1 /*-
2 * Copyright (c) 1996 John S. Dyson
3 * Copyright (c) 2012 Giovanni Trematerra
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice immediately at the beginning of the file, without modification,
11 * this list of conditions, and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Absolutely no warranty of function or purpose is made by the author
16 * John S. Dyson.
17 * 4. Modifications may be freely made to this file if the above conditions
18 * are met.
19 */
20
21 /*
22 * This file contains a high-performance replacement for the socket-based
23 * pipes scheme originally used in FreeBSD/4.4Lite. It does not support
24 * all features of sockets, but does do everything that pipes normally
25 * do.
26 */
27
28 /*
29 * This code has two modes of operation, a small write mode and a large
30 * write mode. The small write mode acts like conventional pipes with
31 * a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the
32 * "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT
33 * and PIPE_SIZE in size, the sending process pins the underlying pages in
34 * memory, and the receiving process copies directly from these pinned pages
35 * in the sending process.
36 *
37 * If the sending process receives a signal, it is possible that it will
38 * go away, and certainly its address space can change, because control
39 * is returned back to the user-mode side. In that case, the pipe code
40 * arranges to copy the buffer supplied by the user process, to a pageable
41 * kernel buffer, and the receiving process will grab the data from the
42 * pageable kernel buffer. Since signals don't happen all that often,
43 * the copy operation is normally eliminated.
44 *
45 * The constant PIPE_MINDIRECT is chosen to make sure that buffering will
46 * happen for small transfers so that the system will not spend all of
47 * its time context switching.
48 *
49 * In order to limit the resource use of pipes, two sysctls exist:
50 *
51 * kern.ipc.maxpipekva - This is a hard limit on the amount of pageable
52 * address space available to us in pipe_map. This value is normally
53 * autotuned, but may also be loader tuned.
54 *
55 * kern.ipc.pipekva - This read-only sysctl tracks the current amount of
56 * memory in use by pipes.
57 *
58 * Based on how large pipekva is relative to maxpipekva, the following
59 * will happen:
60 *
61 * 0% - 50%:
62 * New pipes are given 16K of memory backing, pipes may dynamically
63 * grow to as large as 64K where needed.
64 * 50% - 75%:
65 * New pipes are given 4K (or PAGE_SIZE) of memory backing,
66 * existing pipes may NOT grow.
67 * 75% - 100%:
68 * New pipes are given 4K (or PAGE_SIZE) of memory backing,
69 * existing pipes will be shrunk down to 4K whenever possible.
70 *
71 * Resizing may be disabled by setting kern.ipc.piperesizeallowed=0. If
72 * that is set, the only resize that will occur is the 0 -> SMALL_PIPE_SIZE
73 * resize which MUST occur for reverse-direction pipes when they are
74 * first used.
75 *
76 * Additional information about the current state of pipes may be obtained
77 * from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail,
78 * and kern.ipc.piperesizefail.
79 *
80 * Locking rules: There are two locks present here: A mutex, used via
81 * PIPE_LOCK, and a flag, used via pipelock(). All locking is done via
82 * the flag, as mutexes can not persist over uiomove. The mutex
83 * exists only to guard access to the flag, and is not in itself a
84 * locking mechanism. Also note that there is only a single mutex for
85 * both directions of a pipe.
86 *
87 * As pipelock() may have to sleep before it can acquire the flag, it
88 * is important to reread all data after a call to pipelock(); everything
89 * in the structure may have changed.
90 */
91
92 #include "opt_compat.h"
93
94 #include <sys/cdefs.h>
95 __FBSDID("$FreeBSD$");
96
97 #include <sys/param.h>
98 #include <sys/systm.h>
99 #include <sys/conf.h>
100 #include <sys/fcntl.h>
101 #include <sys/file.h>
102 #include <sys/filedesc.h>
103 #include <sys/filio.h>
104 #include <sys/kernel.h>
105 #include <sys/lock.h>
106 #include <sys/mutex.h>
107 #include <sys/ttycom.h>
108 #include <sys/stat.h>
109 #include <sys/malloc.h>
110 #include <sys/poll.h>
111 #include <sys/selinfo.h>
112 #include <sys/signalvar.h>
113 #include <sys/syscallsubr.h>
114 #include <sys/sysctl.h>
115 #include <sys/sysproto.h>
116 #include <sys/pipe.h>
117 #include <sys/proc.h>
118 #include <sys/vnode.h>
119 #include <sys/uio.h>
120 #include <sys/user.h>
121 #include <sys/event.h>
122
123 #include <security/mac/mac_framework.h>
124
125 #include <vm/vm.h>
126 #include <vm/vm_param.h>
127 #include <vm/vm_object.h>
128 #include <vm/vm_kern.h>
129 #include <vm/vm_extern.h>
130 #include <vm/pmap.h>
131 #include <vm/vm_map.h>
132 #include <vm/vm_page.h>
133 #include <vm/uma.h>
134
135 /*
136 * Use this define if you want to disable *fancy* VM things. Expect an
137 * approx 30% decrease in transfer rate. This could be useful for
138 * NetBSD or OpenBSD.
139 */
140 /* #define PIPE_NODIRECT */
141
142 #define PIPE_PEER(pipe) \
143 (((pipe)->pipe_state & PIPE_NAMED) ? (pipe) : ((pipe)->pipe_peer))
144
145 /*
146 * interfaces to the outside world
147 */
148 static fo_rdwr_t pipe_read;
149 static fo_rdwr_t pipe_write;
150 static fo_truncate_t pipe_truncate;
151 static fo_ioctl_t pipe_ioctl;
152 static fo_poll_t pipe_poll;
153 static fo_kqfilter_t pipe_kqfilter;
154 static fo_stat_t pipe_stat;
155 static fo_close_t pipe_close;
156 static fo_chmod_t pipe_chmod;
157 static fo_chown_t pipe_chown;
158 static fo_fill_kinfo_t pipe_fill_kinfo;
159
160 struct fileops pipeops = {
161 .fo_read = pipe_read,
162 .fo_write = pipe_write,
163 .fo_truncate = pipe_truncate,
164 .fo_ioctl = pipe_ioctl,
165 .fo_poll = pipe_poll,
166 .fo_kqfilter = pipe_kqfilter,
167 .fo_stat = pipe_stat,
168 .fo_close = pipe_close,
169 .fo_chmod = pipe_chmod,
170 .fo_chown = pipe_chown,
171 .fo_sendfile = invfo_sendfile,
172 .fo_fill_kinfo = pipe_fill_kinfo,
173 .fo_flags = DFLAG_PASSABLE
174 };
175
176 static void filt_pipedetach(struct knote *kn);
177 static void filt_pipedetach_notsup(struct knote *kn);
178 static int filt_pipenotsup(struct knote *kn, long hint);
179 static int filt_piperead(struct knote *kn, long hint);
180 static int filt_pipewrite(struct knote *kn, long hint);
181
182 static struct filterops pipe_nfiltops = {
183 .f_isfd = 1,
184 .f_detach = filt_pipedetach_notsup,
185 .f_event = filt_pipenotsup
186 };
187 static struct filterops pipe_rfiltops = {
188 .f_isfd = 1,
189 .f_detach = filt_pipedetach,
190 .f_event = filt_piperead
191 };
192 static struct filterops pipe_wfiltops = {
193 .f_isfd = 1,
194 .f_detach = filt_pipedetach,
195 .f_event = filt_pipewrite
196 };
197
198 /*
199 * Default pipe buffer size(s), this can be kind-of large now because pipe
200 * space is pageable. The pipe code will try to maintain locality of
201 * reference for performance reasons, so small amounts of outstanding I/O
202 * will not wipe the cache.
