sys_pipe.c revision 246907
177701Sbrian/*- 285964Sbrian * Copyright (c) 1996 John S. Dyson 377701Sbrian * Copyright (c) 2012 Giovanni Trematerra 477701Sbrian * All rights reserved. 577701Sbrian * 677701Sbrian * Redistribution and use in source and binary forms, with or without 777701Sbrian * modification, are permitted provided that the following conditions 877701Sbrian * are met: 977701Sbrian * 1. Redistributions of source code must retain the above copyright 1077701Sbrian * notice immediately at the beginning of the file, without modification, 1177701Sbrian * this list of conditions, and the following disclaimer. 1277701Sbrian * 2. Redistributions in binary form must reproduce the above copyright 1377701Sbrian * notice, this list of conditions and the following disclaimer in the 1477701Sbrian * documentation and/or other materials provided with the distribution. 1577701Sbrian * 3. Absolutely no warranty of function or purpose is made by the author 1677701Sbrian * John S. Dyson. 1777701Sbrian * 4. Modifications may be freely made to this file if the above conditions 1877701Sbrian * are met. 1977701Sbrian */ 2077701Sbrian 2177701Sbrian/* 2277701Sbrian * This file contains a high-performance replacement for the socket-based 2377701Sbrian * pipes scheme originally used in FreeBSD/4.4Lite. It does not support 2477701Sbrian * all features of sockets, but does do everything that pipes normally 2577701Sbrian * do. 2677701Sbrian */ 2784195Sdillon 2884195Sdillon/* 2984195Sdillon * This code has two modes of operation, a small write mode and a large 3026026Sbrian * write mode. The small write mode acts like conventional pipes with 3126026Sbrian * a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the 3226026Sbrian * "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT 3326026Sbrian * and PIPE_SIZE in size, the sending process pins the underlying pages in 3426026Sbrian * memory, and the receiving process copies directly from these pinned pages 3526026Sbrian * in the sending process. 3626026Sbrian * 3726026Sbrian * If the sending process receives a signal, it is possible that it will 3826026Sbrian * go away, and certainly its address space can change, because control 3926026Sbrian * is returned back to the user-mode side. In that case, the pipe code 4026026Sbrian * arranges to copy the buffer supplied by the user process, to a pageable 4126026Sbrian * kernel buffer, and the receiving process will grab the data from the 4226026Sbrian * pageable kernel buffer. Since signals don't happen all that often, 4326026Sbrian * the copy operation is normally eliminated. 44131612Sdes * 45131612Sdes * The constant PIPE_MINDIRECT is chosen to make sure that buffering will 46131612Sdes * happen for small transfers so that the system will not spend all of 47131612Sdes * its time context switching. 4826026Sbrian * 4926026Sbrian * In order to limit the resource use of pipes, two sysctls exist: 5026026Sbrian * 5126026Sbrian * kern.ipc.maxpipekva - This is a hard limit on the amount of pageable 5299207Sbrian * address space available to us in pipe_map. This value is normally 5326026Sbrian * autotuned, but may also be loader tuned. 5426026Sbrian * 5526026Sbrian * kern.ipc.pipekva - This read-only sysctl tracks the current amount of 5626026Sbrian * memory in use by pipes. 5726026Sbrian * 5826026Sbrian * Based on how large pipekva is relative to maxpipekva, the following 5926026Sbrian * will happen: 6026026Sbrian * 6126026Sbrian * 0% - 50%: 6226026Sbrian * New pipes are given 16K of memory backing, pipes may dynamically 6326026Sbrian * grow to as large as 64K where needed. 6426026Sbrian * 50% - 75%: 6526026Sbrian * New pipes are given 4K (or PAGE_SIZE) of memory backing, 6626026Sbrian * existing pipes may NOT grow. 6726026Sbrian * 75% - 100%: 68127094Sdes * New pipes are given 4K (or PAGE_SIZE) of memory backing, 69127094Sdes * existing pipes will be shrunk down to 4K whenever possible. 70127094Sdes * 71127094Sdes * Resizing may be disabled by setting kern.ipc.piperesizeallowed=0. If 72127094Sdes * that is set, the only resize that will occur is the 0 -> SMALL_PIPE_SIZE 73127094Sdes * resize which MUST occur for reverse-direction pipes when they are 7499207Sbrian * first used. 75127094Sdes * 76127094Sdes * Additional information about the current state of pipes may be obtained 77127094Sdes * from kern.ipc.pipes, kern.ipc.pipefragretry, kern.ipc.pipeallocfail, 78127094Sdes * and kern.ipc.piperesizefail. 79127094Sdes * 80127094Sdes * Locking rules: There are two locks present here: A mutex, used via 8199207Sbrian * PIPE_LOCK, and a flag, used via pipelock(). All locking is done via 8226026Sbrian * the flag, as mutexes can not persist over uiomove. The mutex 83127094Sdes * exists only to guard access to the flag, and is not in itself a 84127094Sdes * locking mechanism. Also note that there is only a single mutex for 85127094Sdes * both directions of a pipe. 86127094Sdes * 8726026Sbrian * As pipelock() may have to sleep before it can acquire the flag, it 88127094Sdes * is important to reread all data after a call to pipelock(); everything 89127094Sdes * in the structure may have changed. 90127094Sdes */ 91127094Sdes 92127094Sdes#include <sys/cdefs.h> 93127094Sdes__FBSDID("$FreeBSD: head/sys/kern/sys_pipe.c 246907 2013-02-17 11:48:16Z pjd $"); 9426026Sbrian 9526026Sbrian#include <sys/param.h> 96127094Sdes#include <sys/systm.h> 97127094Sdes#include <sys/conf.h> 98127094Sdes#include <sys/fcntl.h> 99127094Sdes#include <sys/file.h> 10026026Sbrian#include <sys/filedesc.h> 101127094Sdes#include <sys/filio.h> 102127094Sdes#include <sys/kernel.h> 103127094Sdes#include <sys/lock.h> 104127094Sdes#include <sys/mutex.h> 105127094Sdes#include <sys/ttycom.h> 106127094Sdes#include <sys/stat.h> 107127094Sdes#include <sys/malloc.h> 10826026Sbrian#include <sys/poll.h> 109127094Sdes#include <sys/selinfo.h> 110127094Sdes#include <sys/signalvar.h> 111127094Sdes#include <sys/syscallsubr.h> 112127094Sdes#include <sys/sysctl.h> 113127094Sdes#include <sys/sysproto.h> 114127094Sdes#include <sys/pipe.h> 115127094Sdes#include <sys/proc.h> 116127094Sdes#include <sys/vnode.h> 117127094Sdes#include <sys/uio.h> 11826026Sbrian#include <sys/event.h> 119127094Sdes 120127094Sdes#include <security/mac/mac_framework.h> 121127094Sdes 122127094Sdes#include <vm/vm.h> 123127094Sdes#include <vm/vm_param.h> 124127094Sdes#include <vm/vm_object.h> 125127094Sdes#include <vm/vm_kern.h> 126127094Sdes#include <vm/vm_extern.h> 127127094Sdes#include <vm/pmap.h> 128127094Sdes#include <vm/vm_map.h> 129127094Sdes#include <vm/vm_page.h> 130127094Sdes#include <vm/uma.h> 131127094Sdes 132127094Sdes/* XXX */ 133127094Sdesint do_pipe(struct thread *td, int fildes[2], int flags); 134127094Sdes 135127094Sdes/* 136127094Sdes * Use this define if you want to disable *fancy* VM things. Expect an 137127094Sdes * approx 30% decrease in transfer rate. This could be useful for 138127094Sdes * NetBSD or OpenBSD. 