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 <sys/param.h>
93 #include <sys/systm.h>
94 #include <sys/conf.h>
95 #include <sys/fcntl.h>
96 #include <sys/file.h>
97 #include <sys/filedesc.h>
98 #include <sys/filio.h>
99 #include <sys/kernel.h>
100 #include <sys/lock.h>
101 #include <sys/mutex.h>
102 #include <sys/ttycom.h>
103 #include <sys/stat.h>
104 #include <sys/malloc.h>
105 #include <sys/poll.h>
106 #include <sys/priv.h>
107 #include <sys/selinfo.h>
108 #include <sys/signalvar.h>
109 #include <sys/syscallsubr.h>
110 #include <sys/sysctl.h>
111 #include <sys/sysproto.h>
112 #include <sys/pipe.h>
113 #include <sys/proc.h>
114 #include <sys/vnode.h>
115 #include <sys/uio.h>
116 #include <sys/user.h>
117 #include <sys/event.h>
118
119 #include <security/mac/mac_framework.h>
120
121 #include <vm/vm.h>
122 #include <vm/vm_param.h>
123 #include <vm/vm_object.h>
124 #include <vm/vm_kern.h>
125 #include <vm/vm_extern.h>
126 #include <vm/pmap.h>
127 #include <vm/vm_map.h>
128 #include <vm/vm_page.h>
129 #include <vm/uma.h>
130
131 /*
132 * Use this define if you want to disable *fancy* VM things. Expect an
133 * approx 30% decrease in transfer rate. This could be useful for
134 * NetBSD or OpenBSD.
135 */
136 /* #define PIPE_NODIRECT */
137
138 #define PIPE_PEER(pipe) \
139 (((pipe)->pipe_type & PIPE_TYPE_NAMED) ? (pipe) : ((pipe)->pipe_peer))
140
141 /*
142 * interfaces to the outside world
143 */
144 static fo_rdwr_t pipe_read;
145 static fo_rdwr_t pipe_write;
146 static fo_truncate_t pipe_truncate;
147 static fo_ioctl_t pipe_ioctl;
148 static fo_poll_t pipe_poll;
149 static fo_kqfilter_t pipe_kqfilter;
150 static fo_stat_t pipe_stat;
151 static fo_close_t pipe_close;
152 static fo_chmod_t pipe_chmod;
153 static fo_chown_t pipe_chown;
154 static fo_fill_kinfo_t pipe_fill_kinfo;
155
156 const struct fileops pipeops = {
157 .fo_read = pipe_read,
158 .fo_write = pipe_write,
159 .fo_truncate = pipe_truncate,
160 .fo_ioctl = pipe_ioctl,
161 .fo_poll = pipe_poll,
162 .fo_kqfilter = pipe_kqfilter,
163 .fo_stat = pipe_stat,
164 .fo_close = pipe_close,
165 .fo_chmod = pipe_chmod,
166 .fo_chown = pipe_chown,
167 .fo_sendfile = invfo_sendfile,
168 .fo_fill_kinfo = pipe_fill_kinfo,
169 .fo_cmp = file_kcmp_generic,
170 .fo_flags = DFLAG_PASSABLE
171 };
172
173 static void filt_pipedetach(struct knote *kn);
174 static void filt_pipedetach_notsup(struct knote *kn);
175 static int filt_pipenotsup(struct knote *kn, long hint);
176 static int filt_piperead(struct knote *kn, long hint);
177 static int filt_pipewrite(struct knote *kn, long hint);
178 static int filt_pipedump(struct proc *p, struct knote *kn,
179 struct kinfo_knote *kin);
180
181 static const struct filterops pipe_nfiltops = {
182 .f_isfd = 1,
183 .f_detach = filt_pipedetach_notsup,
184 .f_event = filt_pipenotsup,
185 /* no userdump */
186 .f_copy = knote_triv_copy,
187 };
188 static const struct filterops pipe_rfiltops = {
189 .f_isfd = 1,
190 .f_detach = filt_pipedetach,
191 .f_event = filt_piperead,
192 .f_userdump = filt_pipedump,
193 .f_copy = knote_triv_copy,
194 };
195 static const struct filterops pipe_wfiltops = {
196 .f_isfd = 1,
197 .f_detach = filt_pipedetach,
198 .f_event = filt_pipewrite,
199 .f_userdump = filt_pipedump,
200 .f_copy = knote_triv_copy,
201 };
202
203 /*
204 * Default pipe buffer size(s), this can be kind-of large now because pipe
205 * space is pageable. The pipe code will try to maintain locality of
206 * reference for performance reasons, so small amounts of outstanding I/O
207 * will not wipe the cache.
208 */
209 #define MINPIPESIZE (PIPE_SIZE/3)
210 #define MAXPIPESIZE (2*PIPE_SIZE/3)
211
212 static long amountpipekva;
213 static int pipefragretry;
214 static int pipeallocfail;
215 static int piperesizefail;
216 static int piperesizeallowed = 1;
217 static long pipe_mindirect = PIPE_MINDIRECT;
218 static int pipebuf_reserv = 2;
219
220 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
221 &maxpipekva, 0, "Pipe KVA limit");
222 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD,
223 &amountpipekva, 0, "Pipe KVA usage");
224 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD,
225 &pipefragretry, 0, "Pipe allocation retries due to fragmentation");
226 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD,
227 &pipeallocfail, 0, "Pipe allocation failures");
228 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD,
229 &piperesizefail, 0, "Pipe resize failures");
230 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW,
231 &piperesizeallowed, 0, "Pipe resizing allowed");
232 SYSCTL_INT(_kern_ipc, OID_AUTO, pipebuf_reserv, CTLFLAG_RW,
233 &pipebuf_reserv, 0,
234 "Superuser-reserved percentage of the pipe buffers space");
235
236 static void pipeinit(void *dummy __unused);
237 static void pipeclose(struct pipe *cpipe);
238 static void pipe_free_kmem(struct pipe *cpipe);
239 static int pipe_create(struct pipe *pipe, bool backing);
240 static void pipe_destroy(struct pipe *pipe);
241 static int pipe_paircreate(struct thread *td, struct pipepair **p_pp);
242 static __inline int pipelock(struct pipe *cpipe, bool catch);
243 static __inline void pipeunlock(struct pipe *cpipe);
244 static void pipe_timestamp(struct timespec *tsp);
245 #ifndef PIPE_NODIRECT
246 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio);
247 static void pipe_destroy_write_buffer(struct pipe *wpipe);
248 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio);
249 static void pipe_clone_write_buffer(struct pipe *wpipe);
250 #endif
251 static int pipespace(struct pipe *cpipe, int size);
252 static int pipespace_new(struct pipe *cpipe, int size);
253
254 static int pipe_zone_ctor(void *mem, int size, void *arg, int flags);
255 static int pipe_zone_init(void *mem, int size, int flags);
256 static void pipe_zone_fini(void *mem, int size);
257
258 static uma_zone_t pipe_zone;
259 static struct unrhdr64 pipeino_unr;
260 static dev_t pipedev_ino;
261
262 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
263
264 static void
pipeinit(void * dummy __unused)265 pipeinit(void *dummy __unused)
266 {
267
268 pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair),
269 pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini,
270 UMA_ALIGN_PTR, 0);
271 KASSERT(pipe_zone != NULL, ("pipe_zone not initialized"));
272 new_unrhdr64(&pipeino_unr, 1);
273 pipedev_ino = devfs_alloc_cdp_inode();
274 KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized"));
275 }
276
277 static int
sysctl_handle_pipe_mindirect(SYSCTL_HANDLER_ARGS)278 sysctl_handle_pipe_mindirect(SYSCTL_HANDLER_ARGS)
279 {
280 int error = 0;
281 long tmp_pipe_mindirect = pipe_mindirect;
282
283 error = sysctl_handle_long(oidp, &tmp_pipe_mindirect, arg2, req);
284 if (error != 0 || req->newptr == NULL)
285 return (error);
286
287 /*
288 * Don't allow pipe_mindirect to be set so low that we violate
289 * atomicity requirements.
