FreeBSD/Linux Kernel Cross Reference
sys/kern/sys_pipe.c
1 /*
2 * Copyright (c) 1996 John S. Dyson
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice immediately at the beginning of the file, without modification,
10 * this list of conditions, and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Absolutely no warranty of function or purpose is made by the author
15 * John S. Dyson.
16 * 4. Modifications may be freely made to this file if the above conditions
17 * are met.
18 */
19
20 /*
21 * This file contains a high-performance replacement for the socket-based
22 * pipes scheme originally used in FreeBSD/4.4Lite. It does not support
23 * all features of sockets, but does do everything that pipes normally
24 * do.
25 */
26
27 /*
28 * This code has two modes of operation, a small write mode and a large
29 * write mode. The small write mode acts like conventional pipes with
30 * a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the
31 * "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT
32 * and PIPE_SIZE in size, it is fully mapped and wired into the kernel, and
33 * the receiving process can copy it directly from the pages in the sending
34 * process.
35 *
36 * If the sending process receives a signal, it is possible that it will
37 * go away, and certainly its address space can change, because control
38 * is returned back to the user-mode side. In that case, the pipe code
39 * arranges to copy the buffer supplied by the user process, to a pageable
40 * kernel buffer, and the receiving process will grab the data from the
41 * pageable kernel buffer. Since signals don't happen all that often,
42 * the copy operation is normally eliminated.
43 *
44 * The constant PIPE_MINDIRECT is chosen to make sure that buffering will
45 * happen for small transfers so that the system will not spend all of
46 * its time context switching.
47 *
48 * In order to limit the resource use of pipes, two sysctls exist:
49 *
50 * kern.ipc.maxpipekva - This is a hard limit on the amount of pageable
51 * address space available to us in pipe_map. This value is normally
52 * autotuned, but may also be loader tuned.
53 *
54 * kern.ipc.pipekva - This read-only sysctl tracks the current amount of
55 * memory in use by pipes.
56 *
57 * Based on how large pipekva is relative to maxpipekva, the following
58 * will happen:
59 *
60 * 0% - 50%:
61 * New pipes are given 16K of memory backing, pipes may dynamically
62 * grow to as large as 64K where needed.
63 * 50% - 75%:
64 * New pipes are given 4K (or PAGE_SIZE) of memory backing,
65 * existing pipes may NOT grow.
66 * 75% - 100%:
67 * New pipes are given 4K (or PAGE_SIZE) of memory backing,
68 * existing pipes will be shrunk down to 4K whenever possible.
69 *
70 * Resizing may be disabled by setting kern.ipc.piperesizeallowed=0. If
71 * that is set, the only resize that will occur is the 0 -> SMALL_PIPE_SIZE
72 * resize which MUST occur for reverse-direction pipes when they are
73 * first used.
74 *
75 * Additional information about the current state of pipes may be obtained
76 * from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail,
77 * and kern.ipc.piperesizefail.
78 *
79 * Locking rules: There are two locks present here: A mutex, used via
80 * PIPE_LOCK, and a flag, used via pipelock(). All locking is done via
81 * the flag, as mutexes can not persist over uiomove. The mutex
82 * exists only to guard access to the flag, and is not in itself a
83 * locking mechanism. Also note that there is only a single mutex for
84 * both directions of a pipe.
85 *
86 * As pipelock() may have to sleep before it can acquire the flag, it
87 * is important to reread all data after a call to pipelock(); everything
88 * in the structure may have changed.
89 */
90
91 #include <sys/cdefs.h>
92 __FBSDID("$FreeBSD: releng/5.3/sys/kern/sys_pipe.c 136588 2004-10-16 08:43:07Z cvs2svn $");
93
94 #include "opt_mac.h"
95
96 #include <sys/param.h>
97 #include <sys/systm.h>
98 #include <sys/fcntl.h>
99 #include <sys/file.h>
100 #include <sys/filedesc.h>
101 #include <sys/filio.h>
102 #include <sys/kernel.h>
103 #include <sys/lock.h>
104 #include <sys/mac.h>
105 #include <sys/mutex.h>
106 #include <sys/ttycom.h>
107 #include <sys/stat.h>
108 #include <sys/malloc.h>
109 #include <sys/poll.h>
110 #include <sys/selinfo.h>
111 #include <sys/signalvar.h>
112 #include <sys/sysctl.h>
113 #include <sys/sysproto.h>
114 #include <sys/pipe.h>
115 #include <sys/proc.h>
116 #include <sys/vnode.h>
117 #include <sys/uio.h>
118 #include <sys/event.h>
119
120 #include <vm/vm.h>
121 #include <vm/vm_param.h>
122 #include <vm/vm_object.h>
123 #include <vm/vm_kern.h>
124 #include <vm/vm_extern.h>
125 #include <vm/pmap.h>
126 #include <vm/vm_map.h>
127 #include <vm/vm_page.h>
128 #include <vm/uma.h>
129
130 /*
131 * Use this define if you want to disable *fancy* VM things. Expect an
132 * approx 30% decrease in transfer rate. This could be useful for
133 * NetBSD or OpenBSD.
134 */
135 /* #define PIPE_NODIRECT */
136
137 /*
138 * interfaces to the outside world
139 */
140 static fo_rdwr_t pipe_read;
141 static fo_rdwr_t pipe_write;
142 static fo_ioctl_t pipe_ioctl;
143 static fo_poll_t pipe_poll;
144 static fo_kqfilter_t pipe_kqfilter;
145 static fo_stat_t pipe_stat;
146 static fo_close_t pipe_close;
147
148 static struct fileops pipeops = {
149 .fo_read = pipe_read,
150 .fo_write = pipe_write,
151 .fo_ioctl = pipe_ioctl,
152 .fo_poll = pipe_poll,
153 .fo_kqfilter = pipe_kqfilter,
154 .fo_stat = pipe_stat,
155 .fo_close = pipe_close,
156 .fo_flags = DFLAG_PASSABLE
157 };
158
159 static void filt_pipedetach(struct knote *kn);
160 static int filt_piperead(struct knote *kn, long hint);
161 static int filt_pipewrite(struct knote *kn, long hint);
162
163 static struct filterops pipe_rfiltops =
164 { 1, NULL, filt_pipedetach, filt_piperead };
165 static struct filterops pipe_wfiltops =
166 { 1, NULL, filt_pipedetach, filt_pipewrite };
167
168 /*
169 * Default pipe buffer size(s), this can be kind-of large now because pipe
170 * space is pageable. The pipe code will try to maintain locality of
171 * reference for performance reasons, so small amounts of outstanding I/O
172 * will not wipe the cache.
