Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_lookup.c
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1 /* 2 * Copyright (c) 1982, 1986, 1989, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 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. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * @(#)vfs_lookup.c 8.4 (Berkeley) 2/16/94 39 * $FreeBSD$ 40 */ 41 42 #include "opt_ktrace.h" 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/namei.h> 47 #include <sys/vnode.h> 48 #include <sys/mount.h> 49 #include <sys/filedesc.h> 50 #include <sys/proc.h> 51 52 #ifdef KTRACE 53 #include <sys/ktrace.h> 54 #endif 55 56 #include <vm/vm_zone.h> 57 58 /* 59 * Convert a pathname into a pointer to a locked inode. 60 * 61 * The FOLLOW flag is set when symbolic links are to be followed 62 * when they occur at the end of the name translation process. 63 * Symbolic links are always followed for all other pathname 64 * components other than the last. 65 * 66 * The segflg defines whether the name is to be copied from user 67 * space or kernel space. 68 * 69 * Overall outline of namei: 70 * 71 * copy in name 72 * get starting directory 73 * while (!done && !error) { 74 * call lookup to search path. 75 * if symbolic link, massage name in buffer and continue 76 * } 77 */ 78 int 79 namei(ndp) 80 register struct nameidata *ndp; 81 { 82 register struct filedesc *fdp; /* pointer to file descriptor state */ 83 register char *cp; /* pointer into pathname argument */ 84 register struct vnode *dp; /* the directory we are searching */ 85 struct iovec aiov; /* uio for reading symbolic links */ 86 struct uio auio; 87 int error, linklen; 88 struct componentname *cnp = &ndp->ni_cnd; 89 struct proc *p = cnp->cn_proc; 90 91 ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_proc->p_ucred; 92 KASSERT(cnp->cn_cred && cnp->cn_proc, ("namei: bad cred/proc")); 93 KASSERT((cnp->cn_nameiop & (~OPMASK)) == 0, 94 ("namei: nameiop contaminated with flags")); 95 KASSERT((cnp->cn_flags & OPMASK) == 0, 96 ("namei: flags contaminated with nameiops")); 97 fdp = cnp->cn_proc->p_fd; 98 99 /* 100 * Get a buffer for the name to be translated, and copy the 101 * name into the buffer. 102 */ 103 if ((cnp->cn_flags & HASBUF) == 0) 104 cnp->cn_pnbuf = zalloc(namei_zone); 105 if (ndp->ni_segflg == UIO_SYSSPACE) 106 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, 107 MAXPATHLEN, (size_t *)&ndp->ni_pathlen); 108 else 109 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, 110 MAXPATHLEN, (size_t *)&ndp->ni_pathlen); 111 112 /* 113 * Don't allow empty pathnames. 114 */ 115 if (!error && *cnp->cn_pnbuf == '\0') 116 error = ENOENT; 117 118 if (error) { 119 zfree(namei_zone, cnp->cn_pnbuf); 120 ndp->ni_vp = NULL; 121 return (error); 122 } 123 ndp->ni_loopcnt = 0; 124 #ifdef KTRACE 125 if (KTRPOINT(cnp->cn_proc, KTR_NAMEI)) 126 ktrnamei(cnp->cn_proc->p_tracep, cnp->cn_pnbuf); 127 #endif 128 129 /* 130 * Get starting point for the translation. 131 */ 132 ndp->ni_rootdir = fdp->fd_rdir; 133 134 dp = fdp->fd_cdir; 135 VREF(dp); 136 for (;;) { 137 /* 138 * Check if root directory should replace current directory. 