
  465         return (0);
  466 }
  467 #endif
  468 
  469 int
  470 sys_pipe2(struct thread *td, struct pipe2_args *uap)
  471 {
  472         int error, fildes[2];
  473 
  474         if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK))
  475                 return (EINVAL);
  476         error = kern_pipe(td, fildes, uap->flags, NULL, NULL);
  477         if (error)
  478                 return (error);
  479         error = copyout(fildes, uap->fildes, 2 * sizeof(int));
  480         if (error) {
  481                 (void)kern_close(td, fildes[0]);
  482                 (void)kern_close(td, fildes[1]);
  483         }
  484         return (error);
  485 }
  486 
  487 /*
  488  * Allocate kva for pipe circular buffer, the space is pageable
  489  * This routine will 'realloc' the size of a pipe safely, if it fails
  490  * it will retain the old buffer.
  491  * If it fails it will return ENOMEM.
  492  */
  493 static int
  494 pipespace_new(cpipe, size)
  495         struct pipe *cpipe;
  496         int size;
  497 {
  498         caddr_t buffer;
  499         int error, cnt, firstseg;
  500         static int curfail = 0;
  501         static struct timeval lastfail;
  502 
  503         KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked"));
  504         KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW),
  505                 ("pipespace: resize of direct writes not allowed"));
  506 retry:
  507         cnt = cpipe->pipe_buffer.cnt;
  508         if (cnt > size)
  509                 size = cnt;
  510 
  511         size = round_page(size);
  512         buffer = (caddr_t) vm_map_min(pipe_map);
  513 
  514         error = vm_map_find(pipe_map, NULL, 0, (vm_offset_t *)&buffer, size, 0,
  515             VMFS_ANY_SPACE, VM_PROT_RW, VM_PROT_RW, 0);
  516         if (error != KERN_SUCCESS) {
  517                 if ((cpipe->pipe_buffer.buffer == NULL) &&
  518                         (size > SMALL_PIPE_SIZE)) {
  519                         size = SMALL_PIPE_SIZE;
  520                         pipefragretry++;
  521                         goto retry;
  522                 }
  523                 if (cpipe->pipe_buffer.buffer == NULL) {
  524                         pipeallocfail++;
  525                         if (ppsratecheck(&lastfail, &curfail, 1))
  526                                 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n");
  527                 } else {
  528                         piperesizefail++;
  529                 }
  530                 return (ENOMEM);
  531         }
  532 
  533         /* copy data, then free old resources if we're resizing */
  534         if (cnt > 0) {
  535                 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) {
  536                         firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out;
  537                         bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
  538                                 buffer, firstseg);
  539                         if ((cnt - firstseg) > 0)
  540                                 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg],
  541                                         cpipe->pipe_buffer.in);
  542                 } else {
  543                         bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
  544                                 buffer, cnt);
  545                 }
  546         }
  547         pipe_free_kmem(cpipe);
  548         cpipe->pipe_buffer.buffer = buffer;
  549         cpipe->pipe_buffer.size = size;
  550         cpipe->pipe_buffer.in = cnt;
  551         cpipe->pipe_buffer.out = 0;
  552         cpipe->pipe_buffer.cnt = cnt;
  553         atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size);
  554         return (0);
  555 }
  556 
  557 /*
  558  * Wrapper for pipespace_new() that performs locking assertions.
  559  */
  560 static int
  561 pipespace(cpipe, size)
  562         struct pipe *cpipe;
  563         int size;
  564 {
  565 
  566         KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
  567                 ("Unlocked pipe passed to pipespace"));
  568         return (pipespace_new(cpipe, size));
  569 }
  570 
  571 /*
  572  * lock a pipe for I/O, blocking other access
  573  */
  574 static __inline int
  575 pipelock(cpipe, catch)
  576         struct pipe *cpipe;
  577         int catch;
  578 {
  579         int error;
  580 
  581         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
  582         while (cpipe->pipe_state & PIPE_LOCKFL) {
  583                 cpipe->pipe_state |= PIPE_LWANT;
  584                 error = msleep(cpipe, PIPE_MTX(cpipe),
  585                     catch ? (PRIBIO | PCATCH) : PRIBIO,
  586                     "pipelk", 0);
  587                 if (error != 0)
  588                         return (error);
  589         }
  590         cpipe->pipe_state |= PIPE_LOCKFL;
  591         return (0);
  592 }
  593 
  594 /*
  595  * unlock a pipe I/O lock
  596  */
  597 static __inline void
  598 pipeunlock(cpipe)
  599         struct pipe *cpipe;
  600 {
  601 
  602         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
  603         KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
  604                 ("Unlocked pipe passed to pipeunlock"));
  605         cpipe->pipe_state &= ~PIPE_LOCKFL;
  606         if (cpipe->pipe_state & PIPE_LWANT) {
  607                 cpipe->pipe_state &= ~PIPE_LWANT;
  608                 wakeup(cpipe);
  609         }
  610 }
  611 
  612 void
  613 pipeselwakeup(cpipe)
  614         struct pipe *cpipe;
  615 {
  616 
  617         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
  618         if (cpipe->pipe_state & PIPE_SEL) {
  619                 selwakeuppri(&cpipe->pipe_sel, PSOCK);
  620                 if (!SEL_WAITING(&cpipe->pipe_sel))
  621                         cpipe->pipe_state &= ~PIPE_SEL;
  622         }
  623         if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
  624                 pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
  625         KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0);
  626 }
  627 
  628 /*
  629  * Initialize and allocate VM and memory for pipe.  The structure
  630  * will start out zero'd from the ctor, so we just manage the kmem.
  631  */
  632 static void
  633 pipe_create(pipe, backing)
  634         struct pipe *pipe;
  635         int backing;
  636 {
  637 
  638         if (backing) {
  639                 /*
  640                  * Note that these functions can fail if pipe map is exhausted
  641                  * (as a result of too many pipes created), but we ignore the
  642                  * error as it is not fatal and could be provoked by
  643                  * unprivileged users. The only consequence is worse performance
  644                  * with given pipe.
