| 1 | /* |
| 2 | * Copyright (c) 1989 The Regents of the University of California. |
| 3 | * All rights reserved. |
| 4 | * |
| 5 | * %sccs.include.redist.c% |
| 6 | * |
| 7 | * @(#)ufs_lookup.c 7.29 (Berkeley) %G% |
| 8 | */ |
| 9 | |
| 10 | #include "param.h" |
| 11 | #include "namei.h" |
| 12 | #include "buf.h" |
| 13 | #include "file.h" |
| 14 | #include "vnode.h" |
| 15 | |
| 16 | #include "quota.h" |
| 17 | #include "inode.h" |
| 18 | #include "fs.h" |
| 19 | |
| 20 | struct nchstats nchstats; |
| 21 | int dirchk = 1; |
| 22 | |
| 23 | /* |
| 24 | * Convert a component of a pathname into a pointer to a locked inode. |
| 25 | * This is a very central and rather complicated routine. |
| 26 | * If the file system is not maintained in a strict tree hierarchy, |
| 27 | * this can result in a deadlock situation (see comments in code below). |
| 28 | * |
| 29 | * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on |
| 30 | * whether the name is to be looked up, created, renamed, or deleted. |
| 31 | * When CREATE, RENAME, or DELETE is specified, information usable in |
| 32 | * creating, renaming, or deleting a directory entry may be calculated. |
| 33 | * If flag has LOCKPARENT or'ed into it and the target of the pathname |
| 34 | * exists, lookup returns both the target and its parent directory locked. |
| 35 | * When creating or renaming and LOCKPARENT is specified, the target may |
| 36 | * not be ".". When deleting and LOCKPARENT is specified, the target may |
| 37 | * be "."., but the caller must check to ensure it does an vrele and iput |
| 38 | * instead of two iputs. |
| 39 | * |
| 40 | * Overall outline of ufs_lookup: |
| 41 | * |
| 42 | * check accessibility of directory |
| 43 | * look for name in cache, if found, then if at end of path |
| 44 | * and deleting or creating, drop it, else return name |
| 45 | * search for name in directory, to found or notfound |
| 46 | * notfound: |
| 47 | * if creating, return locked directory, leaving info on available slots |
| 48 | * else return error |
| 49 | * found: |
| 50 | * if at end of path and deleting, return information to allow delete |
| 51 | * if at end of path and rewriting (RENAME and LOCKPARENT), lock target |
| 52 | * inode and return info to allow rewrite |
| 53 | * if not at end, add name to cache; if at end and neither creating |
| 54 | * nor deleting, add name to cache |
| 55 | * |
| 56 | * NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode unlocked. |
| 57 | */ |
| 58 | ufs_lookup(vdp, ndp, p) |
| 59 | register struct vnode *vdp; |
| 60 | register struct nameidata *ndp; |
| 61 | struct proc *p; |
| 62 | { |
| 63 | register struct inode *dp; /* the directory we are searching */ |
| 64 | register struct fs *fs; /* file system that directory is in */ |
| 65 | struct buf *bp = 0; /* a buffer of directory entries */ |
| 66 | register struct direct *ep; /* the current directory entry */ |
| 67 | int entryoffsetinblock; /* offset of ep in bp's buffer */ |
| 68 | enum {NONE, COMPACT, FOUND} slotstatus; |
| 69 | int slotoffset = -1; /* offset of area with free space */ |
| 70 | int slotsize; /* size of area at slotoffset */ |
| 71 | int slotfreespace; /* amount of space free in slot */ |
| 72 | int slotneeded; /* size of the entry we're seeking */ |
| 73 | int numdirpasses; /* strategy for directory search */ |
| 74 | int endsearch; /* offset to end directory search */ |
| 75 | int prevoff; /* ndp->ni_offset of previous entry */ |
| 76 | struct inode *pdp; /* saved dp during symlink work */ |
| 77 | struct inode *tdp; /* returned by iget */ |
| 78 | off_t enduseful; /* pointer past last used dir slot */ |
| 79 | int flag; /* LOOKUP, CREATE, RENAME, or DELETE */ |
| 80 | int lockparent; /* 1 => lockparent flag is set */ |
| 81 | int wantparent; /* 1 => wantparent or lockparent flag */ |
| 82 | int error; |
| 83 | |
| 84 | ndp->ni_dvp = vdp; |
| 85 | ndp->ni_vp = NULL; |
| 86 | dp = VTOI(vdp); |
| 87 | fs = dp->i_fs; |
| 88 | lockparent = ndp->ni_nameiop & LOCKPARENT; |