139 * Done at start of translation and after symbolic link. 140 */ 141 cnp->cn_nameptr = cnp->cn_pnbuf; 142 if (*(cnp->cn_nameptr) == '/') { 143 vrele(dp); 144 while (*(cnp->cn_nameptr) == '/') { 145 cnp->cn_nameptr++; 146 ndp->ni_pathlen--; 147 } 148 dp = ndp->ni_rootdir; 149 VREF(dp); 150 } 151 ndp->ni_startdir = dp; 152 error = lookup(ndp); 153 if (error) { 154 zfree(namei_zone, cnp->cn_pnbuf); 155 return (error); 156 } 157 /* 158 * Check for symbolic link 159 */ 160 if ((cnp->cn_flags & ISSYMLINK) == 0) { 161 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) 162 zfree(namei_zone, cnp->cn_pnbuf); 163 else 164 cnp->cn_flags |= HASBUF; 165 166 if (ndp->ni_vp && ndp->ni_vp->v_type == VREG && 167 (cnp->cn_nameiop != DELETE) && 168 ((cnp->cn_flags & (NOOBJ|LOCKLEAF)) == 169 LOCKLEAF)) 170 vfs_object_create(ndp->ni_vp, 171 ndp->ni_cnd.cn_proc, 172 ndp->ni_cnd.cn_cred); 173 174 return (0); 175 } 176 if ((cnp->cn_flags & LOCKPARENT) && ndp->ni_pathlen == 1) 177 VOP_UNLOCK(ndp->ni_dvp, 0, p); 178 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) { 179 error = ELOOP; 180 break; 181 } 182 if (ndp->ni_pathlen > 1) 183 cp = zalloc(namei_zone); 184 else 185 cp = cnp->cn_pnbuf; 186 aiov.iov_base = cp; 187 aiov.iov_len = MAXPATHLEN; 188 auio.uio_iov = &aiov; 189 auio.uio_iovcnt = 1; 190 auio.uio_offset = 0; 191 auio.uio_rw = UIO_READ; 192 auio.uio_segflg = UIO_SYSSPACE; 193 auio.uio_procp = (struct proc *)0; 194 auio.uio_resid = MAXPATHLEN; 195 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred); 196 if (error) { 197 if (ndp->ni_pathlen > 1) 198 zfree(namei_zone, cp); 199 break; 200 } 201 linklen = MAXPATHLEN - auio.uio_resid; 202 if (linklen + ndp->ni_pathlen >= MAXPATHLEN) { 203 if (ndp->ni_pathlen > 1) 204 zfree(namei_zone, cp); 205 error = ENAMETOOLONG; 206 break; 207 } 208 if (ndp->ni_pathlen > 1) { 209 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen); 210 zfree(namei_zone, cnp->cn_pnbuf); 211 cnp->cn_pnbuf = cp; 212 } else 213 cnp->cn_pnbuf[linklen] = '\0'; 214 ndp->ni_pathlen += linklen; 215 vput(ndp->ni_vp); 216 dp = ndp->ni_dvp; 217 } 218 zfree(namei_zone, cnp->cn_pnbuf); 219 vrele(ndp->ni_dvp); 220 vput(ndp->ni_vp); 221 ndp->ni_vp = NULL; 222 return (error); 223 } 224 225 /* 226 * Search a pathname. 227 * This is a very central and rather complicated routine. 228 * 229 * The pathname is pointed to by ni_ptr and is of length ni_pathlen. 230 * The starting directory is taken from ni_startdir. The pathname is 231 * descended until done, or a symbolic link is encountered. The variable 232 * ni_more is clear if the path is completed; it is set to one if a 233 * symbolic link needing interpretation is encountered. 234 * 235 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 236 * whether the name is to be looked up, created, renamed, or deleted. 237 * When CREATE, RENAME, or DELETE is specified, information usable in 238 * creating, renaming, or deleting a directory entry may be calculated. 239 * If flag has LOCKPARENT or'ed into it, the parent directory is returned 240 * locked. If flag has WANTPARENT or'ed into it, the parent directory is 241 * returned unlocked. Otherwise the parent directory is not returned. If 242 * the target of the pathname exists and LOCKLEAF is or'ed into the flag 243 * the target is returned locked, otherwise it is returned unlocked. 