290 */
291 if (tmp_pipe_mindirect <= PIPE_BUF)
292 return (EINVAL);
293 pipe_mindirect = tmp_pipe_mindirect;
294 return (0);
295 }
296 SYSCTL_OID(_kern_ipc, OID_AUTO, pipe_mindirect, CTLTYPE_LONG | CTLFLAG_RW,
297 &pipe_mindirect, 0, sysctl_handle_pipe_mindirect, "L",
298 "Minimum write size triggering VM optimization");
299
300 static int
pipe_zone_ctor(void * mem,int size,void * arg,int flags)301 pipe_zone_ctor(void *mem, int size, void *arg, int flags)
302 {
303 struct pipepair *pp;
304 struct pipe *rpipe, *wpipe;
305
306 KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size"));
307
308 pp = (struct pipepair *)mem;
309
310 /*
311 * We zero both pipe endpoints to make sure all the kmem pointers
312 * are NULL, flag fields are zero'd, etc. We timestamp both
313 * endpoints with the same time.
314 */
315 rpipe = &pp->pp_rpipe;
316 bzero(rpipe, sizeof(*rpipe));
317 pipe_timestamp(&rpipe->pipe_ctime);
318 rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime;
319
320 wpipe = &pp->pp_wpipe;
321 bzero(wpipe, sizeof(*wpipe));
322 wpipe->pipe_ctime = rpipe->pipe_ctime;
323 wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime;
324
325 rpipe->pipe_peer = wpipe;
326 rpipe->pipe_pair = pp;
327 wpipe->pipe_peer = rpipe;
328 wpipe->pipe_pair = pp;
329
330 /*
331 * Mark both endpoints as present; they will later get free'd
332 * one at a time. When both are free'd, then the whole pair
333 * is released.
334 */
335 rpipe->pipe_present = PIPE_ACTIVE;
336 wpipe->pipe_present = PIPE_ACTIVE;
337
338 /*
339 * Eventually, the MAC Framework may initialize the label
340 * in ctor or init, but for now we do it elswhere to avoid
341 * blocking in ctor or init.
342 */
343 pp->pp_label = NULL;
344
345 return (0);
346 }
347
348 static int
pipe_zone_init(void * mem,int size,int flags)349 pipe_zone_init(void *mem, int size, int flags)
350 {
351 struct pipepair *pp;
352
353 KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size"));
354
355 pp = (struct pipepair *)mem;
356
357 mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_NEW);
358 return (0);
359 }
360
361 static void
pipe_zone_fini(void * mem,int size)362 pipe_zone_fini(void *mem, int size)
363 {
364 struct pipepair *pp;
365
366 KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size"));
367
368 pp = (struct pipepair *)mem;
369
370 mtx_destroy(&pp->pp_mtx);
371 }
372
373 static int
pipe_paircreate(struct thread * td,struct pipepair ** p_pp)374 pipe_paircreate(struct thread *td, struct pipepair **p_pp)
375 {
376 struct pipepair *pp;
377 struct pipe *rpipe, *wpipe;
378 int error;
379
380 *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK);
381 #ifdef MAC
382 /*
383 * The MAC label is shared between the connected endpoints. As a
384 * result mac_pipe_init() and mac_pipe_create() are called once
385 * for the pair, and not on the endpoints.
386 */
387 mac_pipe_init(pp);
388 mac_pipe_create(td->td_ucred, pp);
389 #endif
390 rpipe = &pp->pp_rpipe;
391 wpipe = &pp->pp_wpipe;
392 pp->pp_owner = crhold(td->td_ucred);
393
394 knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe));
395 knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe));
396
397 /*
398 * Only the forward direction pipe is backed by big buffer by
399 * default.
400 */
401 error = pipe_create(rpipe, true);
402 if (error != 0)
403 goto fail;
404 error = pipe_create(wpipe, false);
405 if (error != 0) {
406 pipe_destroy(rpipe);
407 goto fail;
408 }
409
410 rpipe->pipe_state |= PIPE_DIRECTOK;
411 wpipe->pipe_state |= PIPE_DIRECTOK;
412 return (0);
413
414 fail:
415 knlist_destroy(&rpipe->pipe_sel.si_note);
416 knlist_destroy(&wpipe->pipe_sel.si_note);
417 crfree(pp->pp_owner);
418 #ifdef MAC
419 mac_pipe_destroy(pp);
420 #endif
421 uma_zfree(pipe_zone, pp);
422 return (error);
423 }
424
425 int
pipe_named_ctor(struct pipe ** ppipe,struct thread * td)426 pipe_named_ctor(struct pipe **ppipe, struct thread *td)
427 {
428 struct pipepair *pp;
429 int error;
430
431 error = pipe_paircreate(td, &pp);
432 if (error != 0)
433 return (error);
434 pp->pp_rpipe.pipe_type |= PIPE_TYPE_NAMED;
435 *ppipe = &pp->pp_rpipe;
436 return (0);
437 }
438
439 void
pipe_dtor(struct pipe * dpipe)440 pipe_dtor(struct pipe *dpipe)
441 {
442 struct pipe *peer;
443
444 peer = (dpipe->pipe_type & PIPE_TYPE_NAMED) != 0 ? dpipe->pipe_peer : NULL;
445 funsetown(&dpipe->pipe_sigio);
446 pipeclose(dpipe);
447 if (peer != NULL) {
448 funsetown(&peer->pipe_sigio);
449 pipeclose(peer);
450 }
451 }
452
453 /*
454 * Get a timestamp.
455 *
456 * This used to be vfs_timestamp but the higher precision is unnecessary and
457 * can very negatively affect performance in virtualized environments (e.g., on
458 * vms running on amd64 when using the rdtscp instruction).
459 */
460 static void
pipe_timestamp(struct timespec * tsp)461 pipe_timestamp(struct timespec *tsp)
462 {
463
464 getnanotime(tsp);
465 }
466
467 /*
468 * The pipe system call for the DTYPE_PIPE type of pipes. If we fail, let
469 * the zone pick up the pieces via pipeclose().
470 */
471 int
kern_pipe(struct thread * td,int fildes[2],int flags,struct filecaps * fcaps1,struct filecaps * fcaps2)472 kern_pipe(struct thread *td, int fildes[2], int flags, struct filecaps *fcaps1,
473 struct filecaps *fcaps2)
474 {
475 struct file *rf, *wf;
476 struct pipe *rpipe, *wpipe;
477 struct pipepair *pp;
478 int fd, fflags, error;
479
480 error = pipe_paircreate(td, &pp);
481 if (error != 0)
482 return (error);
483 rpipe = &pp->pp_rpipe;
484 wpipe = &pp->pp_wpipe;
485 error = falloc_caps(td, &rf, &fd, flags, fcaps1);
486 if (error) {
487 pipeclose(rpipe);
488 pipeclose(wpipe);
489 return (error);
490 }
491 /* An extra reference on `rf' has been held for us by falloc_caps(). */
492 fildes[0] = fd;
493
494 fflags = FREAD | FWRITE;
495 if ((flags & O_NONBLOCK) != 0)
496 fflags |= FNONBLOCK;
497
498 /*
499 * Warning: once we've gotten past allocation of the fd for the
500 * read-side, we can only drop the read side via fdrop() in order
501 * to avoid races against processes which manage to dup() the read
502 * side while we are blocked trying to allocate the write side.
503 */
504 finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops);
505 error = falloc_caps(td, &wf, &fd, flags, fcaps2);
506 if (error) {
507 fdclose(td, rf, fildes[0]);
508 fdrop(rf, td);
509 /* rpipe has been closed by fdrop(). */
510 pipeclose(wpipe);
511 return (error);
512 }
513 /* An extra reference on `wf' has been held for us by falloc_caps(). */
514 finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops);
515 fdrop(wf, td);
516 fildes[1] = fd;
517 fdrop(rf, td);
518
519 return (0);
520 }
521
522 #ifdef COMPAT_FREEBSD10
523 /* ARGSUSED */
524 int
freebsd10_pipe(struct thread * td,struct freebsd10_pipe_args * uap __unused)525 freebsd10_pipe(struct thread *td, struct freebsd10_pipe_args *uap __unused)
526 {
527 int error;
528 int fildes[2];
529
530 error = kern_pipe(td, fildes, 0, NULL, NULL);
531 if (error)
532 return (error);
533
534 td->td_retval[0] = fildes[0];
535 td->td_retval[1] = fildes[1];
536
537 return (0);
538 }
539 #endif
540
541 int
sys_pipe2(struct thread * td,struct pipe2_args * uap)542 sys_pipe2(struct thread *td, struct pipe2_args *uap)
543 {
544 int error, fildes[2];
545
546 if ((uap->flags & ~(O_CLOEXEC | O_CLOFORK | O_NONBLOCK)) != 0)
547 return (EINVAL);
548 error = kern_pipe(td, fildes, uap->flags, NULL, NULL);
549 if (error)
550 return (error);
551 error = copyout(fildes, uap->fildes, 2 * sizeof(int));
552 if (error) {
553 (void)kern_close(td, fildes[0]);
554 (void)kern_close(td, fildes[1]);
555 }
556 return (error);
557 }
558
559 /*
560 * Allocate kva for pipe circular buffer, the space is pageable
561 * This routine will 'realloc' the size of a pipe safely, if it fails
562 * it will retain the old buffer.
