Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/fs/fdescfs/fdesc_vnops.c
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1 /*- 2 * Copyright (c) 1992, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software donated to Berkeley by 6 * Jan-Simon Pendry. 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 * @(#)fdesc_vnops.c 8.9 (Berkeley) 1/21/94 33 * 34 * $FreeBSD$ 35 */ 36 37 /* 38 * /dev/fd Filesystem 39 */ 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/capsicum.h> 44 #include <sys/conf.h> 45 #include <sys/dirent.h> 46 #include <sys/filedesc.h> 47 #include <sys/kernel.h> /* boottime */ 48 #include <sys/lock.h> 49 #include <sys/mutex.h> 50 #include <sys/malloc.h> 51 #include <sys/file.h> /* Must come after sys/malloc.h */ 52 #include <sys/mount.h> 53 #include <sys/namei.h> 54 #include <sys/proc.h> 55 #include <sys/stat.h> 56 #include <sys/vnode.h> 57 58 #include <fs/fdescfs/fdesc.h> 59 60 #define NFDCACHE 4 61 #define FD_NHASH(ix) \ 62 (&fdhashtbl[(ix) & fdhash]) 63 static LIST_HEAD(fdhashhead, fdescnode) *fdhashtbl; 64 static u_long fdhash; 65 66 struct mtx fdesc_hashmtx; 67 68 static vop_getattr_t fdesc_getattr; 69 static vop_lookup_t fdesc_lookup; 70 static vop_open_t fdesc_open; 71 static vop_readdir_t fdesc_readdir; 72 static vop_reclaim_t fdesc_reclaim; 73 static vop_setattr_t fdesc_setattr; 74 75 static struct vop_vector fdesc_vnodeops = { 76 .vop_default = &default_vnodeops, 77 78 .vop_access = VOP_NULL, 79 .vop_getattr = fdesc_getattr, 80 .vop_lookup = fdesc_lookup, 81 .vop_open = fdesc_open, 82 .vop_pathconf = vop_stdpathconf, 83 .vop_readdir = fdesc_readdir, 84 .vop_reclaim = fdesc_reclaim, 85 .vop_setattr = fdesc_setattr, 86 }; 87 88 static void fdesc_insmntque_dtr(struct vnode *, void *); 89 static void fdesc_remove_entry(struct fdescnode *); 90 91 /* 92 * Initialise cache headers 93 */ 94 int 95 fdesc_init(vfsp) 96 struct vfsconf *vfsp; 97 { 98 99 mtx_init(&fdesc_hashmtx, "fdescfs_hash", NULL, MTX_DEF); 100 fdhashtbl = hashinit(NFDCACHE, M_CACHE, &fdhash); 101 return (0); 102 } 103 104 /* 105 * Uninit ready for unload. 106 */ 107 int 108 fdesc_uninit(vfsp) 109 struct vfsconf *vfsp; 110 { 111 112 hashdestroy(fdhashtbl, M_CACHE, fdhash); 113 mtx_destroy(&fdesc_hashmtx); 114 return (0); 115 } 116 117 /* 118 * If allocating vnode fails, call this. 119 */ 120 static void 121 fdesc_insmntque_dtr(struct vnode *vp, void *arg) 122 { 123 124 vgone(vp); 125 vput(vp); 126 } 127 128 /* 129 * Remove an entry from the hash if it exists. 130 */ 131 static void 132 fdesc_remove_entry(struct fdescnode *fd) 133 { 134 struct fdhashhead *fc; 135 struct fdescnode *fd2; 136 137 fc = FD_NHASH(fd->fd_ix); 138 mtx_lock(&fdesc_hashmtx); 139 LIST_FOREACH(fd2, fc, fd_hash) { 140 if (fd == fd2) { 141 LIST_REMOVE(fd, fd_hash); 142 break; 143 } 144 } 145 mtx_unlock(&fdesc_hashmtx); 146 } 147 148 int 149 fdesc_allocvp(ftype, fd_fd, ix, mp, vpp) 150 fdntype ftype; 151 unsigned fd_fd; 152 int ix; 153 struct mount *mp; 154 struct vnode **vpp; 155 { 156 struct fdescmount *fmp; 157 struct fdhashhead *fc; 158 struct fdescnode *fd, *fd2; 159 struct vnode *vp, *vp2; 160 struct thread *td; 161 int error = 0; 162 163 td = curthread; 164 fc = FD_NHASH(ix); 165 loop: 166 mtx_lock(&fdesc_hashmtx); 167 /* 168 * If a forced unmount is progressing, we need to drop it. The flags are 169 * protected by the hashmtx. 