173 */
174 #define MINPIPESIZE (PIPE_SIZE/3)
175 #define MAXPIPESIZE (2*PIPE_SIZE/3)
176
177 static int amountpipes;
178 static int amountpipekva;
179 static int pipefragretry;
180 static int pipeallocfail;
181 static int piperesizefail;
182 static int piperesizeallowed = 1;
183
184 SYSCTL_DECL(_kern_ipc);
185
186 SYSCTL_INT(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN,
187 &maxpipekva, 0, "Pipe KVA limit");
188 SYSCTL_INT(_kern_ipc, OID_AUTO, pipes, CTLFLAG_RD,
189 &amountpipes, 0, "Current # of pipes");
190 SYSCTL_INT(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD,
191 &amountpipekva, 0, "Pipe KVA usage");
192 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD,
193 &pipefragretry, 0, "Pipe allocation retries due to fragmentation");
194 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD,
195 &pipeallocfail, 0, "Pipe allocation failures");
196 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD,
197 &piperesizefail, 0, "Pipe resize failures");
198 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW,
199 &piperesizeallowed, 0, "Pipe resizing allowed");
200
201 static void pipeinit(void *dummy __unused);
202 static void pipeclose(struct pipe *cpipe);
203 static void pipe_free_kmem(struct pipe *cpipe);
204 static int pipe_create(struct pipe *pipe, int backing);
205 static __inline int pipelock(struct pipe *cpipe, int catch);
206 static __inline void pipeunlock(struct pipe *cpipe);
207 static __inline void pipeselwakeup(struct pipe *cpipe);
208 #ifndef PIPE_NODIRECT
209 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio);
210 static void pipe_destroy_write_buffer(struct pipe *wpipe);
211 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio);
212 static void pipe_clone_write_buffer(struct pipe *wpipe);
213 #endif
214 static int pipespace(struct pipe *cpipe, int size);
215 static int pipespace_new(struct pipe *cpipe, int size);
216
217 static int pipe_zone_ctor(void *mem, int size, void *arg, int flags);
218 static void pipe_zone_dtor(void *mem, int size, void *arg);
219 static int pipe_zone_init(void *mem, int size, int flags);
220 static void pipe_zone_fini(void *mem, int size);
221
222 static uma_zone_t pipe_zone;
223
224 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
225
226 static void
227 pipeinit(void *dummy __unused)
228 {
229
230 pipe_zone = uma_zcreate("PIPE", sizeof(struct pipepair),
231 pipe_zone_ctor, pipe_zone_dtor, pipe_zone_init, pipe_zone_fini,
232 UMA_ALIGN_PTR, 0);
233 KASSERT(pipe_zone != NULL, ("pipe_zone not initialized"));
234 }
235
236 static int
237 pipe_zone_ctor(void *mem, int size, void *arg, int flags)
238 {
239 struct pipepair *pp;
240 struct pipe *rpipe, *wpipe;
241
242 KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size"));
243
244 pp = (struct pipepair *)mem;
245
246 /*
247 * We zero both pipe endpoints to make sure all the kmem pointers
248 * are NULL, flag fields are zero'd, etc. We timestamp both
249 * endpoints with the same time.
250 */
251 rpipe = &pp->pp_rpipe;
252 bzero(rpipe, sizeof(*rpipe));
253 vfs_timestamp(&rpipe->pipe_ctime);
254 rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime;
255
256 wpipe = &pp->pp_wpipe;
257 bzero(wpipe, sizeof(*wpipe));
258 wpipe->pipe_ctime = rpipe->pipe_ctime;
259 wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime;
260
261 rpipe->pipe_peer = wpipe;
262 rpipe->pipe_pair = pp;
263 wpipe->pipe_peer = rpipe;
264 wpipe->pipe_pair = pp;
265
266 /*
267 * Mark both endpoints as present; they will later get free'd
268 * one at a time. When both are free'd, then the whole pair
269 * is released.
270 */
271 rpipe->pipe_present = 1;
272 wpipe->pipe_present = 1;
273
274 /*
275 * Eventually, the MAC Framework may initialize the label
276 * in ctor or init, but for now we do it elswhere to avoid
277 * blocking in ctor or init.
278 */
279 pp->pp_label = NULL;
280
281 atomic_add_int(&amountpipes, 2);
282 return (0);
283 }
284
285 static void
286 pipe_zone_dtor(void *mem, int size, void *arg)
287 {
288 struct pipepair *pp;
289
290 KASSERT(size == sizeof(*pp), ("pipe_zone_dtor: wrong size"));
291
292 pp = (struct pipepair *)mem;
293
294 atomic_subtract_int(&amountpipes, 2);
295 }
296
297 static int
298 pipe_zone_init(void *mem, int size, int flags)
299 {
300 struct pipepair *pp;
301
302 KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size"));
303
304 pp = (struct pipepair *)mem;
305
306 mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_RECURSE);
307 return (0);
308 }
309
310 static void
311 pipe_zone_fini(void *mem, int size)
312 {
313 struct pipepair *pp;
314
315 KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size"));
316
317 pp = (struct pipepair *)mem;
318
319 mtx_destroy(&pp->pp_mtx);
320 }
321
322 /*
323 * The pipe system call for the DTYPE_PIPE type of pipes. If we fail,
324 * let the zone pick up the pieces via pipeclose().
325 */
326
327 /* ARGSUSED */
328 int
329 pipe(td, uap)
330 struct thread *td;
331 struct pipe_args /* {
332 int dummy;
333 } */ *uap;
334 {
335 struct filedesc *fdp = td->td_proc->p_fd;
336 struct file *rf, *wf;
337 struct pipepair *pp;
338 struct pipe *rpipe, *wpipe;
339 int fd, error;
340
341 pp = uma_zalloc(pipe_zone, M_WAITOK);
342 #ifdef MAC
343 /*
344 * The MAC label is shared between the connected endpoints. As a
345 * result mac_init_pipe() and mac_create_pipe() are called once
346 * for the pair, and not on the endpoints.
347 */
348 mac_init_pipe(pp);
349 mac_create_pipe(td->td_ucred, pp);
350 #endif
351 rpipe = &pp->pp_rpipe;
352 wpipe = &pp->pp_wpipe;
353
354 /* Only the forward direction pipe is backed by default */
355 if (pipe_create(rpipe, 1) || pipe_create(wpipe, 0)) {
356 pipeclose(rpipe);
357 pipeclose(wpipe);
358 return (ENFILE);
359 }
360
361 rpipe->pipe_state |= PIPE_DIRECTOK;
362 wpipe->pipe_state |= PIPE_DIRECTOK;
363
364 error = falloc(td, &rf, &fd);
365 if (error) {
366 pipeclose(rpipe);
367 pipeclose(wpipe);
368 return (error);
369 }
370 /* An extra reference on `rf' has been held for us by falloc(). */
371 td->td_retval[0] = fd;
372
373 /*
374 * Warning: once we've gotten past allocation of the fd for the
375 * read-side, we can only drop the read side via fdrop() in order
376 * to avoid races against processes which manage to dup() the read
377 * side while we are blocked trying to allocate the write side.