563 * If it fails it will return ENOMEM.
564 */
565 static int
pipespace_new(struct pipe * cpipe,int size)566 pipespace_new(struct pipe *cpipe, int size)
567 {
568 caddr_t buffer;
569 int error, cnt, firstseg;
570 static int curfail = 0;
571 static struct timeval lastfail;
572
573 PIPE_LOCK_ASSERT(cpipe, MA_NOTOWNED);
574 KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW),
575 ("pipespace: resize of direct writes not allowed"));
576 retry:
577 cnt = cpipe->pipe_buffer.cnt;
578 if (cnt > size)
579 size = cnt;
580
581 size = round_page(size);
582 buffer = (caddr_t) vm_map_min(pipe_map);
583
584 if (!chgpipecnt(cpipe->pipe_pair->pp_owner->cr_ruidinfo,
585 size, lim_cur(curthread, RLIMIT_PIPEBUF))) {
586 if (cpipe->pipe_buffer.buffer == NULL &&
587 size > SMALL_PIPE_SIZE) {
588 size = SMALL_PIPE_SIZE;
589 goto retry;
590 }
591 return (ENOMEM);
592 }
593
594 vm_map_lock(pipe_map);
595 if (priv_check(curthread, PRIV_PIPEBUF) != 0 && maxpipekva / 100 *
596 (100 - pipebuf_reserv) < amountpipekva + size) {
597 vm_map_unlock(pipe_map);
598 chgpipecnt(cpipe->pipe_pair->pp_owner->cr_ruidinfo, -size, 0);
599 if (cpipe->pipe_buffer.buffer == NULL &&
600 size > SMALL_PIPE_SIZE) {
601 size = SMALL_PIPE_SIZE;
602 pipefragretry++;
603 goto retry;
604 }
605 return (ENOMEM);
606 }
607 error = vm_map_find_locked(pipe_map, NULL, 0, (vm_offset_t *)&buffer,
608 size, 0, VMFS_ANY_SPACE, VM_PROT_RW, VM_PROT_RW, 0);
609 vm_map_unlock(pipe_map);
610 if (error != KERN_SUCCESS) {
611 chgpipecnt(cpipe->pipe_pair->pp_owner->cr_ruidinfo, -size, 0);
612 if (cpipe->pipe_buffer.buffer == NULL &&
613 size > SMALL_PIPE_SIZE) {
614 size = SMALL_PIPE_SIZE;
615 pipefragretry++;
616 goto retry;
617 }
618 if (cpipe->pipe_buffer.buffer == NULL) {
619 pipeallocfail++;
620 if (ppsratecheck(&lastfail, &curfail, 1))
621 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n");
622 } else {
623 piperesizefail++;
624 }
625 return (ENOMEM);
626 }
627
628 /* copy data, then free old resources if we're resizing */
629 if (cnt > 0) {
630 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) {
631 firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out;
632 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
633 buffer, firstseg);
634 if ((cnt - firstseg) > 0)
635 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg],
636 cpipe->pipe_buffer.in);
637 } else {
638 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
639 buffer, cnt);
640 }
641 }
642 pipe_free_kmem(cpipe);
643 cpipe->pipe_buffer.buffer = buffer;
644 cpipe->pipe_buffer.size = size;
645 cpipe->pipe_buffer.in = cnt;
646 cpipe->pipe_buffer.out = 0;
647 cpipe->pipe_buffer.cnt = cnt;
648 atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size);
649 return (0);
650 }
651
652 /*
653 * Wrapper for pipespace_new() that performs locking assertions.
654 */
655 static int
pipespace(struct pipe * cpipe,int size)656 pipespace(struct pipe *cpipe, int size)
657 {
658
659 KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
660 ("Unlocked pipe passed to pipespace"));
661 return (pipespace_new(cpipe, size));
662 }
663
664 /*
665 * lock a pipe for I/O, blocking other access
666 */
667 static __inline int
pipelock(struct pipe * cpipe,bool catch)668 pipelock(struct pipe *cpipe, bool catch)
669 {
670 int error, prio;
671
672 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
673
674 prio = PRIBIO;
675 if (catch)
676 prio |= PCATCH;
677 while (cpipe->pipe_state & PIPE_LOCKFL) {
678 KASSERT(cpipe->pipe_waiters >= 0,
679 ("%s: bad waiter count %d", __func__,
680 cpipe->pipe_waiters));
681 cpipe->pipe_waiters++;
682 error = msleep(&cpipe->pipe_waiters, PIPE_MTX(cpipe), prio,
683 "pipelk", 0);
684 cpipe->pipe_waiters--;
685 if (error != 0)
686 return (error);
687 }
688 cpipe->pipe_state |= PIPE_LOCKFL;
689 return (0);
690 }
691
692 /*
693 * unlock a pipe I/O lock
694 */
695 static __inline void
pipeunlock(struct pipe * cpipe)696 pipeunlock(struct pipe *cpipe)
697 {
698
699 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
700 KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
701 ("Unlocked pipe passed to pipeunlock"));
702 KASSERT(cpipe->pipe_waiters >= 0,
703 ("%s: bad waiter count %d", __func__,
704 cpipe->pipe_waiters));
705 cpipe->pipe_state &= ~PIPE_LOCKFL;
706 if (cpipe->pipe_waiters > 0)
707 wakeup_one(&cpipe->pipe_waiters);
708 }
709
710 void
pipeselwakeup(struct pipe * cpipe)711 pipeselwakeup(struct pipe *cpipe)
712 {
713
714 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
715 if (cpipe->pipe_state & PIPE_SEL) {
716 selwakeuppri(&cpipe->pipe_sel, PSOCK);
717 if (!SEL_WAITING(&cpipe->pipe_sel))
718 cpipe->pipe_state &= ~PIPE_SEL;
719 }
720 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
721 pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
722 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0);
723 }
724
725 /*
726 * Initialize and allocate VM and memory for pipe. The structure
727 * will start out zero'd from the ctor, so we just manage the kmem.
728 */
729 static int
pipe_create(struct pipe * pipe,bool large_backing)730 pipe_create(struct pipe *pipe, bool large_backing)
731 {
732 int error;
733
734 error = pipespace_new(pipe, !large_backing || amountpipekva >
735 maxpipekva / 2 ? SMALL_PIPE_SIZE : PIPE_SIZE);
736 if (error == 0)
737 pipe->pipe_ino = alloc_unr64(&pipeino_unr);
738 return (error);
739 }
740
741 static void
pipe_destroy(struct pipe * pipe)742 pipe_destroy(struct pipe *pipe)
743 {
744 pipe_free_kmem(pipe);
745 /*
746 * Note: we "leak" pipe_ino -- by design the alloc_unr64 mechanism does
747 * not undo allocations.
748 */
749 }
750
751 /* ARGSUSED */
752 static int
pipe_read(struct file * fp,struct uio * uio,struct ucred * active_cred,int flags,struct thread * td)753 pipe_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
754 int flags, struct thread *td)
755 {
756 struct pipe *rpipe;
757 int error;
758 int nread = 0;
759 int size;
760
761 rpipe = fp->f_data;
762
763 /*
764 * Try to avoid locking the pipe if we have nothing to do.
765 *
766 * There are programs which share one pipe amongst multiple processes
767 * and perform non-blocking reads in parallel, even if the pipe is
768 * empty. This in particular is the case with BSD make, which when
769 * spawned with a high -j number can find itself with over half of the
770 * calls failing to find anything.
