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 ndp->ni_topdir = fdp->fd_jdir; 134 135 dp = fdp->fd_cdir; 136 VREF(dp); 137 for (;;) { 138 /* 139 * Check if root directory should replace current directory. 140 * Done at start of translation and after symbolic link. 141 */ 142 cnp->cn_nameptr = cnp->cn_pnbuf; 143 if (*(cnp->cn_nameptr) == '/') { 144 vrele(dp); 145 while (*(cnp->cn_nameptr) == '/') { 146 cnp->cn_nameptr++; 147 ndp->ni_pathlen--; 148 } 149 dp = ndp->ni_rootdir; 150 VREF(dp); 151 } 152 ndp->ni_startdir = dp; 153 error = lookup(ndp); 154 if (error) { 155 zfree(namei_zone, cnp->cn_pnbuf); 156 return (error); 157 } 158 /* 159 * Check for symbolic link 160 */ 161 if ((cnp->cn_flags & ISSYMLINK) == 0) { 162 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) 163 zfree(namei_zone, cnp->cn_pnbuf); 164 else 165 cnp->cn_flags |= HASBUF; 166 167 if (vn_canvmio(ndp->ni_vp) == TRUE && 168 (cnp->cn_nameiop != DELETE) && 169 ((cnp->cn_flags & (NOOBJ|LOCKLEAF)) == 170 LOCKLEAF)) 171 vfs_object_create(ndp->ni_vp, 172 ndp->ni_cnd.cn_proc, 173 ndp->ni_cnd.cn_cred); 174 175 return (0); 176 } 177 if ((cnp->cn_flags & LOCKPARENT) && ndp->ni_pathlen == 1) 178 VOP_UNLOCK(ndp->ni_dvp, 0, p); 179 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) { 180 error = ELOOP; 181 break; 182 } 183 if (ndp->ni_pathlen > 1) 184 cp = zalloc(namei_zone); 185 else 186 cp = cnp->cn_pnbuf; 187 aiov.iov_base = cp; 188 aiov.iov_len = MAXPATHLEN; 189 auio.uio_iov = &aiov; 190 auio.uio_iovcnt = 1; 191 auio.uio_offset = 0; 192 auio.uio_rw = UIO_READ; 193 auio.uio_segflg = UIO_SYSSPACE; 194 auio.uio_procp = (struct proc *)0; 195 auio.uio_resid = MAXPATHLEN; 196 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred); 197 if (error) { 198 if (ndp->ni_pathlen > 1) 199 zfree(namei_zone, cp); 200 break; 201 } 202 linklen = MAXPATHLEN - auio.uio_resid; 203 if (linklen == 0) { 204 if (ndp->ni_pathlen > 1) 205 zfree(namei_zone, cp); 206 error = ENOENT; 207 break; 208 } 209 if (linklen + ndp->ni_pathlen >= MAXPATHLEN) { 210 if (ndp->ni_pathlen > 1) 211 zfree(namei_zone, cp); 212 error = ENAMETOOLONG; 213 break; 214 } 215 if (ndp->ni_pathlen > 1) { 216 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen); 217 zfree(namei_zone, cnp->cn_pnbuf); 218 cnp->cn_pnbuf = cp; 219 } else 220 cnp->cn_pnbuf[linklen] = '\0'; 221 ndp->ni_pathlen += linklen; 222 vput(ndp->ni_vp); 223 dp = ndp->ni_dvp; 224 } 225 zfree(namei_zone, cnp->cn_pnbuf); 226 vrele(ndp->ni_dvp); 227 vput(ndp->ni_vp); 228 ndp->ni_vp = NULL; 229 return (error); 230 } 231 232 /* 233 * Search a pathname. 234 * This is a very central and rather complicated routine. 235 * 236 * The pathname is pointed to by ni_ptr and is of length ni_pathlen. 237 * The starting directory is taken from ni_startdir. The pathname is 238 * descended until done, or a symbolic link is encountered. The variable 239 * ni_more is clear if the path is completed; it is set to one if a 240 * symbolic link needing interpretation is encountered. 241 * 242 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 243 * whether the name is to be looked up, created, renamed, or deleted. 244 * When CREATE, RENAME, or DELETE is specified, information usable in 245 * creating, renaming, or deleting a directory entry may be calculated. 