378 */
379 FILE_LOCK(rf);
380 rf->f_flag = FREAD | FWRITE;
381 rf->f_type = DTYPE_PIPE;
382 rf->f_data = rpipe;
383 rf->f_ops = &pipeops;
384 FILE_UNLOCK(rf);
385 error = falloc(td, &wf, &fd);
386 if (error) {
387 FILEDESC_LOCK(fdp);
388 if (fdp->fd_ofiles[td->td_retval[0]] == rf) {
389 fdp->fd_ofiles[td->td_retval[0]] = NULL;
390 fdunused(fdp, td->td_retval[0]);
391 FILEDESC_UNLOCK(fdp);
392 fdrop(rf, td);
393 } else {
394 FILEDESC_UNLOCK(fdp);
395 }
396 fdrop(rf, td);
397 /* rpipe has been closed by fdrop(). */
398 pipeclose(wpipe);
399 return (error);
400 }
401 /* An extra reference on `wf' has been held for us by falloc(). */
402 FILE_LOCK(wf);
403 wf->f_flag = FREAD | FWRITE;
404 wf->f_type = DTYPE_PIPE;
405 wf->f_data = wpipe;
406 wf->f_ops = &pipeops;
407 FILE_UNLOCK(wf);
408 fdrop(wf, td);
409 td->td_retval[1] = fd;
410 fdrop(rf, td);
411
412 return (0);
413 }
414
415 /*
416 * Allocate kva for pipe circular buffer, the space is pageable
417 * This routine will 'realloc' the size of a pipe safely, if it fails
418 * it will retain the old buffer.
419 * If it fails it will return ENOMEM.
420 */
421 static int
422 pipespace_new(cpipe, size)
423 struct pipe *cpipe;
424 int size;
425 {
426 caddr_t buffer;
427 int error, cnt, firstseg;
428 static int curfail = 0;
429 static struct timeval lastfail;
430
431 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked"));
432 KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW),
433 ("pipespace: resize of direct writes not allowed"));
434 retry:
435 cnt = cpipe->pipe_buffer.cnt;
436 if (cnt > size)
437 size = cnt;
438
439 size = round_page(size);
440 buffer = (caddr_t) vm_map_min(pipe_map);
441
442 error = vm_map_find(pipe_map, NULL, 0,
443 (vm_offset_t *) &buffer, size, 1,
444 VM_PROT_ALL, VM_PROT_ALL, 0);
445 if (error != KERN_SUCCESS) {
446 if ((cpipe->pipe_buffer.buffer == NULL) &&
447 (size > SMALL_PIPE_SIZE)) {
448 size = SMALL_PIPE_SIZE;
449 pipefragretry++;
450 goto retry;
451 }
452 if (cpipe->pipe_buffer.buffer == NULL) {
453 pipeallocfail++;
454 if (ppsratecheck(&lastfail, &curfail, 1))
455 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n");
456 } else {
457 piperesizefail++;
458 }
459 return (ENOMEM);
460 }
461
462 /* copy data, then free old resources if we're resizing */
463 if (cnt > 0) {
464 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) {
465 firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out;
466 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
467 buffer, firstseg);
468 if ((cnt - firstseg) > 0)
469 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg],
470 cpipe->pipe_buffer.in);
471 } else {
472 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
473 buffer, cnt);
474 }
475 }
476 pipe_free_kmem(cpipe);
477 cpipe->pipe_buffer.buffer = buffer;
478 cpipe->pipe_buffer.size = size;
479 cpipe->pipe_buffer.in = cnt;
480 cpipe->pipe_buffer.out = 0;
481 cpipe->pipe_buffer.cnt = cnt;
482 atomic_add_int(&amountpipekva, cpipe->pipe_buffer.size);
483 return (0);
484 }
485
486 /*
487 * Wrapper for pipespace_new() that performs locking assertions.
488 */
489 static int
490 pipespace(cpipe, size)
491 struct pipe *cpipe;
492 int size;
493 {
494
495 KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
496 ("Unlocked pipe passed to pipespace"));
497 return (pipespace_new(cpipe, size));
498 }
499
500 /*
501 * lock a pipe for I/O, blocking other access
502 */
503 static __inline int
504 pipelock(cpipe, catch)
505 struct pipe *cpipe;
506 int catch;
507 {
508 int error;
509
510 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
511 while (cpipe->pipe_state & PIPE_LOCKFL) {
512 cpipe->pipe_state |= PIPE_LWANT;
513 error = msleep(cpipe, PIPE_MTX(cpipe),
514 catch ? (PRIBIO | PCATCH) : PRIBIO,
515 "pipelk", 0);
516 if (error != 0)
517 return (error);
518 }
519 cpipe->pipe_state |= PIPE_LOCKFL;
520 return (0);
521 }
522
523 /*
524 * unlock a pipe I/O lock
525 */
526 static __inline void
527 pipeunlock(cpipe)
528 struct pipe *cpipe;
529 {
530
531 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
532 KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
533 ("Unlocked pipe passed to pipeunlock"));
534 cpipe->pipe_state &= ~PIPE_LOCKFL;
535 if (cpipe->pipe_state & PIPE_LWANT) {
536 cpipe->pipe_state &= ~PIPE_LWANT;
537 wakeup(cpipe);
538 }
539 }
540
541 static __inline void
542 pipeselwakeup(cpipe)
543 struct pipe *cpipe;
544 {
545
546 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
547 if (cpipe->pipe_state & PIPE_SEL) {
548 cpipe->pipe_state &= ~PIPE_SEL;
549 selwakeuppri(&cpipe->pipe_sel, PSOCK);
550 }
551 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
552 pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
553 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0);
554 }
555
556 /*
557 * Initialize and allocate VM and memory for pipe. The structure
558 * will start out zero'd from the ctor, so we just manage the kmem.
559 */
560 static int
561 pipe_create(pipe, backing)
562 struct pipe *pipe;
563 int backing;
564 {
565 int error;
566
567 if (backing) {
568 if (amountpipekva > maxpipekva / 2)
569 error = pipespace_new(pipe, SMALL_PIPE_SIZE);
570 else
571 error = pipespace_new(pipe, PIPE_SIZE);
572 } else {
573 /* If we're not backing this pipe, no need to do anything. */
574 error = 0;
575 }
576 knlist_init(&pipe->pipe_sel.si_note, PIPE_MTX(pipe));
577 return (error);
578 }
579
580 /* ARGSUSED */
581 static int
582 pipe_read(fp, uio, active_cred, flags, td)
583 struct file *fp;
584 struct uio *uio;
585 struct ucred *active_cred;
586 struct thread *td;
587 int flags;
588 {
589 struct pipe *rpipe = fp->f_data;
590 int error;
591 int nread = 0;
592 u_int size;
593
594 PIPE_LOCK(rpipe);
595 ++rpipe->pipe_busy;
596 error = pipelock(rpipe, 1);
597 if (error)
598 goto unlocked_error;
599
600 #ifdef MAC
601 error = mac_check_pipe_read(active_cred, rpipe->pipe_pair);
602 if (error)
603 goto locked_error;
604 #endif
605 if (amountpipekva > (3 * maxpipekva) / 4) {
606 if (!(rpipe->pipe_state & PIPE_DIRECTW) &&
607 (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
608 (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
609 (piperesizeallowed == 1)) {
610 PIPE_UNLOCK(rpipe);
611 pipespace(rpipe, SMALL_PIPE_SIZE);
612 PIPE_LOCK(rpipe);
613 }
614 }
615
616 while (uio->uio_resid) {
617 /*
618 * normal pipe buffer receive
619 */
620 if (rpipe->pipe_buffer.cnt > 0) {
621 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
622 if (size > rpipe->pipe_buffer.cnt)
623 size = rpipe->pipe_buffer.cnt;
624 if (size > (u_int) uio->uio_resid)
625 size = (u_int) uio->uio_resid;
626
627 PIPE_UNLOCK(rpipe);
628 error = uiomove(
629 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
630 size, uio);
631 PIPE_LOCK(rpipe);
632 if (error)
633 break;
634
635 rpipe->pipe_buffer.out += size;
636 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
637 rpipe->pipe_buffer.out = 0;
638
639 rpipe->pipe_buffer.cnt -= size;
640
641 /*
642 * If there is no more to read in the pipe, reset
643 * its pointers to the beginning. This improves
644 * cache hit stats.