139127094Sdes */ 140127094Sdes/* #define PIPE_NODIRECT */ 141127094Sdes 142127094Sdes#define PIPE_PEER(pipe) \ 14326026Sbrian (((pipe)->pipe_state & PIPE_NAMED) ? (pipe) : ((pipe)->pipe_peer)) 144127094Sdes 145127094Sdes/* 146127094Sdes * interfaces to the outside world 147127094Sdes */ 148127094Sdesstatic fo_rdwr_t pipe_read; 149127094Sdesstatic fo_rdwr_t pipe_write; 150127094Sdesstatic fo_truncate_t pipe_truncate; 151127094Sdesstatic fo_ioctl_t pipe_ioctl; 152127094Sdesstatic fo_poll_t pipe_poll; 153127094Sdesstatic fo_kqfilter_t pipe_kqfilter; 154127094Sdesstatic fo_stat_t pipe_stat; 15526026Sbrianstatic fo_close_t pipe_close; 156127094Sdesstatic fo_chmod_t pipe_chmod; 157127094Sdesstatic fo_chown_t pipe_chown; 158127094Sdes 159127094Sdesstruct fileops pipeops = { 160127094Sdes .fo_read = pipe_read, 161127094Sdes .fo_write = pipe_write, 162127094Sdes .fo_truncate = pipe_truncate, 163127094Sdes .fo_ioctl = pipe_ioctl, 164127094Sdes .fo_poll = pipe_poll, 165127094Sdes .fo_kqfilter = pipe_kqfilter, 166127094Sdes .fo_stat = pipe_stat, 16726026Sbrian .fo_close = pipe_close, 168127094Sdes .fo_chmod = pipe_chmod, 169127094Sdes .fo_chown = pipe_chown, 170127094Sdes .fo_flags = DFLAG_PASSABLE 171127094Sdes}; 172127094Sdes 173127094Sdesstatic void filt_pipedetach(struct knote *kn); 174127094Sdesstatic void filt_pipedetach_notsup(struct knote *kn); 175127094Sdesstatic int filt_pipenotsup(struct knote *kn, long hint); 176127094Sdesstatic int filt_piperead(struct knote *kn, long hint); 177127094Sdesstatic int filt_pipewrite(struct knote *kn, long hint); 178127094Sdes 17926026Sbrianstatic struct filterops pipe_nfiltops = { 180127094Sdes .f_isfd = 1, 181127094Sdes .f_detach = filt_pipedetach_notsup, 182127094Sdes .f_event = filt_pipenotsup 183127094Sdes}; 184127094Sdesstatic struct filterops pipe_rfiltops = { 185127094Sdes .f_isfd = 1, 186127094Sdes .f_detach = filt_pipedetach, 187127094Sdes .f_event = filt_piperead 188127094Sdes}; 189127094Sdesstatic struct filterops pipe_wfiltops = { 190127094Sdes .f_isfd = 1, 19126026Sbrian .f_detach = filt_pipedetach, 192127094Sdes .f_event = filt_pipewrite 193127094Sdes}; 194127094Sdes 195127094Sdes/* 196127094Sdes * Default pipe buffer size(s), this can be kind-of large now because pipe 197127094Sdes * space is pageable. The pipe code will try to maintain locality of 198127094Sdes * reference for performance reasons, so small amounts of outstanding I/O 199127094Sdes * will not wipe the cache. 200127094Sdes */ 201127094Sdes#define MINPIPESIZE (PIPE_SIZE/3) 202127094Sdes#define MAXPIPESIZE (2*PIPE_SIZE/3) 20326026Sbrian 204127094Sdesstatic long amountpipekva; 205127094Sdesstatic int pipefragretry; 206127094Sdesstatic int pipeallocfail; 207127094Sdesstatic int piperesizefail; 208127094Sdesstatic int piperesizeallowed = 1; 209127094Sdes 210127094SdesSYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN, 211127094Sdes &maxpipekva, 0, "Pipe KVA limit"); 212127094SdesSYSCTL_LONG(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD, 213127094Sdes &amountpipekva, 0, "Pipe KVA usage"); 214127094SdesSYSCTL_INT(_kern_ipc, OID_AUTO, pipefragretry, CTLFLAG_RD, 215127094Sdes &pipefragretry, 0, "Pipe allocation retries due to fragmentation"); 216127094SdesSYSCTL_INT(_kern_ipc, OID_AUTO, pipeallocfail, CTLFLAG_RD, 217127094Sdes &pipeallocfail, 0, "Pipe allocation failures"); 218127094SdesSYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, CTLFLAG_RD, 219127094Sdes &piperesizefail, 0, "Pipe resize failures"); 220127094SdesSYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW, 221127094Sdes &piperesizeallowed, 0, "Pipe resizing allowed"); 222127094Sdes 223127094Sdesstatic void pipeinit(void *dummy __unused); 224127094Sdesstatic void pipeclose(struct pipe *cpipe); 225127094Sdesstatic void pipe_free_kmem(struct pipe *cpipe); 226127094Sdesstatic int pipe_create(struct pipe *pipe, int backing); 227127094Sdesstatic int pipe_paircreate(struct thread *td, struct pipepair **p_pp); 228127094Sdesstatic __inline int pipelock(struct pipe *cpipe, int catch); 229127094Sdesstatic __inline void pipeunlock(struct pipe *cpipe); 230127094Sdes#ifndef PIPE_NODIRECT 231127094Sdesstatic int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio); 232127094Sdesstatic void pipe_destroy_write_buffer(struct pipe *wpipe); 233127094Sdesstatic int pipe_direct_write(struct pipe *wpipe, struct uio *uio); 234127094Sdesstatic void pipe_clone_write_buffer(struct pipe *wpipe); 235127094Sdes#endif 236127094Sdesstatic int pipespace(struct pipe *cpipe, int size); 237127094Sdesstatic int pipespace_new(struct pipe *cpipe, int size); 238127094Sdes 239127094Sdesstatic int pipe_zone_ctor(void *mem, int size, void *arg, int flags); 240127094Sdesstatic int pipe_zone_init(void *mem, int size, int flags); 241127094Sdesstatic void pipe_zone_fini(void *mem, int size); 242127094Sdes 243127094Sdesstatic uma_zone_t pipe_zone; 244127094Sdesstatic struct unrhdr *pipeino_unr; 245127094Sdesstatic dev_t pipedev_ino; 246127094Sdes 247127094SdesSYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL); 248127094Sdes 24926026Sbrianstatic void 250127094Sdespipeinit(void *dummy __unused) 251127094Sdes{ 252127094Sdes 253127094Sdes pipe_zone = uma_zcreate("pipe", sizeof(struct pipepair), 25499207Sbrian pipe_zone_ctor, NULL, pipe_zone_init, pipe_zone_fini, 25526026Sbrian UMA_ALIGN_PTR, 0); 256127094Sdes KASSERT(pipe_zone != NULL, ("pipe_zone not initialized")); 257127094Sdes pipeino_unr = new_unrhdr(1, INT32_MAX, NULL); 258127094Sdes KASSERT(pipeino_unr != NULL, ("pipe fake inodes not initialized")); 25982050Sru pipedev_ino = devfs_alloc_cdp_inode(); 260127094Sdes KASSERT(pipedev_ino > 0, ("pipe dev inode not initialized")); 261127094Sdes} 262127094Sdes 263127094Sdesstatic int 264127094Sdespipe_zone_ctor(void *mem, int size, void *arg, int flags) 26526026Sbrian{ 266127094Sdes struct pipepair *pp; 267127094Sdes struct pipe *rpipe, *wpipe; 268127094Sdes 269127094Sdes KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size")); 270127094Sdes 271127094Sdes pp = (struct pipepair *)mem; 272127094Sdes 273127094Sdes /* 274127094Sdes * We zero both pipe endpoints to make sure all the kmem pointers 275127094Sdes * are NULL, flag fields are zero'd, etc. We timestamp both 276127094Sdes * endpoints with the same time. 277127094Sdes */ 278127094Sdes rpipe = &pp->pp_rpipe; 279127094Sdes bzero(rpipe, sizeof(*rpipe)); 280127094Sdes vfs_timestamp(&rpipe->pipe_ctime); 28136711Sbrian rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime; 282127094Sdes 283127094Sdes wpipe = &pp->pp_wpipe; 28436711Sbrian bzero(wpipe, sizeof(*wpipe)); 28532377Seivind wpipe->pipe_ctime = rpipe->pipe_ctime; 286127094Sdes wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime; 287127094Sdes 288127094Sdes rpipe->pipe_peer = wpipe; 289127094Sdes rpipe->pipe_pair = pp; 290127094Sdes wpipe->pipe_peer = rpipe; 291127094Sdes wpipe->pipe_pair = pp; 292127094Sdes 293127094Sdes /* 294127094Sdes * Mark both endpoints as present; they will later get free'd 295127094Sdes * one at a time. When both are free'd, then the whole pair 296127094Sdes * is released. 297127094Sdes */ 298127094Sdes rpipe->pipe_present = PIPE_ACTIVE; 299127094Sdes wpipe->pipe_present = PIPE_ACTIVE; 300127094Sdes 301127094Sdes /* 302127094Sdes * Eventually, the MAC Framework may initialize the label 303127094Sdes * in ctor or init, but for now we do it elswhere to avoid 304127094Sdes * blocking in ctor or init. 305127094Sdes */ 306127094Sdes pp->pp_label = NULL; 307127094Sdes 308127094Sdes return (0); 309127094Sdes} 310127094Sdes 311127094Sdesstatic int 312127094Sdespipe_zone_init(void *mem, int size, int flags) 313127094Sdes{ 314127094Sdes struct pipepair *pp; 315127094Sdes 316127094Sdes KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size")); 317127094Sdes 318127094Sdes pp = (struct pipepair *)mem; 319127094Sdes 320127094Sdes mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_RECURSE); 321127094Sdes return (0); 322127094Sdes} 323127094Sdes 324127094Sdesstatic void 325127094Sdespipe_zone_fini(void *mem, int size) 326127094Sdes{ 327127094Sdes struct pipepair *pp; 328127094Sdes 329127094Sdes KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size")); 330127094Sdes 331127094Sdes pp = (struct pipepair *)mem; 332127094Sdes 333127094Sdes mtx_destroy(&pp->pp_mtx); 334127094Sdes} 335127094Sdes 336127094Sdesstatic int 337127094Sdespipe_paircreate(struct thread *td, struct pipepair **p_pp) 338127094Sdes{ 339127094Sdes struct pipepair *pp; 34026026Sbrian struct pipe *rpipe, *wpipe; 34126026Sbrian int error; 342127094Sdes 343127094Sdes *p_pp = pp = uma_zalloc(pipe_zone, M_WAITOK); 34426026Sbrian#ifdef MAC 345127094Sdes /* 346127094Sdes * The MAC label is shared between the connected endpoints. As a 347127094Sdes * result mac_pipe_init() and mac_pipe_create() are called once 348127094Sdes * for the pair, and not on the endpoints. 34926026Sbrian */ 350127094Sdes mac_pipe_init(pp); 351127094Sdes mac_pipe_create(td->td_ucred, pp); 352127094Sdes#endif 35399207Sbrian rpipe = &pp->pp_rpipe; 354127094Sdes wpipe = &pp->pp_wpipe; 355127094Sdes 356127094Sdes knlist_init_mtx(&rpipe->pipe_sel.si_note, PIPE_MTX(rpipe)); 357127094Sdes knlist_init_mtx(&wpipe->pipe_sel.si_note, PIPE_MTX(wpipe)); 358127094Sdes 359127094Sdes /* Only the forward direction pipe is backed by default */ 360127094Sdes if ((error = pipe_create(rpipe, 1)) != 0 || 36126026Sbrian (error = pipe_create(wpipe, 0)) != 0) { 362127094Sdes pipeclose(rpipe); 363127094Sdes pipeclose(wpipe); 364127094Sdes return (error); 365127094Sdes } 366127094Sdes 36726026Sbrian rpipe->pipe_state |= PIPE_DIRECTOK; 36826026Sbrian wpipe->pipe_state |= PIPE_DIRECTOK; 36926026Sbrian return (0); 37026026Sbrian} 37126026Sbrian 37226026Sbrianint 37326026Sbrianpipe_named_ctor(struct pipe **ppipe, struct thread *td) 37426026Sbrian{ 37526026Sbrian struct pipepair *pp; 37626026Sbrian int error; 37726026Sbrian 37826026Sbrian error = pipe_paircreate(td, &pp); 37926026Sbrian if (error != 0) 38026026Sbrian return (error); 38126026Sbrian pp->pp_rpipe.pipe_state |= PIPE_NAMED; 38226026Sbrian *ppipe = &pp->pp_rpipe; 38326026Sbrian return (0); 38426026Sbrian} 38526026Sbrian 38626026Sbrianvoid 387pipe_dtor(struct pipe *dpipe) 388{ 389 ino_t ino; 390 391 ino = dpipe->pipe_ino; 392 funsetown(&dpipe->pipe_sigio); 393 pipeclose(dpipe); 394 if (dpipe->pipe_state & PIPE_NAMED) { 395 dpipe = dpipe->pipe_peer; 396 funsetown(&dpipe->pipe_sigio); 397 pipeclose(dpipe); 398 } 399 if (ino != 0 && ino != (ino_t)-1) 400 free_unr(pipeino_unr, ino); 401} 402 403/* 404 * The pipe system call for the DTYPE_PIPE type of pipes. If we fail, let 405 * the zone pick up the pieces via pipeclose(). 406 */ 407int 408kern_pipe(struct thread *td, int fildes[2]) 409{ 410 411 return (do_pipe(td, fildes, 0)); 412} 413 414int 415do_pipe(struct thread *td, int fildes[2], int flags) 416{ 417 struct filedesc *fdp; 418 struct file *rf, *wf; 419 struct pipe *rpipe, *wpipe; 420 struct pipepair *pp; 421 int fd, fflags, error; 422 423 fdp = td->td_proc->p_fd; 424 error = pipe_paircreate(td, &pp); 425 if (error != 0) 426 return (error); 427 rpipe = &pp->pp_rpipe; 428 wpipe = &pp->pp_wpipe; 429 error = falloc(td, &rf, &fd, flags); 430 if (error) { 431 pipeclose(rpipe); 432 pipeclose(wpipe); 433 return (error); 434 } 435 /* An extra reference on `rf' has been held for us by falloc(). */ 436 fildes[0] = fd; 437 438 fflags = FREAD | FWRITE; 439 if ((flags & O_NONBLOCK) != 0) 440 fflags |= FNONBLOCK; 441 442 /* 443 * Warning: once we've gotten past allocation of the fd for the 444 * read-side, we can only drop the read side via fdrop() in order 445 * to avoid races against processes which manage to dup() the read 446 * side while we are blocked trying to allocate the write side. 447 */ 448 finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops); 449 error = falloc(td, &wf, &fd, flags); 450 if (error) { 451 fdclose(fdp, rf, fildes[0], td); 452 