1 /* $NetBSD: vfs_lookup.c,v 1.23 1997/05/08 14:55:22 mycroft Exp $ */ 2 3 /* 4 * Copyright (c) 1982, 1986, 1989, 1993 5 * The Regents of the University of California. All rights reserved. 6 * (c) UNIX System Laboratories, Inc. 7 * All or some portions of this file are derived from material licensed 8 * to the University of California by American Telephone and Telegraph 9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 10 * the permission of UNIX System Laboratories, Inc. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the University of 23 * California, Berkeley and its contributors. 24 * 4. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 * 40 * @(#)vfs_lookup.c 8.6 (Berkeley) 11/21/94 41 */ 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/syslimits.h> 46 #include <sys/time.h> 47 #include <sys/namei.h> 48 #include <sys/vnode.h> 49 #include <sys/mount.h> 50 #include <sys/errno.h> 51 #include <sys/malloc.h> 52 #include <sys/filedesc.h> 53 #include <sys/proc.h> 54 55 #ifdef KTRACE 56 #include <sys/ktrace.h> 57 #endif 58 59 /* 60 * Convert a pathname into a pointer to a locked inode. 61 * 62 * The FOLLOW flag is set when symbolic links are to be followed 63 * when they occur at the end of the name translation process. 64 * Symbolic links are always followed for all other pathname 65 * components other than the last. 66 * 67 * The segflg defines whether the name is to be copied from user 68 * space or kernel space. 69 * 70 * Overall outline of namei: 71 * 72 * copy in name 73 * get starting directory 74 * while (!done && !error) { 75 * call lookup to search path. 76 * if symbolic link, massage name in buffer and continue 77 * } 78 */ 79 int 80 namei(ndp) 81 register struct nameidata *ndp; 82 { 83 register struct filedesc *fdp; /* pointer to file descriptor state */ 84 register char *cp; /* pointer into pathname argument */ 85 register struct vnode *dp; /* the directory we are searching */ 86 struct iovec aiov; /* uio for reading symbolic links */ 87 struct uio auio; 88 int error, linklen; 89 struct componentname *cnp = &ndp->ni_cnd; 90 91 ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_proc->p_ucred; 92 #ifdef DIAGNOSTIC 93 if (!cnp->cn_cred || !cnp->cn_proc) 94 panic ("namei: bad cred/proc"); 95 if (cnp->cn_nameiop & (~OPMASK)) 96 panic ("namei: nameiop contaminated with flags"); 97 if (cnp->cn_flags & OPMASK) 98 panic ("namei: flags contaminated with nameiops"); 99 #endif 100 fdp = cnp->cn_proc->p_fd; 101 102 /* 103 * Get a buffer for the name to be translated, and copy the 104 * name into the buffer. 105 */ 106 if ((cnp->cn_flags & HASBUF) == 0) 107 MALLOC(cnp->cn_pnbuf, caddr_t, MAXPATHLEN, M_NAMEI, M_WAITOK); 108 if (ndp->ni_segflg == UIO_SYSSPACE) 109 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, 110 MAXPATHLEN, &ndp->ni_pathlen); 111 else 112 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, 113 MAXPATHLEN, &ndp->ni_pathlen); 114 115 /* 116 * POSIX.1 requirement: "" is not a valid file name. 117 */ 118 if (!error && ndp->ni_pathlen == 1) 119 error = ENOENT; 120 121 if (error) { 122 free(cnp->cn_pnbuf, M_NAMEI); 123 ndp->ni_vp = NULL; 124 return (error); 125 } 126 ndp->ni_loopcnt = 0; 127 128 #ifdef KTRACE 129 if (KTRPOINT(cnp->cn_proc, KTR_NAMEI)) 130 ktrnamei(cnp->cn_proc->p_tracep, cnp->cn_pnbuf); 131 #endif 132 133 /* 134 * Get starting point for the translation. 135 */ 136 if ((ndp->ni_rootdir = fdp->fd_rdir) == NULL) 137 ndp->ni_rootdir = rootvnode; 138 /* 139 * Check if starting from root directory or current directory. 