170 */ 171 fmp = (struct fdescmount *)mp->mnt_data; 172 if (fmp == NULL || fmp->flags & FMNT_UNMOUNTF) { 173 mtx_unlock(&fdesc_hashmtx); 174 return (-1); 175 } 176 177 LIST_FOREACH(fd, fc, fd_hash) { 178 if (fd->fd_ix == ix && fd->fd_vnode->v_mount == mp) { 179 /* Get reference to vnode in case it's being free'd */ 180 vp = fd->fd_vnode; 181 VI_LOCK(vp); 182 mtx_unlock(&fdesc_hashmtx); 183 if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, td)) 184 goto loop; 185 *vpp = vp; 186 return (0); 187 } 188 } 189 mtx_unlock(&fdesc_hashmtx); 190 191 fd = malloc(sizeof(struct fdescnode), M_TEMP, M_WAITOK); 192 193 error = getnewvnode("fdescfs", mp, &fdesc_vnodeops, &vp); 194 if (error) { 195 free(fd, M_TEMP); 196 return (error); 197 } 198 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 199 vp->v_data = fd; 200 fd->fd_vnode = vp; 201 fd->fd_type = ftype; 202 fd->fd_fd = fd_fd; 203 fd->fd_ix = ix; 204 error = insmntque1(vp, mp, fdesc_insmntque_dtr, NULL); 205 if (error != 0) { 206 *vpp = NULLVP; 207 return (error); 208 } 209 210 /* Make sure that someone didn't beat us when inserting the vnode. */ 211 mtx_lock(&fdesc_hashmtx); 212 /* 213 * If a forced unmount is progressing, we need to drop it. The flags are 214 * protected by the hashmtx. 215 */ 216 fmp = (struct fdescmount *)mp->mnt_data; 217 if (fmp == NULL || fmp->flags & FMNT_UNMOUNTF) { 218 mtx_unlock(&fdesc_hashmtx); 219 vgone(vp); 220 vput(vp); 221 *vpp = NULLVP; 222 return (-1); 223 } 224 225 LIST_FOREACH(fd2, fc, fd_hash) { 226 if (fd2->fd_ix == ix && fd2->fd_vnode->v_mount == mp) { 227 /* Get reference to vnode in case it's being free'd */ 228 vp2 = fd2->fd_vnode; 229 VI_LOCK(vp2); 230 mtx_unlock(&fdesc_hashmtx); 231 error = vget(vp2, LK_EXCLUSIVE | LK_INTERLOCK, td); 232 /* Someone beat us, dec use count and wait for reclaim */ 233 vgone(vp); 234 vput(vp); 235 /* If we didn't get it, return no vnode. */ 236 if (error) 237 vp2 = NULLVP; 238 *vpp = vp2; 239 return (error); 240 } 241 } 242 243 /* If we came here, we can insert it safely. */ 244 LIST_INSERT_HEAD(fc, fd, fd_hash); 245 mtx_unlock(&fdesc_hashmtx); 246 *vpp = vp; 247 return (0); 248 } 249 250 struct fdesc_get_ino_args { 251 fdntype ftype; 252 unsigned fd_fd; 253 int ix; 254 struct file *fp; 255 struct thread *td; 256 }; 257 258 static int 259 fdesc_get_ino_alloc(struct mount *mp, void *arg, int lkflags, 260 struct vnode **rvp) 261 { 262 struct fdesc_get_ino_args *a; 263 int error; 264 265 a = arg; 266 error = fdesc_allocvp(a->ftype, a->fd_fd, a->ix, mp, rvp); 267 fdrop(a->fp, a->td); 268 return (error); 269 } 270 271 272 /* 273 * vp is the current namei directory 274 * ndp is the name to locate in that directory... 275 */ 276 static int 277 fdesc_lookup(ap) 278 struct vop_lookup_args /* { 279 struct vnode * a_dvp; 280 struct vnode ** a_vpp; 281 struct componentname * a_cnp; 282 } */ *ap; 283 { 284 struct vnode **vpp = ap->a_vpp; 285 struct vnode *dvp = ap->a_dvp; 286 struct componentname *cnp = ap->a_cnp; 287 char *pname = cnp->cn_nameptr; 288 struct thread *td = cnp->cn_thread; 289 struct file *fp; 290 struct fdesc_get_ino_args arg; 291 int nlen = cnp->cn_namelen; 292 u_int fd, fd1; 293 int error; 294 struct vnode *fvp; 295 296 if ((cnp->cn_flags & ISLASTCN) && 297 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 298 error = EROFS; 299 goto bad; 300 } 301 302 if (cnp->cn_namelen == 1 && *pname == '.') { 303 *vpp = dvp; 304 VREF(dvp); 305 return (0); 306 } 307 308 if (VTOFDESC(dvp)->fd_type != Froot) { 309 error = ENOTDIR; 310 goto bad; 311 } 312 313 fd = 0; 314 /* the only time a leading 0 is