244 * When creating or renaming and LOCKPARENT is specified, the target may not 245 * be ".". When deleting and LOCKPARENT is specified, the target may be ".". 246 * 247 * Overall outline of lookup: 248 * 249 * dirloop: 250 * identify next component of name at ndp->ni_ptr 251 * handle degenerate case where name is null string 252 * if .. and crossing mount points and on mounted filesys, find parent 253 * call VOP_LOOKUP routine for next component name 254 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set 255 * component vnode returned in ni_vp (if it exists), locked. 256 * if result vnode is mounted on and crossing mount points, 257 * find mounted on vnode 258 * if more components of name, do next level at dirloop 259 * return the answer in ni_vp, locked if LOCKLEAF set 260 * if LOCKPARENT set, return locked parent in ni_dvp 261 * if WANTPARENT set, return unlocked parent in ni_dvp 262 */ 263 int 264 lookup(ndp) 265 register struct nameidata *ndp; 266 { 267 register char *cp; /* pointer into pathname argument */ 268 register struct vnode *dp = 0; /* the directory we are searching */ 269 struct vnode *tdp; /* saved dp */ 270 struct mount *mp; /* mount table entry */ 271 int docache; /* == 0 do not cache last component */ 272 int wantparent; /* 1 => wantparent or lockparent flag */ 273 int rdonly; /* lookup read-only flag bit */ 274 int trailing_slash; 275 int error = 0; 276 struct componentname *cnp = &ndp->ni_cnd; 277 struct proc *p = cnp->cn_proc; 278 279 /* 280 * Setup: break out flag bits into variables. 281 */ 282 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT); 283 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 284 if (cnp->cn_nameiop == DELETE || 285 (wantparent && cnp->cn_nameiop != CREATE && 286 cnp->cn_nameiop != LOOKUP)) 287 docache = 0; 288 rdonly = cnp->cn_flags & RDONLY; 289 ndp->ni_dvp = NULL; 290 cnp->cn_flags &= ~ISSYMLINK; 291 dp = ndp->ni_startdir; 292 ndp->ni_startdir = NULLVP; 293 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY, p); 294 295 dirloop: 296 /* 297 * Search a new directory. 298 * 299 * The cn_hash value is for use by vfs_cache. 300 * The last component of the filename is left accessible via 301 * cnp->cn_nameptr for callers that need the name. Callers needing 302 * the name set the SAVENAME flag. When done, they assume 303 * responsibility for freeing the pathname buffer. 304 */ 305 cnp->cn_consume = 0; 306 cnp->cn_hash = 0; 307 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++) 308 cnp->cn_hash += (unsigned char)*cp; 309 cnp->cn_namelen = cp - cnp->cn_nameptr; 310 if (cnp->cn_namelen > NAME_MAX) { 311 error = ENAMETOOLONG; 312 goto bad; 313 } 314 #ifdef NAMEI_DIAGNOSTIC 315 { char c = *cp; 316 *cp = '\0'; 317 printf("{%s}: ", cnp->cn_nameptr); 318 *cp = c; } 319 #endif 320 ndp->ni_pathlen -= cnp->cn_namelen; 321 ndp->ni_next = cp; 322 323 /* 324 * Replace multiple slashes by a single slash and trailing slashes 325 * by a null. This must be done before VOP_LOOKUP() because some 326 * fs's don't know about trailing slashes. Remember if there were 327 * trailing slashes to handle symlinks, existing non-directories 328 * and non-existing files that won't be directories specially later. 