771 */
772 if ((fp->f_flag & FNONBLOCK) != 0 && !mac_pipe_check_read_enabled()) {
773 if (__predict_false(uio->uio_resid == 0))
774 return (0);
775 if ((atomic_load_short(&rpipe->pipe_state) & PIPE_EOF) == 0 &&
776 atomic_load_int(&rpipe->pipe_buffer.cnt) == 0 &&
777 atomic_load_int(&rpipe->pipe_pages.cnt) == 0)
778 return (EAGAIN);
779 }
780
781 PIPE_LOCK(rpipe);
782 ++rpipe->pipe_busy;
783 error = pipelock(rpipe, true);
784 if (error)
785 goto unlocked_error;
786
787 #ifdef MAC
788 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair);
789 if (error)
790 goto locked_error;
791 #endif
792 if (amountpipekva > (3 * maxpipekva) / 4) {
793 if ((rpipe->pipe_state & PIPE_DIRECTW) == 0 &&
794 rpipe->pipe_buffer.size > SMALL_PIPE_SIZE &&
795 rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE &&
796 piperesizeallowed == 1) {
797 PIPE_UNLOCK(rpipe);
798 pipespace(rpipe, SMALL_PIPE_SIZE);
799 PIPE_LOCK(rpipe);
800 }
801 }
802
803 while (uio->uio_resid) {
804 /*
805 * normal pipe buffer receive
806 */
807 if (rpipe->pipe_buffer.cnt > 0) {
808 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
809 if (size > rpipe->pipe_buffer.cnt)
810 size = rpipe->pipe_buffer.cnt;
811 if (size > uio->uio_resid)
812 size = uio->uio_resid;
813
814 PIPE_UNLOCK(rpipe);
815 error = uiomove(
816 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
817 size, uio);
818 PIPE_LOCK(rpipe);
819 if (error)
820 break;
821
822 rpipe->pipe_buffer.out += size;
823 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
824 rpipe->pipe_buffer.out = 0;
825
826 rpipe->pipe_buffer.cnt -= size;
827
828 /*
829 * If there is no more to read in the pipe, reset
830 * its pointers to the beginning. This improves
831 * cache hit stats.
832 */
833 if (rpipe->pipe_buffer.cnt == 0) {
834 rpipe->pipe_buffer.in = 0;
835 rpipe->pipe_buffer.out = 0;
836 }
837 nread += size;
838 #ifndef PIPE_NODIRECT
839 /*
840 * Direct copy, bypassing a kernel buffer.
841 */
842 } else if ((size = rpipe->pipe_pages.cnt) != 0) {
843 if (size > uio->uio_resid)
844 size = (u_int) uio->uio_resid;
845 PIPE_UNLOCK(rpipe);
846 error = uiomove_fromphys(rpipe->pipe_pages.ms,
847 rpipe->pipe_pages.pos, size, uio);
848 PIPE_LOCK(rpipe);
849 if (error)
850 break;
851 nread += size;
852 rpipe->pipe_pages.pos += size;
853 rpipe->pipe_pages.cnt -= size;
854 if (rpipe->pipe_pages.cnt == 0) {
855 rpipe->pipe_state &= ~PIPE_WANTW;
856 wakeup(rpipe);
857 }
858 #endif
859 } else {
860 /*
861 * detect EOF condition
862 * read returns 0 on EOF, no need to set error
863 */
864 if (rpipe->pipe_state & PIPE_EOF)
865 break;
866
867 /*
868 * If the "write-side" has been blocked, wake it up now.
869 */
870 if (rpipe->pipe_state & PIPE_WANTW) {
871 rpipe->pipe_state &= ~PIPE_WANTW;
872 wakeup(rpipe);
873 }
874
875 /*
876 * Break if some data was read.
877 */
878 if (nread > 0)
879 break;
880
881 /*
882 * Unlock the pipe buffer for our remaining processing.
883 * We will either break out with an error or we will
884 * sleep and relock to loop.
885 */
886 pipeunlock(rpipe);
887
888 /*
889 * Handle non-blocking mode operation or
890 * wait for more data.
891 */
892 if (fp->f_flag & FNONBLOCK) {
893 error = EAGAIN;
894 } else {
895 rpipe->pipe_state |= PIPE_WANTR;
896 if ((error = msleep(rpipe, PIPE_MTX(rpipe),
897 PRIBIO | PCATCH,
898 "piperd", 0)) == 0)
899 error = pipelock(rpipe, true);
900 }
901 if (error)
902 goto unlocked_error;
903 }
904 }
905 #ifdef MAC
906 locked_error:
907 #endif
908 pipeunlock(rpipe);
909
910 /* XXX: should probably do this before getting any locks. */
911 if (error == 0)
912 pipe_timestamp(&rpipe->pipe_atime);
913 unlocked_error:
914 --rpipe->pipe_busy;
915
916 /*
917 * PIPE_WANT processing only makes sense if pipe_busy is 0.
918 */
919 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
920 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
921 wakeup(rpipe);
922 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
923 /*
924 * Handle write blocking hysteresis.
925 */
926 if (rpipe->pipe_state & PIPE_WANTW) {
927 rpipe->pipe_state &= ~PIPE_WANTW;
928 wakeup(rpipe);
929 }
930 }
931
932 /*
933 * Only wake up writers if there was actually something read.
934 * Otherwise, when calling read(2) at EOF, a spurious wakeup occurs.
935 */
936 if (nread > 0 &&
937 rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt >= PIPE_BUF)
938 pipeselwakeup(rpipe);
939
940 PIPE_UNLOCK(rpipe);
941 if (nread > 0)
942 td->td_ru.ru_msgrcv++;
943 return (error);
944 }
945
946 #ifndef PIPE_NODIRECT
947 /*
948 * Map the sending processes' buffer into kernel space and wire it.
949 * This is similar to a physical write operation.
950 */
951 static int
pipe_build_write_buffer(struct pipe * wpipe,struct uio * uio)952 pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio)
953 {
954 u_int size;
955 int i;
956
957 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
958 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0,
959 ("%s: PIPE_DIRECTW set on %p", __func__, wpipe));
960 KASSERT(wpipe->pipe_pages.cnt == 0,
961 ("%s: pipe map for %p contains residual data", __func__, wpipe));
962
963 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size)
964 size = wpipe->pipe_buffer.size;
965 else
966 size = uio->uio_iov->iov_len;
967
968 wpipe->pipe_state |= PIPE_DIRECTW;
969 PIPE_UNLOCK(wpipe);
970 i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
971 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ,
972 wpipe->pipe_pages.ms, PIPENPAGES);
973 PIPE_LOCK(wpipe);
974 if (i < 0) {
975 wpipe->pipe_state &= ~PIPE_DIRECTW;
976 return (EFAULT);
977 }
978
979 wpipe->pipe_pages.npages = i;
980 wpipe->pipe_pages.pos =
981 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK;
982 wpipe->pipe_pages.cnt = size;
983
984 uio->uio_iov->iov_len -= size;
985 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size;
986 if (uio->uio_iov->iov_len == 0) {
987 uio->uio_iov++;
988 uio->uio_iovcnt--;
989 }
990 uio->uio_resid -= size;
991 uio->uio_offset += size;
992 return (0);
993 }
994
995 /*
996 * Unwire the process buffer.
997 */
998 static void
pipe_destroy_write_buffer(struct pipe * wpipe)999 pipe_destroy_write_buffer(struct pipe *wpipe)
1000 {
1001
1002 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
1003 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0,
1004 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe));
1005 KASSERT(wpipe->pipe_pages.cnt == 0,
1006 ("%s: pipe map for %p contains residual data", __func__, wpipe));
1007
1008 wpipe->pipe_state &= ~PIPE_DIRECTW;
1009 vm_page_unhold_pages(wpipe->pipe_pages.ms, wpipe->pipe_pages.npages);
1010 wpipe->pipe_pages.npages = 0;
1011 }
1012
1013 /*
1014 * In the case of a signal, the writing process might go away. This
1015 * code copies the data into the circular buffer so that the source
1016 * pages can be freed without loss of data.