140 */ 141 if (cnp->cn_pnbuf[0] == '/') { 142 dp = ndp->ni_rootdir; 143 VREF(dp); 144 } else { 145 dp = fdp->fd_cdir; 146 VREF(dp); 147 } 148 for (;;) { 149 cnp->cn_nameptr = cnp->cn_pnbuf; 150 ndp->ni_startdir = dp; 151 if ((error = lookup(ndp)) != 0) { 152 FREE(cnp->cn_pnbuf, M_NAMEI); 153 return (error); 154 } 155 /* 156 * Check for symbolic link 157 */ 158 if ((cnp->cn_flags & ISSYMLINK) == 0) { 159 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) 160 FREE(cnp->cn_pnbuf, M_NAMEI); 161 else 162 cnp->cn_flags |= HASBUF; 163 return (0); 164 } 165 if ((cnp->cn_flags & LOCKPARENT) && ndp->ni_pathlen == 1) 166 VOP_UNLOCK(ndp->ni_dvp); 167 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) { 168 error = ELOOP; 169 break; 170 } 171 if (ndp->ni_pathlen > 1) 172 MALLOC(cp, char *, MAXPATHLEN, M_NAMEI, M_WAITOK); 173 else 174 cp = cnp->cn_pnbuf; 175 aiov.iov_base = cp; 176 aiov.iov_len = MAXPATHLEN; 177 auio.uio_iov = &aiov; 178 auio.uio_iovcnt = 1; 179 auio.uio_offset = 0; 180 auio.uio_rw = UIO_READ; 181 auio.uio_segflg = UIO_SYSSPACE; 182 auio.uio_procp = (struct proc *)0; 183 auio.uio_resid = MAXPATHLEN; 184 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred); 185 if (error) { 186 badlink: 187 if (ndp->ni_pathlen > 1) 188 FREE(cp, M_NAMEI); 189 break; 190 } 191 linklen = MAXPATHLEN - auio.uio_resid; 192 if (linklen == 0) { 193 error = ENOENT; 194 goto badlink; 195 } 196 if (linklen + ndp->ni_pathlen >= MAXPATHLEN) { 197 error = ENAMETOOLONG; 198 goto badlink; 199 } 200 if (ndp->ni_pathlen > 1) { 201 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen); 202 FREE(cnp->cn_pnbuf, M_NAMEI); 203 cnp->cn_pnbuf = cp; 204 } else 205 cnp->cn_pnbuf[linklen] = '\0'; 206 ndp->ni_pathlen += linklen; 207 vput(ndp->ni_vp); 208 dp = ndp->ni_dvp; 209 /* 210 * Check if root directory should replace current directory. 211 */ 212 if (cnp->cn_pnbuf[0] == '/') { 213 vrele(dp); 214 dp = ndp->ni_rootdir; 215 VREF(dp); 216 } 217 } 218 FREE(cnp->cn_pnbuf, M_NAMEI); 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 const 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 error = 0; 275 int slashes; 276 struct componentname *cnp = &ndp->ni_cnd; 277 278 /* 279 * Setup: break out flag bits into variables. 280 */ 281 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT); 282 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 283 if (cnp->cn_nameiop == DELETE || 284 (wantparent && cnp->cn_nameiop != CREATE)) 285 docache = 0; 286 rdonly = cnp->cn_flags & RDONLY; 287 ndp->ni_dvp = NULL; 288 cnp->cn_flags &= ~ISSYMLINK; 289 dp = ndp->ni_startdir; 290 ndp->ni_startdir = NULLVP; 291 VOP_LOCK(dp); 292 293 /* 294 * If we have a leading string of slashes, remove them, and just make 295 * sure the current node is a directory. 296 */ 297 cp = cnp->cn_nameptr; 298 if (*cp == '/') { 299 do { 300 cp++; 301 } while (*cp == '/'); 302 ndp->ni_pathlen -= cp - cnp->cn_nameptr; 303 cnp->cn_nameptr = cp; 304 305 if (dp->v_type != VDIR) { 306 error = ENOTDIR; 307 goto bad; 308 } 309 310 /* 311 * If we've exhausted the path name, then just return the 312 * current node. If the caller requested the parent node (i.e. 313 * it's a CREATE, DELETE, or RENAME), and we don't have one 314 * (because this is the root directory), then we must fail. 315 */ 316 if (cnp->cn_nameptr[0] == '\0') { 317 if (ndp->ni_dvp == NULL && wantparent) { 318 error = EISDIR; 319 goto bad; 320 } 321 ndp->ni_vp = dp; 322 cnp->cn_flags |= ISLASTCN; 323 goto terminal; 324 } 325 } 326 327 dirloop: 328 /* 329 * Search a new directory. 