645 */
646 if (rpipe->pipe_buffer.cnt == 0) {
647 rpipe->pipe_buffer.in = 0;
648 rpipe->pipe_buffer.out = 0;
649 }
650 nread += size;
651 #ifndef PIPE_NODIRECT
652 /*
653 * Direct copy, bypassing a kernel buffer.
654 */
655 } else if ((size = rpipe->pipe_map.cnt) &&
656 (rpipe->pipe_state & PIPE_DIRECTW)) {
657 if (size > (u_int) uio->uio_resid)
658 size = (u_int) uio->uio_resid;
659
660 PIPE_UNLOCK(rpipe);
661 error = uiomove_fromphys(rpipe->pipe_map.ms,
662 rpipe->pipe_map.pos, size, uio);
663 PIPE_LOCK(rpipe);
664 if (error)
665 break;
666 nread += size;
667 rpipe->pipe_map.pos += size;
668 rpipe->pipe_map.cnt -= size;
669 if (rpipe->pipe_map.cnt == 0) {
670 rpipe->pipe_state &= ~PIPE_DIRECTW;
671 wakeup(rpipe);
672 }
673 #endif
674 } else {
675 /*
676 * detect EOF condition
677 * read returns 0 on EOF, no need to set error
678 */
679 if (rpipe->pipe_state & PIPE_EOF)
680 break;
681
682 /*
683 * If the "write-side" has been blocked, wake it up now.
684 */
685 if (rpipe->pipe_state & PIPE_WANTW) {
686 rpipe->pipe_state &= ~PIPE_WANTW;
687 wakeup(rpipe);
688 }
689
690 /*
691 * Break if some data was read.
692 */
693 if (nread > 0)
694 break;
695
696 /*
697 * Unlock the pipe buffer for our remaining processing.
698 * We will either break out with an error or we will
699 * sleep and relock to loop.
700 */
701 pipeunlock(rpipe);
702
703 /*
704 * Handle non-blocking mode operation or
705 * wait for more data.
706 */
707 if (fp->f_flag & FNONBLOCK) {
708 error = EAGAIN;
709 } else {
710 rpipe->pipe_state |= PIPE_WANTR;
711 if ((error = msleep(rpipe, PIPE_MTX(rpipe),
712 PRIBIO | PCATCH,
713 "piperd", 0)) == 0)
714 error = pipelock(rpipe, 1);
715 }
716 if (error)
717 goto unlocked_error;
718 }
719 }
720 #ifdef MAC
721 locked_error:
722 #endif
723 pipeunlock(rpipe);
724
725 /* XXX: should probably do this before getting any locks. */
726 if (error == 0)
727 vfs_timestamp(&rpipe->pipe_atime);
728 unlocked_error:
729 --rpipe->pipe_busy;
730
731 /*
732 * PIPE_WANT processing only makes sense if pipe_busy is 0.
733 */
734 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
735 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
736 wakeup(rpipe);
737 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
738 /*
739 * Handle write blocking hysteresis.
740 */
741 if (rpipe->pipe_state & PIPE_WANTW) {
742 rpipe->pipe_state &= ~PIPE_WANTW;
743 wakeup(rpipe);
744 }
745 }
746
747 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
748 pipeselwakeup(rpipe);
749
750 PIPE_UNLOCK(rpipe);
751 return (error);
752 }
753
754 #ifndef PIPE_NODIRECT
755 /*
756 * Map the sending processes' buffer into kernel space and wire it.
757 * This is similar to a physical write operation.
758 */
759 static int
760 pipe_build_write_buffer(wpipe, uio)
761 struct pipe *wpipe;
762 struct uio *uio;
763 {
764 pmap_t pmap;
765 u_int size;
766 int i, j;
767 vm_offset_t addr, endaddr;
768
769 PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED);
770 KASSERT(wpipe->pipe_state & PIPE_DIRECTW,
771 ("Clone attempt on non-direct write pipe!"));
772
773 size = (u_int) uio->uio_iov->iov_len;
774 if (size > wpipe->pipe_buffer.size)
775 size = wpipe->pipe_buffer.size;
776
777 pmap = vmspace_pmap(curproc->p_vmspace);
778 endaddr = round_page((vm_offset_t)uio->uio_iov->iov_base + size);
779 addr = trunc_page((vm_offset_t)uio->uio_iov->iov_base);
780 for (i = 0; addr < endaddr; addr += PAGE_SIZE, i++) {
781 /*
782 * vm_fault_quick() can sleep. Consequently,
783 * vm_page_lock_queue() and vm_page_unlock_queue()
784 * should not be performed outside of this loop.
785 */
786 race:
787 if (vm_fault_quick((caddr_t)addr, VM_PROT_READ) < 0) {
788 vm_page_lock_queues();
789 for (j = 0; j < i; j++)
790 vm_page_unhold(wpipe->pipe_map.ms[j]);
791 vm_page_unlock_queues();
792 return (EFAULT);
793 }
794 wpipe->pipe_map.ms[i] = pmap_extract_and_hold(pmap, addr,
795 VM_PROT_READ);
796 if (wpipe->pipe_map.ms[i] == NULL)
797 goto race;
798 }
799
800 /*
801 * set up the control block
802 */
803 wpipe->pipe_map.npages = i;
804 wpipe->pipe_map.pos =
805 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK;
806 wpipe->pipe_map.cnt = size;
807
808 /*
809 * and update the uio data
810 */
811
812 uio->uio_iov->iov_len -= size;
813 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size;
814 if (uio->uio_iov->iov_len == 0)
815 uio->uio_iov++;
816 uio->uio_resid -= size;
817 uio->uio_offset += size;
818 return (0);
819 }
820
821 /*
822 * unmap and unwire the process buffer
823 */
824 static void
825 pipe_destroy_write_buffer(wpipe)
826 struct pipe *wpipe;
827 {
828 int i;
829
830 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
831 vm_page_lock_queues();
832 for (i = 0; i < wpipe->pipe_map.npages; i++) {
833 vm_page_unhold(wpipe->pipe_map.ms[i]);
834 }
835 vm_page_unlock_queues();
836 wpipe->pipe_map.npages = 0;
837 }
838
839 /*
840 * In the case of a signal, the writing process might go away. This
841 * code copies the data into the circular buffer so that the source
842 * pages can be freed without loss of data.