203 */
204 #define MINPIPESIZE (PIPE_SIZE/3)
205 #define MAXPIPESIZE (2*PIPE_SIZE/3)
206
207 static long amountpipekva;
208 static int pipefragretry;
209 static int pipeallocfail;
210 static int piperesizefail;
211 static int piperesizeallowed = 1;
212
213 SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
214 &maxpipekva, 0, "Pipe KVA limit");
215 SYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD,
216 &amountpipekva, 0, "Pipe KVA usage");
217 SYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD,
218 &pipefragretry, 0, "Pipe allocation retries due to fragmentation");
219 SYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD,
220 &pipeallocfail, 0, "Pipe allocation failures");
221 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD,
222 &piperesizefail, 0, "Pipe resize failures");
223 SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW,
224 &piperesizeallowed, 0, "Pipe resizing allowed");
225
226 static void pipeinit(void *dummy __unused);
227 static void pipeclose(struct pipe *cpipe);
228 static void pipe_free_kmem(struct pipe *cpipe);
229 static void pipe_create(struct pipe *pipe, int backing);
230 static void pipe_paircreate(struct thread *td, struct pipepair **p_pp);
231 static __inline int pipelock(struct pipe *cpipe, int catch);
232 static __inline void pipeunlock(struct pipe *cpipe);
233 #ifndef PIPE_NODIRECT
234 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio);
235 static void pipe_destroy_write_buffer(struct pipe *wpipe);
236 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio);
237 static void pipe_clone_write_buffer(struct pipe *wpipe);
238 #endif
239 static int pipespace(struct pipe *cpipe, int size);
240 static int pipespace_new(struct pipe *cpipe, int size);
241
242 static int pipe_zone_ctor(void *mem, int size, void *arg, int flags);
243 static int pipe_zone_init(void *mem, int size, int flags);
244 static void pipe_zone_fini(void *mem, int size);
245
246 static uma_zone_t pipe_zone;
247 static struct unrhdr *pipeino_unr;
248 static dev_t pipedev_ino;
249
250 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
251
252 static void
pipeinit(void * dummy __unused)253 pipeinit(void *dummy __unused)
254 {
255
256 pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair),
257 pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini,
258 UMA_ALIGN_PTR, 0);
259 KASSERT(pipe_zone != NULL, ("pipe_zone not initialized"));
260 pipeino_unr = new_unrhdr(1, INT32_MAX, NULL);
261 KASSERT(pipeino_unr != NULL, ("pipe fake inodes not initialized"));
262 pipedev_ino = devfs_alloc_cdp_inode();
263 KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized"));
264 }
265
266 static int
pipe_zone_ctor(void * mem,int size,void * arg,int flags)267 pipe_zone_ctor(void *mem, int size, void *arg, int flags)
268 {
269 struct pipepair *pp;
270 struct pipe *rpipe, *wpipe;
271
272 KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size"));
273
274 pp = (struct pipepair *)mem;
275
276 /*
277 * We zero both pipe endpoints to make sure all the kmem pointers
278 * are NULL, flag fields are zero'd, etc. We timestamp both
279 * endpoints with the same time.
280 */
281 rpipe = &pp->pp_rpipe;
282 bzero(rpipe, sizeof(*rpipe));
283 vfs_timestamp(&rpipe->pipe_ctime);
284 rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime;
285
286 wpipe = &pp->pp_wpipe;
287 bzero(wpipe, sizeof(*wpipe));
288 wpipe->pipe_ctime = rpipe->pipe_ctime;
289 wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime;
290
291 rpipe->pipe_peer = wpipe;
292 rpipe->pipe_pair = pp;
293 wpipe->pipe_peer = rpipe;
294 wpipe->pipe_pair = pp;
295
296 /*
297 * Mark both endpoints as present; they will later get free'd
298 * one at a time. When both are free'd, then the whole pair
299 * is released.
300 */
301 rpipe->pipe_present = PIPE_ACTIVE;
302 wpipe->pipe_present = PIPE_ACTIVE;
303
304 /*
305 * Eventually, the MAC Framework may initialize the label
306 * in ctor or init, but for now we do it elswhere to avoid
307 * blocking in ctor or init.
308 */
309 pp->pp_label = NULL;
310
311 return (0);
312 }
313
314 static int
pipe_zone_init(void * mem,int size,int flags)315 pipe_zone_init(void *mem, int size, int flags)
316 {
317 struct pipepair *pp;
318
319 KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size"));
320
321 pp = (struct pipepair *)mem;
322
323 mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_NEW);
324 return (0);
325 }
326
327 static void
pipe_zone_fini(void * mem,int size)328 pipe_zone_fini(void *mem, int size)
329 {
330 struct pipepair *pp;
331
332 KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size"));
333
334 pp = (struct pipepair *)mem;
335
336 mtx_destroy(&pp->pp_mtx);
337 }
338
339 static void
pipe_paircreate(struct thread * td,struct pipepair ** p_pp)340 pipe_paircreate(struct thread *td, struct pipepair **p_pp)
341 {
342 struct pipepair *pp;
343 struct pipe *rpipe, *wpipe;
344
345 *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK);
346 #ifdef MAC
347 /*
348 * The MAC label is shared between the connected endpoints. As a
349 * result mac_pipe_init() and mac_pipe_create() are called once
350 * for the pair, and not on the endpoints.
351 */
352 mac_pipe_init(pp);
353 mac_pipe_create(td->td_ucred, pp);
354 #endif
355 rpipe = &pp->pp_rpipe;
356 wpipe = &pp->pp_wpipe;
357
358 knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe));
359 knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe));
360
361 /* Only the forward direction pipe is backed by default */
362 pipe_create(rpipe, 1);
363 pipe_create(wpipe, 0);
364
365 rpipe->pipe_state |= PIPE_DIRECTOK;
366 wpipe->pipe_state |= PIPE_DIRECTOK;
367 }
368
369 void
pipe_named_ctor(struct pipe ** ppipe,struct thread * td)370 pipe_named_ctor(struct pipe **ppipe, struct thread *td)
371 {
372 struct pipepair *pp;
373
374 pipe_paircreate(td, &pp);
375 pp->pp_rpipe.pipe_state |= PIPE_NAMED;
376 *ppipe = &pp->pp_rpipe;
377 }
378
379 void
pipe_dtor(struct pipe * dpipe)380 pipe_dtor(struct pipe *dpipe)
381 {
382 struct pipe *peer;
383 ino_t ino;
384
385 ino = dpipe->pipe_ino;
386 peer = (dpipe->pipe_state & PIPE_NAMED) != 0 ? dpipe->pipe_peer : NULL;
387 funsetown(&dpipe->pipe_sigio);
388 pipeclose(dpipe);
389 if (peer != NULL) {
390 funsetown(&peer->pipe_sigio);
391 pipeclose(peer);
392 }
393 if (ino != 0 && ino != (ino_t)-1)
394 free_unr(pipeino_unr, ino);
395 }
396
397 /*
398 * The pipe system call for the DTYPE_PIPE type of pipes. If we fail, let
399 * the zone pick up the pieces via pipeclose().
400 */
401 int
kern_pipe(struct thread * td,int fildes[2],int flags,struct filecaps * fcaps1,struct filecaps * fcaps2)402 kern_pipe(struct thread *td, int fildes[2], int flags, struct filecaps *fcaps1,
403 struct filecaps *fcaps2)
404 {
405 struct file *rf, *wf;
406 struct pipe *rpipe, *wpipe;
407 struct pipepair *pp;
408 int fd, fflags, error;
409
410 pipe_paircreate(td, &pp);
411 rpipe = &pp->pp_rpipe;
412 wpipe = &pp->pp_wpipe;
413 error = falloc_caps(td, &rf, &fd, flags, fcaps1);
414 if (error) {
415 pipeclose(rpipe);
416 pipeclose(wpipe);
417 return (error);
418 }
419 /* An extra reference on `rf' has been held for us by falloc_caps(). */
420 fildes[0] = fd;
421
422 fflags = FREAD | FWRITE;
423 if ((flags & O_NONBLOCK) != 0)
424 fflags |= FNONBLOCK;
425
426 /*
427 * Warning: once we've gotten past allocation of the fd for the
428 * read-side, we can only drop the read side via fdrop() in order
429 * to avoid races against processes which manage to dup() the read
430 * side while we are blocked trying to allocate the write side.