330 * 331 * The cn_hash value is for use by vfs_cache. 332 * The last component of the filename is left accessible via 333 * cnp->cn_nameptr for callers that need the name. Callers needing 334 * the name set the SAVENAME flag. When done, they assume 335 * responsibility for freeing the pathname buffer. 336 */ 337 cnp->cn_consume = 0; 338 cnp->cn_hash = 0; 339 for (cp = cnp->cn_nameptr; *cp != '\0' && *cp != '/'; cp++) 340 cnp->cn_hash += (unsigned char)*cp; 341 cnp->cn_namelen = cp - cnp->cn_nameptr; 342 if (cnp->cn_namelen > NAME_MAX) { 343 error = ENAMETOOLONG; 344 goto bad; 345 } 346 #ifdef NAMEI_DIAGNOSTIC 347 { char c = *cp; 348 *cp = '\0'; 349 printf("{%s}: ", cnp->cn_nameptr); 350 *cp = c; } 351 #endif 352 ndp->ni_pathlen -= cnp->cn_namelen; 353 ndp->ni_next = cp; 354 /* 355 * If this component is followed by a slash, then move the pointer to 356 * the next component forward, and remember that this component must be 357 * a directory. 358 */ 359 if (*cp == '/') { 360 do { 361 cp++; 362 } while (*cp == '/'); 363 slashes = cp - ndp->ni_next; 364 ndp->ni_pathlen -= slashes; 365 ndp->ni_next = cp; 366 cnp->cn_flags |= REQUIREDIR; 367 } else { 368 slashes = 0; 369 cnp->cn_flags &= ~REQUIREDIR; 370 } 371 /* 372 * We do special processing on the last component, whether or not it's 373 * a directory. Cache all intervening lookups, but not the final one. 374 */ 375 if (*cp == '\0') { 376 if (docache) 377 cnp->cn_flags |= MAKEENTRY; 378 else 379 cnp->cn_flags &= ~MAKEENTRY; 380 cnp->cn_flags |= ISLASTCN; 381 } else { 382 cnp->cn_flags |= MAKEENTRY; 383 cnp->cn_flags &= ~ISLASTCN; 384 } 385 if (cnp->cn_namelen == 2 && 386 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') 387 cnp->cn_flags |= ISDOTDOT; 388 else 389 cnp->cn_flags &= ~ISDOTDOT; 390 391 /* 392 * Handle "..": two special cases. 393 * 1. If at root directory (e.g. after chroot) 394 * or at absolute root directory 395 * then ignore it so can't get out. 396 * 2. If this vnode is the root of a mounted 397 * filesystem, then replace it with the 398 * vnode which was mounted on so we take the 399 * .. in the other file system. 400 */ 401 if (cnp->cn_flags & ISDOTDOT) { 402 for (;;) { 403 if (dp == ndp->ni_rootdir || dp == rootvnode) { 404 ndp->ni_dvp = dp; 405 ndp->ni_vp = dp; 406 VREF(dp); 407 goto nextname; 408 } 409 if ((dp->v_flag & VROOT) == 0 || 410 (cnp->cn_flags & NOCROSSMOUNT)) 411 break; 412 tdp = dp; 413 dp = dp->v_mount->mnt_vnodecovered; 414 vput(tdp); 415 VREF(dp); 416 VOP_LOCK(dp); 417 } 418 } 419 420 /* 421 * We now have a segment name to search for, and a directory to search. 422 */ 423 unionlookup: 424 ndp->ni_dvp = dp; 425 if ((error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) != 0) { 426 #ifdef DIAGNOSTIC 427 if (ndp->ni_vp != NULL) 428 panic("leaf should be empty"); 429 #endif 430 #ifdef NAMEI_DIAGNOSTIC 431 printf("not found\n"); 432 #endif 433 if ((error == ENOENT) && 434 (dp->v_flag & VROOT) && 435 (dp->v_mount->mnt_flag & MNT_UNION)) { 436 tdp = dp; 437 dp = dp->v_mount->mnt_vnodecovered; 438 vput(tdp); 439 VREF(dp); 440 VOP_LOCK(dp); 441 goto unionlookup; 442 } 443 444 if (error != EJUSTRETURN) 445 goto bad; 446 /* 447 * If this was not the last component, or there were trailing 448 * slashes, then the name must exist. 