fdrop(rf, td); 453 /* rpipe has been closed by fdrop(). */ 454 pipeclose(wpipe); 455 return (error); 456 } 457 /* An extra reference on `wf' has been held for us by falloc(). */ 458 finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops); 459 fdrop(wf, td); 460 fildes[1] = fd; 461 fdrop(rf, td); 462 463 return (0); 464} 465 466/* ARGSUSED */ 467int 468sys_pipe(struct thread *td, struct pipe_args *uap) 469{ 470 int error; 471 int fildes[2]; 472 473 error = kern_pipe(td, fildes); 474 if (error) 475 return (error); 476 477 td->td_retval[0] = fildes[0]; 478 td->td_retval[1] = fildes[1]; 479 480 return (0); 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 */ 489static int 490pipespace_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")); 502retry: 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, 1, 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 */ 557static int 558pipespace(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 */ 571static __inline int 572pipelock(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 */ 594static __inline void 595pipeunlock(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 609void 610pipeselwakeup(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 */ 629static int 630pipe_create(pipe, backing) 631 struct pipe *pipe; 632 int backing; 633{ 634 int error; 635 636 if (backing) { 637 if (amountpipekva > maxpipekva / 2) 638 error = pipespace_new(pipe, SMALL_PIPE_SIZE); 639 else 640 error = pipespace_new(pipe, PIPE_SIZE); 641 } else { 642 /* If we're not backing this pipe, no need to do anything. */ 643 error = 0; 644 } 645 pipe->pipe_ino = -1; 646 return (error); 647} 648 649/* ARGSUSED */ 650static int 651pipe_read(fp, uio, active_cred, flags, td) 652 struct file *fp; 653 struct uio *uio; 654 struct ucred *active_cred; 655 struct thread *td; 656 int flags; 657{ 658 struct pipe *rpipe; 659 int error; 660 int nread = 0; 661 int size; 662 663 rpipe = fp->f_data; 664 PIPE_LOCK(rpipe); 665 ++rpipe->pipe_busy; 666 error = pipelock(rpipe, 1); 667 if (error) 668 goto unlocked_error; 669 670#ifdef MAC 671 error = mac_pipe_check_read(active_cred, rpipe->pipe_pair); 672 if (error) 673 goto locked_error; 674#endif 675 if (amountpipekva > (3 * maxpipekva) / 4) { 676 if (!(rpipe->pipe_state & PIPE_DIRECTW) && 677 (rpipe->pipe_buffer.size > SMALL_PIPE_SIZE) && 678 (rpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) && 679 (piperesizeallowed == 1)) { 680 PIPE_UNLOCK(rpipe); 681 pipespace(rpipe, SMALL_PIPE_SIZE); 682 PIPE_LOCK(rpipe); 683 } 684 } 685 686 while (uio->uio_resid) { 687 /* 688 * normal pipe buffer receive 689 */ 690 if (rpipe->pipe_buffer.cnt > 0) { 691 size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out; 692 if (size > rpipe->pipe_buffer.cnt) 693 size = rpipe->pipe_buffer.cnt; 694 if (size > uio->uio_resid) 695 size = uio->uio_resid; 696 697 PIPE_UNLOCK(rpipe); 698 error = uiomove( 699 &rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out], 700 size, uio); 701 PIPE_LOCK(rpipe); 702 if (error) 703 break; 704 705 rpipe->pipe_buffer.out += size; 706 if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size) 707 rpipe->pipe_buffer.out = 0; 708 709 rpipe->pipe_buffer.cnt -= size; 710 711 /* 712 * If there is no more to read in the pipe, reset 713 * its pointers to the beginning. This improves 714 * cache hit stats. 715 */ 716 if (rpipe->pipe_buffer.cnt == 0) { 717 rpipe->pipe_buffer.in = 0; 718 rpipe->pipe_buffer.out = 0; 719 } 720 nread += size; 721#ifndef PIPE_NODIRECT 722 /* 723 * Direct copy, bypassing a kernel buffer. 724 */ 725 } else if ((size = rpipe->pipe_map.cnt) && 726 (rpipe->pipe_state & PIPE_DIRECTW)) { 727 if (size > uio->uio_resid) 728 size = (u_int) uio->uio_resid; 729 730 PIPE_UNLOCK(rpipe); 731 error = uiomove_fromphys(rpipe->pipe_map.ms, 732 rpipe->pipe_map.pos, size, uio); 733 PIPE_LOCK(rpipe); 734 if (error) 735 break; 736 nread += size; 737 rpipe->pipe_map.pos += size; 738 rpipe->pipe_map.cnt -= size; 739 if (rpipe->pipe_map.cnt == 0) { 740 rpipe->pipe_state &= ~(PIPE_DIRECTW|PIPE_WANTW); 741 wakeup(rpipe); 742 } 743#endif 744 } else { 745 /* 746 * detect EOF condition 747 * read returns 0 on EOF, no need to set error 748 */ 749 if (rpipe->pipe_state & PIPE_EOF) 750 break; 751 752 /* 753 * If the "write-side" has been blocked, wake it up now. 754 */ 755 if (rpipe->pipe_state & PIPE_WANTW) { 756 rpipe->pipe_state &= ~PIPE_WANTW; 757 wakeup(rpipe); 758 } 759 760 /* 761 * Break if some data was read. 762 */ 763 if (nread > 0) 764 break; 765 766 /* 767 * Unlock the pipe buffer for our remaining processing. 768 * We will either break out with an error or we will 769 * sleep and relock to loop. 770 */ 771 pipeunlock(rpipe); 772 773 /* 774 * Handle non-blocking mode operation or 775 * wait for more data. 776 */ 777 if (fp->f_flag & FNONBLOCK) { 778 error = EAGAIN; 779 } else { 780 rpipe->pipe_state |= PIPE_WANTR; 781 if ((error = msleep(rpipe, PIPE_MTX(rpipe), 782 PRIBIO | PCATCH, 783 "piperd", 0)) == 0) 784 error = pipelock(rpipe, 1); 785 } 786 if (error) 787 goto unlocked_error; 788 } 789 } 790#ifdef MAC 791locked_error: 792#endif 793 pipeunlock(rpipe); 794 795 /* XXX: should probably do this before getting any locks. */ 796 if (error == 0) 797 vfs_timestamp(&rpipe->pipe_atime); 798unlocked_error: 799 --rpipe->pipe_busy; 800 801 /* 802 * PIPE_WANT processing only makes sense if pipe_busy is 0. 803 */ 804 if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) { 805 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW); 806 wakeup(rpipe); 807 } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) { 808 /* 809 * Handle write blocking hysteresis. 810 */ 811 if (rpipe->pipe_state & PIPE_WANTW) { 812 rpipe->pipe_state &= ~PIPE_WANTW; 813 wakeup(rpipe); 814 } 815 } 816 817 if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF) 818 pipeselwakeup(rpipe); 819 820 PIPE_UNLOCK(rpipe); 821 return (error); 822} 823 824#ifndef PIPE_NODIRECT 825/* 826 * Map the sending processes' buffer into kernel space and wire it. 827 * This is similar to a physical write operation. 