431 */
432 finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops);
433 error = falloc_caps(td, &wf, &fd, flags, fcaps2);
434 if (error) {
435 fdclose(td, rf, fildes[0]);
436 fdrop(rf, td);
437 /* rpipe has been closed by fdrop(). */
438 pipeclose(wpipe);
439 return (error);
440 }
441 /* An extra reference on `wf' has been held for us by falloc_caps(). */
442 finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops);
443 fdrop(wf, td);
444 fildes[1] = fd;
445 fdrop(rf, td);
446
447 return (0);
448 }
449
450 #ifdef COMPAT_FREEBSD10
451 /* ARGSUSED */
452 int
freebsd10_pipe(struct thread * td,struct freebsd10_pipe_args * uap __unused)453 freebsd10_pipe(struct thread *td, struct freebsd10_pipe_args *uap __unused)
454 {
455 int error;
456 int fildes[2];
457
458 error = kern_pipe(td, fildes, 0, NULL, NULL);
459 if (error)
460 return (error);
461
462 td->td_retval[0] = fildes[0];
463 td->td_retval[1] = fildes[1];
464
465 return (0);
466 }
467 #endif
468
469 int
sys_pipe2(struct thread * td,struct pipe2_args * uap)470 sys_pipe2(struct thread *td, struct pipe2_args *uap)
471 {
472 int error, fildes[2];
473
474 if (uap->flags & ~(O_CLOEXEC | O_NONBLOCK))
475 return (EINVAL);
476 error = kern_pipe(td, fildes, uap->flags, NULL, NULL);
477 if (error)
478 return (error);
479 error = copyout(fildes, uap->fildes, 2 * sizeof(int));
480 if (error) {
481 (void)kern_close(td, fildes[0]);
482 (void)kern_close(td, fildes[1]);
483 }
484 return (error);
485 }
486
487 /*
488 * Allocate kva for pipe circular buffer, the space is pageable
489 * This routine will 'realloc' the size of a pipe safely, if it fails
490 * it will retain the old buffer.
491 * If it fails it will return ENOMEM.
492 */
493 static int
pipespace_new(cpipe,size)494 pipespace_new(cpipe, size)
495 struct pipe *cpipe;
496 int size;
497 {
498 caddr_t buffer;
499 int error, cnt, firstseg;
500 static int curfail = 0;
501 static struct timeval lastfail;
502
503 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked"));
504 KASSERT(!(cpipe->pipe_state & PIPE_DIRECTW),
505 ("pipespace: resize of direct writes not allowed"));
506 retry:
507 cnt = cpipe->pipe_buffer.cnt;
508 if (cnt > size)
509 size = cnt;
510
511 size = round_page(size);
512 buffer = (caddr_t) vm_map_min(pipe_map);
513
514 error = vm_map_find(pipe_map, NULL, 0, (vm_offset_t *)&buffer, size, 0,
515 VMFS_ANY_SPACE, VM_PROT_RW, VM_PROT_RW, 0);
516 if (error != KERN_SUCCESS) {
517 if ((cpipe->pipe_buffer.buffer == NULL) &&
518 (size > SMALL_PIPE_SIZE)) {
519 size = SMALL_PIPE_SIZE;
520 pipefragretry++;
521 goto retry;
522 }
523 if (cpipe->pipe_buffer.buffer == NULL) {
524 pipeallocfail++;
525 if (ppsratecheck(&lastfail, &curfail, 1))
526 printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n");
527 } else {
528 piperesizefail++;
529 }
530 return (ENOMEM);
531 }
532
533 /* copy data, then free old resources if we're resizing */
534 if (cnt > 0) {
535 if (cpipe->pipe_buffer.in <= cpipe->pipe_buffer.out) {
536 firstseg = cpipe->pipe_buffer.size - cpipe->pipe_buffer.out;
537 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
538 buffer, firstseg);
539 if ((cnt - firstseg) > 0)
540 bcopy(cpipe->pipe_buffer.buffer, &buffer[firstseg],
541 cpipe->pipe_buffer.in);
542 } else {
543 bcopy(&cpipe->pipe_buffer.buffer[cpipe->pipe_buffer.out],
544 buffer, cnt);
545 }
546 }
547 pipe_free_kmem(cpipe);
548 cpipe->pipe_buffer.buffer = buffer;
549 cpipe->pipe_buffer.size = size;
550 cpipe->pipe_buffer.in = cnt;
551 cpipe->pipe_buffer.out = 0;
552 cpipe->pipe_buffer.cnt = cnt;
553 atomic_add_long(&amountpipekva, cpipe->pipe_buffer.size);
554 return (0);
555 }
556
557 /*
558 * Wrapper for pipespace_new() that performs locking assertions.
559 */
560 static int
pipespace(cpipe,size)561 pipespace(cpipe, size)
562 struct pipe *cpipe;
563 int size;
564 {
565
566 KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
567 ("Unlocked pipe passed to pipespace"));
568 return (pipespace_new(cpipe, size));
569 }
570
571 /*
572 * lock a pipe for I/O, blocking other access
573 */
574 static __inline int
pipelock(cpipe,catch)575 pipelock(cpipe, catch)
576 struct pipe *cpipe;
577 int catch;
578 {
579 int error;
580
581 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
582 while (cpipe->pipe_state & PIPE_LOCKFL) {
583 cpipe->pipe_state |= PIPE_LWANT;
584 error = msleep(cpipe, PIPE_MTX(cpipe),
585 catch ? (PRIBIO | PCATCH) : PRIBIO,
586 "pipelk", 0);
587 if (error != 0)
588 return (error);
589 }
590 cpipe->pipe_state |= PIPE_LOCKFL;
591 return (0);
592 }
593
594 /*
595 * unlock a pipe I/O lock
596 */
597 static __inline void
pipeunlock(cpipe)598 pipeunlock(cpipe)
599 struct pipe *cpipe;
600 {
601
602 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
603 KASSERT(cpipe->pipe_state & PIPE_LOCKFL,
604 ("Unlocked pipe passed to pipeunlock"));
605 cpipe->pipe_state &= ~PIPE_LOCKFL;
606 if (cpipe->pipe_state & PIPE_LWANT) {
607 cpipe->pipe_state &= ~PIPE_LWANT;
608 wakeup(cpipe);
609 }
610 }
611
612 void
pipeselwakeup(cpipe)613 pipeselwakeup(cpipe)
614 struct pipe *cpipe;
615 {
616
617 PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
618 if (cpipe->pipe_state & PIPE_SEL) {
619 selwakeuppri(&cpipe->pipe_sel, PSOCK);
620 if (!SEL_WAITING(&cpipe->pipe_sel))
621 cpipe->pipe_state &= ~PIPE_SEL;
622 }
623 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
624 pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
625 KNOTE_LOCKED(&cpipe->pipe_sel.si_note, 0);
626 }
627
628 /*
629 * Initialize and allocate VM and memory for pipe. The structure
630 * will start out zero'd from the ctor, so we just manage the kmem.
631 */
632 static void
pipe_create(pipe,backing)633 pipe_create(pipe, backing)
634 struct pipe *pipe;
635 int backing;
636 {
637
638 if (backing) {
639 /*
640 * Note that these functions can fail if pipe map is exhausted
641 * (as a result of too many pipes created), but we ignore the
642 * error as it is not fatal and could be provoked by
643 * unprivileged users. The only consequence is worse performance
644 * with given pipe.