843 */
844 static void
845 pipe_clone_write_buffer(wpipe)
846 struct pipe *wpipe;
847 {
848 struct uio uio;
849 struct iovec iov;
850 int size;
851 int pos;
852
853 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
854 size = wpipe->pipe_map.cnt;
855 pos = wpipe->pipe_map.pos;
856
857 wpipe->pipe_buffer.in = size;
858 wpipe->pipe_buffer.out = 0;
859 wpipe->pipe_buffer.cnt = size;
860 wpipe->pipe_state &= ~PIPE_DIRECTW;
861
862 PIPE_UNLOCK(wpipe);
863 iov.iov_base = wpipe->pipe_buffer.buffer;
864 iov.iov_len = size;
865 uio.uio_iov = &iov;
866 uio.uio_iovcnt = 1;
867 uio.uio_offset = 0;
868 uio.uio_resid = size;
869 uio.uio_segflg = UIO_SYSSPACE;
870 uio.uio_rw = UIO_READ;
871 uio.uio_td = curthread;
872 uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio);
873 PIPE_LOCK(wpipe);
874 pipe_destroy_write_buffer(wpipe);
875 }
876
877 /*
878 * This implements the pipe buffer write mechanism. Note that only
879 * a direct write OR a normal pipe write can be pending at any given time.
880 * If there are any characters in the pipe buffer, the direct write will
881 * be deferred until the receiving process grabs all of the bytes from
882 * the pipe buffer. Then the direct mapping write is set-up.
883 */
884 static int
885 pipe_direct_write(wpipe, uio)
886 struct pipe *wpipe;
887 struct uio *uio;
888 {
889 int error;
890
891 retry:
892 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
893 error = pipelock(wpipe, 1);
894 if (wpipe->pipe_state & PIPE_EOF)
895 error = EPIPE;
896 if (error) {
897 pipeunlock(wpipe);
898 goto error1;
899 }
900 while (wpipe->pipe_state & PIPE_DIRECTW) {
901 if (wpipe->pipe_state & PIPE_WANTR) {
902 wpipe->pipe_state &= ~PIPE_WANTR;
903 wakeup(wpipe);
904 }
905 wpipe->pipe_state |= PIPE_WANTW;
906 pipeunlock(wpipe);
907 error = msleep(wpipe, PIPE_MTX(wpipe),
908 PRIBIO | PCATCH, "pipdww", 0);
909 if (error)
910 goto error1;
911 else
912 goto retry;
913 }
914 wpipe->pipe_map.cnt = 0; /* transfer not ready yet */
915 if (wpipe->pipe_buffer.cnt > 0) {
916 if (wpipe->pipe_state & PIPE_WANTR) {
917 wpipe->pipe_state &= ~PIPE_WANTR;
918 wakeup(wpipe);
919 }
920 wpipe->pipe_state |= PIPE_WANTW;
921 pipeunlock(wpipe);
922 error = msleep(wpipe, PIPE_MTX(wpipe),
923 PRIBIO | PCATCH, "pipdwc", 0);
924 if (error)
925 goto error1;
926 else
927 goto retry;
928 }
929
930 wpipe->pipe_state |= PIPE_DIRECTW;
931
932 PIPE_UNLOCK(wpipe);
933 error = pipe_build_write_buffer(wpipe, uio);
934 PIPE_LOCK(wpipe);
935 if (error) {
936 wpipe->pipe_state &= ~PIPE_DIRECTW;
937 pipeunlock(wpipe);
938 goto error1;
939 }
940
941 error = 0;
942 while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
943 if (wpipe->pipe_state & PIPE_EOF) {
944 pipe_destroy_write_buffer(wpipe);
945 pipeselwakeup(wpipe);
946 pipeunlock(wpipe);
947 error = EPIPE;
948 goto error1;
949 }
950 if (wpipe->pipe_state & PIPE_WANTR) {
951 wpipe->pipe_state &= ~PIPE_WANTR;
952 wakeup(wpipe);
953 }
954 pipeselwakeup(wpipe);
955 pipeunlock(wpipe);
956 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
957 "pipdwt", 0);
958 pipelock(wpipe, 0);
959 }
960
961 if (wpipe->pipe_state & PIPE_EOF)
962 error = EPIPE;
963 if (wpipe->pipe_state & PIPE_DIRECTW) {
964 /*
965 * this bit of trickery substitutes a kernel buffer for
966 * the process that might be going away.
967 */
968 pipe_clone_write_buffer(wpipe);
969 } else {
970 pipe_destroy_write_buffer(wpipe);
971 }
972 pipeunlock(wpipe);
973 return (error);
974
975 error1:
976 wakeup(wpipe);
977 return (error);
978 }
979 #endif
980
981 static int
982 pipe_write(fp, uio, active_cred, flags, td)
983 struct file *fp;
984 struct uio *uio;
985 struct ucred *active_cred;
986 struct thread *td;
987 int flags;
988 {
989 int error = 0;
990 int desiredsize, orig_resid;
991 struct pipe *wpipe, *rpipe;
992
993 rpipe = fp->f_data;
994 wpipe = rpipe->pipe_peer;
995
996 PIPE_LOCK(rpipe);
997 error = pipelock(wpipe, 1);
998 if (error) {
999 PIPE_UNLOCK(rpipe);
1000 return (error);
1001 }
1002 /*
1003 * detect loss of pipe read side, issue SIGPIPE if lost.
1004 */
1005 if ((!wpipe->pipe_present) || (wpipe->pipe_state & PIPE_EOF)) {
1006 pipeunlock(wpipe);
1007 PIPE_UNLOCK(rpipe);
1008 return (EPIPE);
1009 }
1010 #ifdef MAC
1011 error = mac_check_pipe_write(active_cred, wpipe->pipe_pair);
1012 if (error) {
1013 pipeunlock(wpipe);
1014 PIPE_UNLOCK(rpipe);
1015 return (error);
1016 }
1017 #endif
1018 ++wpipe->pipe_busy;
1019
1020 /* Choose a larger size if it's advantageous */
1021 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size);
1022 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) {
1023 if (piperesizeallowed != 1)
1024 break;
1025 if (amountpipekva > maxpipekva / 2)
1026 break;
1027 if (desiredsize == BIG_PIPE_SIZE)
1028 break;
1029 desiredsize = desiredsize * 2;
1030 }
1031
1032 /* Choose a smaller size if we're in a OOM situation */
1033 if ((amountpipekva > (3 * maxpipekva) / 4) &&
1034 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
1035 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
1036 (piperesizeallowed == 1))
1037 desiredsize = SMALL_PIPE_SIZE;
1038
1039 /* Resize if the above determined that a new size was necessary */
1040 if ((desiredsize != wpipe->pipe_buffer.size) &&
1041 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) {
1042 PIPE_UNLOCK(wpipe);
1043 pipespace(wpipe, desiredsize);
1044 PIPE_LOCK(wpipe);
1045 }
1046 if (wpipe->pipe_buffer.size == 0) {
1047 /*
1048 * This can only happen for reverse direction use of pipes
1049 * in a complete OOM situation.