| 89 | flag = ndp->ni_nameiop & OPMASK; |
| 90 | wantparent = ndp->ni_nameiop & (LOCKPARENT|WANTPARENT); |
| 91 | |
| 92 | /* |
| 93 | * Check accessiblity of directory. |
| 94 | */ |
| 95 | if ((dp->i_mode&IFMT) != IFDIR) |
| 96 | return (ENOTDIR); |
| 97 | if (error = ufs_access(vdp, VEXEC, ndp->ni_cred, p)) |
| 98 | return (error); |
| 99 | |
| 100 | /* |
| 101 | * We now have a segment name to search for, and a directory to search. |
| 102 | * |
| 103 | * Before tediously performing a linear scan of the directory, |
| 104 | * check the name cache to see if the directory/name pair |
| 105 | * we are looking for is known already. |
| 106 | */ |
| 107 | if (error = cache_lookup(ndp)) { |
| 108 | int vpid; /* capability number of vnode */ |
| 109 | |
| 110 | if (error == ENOENT) |
| 111 | return (error); |
| 112 | #ifdef PARANOID |
| 113 | if (vdp == ndp->ni_rdir && ndp->ni_isdotdot) |
| 114 | panic("ufs_lookup: .. through root"); |
| 115 | #endif |
| 116 | /* |
| 117 | * Get the next vnode in the path. |
| 118 | * See comment below starting `Step through' for |
| 119 | * an explaination of the locking protocol. |
| 120 | */ |
| 121 | pdp = dp; |
| 122 | dp = VTOI(ndp->ni_vp); |
| 123 | vdp = ndp->ni_vp; |
| 124 | vpid = vdp->v_id; |
| 125 | if (pdp == dp) { |
| 126 | VREF(vdp); |
| 127 | error = 0; |
| 128 | } else if (ndp->ni_isdotdot) { |
| 129 | IUNLOCK(pdp); |
| 130 | error = vget(vdp); |
| 131 | if (!error && lockparent && *ndp->ni_next == '\0') |
| 132 | ILOCK(pdp); |
| 133 | } else { |
| 134 | error = vget(vdp); |
| 135 | if (!lockparent || error || *ndp->ni_next != '\0') |
| 136 | IUNLOCK(pdp); |
| 137 | } |
| 138 | /* |
| 139 | * Check that the capability number did not change |
| 140 | * while we were waiting for the lock. |
| 141 | */ |
| 142 | if (!error) { |
| 143 | if (vpid == vdp->v_id) |
| 144 | return (0); |
| 145 | iput(dp); |
| 146 | if (lockparent && pdp != dp && *ndp->ni_next == '\0') |
| 147 | IUNLOCK(pdp); |
| 148 | } |
| 149 | ILOCK(pdp); |
| 150 | dp = pdp; |
| 151 | vdp = ITOV(dp); |
| 152 | ndp->ni_vp = NULL; |
| 153 | } |
| 154 | |
| 155 | /* |
| 156 | * Suppress search for slots unless creating |
| 157 | * file and at end of pathname, in which case |
| 158 | * we watch for a place to put the new file in |
| 159 | * case it doesn't already exist. |
| 160 | */ |
| 161 | slotstatus = FOUND; |
| 162 | if ((flag == CREATE || flag == RENAME) && *ndp->ni_next == 0) { |
| 163 | slotstatus = NONE; |
| 164 | slotfreespace = 0; |
| 165 | slotneeded = DIRSIZ(&ndp->ni_dent); |
| 166 | } |
| 167 | |
| 168 | /* |
| 169 | * If there is cached information on a previous search of |
| 170 | * this directory, pick up where we last left off. |
| 171 | * We cache only lookups as these are the most common |
| 172 | * and have the greatest payoff. Caching CREATE has little |
| 173 | * benefit as it usually must search the entire directory |
| 174 | * to determine that the entry does not exist. Caching the |
| 175 | * location of the last DELETE or RENAME has not reduced |
| 176 | * profiling time and hence has been removed in the interest |
| 177 | * of simplicity. |
| 178 | */ |
| 179 | if (flag != LOOKUP || dp->i_diroff == 0 || dp->i_diroff > dp->i_size) { |
| 180 | ndp->ni_offset = 0; |
| 181 | numdirpasses = 1; |
| 182 | } else { |
| 183 | ndp->ni_offset = dp->i_diroff; |
| 184 | entryoffsetinblock = blkoff(fs, ndp->ni_offset); |
| 185 | if (entryoffsetinblock != 0) { |
| 186 | error = blkatoff(dp, ndp->ni_offset, (char **)0, &bp); |
| 187 | if (error) |
| 188 | return (error); |
| 189 | } |
| 190 | numdirpasses = 2; |
| 191 | nchstats.ncs_2passes++; |
| 192 | } |
| 193 | endsearch = roundup(dp->i_size, DIRBLKSIZ); |
| 194 | enduseful = 0; |
| 195 | |
| 196 | searchloop: |
| 197 | while (ndp->ni_offset < endsearch) { |
| 198 | /* |
| 199 | * If offset is on a block boundary, |
| 200 | * read the next directory block. |
| 201 | * Release previous if it exists. |
| 202 | */ |