246 * If flag has LOCKPARENT or'ed into it, the parent directory is returned 247 * locked. If flag has WANTPARENT or'ed into it, the parent directory is 248 * returned unlocked. Otherwise the parent directory is not returned. If 249 * the target of the pathname exists and LOCKLEAF is or'ed into the flag 250 * the target is returned locked, otherwise it is returned unlocked. 251 * When creating or renaming and LOCKPARENT is specified, the target may not 252 * be ".". When deleting and LOCKPARENT is specified, the target may be ".". 253 * 254 * Overall outline of lookup: 255 * 256 * dirloop: 257 * identify next component of name at ndp->ni_ptr 258 * handle degenerate case where name is null string 259 * if .. and crossing mount points and on mounted filesys, find parent 260 * call VOP_LOOKUP routine for next component name 261 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set 262 * component vnode returned in ni_vp (if it exists), locked. 263 * if result vnode is mounted on and crossing mount points, 264 * find mounted on vnode 265 * if more components of name, do next level at dirloop 266 * return the answer in ni_vp, locked if LOCKLEAF set 267 * if LOCKPARENT set, return locked parent in ni_dvp 268 * if WANTPARENT set, return unlocked parent in ni_dvp 269 */ 270 int 271 lookup(ndp) 272 register struct nameidata *ndp; 273 { 274 register char *cp; /* pointer into pathname argument */ 275 register struct vnode *dp = 0; /* the directory we are searching */ 276 struct vnode *tdp; /* saved dp */ 277 struct mount *mp; /* mount table entry */ 278 int docache; /* == 0 do not cache last component */ 279 int wantparent; /* 1 => wantparent or lockparent flag */ 280 int rdonly; /* lookup read-only flag bit */ 281 int trailing_slash; 282 int error = 0; 283 int dpunlocked = 0; /* dp has already been unlocked */ 284 struct componentname *cnp = &ndp->ni_cnd; 285 struct proc *p = cnp->cn_proc; 286 287 /* 288 * Setup: break out flag bits into variables. 289 */ 290 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT); 291 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 292 if (cnp->cn_nameiop == DELETE || 293 (wantparent && cnp->cn_nameiop != CREATE && 294 cnp->cn_nameiop != LOOKUP)) 295 docache = 0; 296 rdonly = cnp->cn_flags & RDONLY; 297 ndp->ni_dvp = NULL; 298 cnp->cn_flags &= ~ISSYMLINK; 299 dp = ndp->ni_startdir; 300 ndp->ni_startdir = NULLVP; 301 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY, p); 302 303 dirloop: 304 /* 305 * Search a new directory. 306 * 307 * The last component of the filename is left accessible via 308 * cnp->cn_nameptr for callers that need the name. Callers needing 309 * the name set the SAVENAME flag. When done, they assume 310 * responsibility for freeing the pathname buffer. 311 */ 312 cnp->cn_consume = 0; 313 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++) 314 continue; 315 cnp->cn_namelen = cp - cnp->cn_nameptr; 316 if (cnp->cn_namelen > NAME_MAX) { 317 error = ENAMETOOLONG; 318 goto bad; 319 } 320 #ifdef NAMEI_DIAGNOSTIC 321 { char c = *cp; 322 *cp = '\0'; 323 printf("{%s}: ", cnp->cn_nameptr); 324 *cp = c; } 325 #endif 326 ndp->ni_pathlen -= cnp->cn_namelen; 327 ndp->ni_next = cp; 328 329 /* 330 * Replace multiple slashes by a single slash and trailing slashes 331 * by a null. This must be done before VOP_LOOKUP() because some 332 * fs's don't know about trailing slashes. Remember if there were 333 * trailing slashes to handle symlinks, existing non-directories 334 * and non-existing files that won't be directories specially later. 