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