645 */
646 if (amountpipekva > maxpipekva / 2)
647 (void)pipespace_new(pipe, SMALL_PIPE_SIZE);
648 else
649 (void)pipespace_new(pipe, PIPE_SIZE);
650 }
651
652 pipe->pipe_ino = -1;
653 }
654
655 /* ARGSUSED */
656 static int
pipe_read(fp,uio,active_cred,flags,td)657 pipe_read(fp, uio, active_cred, flags, td)
658 struct file *fp;
659 struct uio *uio;
660 struct ucred *active_cred;
661 struct thread *td;
662 int flags;
663 {
664 struct pipe *rpipe;
665 int error;
666 int nread = 0;
667 int size;
668
669 rpipe = fp->f_data;
670 PIPE_LOCK(rpipe);
671 ++rpipe->pipe_busy;
672 error = pipelock(rpipe, 1);
673 if (error)
674 goto unlocked_error;
675
676 #ifdef MAC
677 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair);
678 if (error)
679 goto locked_error;
680 #endif
681 if (amountpipekva > (3 * maxpipekva) / 4) {
682 if (!(rpipe->pipe_state & PIPE_DIRECTW) &&
683 (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
684 (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
685 (piperesizeallowed == 1)) {
686 PIPE_UNLOCK(rpipe);
687 pipespace(rpipe, SMALL_PIPE_SIZE);
688 PIPE_LOCK(rpipe);
689 }
690 }
691
692 while (uio->uio_resid) {
693 /*
694 * normal pipe buffer receive
695 */
696 if (rpipe->pipe_buffer.cnt > 0) {
697 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
698 if (size > rpipe->pipe_buffer.cnt)
699 size = rpipe->pipe_buffer.cnt;
700 if (size > uio->uio_resid)
701 size = uio->uio_resid;
702
703 PIPE_UNLOCK(rpipe);
704 error = uiomove(
705 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
706 size, uio);
707 PIPE_LOCK(rpipe);
708 if (error)
709 break;
710
711 rpipe->pipe_buffer.out += size;
712 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
713 rpipe->pipe_buffer.out = 0;
714
715 rpipe->pipe_buffer.cnt -= size;
716
717 /*
718 * If there is no more to read in the pipe, reset
719 * its pointers to the beginning. This improves
720 * cache hit stats.
721 */
722 if (rpipe->pipe_buffer.cnt == 0) {
723 rpipe->pipe_buffer.in = 0;
724 rpipe->pipe_buffer.out = 0;
725 }
726 nread += size;
727 #ifndef PIPE_NODIRECT
728 /*
729 * Direct copy, bypassing a kernel buffer.
730 */
731 } else if ((size = rpipe->pipe_map.cnt) &&
732 (rpipe->pipe_state & PIPE_DIRECTW)) {
733 if (size > uio->uio_resid)
734 size = (u_int) uio->uio_resid;
735
736 PIPE_UNLOCK(rpipe);
737 error = uiomove_fromphys(rpipe->pipe_map.ms,
738 rpipe->pipe_map.pos, size, uio);
739 PIPE_LOCK(rpipe);
740 if (error)
741 break;
742 nread += size;
743 rpipe->pipe_map.pos += size;
744 rpipe->pipe_map.cnt -= size;
745 if (rpipe->pipe_map.cnt == 0) {
746 rpipe->pipe_state &= ~PIPE_WANTW;
747 wakeup(rpipe);
748 }
749 #endif
750 } else {
751 /*
752 * detect EOF condition
753 * read returns 0 on EOF, no need to set error
754 */
755 if (rpipe->pipe_state & PIPE_EOF)
756 break;
757
758 /*
759 * If the "write-side" has been blocked, wake it up now.
760 */
761 if (rpipe->pipe_state & PIPE_WANTW) {
762 rpipe->pipe_state &= ~PIPE_WANTW;
763 wakeup(rpipe);
764 }
765
766 /*
767 * Break if some data was read.
768 */
769 if (nread > 0)
770 break;
771
772 /*
773 * Unlock the pipe buffer for our remaining processing.
774 * We will either break out with an error or we will
775 * sleep and relock to loop.
776 */
777 pipeunlock(rpipe);
778
779 /*
780 * Handle non-blocking mode operation or
781 * wait for more data.
782 */
783 if (fp->f_flag & FNONBLOCK) {
784 error = EAGAIN;
785 } else {
786 rpipe->pipe_state |= PIPE_WANTR;
787 if ((error = msleep(rpipe, PIPE_MTX(rpipe),
788 PRIBIO | PCATCH,
789 "piperd", 0)) == 0)
790 error = pipelock(rpipe, 1);
791 }
792 if (error)
793 goto unlocked_error;
794 }
795 }
796 #ifdef MAC
797 locked_error:
798 #endif
799 pipeunlock(rpipe);
800
801 /* XXX: should probably do this before getting any locks. */
802 if (error == 0)
803 vfs_timestamp(&rpipe->pipe_atime);
804 unlocked_error:
805 --rpipe->pipe_busy;
806
807 /*
808 * PIPE_WANT processing only makes sense if pipe_busy is 0.
809 */
810 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
811 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
812 wakeup(rpipe);
813 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
814 /*
815 * Handle write blocking hysteresis.
816 */
817 if (rpipe->pipe_state & PIPE_WANTW) {
818 rpipe->pipe_state &= ~PIPE_WANTW;
819 wakeup(rpipe);
820 }
821 }
822
823 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
824 pipeselwakeup(rpipe);
825
826 PIPE_UNLOCK(rpipe);
827 return (error);
828 }
829
830 #ifndef PIPE_NODIRECT
831 /*
832 * Map the sending processes' buffer into kernel space and wire it.
833 * This is similar to a physical write operation.
834 */
835 static int
pipe_build_write_buffer(wpipe,uio)836 pipe_build_write_buffer(wpipe, uio)
837 struct pipe *wpipe;
838 struct uio *uio;
839 {
840 u_int size;
841 int i;
842
843 PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED);
844 KASSERT(wpipe->pipe_state & PIPE_DIRECTW,
845 ("Clone attempt on non-direct write pipe!"));
846
847 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size)
848 size = wpipe->pipe_buffer.size;
849 else
850 size = uio->uio_iov->iov_len;
851
852 if ((i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
853 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ,
854 wpipe->pipe_map.ms, PIPENPAGES)) < 0)
855 return (EFAULT);
856
857 /*
858 * set up the control block
859 */
860 wpipe->pipe_map.npages = i;
861 wpipe->pipe_map.pos =
862 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK;
863 wpipe->pipe_map.cnt = size;
864
865 /*
866 * and update the uio data
867 */
868
869 uio->uio_iov->iov_len -= size;
870 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size;
871 if (uio->uio_iov->iov_len == 0)
872 uio->uio_iov++;
873 uio->uio_resid -= size;
874 uio->uio_offset += size;
875 return (0);
876 }
877
878 /*
879 * Unwire the process buffer.
880 */
881 static void
pipe_destroy_write_buffer(wpipe)882 pipe_destroy_write_buffer(wpipe)
883 struct pipe *wpipe;
884 {
885
886 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
887 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0,
888 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe));
889
890 wpipe->pipe_state &= ~PIPE_DIRECTW;
891 vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages);
892 wpipe->pipe_map.npages = 0;
893 }
894
895 /*
896 * In the case of a signal, the writing process might go away. This
897 * code copies the data into the circular buffer so that the source
898 * pages can be freed without loss of data.
899 */
900 static void
pipe_clone_write_buffer(wpipe)901 pipe_clone_write_buffer(wpipe)
902 struct pipe *wpipe;
903 {
904 struct uio uio;
905 struct iovec iov;
906 int size;
907 int pos;
908
909 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
910 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0,
911 ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe));
912
913 size = wpipe->pipe_map.cnt;
914 pos = wpipe->pipe_map.pos;
915
916 wpipe->pipe_buffer.in = size;
917 wpipe->pipe_buffer.out = 0;
918 wpipe->pipe_buffer.cnt = size;
919
920 PIPE_UNLOCK(wpipe);
921 iov.iov_base = wpipe->pipe_buffer.buffer;
922 iov.iov_len = size;
923 uio.uio_iov = &iov;
924 uio.uio_iovcnt = 1;
925 uio.uio_offset = 0;
926 uio.uio_resid = size;
927 uio.uio_segflg = UIO_SYSSPACE;
928 uio.uio_rw = UIO_READ;
929 uio.uio_td = curthread;
930 uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio);
931 PIPE_LOCK(wpipe);
932 pipe_destroy_write_buffer(wpipe);
933 }
934
935 /*
936 * This implements the pipe buffer write mechanism. Note that only
937 * a direct write OR a normal pipe write can be pending at any given time.