1017 */
1018 static void
pipe_clone_write_buffer(struct pipe * wpipe)1019 pipe_clone_write_buffer(struct pipe *wpipe)
1020 {
1021 struct uio uio;
1022 struct iovec iov;
1023 int size;
1024 int pos;
1025
1026 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
1027 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0,
1028 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe));
1029
1030 size = wpipe->pipe_pages.cnt;
1031 pos = wpipe->pipe_pages.pos;
1032 wpipe->pipe_pages.cnt = 0;
1033
1034 wpipe->pipe_buffer.in = size;
1035 wpipe->pipe_buffer.out = 0;
1036 wpipe->pipe_buffer.cnt = size;
1037
1038 PIPE_UNLOCK(wpipe);
1039 iov.iov_base = wpipe->pipe_buffer.buffer;
1040 iov.iov_len = size;
1041 uio.uio_iov = &iov;
1042 uio.uio_iovcnt = 1;
1043 uio.uio_offset = 0;
1044 uio.uio_resid = size;
1045 uio.uio_segflg = UIO_SYSSPACE;
1046 uio.uio_rw = UIO_READ;
1047 uio.uio_td = curthread;
1048 uiomove_fromphys(wpipe->pipe_pages.ms, pos, size, &uio);
1049 PIPE_LOCK(wpipe);
1050 pipe_destroy_write_buffer(wpipe);
1051 }
1052
1053 /*
1054 * This implements the pipe buffer write mechanism. Note that only
1055 * a direct write OR a normal pipe write can be pending at any given time.
1056 * If there are any characters in the pipe buffer, the direct write will
1057 * be deferred until the receiving process grabs all of the bytes from
1058 * the pipe buffer. Then the direct mapping write is set-up.
1059 */
1060 static int
pipe_direct_write(struct pipe * wpipe,struct uio * uio)1061 pipe_direct_write(struct pipe *wpipe, struct uio *uio)
1062 {
1063 int error;
1064
1065 retry:
1066 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
1067 if ((wpipe->pipe_state & PIPE_EOF) != 0) {
1068 error = EPIPE;
1069 goto error1;
1070 }
1071 if (wpipe->pipe_state & PIPE_DIRECTW) {
1072 if (wpipe->pipe_state & PIPE_WANTR) {
1073 wpipe->pipe_state &= ~PIPE_WANTR;
1074 wakeup(wpipe);
1075 }
1076 pipeselwakeup(wpipe);
1077 wpipe->pipe_state |= PIPE_WANTW;
1078 pipeunlock(wpipe);
1079 error = msleep(wpipe, PIPE_MTX(wpipe),
1080 PRIBIO | PCATCH, "pipdww", 0);
1081 pipelock(wpipe, false);
1082 if (error != 0)
1083 goto error1;
1084 goto retry;
1085 }
1086 if (wpipe->pipe_buffer.cnt > 0) {
1087 if (wpipe->pipe_state & PIPE_WANTR) {
1088 wpipe->pipe_state &= ~PIPE_WANTR;
1089 wakeup(wpipe);
1090 }
1091 pipeselwakeup(wpipe);
1092 wpipe->pipe_state |= PIPE_WANTW;
1093 pipeunlock(wpipe);
1094 error = msleep(wpipe, PIPE_MTX(wpipe),
1095 PRIBIO | PCATCH, "pipdwc", 0);
1096 pipelock(wpipe, false);
1097 if (error != 0)
1098 goto error1;
1099 goto retry;
1100 }
1101
1102 error = pipe_build_write_buffer(wpipe, uio);
1103 if (error) {
1104 goto error1;
1105 }
1106
1107 while (wpipe->pipe_pages.cnt != 0 &&
1108 (wpipe->pipe_state & PIPE_EOF) == 0) {
1109 if (wpipe->pipe_state & PIPE_WANTR) {
1110 wpipe->pipe_state &= ~PIPE_WANTR;
1111 wakeup(wpipe);
1112 }
1113 pipeselwakeup(wpipe);
1114 wpipe->pipe_state |= PIPE_WANTW;
1115 pipeunlock(wpipe);
1116 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
1117 "pipdwt", 0);
1118 pipelock(wpipe, false);
1119 if (error != 0)
1120 break;
1121 }
1122
1123 if ((wpipe->pipe_state & PIPE_EOF) != 0) {
1124 wpipe->pipe_pages.cnt = 0;
1125 pipe_destroy_write_buffer(wpipe);
1126 pipeselwakeup(wpipe);
1127 error = EPIPE;
1128 } else if (error == EINTR || error == ERESTART) {
1129 pipe_clone_write_buffer(wpipe);
1130 } else {
1131 pipe_destroy_write_buffer(wpipe);
1132 }
1133 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0,
1134 ("pipe %p leaked PIPE_DIRECTW", wpipe));
1135 return (error);
1136
1137 error1:
1138 wakeup(wpipe);
1139 return (error);
1140 }
1141 #endif
1142
1143 static int
pipe_write(struct file * fp,struct uio * uio,struct ucred * active_cred,int flags,struct thread * td)1144 pipe_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
1145 int flags, struct thread *td)
1146 {
1147 struct pipe *wpipe, *rpipe;
1148 ssize_t orig_resid;
1149 int desiredsize, error;
1150
1151 rpipe = fp->f_data;
1152 wpipe = PIPE_PEER(rpipe);
1153 PIPE_LOCK(rpipe);
1154 error = pipelock(wpipe, true);
1155 if (error) {
1156 PIPE_UNLOCK(rpipe);
1157 return (error);
1158 }
1159 /*
1160 * detect loss of pipe read side, issue SIGPIPE if lost.
1161 */
1162 if (wpipe->pipe_present != PIPE_ACTIVE ||
1163 (wpipe->pipe_state & PIPE_EOF)) {
1164 pipeunlock(wpipe);
1165 PIPE_UNLOCK(rpipe);
1166 return (EPIPE);
1167 }
1168 #ifdef MAC
1169 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair);
1170 if (error) {
1171 pipeunlock(wpipe);
1172 PIPE_UNLOCK(rpipe);
1173 return (error);
1174 }
1175 #endif
1176 ++wpipe->pipe_busy;
1177
1178 /* Choose a larger size if it's advantageous */
1179 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size);
1180 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) {
1181 if (piperesizeallowed != 1)
1182 break;
1183 if (amountpipekva > maxpipekva / 2)
1184 break;
1185 if (desiredsize == BIG_PIPE_SIZE)
1186 break;
1187 desiredsize = desiredsize * 2;
1188 }
1189
1190 /* Choose a smaller size if we're in a OOM situation */
1191 if (amountpipekva > (3 * maxpipekva) / 4 &&
1192 wpipe->pipe_buffer.size > SMALL_PIPE_SIZE &&
1193 wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE &&
1194 piperesizeallowed == 1)
1195 desiredsize = SMALL_PIPE_SIZE;
1196
1197 /* Resize if the above determined that a new size was necessary */
1198 if (desiredsize != wpipe->pipe_buffer.size &&
1199 (wpipe->pipe_state & PIPE_DIRECTW) == 0) {
1200 PIPE_UNLOCK(wpipe);
1201 pipespace(wpipe, desiredsize);
1202 PIPE_LOCK(wpipe);
1203 }
1204 MPASS(wpipe->pipe_buffer.size != 0);
1205
1206 orig_resid = uio->uio_resid;
1207
1208 while (uio->uio_resid) {
1209 int space;
1210
1211 if (wpipe->pipe_state & PIPE_EOF) {
1212 error = EPIPE;
1213 break;
1214 }
1215 #ifndef PIPE_NODIRECT
1216 /*
1217 * If the transfer is large, we can gain performance if
1218 * we do process-to-process copies directly.
1219 * If the write is non-blocking, we don't use the
1220 * direct write mechanism.
1221 *
1222 * The direct write mechanism will detect the reader going
1223 * away on us.
1224 */
1225 if (uio->uio_segflg == UIO_USERSPACE &&
1226 uio->uio_iov->iov_len >= pipe_mindirect &&
1227 wpipe->pipe_buffer.size >= pipe_mindirect &&
1228 (fp->f_flag & FNONBLOCK) == 0) {
1229 error = pipe_direct_write(wpipe, uio);
1230 if (error != 0)
1231 break;
1232 continue;
1233 }
1234 #endif
1235
1236 /*
1237 * Pipe buffered writes cannot be coincidental with
1238 * direct writes. We wait until the currently executing
1239 * direct write is completed before we start filling the
1240 * pipe buffer. We break out if a signal occurs or the
1241 * reader goes away.