329 */ 330 trailing_slash = 0; 331 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) { 332 cp++; 333 ndp->ni_pathlen--; 334 if (*cp == '\0') { 335 trailing_slash = 1; 336 *ndp->ni_next = '\0'; /* XXX for direnter() ... */ 337 } 338 } 339 ndp->ni_next = cp; 340 341 cnp->cn_flags |= MAKEENTRY; 342 if (*cp == '\0' && docache == 0) 343 cnp->cn_flags &= ~MAKEENTRY; 344 if (cnp->cn_namelen == 2 && 345 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') 346 cnp->cn_flags |= ISDOTDOT; 347 else 348 cnp->cn_flags &= ~ISDOTDOT; 349 if (*ndp->ni_next == 0) 350 cnp->cn_flags |= ISLASTCN; 351 else 352 cnp->cn_flags &= ~ISLASTCN; 353 354 355 /* 356 * Check for degenerate name (e.g. / or "") 357 * which is a way of talking about a directory, 358 * e.g. like "/." or ".". 359 */ 360 if (cnp->cn_nameptr[0] == '\0') { 361 if (dp->v_type != VDIR) { 362 error = ENOTDIR; 363 goto bad; 364 } 365 if (cnp->cn_nameiop != LOOKUP) { 366 error = EISDIR; 367 goto bad; 368 } 369 if (wantparent) { 370 ndp->ni_dvp = dp; 371 VREF(dp); 372 } 373 ndp->ni_vp = dp; 374 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF))) 375 VOP_UNLOCK(dp, 0, p); 376 if (cnp->cn_flags & SAVESTART) 377 panic("lookup: SAVESTART"); 378 return (0); 379 } 380 381 /* 382 * Handle "..": two special cases. 383 * 1. If at root directory (e.g. after chroot) 384 * or at absolute root directory 385 * then ignore it so can't get out. 386 * 2. If this vnode is the root of a mounted 387 * filesystem, then replace it with the 388 * vnode which was mounted on so we take the 389 * .. in the other file system. 390 */ 391 if (cnp->cn_flags & ISDOTDOT) { 392 for (;;) { 393 if (dp == ndp->ni_rootdir || dp == rootvnode) { 394 ndp->ni_dvp = dp; 395 ndp->ni_vp = dp; 396 VREF(dp); 397 goto nextname; 398 } 399 if ((dp->v_flag & VROOT) == 0 || 400 (cnp->cn_flags & NOCROSSMOUNT)) 401 break; 402 tdp = dp; 403 dp = dp->v_mount->mnt_vnodecovered; 404 vput(tdp); 405 VREF(dp); 406 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY, p); 407 } 408 } 409 410 /* 411 * We now have a segment name to search for, and a directory to search. 412 */ 413 unionlookup: 414 ndp->ni_dvp = dp; 415 ndp->ni_vp = NULL; 416 ASSERT_VOP_LOCKED(dp, "lookup"); 417 if (error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) { 418 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty")); 419 #ifdef NAMEI_DIAGNOSTIC 420 printf("not found\n"); 421 #endif 422 if ((error == ENOENT) && 423 (dp->v_flag & VROOT) && 424 (dp->v_mount->mnt_flag & MNT_UNION)) { 425 tdp = dp; 426 dp = dp->v_mount->mnt_vnodecovered; 427 vput(tdp); 428 VREF(dp); 429 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY, p); 430 goto unionlookup; 431 } 432 433 if (error != EJUSTRETURN) 434 goto bad; 435 /* 436 * If creating and at end of pathname, then can consider 437 * allowing file to be created. 438 */ 439 if (rdonly) { 440 error = EROFS; 441 goto bad; 442 } 443 if (*cp == '\0' && trailing_slash && 444 !(cnp->cn_flags & WILLBEDIR)) { 445 error = ENOENT; 446 goto bad; 447 } 448 /* 449 * We return with ni_vp NULL to indicate that the entry 450 * doesn't currently exist, leaving a pointer to the 451 * (possibly locked) directory inode in ndp->ni_dvp. 452 */ 453 if (cnp->cn_flags & SAVESTART) { 454 ndp->ni_startdir = ndp->ni_dvp; 455 VREF(ndp->ni_startdir); 456 } 457 return (0); 458 } 459 #ifdef NAMEI_DIAGNOSTIC 460 printf("found\n"); 461 #endif 462 463 ASSERT_VOP_LOCKED(ndp->ni_vp, "lookup"); 464 465 /* 466 * Take into account any additional components consumed by 467 * the underlying filesystem. 