1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1990, 1993, 1995 5 * The Regents of the University of California. 6 * Copyright (c) 2005 Robert N. M. Watson 7 * Copyright (c) 2012 Giovanni Trematerra 8 * All rights reserved. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)fifo_vnops.c 8.10 (Berkeley) 5/27/95 35 * $FreeBSD$ 36 */ 37 38 #include <sys/param.h> 39 #include <sys/event.h> 40 #include <sys/file.h> 41 #include <sys/filedesc.h> 42 #include <sys/filio.h> 43 #include <sys/fcntl.h> 44 #include <sys/kernel.h> 45 #include <sys/lock.h> 46 #include <sys/mutex.h> 47 #include <sys/malloc.h> 48 #include <sys/selinfo.h> 49 #include <sys/pipe.h> 50 #include <sys/proc.h> 51 #include <sys/signalvar.h> 52 #include <sys/sx.h> 53 #include <sys/systm.h> 54 #include <sys/un.h> 55 #include <sys/unistd.h> 56 #include <sys/vnode.h> 57 58 /* 59 * This structure is associated with the FIFO vnode and stores 60 * the state associated with the FIFO. 61 * Notes about locking: 62 * - fi_pipe is invariant since init time. 63 * - fi_readers and fi_writers are protected by the vnode lock. 64 */ 65 struct fifoinfo { 66 struct pipe *fi_pipe; 67 long fi_readers; 68 long fi_writers; 69 u_int fi_rgen; 70 u_int fi_wgen; 71 }; 72 73 static vop_print_t fifo_print; 74 static vop_open_t fifo_open; 75 static vop_close_t fifo_close; 76 static vop_advlock_t fifo_advlock; 77 78 struct vop_vector fifo_specops = { 79 .vop_default = &default_vnodeops, 80 81 .vop_advlock = fifo_advlock, 82 .vop_close = fifo_close, 83 .vop_create = VOP_PANIC, 84 .vop_getattr = VOP_EBADF, 85 .vop_ioctl = VOP_PANIC, 86 .vop_kqfilter = VOP_PANIC, 87 .vop_link = VOP_PANIC, 88 .vop_mkdir = VOP_PANIC, 89 .vop_mknod = VOP_PANIC, 90 .vop_open = fifo_open, 91 .vop_pathconf = VOP_PANIC, 92 .vop_print = fifo_print, 93 .vop_read = VOP_PANIC, 94 .vop_readdir = VOP_PANIC, 95 .vop_readlink = VOP_PANIC, 96 .vop_reallocblks = VOP_PANIC, 97 .vop_reclaim = VOP_NULL, 98 .vop_remove = VOP_PANIC, 99 .vop_rename = VOP_PANIC, 100 .vop_rmdir = VOP_PANIC, 101 .vop_setattr = VOP_EBADF, 102 .vop_symlink = VOP_PANIC, 103 .vop_write = VOP_PANIC, 104 }; 105 VFS_VOP_VECTOR_REGISTER(fifo_specops); 106 107 /* 108 * Dispose of fifo resources. 109 */ 110 static void 111 fifo_cleanup(struct vnode *vp) 112 { 113 struct fifoinfo *fip; 114 115 ASSERT_VOP_ELOCKED(vp, "fifo_cleanup"); 116 fip = vp->v_fifoinfo; 117 if (fip->fi_readers == 0 && fip->fi_writers == 0) { 118 vp->v_fifoinfo = NULL; 119 pipe_dtor(fip->fi_pipe); 120 free(fip, M_VNODE); 121 } 122 } 123 124 /* 125 * Open called to set up a new instance of a fifo or 126 * to find an active instance of a fifo. 127 */ 128 /* ARGSUSED */ 129 static int 130 fifo_open(ap) 131 struct vop_open_args /* { 132 struct vnode *a_vp; 133 int a_mode; 134 struct ucred *a_cred; 135 struct thread *a_td; 136 struct file *a_fp; 137 } */ *ap; 138 { 139 struct vnode *vp; 140 struct file *fp; 141 struct thread *td; 142 struct fifoinfo *fip; 143 struct pipe *fpipe; 144 u_int gen; 145 int error, stops_deferred; 