| 203 | if (blkoff(fs, ndp->ni_offset) == 0) { |
| 204 | if (bp != NULL) |
| 205 | brelse(bp); |
| 206 | error = blkatoff(dp, ndp->ni_offset, (char **)0, &bp); |
| 207 | if (error) |
| 208 | return (error); |
| 209 | entryoffsetinblock = 0; |
| 210 | } |
| 211 | /* |
| 212 | * If still looking for a slot, and at a DIRBLKSIZE |
| 213 | * boundary, have to start looking for free space again. |
| 214 | */ |
| 215 | if (slotstatus == NONE && |
| 216 | (entryoffsetinblock & (DIRBLKSIZ - 1)) == 0) { |
| 217 | slotoffset = -1; |
| 218 | slotfreespace = 0; |
| 219 | } |
| 220 | /* |
| 221 | * Get pointer to next entry. |
| 222 | * Full validation checks are slow, so we only check |
| 223 | * enough to insure forward progress through the |
| 224 | * directory. Complete checks can be run by patching |
| 225 | * "dirchk" to be true. |
| 226 | */ |
| 227 | ep = (struct direct *)(bp->b_un.b_addr + entryoffsetinblock); |
| 228 | if (ep->d_reclen == 0 || |
| 229 | dirchk && dirbadentry(ep, entryoffsetinblock)) { |
| 230 | int i; |
| 231 | |
| 232 | dirbad(dp, ndp->ni_offset, "mangled entry"); |
| 233 | i = DIRBLKSIZ - (entryoffsetinblock & (DIRBLKSIZ - 1)); |
| 234 | ndp->ni_offset += i; |
| 235 | entryoffsetinblock += i; |
| 236 | continue; |
| 237 | } |
| 238 | |
| 239 | /* |
| 240 | * If an appropriate sized slot has not yet been found, |
| 241 | * check to see if one is available. Also accumulate space |
| 242 | * in the current block so that we can determine if |
| 243 | * compaction is viable. |
| 244 | */ |
| 245 | if (slotstatus != FOUND) { |
| 246 | int size = ep->d_reclen; |
| 247 | |
| 248 | if (ep->d_ino != 0) |
| 249 | size -= DIRSIZ(ep); |
| 250 | if (size > 0) { |
| 251 | if (size >= slotneeded) { |
| 252 | slotstatus = FOUND; |
| 253 | slotoffset = ndp->ni_offset; |
| 254 | slotsize = ep->d_reclen; |
| 255 | } else if (slotstatus == NONE) { |
| 256 | slotfreespace += size; |
| 257 | if (slotoffset == -1) |
| 258 | slotoffset = ndp->ni_offset; |
| 259 | if (slotfreespace >= slotneeded) { |
| 260 | slotstatus = COMPACT; |
| 261 | slotsize = ndp->ni_offset + |
| 262 | ep->d_reclen - slotoffset; |
| 263 | } |
| 264 | } |
| 265 | } |
| 266 | } |
| 267 | |
| 268 | /* |
| 269 | * Check for a name match. |
| 270 | */ |
| 271 | if (ep->d_ino) { |
| 272 | if (ep->d_namlen == ndp->ni_dent.d_namlen && |
| 273 | !bcmp(ndp->ni_ptr, ep->d_name, |
| 274 | (unsigned)ep->d_namlen)) { |
| 275 | /* |
| 276 | * Save directory entry's inode number and |
| 277 | * reclen in ndp->ni_dent, and release |
| 278 | * directory buffer. |
| 279 | */ |
| 280 | ndp->ni_dent.d_ino = ep->d_ino; |
| 281 | ndp->ni_dent.d_reclen = ep->d_reclen; |
| 282 | brelse(bp); |
| 283 | goto found; |
| 284 | } |
| 285 | } |
| 286 | prevoff = ndp->ni_offset; |
| 287 | ndp->ni_offset += ep->d_reclen; |
| 288 | entryoffsetinblock += ep->d_reclen; |
| 289 | if (ep->d_ino) |
| 290 | enduseful = ndp->ni_offset; |
| 291 | } |
| 292 | /* notfound: */ |
| 293 | /* |
| 294 | * If we started in the middle of the directory and failed |
| 295 | * to find our target, we must check the beginning as well. |
| 296 | */ |
| 297 | if (numdirpasses == 2) { |
| 298 | numdirpasses--; |
| 299 | ndp->ni_offset = 0; |
| 300 | endsearch = dp->i_diroff; |
| 301 | goto searchloop; |
| 302 | } |
| 303 | if (bp != NULL) |
| 304 | brelse(bp); |
| 305 | /* |
| 306 | * If creating, and at end of pathname and current |
| 307 | * directory has not been removed, then can consider |
| 308 | * allowing file to be created. |
| 309 | */ |
| 310 | if ((flag == CREATE || flag == RENAME) && |
| 311 | *ndp->ni_next == 0 && dp->i_nlink != 0) { |
| 312 | /* |
| 313 | * Access for write is interpreted as allowing |
| 314 | * creation of files in the directory. |
| 315 | */ |
| 316 | if (error = ufs_access(vdp, VWRITE, ndp->ni_cred, p)) |
| 317 | return (error); |
| 318 | /* |
| 319 | * Return an indication of where the new directory |
| 320 | * entry should be put. If we didn't find a slot, |
| 321 | * then set ndp->ni_count to 0 indicating that the new |