828 */ 829static int 830pipe_build_write_buffer(wpipe, uio) 831 struct pipe *wpipe; 832 struct uio *uio; 833{ 834 u_int size; 835 int i; 836 837 PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED); 838 KASSERT(wpipe->pipe_state & PIPE_DIRECTW, 839 ("Clone attempt on non-direct write pipe!")); 840 841 if (uio->uio_iov->iov_len > wpipe->pipe_buffer.size) 842 size = wpipe->pipe_buffer.size; 843 else 844 size = uio->uio_iov->iov_len; 845 846 if ((i = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 847 (vm_offset_t)uio->uio_iov->iov_base, size, VM_PROT_READ, 848 wpipe->pipe_map.ms, PIPENPAGES)) < 0) 849 return (EFAULT); 850 851/* 852 * set up the control block 853 */ 854 wpipe->pipe_map.npages = i; 855 wpipe->pipe_map.pos = 856 ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK; 857 wpipe->pipe_map.cnt = size; 858 859/* 860 * and update the uio data 861 */ 862 863 uio->uio_iov->iov_len -= size; 864 uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size; 865 if (uio->uio_iov->iov_len == 0) 866 uio->uio_iov++; 867 uio->uio_resid -= size; 868 uio->uio_offset += size; 869 return (0); 870} 871 872/* 873 * unmap and unwire the process buffer 874 */ 875static void 876pipe_destroy_write_buffer(wpipe) 877 struct pipe *wpipe; 878{ 879 880 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 881 vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages); 882 wpipe->pipe_map.npages = 0; 883} 884 885/* 886 * In the case of a signal, the writing process might go away. This 887 * code copies the data into the circular buffer so that the source 888 * pages can be freed without loss of data. 889 */ 890static void 891pipe_clone_write_buffer(wpipe) 892 struct pipe *wpipe; 893{ 894 struct uio uio; 895 struct iovec iov; 896 int size; 897 int pos; 898 899 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 900 size = wpipe->pipe_map.cnt; 901 pos = wpipe->pipe_map.pos; 902 903 wpipe->pipe_buffer.in = size; 904 wpipe->pipe_buffer.out = 0; 905 wpipe->pipe_buffer.cnt = size; 906 wpipe->pipe_state &= ~PIPE_DIRECTW; 907 908 PIPE_UNLOCK(wpipe); 909 iov.iov_base = wpipe->pipe_buffer.buffer; 910 iov.iov_len = size; 911 uio.uio_iov = &iov; 912 uio.uio_iovcnt = 1; 913 uio.uio_offset = 0; 914 uio.uio_resid = size; 915 uio.uio_segflg = UIO_SYSSPACE; 916 uio.uio_rw = UIO_READ; 917 uio.uio_td = curthread; 918 uiomove_fromphys(wpipe->pipe_map.ms, pos, size, &uio); 919 PIPE_LOCK(wpipe); 920 pipe_destroy_write_buffer(wpipe); 921} 922 923/* 924 * This implements the pipe buffer write mechanism. Note that only 925 * a direct write OR a normal pipe write can be pending at any given time. 926 * If there are any characters in the pipe buffer, the direct write will 927 * be deferred until the receiving process grabs all of the bytes from 928 * the pipe buffer. Then the direct mapping write is set-up. 929 */ 930static int 931pipe_direct_write(wpipe, uio) 932 struct pipe *wpipe; 933 struct uio *uio; 934{ 935 int error; 936 937retry: 938 PIPE_LOCK_ASSERT(wpipe, MA_OWNED); 939 error = pipelock(wpipe, 1); 940 if (wpipe->pipe_state & PIPE_EOF) 941 error = EPIPE; 942 if (error) { 943 pipeunlock(wpipe); 944 goto error1; 945 } 946 while (wpipe->pipe_state & PIPE_DIRECTW) { 947 if (wpipe->pipe_state & PIPE_WANTR) { 948 wpipe->pipe_state &= ~PIPE_WANTR; 949 wakeup(wpipe); 950 } 951 pipeselwakeup(wpipe); 952 wpipe->pipe_state |= PIPE_WANTW; 953 pipeunlock(wpipe); 954 error = msleep(wpipe, PIPE_MTX(wpipe), 955 PRIBIO | PCATCH, "pipdww", 0); 956 if (error) 957 goto error1; 958 else 959 goto retry; 960 } 961 wpipe->pipe_map.cnt = 0; /* transfer not ready yet */ 962 if (wpipe->pipe_buffer.cnt > 0) { 963 if (wpipe->pipe_state & PIPE_WANTR) { 964 wpipe->pipe_state &= ~PIPE_WANTR; 965 wakeup(wpipe); 966 } 967 pipeselwakeup(wpipe); 968 wpipe->pipe_state |= PIPE_WANTW; 969 pipeunlock(wpipe); 970 error = msleep(wpipe, PIPE_MTX(wpipe), 971 PRIBIO | PCATCH, "pipdwc", 0); 972 if (error) 973 goto error1; 974 else 975 goto retry; 976 } 977 978 wpipe->pipe_state |= PIPE_DIRECTW; 979 980 PIPE_UNLOCK(wpipe); 981 error = pipe_build_write_buffer(wpipe, uio); 982 PIPE_LOCK(wpipe); 983 if (error) { 984 wpipe->pipe_state &= ~PIPE_DIRECTW; 985 pipeunlock(wpipe); 986 goto error1; 987 } 988 989 error = 0; 990 while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) { 991 if (wpipe->pipe_state & PIPE_EOF) { 992 pipe_destroy_write_buffer(wpipe); 993 pipeselwakeup(wpipe); 994 pipeunlock(wpipe); 995 error = EPIPE; 996 goto error1; 997 } 998 if (wpipe->pipe_state & PIPE_WANTR) { 999 wpipe->pipe_state &= ~PIPE_WANTR; 1000 wakeup(wpipe); 1001 } 1002 pipeselwakeup(wpipe); 1003 wpipe->pipe_state |= PIPE_WANTW; 1004 pipeunlock(wpipe); 1005 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH, 1006 "pipdwt", 0); 1007 pipelock(wpipe, 0); 1008 } 1009 1010 if (wpipe->pipe_state & PIPE_EOF) 1011 error = EPIPE; 1012 if (wpipe->pipe_state & PIPE_DIRECTW) { 1013 /* 1014 * this bit of trickery substitutes a kernel buffer for 1015 * the process that might be going away. 1016 */ 1017 pipe_clone_write_buffer(wpipe); 1018 } else { 1019 pipe_destroy_write_buffer(wpipe); 1020 } 1021 pipeunlock(wpipe); 1022 return (error); 1023 1024error1: 1025 wakeup(wpipe); 1026 return (error); 1027} 1028#endif 1029 1030static int 1031pipe_write(fp, uio, active_cred, flags, td) 1032 struct file *fp; 1033 struct uio *uio; 1034 struct ucred *active_cred; 1035 struct thread *td; 1036 int flags; 1037{ 1038 int error = 0; 1039 int desiredsize; 1040 ssize_t orig_resid; 1041 struct pipe *wpipe, *rpipe; 1042 1043 rpipe = fp->f_data; 1044 wpipe = PIPE_PEER(rpipe); 1045 PIPE_LOCK(rpipe); 1046 error = pipelock(wpipe, 1); 1047 if (error) { 1048 PIPE_UNLOCK(rpipe); 1049 return (error); 1050 } 1051 /* 1052 * detect loss of pipe read side, issue SIGPIPE if lost. 1053 */ 1054 if (wpipe->pipe_present != PIPE_ACTIVE || 1055 (wpipe->pipe_state & PIPE_EOF)) { 1056 pipeunlock(wpipe); 1057 PIPE_UNLOCK(rpipe); 1058 return (EPIPE); 1059 } 1060#ifdef MAC 1061 error = mac_pipe_check_write(active_cred, wpipe->pipe_pair); 1062 if (error) { 1063 pipeunlock(wpipe); 1064 PIPE_UNLOCK(rpipe); 1065 return (error); 1066 } 1067#endif 1068 ++wpipe->pipe_busy; 1069 1070 /* Choose a larger size if it's advantageous */ 1071 desiredsize = max(SMALL_PIPE_SIZE, wpipe->pipe_buffer.size); 1072 while (desiredsize < wpipe->pipe_buffer.cnt + uio->uio_resid) { 1073 if (piperesizeallowed != 1) 1074 break; 1075 if (amountpipekva > maxpipekva / 2) 1076 break; 1077 if (desiredsize == BIG_PIPE_SIZE) 1078 break; 1079 desiredsize = desiredsize * 2; 1080 } 1081 1082 /* Choose a smaller size if we're in a OOM situation */ 1083 if ((amountpipekva > (3 * maxpipekva) / 4) && 1084 (wpipe->pipe_buffer.size > SMALL_PIPE_SIZE) && 1085 (wpipe->pipe_buffer.cnt <= SMALL_PIPE_SIZE) && 1086 (piperesizeallowed == 1)) 1087 desiredsize = SMALL_PIPE_SIZE; 1088 1089 /* Resize if the above determined that a new size was necessary */ 1090 if ((desiredsize != wpipe->pipe_buffer.size) && 1091 ((wpipe->pipe_state & PIPE_DIRECTW) == 0)) { 1092 PIPE_UNLOCK(wpipe); 1093 pipespace(wpipe, desiredsize); 1094 PIPE_LOCK(wpipe); 1095 } 1096 if (wpipe->pipe_buffer.size == 0) { 1097 /* 1098 * This can only happen for reverse direction use of pipes 1099 * in a complete OOM situation. 