1242 */
1243 if (wpipe->pipe_pages.cnt != 0) {
1244 if (wpipe->pipe_state & PIPE_WANTR) {
1245 wpipe->pipe_state &= ~PIPE_WANTR;
1246 wakeup(wpipe);
1247 }
1248 pipeselwakeup(wpipe);
1249 wpipe->pipe_state |= PIPE_WANTW;
1250 pipeunlock(wpipe);
1251 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH,
1252 "pipbww", 0);
1253 pipelock(wpipe, false);
1254 if (error != 0)
1255 break;
1256 continue;
1257 }
1258
1259 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1260
1261 /* Writes of size <= PIPE_BUF must be atomic. */
1262 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
1263 space = 0;
1264
1265 if (space > 0) {
1266 int size; /* Transfer size */
1267 int segsize; /* first segment to transfer */
1268
1269 /*
1270 * Transfer size is minimum of uio transfer
1271 * and free space in pipe buffer.
1272 */
1273 if (space > uio->uio_resid)
1274 size = uio->uio_resid;
1275 else
1276 size = space;
1277 /*
1278 * First segment to transfer is minimum of
1279 * transfer size and contiguous space in
1280 * pipe buffer. If first segment to transfer
1281 * is less than the transfer size, we've got
1282 * a wraparound in the buffer.
1283 */
1284 segsize = wpipe->pipe_buffer.size -
1285 wpipe->pipe_buffer.in;
1286 if (segsize > size)
1287 segsize = size;
1288
1289 /* Transfer first segment */
1290
1291 PIPE_UNLOCK(rpipe);
1292 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
1293 segsize, uio);
1294 PIPE_LOCK(rpipe);
1295
1296 if (error == 0 && segsize < size) {
1297 KASSERT(wpipe->pipe_buffer.in + segsize ==
1298 wpipe->pipe_buffer.size,
1299 ("Pipe buffer wraparound disappeared"));
1300 /*
1301 * Transfer remaining part now, to
1302 * support atomic writes. Wraparound
1303 * happened.
1304 */
1305
1306 PIPE_UNLOCK(rpipe);
1307 error = uiomove(
1308 &wpipe->pipe_buffer.buffer[0],
1309 size - segsize, uio);
1310 PIPE_LOCK(rpipe);
1311 }
1312 if (error == 0) {
1313 wpipe->pipe_buffer.in += size;
1314 if (wpipe->pipe_buffer.in >=
1315 wpipe->pipe_buffer.size) {
1316 KASSERT(wpipe->pipe_buffer.in ==
1317 size - segsize +
1318 wpipe->pipe_buffer.size,
1319 ("Expected wraparound bad"));
1320 wpipe->pipe_buffer.in = size - segsize;
1321 }
1322
1323 wpipe->pipe_buffer.cnt += size;
1324 KASSERT(wpipe->pipe_buffer.cnt <=
1325 wpipe->pipe_buffer.size,
1326 ("Pipe buffer overflow"));
1327 }
1328 if (error != 0)
1329 break;
1330 continue;
1331 } else {
1332 /*
1333 * If the "read-side" has been blocked, wake it up now.
1334 */
1335 if (wpipe->pipe_state & PIPE_WANTR) {
1336 wpipe->pipe_state &= ~PIPE_WANTR;
1337 wakeup(wpipe);
1338 }
1339
1340 /*
1341 * don't block on non-blocking I/O
1342 */
1343 if (fp->f_flag & FNONBLOCK) {
1344 error = EAGAIN;
1345 break;
1346 }
1347
1348 /*
1349 * We have no more space and have something to offer,
1350 * wake up select/poll.
1351 */
1352 pipeselwakeup(wpipe);
1353
1354 wpipe->pipe_state |= PIPE_WANTW;
1355 pipeunlock(wpipe);
1356 error = msleep(wpipe, PIPE_MTX(rpipe),
1357 PRIBIO | PCATCH, "pipewr", 0);
1358 pipelock(wpipe, false);
1359 if (error != 0)
1360 break;
1361 continue;
1362 }
1363 }
1364
1365 --wpipe->pipe_busy;
1366
1367 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1368 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1369 wakeup(wpipe);
1370 } else if (wpipe->pipe_buffer.cnt > 0) {
1371 /*
1372 * If we have put any characters in the buffer, we wake up
1373 * the reader.
1374 */
1375 if (wpipe->pipe_state & PIPE_WANTR) {
1376 wpipe->pipe_state &= ~PIPE_WANTR;
1377 wakeup(wpipe);
1378 }
1379 }
1380
1381 /*
1382 * Don't return EPIPE if any byte was written.
1383 * EINTR and other interrupts are handled by generic I/O layer.
1384 * Do not pretend that I/O succeeded for obvious user error
1385 * like EFAULT.
1386 */
1387 if (uio->uio_resid != orig_resid && error == EPIPE)
1388 error = 0;
1389
1390 if (error == 0)
1391 pipe_timestamp(&wpipe->pipe_mtime);
1392
1393 /*
1394 * We have something to offer,
1395 * wake up select/poll.
1396 */
1397 if (wpipe->pipe_buffer.cnt)
1398 pipeselwakeup(wpipe);
1399
1400 pipeunlock(wpipe);
1401 PIPE_UNLOCK(rpipe);
1402 if (uio->uio_resid != orig_resid)
1403 td->td_ru.ru_msgsnd++;
1404 return (error);
1405 }
1406
1407 /* ARGSUSED */
1408 static int
pipe_truncate(struct file * fp,off_t length,struct ucred * active_cred,struct thread * td)1409 pipe_truncate(struct file *fp, off_t length, struct ucred *active_cred,
1410 struct thread *td)
1411 {
1412 struct pipe *cpipe;
1413 int error;
1414
1415 cpipe = fp->f_data;
1416 if (cpipe->pipe_type & PIPE_TYPE_NAMED)
1417 error = vnops.fo_truncate(fp, length, active_cred, td);
1418 else
1419 error = invfo_truncate(fp, length, active_cred, td);
1420 return (error);
1421 }
1422
1423 /*
1424 * we implement a very minimal set of ioctls for compatibility with sockets.