| 322 | * slot belongs at the end of the directory. If we found |
| 323 | * a slot, then the new entry can be put in the range |
| 324 | * [ndp->ni_offset .. ndp->ni_offset + ndp->ni_count) |
| 325 | */ |
| 326 | if (slotstatus == NONE) { |
| 327 | ndp->ni_offset = roundup(dp->i_size, DIRBLKSIZ); |
| 328 | ndp->ni_count = 0; |
| 329 | enduseful = ndp->ni_offset; |
| 330 | } else { |
| 331 | ndp->ni_offset = slotoffset; |
| 332 | ndp->ni_count = slotsize; |
| 333 | if (enduseful < slotoffset + slotsize) |
| 334 | enduseful = slotoffset + slotsize; |
| 335 | } |
| 336 | ndp->ni_endoff = roundup(enduseful, DIRBLKSIZ); |
| 337 | dp->i_flag |= IUPD|ICHG; |
| 338 | /* |
| 339 | * We return with the directory locked, so that |
| 340 | * the parameters we set up above will still be |
| 341 | * valid if we actually decide to do a direnter(). |
| 342 | * We return ni_vp == NULL to indicate that the entry |
| 343 | * does not currently exist; we leave a pointer to |
| 344 | * the (locked) directory inode in ndp->ni_dvp. |
| 345 | * |
| 346 | * NB - if the directory is unlocked, then this |
| 347 | * information cannot be used. |
| 348 | */ |
| 349 | if (!lockparent) |
| 350 | IUNLOCK(dp); |
| 351 | } |
| 352 | /* |
| 353 | * Insert name into cache (as non-existent) if appropriate. |
| 354 | */ |
| 355 | if (ndp->ni_makeentry && flag != CREATE) |
| 356 | cache_enter(ndp); |
| 357 | return (ENOENT); |
| 358 | |
| 359 | found: |
| 360 | if (numdirpasses == 2) |
| 361 | nchstats.ncs_pass2++; |
| 362 | /* |
| 363 | * Check that directory length properly reflects presence |
| 364 | * of this entry. |
| 365 | */ |
| 366 | if (entryoffsetinblock + DIRSIZ(ep) > dp->i_size) { |
| 367 | dirbad(dp, ndp->ni_offset, "i_size too small"); |
| 368 | dp->i_size = entryoffsetinblock + DIRSIZ(ep); |
| 369 | dp->i_flag |= IUPD|ICHG; |
| 370 | } |
| 371 | |
| 372 | /* |
| 373 | * Found component in pathname. |
| 374 | * If the final component of path name, save information |
| 375 | * in the cache as to where the entry was found. |
| 376 | */ |
| 377 | if (*ndp->ni_next == '\0' && flag == LOOKUP) |
| 378 | dp->i_diroff = ndp->ni_offset &~ (DIRBLKSIZ - 1); |
| 379 | |
| 380 | /* |
| 381 | * If deleting, and at end of pathname, return |
| 382 | * parameters which can be used to remove file. |
| 383 | * If the wantparent flag isn't set, we return only |
| 384 | * the directory (in ndp->ni_dvp), otherwise we go |
| 385 | * on and lock the inode, being careful with ".". |
| 386 | */ |
| 387 | if (flag == DELETE && *ndp->ni_next == 0) { |
| 388 | /* |
| 389 | * Write access to directory required to delete files. |
| 390 | */ |
| 391 | if (error = ufs_access(vdp, VWRITE, ndp->ni_cred, p)) |
| 392 | return (error); |
| 393 | /* |
| 394 | * Return pointer to current entry in ndp->ni_offset, |
| 395 | * and distance past previous entry (if there |
| 396 | * is a previous entry in this block) in ndp->ni_count. |
| 397 | * Save directory inode pointer in ndp->ni_dvp for dirremove(). |
| 398 | */ |
| 399 | if ((ndp->ni_offset&(DIRBLKSIZ-1)) == 0) |
| 400 | ndp->ni_count = 0; |
| 401 | else |
| 402 | ndp->ni_count = ndp->ni_offset - prevoff; |
| 403 | if (dp->i_number == ndp->ni_dent.d_ino) { |
| 404 | VREF(vdp); |
| 405 | ndp->ni_vp = vdp; |
| 406 | return (0); |
| 407 | } |
| 408 | if (error = iget(dp, ndp->ni_dent.d_ino, &tdp)) |
| 409 | return (error); |
| 410 | /* |
| 411 | * If directory is "sticky", then user must own |
| 412 | * the directory, or the file in it, else she |
| 413 | * may not delete it (unless she's root). This |
| 414 | * implements append-only directories. |
| 415 | */ |
| 416 | if ((dp->i_mode & ISVTX) && |
| 417 | ndp->ni_cred->cr_uid != 0 && |
| 418 | ndp->ni_cred->cr_uid != dp->i_uid && |
| 419 | tdp->i_uid != ndp->ni_cred->cr_uid) { |
| 420 | iput(tdp); |
| 421 | return (EPERM); |
| 422 | } |
| 423 | ndp->ni_vp = ITOV(tdp); |
| 424 | if (!lockparent) |
| 425 | IUNLOCK(dp); |
| 426 | return (0); |
| 427 | } |