1050 */
1051 error = ENOMEM;
1052 --wpipe->pipe_busy;
1053 pipeunlock(wpipe);
1054 PIPE_UNLOCK(wpipe);
1055 return (error);
1056 }
1057
1058 pipeunlock(wpipe);
1059
1060 orig_resid = uio->uio_resid;
1061
1062 while (uio->uio_resid) {
1063 int space;
1064
1065 pipelock(wpipe, 0);
1066 if (wpipe->pipe_state & PIPE_EOF) {
1067 pipeunlock(wpipe);
1068 error = EPIPE;
1069 break;
1070 }
1071 #ifndef PIPE_NODIRECT
1072 /*
1073 * If the transfer is large, we can gain performance if
1074 * we do process-to-process copies directly.
1075 * If the write is non-blocking, we don't use the
1076 * direct write mechanism.
1077 *
1078 * The direct write mechanism will detect the reader going
1079 * away on us.
1080 */
1081 if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT) &&
1082 (wpipe->pipe_buffer.size >= PIPE_MINDIRECT) &&
1083 (fp->f_flag & FNONBLOCK) == 0) {
1084 pipeunlock(wpipe);
1085 error = pipe_direct_write(wpipe, uio);
1086 if (error)
1087 break;
1088 continue;
1089 }
1090 #endif
1091
1092 /*
1093 * Pipe buffered writes cannot be coincidental with
1094 * direct writes. We wait until the currently executing
1095 * direct write is completed before we start filling the
1096 * pipe buffer. We break out if a signal occurs or the
1097 * reader goes away.
1098 */
1099 if (wpipe->pipe_state & PIPE_DIRECTW) {
1100 if (wpipe->pipe_state & PIPE_WANTR) {
1101 wpipe->pipe_state &= ~PIPE_WANTR;
1102 wakeup(wpipe);
1103 }
1104 pipeunlock(wpipe);
1105 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH,
1106 "pipbww", 0);
1107 if (error)
1108 break;
1109 else
1110 continue;
1111 }
1112
1113 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1114
1115 /* Writes of size <= PIPE_BUF must be atomic. */
1116 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
1117 space = 0;
1118
1119 if (space > 0) {
1120 int size; /* Transfer size */
1121 int segsize; /* first segment to transfer */
1122
1123 /*
1124 * Transfer size is minimum of uio transfer
1125 * and free space in pipe buffer.
1126 */
1127 if (space > uio->uio_resid)
1128 size = uio->uio_resid;
1129 else
1130 size = space;
1131 /*
1132 * First segment to transfer is minimum of
1133 * transfer size and contiguous space in
1134 * pipe buffer. If first segment to transfer
1135 * is less than the transfer size, we've got
1136 * a wraparound in the buffer.
1137 */
1138 segsize = wpipe->pipe_buffer.size -
1139 wpipe->pipe_buffer.in;
1140 if (segsize > size)
1141 segsize = size;
1142
1143 /* Transfer first segment */
1144
1145 PIPE_UNLOCK(rpipe);
1146 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
1147 segsize, uio);
1148 PIPE_LOCK(rpipe);
1149
1150 if (error == 0 && segsize < size) {
1151 KASSERT(wpipe->pipe_buffer.in + segsize ==
1152 wpipe->pipe_buffer.size,
1153 ("Pipe buffer wraparound disappeared"));
1154 /*
1155 * Transfer remaining part now, to
1156 * support atomic writes. Wraparound
1157 * happened.
1158 */
1159
1160 PIPE_UNLOCK(rpipe);
1161 error = uiomove(
1162 &wpipe->pipe_buffer.buffer[0],
1163 size - segsize, uio);
1164 PIPE_LOCK(rpipe);
1165 }
1166 if (error == 0) {
1167 wpipe->pipe_buffer.in += size;
1168 if (wpipe->pipe_buffer.in >=
1169 wpipe->pipe_buffer.size) {
1170 KASSERT(wpipe->pipe_buffer.in ==
1171 size - segsize +
1172 wpipe->pipe_buffer.size,
1173 ("Expected wraparound bad"));
1174 wpipe->pipe_buffer.in = size - segsize;
1175 }
1176
1177 wpipe->pipe_buffer.cnt += size;
1178 KASSERT(wpipe->pipe_buffer.cnt <=
1179 wpipe->pipe_buffer.size,
1180 ("Pipe buffer overflow"));
1181 }
1182 pipeunlock(wpipe);
1183 } else {
1184 /*
1185 * If the "read-side" has been blocked, wake it up now.
1186 */
1187 if (wpipe->pipe_state & PIPE_WANTR) {
1188 wpipe->pipe_state &= ~PIPE_WANTR;
1189 wakeup(wpipe);
1190 }
1191
1192 /*
1193 * don't block on non-blocking I/O
1194 */
1195 if (fp->f_flag & FNONBLOCK) {
1196 error = EAGAIN;
1197 pipeunlock(wpipe);
1198 break;
1199 }
1200
1201 /*
1202 * We have no more space and have something to offer,
1203 * wake up select/poll.
1204 */
1205 pipeselwakeup(wpipe);
1206
1207 wpipe->pipe_state |= PIPE_WANTW;
1208 pipeunlock(wpipe);
1209 error = msleep(wpipe, PIPE_MTX(rpipe),
1210 PRIBIO | PCATCH, "pipewr", 0);
1211 if (error != 0)
1212 break;
1213 }
1214 }
1215
1216 pipelock(wpipe, 0);
1217 --wpipe->pipe_busy;
1218
1219 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1220 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1221 wakeup(wpipe);
1222 } else if (wpipe->pipe_buffer.cnt > 0) {
1223 /*
1224 * If we have put any characters in the buffer, we wake up
1225 * the reader.
1226 */
1227 if (wpipe->pipe_state & PIPE_WANTR) {
1228 wpipe->pipe_state &= ~PIPE_WANTR;
1229 wakeup(wpipe);
1230 }
1231 }
1232
1233 /*
1234 * Don't return EPIPE if I/O was successful
1235 */
1236 if ((wpipe->pipe_buffer.cnt == 0) &&
1237 (uio->uio_resid == 0) &&
1238 (error == EPIPE)) {
1239 error = 0;
1240 }
1241
1242 if (error == 0)
1243 vfs_timestamp(&wpipe->pipe_mtime);
1244
1245 /*
1246 * We have something to offer,
1247 * wake up select/poll.