468 */ 469 if (cnp->cn_consume > 0) { 470 cnp->cn_nameptr += cnp->cn_consume; 471 ndp->ni_next += cnp->cn_consume; 472 ndp->ni_pathlen -= cnp->cn_consume; 473 cnp->cn_consume = 0; 474 } 475 476 dp = ndp->ni_vp; 477 478 /* 479 * Check to see if the vnode has been mounted on; 480 * if so find the root of the mounted file system. 481 */ 482 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) && 483 (cnp->cn_flags & NOCROSSMOUNT) == 0) { 484 if (vfs_busy(mp, 0, 0, p)) 485 continue; 486 error = VFS_ROOT(mp, &tdp); 487 vfs_unbusy(mp, p); 488 if (error) 489 goto bad2; 490 vput(dp); 491 ndp->ni_vp = dp = tdp; 492 } 493 494 /* 495 * Check for symbolic link 496 */ 497 if ((dp->v_type == VLNK) && 498 ((cnp->cn_flags & FOLLOW) || trailing_slash || 499 *ndp->ni_next == '/')) { 500 cnp->cn_flags |= ISSYMLINK; 501 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) { 502 error = EACCES; 503 goto bad2; 504 } 505 return (0); 506 } 507 508 /* 509 * Check for bogus trailing slashes. 510 */ 511 if (trailing_slash && dp->v_type != VDIR) { 512 error = ENOTDIR; 513 goto bad2; 514 } 515 516 nextname: 517 /* 518 * Not a symbolic link. If more pathname, 519 * continue at next component, else return. 520 */ 521 if (*ndp->ni_next == '/') { 522 cnp->cn_nameptr = ndp->ni_next; 523 while (*cnp->cn_nameptr == '/') { 524 cnp->cn_nameptr++; 525 ndp->ni_pathlen--; 526 } 527 if (ndp->ni_dvp != ndp->ni_vp) { 528 ASSERT_VOP_UNLOCKED(ndp->ni_dvp, "lookup"); 529 } 530 vrele(ndp->ni_dvp); 531 goto dirloop; 532 } 533 /* 534 * Disallow directory write attempts on read-only file systems. 535 */ 536 if (rdonly && 537 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 538 error = EROFS; 539 goto bad2; 540 } 541 if (cnp->cn_flags & SAVESTART) { 542 ndp->ni_startdir = ndp->ni_dvp; 543 VREF(ndp->ni_startdir); 544 } 545 if (!wantparent) 546 vrele(ndp->ni_dvp); 547 548 if ((cnp->cn_flags & LOCKLEAF) == 0) 549 VOP_UNLOCK(dp, 0, p); 550 return (0); 551 552 bad2: 553 if ((cnp->cn_flags & LOCKPARENT) && *ndp->ni_next == '\0') 554 VOP_UNLOCK(ndp->ni_dvp, 0, p); 555 vrele(ndp->ni_dvp); 556 bad: 557 vput(dp); 558 ndp->ni_vp = NULL; 559 return (error); 560 } 561 562 /* 563 * relookup - lookup a path name component 564 * Used by lookup to re-aquire things. 565 */ 566 int 567 relookup(dvp, vpp, cnp) 568 struct vnode *dvp, **vpp; 569 struct componentname *cnp; 570 { 571 struct proc *p = cnp->cn_proc; 572 struct vnode *dp = 0; /* the directory we are searching */ 573 int docache; /* == 0 do not cache last component */ 574 int wantparent; /* 1 => wantparent or lockparent flag */ 575 int rdonly; /* lookup read-only flag bit */ 576 int error = 0; 577 #ifdef NAMEI_DIAGNOSTIC 578 int newhash; /* DEBUG: check name hash */ 579 char *cp; /* DEBUG: check name ptr/len */ 580 #endif 581 582 /* 583 * Setup: break out flag bits into variables. 