1100 */ 1101 error = ENOMEM; 1102 --wpipe->pipe_busy; 1103 pipeunlock(wpipe); 1104 PIPE_UNLOCK(wpipe); 1105 return (error); 1106 } 1107 1108 pipeunlock(wpipe); 1109 1110 orig_resid = uio->uio_resid; 1111 1112 while (uio->uio_resid) { 1113 int space; 1114 1115 pipelock(wpipe, 0); 1116 if (wpipe->pipe_state & PIPE_EOF) { 1117 pipeunlock(wpipe); 1118 error = EPIPE; 1119 break; 1120 } 1121#ifndef PIPE_NODIRECT 1122 /* 1123 * If the transfer is large, we can gain performance if 1124 * we do process-to-process copies directly. 1125 * If the write is non-blocking, we don't use the 1126 * direct write mechanism. 1127 * 1128 * The direct write mechanism will detect the reader going 1129 * away on us. 1130 */ 1131 if (uio->uio_segflg == UIO_USERSPACE && 1132 uio->uio_iov->iov_len >= PIPE_MINDIRECT && 1133 wpipe->pipe_buffer.size >= PIPE_MINDIRECT && 1134 (fp->f_flag & FNONBLOCK) == 0) { 1135 pipeunlock(wpipe); 1136 error = pipe_direct_write(wpipe, uio); 1137 if (error) 1138 break; 1139 continue; 1140 } 1141#endif 1142 1143 /* 1144 * Pipe buffered writes cannot be coincidental with 1145 * direct writes. We wait until the currently executing 1146 * direct write is completed before we start filling the 1147 * pipe buffer. We break out if a signal occurs or the 1148 * reader goes away. 1149 */ 1150 if (wpipe->pipe_state & PIPE_DIRECTW) { 1151 if (wpipe->pipe_state & PIPE_WANTR) { 1152 wpipe->pipe_state &= ~PIPE_WANTR; 1153 wakeup(wpipe); 1154 } 1155 pipeselwakeup(wpipe); 1156 wpipe->pipe_state |= PIPE_WANTW; 1157 pipeunlock(wpipe); 1158 error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH, 1159 "pipbww", 0); 1160 if (error) 1161 break; 1162 else 1163 continue; 1164 } 1165 1166 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; 1167 1168 /* Writes of size <= PIPE_BUF must be atomic. */ 1169 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF)) 1170 space = 0; 1171 1172 if (space > 0) { 1173 int size; /* Transfer size */ 1174 int segsize; /* first segment to transfer */ 1175 1176 /* 1177 * Transfer size is minimum of uio transfer 1178 * and free space in pipe buffer. 1179 */ 1180 if (space > uio->uio_resid) 1181 size = uio->uio_resid; 1182 else 1183 size = space; 1184 /* 1185 * First segment to transfer is minimum of 1186 * transfer size and contiguous space in 1187 * pipe buffer. If first segment to transfer 1188 * is less than the transfer size, we've got 1189 * a wraparound in the buffer. 1190 */ 1191 segsize = wpipe->pipe_buffer.size - 1192 wpipe->pipe_buffer.in; 1193 if (segsize > size) 1194 segsize = size; 1195 1196 /* Transfer first segment */ 1197 1198 PIPE_UNLOCK(rpipe); 1199 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 1200 segsize, uio); 1201 PIPE_LOCK(rpipe); 1202 1203 if (error == 0 && segsize < size) { 1204 KASSERT(wpipe->pipe_buffer.in + segsize == 1205 wpipe->pipe_buffer.size, 1206 ("Pipe buffer wraparound disappeared")); 1207 /* 1208 * Transfer remaining part now, to 1209 * support atomic writes. Wraparound 1210 * happened. 1211 */ 1212 1213 PIPE_UNLOCK(rpipe); 1214 error = uiomove( 1215 &wpipe->pipe_buffer.buffer[0], 1216 size - segsize, uio); 1217 PIPE_LOCK(rpipe); 1218 } 1219 if (error == 0) { 1220 wpipe->pipe_buffer.in += size; 1221 if (wpipe->pipe_buffer.in >= 1222 wpipe->pipe_buffer.size) { 1223 KASSERT(wpipe->pipe_buffer.in == 1224 size - segsize + 1225 wpipe->pipe_buffer.size, 1226 ("Expected wraparound bad")); 1227 wpipe->pipe_buffer.in = size - segsize; 1228 } 1229 1230 wpipe->pipe_buffer.cnt += size; 1231 KASSERT(wpipe->pipe_buffer.cnt <= 1232 wpipe->pipe_buffer.size, 1233 ("Pipe buffer overflow")); 1234 } 1235 pipeunlock(wpipe); 1236 if (error != 0) 1237 break; 1238 } else { 1239 /* 1240 * If the "read-side" has been blocked, wake it up now. 1241 */ 1242 if (wpipe->pipe_state & PIPE_WANTR) { 1243 wpipe->pipe_state &= ~PIPE_WANTR; 1244 wakeup(wpipe); 1245 } 1246 1247 /* 1248 * don't block on non-blocking I/O 1249 */ 1250 if (fp->f_flag & FNONBLOCK) { 1251 error = EAGAIN; 1252 pipeunlock(wpipe); 1253 break; 1254 } 1255 1256 /* 1257 * We have no more space and have something to offer, 1258 * wake up select/poll. 1259 */ 1260 pipeselwakeup(wpipe); 1261 1262 wpipe->pipe_state |= PIPE_WANTW; 1263 pipeunlock(wpipe); 1264 error = msleep(wpipe, PIPE_MTX(rpipe), 1265 PRIBIO | PCATCH, "pipewr", 0); 1266 if (error != 0) 1267 break; 1268 } 1269 } 1270 1271 pipelock(wpipe, 0); 1272 --wpipe->pipe_busy; 1273 1274 if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) { 1275 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR); 1276 wakeup(wpipe); 1277 } else if (wpipe->pipe_buffer.cnt > 0) { 1278 /* 1279 * If we have put any characters in the buffer, we wake up 1280 * the reader. 1281 */ 1282 if (wpipe->pipe_state & PIPE_WANTR) { 1283 wpipe->pipe_state &= ~PIPE_WANTR; 1284 wakeup(wpipe); 1285 } 1286 } 1287 1288 /* 1289 * Don't return EPIPE if I/O was successful 1290 */ 1291 if ((wpipe->pipe_buffer.cnt == 0) && 1292 (uio->uio_resid == 0) && 1293 (error == EPIPE)) { 1294 error = 0; 1295 } 1296 1297 if (error == 0) 1298 vfs_timestamp(&wpipe->pipe_mtime); 1299 1300 /* 1301 * We have something to offer, 1302 * wake up select/poll. 1303 */ 1304 if (wpipe->pipe_buffer.cnt) 1305 pipeselwakeup(wpipe); 1306 1307 pipeunlock(wpipe); 1308 PIPE_UNLOCK(rpipe); 1309 return (error); 1310} 1311 1312/* ARGSUSED */ 1313static int 1314pipe_truncate(fp, length, active_cred, td) 1315 struct file *fp; 1316 off_t length; 1317 struct ucred *active_cred; 1318 struct thread *td; 1319{ 1320 1321 /* For named pipes call the vnode operation. */ 1322 if (fp->f_vnode != NULL) 1323 return (vnops.fo_truncate(fp, length, active_cred, td)); 1324 return (EINVAL); 1325} 1326 1327/* 1328 * we implement a very minimal set of ioctls for compatibility with sockets. 