938 * If there are any characters in the pipe buffer, the direct write will
939 * be deferred until the receiving process grabs all of the bytes from
940 * the pipe buffer. Then the direct mapping write is set-up.
941 */
942 static int
pipe_direct_write(wpipe,uio)943 pipe_direct_write(wpipe, uio)
944 struct pipe *wpipe;
945 struct uio *uio;
946 {
947 int error;
948
949 retry:
950 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
951 error = pipelock(wpipe, 1);
952 if (error != 0)
953 goto error1;
954 if ((wpipe->pipe_state & PIPE_EOF) != 0) {
955 error = EPIPE;
956 pipeunlock(wpipe);
957 goto error1;
958 }
959 if (wpipe->pipe_state & PIPE_DIRECTW) {
960 if (wpipe->pipe_state & PIPE_WANTR) {
961 wpipe->pipe_state &= ~PIPE_WANTR;
962 wakeup(wpipe);
963 }
964 pipeselwakeup(wpipe);
965 wpipe->pipe_state |= PIPE_WANTW;
966 pipeunlock(wpipe);
967 error = msleep(wpipe, PIPE_MTX(wpipe),
968 PRIBIO | PCATCH, "pipdww", 0);
969 if (error)
970 goto error1;
971 else
972 goto retry;
973 }
974 wpipe->pipe_map.cnt = 0; /* transfer not ready yet */
975 if (wpipe->pipe_buffer.cnt > 0) {
976 if (wpipe->pipe_state & PIPE_WANTR) {
977 wpipe->pipe_state &= ~PIPE_WANTR;
978 wakeup(wpipe);
979 }
980 pipeselwakeup(wpipe);
981 wpipe->pipe_state |= PIPE_WANTW;
982 pipeunlock(wpipe);
983 error = msleep(wpipe, PIPE_MTX(wpipe),
984 PRIBIO | PCATCH, "pipdwc", 0);
985 if (error)
986 goto error1;
987 else
988 goto retry;
989 }
990
991 wpipe->pipe_state |= PIPE_DIRECTW;
992
993 PIPE_UNLOCK(wpipe);
994 error = pipe_build_write_buffer(wpipe, uio);
995 PIPE_LOCK(wpipe);
996 if (error) {
997 wpipe->pipe_state &= ~PIPE_DIRECTW;
998 pipeunlock(wpipe);
999 goto error1;
1000 }
1001
1002 while (wpipe->pipe_map.cnt != 0) {
1003 if (wpipe->pipe_state & PIPE_EOF) {
1004 pipe_destroy_write_buffer(wpipe);
1005 pipeselwakeup(wpipe);
1006 pipeunlock(wpipe);
1007 error = EPIPE;
1008 goto error1;
1009 }
1010 if (wpipe->pipe_state & PIPE_WANTR) {
1011 wpipe->pipe_state &= ~PIPE_WANTR;
1012 wakeup(wpipe);
1013 }
1014 pipeselwakeup(wpipe);
1015 wpipe->pipe_state |= PIPE_WANTW;
1016 pipeunlock(wpipe);
1017 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
1018 "pipdwt", 0);
1019 pipelock(wpipe, 0);
1020 if (error != 0)
1021 break;
1022 }
1023
1024 if (wpipe->pipe_state & PIPE_EOF)
1025 error = EPIPE;
1026 if (error == EINTR || error == ERESTART)
1027 pipe_clone_write_buffer(wpipe);
1028 else
1029 pipe_destroy_write_buffer(wpipe);
1030 pipeunlock(wpipe);
1031 KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0,
1032 ("pipe %p leaked PIPE_DIRECTW", wpipe));
1033 return (error);
1034
1035 error1:
1036 wakeup(wpipe);
1037 return (error);
1038 }
1039 #endif
1040
1041 static int
pipe_write(fp,uio,active_cred,flags,td)1042 pipe_write(fp, uio, active_cred, flags, td)
1043 struct file *fp;
1044 struct uio *uio;
1045 struct ucred *active_cred;
1046 struct thread *td;
1047 int flags;
1048 {
1049 int error = 0;
1050 int desiredsize;
1051 ssize_t orig_resid;
1052 struct pipe *wpipe, *rpipe;
1053
1054 rpipe = fp->f_data;
1055 wpipe = PIPE_PEER(rpipe);
1056 PIPE_LOCK(rpipe);
1057 error = pipelock(wpipe, 1);
1058 if (error) {
1059 PIPE_UNLOCK(rpipe);
1060 return (error);
1061 }
1062 /*
1063 * detect loss of pipe read side, issue SIGPIPE if lost.
1064 */
1065 if (wpipe->pipe_present != PIPE_ACTIVE ||
1066 (wpipe->pipe_state & PIPE_EOF)) {
1067 pipeunlock(wpipe);
1068 PIPE_UNLOCK(rpipe);
1069 return (EPIPE);
1070 }
1071 #ifdef MAC
1072 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair);
1073 if (error) {
1074 pipeunlock(wpipe);
1075 PIPE_UNLOCK(rpipe);
1076 return (error);
1077 }
1078 #endif
1079 ++wpipe->pipe_busy;
1080
1081 /* Choose a larger size if it's advantageous */
1082 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size);
1083 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) {
1084 if (piperesizeallowed != 1)
1085 break;
1086 if (amountpipekva > maxpipekva / 2)
1087 break;
1088 if (desiredsize == BIG_PIPE_SIZE)
1089 break;
1090 desiredsize = desiredsize * 2;
1091 }
1092
1093 /* Choose a smaller size if we're in a OOM situation */
1094 if ((amountpipekva > (3 * maxpipekva) / 4) &&
1095 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) &&
1096 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) &&
1097 (piperesizeallowed == 1))
1098 desiredsize = SMALL_PIPE_SIZE;
1099
1100 /* Resize if the above determined that a new size was necessary */
1101 if ((desiredsize != wpipe->pipe_buffer.size) &&
1102 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) {
1103 PIPE_UNLOCK(wpipe);
1104 pipespace(wpipe, desiredsize);
1105 PIPE_LOCK(wpipe);
1106 }
1107 if (wpipe->pipe_buffer.size == 0) {
1108 /*
1109 * This can only happen for reverse direction use of pipes
1110 * in a complete OOM situation.
1111 */
1112 error = ENOMEM;
1113 --wpipe->pipe_busy;
1114 pipeunlock(wpipe);
1115 PIPE_UNLOCK(wpipe);
1116 return (error);
1117 }
1118
1119 pipeunlock(wpipe);
1120
1121 orig_resid = uio->uio_resid;
1122
1123 while (uio->uio_resid) {
1124 int space;
1125
1126 pipelock(wpipe, 0);
1127 if (wpipe->pipe_state & PIPE_EOF) {
1128 pipeunlock(wpipe);
1129 error = EPIPE;
1130 break;
1131 }
1132 #ifndef PIPE_NODIRECT
1133 /*
1134 * If the transfer is large, we can gain performance if
1135 * we do process-to-process copies directly.
1136 * If the write is non-blocking, we don't use the
1137 * direct write mechanism.
1138 *
1139 * The direct write mechanism will detect the reader going
1140 * away on us.
1141 */
1142 if (uio->uio_segflg == UIO_USERSPACE &&
1143 uio->uio_iov->iov_len >= PIPE_MINDIRECT &&
1144 wpipe->pipe_buffer.size >= PIPE_MINDIRECT &&
1145 (fp->f_flag & FNONBLOCK) == 0) {
1146 pipeunlock(wpipe);
1147 error = pipe_direct_write(wpipe, uio);
1148 if (error)
1149 break;
1150 continue;
1151 }
1152 #endif
1153
1154 /*
1155 * Pipe buffered writes cannot be coincidental with
1156 * direct writes. We wait until the currently executing
1157 * direct write is completed before we start filling the
1158 * pipe buffer. We break out if a signal occurs or the
1159 * reader goes away.