584 */ 585 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT); 586 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 587 if (cnp->cn_nameiop == DELETE || 588 (wantparent && cnp->cn_nameiop != CREATE)) 589 docache = 0; 590 rdonly = cnp->cn_flags & RDONLY; 591 cnp->cn_flags &= ~ISSYMLINK; 592 dp = dvp; 593 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY, p); 594 595 /* dirloop: */ 596 /* 597 * Search a new directory. 598 * 599 * The cn_hash value is for use by vfs_cache. 600 * The last component of the filename is left accessible via 601 * cnp->cn_nameptr for callers that need the name. Callers needing 602 * the name set the SAVENAME flag. When done, they assume 603 * responsibility for freeing the pathname buffer. 604 */ 605 #ifdef NAMEI_DIAGNOSTIC 606 for (newhash = 0, cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++) 607 newhash += (unsigned char)*cp; 608 if (newhash != cnp->cn_hash) 609 panic("relookup: bad hash"); 610 if (cnp->cn_namelen != cp - cnp->cn_nameptr) 611 panic ("relookup: bad len"); 612 if (*cp != 0) 613 panic("relookup: not last component"); 614 printf("{%s}: ", cnp->cn_nameptr); 615 #endif 616 617 /* 618 * Check for degenerate name (e.g. / or "") 619 * which is a way of talking about a directory, 620 * e.g. like "/." or ".". 621 */ 622 if (cnp->cn_nameptr[0] == '\0') { 623 if (cnp->cn_nameiop != LOOKUP || wantparent) { 624 error = EISDIR; 625 goto bad; 626 } 627 if (dp->v_type != VDIR) { 628 error = ENOTDIR; 629 goto bad; 630 } 631 if (!(cnp->cn_flags & LOCKLEAF)) 632 VOP_UNLOCK(dp, 0, p); 633 *vpp = dp; 634 if (cnp->cn_flags & SAVESTART) 635 panic("lookup: SAVESTART"); 636 return (0); 637 } 638 639 if (cnp->cn_flags & ISDOTDOT) 640 panic ("relookup: lookup on dot-dot"); 641 642 /* 643 * We now have a segment name to search for, and a directory to search. 644 */ 645 if (error = VOP_LOOKUP(dp, vpp, cnp)) { 646 KASSERT(*vpp == NULL, ("leaf should be empty")); 647 if (error != EJUSTRETURN) 648 goto bad; 649 /* 650 * If creating and at end of pathname, then can consider 651 * allowing file to be created. 652 */ 653 if (rdonly) { 654 error = EROFS; 655 goto bad; 656 } 657 /* ASSERT(dvp == ndp->ni_startdir) */ 658 if (cnp->cn_flags & SAVESTART) 659 VREF(dvp); 660 /* 661 * We return with ni_vp NULL to indicate that the entry 662 * doesn't currently exist, leaving a pointer to the 663 * (possibly locked) directory inode in ndp->ni_dvp. 664 */ 665 return (0); 666 } 667 dp = *vpp; 668 669 /* 670 * Check for symbolic link 671 */ 672 KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW), 673 ("relookup: symlink found.\n")); 674 675 /* 676 * Disallow directory write attempts on read-only file systems. 677 */ 678 if (rdonly && 679 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 680 error = EROFS; 681 goto bad2; 682 } 683 /* ASSERT(dvp == ndp->ni_startdir) */ 684 if (cnp->cn_flags & SAVESTART) 685 VREF(dvp); 686 687 if (!wantparent) 688 vrele(dvp); 689 690 if (dp->v_type == VREG && 691 ((cnp->cn_flags & (NOOBJ|LOCKLEAF)) == LOCKLEAF)) 692 vfs_object_create(dp, cnp->cn_proc, cnp->cn_cred); 693 694 if ((cnp->cn_flags & LOCKLEAF) == 0) 695 VOP_UNLOCK(dp, 0, p); 696 return (0); 697 698 bad2: 699 if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN)) 700 VOP_UNLOCK(dvp, 0, p); 701 vrele(dvp); 702 bad: 703 vput(dp); 704 *vpp = NULL; 705 return (error); 706 }
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