1248 */
1249 if (wpipe->pipe_buffer.cnt)
1250 pipeselwakeup(wpipe);
1251
1252 pipeunlock(wpipe);
1253 PIPE_UNLOCK(rpipe);
1254 return (error);
1255 }
1256
1257 /*
1258 * we implement a very minimal set of ioctls for compatibility with sockets.
1259 */
1260 static int
1261 pipe_ioctl(fp, cmd, data, active_cred, td)
1262 struct file *fp;
1263 u_long cmd;
1264 void *data;
1265 struct ucred *active_cred;
1266 struct thread *td;
1267 {
1268 struct pipe *mpipe = fp->f_data;
1269 #ifdef MAC
1270 int error;
1271 #endif
1272
1273 PIPE_LOCK(mpipe);
1274
1275 #ifdef MAC
1276 error = mac_check_pipe_ioctl(active_cred, mpipe->pipe_pair, cmd, data);
1277 if (error) {
1278 PIPE_UNLOCK(mpipe);
1279 return (error);
1280 }
1281 #endif
1282
1283 switch (cmd) {
1284
1285 case FIONBIO:
1286 PIPE_UNLOCK(mpipe);
1287 return (0);
1288
1289 case FIOASYNC:
1290 if (*(int *)data) {
1291 mpipe->pipe_state |= PIPE_ASYNC;
1292 } else {
1293 mpipe->pipe_state &= ~PIPE_ASYNC;
1294 }
1295 PIPE_UNLOCK(mpipe);
1296 return (0);
1297
1298 case FIONREAD:
1299 if (mpipe->pipe_state & PIPE_DIRECTW)
1300 *(int *)data = mpipe->pipe_map.cnt;
1301 else
1302 *(int *)data = mpipe->pipe_buffer.cnt;
1303 PIPE_UNLOCK(mpipe);
1304 return (0);
1305
1306 case FIOSETOWN:
1307 PIPE_UNLOCK(mpipe);
1308 return (fsetown(*(int *)data, &mpipe->pipe_sigio));
1309
1310 case FIOGETOWN:
1311 PIPE_UNLOCK(mpipe);
1312 *(int *)data = fgetown(&mpipe->pipe_sigio);
1313 return (0);
1314
1315 /* This is deprecated, FIOSETOWN should be used instead. */
1316 case TIOCSPGRP:
1317 PIPE_UNLOCK(mpipe);
1318 return (fsetown(-(*(int *)data), &mpipe->pipe_sigio));
1319
1320 /* This is deprecated, FIOGETOWN should be used instead. */
1321 case TIOCGPGRP:
1322 PIPE_UNLOCK(mpipe);
1323 *(int *)data = -fgetown(&mpipe->pipe_sigio);
1324 return (0);
1325
1326 }
1327 PIPE_UNLOCK(mpipe);
1328 return (ENOTTY);
1329 }
1330
1331 static int
1332 pipe_poll(fp, events, active_cred, td)
1333 struct file *fp;
1334 int events;
1335 struct ucred *active_cred;
1336 struct thread *td;
1337 {
1338 struct pipe *rpipe = fp->f_data;
1339 struct pipe *wpipe;
1340 int revents = 0;
1341 #ifdef MAC
1342 int error;
1343 #endif
1344
1345 wpipe = rpipe->pipe_peer;
1346 PIPE_LOCK(rpipe);
1347 #ifdef MAC
1348 error = mac_check_pipe_poll(active_cred, rpipe->pipe_pair);
1349 if (error)
1350 goto locked_error;
1351 #endif
1352 if (events & (POLLIN | POLLRDNORM))
1353 if ((rpipe->pipe_state & PIPE_DIRECTW) ||
1354 (rpipe->pipe_buffer.cnt > 0) ||
1355 (rpipe->pipe_state & PIPE_EOF))
1356 revents |= events & (POLLIN | POLLRDNORM);
1357
1358 if (events & (POLLOUT | POLLWRNORM))
1359 if (!wpipe->pipe_present || (wpipe->pipe_state & PIPE_EOF) ||
1360 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
1361 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
1362 revents |= events & (POLLOUT | POLLWRNORM);
1363
1364 if ((rpipe->pipe_state & PIPE_EOF) ||
1365 (!wpipe->pipe_present) ||
1366 (wpipe->pipe_state & PIPE_EOF))
1367 revents |= POLLHUP;
1368
1369 if (revents == 0) {
1370 if (events & (POLLIN | POLLRDNORM)) {
1371 selrecord(td, &rpipe->pipe_sel);
1372 rpipe->pipe_state |= PIPE_SEL;
1373 }
1374
1375 if (events & (POLLOUT | POLLWRNORM)) {
1376 selrecord(td, &wpipe->pipe_sel);
1377 wpipe->pipe_state |= PIPE_SEL;
1378 }
1379 }
1380 #ifdef MAC
1381 locked_error:
1382 #endif
1383 PIPE_UNLOCK(rpipe);
1384
1385 return (revents);
1386 }
1387
1388 /*
1389 * We shouldn't need locks here as we're doing a read and this should
1390 * be a natural race.
1391 */
1392 static int
1393 pipe_stat(fp, ub, active_cred, td)
1394 struct file *fp;
1395 struct stat *ub;
1396 struct ucred *active_cred;
1397 struct thread *td;
1398 {
1399 struct pipe *pipe = fp->f_data;
1400 #ifdef MAC
1401 int error;
1402
1403 PIPE_LOCK(pipe);
1404 error = mac_check_pipe_stat(active_cred, pipe->pipe_pair);
1405 PIPE_UNLOCK(pipe);
1406 if (error)
1407 return (error);
1408 #endif
1409 bzero(ub, sizeof(*ub));
1410 ub->st_mode = S_IFIFO;
1411 ub->st_blksize = PAGE_SIZE;
1412 if (pipe->pipe_state & PIPE_DIRECTW)
1413 ub->st_size = pipe->pipe_map.cnt;
1414 else
1415 ub->st_size = pipe->pipe_buffer.cnt;
1416 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
1417 ub->st_atimespec = pipe->pipe_atime;
1418 ub->st_mtimespec = pipe->pipe_mtime;
1419 ub->st_ctimespec = pipe->pipe_ctime;
1420 ub->st_uid = fp->f_cred->cr_uid;
1421 ub->st_gid = fp->f_cred->cr_gid;
1422 /*
1423 * Left as 0: st_dev, st_ino, st_nlink, st_rdev, st_flags, st_gen.
1424 * XXX (st_dev, st_ino) should be unique.