335 */ 336 trailing_slash = 0; 337 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) { 338 cp++; 339 ndp->ni_pathlen--; 340 if (*cp == '\0') { 341 trailing_slash = 1; 342 *ndp->ni_next = '\0'; /* XXX for direnter() ... */ 343 } 344 } 345 ndp->ni_next = cp; 346 347 cnp->cn_flags |= MAKEENTRY; 348 if (*cp == '\0' && docache == 0) 349 cnp->cn_flags &= ~MAKEENTRY; 350 if (cnp->cn_namelen == 2 && 351 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') 352 cnp->cn_flags |= ISDOTDOT; 353 else 354 cnp->cn_flags &= ~ISDOTDOT; 355 if (*ndp->ni_next == 0) 356 cnp->cn_flags |= ISLASTCN; 357 else 358 cnp->cn_flags &= ~ISLASTCN; 359 360 361 /* 362 * Check for degenerate name (e.g. / or "") 363 * which is a way of talking about a directory, 364 * e.g. like "/." or ".". 365 */ 366 if (cnp->cn_nameptr[0] == '\0') { 367 if (dp->v_type != VDIR) { 368 error = ENOTDIR; 369 goto bad; 370 } 371 if (cnp->cn_nameiop != LOOKUP) { 372 error = EISDIR; 373 goto bad; 374 } 375 if (wantparent) { 376 ndp->ni_dvp = dp; 377 VREF(dp); 378 } 379 ndp->ni_vp = dp; 380 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF))) 381 VOP_UNLOCK(dp, 0, p); 382 /* XXX This should probably move to the top of function. */ 383 if (cnp->cn_flags & SAVESTART) 384 panic("lookup: SAVESTART"); 385 return (0); 386 } 387 388 /* 389 * Handle "..": two special cases. 390 * 1. If at root directory (e.g. after chroot) 391 * or at absolute root directory 392 * then ignore it so can't get out. 393 * 2. If this vnode is the root of a mounted 394 * filesystem, then replace it with the 395 * vnode which was mounted on so we take the 396 * .. in the other file system. 397 * 3. If the vnode is the top directory of 398 * the jail or chroot, don't let them out. 399 */ 400 if (cnp->cn_flags & ISDOTDOT) { 401 for (;;) { 402 if (dp == ndp->ni_rootdir || 403 dp == ndp->ni_topdir || 404 dp == rootvnode) { 405 ndp->ni_dvp = dp; 406 ndp->ni_vp = dp; 407 VREF(dp); 408 goto nextname; 409 } 410 if ((dp->v_flag & VROOT) == 0 || 411 (cnp->cn_flags & NOCROSSMOUNT)) 412 break; 413 if (dp->v_mount == NULL) { /* forced unmount */ 414 error = EBADF; 415 goto bad; 416 } 417 tdp = dp; 418 dp = dp->v_mount->mnt_vnodecovered; 419 vput(tdp); 420 VREF(dp); 421 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY, p); 422 } 423 } 424 425 /* 426 * We now have a segment name to search for, and a directory to search. 427 */ 428 unionlookup: 429 ndp->ni_dvp = dp; 430 ndp->ni_vp = NULL; 431 cnp->cn_flags &= ~PDIRUNLOCK; 432 ASSERT_VOP_LOCKED(dp, "lookup"); 433 if ((error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) != 0) { 434 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty")); 435 #ifdef NAMEI_DIAGNOSTIC 436 printf("not found\n"); 437 #endif 438 if ((error == ENOENT) && 439 (dp->v_flag & VROOT) && (dp->v_mount != NULL) && 440 (dp->v_mount->mnt_flag & MNT_UNION)) { 441 tdp = dp; 442 dp = dp->v_mount->mnt_vnodecovered; 443 if (cnp->cn_flags & PDIRUNLOCK) 444 vrele(tdp); 445 else 446 vput(tdp); 447 VREF(dp); 448 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY, p); 449 goto unionlookup; 450 } 451 452 if (error != EJUSTRETURN) 453 goto bad; 454 /* 455 * If creating and at end of pathname, then can consider 456 * allowing file to be created. 457 */ 458 if (rdonly) { 459 error = EROFS; 460 goto bad; 461 } 462 if (*cp == '\0' && trailing_slash && 463 !