1329 */ 1330static int 1331pipe_ioctl(fp, cmd, data, active_cred, td) 1332 struct file *fp; 1333 u_long cmd; 1334 void *data; 1335 struct ucred *active_cred; 1336 struct thread *td; 1337{ 1338 struct pipe *mpipe = fp->f_data; 1339 int error; 1340 1341 PIPE_LOCK(mpipe); 1342 1343#ifdef MAC 1344 error = mac_pipe_check_ioctl(active_cred, mpipe->pipe_pair, cmd, data); 1345 if (error) { 1346 PIPE_UNLOCK(mpipe); 1347 return (error); 1348 } 1349#endif 1350 1351 error = 0; 1352 switch (cmd) { 1353 1354 case FIONBIO: 1355 break; 1356 1357 case FIOASYNC: 1358 if (*(int *)data) { 1359 mpipe->pipe_state |= PIPE_ASYNC; 1360 } else { 1361 mpipe->pipe_state &= ~PIPE_ASYNC; 1362 } 1363 break; 1364 1365 case FIONREAD: 1366 if (!(fp->f_flag & FREAD)) { 1367 *(int *)data = 0; 1368 PIPE_UNLOCK(mpipe); 1369 return (0); 1370 } 1371 if (mpipe->pipe_state & PIPE_DIRECTW) 1372 *(int *)data = mpipe->pipe_map.cnt; 1373 else 1374 *(int *)data = mpipe->pipe_buffer.cnt; 1375 break; 1376 1377 case FIOSETOWN: 1378 PIPE_UNLOCK(mpipe); 1379 error = fsetown(*(int *)data, &mpipe->pipe_sigio); 1380 goto out_unlocked; 1381 1382 case FIOGETOWN: 1383 *(int *)data = fgetown(&mpipe->pipe_sigio); 1384 break; 1385 1386 /* This is deprecated, FIOSETOWN should be used instead. */ 1387 case TIOCSPGRP: 1388 PIPE_UNLOCK(mpipe); 1389 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio); 1390 goto out_unlocked; 1391 1392 /* This is deprecated, FIOGETOWN should be used instead. */ 1393 case TIOCGPGRP: 1394 *(int *)data = -fgetown(&mpipe->pipe_sigio); 1395 break; 1396 1397 default: 1398 error = ENOTTY; 1399 break; 1400 } 1401 PIPE_UNLOCK(mpipe); 1402out_unlocked: 1403 return (error); 1404} 1405 1406static int 1407pipe_poll(fp, events, active_cred, td) 1408 struct file *fp; 1409 int events; 1410 struct ucred *active_cred; 1411 struct thread *td; 1412{ 1413 struct pipe *rpipe; 1414 struct pipe *wpipe; 1415 int levents, revents; 1416#ifdef MAC 1417 int error; 1418#endif 1419 1420 revents = 0; 1421 rpipe = fp->f_data; 1422 wpipe = PIPE_PEER(rpipe); 1423 PIPE_LOCK(rpipe); 1424#ifdef MAC 1425 error = mac_pipe_check_poll(active_cred, rpipe->pipe_pair); 1426 if (error) 1427 goto locked_error; 1428#endif 1429 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) 1430 if ((rpipe->pipe_state & PIPE_DIRECTW) || 1431 (rpipe->pipe_buffer.cnt > 0)) 1432 revents |= events & (POLLIN | POLLRDNORM); 1433 1434 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) 1435 if (wpipe->pipe_present != PIPE_ACTIVE || 1436 (wpipe->pipe_state & PIPE_EOF) || 1437 (((wpipe->pipe_state & PIPE_DIRECTW) == 0) && 1438 ((wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF || 1439 wpipe->pipe_buffer.size == 0))) 1440 revents |= events & (POLLOUT | POLLWRNORM); 1441 1442 levents = events & 1443 (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND); 1444 if (rpipe->pipe_state & PIPE_NAMED && fp->f_flag & FREAD && levents && 1445 fp->f_seqcount == rpipe->pipe_wgen) 1446 events |= POLLINIGNEOF; 1447 1448 if ((events & POLLINIGNEOF) == 0) { 1449 if (rpipe->pipe_state & PIPE_EOF) { 1450 revents |= (events & (POLLIN | POLLRDNORM)); 1451 if (wpipe->pipe_present != PIPE_ACTIVE || 1452 (wpipe->pipe_state & PIPE_EOF)) 1453 revents |= POLLHUP; 1454 } 1455 } 1456 1457 if (revents == 0) { 1458 if (fp->f_flag & FREAD && events & (POLLIN | POLLRDNORM)) { 1459 selrecord(td, &rpipe->pipe_sel); 1460 if (SEL_WAITING(&rpipe->pipe_sel)) 1461 rpipe->pipe_state |= PIPE_SEL; 1462 } 1463 1464 if (fp->f_flag & FWRITE && events & (POLLOUT | POLLWRNORM)) { 1465 selrecord(td, &wpipe->pipe_sel); 1466 if (SEL_WAITING(&wpipe->pipe_sel)) 1467 wpipe->pipe_state |= PIPE_SEL; 1468 } 1469 } 1470#ifdef MAC 1471locked_error: 1472#endif 1473 PIPE_UNLOCK(rpipe); 1474 1475 return (revents); 1476} 1477 1478/* 1479 * We shouldn't need locks here as we're doing a read and this should 1480 * be a natural race. 1481 */ 1482static int 1483pipe_stat(fp, ub, active_cred, td) 1484 struct file *fp; 1485 struct stat *ub; 1486 struct ucred *active_cred; 1487 struct thread *td; 1488{ 1489 struct pipe *pipe; 1490 int new_unr; 1491#ifdef MAC 1492 int error; 1493#endif 1494 1495 pipe = fp->f_data; 1496 PIPE_LOCK(pipe); 1497#ifdef MAC 1498 error = mac_pipe_check_stat(active_cred, pipe->pipe_pair); 1499 if (error) { 1500 PIPE_UNLOCK(pipe); 1501 return (error); 1502 } 1503#endif 1504 1505 /* For named pipes ask the underlying filesystem. */ 1506 if (pipe->pipe_state & PIPE_NAMED) { 1507 PIPE_UNLOCK(pipe); 1508 return (vnops.fo_stat(fp, ub, active_cred, td)); 1509 } 1510 1511 /* 1512 * Lazily allocate an inode number for the pipe. Most pipe 1513 * users do not call fstat(2) on the pipe, which means that 1514 * postponing the inode allocation until it is must be 1515 * returned to userland is useful. If alloc_unr failed, 1516 * assign st_ino zero instead of returning an error. 1517 * Special pipe_ino values: 1518 * -1 - not yet initialized; 1519 * 0 - alloc_unr failed, return 0 as st_ino forever. 1520 */ 1521 if (pipe->pipe_ino == (ino_t)-1) { 1522 new_unr = alloc_unr(pipeino_unr); 1523 if (new_unr != -1) 1524 pipe->pipe_ino = new_unr; 1525 else 1526 pipe->pipe_ino = 0; 1527 } 1528 PIPE_UNLOCK(pipe); 1529 1530 bzero(ub, sizeof(*ub)); 1531 ub->st_mode = S_IFIFO; 1532 ub->st_blksize = PAGE_SIZE; 1533 if (pipe->pipe_state & PIPE_DIRECTW) 1534 ub->st_size = pipe->pipe_map.cnt; 1535 else 1536 ub->st_size = pipe->pipe_buffer.cnt; 1537 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize; 1538 ub->st_atim = pipe->pipe_atime; 1539 ub->st_mtim = pipe->pipe_mtime; 1540 ub->st_ctim = pipe->pipe_ctime; 1541 ub->st_uid = fp->f_cred->cr_uid; 1542 ub->st_gid = fp->f_cred->cr_gid; 1543 ub->st_dev = pipedev_ino; 1544 ub->st_ino = pipe->pipe_ino; 1545 /* 1546 * Left as 0: st_nlink, st_rdev, st_flags, st_gen. 1547 */ 1548 return (0); 1549} 1550 1551/* ARGSUSED */ 1552static int 1553pipe_close(fp, td) 1554 struct file *fp; 1555 struct thread *td; 1556{ 1557 1558 if (fp->f_vnode != NULL) 1559 return vnops.fo_close(fp, td); 1560 fp->f_ops = &badfileops; 1561 pipe_dtor(fp->f_data); 1562 fp->f_data = NULL; 1563 return (0); 1564} 1565 1566static int 