1160 */
1161 if (wpipe->pipe_state & PIPE_DIRECTW) {
1162 if (wpipe->pipe_state & PIPE_WANTR) {
1163 wpipe->pipe_state &= ~PIPE_WANTR;
1164 wakeup(wpipe);
1165 }
1166 pipeselwakeup(wpipe);
1167 wpipe->pipe_state |= PIPE_WANTW;
1168 pipeunlock(wpipe);
1169 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH,
1170 "pipbww", 0);
1171 if (error)
1172 break;
1173 else
1174 continue;
1175 }
1176
1177 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1178
1179 /* Writes of size <= PIPE_BUF must be atomic. */
1180 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
1181 space = 0;
1182
1183 if (space > 0) {
1184 int size; /* Transfer size */
1185 int segsize; /* first segment to transfer */
1186
1187 /*
1188 * Transfer size is minimum of uio transfer
1189 * and free space in pipe buffer.
1190 */
1191 if (space > uio->uio_resid)
1192 size = uio->uio_resid;
1193 else
1194 size = space;
1195 /*
1196 * First segment to transfer is minimum of
1197 * transfer size and contiguous space in
1198 * pipe buffer. If first segment to transfer
1199 * is less than the transfer size, we've got
1200 * a wraparound in the buffer.
1201 */
1202 segsize = wpipe->pipe_buffer.size -
1203 wpipe->pipe_buffer.in;
1204 if (segsize > size)
1205 segsize = size;
1206
1207 /* Transfer first segment */
1208
1209 PIPE_UNLOCK(rpipe);
1210 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
1211 segsize, uio);
1212 PIPE_LOCK(rpipe);
1213
1214 if (error == 0 && segsize < size) {
1215 KASSERT(wpipe->pipe_buffer.in + segsize ==
1216 wpipe->pipe_buffer.size,
1217 ("Pipe buffer wraparound disappeared"));
1218 /*
1219 * Transfer remaining part now, to
1220 * support atomic writes. Wraparound
1221 * happened.
1222 */
1223
1224 PIPE_UNLOCK(rpipe);
1225 error = uiomove(
1226 &wpipe->pipe_buffer.buffer[0],
1227 size - segsize, uio);
1228 PIPE_LOCK(rpipe);
1229 }
1230 if (error == 0) {
1231 wpipe->pipe_buffer.in += size;
1232 if (wpipe->pipe_buffer.in >=
1233 wpipe->pipe_buffer.size) {
1234 KASSERT(wpipe->pipe_buffer.in ==
1235 size - segsize +
1236 wpipe->pipe_buffer.size,
1237 ("Expected wraparound bad"));
1238 wpipe->pipe_buffer.in = size - segsize;
1239 }
1240
1241 wpipe->pipe_buffer.cnt += size;
1242 KASSERT(wpipe->pipe_buffer.cnt <=
1243 wpipe->pipe_buffer.size,
1244 ("Pipe buffer overflow"));
1245 }
1246 pipeunlock(wpipe);
1247 if (error != 0)
1248 break;
1249 } else {
1250 /*
1251 * If the "read-side" has been blocked, wake it up now.
1252 */
1253 if (wpipe->pipe_state & PIPE_WANTR) {
1254 wpipe->pipe_state &= ~PIPE_WANTR;
1255 wakeup(wpipe);
1256 }
1257
1258 /*
1259 * don't block on non-blocking I/O
1260 */
1261 if (fp->f_flag & FNONBLOCK) {
1262 error = EAGAIN;
1263 pipeunlock(wpipe);
1264 break;
1265 }
1266
1267 /*
1268 * We have no more space and have something to offer,
1269 * wake up select/poll.
1270 */
1271 pipeselwakeup(wpipe);
1272
1273 wpipe->pipe_state |= PIPE_WANTW;
1274 pipeunlock(wpipe);
1275 error = msleep(wpipe, PIPE_MTX(rpipe),
1276 PRIBIO | PCATCH, "pipewr", 0);
1277 if (error != 0)
1278 break;
1279 }
1280 }
1281
1282 pipelock(wpipe, 0);
1283 --wpipe->pipe_busy;
1284
1285 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1286 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1287 wakeup(wpipe);
1288 } else if (wpipe->pipe_buffer.cnt > 0) {
1289 /*
1290 * If we have put any characters in the buffer, we wake up
1291 * the reader.
1292 */
1293 if (wpipe->pipe_state & PIPE_WANTR) {
1294 wpipe->pipe_state &= ~PIPE_WANTR;
1295 wakeup(wpipe);
1296 }
1297 }
1298
1299 /*
1300 * Don't return EPIPE if any byte was written.
1301 * EINTR and other interrupts are handled by generic I/O layer.
1302 * Do not pretend that I/O succeeded for obvious user error
1303 * like EFAULT.
1304 */
1305 if (uio->uio_resid != orig_resid && error == EPIPE)
1306 error = 0;
1307
1308 if (error == 0)
1309 vfs_timestamp(&wpipe->pipe_mtime);
1310
1311 /*
1312 * We have something to offer,
1313 * wake up select/poll.
1314 */
1315 if (wpipe->pipe_buffer.cnt)
1316 pipeselwakeup(wpipe);
1317
1318 pipeunlock(wpipe);
1319 PIPE_UNLOCK(rpipe);
1320 return (error);
1321 }
1322
1323 /* ARGSUSED */
1324 static int
pipe_truncate(fp,length,active_cred,td)1325 pipe_truncate(fp, length, active_cred, td)
1326 struct file *fp;
1327 off_t length;
1328 struct ucred *active_cred;
1329 struct thread *td;
1330 {
1331 struct pipe *cpipe;
1332 int error;
1333
1334 cpipe = fp->f_data;
1335 if (cpipe->pipe_state & PIPE_NAMED)
1336 error = vnops.fo_truncate(fp, length, active_cred, td);
1337 else
1338 error = invfo_truncate(fp, length, active_cred, td);
1339 return (error);
1340 }
1341
1342 /*
1343 * we implement a very minimal set of ioctls for compatibility with sockets.