1425 */
1426 static int
pipe_ioctl(struct file * fp,u_long cmd,void * data,struct ucred * active_cred,struct thread * td)1427 pipe_ioctl(struct file *fp, u_long cmd, void *data, struct ucred *active_cred,
1428 struct thread *td)
1429 {
1430 struct pipe *mpipe = fp->f_data;
1431 int error;
1432
1433 PIPE_LOCK(mpipe);
1434
1435 #ifdef MAC
1436 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data);
1437 if (error) {
1438 PIPE_UNLOCK(mpipe);
1439 return (error);
1440 }
1441 #endif
1442
1443 error = 0;
1444 switch (cmd) {
1445 case FIONBIO:
1446 break;
1447
1448 case FIOASYNC:
1449 if (*(int *)data) {
1450 mpipe->pipe_state |= PIPE_ASYNC;
1451 } else {
1452 mpipe->pipe_state &= ~PIPE_ASYNC;
1453 }
1454 break;
1455
1456 case FIONREAD:
1457 if (!(fp->f_flag & FREAD)) {
1458 *(int *)data = 0;
1459 PIPE_UNLOCK(mpipe);
1460 return (0);
1461 }
1462 if (mpipe->pipe_pages.cnt != 0)
1463 *(int *)data = mpipe->pipe_pages.cnt;
1464 else
1465 *(int *)data = mpipe->pipe_buffer.cnt;
1466 break;
1467
1468 case FIOSETOWN:
1469 PIPE_UNLOCK(mpipe);
1470 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
1471 goto out_unlocked;
1472
1473 case FIOGETOWN:
1474 *(int *)data = fgetown(&mpipe->pipe_sigio);
1475 break;
1476
1477 /* This is deprecated, FIOSETOWN should be used instead. */
1478 case TIOCSPGRP:
1479 PIPE_UNLOCK(mpipe);
1480 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
1481 goto out_unlocked;
1482
1483 /* This is deprecated, FIOGETOWN should be used instead. */
1484 case TIOCGPGRP:
1485 *(int *)data = -fgetown(&mpipe->pipe_sigio);
1486 break;
1487
1488 default:
1489 error = ENOTTY;
1490 break;
1491 }
1492 PIPE_UNLOCK(mpipe);
1493 out_unlocked:
1494 return (error);
1495 }
1496
1497 static int
pipe_poll(struct file * fp,int events,struct ucred * active_cred,struct thread * td)1498 pipe_poll(struct file *fp, int events, struct ucred *active_cred,
1499 struct thread *td)
1500 {
1501 struct pipe *rpipe;
1502 struct pipe *wpipe;
1503 int levents, revents;
1504 #ifdef MAC
1505 int error;
1506 #endif
1507
1508 revents = 0;
1509 rpipe = fp->f_data;
1510 wpipe = PIPE_PEER(rpipe);
1511 PIPE_LOCK(rpipe);
1512 #ifdef MAC
1513 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair);
1514 if (error)
1515 goto locked_error;
1516 #endif
1517 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM))
1518 if (rpipe->pipe_pages.cnt > 0 || rpipe->pipe_buffer.cnt > 0)
1519 revents |= events & (POLLIN | POLLRDNORM);
1520
1521 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM))
1522 if (wpipe->pipe_present != PIPE_ACTIVE ||
1523 (wpipe->pipe_state & PIPE_EOF) ||
1524 ((wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
1525 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF ||
1526 wpipe->pipe_buffer.size == 0)))
1527 revents |= events & (POLLOUT | POLLWRNORM);
1528
1529 levents = events &
1530 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND);
1531 if (rpipe->pipe_type & PIPE_TYPE_NAMED && fp->f_flag & FREAD && levents &&
1532 fp->f_pipegen == rpipe->pipe_wgen)
1533 events |= POLLINIGNEOF;
1534
1535 if ((events & POLLINIGNEOF) == 0) {
1536 if (rpipe->pipe_state & PIPE_EOF) {
1537 if (fp->f_flag & FREAD)
1538 revents |= (events & (POLLIN | POLLRDNORM));
1539 if (wpipe->pipe_present != PIPE_ACTIVE ||
1540 (wpipe->pipe_state & PIPE_EOF))
1541 revents |= POLLHUP;
1542 }
1543 }
1544
1545 if (revents == 0) {
1546 /*
1547 * Add ourselves regardless of eventmask as we have to return
1548 * POLLHUP even if it was not asked for.
1549 */
1550 if ((fp->f_flag & FREAD) != 0) {
1551 selrecord(td, &rpipe->pipe_sel);
1552 if (SEL_WAITING(&rpipe->pipe_sel))
1553 rpipe->pipe_state |= PIPE_SEL;
1554 }
1555
1556 if ((fp->f_flag & FWRITE) != 0 &&
1557 wpipe->pipe_present == PIPE_ACTIVE) {
1558 selrecord(td, &wpipe->pipe_sel);
1559 if (SEL_WAITING(&wpipe->pipe_sel))
1560 wpipe->pipe_state |= PIPE_SEL;
1561 }
1562 }
1563 #ifdef MAC
1564 locked_error:
1565 #endif
1566 PIPE_UNLOCK(rpipe);
1567
1568 return (revents);
1569 }
1570
1571 /*
1572 * We shouldn't need locks here as we're doing a read and this should
1573 * be a natural race.
1574 */
1575 static int
pipe_stat(struct file * fp,struct stat * ub,struct ucred * active_cred)1576 pipe_stat(struct file *fp, struct stat *ub, struct ucred *active_cred)
1577 {
1578 struct pipe *pipe;
1579 #ifdef MAC
1580 int error;
1581 #endif
1582
1583 pipe = fp->f_data;
1584 #ifdef MAC
1585 if (mac_pipe_check_stat_enabled()) {
1586 PIPE_LOCK(pipe);
1587 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair);
1588 PIPE_UNLOCK(pipe);
1589 if (error) {
1590 return (error);
1591 }
1592 }
1593 #endif
1594
1595 /* For named pipes ask the underlying filesystem. */
1596 if (pipe->pipe_type & PIPE_TYPE_NAMED) {
1597 return (vnops.fo_stat(fp, ub, active_cred));
1598 }
1599
1600 bzero(ub, sizeof(*ub));
1601 ub->st_mode = S_IFIFO;
1602 ub->st_blksize = PAGE_SIZE;
1603 if (pipe->pipe_pages.cnt != 0)
1604 ub->st_size = pipe->pipe_pages.cnt;
1605 else
1606 ub->st_size = pipe->pipe_buffer.cnt;
1607 ub->st_blocks = howmany(ub->st_size, ub->st_blksize);
1608 ub->st_atim = pipe->pipe_atime;
1609 ub->st_mtim = pipe->pipe_mtime;
1610 ub->st_ctim = pipe->pipe_ctime;
1611 ub->st_uid = fp->f_cred->cr_uid;
1612 ub->st_gid = fp->f_cred->cr_gid;
1613 ub->st_dev = pipedev_ino;
1614 ub->st_ino = pipe->pipe_ino;
1615 /*
1616 * Left as 0: st_nlink, st_rdev, st_flags, st_gen.
1617 */
1618 return (0);
1619 }
1620
1621 /* ARGSUSED */
1622 static int
pipe_close(struct file * fp,struct thread * td)1623 pipe_close(struct file *fp, struct thread *td)
1624 {
1625
1626 if (fp->f_vnode != NULL)
1627 return vnops.fo_close(fp, td);
1628 fp->f_ops = &badfileops;
1629 pipe_dtor(fp->f_data);
1630 fp->f_data = NULL;
1631 return (0);
1632 }
1633
1634 static int
pipe_chmod(struct file * fp,mode_t mode,struct ucred * active_cred,struct thread * td)1635 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td)
1636 {
1637 struct pipe *cpipe;
1638 int error;
1639
1640 cpipe = fp->f_data;
1641 if (cpipe->pipe_type & PIPE_TYPE_NAMED)
1642 error = vn_chmod(fp, mode, active_cred, td);
1643 else
1644 error = invfo_chmod(fp, mode, active_cred, td);
1645 return (error);
1646 }
1647
1648 static int
pipe_chown(struct file * fp,uid_t uid,gid_t gid,struct ucred * active_cred,struct thread * td)1649 pipe_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
1650 struct thread *td)
1651 {
1652 struct pipe *cpipe;
1653 int error;
1654
1655 cpipe = fp->f_data;
1656 if (cpipe->pipe_type & PIPE_TYPE_NAMED)
1657 error = vn_chown(fp, uid, gid, active_cred, td);
1658 else
1659 error = invfo_chown(fp, uid, gid, active_cred, td);
1660 return (error);
1661 }
1662
1663 static int
pipe_fill_kinfo(struct file * fp,struct kinfo_file * kif,struct filedesc * fdp)1664 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
1665 {
1666 struct pipe *pi;
1667
1668 if (fp->f_type == DTYPE_FIFO)
1669 return (vn_fill_kinfo(fp, kif, fdp));
1670 kif->kf_type = KF_TYPE_PIPE;
1671 pi = fp->f_data;
1672 kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi;
1673 kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer;
1674 kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt;
1675 kif->kf_un.kf_pipe.kf_pipe_buffer_in = pi->pipe_buffer.in;
1676 kif->kf_un.kf_pipe.kf_pipe_buffer_out = pi->pipe_buffer.out;
1677 kif->kf_un.kf_pipe.kf_pipe_buffer_size = pi->pipe_buffer.size;
1678 return (0);
1679 }
1680
1681 static void
pipe_free_kmem(struct pipe * cpipe)1682 pipe_free_kmem(struct pipe *cpipe)
1683 {
1684
1685 PIPE_LOCK_ASSERT(cpipe, MA_NOTOWNED);
1686
1687 if (cpipe->pipe_buffer.buffer != NULL) {
1688 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size);
1689 chgpipecnt(cpipe->pipe_pair->pp_owner->cr_ruidinfo,
1690 -cpipe->pipe_buffer.size, 0);
1691 vm_map_remove(pipe_map,
1692 (vm_offset_t)cpipe->pipe_buffer.buffer,
1693 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size);
1694 cpipe->pipe_buffer.buffer = NULL;
1695 }
1696 #ifndef PIPE_NODIRECT
1697 {
1698 cpipe->pipe_pages.cnt = 0;
1699 cpipe->pipe_pages.pos = 0;
1700 cpipe->pipe_pages.npages = 0;
1701 }
1702 #endif
1703 }
1704
1705 /*
1706 * shutdown the pipe
1707 */
1708 static void
pipeclose(struct pipe * cpipe)1709 pipeclose(struct pipe *cpipe)
1710 {
1711 #ifdef MAC
1712 struct pipepair *pp;
1713 #endif
1714 struct pipe *ppipe;
1715
1716 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL"));
1717
1718 PIPE_LOCK(cpipe);
1719 pipelock(cpipe, false);
1720 #ifdef MAC
1721 pp = cpipe->pipe_pair;
1722 #endif
1723
1724 /*
1725 * If the other side is blocked, wake it up saying that
1726 * we want to close it down.