  645                  */
  646                 if (amountpipekva > maxpipekva / 2)
  647                         (void)pipespace_new(pipe, SMALL_PIPE_SIZE);
  648                 else
  649                         (void)pipespace_new(pipe, PIPE_SIZE);
  650         }
  651 
  652         pipe->pipe_ino = -1;
  653 }
  654 
  655 /* ARGSUSED */
  656 static int
  657 pipe_read(fp, uio, active_cred, flags, td)
  658         struct file *fp;
  659         struct uio *uio;
  660         struct ucred *active_cred;
  661         struct thread *td;
  662         int flags;
  663 {
  664         struct pipe *rpipe;
  665         int error;
  666         int nread = 0;
  667         int size;
  668 
  669         rpipe = fp->f_data;
  670         PIPE_LOCK(rpipe);
  671         ++rpipe->pipe_busy;
  672         error = pipelock(rpipe, 1);
  673         if (error)
  674                 goto unlocked_error;
  675 
  676 #ifdef MAC
  677         error = mac_pipe_check_read(active_cred, rpipe->pipe_pair);
  678         if (error)
  679                 goto locked_error;
  680 #endif
  681         if (amountpipekva > (3 * maxpipekva) / 4) {
  682                 if (!(rpipe->pipe_state & PIPE_DIRECTW) &&
  683                         (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
  684                         (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
  685                         (piperesizeallowed == 1)) {
  686                         PIPE_UNLOCK(rpipe);
  687                         pipespace(rpipe, SMALL_PIPE_SIZE);
  688                         PIPE_LOCK(rpipe);
  689                 }
  690         }
  691 
  692         while (uio->uio_resid) {
  693                 /*
  694                  * normal pipe buffer receive
  695                  */
  696                 if (rpipe->pipe_buffer.cnt > 0) {
  697                         size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
  698                         if (size > rpipe->pipe_buffer.cnt)
  699                                 size = rpipe->pipe_buffer.cnt;
  700                         if (size > uio->uio_resid)
  701                                 size = uio->uio_resid;
  702 
  703                         PIPE_UNLOCK(rpipe);
  704                         error = uiomove(
  705                             &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
  706                             size, uio);
  707                         PIPE_LOCK(rpipe);
  708                         if (error)
  709                                 break;
  710 
  711                         rpipe->pipe_buffer.out += size;
  712                         if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
  713                                 rpipe->pipe_buffer.out = 0;
  714 
  715                         rpipe->pipe_buffer.cnt -= size;
  716 
  717                         /*
  718                          * If there is no more to read in the pipe, reset
  719                          * its pointers to the beginning.  This improves
  720                          * cache hit stats.
  721                          */
  722                         if (rpipe->pipe_buffer.cnt == 0) {
  723                                 rpipe->pipe_buffer.in = 0;
  724                                 rpipe->pipe_buffer.out = 0;
  725                         }
  726                         nread += size;
  727 #ifndef PIPE_NODIRECT
  728                 /*
  729                  * Direct copy, bypassing a kernel buffer.
  730                  */
  731                 } else if ((size = rpipe->pipe_map.cnt) &&
  732                            (rpipe->pipe_state & PIPE_DIRECTW)) {
  733                         if (size > uio->uio_resid)
  734                                 size = (u_int) uio->uio_resid;
  735 
  736                         PIPE_UNLOCK(rpipe);
  737                         error = uiomove_fromphys(rpipe->pipe_map.ms,
  738                             rpipe->pipe_map.pos, size, uio);
  739                         PIPE_LOCK(rpipe);
  740                         if (error)
  741                                 break;
  742                         nread += size;
  743                         rpipe->pipe_map.pos += size;
  744                         rpipe->pipe_map.cnt -= size;
  745                         if (rpipe->pipe_map.cnt == 0) {
  746                                 rpipe->pipe_state &= ~PIPE_WANTW;
  747                                 wakeup(rpipe);
  748                         }
  749 #endif
  750                 } else {
  751                         /*
  752                          * detect EOF condition
  753                          * read returns 0 on EOF, no need to set error
  754                          */
  755                         if (rpipe->pipe_state & PIPE_EOF)
  756                                 break;
  757 
  758                         /*
  759                          * If the "write-side" has been blocked, wake it up now.
  760                          */
  761                         if (rpipe->pipe_state & PIPE_WANTW) {
  762                                 rpipe->pipe_state &= ~PIPE_WANTW;
  763                                 wakeup(rpipe);
  764                         }
  765 
  766                         /*
  767                          * Break if some data was read.
  768                          */
  769                         if (nread > 0)
  770                                 break;
  771 
  772                         /*
  773                          * Unlock the pipe buffer for our remaining processing.
  774                          * We will either break out with an error or we will
  775                          * sleep and relock to loop.
  776                          */
  777                         pipeunlock(rpipe);
  778 
  779                         /*
  780                          * Handle non-blocking mode operation or
  781                          * wait for more data.
  782                          */
  783                         if (fp->f_flag & FNONBLOCK) {
  784                                 error = EAGAIN;
  785                         } else {
  786                                 rpipe->pipe_state |= PIPE_WANTR;
  787                                 if ((error = msleep(rpipe, PIPE_MTX(rpipe),
  788                                     PRIBIO | PCATCH,
  789                                     "piperd", 0)) == 0)
  790                                         error = pipelock(rpipe, 1);
  791                         }
  792                         if (error)
  793                                 goto unlocked_error;
  794                 }
  795         }
  796 #ifdef MAC
  797 locked_error:
  798 #endif
  799         pipeunlock(rpipe);
  800 
  801         /* XXX: should probably do this before getting any locks. */
  802         if (error == 0)
  803                 vfs_timestamp(&rpipe->pipe_atime);
  804 unlocked_error:
  805         --rpipe->pipe_busy;
  806 
  807         /*
  808          * PIPE_WANT processing only makes sense if pipe_busy is 0.
  809          */
  810         if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
  811                 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
  812                 wakeup(rpipe);
  813         } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
  814                 /*
  815                  * Handle write blocking hysteresis.
  816                  */
  817                 if (rpipe->pipe_state & PIPE_WANTW) {
  818                         rpipe->pipe_state &= ~PIPE_WANTW;
  819                         wakeup(rpipe);
  820                 }
  821         }
  822 
  823         if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
  824                 pipeselwakeup(rpipe);
  825 
  826         PIPE_UNLOCK(rpipe);
  827         return (error);
  828 }
  829 
  830 #ifndef PIPE_NODIRECT
  831 /*
  832  * Map the sending processes' buffer into kernel space and wire it.