1567pipe_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, struct thread *td) 1568{ 1569 struct pipe *cpipe; 1570 int error; 1571 1572 cpipe = fp->f_data; 1573 if (cpipe->pipe_state & PIPE_NAMED) 1574 error = vn_chmod(fp, mode, active_cred, td); 1575 else 1576 error = invfo_chmod(fp, mode, active_cred, td); 1577 return (error); 1578} 1579 1580static int 1581pipe_chown(fp, uid, gid, active_cred, td) 1582 struct file *fp; 1583 uid_t uid; 1584 gid_t gid; 1585 struct ucred *active_cred; 1586 struct thread *td; 1587{ 1588 struct pipe *cpipe; 1589 int error; 1590 1591 cpipe = fp->f_data; 1592 if (cpipe->pipe_state & PIPE_NAMED) 1593 error = vn_chown(fp, uid, gid, active_cred, td); 1594 else 1595 error = invfo_chown(fp, uid, gid, active_cred, td); 1596 return (error); 1597} 1598 1599static void 1600pipe_free_kmem(cpipe) 1601 struct pipe *cpipe; 1602{ 1603 1604 KASSERT(!mtx_owned(PIPE_MTX(cpipe)), 1605 ("pipe_free_kmem: pipe mutex locked")); 1606 1607 if (cpipe->pipe_buffer.buffer != NULL) { 1608 atomic_subtract_long(&amountpipekva, cpipe->pipe_buffer.size); 1609 vm_map_remove(pipe_map, 1610 (vm_offset_t)cpipe->pipe_buffer.buffer, 1611 (vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size); 1612 cpipe->pipe_buffer.buffer = NULL; 1613 } 1614#ifndef PIPE_NODIRECT 1615 { 1616 cpipe->pipe_map.cnt = 0; 1617 cpipe->pipe_map.pos = 0; 1618 cpipe->pipe_map.npages = 0; 1619 } 1620#endif 1621} 1622 1623/* 1624 * shutdown the pipe 1625 */ 1626static void 1627pipeclose(cpipe) 1628 struct pipe *cpipe; 1629{ 1630 struct pipepair *pp; 1631 struct pipe *ppipe; 1632 1633 KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL")); 1634 1635 PIPE_LOCK(cpipe); 1636 pipelock(cpipe, 0); 1637 pp = cpipe->pipe_pair; 1638 1639 pipeselwakeup(cpipe); 1640 1641 /* 1642 * If the other side is blocked, wake it up saying that 1643 * we want to close it down. 1644 */ 1645 cpipe->pipe_state |= PIPE_EOF; 1646 while (cpipe->pipe_busy) { 1647 wakeup(cpipe); 1648 cpipe->pipe_state |= PIPE_WANT; 1649 pipeunlock(cpipe); 1650 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0); 1651 pipelock(cpipe, 0); 1652 } 1653 1654 1655 /* 1656 * Disconnect from peer, if any. 1657 */ 1658 ppipe = cpipe->pipe_peer; 1659 if (ppipe->pipe_present == PIPE_ACTIVE) { 1660 pipeselwakeup(ppipe); 1661 1662 ppipe->pipe_state |= PIPE_EOF; 1663 wakeup(ppipe); 1664 KNOTE_LOCKED(&ppipe->pipe_sel.si_note, 0); 1665 } 1666 1667 /* 1668 * Mark this endpoint as free. Release kmem resources. We 1669 * don't mark this endpoint as unused until we've finished 1670 * doing that, or the pipe might disappear out from under 1671 * us. 1672 */ 1673 PIPE_UNLOCK(cpipe); 1674 pipe_free_kmem(cpipe); 1675 PIPE_LOCK(cpipe); 1676 cpipe->pipe_present = PIPE_CLOSING; 1677 pipeunlock(cpipe); 1678 1679 /* 1680 * knlist_clear() may sleep dropping the PIPE_MTX. Set the 1681 * PIPE_FINALIZED, that allows other end to free the 1682 * pipe_pair, only after the knotes are completely dismantled. 1683 */ 1684 knlist_clear(&cpipe->pipe_sel.si_note, 1); 1685 cpipe->pipe_present = PIPE_FINALIZED; 1686 seldrain(&cpipe->pipe_sel); 1687 knlist_destroy(&cpipe->pipe_sel.si_note); 1688 1689 /* 1690 * If both endpoints are now closed, release the memory for the 1691 * pipe pair. If not, unlock. 1692 */ 1693 if (ppipe->pipe_present == PIPE_FINALIZED) { 1694 PIPE_UNLOCK(cpipe); 1695#ifdef MAC 1696 mac_pipe_destroy(pp); 1697#endif 1698 uma_zfree(pipe_zone, cpipe->pipe_pair); 1699 } else 1700 PIPE_UNLOCK(cpipe); 1701} 1702 1703/*ARGSUSED*/ 1704static int 1705pipe_kqfilter(struct file *fp, struct knote *kn) 1706{ 1707 struct pipe *cpipe; 1708 1709 /* 1710 * If a filter is requested that is not supported by this file 1711 * descriptor, don't return an error, but also don't ever generate an 1712 * event. 1713 */ 1714 if ((kn->kn_filter == EVFILT_READ) && !(fp->f_flag & FREAD)) { 1715 kn->kn_fop = &pipe_nfiltops; 1716 return (0); 1717 } 1718 if ((kn->kn_filter == EVFILT_WRITE) && !(fp->f_flag & FWRITE)) { 1719 kn->kn_fop = &pipe_nfiltops; 1720 return (0); 1721 } 1722 cpipe = fp->f_data; 1723 PIPE_LOCK(cpipe); 1724 switch (kn->kn_filter) { 1725 case EVFILT_READ: 1726 kn->kn_fop = &pipe_rfiltops; 1727 break; 1728 case EVFILT_WRITE: 1729 kn->kn_fop = &pipe_wfiltops; 1730 if (cpipe->pipe_peer->pipe_present != PIPE_ACTIVE) { 1731 /* other end of pipe has been closed */ 1732 PIPE_UNLOCK(cpipe); 1733 return (EPIPE); 1734 } 1735 cpipe = PIPE_PEER(cpipe); 1736 break; 1737 default: 1738 PIPE_UNLOCK(cpipe); 1739 return (EINVAL); 1740 } 1741 1742 kn->kn_hook = cpipe; 1743 knlist_add(&cpipe->pipe_sel.si_note, kn, 1); 1744 PIPE_UNLOCK(cpipe); 1745 return (0); 1746} 1747 1748static void 1749filt_pipedetach(struct knote *kn) 1750{ 1751 struct pipe *cpipe = kn->kn_hook; 1752 1753 PIPE_LOCK(cpipe); 1754 knlist_remove(&cpipe->pipe_sel.si_note, kn, 1); 1755 PIPE_UNLOCK(cpipe); 1756} 1757 1758/*ARGSUSED*/ 1759static int 1760filt_piperead(struct knote *kn, long hint) 1761{ 1762 struct pipe *rpipe = kn->kn_hook; 1763 struct pipe *wpipe = rpipe->pipe_peer; 1764 int ret; 1765 1766 PIPE_LOCK(rpipe); 1767 kn->kn_data = rpipe->pipe_buffer.cnt; 1768 if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) 1769 kn->kn_data = rpipe->pipe_map.cnt; 1770 1771 if ((rpipe->pipe_state & PIPE_EOF) || 1772 wpipe->pipe_present != PIPE_ACTIVE || 1773 (wpipe->pipe_state & PIPE_EOF)) { 1774 kn->kn_flags |= EV_EOF; 1775 PIPE_UNLOCK(rpipe); 1776 return (1); 1777 } 1778 ret = kn->kn_data > 0; 1779 PIPE_UNLOCK(rpipe); 1780 return ret; 1781} 1782 1783/*ARGSUSED*/ 1784static int 1785filt_pipewrite(struct knote *kn, long hint) 1786{ 1787 struct pipe *wpipe; 1788 1789 wpipe = kn->kn_hook; 1790 PIPE_LOCK(wpipe); 1791 if (wpipe->pipe_present != PIPE_ACTIVE || 1792 (wpipe->pipe_state & PIPE_EOF)) { 1793 kn->kn_data = 0; 1794 kn->kn_flags |= EV_EOF; 1795 PIPE_UNLOCK(wpipe); 1796 return (1); 1797 } 1798 kn->kn_data = (wpipe->pipe_buffer.size > 0) ? 1799 (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) : PIPE_BUF; 1800 if (wpipe->pipe_state & PIPE_DIRECTW) 1801 kn->kn_data = 0; 1802 1803 PIPE_UNLOCK(wpipe); 1804 return (kn->kn_data >= PIPE_BUF); 1805} 1806 1807static void 1808filt_pipedetach_notsup(struct knote *kn) 1809{ 1810 1811} 1812 1813static int 1814filt_pipenotsup(struct knote *kn, long hint) 1815{ 1816 1817 return (0); 1818} 1819