acceptable is if it's "" */ 315 if (*pname == '' && nlen != 1) { 316 error = ENOENT; 317 goto bad; 318 } 319 while (nlen--) { 320 if (*pname < '' || *pname > '9') { 321 error = ENOENT; 322 goto bad; 323 } 324 fd1 = 10 * fd + *pname++ - ''; 325 if (fd1 < fd) { 326 error = ENOENT; 327 goto bad; 328 } 329 fd = fd1; 330 } 331 332 /* 333 * No rights to check since 'fp' isn't actually used. 334 */ 335 if ((error = fget(td, fd, NULL, &fp)) != 0) 336 goto bad; 337 338 /* Check if we're looking up ourselves. */ 339 if (VTOFDESC(dvp)->fd_ix == FD_DESC + fd) { 340 /* 341 * In case we're holding the last reference to the file, the dvp 342 * will be re-acquired. 343 */ 344 vhold(dvp); 345 VOP_UNLOCK(dvp, 0); 346 fdrop(fp, td); 347 348 /* Re-aquire the lock afterwards. */ 349 vn_lock(dvp, LK_RETRY | LK_EXCLUSIVE); 350 vdrop(dvp); 351 fvp = dvp; 352 if ((dvp->v_iflag & VI_DOOMED) != 0) 353 error = ENOENT; 354 } else { 355 /* 356 * Unlock our root node (dvp) when doing this, since we might 357 * deadlock since the vnode might be locked by another thread 358 * and the root vnode lock will be obtained afterwards (in case 359 * we're looking up the fd of the root vnode), which will be the 360 * opposite lock order. Vhold the root vnode first so we don't 361 * lose it. 362 */ 363 arg.ftype = Fdesc; 364 arg.fd_fd = fd; 365 arg.ix = FD_DESC + fd; 366 arg.fp = fp; 367 arg.td = td; 368 error = vn_vget_ino_gen(dvp, fdesc_get_ino_alloc, &arg, 369 LK_EXCLUSIVE, &fvp); 370 } 371 372 if (error) 373 goto bad; 374 *vpp = fvp; 375 return (0); 376 377 bad: 378 *vpp = NULL; 379 return (error); 380 } 381 382 static int 383 fdesc_open(ap) 384 struct vop_open_args /* { 385 struct vnode *a_vp; 386 int a_mode; 387 struct ucred *a_cred; 388 struct thread *a_td; 389 } */ *ap; 390 { 391 struct vnode *vp = ap->a_vp; 392 393 if (VTOFDESC(vp)->fd_type == Froot) 394 return (0); 395 396 /* 397 * XXX Kludge: set td->td_proc->p_dupfd to contain the value of the file 398 * descriptor being sought for duplication. The error return ensures 399 * that the vnode for this device will be released by vn_open. Open 400 * will detect this special error and take the actions in dupfdopen. 401 * Other callers of vn_open or VOP_OPEN will simply report the 402 * error. 403 */ 404 ap->a_td->td_dupfd = VTOFDESC(vp)->fd_fd; /* XXX */ 405 return (ENODEV); 406 } 407 408 static int 409 fdesc_getattr(ap) 410 struct vop_getattr_args /* { 411 struct vnode *a_vp; 412 struct vattr *a_vap; 413 struct ucred *a_cred; 414 } */ *ap; 415 { 416 struct vnode *vp = ap->a_vp; 417 struct vattr *vap = ap->a_vap; 418 419 vap->va_mode = S_IRUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH; 420 vap->va_fileid = VTOFDESC(vp)->fd_ix; 421 vap->va_uid = 0; 422 vap->va_gid = 0; 423 vap->va_blocksize = DEV_BSIZE; 424 vap->va_atime.tv_sec = boottime.tv_sec; 425 vap->va_atime.tv_nsec = 0; 426 vap->va_mtime = vap->va_atime; 427 vap->va_ctime = vap->va_mtime; 428 vap->va_gen = 0; 429 vap->va_flags = 0; 430 vap->va_bytes = 0; 431 vap->va_filerev = 0; 432 433 switch (VTOFDESC(vp)->fd_type) { 434 case Froot: 435 vap->va_type = VDIR; 436 vap->va_nlink = 2; 437 vap->va_size = DEV_BSIZE; 438 vap->va_rdev = NODEV; 439 break; 440 441 case Fdesc: 442 vap->va_type = VCHR; 443 vap->va_nlink = 1; 444 vap->va_size = 0; 445 vap->va_rdev = makedev(0, vap->va_fileid); 446 break; 447 448 default: 449 panic("fdesc_getattr"); 450 break; 451 } 452 453 vp->v_type = vap->va_type; 454 return (0); 455 } 456 457 static int 458 