  833  * This is similar to a physical write operation.
  834  */
  835 static int
  836 pipe_build_write_buffer(wpipe, uio)
  837         struct pipe *wpipe;
  838         struct uio *uio;
  839 {
  840         u_int size;
  841         int i;
  842 
  843         PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED);
  844         KASSERT(wpipe->pipe_state & PIPE_DIRECTW,
  845                 ("Clone attempt on non-direct write pipe!"));
  846 
  847         if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size)
  848                 size = wpipe->pipe_buffer.size;
  849         else
  850                 size = uio->uio_iov->iov_len;
  851 
  852         if ((i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
  853             (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ,
  854             wpipe->pipe_map.ms, PIPENPAGES)) < 0)
  855                 return (EFAULT);
  856 
  857 /*
  858  * set up the control block
  859  */
  860         wpipe->pipe_map.npages = i;
  861         wpipe->pipe_map.pos =
  862             ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK;
  863         wpipe->pipe_map.cnt = size;
  864 
  865 /*
  866  * and update the uio data
  867  */
  868 
  869         uio->uio_iov->iov_len -= size;
  870         uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size;
  871         if (uio->uio_iov->iov_len == 0)
  872                 uio->uio_iov++;
  873         uio->uio_resid -= size;
  874         uio->uio_offset += size;
  875         return (0);
  876 }
  877 
  878 /*
  879  * Unwire the process buffer.
  880  */
  881 static void
  882 pipe_destroy_write_buffer(wpipe)
  883         struct pipe *wpipe;
  884 {
  885 
  886         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
  887         KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0,
  888             ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe));
  889 
  890         wpipe->pipe_state &= ~PIPE_DIRECTW;
  891         vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages);
  892         wpipe->pipe_map.npages = 0;
  893 }
  894 
  895 /*
  896  * In the case of a signal, the writing process might go away.  This
  897  * code copies the data into the circular buffer so that the source
  898  * pages can be freed without loss of data.
  899  */
  900 static void
  901 pipe_clone_write_buffer(wpipe)
  902         struct pipe *wpipe;
  903 {
  904         struct uio uio;
  905         struct iovec iov;
  906         int size;
  907         int pos;
  908 
  909         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
  910         KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0,
  911             ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe));
  912 
  913         size = wpipe->pipe_map.cnt;
  914         pos = wpipe->pipe_map.pos;
  915 
  916         wpipe->pipe_buffer.in = size;
  917         wpipe->pipe_buffer.out = 0;
  918         wpipe->pipe_buffer.cnt = size;
  919 
  920         PIPE_UNLOCK(wpipe);
  921         iov.iov_base = wpipe->pipe_buffer.buffer;
  922         iov.iov_len = size;
  923         uio.uio_iov = &iov;
  924         uio.uio_iovcnt = 1;
  925         uio.uio_offset = 0;
  926         uio.uio_resid = size;
  927         uio.uio_segflg = UIO_SYSSPACE;
  928         uio.uio_rw = UIO_READ;
  929         uio.uio_td = curthread;
  930         uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio);
  931         PIPE_LOCK(wpipe);
  932         pipe_destroy_write_buffer(wpipe);
  933 }
  934 
  935 /*
  936  * This implements the pipe buffer write mechanism.  Note that only
  937  * a direct write OR a normal pipe write can be pending at any given time.
  938  * If there are any characters in the pipe buffer, the direct write will
  939  * be deferred until the receiving process grabs all of the bytes from
  940  * the pipe buffer.  Then the direct mapping write is set-up.
  941  */
  942 static int
  943 pipe_direct_write(wpipe, uio)
  944         struct pipe *wpipe;
  945         struct uio *uio;
  946 {
  947         int error;
  948 
  949 retry:
  950         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
  951         error = pipelock(wpipe, 1);
  952         if (error != 0)
  953                 goto error1;
  954         if ((wpipe->pipe_state & PIPE_EOF) != 0) {
  955                 error = EPIPE;
  956                 pipeunlock(wpipe);
  957                 goto error1;
  958         }
  959         if (wpipe->pipe_state & PIPE_DIRECTW) {
  960                 if (wpipe->pipe_state & PIPE_WANTR) {
  961                         wpipe->pipe_state &= ~PIPE_WANTR;
  962                         wakeup(wpipe);
  963                 }
  964                 pipeselwakeup(wpipe);
  965                 wpipe->pipe_state |= PIPE_WANTW;
  966                 pipeunlock(wpipe);
  967                 error = msleep(wpipe, PIPE_MTX(wpipe),
  968                     PRIBIO | PCATCH, "pipdww", 0);
  969                 if (error)
  970                         goto error1;
  971                 else
  972                         goto retry;
  973         }
  974         wpipe->pipe_map.cnt = 0;        /* transfer not ready yet */
  975         if (wpipe->pipe_buffer.cnt > 0) {
  976                 if (wpipe->pipe_state & PIPE_WANTR) {
  977                         wpipe->pipe_state &= ~PIPE_WANTR;
  978                         wakeup(wpipe);
  979                 }
  980                 pipeselwakeup(wpipe);
  981                 wpipe->pipe_state |= PIPE_WANTW;
  982                 pipeunlock(wpipe);
  983                 error = msleep(wpipe, PIPE_MTX(wpipe),
  984                     PRIBIO | PCATCH, "pipdwc", 0);
  985                 if (error)
  986                         goto error1;
  987                 else
  988                         goto retry;
  989         }
  990 
  991         wpipe->pipe_state |= PIPE_DIRECTW;
  992 
  993         PIPE_UNLOCK(wpipe);
  994         error = pipe_build_write_buffer(wpipe, uio);
  995         PIPE_LOCK(wpipe);
  996         if (error) {
  997                 wpipe->pipe_state &= ~PIPE_DIRECTW;
  998                 pipeunlock(wpipe);
  999                 goto error1;
 1000         }
 1001 
 1002         while (wpipe->pipe_map.cnt != 0) {
 1003                 if (wpipe->pipe_state & PIPE_EOF) {
 1004                         pipe_destroy_write_buffer(wpipe);
 1005                         pipeselwakeup(wpipe);
 1006                         pipeunlock(wpipe);
 1007                         error = EPIPE;
 1008                         goto error1;
 1009                 }
 1010                 if (wpipe->pipe_state & PIPE_WANTR) {
 1011                         wpipe->pipe_state &= ~PIPE_WANTR;
 1012                         wakeup(wpipe);
 1013                 }
 1014                 pipeselwakeup(wpipe);
 1015                 wpipe->pipe_state |= PIPE_WANTW;
 1016                 pipeunlock(wpipe);
 1017                 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
 1018                     "pipdwt", 0);