1344 */
1345 static int
pipe_ioctl(fp,cmd,data,active_cred,td)1346 pipe_ioctl(fp, cmd, data, active_cred, td)
1347 struct file *fp;
1348 u_long cmd;
1349 void *data;
1350 struct ucred *active_cred;
1351 struct thread *td;
1352 {
1353 struct pipe *mpipe = fp->f_data;
1354 int error;
1355
1356 PIPE_LOCK(mpipe);
1357
1358 #ifdef MAC
1359 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data);
1360 if (error) {
1361 PIPE_UNLOCK(mpipe);
1362 return (error);
1363 }
1364 #endif
1365
1366 error = 0;
1367 switch (cmd) {
1368
1369 case FIONBIO:
1370 break;
1371
1372 case FIOASYNC:
1373 if (*(int *)data) {
1374 mpipe->pipe_state |= PIPE_ASYNC;
1375 } else {
1376 mpipe->pipe_state &= ~PIPE_ASYNC;
1377 }
1378 break;
1379
1380 case FIONREAD:
1381 if (!(fp->f_flag & FREAD)) {
1382 *(int *)data = 0;
1383 PIPE_UNLOCK(mpipe);
1384 return (0);
1385 }
1386 if (mpipe->pipe_state & PIPE_DIRECTW)
1387 *(int *)data = mpipe->pipe_map.cnt;
1388 else
1389 *(int *)data = mpipe->pipe_buffer.cnt;
1390 break;
1391
1392 case FIOSETOWN:
1393 PIPE_UNLOCK(mpipe);
1394 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
1395 goto out_unlocked;
1396
1397 case FIOGETOWN:
1398 *(int *)data = fgetown(&mpipe->pipe_sigio);
1399 break;
1400
1401 /* This is deprecated, FIOSETOWN should be used instead. */
1402 case TIOCSPGRP:
1403 PIPE_UNLOCK(mpipe);
1404 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
1405 goto out_unlocked;
1406
1407 /* This is deprecated, FIOGETOWN should be used instead. */
1408 case TIOCGPGRP:
1409 *(int *)data = -fgetown(&mpipe->pipe_sigio);
1410 break;
1411
1412 default:
1413 error = ENOTTY;
1414 break;
1415 }
1416 PIPE_UNLOCK(mpipe);
1417 out_unlocked:
1418 return (error);
1419 }
1420
1421 static int
pipe_poll(fp,events,active_cred,td)1422 pipe_poll(fp, events, active_cred, td)
1423 struct file *fp;
1424 int events;
1425 struct ucred *active_cred;
1426 struct thread *td;
1427 {
1428 struct pipe *rpipe;
1429 struct pipe *wpipe;
1430 int levents, revents;
1431 #ifdef MAC
1432 int error;
1433 #endif
1434
1435 revents = 0;
1436 rpipe = fp->f_data;
1437 wpipe = PIPE_PEER(rpipe);
1438 PIPE_LOCK(rpipe);
1439 #ifdef MAC
1440 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair);
1441 if (error)
1442 goto locked_error;
1443 #endif
1444 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM))
1445 if ((rpipe->pipe_state & PIPE_DIRECTW) ||
1446 (rpipe->pipe_buffer.cnt > 0))
1447 revents |= events & (POLLIN | POLLRDNORM);
1448
1449 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM))
1450 if (wpipe->pipe_present != PIPE_ACTIVE ||
1451 (wpipe->pipe_state & PIPE_EOF) ||
1452 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
1453 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF ||
1454 wpipe->pipe_buffer.size == 0)))
1455 revents |= events & (POLLOUT | POLLWRNORM);
1456
1457 levents = events &
1458 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND);
1459 if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents &&
1460 fp->f_seqcount == rpipe->pipe_wgen)
1461 events |= POLLINIGNEOF;
1462
1463 if ((events & POLLINIGNEOF) == 0) {
1464 if (rpipe->pipe_state & PIPE_EOF) {
1465 revents |= (events & (POLLIN | POLLRDNORM));
1466 if (wpipe->pipe_present != PIPE_ACTIVE ||
1467 (wpipe->pipe_state & PIPE_EOF))
1468 revents |= POLLHUP;
1469 }
1470 }
1471
1472 if (revents == 0) {
1473 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) {
1474 selrecord(td, &rpipe->pipe_sel);
1475 if (SEL_WAITING(&rpipe->pipe_sel))
1476 rpipe->pipe_state |= PIPE_SEL;
1477 }
1478
1479 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) {
1480 selrecord(td, &wpipe->pipe_sel);
1481 if (SEL_WAITING(&wpipe->pipe_sel))
1482 wpipe->pipe_state |= PIPE_SEL;
1483 }
1484 }
1485 #ifdef MAC
1486 locked_error:
1487 #endif
1488 PIPE_UNLOCK(rpipe);
1489
1490 return (revents);
1491 }
1492
1493 /*
1494 * We shouldn't need locks here as we're doing a read and this should
1495 * be a natural race.
1496 */
1497 static int
pipe_stat(fp,ub,active_cred,td)1498 pipe_stat(fp, ub, active_cred, td)
1499 struct file *fp;
1500 struct stat *ub;
1501 struct ucred *active_cred;
1502 struct thread *td;
1503 {
1504 struct pipe *pipe;
1505 int new_unr;
1506 #ifdef MAC
1507 int error;
1508 #endif
1509
1510 pipe = fp->f_data;
1511 PIPE_LOCK(pipe);
1512 #ifdef MAC
1513 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair);
1514 if (error) {
1515 PIPE_UNLOCK(pipe);
1516 return (error);
1517 }
1518 #endif
1519
1520 /* For named pipes ask the underlying filesystem. */
1521 if (pipe->pipe_state & PIPE_NAMED) {
1522 PIPE_UNLOCK(pipe);
1523 return (vnops.fo_stat(fp, ub, active_cred, td));
1524 }
1525
1526 /*
1527 * Lazily allocate an inode number for the pipe. Most pipe
1528 * users do not call fstat(2) on the pipe, which means that
1529 * postponing the inode allocation until it is must be
1530 * returned to userland is useful. If alloc_unr failed,
1531 * assign st_ino zero instead of returning an error.
1532 * Special pipe_ino values:
1533 * -1 - not yet initialized;
1534 * 0 - alloc_unr failed, return 0 as st_ino forever.
1535 */
1536 if (pipe->pipe_ino == (ino_t)-1) {
1537 new_unr = alloc_unr(pipeino_unr);
1538 if (new_unr != -1)
1539 pipe->pipe_ino = new_unr;
1540 else
1541 pipe->pipe_ino = 0;
1542 }
1543 PIPE_UNLOCK(pipe);
1544
1545 bzero(ub, sizeof(*ub));
1546 ub->st_mode = S_IFIFO;
1547 ub->st_blksize = PAGE_SIZE;
1548 if (pipe->pipe_state & PIPE_DIRECTW)
1549 ub->st_size = pipe->pipe_map.cnt;
1550 else
1551 ub->st_size = pipe->pipe_buffer.cnt;
1552 ub->st_blocks = howmany(ub->st_size, ub->st_blksize);
1553 ub->st_atim = pipe->pipe_atime;
1554 ub->st_mtim = pipe->pipe_mtime;
1555 ub->st_ctim = pipe->pipe_ctime;
1556 ub->st_uid = fp->f_cred->cr_uid;
1557 ub->st_gid = fp->f_cred->cr_gid;
1558 ub->st_dev = pipedev_ino;
1559 ub->st_ino = pipe->pipe_ino;
1560 /*
1561 * Left as 0: st_nlink, st_rdev, st_flags, st_gen.
1562 */
1563 return (0);
1564 }
1565
1566 /* ARGSUSED */
1567 static int
pipe_close(fp,td)1568 pipe_close(fp, td)
1569 struct file *fp;
1570 struct thread *td;
1571 {
1572
1573 if (fp->f_vnode != NULL)
1574 return vnops.fo_close(fp, td);
1575 fp->f_ops = &badfileops;
1576 pipe_dtor(fp->f_data);
1577 fp->f_data = NULL;
1578 return (0);
1579 }
1580
1581 static int
pipe_chmod(struct file * fp,mode_t mode,struct ucred * active_cred,struct thread * td)1582 pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td)
1583 {
1584 struct pipe *cpipe;
1585 int error;
1586
1587 cpipe = fp->f_data;
1588 if (cpipe->pipe_state & PIPE_NAMED)
1589 error = vn_chmod(fp, mode, active_cred, td);
1590 else
1591 error = invfo_chmod(fp, mode, active_cred, td);
1592 return (error);
1593 }
1594
1595 static int
pipe_chown(fp,uid,gid,active_cred,td)1596 pipe_chown(fp, uid, gid, active_cred, td)
1597 struct file *fp;
1598 uid_t uid;
1599 gid_t gid;
1600 struct ucred *active_cred;
1601 struct thread *td;
1602 {
1603 struct pipe *cpipe;
1604 int error;
1605
1606 cpipe = fp->f_data;
1607 if (cpipe->pipe_state & PIPE_NAMED)
1608 error = vn_chown(fp, uid, gid, active_cred, td);
1609 else
1610 error = invfo_chown(fp, uid, gid, active_cred, td);
1611 return (error);
1612 }
1613
1614 static int
pipe_fill_kinfo(struct file * fp,struct kinfo_file * kif,struct filedesc * fdp)1615 pipe_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
1616 {
1617 struct pipe *pi;
1618
1619 if (fp->f_type == DTYPE_FIFO)
1620 return (vn_fill_kinfo(fp, kif, fdp));
1621 kif->kf_type = KF_TYPE_PIPE;
1622 pi = fp->f_data;
1623 kif->kf_un.kf_pipe.kf_pipe_addr = (uintptr_t)pi;
1624 kif->kf_un.kf_pipe.kf_pipe_peer = (uintptr_t)pi->pipe_peer;
1625 kif->kf_un.kf_pipe.kf_pipe_buffer_cnt = pi->pipe_buffer.cnt;
1626 return (0);
1627 }
1628
1629 static void
pipe_free_kmem(cpipe)1630 pipe_free_kmem(cpipe)
1631 struct pipe *cpipe;
1632 {
1633
1634 KASSERT(!mtx_owned(PIPE_MTX(cpipe)),
1635 ("pipe_free_kmem: pipe mutex locked"));
1636
1637 if (cpipe->pipe_buffer.buffer != NULL) {
1638 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size);
1639 vm_map_remove(pipe_map,
1640 (vm_offset_t)cpipe->pipe_buffer.buffer,
1641 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size);
1642 cpipe->pipe_buffer.buffer = NULL;
1643 }
1644 #ifndef PIPE_NODIRECT
1645 {
1646 cpipe->pipe_map.cnt = 0;
1647 cpipe->pipe_map.pos = 0;
1648 cpipe->pipe_map.npages = 0;
1649 }
1650 #endif
1651 }
1652
1653 /*
1654 * shutdown the pipe
1655 */
1656 static void
pipeclose(cpipe)1657 pipeclose(cpipe)
1658 struct pipe *cpipe;
1659 {
1660 struct pipepair *pp;
1661 struct pipe *ppipe;
1662
1663 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL"));
1664
1665 PIPE_LOCK(cpipe);
1666 pipelock(cpipe, 0);
1667 pp = cpipe->pipe_pair;
1668
1669 pipeselwakeup(cpipe);
1670
1671 /*
1672 * If the other side is blocked, wake it up saying that
1673 * we want to close it down.