fdesc_setattr(ap) 459 struct vop_setattr_args /* { 460 struct vnode *a_vp; 461 struct vattr *a_vap; 462 struct ucred *a_cred; 463 } */ *ap; 464 { 465 struct vattr *vap = ap->a_vap; 466 struct vnode *vp; 467 struct mount *mp; 468 struct file *fp; 469 struct thread *td = curthread; 470 cap_rights_t rights; 471 unsigned fd; 472 int error; 473 474 /* 475 * Can't mess with the root vnode 476 */ 477 if (VTOFDESC(ap->a_vp)->fd_type == Froot) 478 return (EACCES); 479 480 fd = VTOFDESC(ap->a_vp)->fd_fd; 481 482 /* 483 * Allow setattr where there is an underlying vnode. 484 */ 485 error = getvnode(td->td_proc->p_fd, fd, 486 cap_rights_init(&rights, CAP_EXTATTR_SET), &fp); 487 if (error) { 488 /* 489 * getvnode() returns EINVAL if the file descriptor is not 490 * backed by a vnode. Silently drop all changes except 491 * chflags(2) in this case. 492 */ 493 if (error == EINVAL) { 494 if (vap->va_flags != VNOVAL) 495 error = EOPNOTSUPP; 496 else 497 error = 0; 498 } 499 return (error); 500 } 501 vp = fp->f_vnode; 502 if ((error = vn_start_write(vp, &mp, V_WAIT | PCATCH)) == 0) { 503 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 504 error = VOP_SETATTR(vp, ap->a_vap, ap->a_cred); 505 VOP_UNLOCK(vp, 0); 506 vn_finished_write(mp); 507 } 508 fdrop(fp, td); 509 return (error); 510 } 511 512 #define UIO_MX 16 513 514 static int 515 fdesc_readdir(ap) 516 struct vop_readdir_args /* { 517 struct vnode *a_vp; 518 struct uio *a_uio; 519 struct ucred *a_cred; 520 int *a_eofflag; 521 u_long *a_cookies; 522 int a_ncookies; 523 } */ *ap; 524 { 525 struct uio *uio = ap->a_uio; 526 struct filedesc *fdp; 527 struct dirent d; 528 struct dirent *dp = &d; 529 int error, i, off, fcnt; 530 531 if (VTOFDESC(ap->a_vp)->fd_type != Froot) 532 panic("fdesc_readdir: not dir"); 533 534 if (ap->a_ncookies != NULL) 535 *ap->a_ncookies = 0; 536 537 off = (int)uio->uio_offset; 538 if (off != uio->uio_offset || off < 0 || (u_int)off % UIO_MX != 0 || 539 uio->uio_resid < UIO_MX) 540 return (EINVAL); 541 i = (u_int)off / UIO_MX; 542 fdp = uio->uio_td->td_proc->p_fd; 543 error = 0; 544 545 fcnt = i - 2; /* The first two nodes are `.' and `..' */ 546 547 FILEDESC_SLOCK(fdp); 548 while (i < fdp->fd_nfiles + 2 && uio->uio_resid >= UIO_MX) { 549 bzero((caddr_t)dp, UIO_MX); 550 switch (i) { 551 case 0: /* `.' */ 552 case 1: /* `..' */ 553 dp->d_fileno = i + FD_ROOT; 554 dp->d_namlen = i + 1; 555 dp->d_reclen = UIO_MX; 556 bcopy("..", dp->d_name, dp->d_namlen); 557 dp->d_name[i + 1] = '\0'; 558 dp->d_type = DT_DIR; 559 break; 560 default: 561 if (fdp->fd_ofiles[fcnt].fde_file == NULL) 562 break; 563 dp->d_namlen = sprintf(dp->d_name, "%d", fcnt); 564 dp->d_reclen = UIO_MX; 565 dp->d_type = DT_CHR; 566 dp->d_fileno = i + FD_DESC; 567 break; 568 } 569 if (dp->d_namlen != 0) { 570 /* 571 * And ship to userland 572 */ 573 FILEDESC_SUNLOCK(fdp); 574 error = uiomove(dp, UIO_MX, uio); 575 if (error) 576 goto done; 577 FILEDESC_SLOCK(fdp); 578 } 579 i++; 580 fcnt++; 581 } 582 FILEDESC_SUNLOCK(fdp); 583 584 done: 585 uio->uio_offset = i * UIO_MX; 586 return (error); 587 } 588 589 static int 590 fdesc_reclaim(ap) 591 struct vop_reclaim_args /* { 592 struct vnode *a_vp; 593 } */ *ap; 594 { 595 struct vnode *vp; 596 struct fdescnode *fd; 597 598 vp = ap->a_vp; 599 fd = VTOFDESC(vp); 600 fdesc_remove_entry(fd); 601 free(vp->v_data, M_TEMP); 602 vp->v_data = NULL; 603 return (0); 604 }
Cache object: bad4af0ea5f24eb8f707636cb9496f46
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