449 */ 450 if (cnp->cn_flags & REQUIREDIR) { 451 error = ENOENT; 452 goto bad; 453 } 454 /* 455 * If creating and at end of pathname, then can consider 456 * allowing file to be created. 457 */ 458 if (rdonly || (ndp->ni_dvp->v_mount->mnt_flag & MNT_RDONLY)) { 459 error = EROFS; 460 goto bad; 461 } 462 /* 463 * We return with ni_vp NULL to indicate that the entry 464 * doesn't currently exist, leaving a pointer to the 465 * (possibly locked) directory inode in ndp->ni_dvp. 466 */ 467 if (cnp->cn_flags & SAVESTART) { 468 ndp->ni_startdir = ndp->ni_dvp; 469 VREF(ndp->ni_startdir); 470 } 471 return (0); 472 } 473 #ifdef NAMEI_DIAGNOSTIC 474 printf("found\n"); 475 #endif 476 477 /* 478 * Take into account any additional components consumed by the 479 * underlying filesystem. This will include any trailing slashes after 480 * the last component consumed. 481 */ 482 if (cnp->cn_consume > 0) { 483 ndp->ni_pathlen -= cnp->cn_consume - slashes; 484 ndp->ni_next += cnp->cn_consume - slashes; 485 cnp->cn_consume = 0; 486 if (ndp->ni_next[0] == '\0') 487 cnp->cn_flags |= ISLASTCN; 488 } 489 490 dp = ndp->ni_vp; 491 /* 492 * Check to see if the vnode has been mounted on; 493 * if so find the root of the mounted file system. 494 */ 495 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) && 496 (cnp->cn_flags & NOCROSSMOUNT) == 0) { 497 if (mp->mnt_flag & MNT_MLOCK) { 498 mp->mnt_flag |= MNT_MWAIT; 499 sleep((caddr_t)mp, PVFS); 500 continue; 501 } 502 if ((error = VFS_ROOT(dp->v_mountedhere, &tdp)) != 0) 503 goto bad2; 504 vput(dp); 505 ndp->ni_vp = dp = tdp; 506 } 507 508 /* 509 * Check for symbolic link. Back up over any slashes that we skipped, 510 * as we will need them again. 511 */ 512 if ((dp->v_type == VLNK) && (cnp->cn_flags & (FOLLOW|REQUIREDIR))) { 513 ndp->ni_pathlen += slashes; 514 ndp->ni_next -= slashes; 515 cnp->cn_flags |= ISSYMLINK; 516 return (0); 517 } 518 519 /* 520 * Check for directory, if the component was followed by a series of 521 * slashes. 522 */ 523 if ((dp->v_type != VDIR) && (cnp->cn_flags & REQUIREDIR)) { 524 error = ENOTDIR; 525 goto bad2; 526 } 527 528 nextname: 529 /* 530 * Not a symbolic link. If this was not the last component, then 531 * continue at the next component, else return. 532 */ 533 if (!(cnp->cn_flags & ISLASTCN)) { 534 cnp->cn_nameptr = ndp->ni_next; 535 vrele(ndp->ni_dvp); 536 goto dirloop; 537 } 538 539 terminal: 540 /* 541 * Check for read-only file systems. 542 */ 543 if (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME) { 544 /* 545 * Disallow directory write attempts on read-only 546 * file systems. 547 */ 548 if (rdonly || (dp->v_mount->mnt_flag & MNT_RDONLY) || 549 (wantparent && 550 (ndp->ni_dvp->v_mount->mnt_flag & MNT_RDONLY))) { 551 error = EROFS; 552 goto bad2; 553 } 554 } 555 if (ndp->ni_dvp != NULL) { 556 if (cnp->cn_flags & SAVESTART) { 557 ndp->ni_startdir = ndp->ni_dvp; 558 VREF(ndp->ni_startdir); 559 } 560 if (!wantparent) 561 vrele(ndp->ni_dvp); 562 } 563 if ((cnp->cn_flags & LOCKLEAF) == 0) 564 VOP_UNLOCK(dp); 565 return (0); 566 567 bad2: 568 if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN)) 569 VOP_UNLOCK(ndp->ni_dvp); 570 vrele(ndp->ni_dvp); 571 bad: 572 vput(dp); 573 ndp->ni_vp = NULL; 574 return (error); 575 } 576 577 /* 578 * Reacquire a path name component. 