fifo_vnops.c revision 268335
1/*- 2 * Copyright (c) 1990, 1993, 1995 3 * The Regents of the University of California. 4 * Copyright (c) 2005 Robert N. M. Watson 5 * Copyright (c) 2012 Giovanni Trematerra 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)fifo_vnops.c 8.10 (Berkeley) 5/27/95 33 * $FreeBSD: stable/10/sys/fs/fifofs/fifo_vnops.c 268335 2014-07-06 22:47:18Z mjg $ 34 */ 35 36#include <sys/param.h> 37#include <sys/event.h> 38#include <sys/file.h> 39#include <sys/filedesc.h> 40#include <sys/filio.h> 41#include <sys/fcntl.h> 42#include <sys/kernel.h> 43#include <sys/lock.h> 44#include <sys/mutex.h> 45#include <sys/malloc.h> 46#include <sys/selinfo.h> 47#include <sys/pipe.h> 48#include <sys/proc.h> 49#include <sys/signalvar.h> 50#include <sys/sx.h> 51#include <sys/systm.h> 52#include <sys/un.h> 53#include <sys/unistd.h> 54#include <sys/vnode.h> 55 56/* 57 * This structure is associated with the FIFO vnode and stores 58 * the state associated with the FIFO. 59 * Notes about locking: 60 * - fi_pipe is invariant since init time. 61 * - fi_readers and fi_writers are protected by the vnode lock. 62 */ 63struct fifoinfo { 64 struct pipe *fi_pipe; 65 long fi_readers; 66 long fi_writers; 67}; 68 69static vop_print_t fifo_print; 70static vop_open_t fifo_open; 71static vop_close_t fifo_close; 72static vop_pathconf_t fifo_pathconf; 73static vop_advlock_t fifo_advlock; 74 75struct vop_vector fifo_specops = { 76 .vop_default = &default_vnodeops, 77 78 .vop_advlock = fifo_advlock, 79 .vop_close = fifo_close, 80 .vop_create = VOP_PANIC, 81 .vop_getattr = VOP_EBADF, 82 .vop_ioctl = VOP_PANIC, 83 .vop_kqfilter = VOP_PANIC, 84 .vop_link = VOP_PANIC, 85 .vop_mkdir = VOP_PANIC, 86 .vop_mknod = VOP_PANIC, 87 .vop_open = fifo_open, 88 .vop_pathconf = fifo_pathconf, 89 .vop_print = fifo_print, 90 .vop_read = VOP_PANIC, 91 .vop_readdir = VOP_PANIC, 92 .vop_readlink = VOP_PANIC, 93 .vop_reallocblks = VOP_PANIC, 94 .vop_reclaim = VOP_NULL, 95 .vop_remove = VOP_PANIC, 96 .vop_rename = VOP_PANIC, 97 .vop_rmdir = VOP_PANIC, 98 .vop_setattr = VOP_EBADF, 99 .vop_symlink = VOP_PANIC, 100 .vop_write = VOP_PANIC, 101}; 102 103/* 104 * Dispose of fifo resources. 105 */ 106static void 107fifo_cleanup(struct vnode *vp) 108{ 109 struct fifoinfo *fip; 110 111 ASSERT_VOP_ELOCKED(vp, "fifo_cleanup"); 112 fip = vp->v_fifoinfo; 113 if (fip->fi_readers == 0 && fip->fi_writers == 0) { 114 vp->v_fifoinfo = NULL; 115 pipe_dtor(fip->fi_pipe); 116 free(fip, M_VNODE); 117 } 118} 119 120/* 121 * Open called to set up a new instance of a fifo or 122 * to find an active instance of a fifo. 123 */ 124/* ARGSUSED */ 125static int 126fifo_open(ap) 127 struct vop_open_args /* { 128 struct vnode *a_vp; 129 int a_mode; 130 struct ucred *a_cred; 131 struct thread *a_td; 132 struct file *a_fp; 133 } */ *ap; 134{ 135 struct vnode *vp; 136 struct file *fp; 137 struct