| 428 | |
| 429 | /* |
| 430 | * If rewriting (RENAME), return the inode and the |
| 431 | * information required to rewrite the present directory |
| 432 | * Must get inode of directory entry to verify it's a |
| 433 | * regular file, or empty directory. |
| 434 | */ |
| 435 | if (flag == RENAME && wantparent && *ndp->ni_next == 0) { |
| 436 | if (error = ufs_access(vdp, VWRITE, ndp->ni_cred, p)) |
| 437 | return (error); |
| 438 | /* |
| 439 | * Careful about locking second inode. |
| 440 | * This can only occur if the target is ".". |
| 441 | */ |
| 442 | if (dp->i_number == ndp->ni_dent.d_ino) |
| 443 | return (EISDIR); |
| 444 | if (error = iget(dp, ndp->ni_dent.d_ino, &tdp)) |
| 445 | return (error); |
| 446 | ndp->ni_vp = ITOV(tdp); |
| 447 | if (!lockparent) |
| 448 | IUNLOCK(dp); |
| 449 | return (0); |
| 450 | } |
| 451 | |
| 452 | /* |
| 453 | * Step through the translation in the name. We do not `iput' the |
| 454 | * directory because we may need it again if a symbolic link |
| 455 | * is relative to the current directory. Instead we save it |
| 456 | * unlocked as "pdp". We must get the target inode before unlocking |
| 457 | * the directory to insure that the inode will not be removed |
| 458 | * before we get it. We prevent deadlock by always fetching |
| 459 | * inodes from the root, moving down the directory tree. Thus |
| 460 | * when following backward pointers ".." we must unlock the |
| 461 | * parent directory before getting the requested directory. |
| 462 | * There is a potential race condition here if both the current |
| 463 | * and parent directories are removed before the `iget' for the |
| 464 | * inode associated with ".." returns. We hope that this occurs |
| 465 | * infrequently since we cannot avoid this race condition without |
| 466 | * implementing a sophisticated deadlock detection algorithm. |
| 467 | * Note also that this simple deadlock detection scheme will not |
| 468 | * work if the file system has any hard links other than ".." |
| 469 | * that point backwards in the directory structure. |
| 470 | */ |
| 471 | pdp = dp; |
| 472 | if (ndp->ni_isdotdot) { |
| 473 | IUNLOCK(pdp); /* race to get the inode */ |
| 474 | if (error = iget(dp, ndp->ni_dent.d_ino, &tdp)) { |
| 475 | ILOCK(pdp); |
| 476 | return (error); |
| 477 | } |
| 478 | if (lockparent && *ndp->ni_next == '\0') |
| 479 | ILOCK(pdp); |
| 480 | ndp->ni_vp = ITOV(tdp); |
| 481 | } else if (dp->i_number == ndp->ni_dent.d_ino) { |
| 482 | VREF(vdp); /* we want ourself, ie "." */ |
| 483 | ndp->ni_vp = vdp; |
| 484 | } else { |
| 485 | if (error = iget(dp, ndp->ni_dent.d_ino, &tdp)) |
| 486 | return (error); |
| 487 | if (!lockparent || *ndp->ni_next != '\0') |
| 488 | IUNLOCK(pdp); |
| 489 | ndp->ni_vp = ITOV(tdp); |
| 490 | } |
| 491 | |
| 492 | /* |
| 493 | * Insert name into cache if appropriate. |
| 494 | */ |
| 495 | if (ndp->ni_makeentry) |
| 496 | cache_enter(ndp); |
| 497 | return (0); |
| 498 | } |
| 499 | |
| 500 | |
| 501 | dirbad(ip, offset, how) |
| 502 | struct inode *ip; |
| 503 | off_t offset; |
| 504 | char *how; |
| 505 | { |
| 506 | |
| 507 | printf("%s: bad dir ino %d at offset %d: %s\n", |
| 508 | ip->i_fs->fs_fsmnt, ip->i_number, offset, how); |
| 509 | panic("bad dir"); |
| 510 | } |
| 511 | |
| 512 | /* |
| 513 | * Do consistency checking on a directory entry: |
| 514 | * record length must be multiple of 4 |
| 515 | * entry must fit in rest of its DIRBLKSIZ block |
| 516 | * record must be large enough to contain entry |
| 517 | * name is not longer than MAXNAMLEN |
| 518 | * name must be as long as advertised, and null terminated |
| 519 | */ |
| 520 | dirbadentry(ep, entryoffsetinblock) |
| 521 | register struct direct *ep; |
| 522 | int entryoffsetinblock; |
| 523 | { |
| 524 | register int i; |
| 525 | |
| 526 | if ((ep->d_reclen & 0x3) != 0 || |
| 527 | ep->d_reclen > DIRBLKSIZ - (entryoffsetinblock & (DIRBLKSIZ - 1)) || |
| 528 | ep->d_reclen < DIRSIZ(ep) || ep->d_namlen > MAXNAMLEN) |