 1019                 pipelock(wpipe, 0);
 1020                 if (error != 0)
 1021                         break;
 1022         }
 1023 
 1024         if (wpipe->pipe_state & PIPE_EOF)
 1025                 error = EPIPE;
 1026         if (error == EINTR || error == ERESTART)
 1027                 pipe_clone_write_buffer(wpipe);
 1028         else
 1029                 pipe_destroy_write_buffer(wpipe);
 1030         pipeunlock(wpipe);
 1031         KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0,
 1032             ("pipe %p leaked PIPE_DIRECTW", wpipe));
 1033         return (error);
 1034 
 1035 error1:
 1036         wakeup(wpipe);
 1037         return (error);
 1038 }
 1039 #endif
 1040 
 1041 static int
 1042 pipe_write(fp, uio, active_cred, flags, td)
 1043         struct file *fp;
 1044         struct uio *uio;
 1045         struct ucred *active_cred;
 1046         struct thread *td;
 1047         int flags;
 1048 {
 1049         int error = 0;
 1050         int desiredsize;
 1051         ssize_t orig_resid;
 1052         struct pipe *wpipe, *rpipe;
 1053 
 1054         rpipe = fp->f_data;
 1055         wpipe = PIPE_PEER(rpipe);
 1056         PIPE_LOCK(rpipe);
 1057         error = pipelock(wpipe, 1);
 1058         if (error) {
 1059                 PIPE_UNLOCK(rpipe);
 1060                 return (error);
 1061         }
 1062         /*
 1063          * detect loss of pipe read side, issue SIGPIPE if lost.
 1064          */
 1065         if (wpipe->pipe_present != PIPE_ACTIVE ||
 1066             (wpipe->pipe_state & PIPE_EOF)) {
 1067                 pipeunlock(wpipe);
 1068                 PIPE_UNLOCK(rpipe);
 1069                 return (EPIPE);
 1070         }
 1071 #ifdef MAC
 1072         error = mac_pipe_check_write(active_cred, wpipe->pipe_pair);
 1073         if (error) {
 1074                 pipeunlock(wpipe);
 1075                 PIPE_UNLOCK(rpipe);
 1076                 return (error);
 1077         }
 1078 #endif
 1079         ++wpipe->pipe_busy;
 1080 
 1081         /* Choose a larger size if it's advantageous */
 1082         desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size);
 1083         while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) {
 1084                 if (piperesizeallowed != 1)
 1085                         break;
 1086                 if (amountpipekva > maxpipekva / 2)
 1087                         break;
 1088                 if (desiredsize == BIG_PIPE_SIZE)
 1089                         break;
 1090                 desiredsize = desiredsize * 2;
 1091         }
 1092 
 1093         /* Choose a smaller size if we're in a OOM situation */
 1094         if ((amountpipekva > (3 * maxpipekva) / 4) &&
 1095                 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
 1096                 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
 1097                 (piperesizeallowed == 1))
 1098                 desiredsize = SMALL_PIPE_SIZE;
 1099 
 1100         /* Resize if the above determined that a new size was necessary */
 1101         if ((desiredsize != wpipe->pipe_buffer.size) &&
 1102                 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) {
 1103                 PIPE_UNLOCK(wpipe);
 1104                 pipespace(wpipe, desiredsize);
 1105                 PIPE_LOCK(wpipe);
 1106         }
 1107         if (wpipe->pipe_buffer.size == 0) {
 1108                 /*
 1109                  * This can only happen for reverse direction use of pipes
 1110                  * in a complete OOM situation.
 1111                  */
 1112                 error = ENOMEM;
 1113                 --wpipe->pipe_busy;
 1114                 pipeunlock(wpipe);
 1115                 PIPE_UNLOCK(wpipe);
 1116                 return (error);
 1117         }
 1118 
 1119         pipeunlock(wpipe);
 1120 
 1121         orig_resid = uio->uio_resid;
 1122 
 1123         while (uio->uio_resid) {
 1124                 int space;
 1125 
 1126                 pipelock(wpipe, 0);
 1127                 if (wpipe->pipe_state & PIPE_EOF) {
 1128                         pipeunlock(wpipe);
 1129                         error = EPIPE;
 1130                         break;
 1131                 }
 1132 #ifndef PIPE_NODIRECT
 1133                 /*
 1134                  * If the transfer is large, we can gain performance if
 1135                  * we do process-to-process copies directly.
 1136                  * If the write is non-blocking, we don't use the
 1137                  * direct write mechanism.
 1138                  *
 1139                  * The direct write mechanism will detect the reader going
 1140                  * away on us.
 1141                  */
 1142                 if (uio->uio_segflg == UIO_USERSPACE &&
 1143                     uio->uio_iov->iov_len >= PIPE_MINDIRECT &&
 1144                     wpipe->pipe_buffer.size >= PIPE_MINDIRECT &&
 1145                     (fp->f_flag & FNONBLOCK) == 0) {
 1146                         pipeunlock(wpipe);
 1147                         error = pipe_direct_write(wpipe, uio);
 1148                         if (error)
 1149                                 break;
 1150                         continue;
 1151                 }
 1152 #endif
 1153 
 1154                 /*
 1155                  * Pipe buffered writes cannot be coincidental with
 1156                  * direct writes.  We wait until the currently executing
 1157                  * direct write is completed before we start filling the
 1158                  * pipe buffer.  We break out if a signal occurs or the
 1159                  * reader goes away.
 1160                  */
 1161                 if (wpipe->pipe_state & PIPE_DIRECTW) {
 1162                         if (wpipe->pipe_state & PIPE_WANTR) {
 1163                                 wpipe->pipe_state &= ~PIPE_WANTR;
 1164                                 wakeup(wpipe);
 1165                         }
 1166                         pipeselwakeup(wpipe);
 1167                         wpipe->pipe_state |= PIPE_WANTW;
 1168                         pipeunlock(wpipe);
 1169                         error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH,
 1170                             "pipbww", 0);
 1171                         if (error)
 1172                                 break;
 1173                         else
 1174                                 continue;
 1175                 }
 1176 
 1177                 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
 1178 
 1179                 /* Writes of size <= PIPE_BUF must be atomic. */
 1180                 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
 1181                         space = 0;
 1182 
 1183                 if (space > 0) {
 1184                         int size;       /* Transfer size */
 1185                         int segsize;    /* first segment to transfer */
 1186 
 1187                         /*
 1188                          * Transfer size is minimum of uio transfer
 1189                          * and free space in pipe buffer.