(cnp->cn_flags & WILLBEDIR)) { 464 error = ENOENT; 465 goto bad; 466 } 467 /* 468 * We return with ni_vp NULL to indicate that the entry 469 * doesn't currently exist, leaving a pointer to the 470 * (possibly locked) directory inode in ndp->ni_dvp. 471 */ 472 if (cnp->cn_flags & SAVESTART) { 473 ndp->ni_startdir = ndp->ni_dvp; 474 VREF(ndp->ni_startdir); 475 } 476 return (0); 477 } 478 #ifdef NAMEI_DIAGNOSTIC 479 printf("found\n"); 480 #endif 481 482 ASSERT_VOP_LOCKED(ndp->ni_vp, "lookup"); 483 484 /* 485 * Take into account any additional components consumed by 486 * the underlying filesystem. 487 */ 488 if (cnp->cn_consume > 0) { 489 cnp->cn_nameptr += cnp->cn_consume; 490 ndp->ni_next += cnp->cn_consume; 491 ndp->ni_pathlen -= cnp->cn_consume; 492 cnp->cn_consume = 0; 493 } 494 495 dp = ndp->ni_vp; 496 497 /* 498 * Check to see if the vnode has been mounted on; 499 * if so find the root of the mounted file system. 500 */ 501 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) && 502 (cnp->cn_flags & NOCROSSMOUNT) == 0) { 503 if (vfs_busy(mp, 0, 0, p)) 504 continue; 505 VOP_UNLOCK(dp, 0, p); 506 error = VFS_ROOT(mp, &tdp); 507 vfs_unbusy(mp, p); 508 if (error) { 509 dpunlocked = 1; 510 goto bad2; 511 } 512 vrele(dp); 513 ndp->ni_vp = dp = tdp; 514 } 515 516 /* 517 * Check for symbolic link 518 */ 519 if ((dp->v_type == VLNK) && 520 ((cnp->cn_flags & FOLLOW) || trailing_slash || 521 *ndp->ni_next == '/')) { 522 cnp->cn_flags |= ISSYMLINK; 523 if (dp->v_mount == NULL) { 524 /* We can't know whether the directory was mounted with 525 * NOSYMFOLLOW, so we can't follow safely. */ 526 error = EBADF; 527 goto bad2; 528 } 529 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) { 530 error = EACCES; 531 goto bad2; 532 } 533 return (0); 534 } 535 536 /* 537 * Check for bogus trailing slashes. 538 */ 539 if (trailing_slash && dp->v_type != VDIR) { 540 error = ENOTDIR; 541 goto bad2; 542 } 543 544 nextname: 545 /* 546 * Not a symbolic link. If more pathname, 547 * continue at next component, else return. 548 */ 549 if (*ndp->ni_next == '/') { 550 cnp->cn_nameptr = ndp->ni_next; 551 while (*cnp->cn_nameptr == '/') { 552 cnp->cn_nameptr++; 553 ndp->ni_pathlen--; 554 } 555 if (ndp->ni_dvp != ndp->ni_vp) 556 ASSERT_VOP_UNLOCKED(ndp->ni_dvp, "lookup"); 557 vrele(ndp->ni_dvp); 558 goto dirloop; 559 } 560 /* 561 * Disallow directory write attempts on read-only file systems. 562 */ 563 if (rdonly && 564 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 565 error = EROFS; 566 goto bad2; 567 } 568 if (cnp->cn_flags & SAVESTART) { 569 ndp->ni_startdir = ndp->ni_dvp; 570 VREF(ndp->ni_startdir); 571 } 572 if (!wantparent) 573 vrele(ndp->ni_dvp); 574 575 if ((cnp->cn_flags & LOCKLEAF) == 0) 576 VOP_UNLOCK(dp, 0, p); 577 return (0); 578 579 bad2: 580 if ((cnp->cn_flags & (LOCKPARENT | PDIRUNLOCK)) == LOCKPARENT && 581 *ndp->ni_next == '\0') 582 VOP_UNLOCK(ndp->ni_dvp, 0, p); 583 vrele(ndp->ni_dvp); 584 bad: 585 if (dpunlocked) 586 vrele(dp); 587 else 588 vput(dp); 589 ndp->ni_vp = NULL; 590 return (error); 591 } 592 593 /* 594 * relookup - lookup a path name component 595 * Used by lookup to re-aquire things. 596 */ 597 int 598 relookup(dvp, vpp, cnp) 599 struct vnode *dvp, **vpp; 600 struct componentname *cnp; 601 { 602 struct proc *p = cnp->cn_proc; 603 struct vnode *dp = 0; /* the directory we are searching */ 604 int docache; /* == 0 do not cache last component */ 605 int wantparent; /* 1 => wantparent or lockparent flag */ 606 int rdonly; /* lookup read-only flag bit */ 607 int error = 0; 608 #ifdef NAMEI_DIAGNOSTIC 609 int newhash; /* DEBUG: check name hash */ 610 char *cp; /* DEBUG: check name ptr/len */ 611 #endif 612 613 /* 614 * Setup: break out flag bits into variables. 