fifo_vnops.c revision 259814
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 259814 2013-12-24 07:25:49Z kib $ 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 error = pipe_named_ctor(&fpipe, td); 150 if (error != 0) 151 return (error); 152 fip = malloc(sizeof(*fip), M_VNODE, M_WAITOK); 153 fip->fi_pipe = fpipe; 154 fpipe->pipe_wgen = fip->fi_readers = fip->fi_writers = 0; 155 KASSERT(vp->v_fifoinfo == NULL, ("fifo_open: v_fifoinfo race")); 156 vp->v_fifoinfo = fip; 157 } 158 fpipe = fip->fi_pipe; 159 KASSERT(fpipe != NULL, ("fifo_open: pipe is NULL")); 160 161 /* 162 * Use the pipe mutex here, in addition to the vnode lock, 163 * in order to allow vnode lock dropping before msleep() calls 164 * and still avoiding missed wakeups. 165 */ 166 PIPE_LOCK(fpipe); 167 if (ap->a_mode & FREAD) { 168 fip->fi_readers++; 169 if (fip->fi_readers == 1) { 170 fpipe->pipe_state &= ~PIPE_EOF; 171 if (fip->fi_writers > 0) 172 wakeup(&fip->fi_writers); 173 } 174 fp->f_seqcount = fpipe->pipe_wgen - fip->fi_writers; 175 } 176 if (ap->a_mode & FWRITE) { 177 if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) { 178 PIPE_UNLOCK(fpipe); 179 if (fip->fi_writers == 0) 180 fifo_cleanup(vp); 181 return (ENXIO); 182 } 183 fip->fi_writers++; 184 if (fip->fi_writers == 1) { 185 fpipe->pipe_state &= ~PIPE_EOF; 186 if (fip->fi_readers > 0) 187 wakeup(&fip->fi_readers); 188 } 189 } 190 if ((ap->a_mode & O_NONBLOCK) == 0) { 191 if ((ap->a_mode & FREAD) && fip->fi_writers == 0) { 192 VOP_UNLOCK(vp, 0); 193 error = msleep(&fip->fi_readers, PIPE_MTX(fpipe), 194 PDROP | PCATCH | PSOCK, "fifoor", 0); 195 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 196 if (error) { 197 fip->fi_readers--; 198 if (fip->fi_readers == 0) { 199 PIPE_LOCK(fpipe); 200 fpipe->pipe_state |= PIPE_EOF; 201 if (fpipe->pipe_state & PIPE_WANTW) 202 wakeup(fpipe); 203 PIPE_UNLOCK(fpipe); 204 fifo_cleanup(vp); 205 } 206 return (error); 207 } 208 PIPE_LOCK(fpipe); 209 /* 210 * We must have got woken up because we had a writer. 211 * That (and not still having one) is the condition 212 * that we must wait for. 213 */ 214 } 215 if ((ap->a_mode & FWRITE) && fip->fi_readers == 0) { 216 VOP_UNLOCK(vp, 0); 217 error = msleep(&fip->fi_writers, PIPE_MTX(fpipe), 218 PDROP | PCATCH | PSOCK, "fifoow", 0); 219 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 220 if (error) { 221 fip->fi_writers--; 222 if (fip->fi_writers == 0) { 223 PIPE_LOCK(fpipe); 224 fpipe->pipe_state |= PIPE_EOF; 225 if (fpipe->pipe_state & PIPE_WANTR) 226 wakeup(fpipe); 227 fpipe->pipe_wgen++; 228 PIPE_UNLOCK(fpipe); 229 fifo_cleanup(vp); 230 } 231 return (error); 232 } 233 /* 234 * We must have got woken up because we had 235 * a reader. That (and not still having one) 236 * is the condition that we must wait for. 237 */ 238 PIPE_LOCK(fpipe); 239 } 240 } 241 