 1190                          */
 1191                         if (space > uio->uio_resid)
 1192                                 size = uio->uio_resid;
 1193                         else
 1194                                 size = space;
 1195                         /*
 1196                          * First segment to transfer is minimum of
 1197                          * transfer size and contiguous space in
 1198                          * pipe buffer.  If first segment to transfer
 1199                          * is less than the transfer size, we've got
 1200                          * a wraparound in the buffer.
 1201                          */
 1202                         segsize = wpipe->pipe_buffer.size -
 1203                                 wpipe->pipe_buffer.in;
 1204                         if (segsize > size)
 1205                                 segsize = size;
 1206 
 1207                         /* Transfer first segment */
 1208 
 1209                         PIPE_UNLOCK(rpipe);
 1210                         error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
 1211                                         segsize, uio);
 1212                         PIPE_LOCK(rpipe);
 1213 
 1214                         if (error == 0 && segsize < size) {
 1215                                 KASSERT(wpipe->pipe_buffer.in + segsize ==
 1216                                         wpipe->pipe_buffer.size,
 1217                                         ("Pipe buffer wraparound disappeared"));
 1218                                 /*
 1219                                  * Transfer remaining part now, to
 1220                                  * support atomic writes.  Wraparound
 1221                                  * happened.
 1222                                  */
 1223 
 1224                                 PIPE_UNLOCK(rpipe);
 1225                                 error = uiomove(
 1226                                     &wpipe->pipe_buffer.buffer[0],
 1227                                     size - segsize, uio);
 1228                                 PIPE_LOCK(rpipe);
 1229                         }
 1230                         if (error == 0) {
 1231                                 wpipe->pipe_buffer.in += size;
 1232                                 if (wpipe->pipe_buffer.in >=
 1233                                     wpipe->pipe_buffer.size) {
 1234                                         KASSERT(wpipe->pipe_buffer.in ==
 1235                                                 size - segsize +
 1236                                                 wpipe->pipe_buffer.size,
 1237                                                 ("Expected wraparound bad"));
 1238                                         wpipe->pipe_buffer.in = size - segsize;
 1239                                 }
 1240 
 1241                                 wpipe->pipe_buffer.cnt += size;
 1242                                 KASSERT(wpipe->pipe_buffer.cnt <=
 1243                                         wpipe->pipe_buffer.size,
 1244                                         ("Pipe buffer overflow"));
 1245                         }
 1246                         pipeunlock(wpipe);
 1247                         if (error != 0)
 1248                                 break;
 1249                 } else {
 1250                         /*
 1251                          * If the "read-side" has been blocked, wake it up now.
 1252                          */
 1253                         if (wpipe->pipe_state & PIPE_WANTR) {
 1254                                 wpipe->pipe_state &= ~PIPE_WANTR;
 1255                                 wakeup(wpipe);
 1256                         }
 1257 
 1258                         /*
 1259                          * don't block on non-blocking I/O
 1260                          */
 1261                         if (fp->f_flag & FNONBLOCK) {
 1262                                 error = EAGAIN;
 1263                                 pipeunlock(wpipe);
 1264                                 break;
 1265                         }
 1266 
 1267                         /*
 1268                          * We have no more space and have something to offer,
 1269                          * wake up select/poll.
 1270                          */
 1271                         pipeselwakeup(wpipe);
 1272 
 1273                         wpipe->pipe_state |= PIPE_WANTW;
 1274                         pipeunlock(wpipe);
 1275                         error = msleep(wpipe, PIPE_MTX(rpipe),
 1276                             PRIBIO | PCATCH, "pipewr", 0);
 1277                         if (error != 0)
 1278                                 break;
 1279                 }
 1280         }
 1281 
 1282         pipelock(wpipe, 0);
 1283         --wpipe->pipe_busy;
 1284 
 1285         if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
 1286                 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
 1287                 wakeup(wpipe);
 1288         } else if (wpipe->pipe_buffer.cnt > 0) {
 1289                 /*
 1290                  * If we have put any characters in the buffer, we wake up
 1291                  * the reader.
 1292                  */
 1293                 if (wpipe->pipe_state & PIPE_WANTR) {
 1294                         wpipe->pipe_state &= ~PIPE_WANTR;
 1295                         wakeup(wpipe);
 1296                 }
 1297         }
 1298 
 1299         /*
 1300          * Don't return EPIPE if any byte was written.
 1301          * EINTR and other interrupts are handled by generic I/O layer.
 1302          * Do not pretend that I/O succeeded for obvious user error
 1303          * like EFAULT.
 1304          */
 1305         if (uio->uio_resid != orig_resid && error == EPIPE)
 1306                 error = 0;
 1307 
 1308         if (error == 0)
 1309                 vfs_timestamp(&wpipe->pipe_mtime);
 1310 
 1311         /*
 1312          * We have something to offer,
 1313          * wake up select/poll.
 1314          */
 1315         if (wpipe->pipe_buffer.cnt)
 1316                 pipeselwakeup(wpipe);
 1317 
 1318         pipeunlock(wpipe);
 1319         PIPE_UNLOCK(rpipe);
 1320         return (error);
 1321 }
 1322 
 1323 /* ARGSUSED */
 1324 static int
 1325 pipe_truncate(fp, length, active_cred, td)
 1326         struct file *fp;
 1327         off_t length;
 1328         struct ucred *active_cred;
 1329         struct thread *td;
 1330 {
 1331         struct pipe *cpipe;
 1332         int error;
 1333 
 1334         cpipe = fp->f_data;
 1335         if (cpipe->pipe_state & PIPE_NAMED)
 1336                 error = vnops.fo_truncate(fp, length, active_cred, td);
 1337         else
 1338                 error = invfo_truncate(fp, length, active_cred, td);
 1339         return (error);
 1340 }
 1341 
 1342 /*
 1343  * we implement a very minimal set of ioctls for compatibility with sockets.