thread *td; 138 struct fifoinfo *fip; 139 struct pipe *fpipe; 140 int error; 141 142 vp = ap->a_vp; 143 fp = ap->a_fp; 144 td = ap->a_td; 145 ASSERT_VOP_ELOCKED(vp, "fifo_open"); 146 if (fp == NULL || (ap->a_mode & FEXEC) != 0) 147 return (EINVAL); 148 if ((fip = vp->v_fifoinfo) == NULL) { 149 pipe_named_ctor(&fpipe, td); 150 fip = malloc(sizeof(*fip), M_VNODE, M_WAITOK); 151 fip->fi_pipe = fpipe; 152 fpipe->pipe_wgen = fip->fi_readers = fip->fi_writers = 0; 153 KASSERT(vp->v_fifoinfo == NULL, ("fifo_open: v_fifoinfo race")); 154 vp->v_fifoinfo = fip; 155 } 156 fpipe = fip->fi_pipe; 157 KASSERT(fpipe != NULL, ("fifo_open: pipe is NULL")); 158 159 /* 160 * Use the pipe mutex here, in addition to the vnode lock, 161 * in order to allow vnode lock dropping before msleep() calls 162 * and still avoiding missed wakeups. 163 */ 164 PIPE_LOCK(fpipe); 165 if (ap->a_mode & FREAD) { 166 fip->fi_readers++; 167 if (fip->fi_readers == 1) { 168 fpipe->pipe_state &= ~PIPE_EOF; 169 if (fip->fi_writers > 0) 170 wakeup(&fip->fi_writers); 171 } 172 fp->f_seqcount = fpipe->pipe_wgen - fip->fi_writers; 173 } 174 if (ap->a_mode & FWRITE) { 175 if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) { 176 PIPE_UNLOCK(fpipe); 177 if (fip->fi_writers == 0) 178 fifo_cleanup(vp); 179 return (ENXIO); 180 } 181 fip->fi_writers++; 182 if (fip->fi_writers == 1) { 183 fpipe->pipe_state &= ~PIPE_EOF; 184 if (fip->fi_readers > 0) 185 wakeup(&fip->fi_readers); 186 } 187 } 188 if ((ap->a_mode & O_NONBLOCK) == 0) { 189 if ((ap->a_mode & FREAD) && fip->fi_writers == 0) { 190 VOP_UNLOCK(vp, 0); 191 error = msleep(&fip->fi_readers, PIPE_MTX(fpipe), 192 PDROP | PCATCH | PSOCK, "fifoor", 0); 193 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 194 if (error) { 195 fip->fi_readers--; 196 if (fip->fi_readers == 0) { 197 PIPE_LOCK(fpipe); 198 fpipe->pipe_state |= PIPE_EOF; 199 if (fpipe->pipe_state & PIPE_WANTW) 200 wakeup(fpipe); 201 PIPE_UNLOCK(fpipe); 202 fifo_cleanup(vp); 203 } 204 return (error); 205 } 206 PIPE_LOCK(fpipe); 207 /* 208 * We must have got woken up because we had a writer. 209 * That (and not still having one) is the condition 210 * that we must wait for. 211 */ 212 } 213 if ((ap->a_mode & FWRITE) && fip->fi_readers == 0) { 214 VOP_UNLOCK(vp, 0); 215 error = msleep(&fip->fi_writers, PIPE_MTX(fpipe), 216 PDROP | PCATCH | PSOCK, "fifoow", 0); 217 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 218 if (error) { 219 fip->fi_writers--; 220 if (fip->fi_writers == 0) { 221 PIPE_LOCK(fpipe); 222 fpipe->pipe_state |= PIPE_EOF; 223 if (fpipe->pipe_state & PIPE_WANTR) 224 wakeup(fpipe); 225 fpipe->pipe_wgen++; 226 PIPE_UNLOCK(fpipe); 227 fifo_cleanup(vp); 228 } 229 return (error); 230 } 231 /* 232 * We must have got woken up because we had 233 * a reader. That (and not still having one) 234 * is the condition that we must wait for. 235 */ 236 PIPE_LOCK(fpipe); 237 } 238 } 239 PIPE_UNLOCK(fpipe); 240 KASSERT(fp != NULL, ("can't fifo/vnode bypass")); 241 KASSERT(fp->f_ops == &badfileops, ("not badfileops in fifo_open")); 242 finit(fp, fp->f_flag, DTYPE_FIFO, fpipe, &pipeops); 243 return (0); 244} 245 246/* 247 * Device close routine 248 */ 249/* ARGSUSED */ 250static int 251fifo_close(ap) 252 struct vop_close_args /* { 253 struct vnode *a_vp; 254 int a_fflag; 255 struct ucred *a_cred; 256 struct thread *a_td; 257 } */ *ap; 258{ 259 struct vnode *vp; 260 struct fifoinfo *fip; 261 struct pipe *cpipe; 262 263 vp = ap->a_vp; 264 fip = vp->v_fifoinfo; 265 cpipe = fip->fi_pipe; 266 ASSERT_VOP_ELOCKED(vp, "fifo_close"); 267 if (ap->a_fflag & FREAD) { 268 fip->fi_readers--; 269 if (fip->fi_readers == 0) { 270 PIPE_LOCK(cpipe); 271 cpipe->pipe_state |= PIPE_EOF; 272 if ((cpipe->pipe_state & PIPE_WANTW)) { 273 cpipe->pipe_state &= ~PIPE_WANTW; 274 wakeup(cpipe); 275 } 276 pipeselwakeup(cpipe); 277 PIPE_UNLOCK(cpipe); 278 } 279 } 280 if (ap->a_fflag & FWRITE) { 281 fip->fi_writers--; 282 if (fip->fi_writers == 0) { 283 PIPE_LOCK(cpipe); 284 cpipe->pipe_state |= PIPE_EOF; 285 if ((cpipe->pipe_state & PIPE_WANTR)) { 286 cpipe->pipe_state &= ~PIPE_WANTR; 287 wakeup(cpipe); 288 } 289 cpipe->pipe_wgen++; 290 pipeselwakeup(cpipe); 291 PIPE_UNLOCK(cpipe); 292 } 293 } 294 fifo_cleanup(vp); 295 return (0); 296} 297 298/* 299 * Print out internal contents of a fifo vnode. 300 */ 301int 302fifo_printinfo(vp) 303 struct vnode *vp; 304{ 305 register struct fifoinfo *fip = vp->v_fifoinfo; 306 307 if (fip == NULL){ 308 printf(", NULL v_fifoinfo"); 309 return (0); 310 } 311 printf(", fifo with %ld readers and %ld writers", 312 fip->fi_readers, fip->fi_writers); 313 return (0); 314} 315 316/* 317 * Print out the contents of a fifo vnode. 318 */ 319static int 320fifo_print(ap) 321 struct vop_print_args /* { 322 struct vnode *a_vp; 323 } */ *ap; 324{ 325 printf(" "); 326 fifo_printinfo(ap->a_vp); 327 printf("\n"); 328 return (0); 329} 330 331/* 332 * Return POSIX pathconf information applicable to fifo's. 333 */ 334static int 335fifo_pathconf(ap) 336 struct vop_pathconf_args /* { 337 struct vnode *a_vp; 338 int a_name; 339 int *a_retval; 340 } */ *ap; 341{ 342 343 switch (ap->a_name) { 344 case _PC_LINK_MAX: 345 *ap->a_retval = LINK_MAX; 346 return (0); 347 case _PC_PIPE_BUF: 348 *ap->a_retval = PIPE_BUF; 349 return (0); 350 case _PC_CHOWN_RESTRICTED: 351 *ap->a_retval = 1; 352 return (0); 353 default: 354 return (EINVAL); 355 } 356 /* NOTREACHED */ 357} 358 359/* 360 * Fifo advisory byte-level locks. 361 */ 362/* ARGSUSED */ 363static int 364fifo_advlock(ap) 365 struct vop_advlock_args /* { 366 struct vnode *a_vp; 367 caddr_t a_id; 368 int a_op; 369 struct flock *a_fl; 370 int a_flags; 371 } */ *ap; 372{ 373 374 return (ap->a_flags & F_FLOCK ? EOPNOTSUPP : EINVAL); 375} 376 377