146 147 vp = ap->a_vp; 148 fp = ap->a_fp; 149 td = ap->a_td; 150 ASSERT_VOP_ELOCKED(vp, "fifo_open"); 151 if (fp == NULL || (ap->a_mode & FEXEC) != 0) 152 return (EINVAL); 153 if ((fip = vp->v_fifoinfo) == NULL) { 154 error = pipe_named_ctor(&fpipe, td); 155 if (error != 0) 156 return (error); 157 fip = malloc(sizeof(*fip), M_VNODE, M_WAITOK | M_ZERO); 158 fip->fi_pipe = fpipe; 159 fpipe->pipe_wgen = 0; 160 KASSERT(vp->v_fifoinfo == NULL, ("fifo_open: v_fifoinfo race")); 161 vp->v_fifoinfo = fip; 162 } 163 fpipe = fip->fi_pipe; 164 KASSERT(fpipe != NULL, ("fifo_open: pipe is NULL")); 165 166 /* 167 * Use the pipe mutex here, in addition to the vnode lock, 168 * in order to allow vnode lock dropping before msleep() calls 169 * and still avoiding missed wakeups. 170 */ 171 PIPE_LOCK(fpipe); 172 if (ap->a_mode & FREAD) { 173 fip->fi_readers++; 174 fip->fi_rgen++; 175 if (fip->fi_readers == 1) { 176 fpipe->pipe_state &= ~PIPE_EOF; 177 if (fip->fi_writers > 0) { 178 wakeup(&fip->fi_writers); 179 pipeselwakeup(fpipe); 180 } 181 } 182 fp->f_pipegen = fpipe->pipe_wgen - fip->fi_writers; 183 } 184 if (ap->a_mode & FWRITE) { 185 if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) { 186 PIPE_UNLOCK(fpipe); 187 if (fip->fi_writers == 0) 188 fifo_cleanup(vp); 189 return (ENXIO); 190 } 191 fip->fi_writers++; 192 fip->fi_wgen++; 193 if (fip->fi_writers == 1) { 194 fpipe->pipe_state &= ~PIPE_EOF; 195 if (fip->fi_readers > 0) { 196 wakeup(&fip->fi_readers); 197 pipeselwakeup(fpipe); 198 } 199 } 200 } 201 if ((ap->a_mode & O_NONBLOCK) == 0) { 202 if ((ap->a_mode & FREAD) && fip->fi_writers == 0) { 203 gen = fip->fi_wgen; 204 VOP_UNLOCK(vp); 205 stops_deferred = sigdeferstop(SIGDEFERSTOP_OFF); 206 error = msleep(&fip->fi_readers, PIPE_MTX(fpipe), 207 PDROP | PCATCH | PSOCK, "fifoor", 0); 208 sigallowstop(stops_deferred); 209 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 210 if (error != 0 && gen == fip->fi_wgen) { 211 fip->fi_readers--; 212 if (fip->fi_readers == 0) { 213 PIPE_LOCK(fpipe); 214 fpipe->pipe_state |= PIPE_EOF; 215 if (fpipe->pipe_state & PIPE_WANTW) 216 wakeup(fpipe); 217 pipeselwakeup(fpipe); 218 PIPE_UNLOCK(fpipe); 219 fifo_cleanup(vp); 220 } 221 return (error); 222 } 223 PIPE_LOCK(fpipe); 224 /* 225 * We must have got woken up because we had a writer. 226 * That (and not still having one) is the condition 227 * that we must wait for. 228 */ 229 } 230 if ((ap->a_mode & FWRITE) && fip->fi_readers == 0) { 231 gen = fip->fi_rgen; 232 VOP_UNLOCK(vp); 233 stops_deferred = sigdeferstop(SIGDEFERSTOP_OFF); 234 error = msleep(&fip->fi_writers, PIPE_MTX(fpipe), 235 PDROP | PCATCH | PSOCK, "fifoow", 0); 236 sigallowstop(stops_deferred); 237 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 238 if (error != 0 && gen == fip->fi_rgen) { 239 fip->fi_writers--; 240 if (fip->fi_writers == 0) { 241 PIPE_LOCK(fpipe); 242 fpipe->pipe_state |= PIPE_EOF; 243 if (fpipe->pipe_state & PIPE_WANTR) 244 wakeup(fpipe); 245 fpipe->pipe_wgen++; 246 