| 529 | return (1); |
| 530 | for (i = 0; i < ep->d_namlen; i++) |
| 531 | if (ep->d_name[i] == '\0') |
| 532 | return (1); |
| 533 | return (ep->d_name[i]); |
| 534 | } |
| 535 | |
| 536 | /* |
| 537 | * Write a directory entry after a call to namei, using the parameters |
| 538 | * which it left in nameidata. The argument ip is the inode which the |
| 539 | * new directory entry will refer to. The nameidata field ndp->ni_dvp |
| 540 | * is a pointer to the directory to be written, which was left locked by |
| 541 | * namei. Remaining parameters (ndp->ni_offset, ndp->ni_count) indicate |
| 542 | * how the space for the new entry is to be gotten. |
| 543 | */ |
| 544 | direnter(ip, ndp) |
| 545 | struct inode *ip; |
| 546 | register struct nameidata *ndp; |
| 547 | { |
| 548 | register struct direct *ep, *nep; |
| 549 | register struct inode *dp = VTOI(ndp->ni_dvp); |
| 550 | struct buf *bp; |
| 551 | int loc, spacefree, error = 0; |
| 552 | u_int dsize; |
| 553 | int newentrysize; |
| 554 | char *dirbuf; |
| 555 | |
| 556 | ndp->ni_dent.d_ino = ip->i_number; |
| 557 | newentrysize = DIRSIZ(&ndp->ni_dent); |
| 558 | if (ndp->ni_count == 0) { |
| 559 | /* |
| 560 | * If ndp->ni_count is 0, then namei could find no space in the |
| 561 | * directory. In this case ndp->ni_offset will be on a directory |
| 562 | * block boundary and we will write the new entry into a fresh |
| 563 | * block. |
| 564 | */ |
| 565 | if (ndp->ni_offset&(DIRBLKSIZ-1)) |
| 566 | panic("wdir: newblk"); |
| 567 | ndp->ni_dent.d_reclen = DIRBLKSIZ; |
| 568 | ndp->ni_count = newentrysize; |
| 569 | ndp->ni_resid = newentrysize; |
| 570 | ndp->ni_base = (caddr_t)&ndp->ni_dent; |
| 571 | ndp->ni_iov = &ndp->ni_nd.nd_iovec; |
| 572 | ndp->ni_iovcnt = 1; |
| 573 | ndp->ni_rw = UIO_WRITE; |
| 574 | ndp->ni_uioseg = UIO_SYSSPACE; |
| 575 | error = |
| 576 | ufs_write(ndp->ni_dvp, &ndp->ni_uio, IO_SYNC, ndp->ni_cred); |
| 577 | if (DIRBLKSIZ > dp->i_fs->fs_fsize) { |
| 578 | panic("wdir: blksize"); /* XXX - should grow w/balloc */ |
| 579 | } else { |
| 580 | dp->i_size = roundup(dp->i_size, DIRBLKSIZ); |
| 581 | dp->i_flag |= ICHG; |
| 582 | } |
| 583 | return (error); |
| 584 | } |
| 585 | |
| 586 | /* |
| 587 | * If ndp->ni_count is non-zero, then namei found space for the new |
| 588 | * entry in the range ndp->ni_offset to ndp->ni_offset + ndp->ni_count. |
| 589 | * in the directory. To use this space, we may have to compact |
| 590 | * the entries located there, by copying them together towards |
| 591 | * the beginning of the block, leaving the free space in |
| 592 | * one usable chunk at the end. |
| 593 | */ |
| 594 | |
| 595 | /* |
| 596 | * Increase size of directory if entry eats into new space. |
| 597 | * This should never push the size past a new multiple of |
| 598 | * DIRBLKSIZE. |
| 599 | * |
| 600 | * N.B. - THIS IS AN ARTIFACT OF 4.2 AND SHOULD NEVER HAPPEN. |
| 601 | */ |
| 602 | if (ndp->ni_offset + ndp->ni_count > dp->i_size) |
| 603 | dp->i_size = ndp->ni_offset + ndp->ni_count; |
| 604 | /* |
| 605 | * Get the block containing the space for the new directory entry. |
| 606 | */ |
| 607 | if (error = blkatoff(dp, ndp->ni_offset, (char **)&dirbuf, &bp)) |
| 608 | return (error); |
| 609 | /* |
| 610 | * Find space for the new entry. In the simple case, the |
| 611 | * entry at offset base will have the space. If it does |
| 612 | * not, then namei arranged that compacting the region |
| 613 | * ndp->ni_offset to ndp->ni_offset+ndp->ni_count would yield the space. |
| 614 | */ |
| 615 | ep = (struct direct *)dirbuf; |
| 616 | dsize = DIRSIZ(ep); |
| 617 | spacefree = ep->d_reclen - dsize; |
| 618 | for (loc = ep->d_reclen; loc < ndp->ni_count; ) { |
| 619 | nep = (struct direct *)(dirbuf + loc); |
| 620 | if (ep->d_ino) { |
| 621 | /* trim the existing slot */ |
| 622 | ep->d_reclen = dsize; |
| 623 | ep = (struct direct *)((char *)ep + dsize); |
| 624 | } else { |
| 625 | /* overwrite; nothing there; header is ours */ |