 1344  */
 1345 static int
 1346 pipe_ioctl(fp, cmd, data, active_cred, td)
 1347         struct file *fp;
 1348         u_long cmd;
 1349         void *data;
 1350         struct ucred *active_cred;
 1351         struct thread *td;
 1352 {
 1353         struct pipe *mpipe = fp->f_data;
 1354         int error;
 1355 
 1356         PIPE_LOCK(mpipe);
 1357 
 1358 #ifdef MAC
 1359         error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data);
 1360         if (error) {
 1361                 PIPE_UNLOCK(mpipe);
 1362                 return (error);
 1363         }
 1364 #endif
 1365 
 1366         error = 0;
 1367         switch (cmd) {
 1368 
 1369         case FIONBIO:
 1370                 break;
 1371 
 1372         case FIOASYNC:
 1373                 if (*(int *)data) {
 1374                         mpipe->pipe_state |= PIPE_ASYNC;
 1375                 } else {
 1376                         mpipe->pipe_state &= ~PIPE_ASYNC;
 1377                 }
 1378                 break;
 1379 
 1380         case FIONREAD:
 1381                 if (!(fp->f_flag & FREAD)) {
 1382                         *(int *)data = 0;
 1383                         PIPE_UNLOCK(mpipe);
 1384                         return (0);
 1385                 }
 1386                 if (mpipe->pipe_state & PIPE_DIRECTW)
 1387                         *(int *)data = mpipe->pipe_map.cnt;
 1388                 else
 1389                         *(int *)data = mpipe->pipe_buffer.cnt;
 1390                 break;
 1391 
 1392         case FIOSETOWN:
 1393                 PIPE_UNLOCK(mpipe);
 1394                 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
 1395                 goto out_unlocked;
 1396 
 1397         case FIOGETOWN:
 1398                 *(int *)data = fgetown(&mpipe->pipe_sigio);
 1399                 break;
 1400 
 1401         /* This is deprecated, FIOSETOWN should be used instead. */
 1402         case TIOCSPGRP:
 1403                 PIPE_UNLOCK(mpipe);
 1404                 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
 1405                 goto out_unlocked;
 1406 
 1407         /* This is deprecated, FIOGETOWN should be used instead. */
 1408         case TIOCGPGRP:
 1409                 *(int *)data = -fgetown(&mpipe->pipe_sigio);
 1410                 break;
 1411 
 1412         default:
 1413                 error = ENOTTY;
 1414                 break;
 1415         }
 1416         PIPE_UNLOCK(mpipe);
 1417 out_unlocked:
 1418         return (error);
 1419 }
 1420 
 1421 static int
 1422 pipe_poll(fp, events, active_cred, td)
 1423         struct file *fp;
 1424         int events;
 1425         struct ucred *active_cred;
 1426         struct thread *td;
 1427 {
 1428         struct pipe *rpipe;
 1429         struct pipe *wpipe;
 1430         int levents, revents;
 1431 #ifdef MAC
 1432         int error;
 1433 #endif
 1434 
 1435         revents = 0;
 1436         rpipe = fp->f_data;
 1437         wpipe = PIPE_PEER(rpipe);
 1438         PIPE_LOCK(rpipe);
 1439 #ifdef MAC
 1440         error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair);
 1441         if (error)
 1442                 goto locked_error;
 1443 #endif
 1444         if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM))
 1445                 if ((rpipe->pipe_state & PIPE_DIRECTW) ||
 1446                     (rpipe->pipe_buffer.cnt > 0))
 1447                         revents |= events & (POLLIN | POLLRDNORM);
 1448 
 1449         if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM))
 1450                 if (wpipe->pipe_present != PIPE_ACTIVE ||
 1451                     (wpipe->pipe_state & PIPE_EOF) ||
 1452                     (((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
 1453                      ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF ||
 1454                          wpipe->pipe_buffer.size == 0)))
 1455                         revents |= events & (POLLOUT | POLLWRNORM);
 1456 
 1457         levents = events &
 1458             (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND);
 1459         if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents &&
 1460             fp->f_seqcount == rpipe->pipe_wgen)
 1461                 events |= POLLINIGNEOF;
 1462 
 1463         if ((events & POLLINIGNEOF) == 0) {
 1464                 if (rpipe->pipe_state & PIPE_EOF) {
 1465                         revents |= (events & (POLLIN | POLLRDNORM));
 1466                         if (wpipe->pipe_present != PIPE_ACTIVE ||
 1467                             (wpipe->pipe_state & PIPE_EOF))
 1468                                 revents |= POLLHUP;
 1469                 }
 1470         }
 1471 
 1472         if (revents == 0) {
 1473                 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) {
 1474                         selrecord(td, &rpipe->pipe_sel);
 1475                         if (SEL_WAITING(&rpipe->pipe_sel))
 1476                                 rpipe->pipe_state |= PIPE_SEL;
 1477                 }
 1478 
 1479                 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) {
 1480                         selrecord(td, &wpipe->pipe_sel);
 1481                         if (SEL_WAITING(&wpipe->pipe_sel))
 1482                                 wpipe->pipe_state |= PIPE_SEL;
 1483                 }
 1484         }
 1485 #ifdef MAC
 1486 locked_error:
 1487 #endif
 1488         PIPE_UNLOCK(rpipe);
 1489 
 1490         return (revents);
 1491 }
 1492 
 1493 /*
 1494  * We shouldn't need locks here as we're doing a read and this should
 1495  * be a natural race.
 1496  */
 1497 static int
 1498 pipe_stat(fp, ub, active_cred, td)
 1499         struct file *fp;
 1500         struct stat *ub;
 1501         struct ucred *active_cred;
 1502         struct thread *td;
 1503 {
 1504         struct pipe *pipe;
 1505         int new_unr;
 1506 #ifdef MAC
 1507         int error;
 1508 #endif
 1509 
 1510         pipe = fp->f_data;
 1511         PIPE_LOCK(pipe);
 1512 #ifdef MAC
 1513         error = mac_pipe_check_stat(active_cred, pipe->pipe_pair);
 1514         if (error) {
 1515                 PIPE_UNLOCK(pipe);
 1516                 return (error);
 1517         }
 1518 #endif
 1519 
 1520         /* For named pipes ask the underlying filesystem. */
 1521         if (pipe->pipe_state & PIPE_NAMED) {
 1522                 PIPE_UNLOCK(pipe);
 1523                 return (vnops.fo_stat(fp, ub, active_cred, td));
 1524         }
 1525 
 1526         /*
 1527          * Lazily allocate an inode number for the pipe.  Most pipe
 1528          * users do not call fstat(2) on the pipe, which means that
 1529          * postponing the inode allocation until it is must be
 1530          * returned to userland is useful.  If alloc_unr failed,
 1531          * assign st_ino zero instead of returning an error.