615 */ 616 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT); 617 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 618 if (cnp->cn_nameiop == DELETE || 619 (wantparent && cnp->cn_nameiop != CREATE)) 620 docache = 0; 621 rdonly = cnp->cn_flags & RDONLY; 622 cnp->cn_flags &= ~ISSYMLINK; 623 dp = dvp; 624 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY, p); 625 626 /* dirloop: */ 627 /* 628 * Search a new directory. 629 * 630 * The last component of the filename is left accessible via 631 * cnp->cn_nameptr for callers that need the name. Callers needing 632 * the name set the SAVENAME flag. When done, they assume 633 * responsibility for freeing the pathname buffer. 634 */ 635 #ifdef NAMEI_DIAGNOSTIC 636 if (cnp->cn_namelen != cp - cnp->cn_nameptr) 637 panic ("relookup: bad len"); 638 if (*cp != 0) 639 panic("relookup: not last component"); 640 printf("{%s}: ", cnp->cn_nameptr); 641 #endif 642 643 /* 644 * Check for degenerate name (e.g. / or "") 645 * which is a way of talking about a directory, 646 * e.g. like "/." or ".". 647 */ 648 if (cnp->cn_nameptr[0] == '\0') { 649 if (cnp->cn_nameiop != LOOKUP || wantparent) { 650 error = EISDIR; 651 goto bad; 652 } 653 if (dp->v_type != VDIR) { 654 error = ENOTDIR; 655 goto bad; 656 } 657 if (!(cnp->cn_flags & LOCKLEAF)) 658 VOP_UNLOCK(dp, 0, p); 659 *vpp = dp; 660 /* XXX This should probably move to the top of function. */ 661 if (cnp->cn_flags & SAVESTART) 662 panic("lookup: SAVESTART"); 663 return (0); 664 } 665 666 if (cnp->cn_flags & ISDOTDOT) 667 panic ("relookup: lookup on dot-dot"); 668 669 /* 670 * We now have a segment name to search for, and a directory to search. 671 */ 672 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) { 673 KASSERT(*vpp == NULL, ("leaf should be empty")); 674 if (error != EJUSTRETURN) 675 goto bad; 676 /* 677 * If creating and at end of pathname, then can consider 678 * allowing file to be created. 679 */ 680 if (rdonly) { 681 error = EROFS; 682 goto bad; 683 } 684 /* ASSERT(dvp == ndp->ni_startdir) */ 685 if (cnp->cn_flags & SAVESTART) 686 VREF(dvp); 687 /* 688 * We return with ni_vp NULL to indicate that the entry 689 * doesn't currently exist, leaving a pointer to the 690 * (possibly locked) directory inode in ndp->ni_dvp. 691 */ 692 return (0); 693 } 694 dp = *vpp; 695 696 /* 697 * Check for symbolic link 698 */ 699 KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW), 700 ("relookup: symlink found.\n")); 701 702 /* 703 * Disallow directory write attempts on read-only file systems. 704 */ 705 if (rdonly && 706 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 707 error = EROFS; 708 goto bad2; 709 } 710 /* ASSERT(dvp == ndp->ni_startdir) */ 711 if (cnp->cn_flags & SAVESTART) 712 VREF(dvp); 713 714 if (!wantparent) 715 vrele(dvp); 716 717 if (vn_canvmio(dp) == TRUE && 718 ((cnp->cn_flags & (NOOBJ|LOCKLEAF)) == LOCKLEAF)) 719 vfs_object_create(dp, cnp->cn_proc, cnp->cn_cred); 720 721 if ((cnp->cn_flags & LOCKLEAF) == 0) 722 VOP_UNLOCK(dp, 0, p); 723 return (0); 724 725 bad2: 726 if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN)) 727 VOP_UNLOCK(dvp, 0, p); 728 vrele(dvp); 729 bad: 730 vput(dp); 731 *vpp = NULL; 732 return (error); 733 }
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