| 626 | spacefree += dsize; |
| 627 | } |
| 628 | dsize = DIRSIZ(nep); |
| 629 | spacefree += nep->d_reclen - dsize; |
| 630 | loc += nep->d_reclen; |
| 631 | bcopy((caddr_t)nep, (caddr_t)ep, dsize); |
| 632 | } |
| 633 | /* |
| 634 | * Update the pointer fields in the previous entry (if any), |
| 635 | * copy in the new entry, and write out the block. |
| 636 | */ |
| 637 | if (ep->d_ino == 0) { |
| 638 | if (spacefree + dsize < newentrysize) |
| 639 | panic("wdir: compact1"); |
| 640 | ndp->ni_dent.d_reclen = spacefree + dsize; |
| 641 | } else { |
| 642 | if (spacefree < newentrysize) |
| 643 | panic("wdir: compact2"); |
| 644 | ndp->ni_dent.d_reclen = spacefree; |
| 645 | ep->d_reclen = dsize; |
| 646 | ep = (struct direct *)((char *)ep + dsize); |
| 647 | } |
| 648 | bcopy((caddr_t)&ndp->ni_dent, (caddr_t)ep, (u_int)newentrysize); |
| 649 | error = bwrite(bp); |
| 650 | dp->i_flag |= IUPD|ICHG; |
| 651 | if (!error && ndp->ni_endoff && ndp->ni_endoff < dp->i_size) |
| 652 | error = itrunc(dp, (u_long)ndp->ni_endoff, IO_SYNC); |
| 653 | return (error); |
| 654 | } |
| 655 | |
| 656 | /* |
| 657 | * Remove a directory entry after a call to namei, using |
| 658 | * the parameters which it left in nameidata. The entry |
| 659 | * ni_offset contains the offset into the directory of the |
| 660 | * entry to be eliminated. The ni_count field contains the |
| 661 | * size of the previous record in the directory. If this |
| 662 | * is 0, the first entry is being deleted, so we need only |
| 663 | * zero the inode number to mark the entry as free. If the |
| 664 | * entry isn't the first in the directory, we must reclaim |
| 665 | * the space of the now empty record by adding the record size |
| 666 | * to the size of the previous entry. |
| 667 | */ |
| 668 | dirremove(ndp) |
| 669 | register struct nameidata *ndp; |
| 670 | { |
| 671 | register struct inode *dp = VTOI(ndp->ni_dvp); |
| 672 | struct direct *ep; |
| 673 | struct buf *bp; |
| 674 | int error; |
| 675 | |
| 676 | if (ndp->ni_count == 0) { |
| 677 | /* |
| 678 | * First entry in block: set d_ino to zero. |
| 679 | */ |
| 680 | ndp->ni_dent.d_ino = 0; |
| 681 | ndp->ni_count = ndp->ni_resid = DIRSIZ(&ndp->ni_dent); |
| 682 | ndp->ni_base = (caddr_t)&ndp->ni_dent; |
| 683 | ndp->ni_iov = &ndp->ni_nd.nd_iovec; |
| 684 | ndp->ni_iovcnt = 1; |
| 685 | ndp->ni_rw = UIO_WRITE; |
| 686 | ndp->ni_uioseg = UIO_SYSSPACE; |
| 687 | error = |
| 688 | ufs_write(ndp->ni_dvp, &ndp->ni_uio, IO_SYNC, ndp->ni_cred); |
| 689 | } else { |
| 690 | /* |
| 691 | * Collapse new free space into previous entry. |
| 692 | */ |
| 693 | if (error = blkatoff(dp, ndp->ni_offset - ndp->ni_count, |
| 694 | (char **)&ep, &bp)) { |
| 695 | return (error); |
| 696 | } |
| 697 | ep->d_reclen += ndp->ni_dent.d_reclen; |
| 698 | error = bwrite(bp); |
| 699 | dp->i_flag |= IUPD|ICHG; |
| 700 | } |
| 701 | return (error); |
| 702 | } |
| 703 | |
| 704 | /* |
| 705 | * Rewrite an existing directory entry to point at the inode |
| 706 | * supplied. The parameters describing the directory entry are |
| 707 | * set up by a call to namei. |
| 708 | */ |
| 709 | dirrewrite(dp, ip, ndp) |
| 710 | struct inode *dp, *ip; |
| 711 | struct nameidata *ndp; |
| 712 | { |
| 713 | |
| 714 | ndp->ni_dent.d_ino = ip->i_number; |
| 715 | ndp->ni_count = ndp->ni_resid = DIRSIZ(&ndp->ni_dent); |
| 716 | ndp->ni_base = (caddr_t)&ndp->ni_dent; |
| 717 | ndp->ni_iov = &ndp->ni_nd.nd_iovec; |
| 718 | ndp->ni_iovcnt = 1; |
| 719 | ndp->ni_rw = UIO_WRITE; |
| 720 | ndp->ni_uioseg = UIO_SYSSPACE; |
| 721 | return (ufs_write(ITOV(dp), &ndp->ni_uio, IO_SYNC, ndp->ni_cred)); |
| 722 | } |
| 723 | |
| 724 | /* |
| 725 | * Return buffer with contents of block "offset" |
| 726 | * from the beginning of directory "ip". If "res" |
| 727 | * is non-zero, fill it in with a pointer to the |
| 728 | * remaining space in the directory. |
| 729 | */ |
| 730 | blkatoff(ip, offset, res, bpp) |
| 731 | struct inode *ip; |
| 732 | off_t offset; |