 1532          * Special pipe_ino values:
 1533          *  -1 - not yet initialized;
 1534          *  0  - alloc_unr failed, return 0 as st_ino forever.
 1535          */
 1536         if (pipe->pipe_ino == (ino_t)-1) {
 1537                 new_unr = alloc_unr(pipeino_unr);
 1538                 if (new_unr != -1)
 1539                         pipe->pipe_ino = new_unr;
 1540                 else
 1541                         pipe->pipe_ino = 0;
 1542         }
 1543         PIPE_UNLOCK(pipe);
 1544 
 1545         bzero(ub, sizeof(*ub));
 1546         ub->st_mode = S_IFIFO;
 1547         ub->st_blksize = PAGE_SIZE;
 1548         if (pipe->pipe_state & PIPE_DIRECTW)
 1549                 ub->st_size = pipe->pipe_map.cnt;
 1550         else
 1551                 ub->st_size = pipe->pipe_buffer.cnt;
 1552         ub->st_blocks = howmany(ub->st_size, ub->st_blksize);
 1553         ub->st_atim = pipe->pipe_atime;
 1554         ub->st_mtim = pipe->pipe_mtime;
 1555         ub->st_ctim = pipe->pipe_ctime;
 1556         ub->st_uid = fp->f_cred->cr_uid;
 1557         ub->st_gid = fp->f_cred->cr_gid;
 1558         ub->st_dev = pipedev_ino;
 1559         ub->st_ino = pipe->pipe_ino;
 1560         /*
 1561          * Left as 0: st_nlink, st_rdev, st_flags, st_gen.
 1562          */
 1563         return (0);
 1564 }
 1565 
 1566 /* ARGSUSED */
 1567 static int
 1568 pipe_close(fp, td)
 1569         struct file *fp;
 1570         struct thread *td;
 1571 {
 1572 
 1573         if (fp->f_vnode != NULL) 
 1574                 return vnops.fo_close(fp, td);
 1575         fp->f_ops = &badfileops;
 1576         pipe_dtor(fp->f_data);
 1577         fp->f_data = NULL;
 1578         return (0);
 1579 }
 1580 
 1581 static int
 1582 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td)
 1583 {
 1584         struct pipe *cpipe;
 1585         int error;
 1586 
 1587         cpipe = fp->f_data;
 1588         if (cpipe->pipe_state & PIPE_NAMED)
 1589                 error = vn_chmod(fp, mode, active_cred, td);
 1590         else
 1591                 error = invfo_chmod(fp, mode, active_cred, td);
 1592         return (error);
 1593 }
 1594 
 1595 static int
 1596 pipe_chown(fp, uid, gid, active_cred, td)
 1597         struct file *fp;
 1598         uid_t uid;
 1599         gid_t gid;
 1600         struct ucred *active_cred;
 1601         struct thread *td;
 1602 {
 1603         struct pipe *cpipe;
 1604         int error;
 1605 
 1606         cpipe = fp->f_data;
 1607         if (cpipe->pipe_state & PIPE_NAMED)
 1608                 error = vn_chown(fp, uid, gid, active_cred, td);
 1609         else
 1610                 error = invfo_chown(fp, uid, gid, active_cred, td);
 1611         return (error);
 1612 }
 1613 
 1614 static int
 1615 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
 1616 {
 1617         struct pipe *pi;
 1618 
 1619         if (fp->f_type == DTYPE_FIFO)
 1620                 return (vn_fill_kinfo(fp, kif, fdp));
 1621         kif->kf_type = KF_TYPE_PIPE;
 1622         pi = fp->f_data;
 1623         kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi;
 1624         kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer;
 1625         kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt;
 1626         return (0);
 1627 }
 1628 
 1629 static void
 1630 pipe_free_kmem(cpipe)
 1631         struct pipe *cpipe;
 1632 {
 1633 
 1634         KASSERT(!mtx_owned(PIPE_MTX(cpipe)),
 1635             ("pipe_free_kmem: pipe mutex locked"));
 1636 
 1637         if (cpipe->pipe_buffer.buffer != NULL) {
 1638                 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size);
 1639                 vm_map_remove(pipe_map,
 1640                     (vm_offset_t)cpipe->pipe_buffer.buffer,
 1641                     (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size);
 1642                 cpipe->pipe_buffer.buffer = NULL;
 1643         }
 1644 #ifndef PIPE_NODIRECT
 1645         {
 1646                 cpipe->pipe_map.cnt = 0;
 1647                 cpipe->pipe_map.pos = 0;
 1648                 cpipe->pipe_map.npages = 0;
 1649         }
 1650 #endif
 1651 }
 1652 
 1653 /*
 1654  * shutdown the pipe
 1655  */
 1656 static void
 1657 pipeclose(cpipe)
 1658         struct pipe *cpipe;
 1659 {
 1660         struct pipepair *pp;
 1661         struct pipe *ppipe;
 1662 
 1663         KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL"));
 1664 
 1665         PIPE_LOCK(cpipe);
 1666         pipelock(cpipe, 0);
 1667         pp = cpipe->pipe_pair;
 1668 
 1669         pipeselwakeup(cpipe);
 1670 
 1671         /*
 1672          * If the other side is blocked, wake it up saying that
 1673          * we want to close it down.
 1674          */
 1675         cpipe->pipe_state |= PIPE_EOF;
 1676         while (cpipe->pipe_busy) {
 1677                 wakeup(cpipe);
 1678                 cpipe->pipe_state |= PIPE_WANT;
 1679                 pipeunlock(cpipe);
 1680                 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
 1681                 pipelock(cpipe, 0);
 1682         }
 1683 
 1684 
 1685         /*
 1686          * Disconnect from peer, if any.