1674 */
1675 cpipe->pipe_state |= PIPE_EOF;
1676 while (cpipe->pipe_busy) {
1677 wakeup(cpipe);
1678 cpipe->pipe_state |= PIPE_WANT;
1679 pipeunlock(cpipe);
1680 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
1681 pipelock(cpipe, 0);
1682 }
1683
1684
1685 /*
1686 * Disconnect from peer, if any.
1687 */
1688 ppipe = cpipe->pipe_peer;
1689 if (ppipe->pipe_present == PIPE_ACTIVE) {
1690 pipeselwakeup(ppipe);
1691
1692 ppipe->pipe_state |= PIPE_EOF;
1693 wakeup(ppipe);
1694 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0);
1695 }
1696
1697 /*
1698 * Mark this endpoint as free. Release kmem resources. We
1699 * don't mark this endpoint as unused until we've finished
1700 * doing that, or the pipe might disappear out from under
1701 * us.
1702 */
1703 PIPE_UNLOCK(cpipe);
1704 pipe_free_kmem(cpipe);
1705 PIPE_LOCK(cpipe);
1706 cpipe->pipe_present = PIPE_CLOSING;
1707 pipeunlock(cpipe);
1708
1709 /*
1710 * knlist_clear() may sleep dropping the PIPE_MTX. Set the
1711 * PIPE_FINALIZED, that allows other end to free the
1712 * pipe_pair, only after the knotes are completely dismantled.
1713 */
1714 knlist_clear(&cpipe->pipe_sel.si_note, 1);
1715 cpipe->pipe_present = PIPE_FINALIZED;
1716 seldrain(&cpipe->pipe_sel);
1717 knlist_destroy(&cpipe->pipe_sel.si_note);
1718
1719 /*
1720 * If both endpoints are now closed, release the memory for the
1721 * pipe pair. If not, unlock.
1722 */
1723 if (ppipe->pipe_present == PIPE_FINALIZED) {
1724 PIPE_UNLOCK(cpipe);
1725 #ifdef MAC
1726 mac_pipe_destroy(pp);
1727 #endif
1728 uma_zfree(pipe_zone, cpipe->pipe_pair);
1729 } else
1730 PIPE_UNLOCK(cpipe);
1731 }
1732
1733 /*ARGSUSED*/
1734 static int
pipe_kqfilter(struct file * fp,struct knote * kn)1735 pipe_kqfilter(struct file *fp, struct knote *kn)
1736 {
1737 struct pipe *cpipe;
1738
1739 /*
1740 * If a filter is requested that is not supported by this file
1741 * descriptor, don't return an error, but also don't ever generate an
1742 * event.
1743 */
1744 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) {
1745 kn->kn_fop = &pipe_nfiltops;
1746 return (0);
1747 }
1748 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) {
1749 kn->kn_fop = &pipe_nfiltops;
1750 return (0);
1751 }
1752 cpipe = fp->f_data;
1753 PIPE_LOCK(cpipe);
1754 switch (kn->kn_filter) {
1755 case EVFILT_READ:
1756 kn->kn_fop = &pipe_rfiltops;
1757 break;
1758 case EVFILT_WRITE:
1759 kn->kn_fop = &pipe_wfiltops;
1760 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) {
1761 /* other end of pipe has been closed */
1762 PIPE_UNLOCK(cpipe);
1763 return (EPIPE);
1764 }
1765 cpipe = PIPE_PEER(cpipe);
1766 break;
1767 default:
1768 PIPE_UNLOCK(cpipe);
1769 return (EINVAL);
1770 }
1771
1772 kn->kn_hook = cpipe;
1773 knlist_add(&cpipe->pipe_sel.si_note, kn, 1);
1774 PIPE_UNLOCK(cpipe);
1775 return (0);
1776 }
1777
1778 static void
filt_pipedetach(struct knote * kn)1779 filt_pipedetach(struct knote *kn)
1780 {
1781 struct pipe *cpipe = kn->kn_hook;
1782
1783 PIPE_LOCK(cpipe);
1784 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1);
1785 PIPE_UNLOCK(cpipe);
1786 }
1787
1788 /*ARGSUSED*/
1789 static int
filt_piperead(struct knote * kn,long hint)1790 filt_piperead(struct knote *kn, long hint)
1791 {
1792 struct pipe *rpipe = kn->kn_hook;
1793 struct pipe *wpipe = rpipe->pipe_peer;
1794 int ret;
1795
1796 PIPE_LOCK_ASSERT(rpipe, MA_OWNED);
1797 kn->kn_data = rpipe->pipe_buffer.cnt;
1798 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
1799 kn->kn_data = rpipe->pipe_map.cnt;
1800
1801 if ((rpipe->pipe_state & PIPE_EOF) ||
1802 wpipe->pipe_present != PIPE_ACTIVE ||
1803 (wpipe->pipe_state & PIPE_EOF)) {
1804 kn->kn_flags |= EV_EOF;
1805 return (1);
1806 }
1807 ret = kn->kn_data > 0;
1808 return ret;
1809 }
1810
1811 /*ARGSUSED*/
1812 static int
filt_pipewrite(struct knote * kn,long hint)1813 filt_pipewrite(struct knote *kn, long hint)
1814 {
1815 struct pipe *wpipe;
1816
1817 /*
1818 * If this end of the pipe is closed, the knote was removed from the
1819 * knlist and the list lock (i.e., the pipe lock) is therefore not held.
1820 */
1821 wpipe = kn->kn_hook;
1822 if (wpipe->pipe_present != PIPE_ACTIVE ||
1823 (wpipe->pipe_state & PIPE_EOF)) {
1824 kn->kn_data = 0;
1825 kn->kn_flags |= EV_EOF;
1826 return (1);
1827 }
1828 PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
1829 kn->kn_data = (wpipe->pipe_buffer.size > 0) ?
1830 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF;
1831 if (wpipe->pipe_state & PIPE_DIRECTW)
1832 kn->kn_data = 0;
1833
1834 return (kn->kn_data >= PIPE_BUF);
1835 }
1836
1837 static void
filt_pipedetach_notsup(struct knote * kn)1838 filt_pipedetach_notsup(struct knote *kn)
1839 {
1840
1841 }
1842
1843 static int
filt_pipenotsup(struct knote * kn,long hint)1844 filt_pipenotsup(struct knote *kn, long hint)
1845 {
1846
1847 return (0);
1848 }
1849