| 733 | char **res; |
| 734 | struct buf **bpp; |
| 735 | { |
| 736 | register struct fs *fs = ip->i_fs; |
| 737 | daddr_t lbn = lblkno(fs, offset); |
| 738 | int bsize = blksize(fs, ip, lbn); |
| 739 | struct buf *bp; |
| 740 | daddr_t bn; |
| 741 | int error; |
| 742 | |
| 743 | *bpp = 0; |
| 744 | if (error = bread(ITOV(ip), lbn, bsize, NOCRED, &bp)) { |
| 745 | brelse(bp); |
| 746 | return (error); |
| 747 | } |
| 748 | if (res) |
| 749 | *res = bp->b_un.b_addr + blkoff(fs, offset); |
| 750 | *bpp = bp; |
| 751 | return (0); |
| 752 | } |
| 753 | |
| 754 | /* |
| 755 | * Check if a directory is empty or not. |
| 756 | * Inode supplied must be locked. |
| 757 | * |
| 758 | * Using a struct dirtemplate here is not precisely |
| 759 | * what we want, but better than using a struct direct. |
| 760 | * |
| 761 | * NB: does not handle corrupted directories. |
| 762 | */ |
| 763 | dirempty(ip, parentino, cred) |
| 764 | register struct inode *ip; |
| 765 | ino_t parentino; |
| 766 | struct ucred *cred; |
| 767 | { |
| 768 | register off_t off; |
| 769 | struct dirtemplate dbuf; |
| 770 | register struct direct *dp = (struct direct *)&dbuf; |
| 771 | int error, count; |
| 772 | #define MINDIRSIZ (sizeof (struct dirtemplate) / 2) |
| 773 | |
| 774 | for (off = 0; off < ip->i_size; off += dp->d_reclen) { |
| 775 | error = vn_rdwr(UIO_READ, ITOV(ip), (caddr_t)dp, MINDIRSIZ, off, |
| 776 | UIO_SYSSPACE, IO_NODELOCKED, cred, &count, (struct proc *)0); |
| 777 | /* |
| 778 | * Since we read MINDIRSIZ, residual must |
| 779 | * be 0 unless we're at end of file. |
| 780 | */ |
| 781 | if (error || count != 0) |
| 782 | return (0); |
| 783 | /* avoid infinite loops */ |
| 784 | if (dp->d_reclen == 0) |
| 785 | return (0); |
| 786 | /* skip empty entries */ |
| 787 | if (dp->d_ino == 0) |
| 788 | continue; |
| 789 | /* accept only "." and ".." */ |
| 790 | if (dp->d_namlen > 2) |
| 791 | return (0); |
| 792 | if (dp->d_name[0] != '.') |
| 793 | return (0); |
| 794 | /* |
| 795 | * At this point d_namlen must be 1 or 2. |
| 796 | * 1 implies ".", 2 implies ".." if second |
| 797 | * char is also "." |
| 798 | */ |
| 799 | if (dp->d_namlen == 1) |
| 800 | continue; |
| 801 | if (dp->d_name[1] == '.' && dp->d_ino == parentino) |
| 802 | continue; |
| 803 | return (0); |
| 804 | } |
| 805 | return (1); |
| 806 | } |
| 807 | |
| 808 | /* |
| 809 | * Check if source directory is in the path of the target directory. |
| 810 | * Target is supplied locked, source is unlocked. |
| 811 | * The target is always iput() before returning. |
| 812 | */ |
| 813 | checkpath(source, target, cred) |
| 814 | struct inode *source, *target; |
| 815 | struct ucred *cred; |
| 816 | { |
| 817 | struct dirtemplate dirbuf; |
| 818 | struct inode *ip; |
| 819 | int error = 0; |
| 820 | |
| 821 | ip = target; |
| 822 | if (ip->i_number == source->i_number) { |
| 823 | error = EEXIST; |
| 824 | goto out; |
| 825 | } |
| 826 | if (ip->i_number == ROOTINO) |
| 827 | goto out; |
| 828 | |
| 829 | for (;;) { |
| 830 | if ((ip->i_mode&IFMT) != IFDIR) { |
| 831 | error = ENOTDIR; |
| 832 | break; |
| 833 | } |
| 834 | error = vn_rdwr(UIO_READ, ITOV(ip), (caddr_t)&dirbuf, |
| 835 | sizeof (struct dirtemplate), (off_t)0, UIO_SYSSPACE, |
| 836 | IO_NODELOCKED, cred, (int *)0, (struct proc *)0); |
| 837 | if (error != 0) |
| 838 | break; |
| 839 | if (dirbuf.dotdot_namlen != 2 || |
| 840 | dirbuf.dotdot_name[0] != '.' || |
| 841 | dirbuf.dotdot_name[1] != '.') { |
| 842 | error = ENOTDIR; |
| 843 | break; |
| 844 | } |
| 845 | if (dirbuf.dotdot_ino == source->i_number) { |
| 846 | error = EINVAL; |
| 847 | break; |
| 848 | } |
| 849 | if (dirbuf.dotdot_ino == ROOTINO) |
| 850 | break; |
| 851 | iput(ip); |
| 852 | if (error = iget(ip, dirbuf.dotdot_ino, &ip)) |
| 853 | break; |
| 854 | } |
| 855 | |
| 856 | out: |
| 857 | if (error == ENOTDIR) |
| 858 | printf("checkpath: .. not a directory\n"); |
| 859 | if (ip != NULL) |
| 860 | iput(ip); |
| 861 | return (error); |
| 862 | } |