 1687          */
 1688         ppipe = cpipe->pipe_peer;
 1689         if (ppipe->pipe_present == PIPE_ACTIVE) {
 1690                 pipeselwakeup(ppipe);
 1691 
 1692                 ppipe->pipe_state |= PIPE_EOF;
 1693                 wakeup(ppipe);
 1694                 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0);
 1695         }
 1696 
 1697         /*
 1698          * Mark this endpoint as free.  Release kmem resources.  We
 1699          * don't mark this endpoint as unused until we've finished
 1700          * doing that, or the pipe might disappear out from under
 1701          * us.
 1702          */
 1703         PIPE_UNLOCK(cpipe);
 1704         pipe_free_kmem(cpipe);
 1705         PIPE_LOCK(cpipe);
 1706         cpipe->pipe_present = PIPE_CLOSING;
 1707         pipeunlock(cpipe);
 1708 
 1709         /*
 1710          * knlist_clear() may sleep dropping the PIPE_MTX. Set the
 1711          * PIPE_FINALIZED, that allows other end to free the
 1712          * pipe_pair, only after the knotes are completely dismantled.
 1713          */
 1714         knlist_clear(&cpipe->pipe_sel.si_note, 1);
 1715         cpipe->pipe_present = PIPE_FINALIZED;
 1716         seldrain(&cpipe->pipe_sel);
 1717         knlist_destroy(&cpipe->pipe_sel.si_note);
 1718 
 1719         /*
 1720          * If both endpoints are now closed, release the memory for the
 1721          * pipe pair.  If not, unlock.
 1722          */
 1723         if (ppipe->pipe_present == PIPE_FINALIZED) {
 1724                 PIPE_UNLOCK(cpipe);
 1725 #ifdef MAC
 1726                 mac_pipe_destroy(pp);
 1727 #endif
 1728                 uma_zfree(pipe_zone, cpipe->pipe_pair);
 1729         } else
 1730                 PIPE_UNLOCK(cpipe);
 1731 }
 1732 
 1733 /*ARGSUSED*/
 1734 static int
 1735 pipe_kqfilter(struct file *fp, struct knote *kn)
 1736 {
 1737         struct pipe *cpipe;
 1738 
 1739         /*
 1740          * If a filter is requested that is not supported by this file
 1741          * descriptor, don't return an error, but also don't ever generate an
 1742          * event.
 1743          */
 1744         if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) {
 1745                 kn->kn_fop = &pipe_nfiltops;
 1746                 return (0);
 1747         }
 1748         if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) {
 1749                 kn->kn_fop = &pipe_nfiltops;
 1750                 return (0);
 1751         }
 1752         cpipe = fp->f_data;
 1753         PIPE_LOCK(cpipe);
 1754         switch (kn->kn_filter) {
 1755         case EVFILT_READ:
 1756                 kn->kn_fop = &pipe_rfiltops;
 1757                 break;
 1758         case EVFILT_WRITE:
 1759                 kn->kn_fop = &pipe_wfiltops;
 1760                 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) {
 1761                         /* other end of pipe has been closed */
 1762                         PIPE_UNLOCK(cpipe);
 1763                         return (EPIPE);
 1764                 }
 1765                 cpipe = PIPE_PEER(cpipe);
 1766                 break;
 1767         default:
 1768                 PIPE_UNLOCK(cpipe);
 1769                 return (EINVAL);
 1770         }
 1771 
 1772         kn->kn_hook = cpipe; 
 1773         knlist_add(&cpipe->pipe_sel.si_note, kn, 1);
 1774         PIPE_UNLOCK(cpipe);
 1775         return (0);
 1776 }
 1777 
 1778 static void
 1779 filt_pipedetach(struct knote *kn)
 1780 {
 1781         struct pipe *cpipe = kn->kn_hook;
 1782 
 1783         PIPE_LOCK(cpipe);
 1784         knlist_remove(&cpipe->pipe_sel.si_note, kn, 1);
 1785         PIPE_UNLOCK(cpipe);
 1786 }
 1787 
 1788 /*ARGSUSED*/
 1789 static int
 1790 filt_piperead(struct knote *kn, long hint)
 1791 {
 1792         struct pipe *rpipe = kn->kn_hook;
 1793         struct pipe *wpipe = rpipe->pipe_peer;
 1794         int ret;
 1795 
 1796         PIPE_LOCK_ASSERT(rpipe, MA_OWNED);
 1797         kn->kn_data = rpipe->pipe_buffer.cnt;
 1798         if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
 1799                 kn->kn_data = rpipe->pipe_map.cnt;
 1800 
 1801         if ((rpipe->pipe_state & PIPE_EOF) ||
 1802             wpipe->pipe_present != PIPE_ACTIVE ||
 1803             (wpipe->pipe_state & PIPE_EOF)) {
 1804                 kn->kn_flags |= EV_EOF;
 1805                 return (1);
 1806         }
 1807         ret = kn->kn_data > 0;
 1808         return ret;
 1809 }
 1810 
 1811 /*ARGSUSED*/
 1812 static int
 1813 filt_pipewrite(struct knote *kn, long hint)
 1814 {
 1815         struct pipe *wpipe;
 1816 
 1817         /*
 1818          * If this end of the pipe is closed, the knote was removed from the
 1819          * knlist and the list lock (i.e., the pipe lock) is therefore not held.
 1820          */
 1821         wpipe = kn->kn_hook;
 1822         if (wpipe->pipe_present != PIPE_ACTIVE ||
 1823             (wpipe->pipe_state & PIPE_EOF)) {
 1824                 kn->kn_data = 0;
 1825                 kn->kn_flags |= EV_EOF;
 1826                 return (1);
 1827         }
 1828         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
 1829         kn->kn_data = (wpipe->pipe_buffer.size > 0) ?
 1830             (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF;
 1831         if (wpipe->pipe_state & PIPE_DIRECTW)
 1832                 kn->kn_data = 0;
 1833 
 1834         return (kn->kn_data >= PIPE_BUF);
 1835 }
 1836 
 1837 static void
 1838 filt_pipedetach_notsup(struct knote *kn)
 1839 {
 1840 
 1841 }
 1842 
 1843 static int
 1844 filt_pipenotsup(struct knote *kn, long hint)
 1845 {
 1846 
 1847         return (0);
 1848 }

Cache object: e66aef02f2cb71413132d01789fb4f80


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]


This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.