1727 */
1728 cpipe->pipe_state |= PIPE_EOF;
1729 while (cpipe->pipe_busy) {
1730 wakeup(cpipe);
1731 cpipe->pipe_state |= PIPE_WANT;
1732 pipeunlock(cpipe);
1733 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
1734 pipelock(cpipe, false);
1735 }
1736
1737 pipeselwakeup(cpipe);
1738
1739 /*
1740 * Disconnect from peer, if any.
1741 */
1742 ppipe = cpipe->pipe_peer;
1743 if (ppipe->pipe_present == PIPE_ACTIVE) {
1744 ppipe->pipe_state |= PIPE_EOF;
1745 wakeup(ppipe);
1746 pipeselwakeup(ppipe);
1747 }
1748
1749 /*
1750 * Mark this endpoint as free. Release kmem resources. We
1751 * don't mark this endpoint as unused until we've finished
1752 * doing that, or the pipe might disappear out from under
1753 * us.
1754 */
1755 PIPE_UNLOCK(cpipe);
1756 pipe_free_kmem(cpipe);
1757 PIPE_LOCK(cpipe);
1758 cpipe->pipe_present = PIPE_CLOSING;
1759 pipeunlock(cpipe);
1760
1761 /*
1762 * knlist_clear() may sleep dropping the PIPE_MTX. Set the
1763 * PIPE_FINALIZED, that allows other end to free the
1764 * pipe_pair, only after the knotes are completely dismantled.
1765 */
1766 knlist_clear(&cpipe->pipe_sel.si_note, 1);
1767 cpipe->pipe_present = PIPE_FINALIZED;
1768 seldrain(&cpipe->pipe_sel);
1769 knlist_destroy(&cpipe->pipe_sel.si_note);
1770
1771 /*
1772 * If both endpoints are now closed, release the memory for the
1773 * pipe pair. If not, unlock.
1774 */
1775 if (ppipe->pipe_present == PIPE_FINALIZED) {
1776 PIPE_UNLOCK(cpipe);
1777 crfree(cpipe->pipe_pair->pp_owner);
1778 #ifdef MAC
1779 mac_pipe_destroy(pp);
1780 #endif
1781 uma_zfree(pipe_zone, cpipe->pipe_pair);
1782 } else
1783 PIPE_UNLOCK(cpipe);
1784 }
1785
1786 /*ARGSUSED*/
1787 static int
pipe_kqfilter(struct file * fp,struct knote * kn)1788 pipe_kqfilter(struct file *fp, struct knote *kn)
1789 {
1790 struct pipe *cpipe;
1791
1792 /*
1793 * If a filter is requested that is not supported by this file
1794 * descriptor, don't return an error, but also don't ever generate an
1795 * event.
1796 */
1797 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) {
1798 kn->kn_fop = &pipe_nfiltops;
1799 return (0);
1800 }
1801 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) {
1802 kn->kn_fop = &pipe_nfiltops;
1803 return (0);
1804 }
1805 cpipe = fp->f_data;
1806 PIPE_LOCK(cpipe);
1807 switch (kn->kn_filter) {
1808 case EVFILT_READ:
1809 kn->kn_fop = &pipe_rfiltops;
1810 break;
1811 case EVFILT_WRITE:
1812 kn->kn_fop = &pipe_wfiltops;
1813 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) {
1814 /* other end of pipe has been closed */
1815 PIPE_UNLOCK(cpipe);
1816 return (EPIPE);
1817 }
1818 cpipe = PIPE_PEER(cpipe);
1819 break;
1820 default:
1821 if ((cpipe->pipe_type & PIPE_TYPE_NAMED) != 0) {
1822 PIPE_UNLOCK(cpipe);
1823 return (vnops.fo_kqfilter(fp, kn));
1824 }
1825 PIPE_UNLOCK(cpipe);
1826 return (EINVAL);
1827 }
1828
1829 kn->kn_hook = cpipe;
1830 knlist_add(&cpipe->pipe_sel.si_note, kn, 1);
1831 PIPE_UNLOCK(cpipe);
1832 return (0);
1833 }
1834
1835 static void
filt_pipedetach(struct knote * kn)1836 filt_pipedetach(struct knote *kn)
1837 {
1838 struct pipe *cpipe = kn->kn_hook;
1839
1840 PIPE_LOCK(cpipe);
1841 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1);
1842 PIPE_UNLOCK(cpipe);
1843 }
1844
1845 /*ARGSUSED*/
1846 static int
filt_piperead(struct knote * kn,long hint)1847 filt_piperead(struct knote *kn, long hint)
1848 {
1849 struct file *fp = kn->kn_fp;
1850 struct pipe *rpipe = kn->kn_hook;
1851
1852 PIPE_LOCK_ASSERT(rpipe, MA_OWNED);
1853 kn->kn_data = rpipe->pipe_buffer.cnt;
1854 if (kn->kn_data == 0)
1855 kn->kn_data = rpipe->pipe_pages.cnt;
1856
1857 if ((rpipe->pipe_state & PIPE_EOF) != 0 &&
1858 ((rpipe->pipe_type & PIPE_TYPE_NAMED) == 0 ||
1859 fp->f_pipegen != rpipe->pipe_wgen)) {
1860 kn->kn_flags |= EV_EOF;
1861 return (1);
1862 }
1863 kn->kn_flags &= ~EV_EOF;
1864 return (kn->kn_data > 0);
1865 }
1866
1867 /*ARGSUSED*/
1868 static int
filt_pipewrite(struct knote * kn,long hint)1869 filt_pipewrite(struct knote *kn, long hint)
1870 {
1871 struct pipe *wpipe = kn->kn_hook;
1872
1873 /*
1874 * If this end of the pipe is closed, the knote was removed from the
1875 * knlist and the list lock (i.e., the pipe lock) is therefore not held.
1876 */
1877 if (wpipe->pipe_present == PIPE_ACTIVE ||
1878 (wpipe->pipe_type & PIPE_TYPE_NAMED) != 0) {
1879 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
1880
1881 if (wpipe->pipe_state & PIPE_DIRECTW) {
1882 kn->kn_data = 0;
1883 } else if (wpipe->pipe_buffer.size > 0) {
1884 kn->kn_data = wpipe->pipe_buffer.size -
1885 wpipe->pipe_buffer.cnt;
1886 } else {
1887 kn->kn_data = PIPE_BUF;
1888 }
1889 }
1890
1891 if (wpipe->pipe_present != PIPE_ACTIVE ||
1892 (wpipe->pipe_state & PIPE_EOF)) {
1893 kn->kn_flags |= EV_EOF;
1894 return (1);
1895 }
1896 kn->kn_flags &= ~EV_EOF;
1897 return (kn->kn_data >= PIPE_BUF);
1898 }
1899
1900 static void
filt_pipedetach_notsup(struct knote * kn)1901 filt_pipedetach_notsup(struct knote *kn)
1902 {
1903
1904 }
1905
1906 static int
filt_pipenotsup(struct knote * kn,long hint)1907 filt_pipenotsup(struct knote *kn, long hint)
1908 {
1909
1910 return (0);
1911 }
1912
1913 static int
filt_pipedump(struct proc * p,struct knote * kn,struct kinfo_knote * kin)1914 filt_pipedump(struct proc *p, struct knote *kn,
1915 struct kinfo_knote *kin)
1916 {
1917 struct pipe *pipe = kn->kn_hook;
1918
1919 kin->knt_extdata = KNOTE_EXTDATA_PIPE;
1920 kin->knt_pipe.knt_pipe_ino = pipe->pipe_ino;
1921 return (0);
1922 }
1923