579 */ 580 int 581 relookup(dvp, vpp, cnp) 582 struct vnode *dvp, **vpp; 583 struct componentname *cnp; 584 { 585 register struct vnode *dp = 0; /* the directory we are searching */ 586 int docache; /* == 0 do not cache last component */ 587 int wantparent; /* 1 => wantparent or lockparent flag */ 588 int rdonly; /* lookup read-only flag bit */ 589 int error = 0; 590 #ifdef NAMEI_DIAGNOSTIC 591 int newhash; /* DEBUG: check name hash */ 592 char *cp; /* DEBUG: check name ptr/len */ 593 #endif 594 595 /* 596 * Setup: break out flag bits into variables. 597 */ 598 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT); 599 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 600 if (cnp->cn_nameiop == DELETE || 601 (wantparent && cnp->cn_nameiop != CREATE)) 602 docache = 0; 603 rdonly = cnp->cn_flags & RDONLY; 604 cnp->cn_flags &= ~ISSYMLINK; 605 dp = dvp; 606 VOP_LOCK(dp); 607 608 /* dirloop: */ 609 /* 610 * Search a new directory. 611 * 612 * The cn_hash value is for use by vfs_cache. 613 * The last component of the filename is left accessible via 614 * cnp->cn_nameptr for callers that need the name. Callers needing 615 * the name set the SAVENAME flag. When done, they assume 616 * responsibility for freeing the pathname buffer. 617 */ 618 #ifdef NAMEI_DIAGNOSTIC 619 for (newhash = 0, cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++) 620 newhash += (unsigned char)*cp; 621 if (newhash != cnp->cn_hash) 622 panic("relookup: bad hash"); 623 if (cnp->cn_namelen != cp - cnp->cn_nameptr) 624 panic ("relookup: bad len"); 625 if (*cp != 0) 626 panic("relookup: not last component"); 627 printf("{%s}: ", cnp->cn_nameptr); 628 #endif 629 630 /* 631 * Check for degenerate name (e.g. / or "") 632 * which is a way of talking about a directory, 633 * e.g. like "/." or ".". 634 */ 635 if (cnp->cn_nameptr[0] == '\0') 636 panic("relookup: null name"); 637 638 if (cnp->cn_flags & ISDOTDOT) 639 panic ("relookup: lookup on dot-dot"); 640 641 /* 642 * We now have a segment name to search for, and a directory to search. 643 */ 644 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) { 645 #ifdef DIAGNOSTIC 646 if (*vpp != NULL) 647 panic("leaf should be empty"); 648 #endif 649 if (error != EJUSTRETURN) 650 goto bad; 651 /* 652 * If creating and at end of pathname, then can consider 653 * allowing file to be created. 654 */ 655 if (rdonly || (dvp->v_mount->mnt_flag & MNT_RDONLY)) { 656 error = EROFS; 657 goto bad; 658 } 659 /* ASSERT(dvp == ndp->ni_startdir) */ 660 if (cnp->cn_flags & SAVESTART) 661 VREF(dvp); 662 /* 663 * We return with ni_vp NULL to indicate that the entry 664 * doesn't currently exist, leaving a pointer to the 665 * (possibly locked) directory inode in ndp->ni_dvp. 666 */ 667 return (0); 668 } 669 dp = *vpp; 670 671 #ifdef DIAGNOSTIC 672 /* 673 * Check for symbolic link 674 */ 675 if (dp->v_type == VLNK && (cnp->cn_flags & FOLLOW)) 676 panic ("relookup: symlink found.\n"); 677 #endif 678 679 /* 680 * Check for read-only file systems. 681 */ 682 if (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME) { 683 /* 684 * Disallow directory write attempts on read-only 685 * file systems. 686 */ 687 if (rdonly || (dp->v_mount->mnt_flag & MNT_RDONLY) || 688 (wantparent && 689 (dvp->v_mount->mnt_flag & MNT_RDONLY))) { 690 error = EROFS; 691 goto bad2; 692 } 693 } 694 /* ASSERT(dvp == ndp->ni_startdir) */ 695 if (cnp->cn_flags & SAVESTART) 696 VREF(dvp); 697 if (!wantparent) 698 vrele(dvp); 699 if ((cnp->cn_flags & LOCKLEAF) == 0) 700 VOP_UNLOCK(dp); 701 return (0); 702 703 bad2: 704 if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN)) 705 VOP_UNLOCK(dvp); 706 vrele(dvp); 707 bad: 708 vput(dp); 709 *vpp = NULL; 710 return (error); 711 } 712