pipeselwakeup(fpipe); 247 PIPE_UNLOCK(fpipe); 248 fifo_cleanup(vp); 249 } 250 return (error); 251 } 252 /* 253 * We must have got woken up because we had 254 * a reader. That (and not still having one) 255 * is the condition that we must wait for. 256 */ 257 PIPE_LOCK(fpipe); 258 } 259 } 260 PIPE_UNLOCK(fpipe); 261 KASSERT(fp != NULL, ("can't fifo/vnode bypass")); 262 KASSERT(fp->f_ops == &badfileops, ("not badfileops in fifo_open")); 263 finit(fp, fp->f_flag, DTYPE_FIFO, fpipe, &pipeops); 264 return (0); 265 } 266 267 /* 268 * Device close routine 269 */ 270 /* ARGSUSED */ 271 static int 272 fifo_close(ap) 273 struct vop_close_args /* { 274 struct vnode *a_vp; 275 int a_fflag; 276 struct ucred *a_cred; 277 struct thread *a_td; 278 } */ *ap; 279 { 280 struct vnode *vp; 281 struct fifoinfo *fip; 282 struct pipe *cpipe; 283 284 vp = ap->a_vp; 285 ASSERT_VOP_ELOCKED(vp, "fifo_close"); 286 fip = vp->v_fifoinfo; 287 288 /* 289 * During open, it is possible that the fifo vnode is relocked 290 * after the vnode is instantiated but before VOP_OPEN() is 291 * done. For instance, vn_open_vnode() might need to upgrade 292 * vnode lock, or ffs_vput_pair() needs to unlock vp to sync 293 * dvp. In this case, reclaim can observe us with v_fifoinfo 294 * equal to NULL. 295 */ 296 if (fip == NULL) 297 return (0); 298 299 cpipe = fip->fi_pipe; 300 if (ap->a_fflag & FREAD) { 301 fip->fi_readers--; 302 if (fip->fi_readers == 0) { 303 PIPE_LOCK(cpipe); 304 cpipe->pipe_state |= PIPE_EOF; 305 if ((cpipe->pipe_state & PIPE_WANTW)) { 306 cpipe->pipe_state &= ~PIPE_WANTW; 307 wakeup(cpipe); 308 } 309 pipeselwakeup(cpipe); 310 PIPE_UNLOCK(cpipe); 311 } 312 } 313 if (ap->a_fflag & FWRITE) { 314 fip->fi_writers--; 315 if (fip->fi_writers == 0) { 316 PIPE_LOCK(cpipe); 317 cpipe->pipe_state |= PIPE_EOF; 318 if ((cpipe->pipe_state & PIPE_WANTR)) { 319 cpipe->pipe_state &= ~PIPE_WANTR; 320 wakeup(cpipe); 321 } 322 cpipe->pipe_wgen++; 323 pipeselwakeup(cpipe); 324 PIPE_UNLOCK(cpipe); 325 } 326 } 327 fifo_cleanup(vp); 328 return (0); 329 } 330 331 /* 332 * Print out internal contents of a fifo vnode. 333 */ 334 int 335 fifo_printinfo(vp) 336 struct vnode *vp; 337 { 338 struct fifoinfo *fip = vp->v_fifoinfo; 339 340 if (fip == NULL){ 341 printf(", NULL v_fifoinfo"); 342 return (0); 343 } 344 printf(", fifo with %ld readers and %ld writers", 345 fip->fi_readers, fip->fi_writers); 346 return (0); 347 } 348 349 /* 350 * Print out the contents of a fifo vnode. 351 */ 352 static int 353 fifo_print(ap) 354 struct vop_print_args /* { 355 struct vnode *a_vp; 356 } */ *ap; 357 { 358 printf(" "); 359 fifo_printinfo(ap->a_vp); 360 printf("\n"); 361 return (0); 362 } 363 364 /* 365 * Fifo advisory byte-level locks. 366 */ 367 /* ARGSUSED */ 368 static int 369 fifo_advlock(ap) 370 struct vop_advlock_args /* { 371 struct vnode *a_vp; 372 caddr_t a_id; 373 int a_op; 374 struct flock *a_fl; 375 int a_flags; 376 } */ *ap; 377 { 378 379 return (ap->a_flags & F_FLOCK ? EOPNOTSUPP : EINVAL); 380 } 381