PIPE_UNLOCK(fpipe); 242 KASSERT(fp != NULL, ("can't fifo/vnode bypass")); 243 KASSERT(fp->f_ops == &badfileops, ("not badfileops in fifo_open")); 244 finit(fp, fp->f_flag, DTYPE_FIFO, fpipe, &pipeops); 245 return (0); 246} 247 248/* 249 * Device close routine 250 */ 251/* ARGSUSED */ 252static int 253fifo_close(ap) 254 struct vop_close_args /* { 255 struct vnode *a_vp; 256 int a_fflag; 257 struct ucred *a_cred; 258 struct thread *a_td; 259 } */ *ap; 260{ 261 struct vnode *vp; 262 struct fifoinfo *fip; 263 struct pipe *cpipe; 264 265 vp = ap->a_vp; 266 fip = vp->v_fifoinfo; 267 cpipe = fip->fi_pipe; 268 ASSERT_VOP_ELOCKED(vp, "fifo_close"); 269 if (ap->a_fflag & FREAD) { 270 fip->fi_readers--; 271 if (fip->fi_readers == 0) { 272 PIPE_LOCK(cpipe); 273 cpipe->pipe_state |= PIPE_EOF; 274 if ((cpipe->pipe_state & PIPE_WANTW)) { 275 cpipe->pipe_state &= ~PIPE_WANTW; 276 wakeup(cpipe); 277 } 278 pipeselwakeup(cpipe); 279 PIPE_UNLOCK(cpipe); 280 } 281 } 282 if (ap->a_fflag & FWRITE) { 283 fip->fi_writers--; 284 if (fip->fi_writers == 0) { 285 PIPE_LOCK(cpipe); 286 cpipe->pipe_state |= PIPE_EOF; 287 if ((cpipe->pipe_state & PIPE_WANTR)) { 288 cpipe->pipe_state &= ~PIPE_WANTR; 289 wakeup(cpipe); 290 } 291 cpipe->pipe_wgen++; 292 pipeselwakeup(cpipe); 293 PIPE_UNLOCK(cpipe); 294 } 295 } 296 fifo_cleanup(vp); 297 return (0); 298} 299 300/* 301 * Print out internal contents of a fifo vnode. 302 */ 303int 304fifo_printinfo(vp) 305 struct vnode *vp; 306{ 307 register struct fifoinfo *fip = vp->v_fifoinfo; 308 309 if (fip == NULL){ 310 printf(", NULL v_fifoinfo"); 311 return (0); 312 } 313 printf(", fifo with %ld readers and %ld writers", 314 fip->fi_readers, fip->fi_writers); 315 return (0); 316} 317 318/* 319 * Print out the contents of a fifo vnode. 320 */ 321static int 322fifo_print(ap) 323 struct vop_print_args /* { 324 struct vnode *a_vp; 325 } */ *ap; 326{ 327 printf(" "); 328 fifo_printinfo(ap->a_vp); 329 printf("\n"); 330 return (0); 331} 332 333/* 334 * Return POSIX pathconf information applicable to fifo's. 335 */ 336static int 337fifo_pathconf(ap) 338 struct vop_pathconf_args /* { 339 struct vnode *a_vp; 340 int a_name; 341 int *a_retval; 342 } */ *ap; 343{ 344 345 switch (ap->a_name) { 346 case _PC_LINK_MAX: 347 *ap->a_retval = LINK_MAX; 348 return (0); 349 case _PC_PIPE_BUF: 350 *ap->a_retval = PIPE_BUF; 351 return (0); 352 case _PC_CHOWN_RESTRICTED: 353 *ap->a_retval = 1; 354 return (0); 355 default: 356 return (EINVAL); 357 } 358 /* NOTREACHED */ 359} 360 361/* 362 * Fifo advisory byte-level locks. 363 */ 364/* ARGSUSED */ 365static int 366fifo_advlock(ap) 367 struct vop_advlock_args /* { 368 struct vnode *a_vp; 369 caddr_t a_id; 370 int a_op; 371 struct flock *a_fl; 372 int a_flags; 373 } */ *ap; 374{ 375 376 return (ap->a_flags & F_FLOCK ? EOPNOTSUPP : EINVAL); 377} 378 379