1425 */
1426 return (0);
1427 }
1428
1429 /* ARGSUSED */
1430 static int
1431 pipe_close(fp, td)
1432 struct file *fp;
1433 struct thread *td;
1434 {
1435 struct pipe *cpipe = fp->f_data;
1436
1437 fp->f_ops = &badfileops;
1438 fp->f_data = NULL;
1439 funsetown(&cpipe->pipe_sigio);
1440 pipeclose(cpipe);
1441 return (0);
1442 }
1443
1444 static void
1445 pipe_free_kmem(cpipe)
1446 struct pipe *cpipe;
1447 {
1448
1449 KASSERT(!mtx_owned(PIPE_MTX(cpipe)),
1450 ("pipe_free_kmem: pipe mutex locked"));
1451
1452 if (cpipe->pipe_buffer.buffer != NULL) {
1453 atomic_subtract_int(&amountpipekva, cpipe->pipe_buffer.size);
1454 vm_map_remove(pipe_map,
1455 (vm_offset_t)cpipe->pipe_buffer.buffer,
1456 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size);
1457 cpipe->pipe_buffer.buffer = NULL;
1458 }
1459 #ifndef PIPE_NODIRECT
1460 {
1461 cpipe->pipe_map.cnt = 0;
1462 cpipe->pipe_map.pos = 0;
1463 cpipe->pipe_map.npages = 0;
1464 }
1465 #endif
1466 }
1467
1468 /*
1469 * shutdown the pipe
1470 */
1471 static void
1472 pipeclose(cpipe)
1473 struct pipe *cpipe;
1474 {
1475 struct pipepair *pp;
1476 struct pipe *ppipe;
1477
1478 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL"));
1479
1480 PIPE_LOCK(cpipe);
1481 pipelock(cpipe, 0);
1482 pp = cpipe->pipe_pair;
1483
1484 pipeselwakeup(cpipe);
1485
1486 /*
1487 * If the other side is blocked, wake it up saying that
1488 * we want to close it down.
1489 */
1490 cpipe->pipe_state |= PIPE_EOF;
1491 while (cpipe->pipe_busy) {
1492 wakeup(cpipe);
1493 cpipe->pipe_state |= PIPE_WANT;
1494 pipeunlock(cpipe);
1495 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
1496 pipelock(cpipe, 0);
1497 }
1498
1499
1500 /*
1501 * Disconnect from peer, if any.
1502 */
1503 ppipe = cpipe->pipe_peer;
1504 if (ppipe->pipe_present != 0) {
1505 pipeselwakeup(ppipe);
1506
1507 ppipe->pipe_state |= PIPE_EOF;
1508 wakeup(ppipe);
1509 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0);
1510 }
1511
1512 /*
1513 * Mark this endpoint as free. Release kmem resources. We
1514 * don't mark this endpoint as unused until we've finished
1515 * doing that, or the pipe might disappear out from under
1516 * us.
1517 */
1518 PIPE_UNLOCK(cpipe);
1519 pipe_free_kmem(cpipe);
1520 PIPE_LOCK(cpipe);
1521 cpipe->pipe_present = 0;
1522 pipeunlock(cpipe);
1523 knlist_clear(&cpipe->pipe_sel.si_note, 1);
1524 knlist_destroy(&cpipe->pipe_sel.si_note);
1525
1526 /*
1527 * If both endpoints are now closed, release the memory for the
1528 * pipe pair. If not, unlock.
1529 */
1530 if (ppipe->pipe_present == 0) {
1531 PIPE_UNLOCK(cpipe);
1532 #ifdef MAC
1533 mac_destroy_pipe(pp);
1534 #endif
1535 uma_zfree(pipe_zone, cpipe->pipe_pair);
1536 } else
1537 PIPE_UNLOCK(cpipe);
1538 }
1539
1540 /*ARGSUSED*/
1541 static int
1542 pipe_kqfilter(struct file *fp, struct knote *kn)
1543 {
1544 struct pipe *cpipe;
1545
1546 cpipe = kn->kn_fp->f_data;
1547 PIPE_LOCK(cpipe);
1548 switch (kn->kn_filter) {
1549 case EVFILT_READ:
1550 kn->kn_fop = &pipe_rfiltops;
1551 break;
1552 case EVFILT_WRITE:
1553 kn->kn_fop = &pipe_wfiltops;
1554 if (!cpipe->pipe_peer->pipe_present) {
1555 /* other end of pipe has been closed */
1556 PIPE_UNLOCK(cpipe);
1557 return (EPIPE);
1558 }
1559 cpipe = cpipe->pipe_peer;
1560 break;
1561 default:
1562 PIPE_UNLOCK(cpipe);
1563 return (EINVAL);
1564 }
1565
1566 knlist_add(&cpipe->pipe_sel.si_note, kn, 1);
1567 PIPE_UNLOCK(cpipe);
1568 return (0);
1569 }
1570
1571 static void
1572 filt_pipedetach(struct knote *kn)
1573 {
1574 struct pipe *cpipe = (struct pipe *)kn->kn_fp->f_data;
1575
1576 PIPE_LOCK(cpipe);
1577 if (kn->kn_filter == EVFILT_WRITE) {
1578 if (!cpipe->pipe_peer->pipe_present) {
1579 PIPE_UNLOCK(cpipe);
1580 return;
1581 }
1582 cpipe = cpipe->pipe_peer;
1583 }
1584 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1);
1585 PIPE_UNLOCK(cpipe);
1586 }
1587
1588 /*ARGSUSED*/
1589 static int
1590 filt_piperead(struct knote *kn, long hint)
1591 {
1592 struct pipe *rpipe = kn->kn_fp->f_data;
1593 struct pipe *wpipe = rpipe->pipe_peer;
1594 int ret;
1595
1596 PIPE_LOCK(rpipe);
1597 kn->kn_data = rpipe->pipe_buffer.cnt;
1598 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
1599 kn->kn_data = rpipe->pipe_map.cnt;
1600
1601 if ((rpipe->pipe_state & PIPE_EOF) ||
1602 (!wpipe->pipe_present) || (wpipe->pipe_state & PIPE_EOF)) {
1603 kn->kn_flags |= EV_EOF;
1604 PIPE_UNLOCK(rpipe);
1605 return (1);
1606 }
1607 ret = kn->kn_data > 0;
1608 PIPE_UNLOCK(rpipe);
1609 return ret;
1610 }
1611
1612 /*ARGSUSED*/
1613 static int
1614 filt_pipewrite(struct knote *kn, long hint)
1615 {
1616 struct pipe *rpipe = kn->kn_fp->f_data;
1617 struct pipe *wpipe = rpipe->pipe_peer;
1618
1619 PIPE_LOCK(rpipe);
1620 if ((!wpipe->pipe_present) || (wpipe->pipe_state & PIPE_EOF)) {
1621 kn->kn_data = 0;
1622 kn->kn_flags |= EV_EOF;
1623 PIPE_UNLOCK(rpipe);
1624 return (1);
1625 }
1626 kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1627 if (wpipe->pipe_state & PIPE_DIRECTW)
1628 kn->kn_data = 0;
1629
1630 PIPE_UNLOCK(rpipe);
1631 return (kn->kn_data >= PIPE_BUF);
1632 }
Cache object: b7870b0285e2454149bdfc60a20ca212
|