| 1 | /* |
| 2 | * Copyright (c) 1982, 1986 Regents of the University of California. |
| 3 | * All rights reserved. The Berkeley software License Agreement |
| 4 | * specifies the terms and conditions for redistribution. |
| 5 | * |
| 6 | * @(#)vfs_lookup.c 7.4 (Berkeley) %G% |
| 7 | */ |
| 8 | |
| 9 | #include "param.h" |
| 10 | #include "systm.h" |
| 11 | #include "inode.h" |
| 12 | #include "fs.h" |
| 13 | #include "mount.h" |
| 14 | #include "dir.h" |
| 15 | #include "user.h" |
| 16 | #include "buf.h" |
| 17 | #include "conf.h" |
| 18 | #include "uio.h" |
| 19 | #include "kernel.h" |
| 20 | #include "malloc.h" |
| 21 | |
| 22 | struct buf *blkatoff(); |
| 23 | int dirchk = 0; |
| 24 | |
| 25 | /* |
| 26 | * Structures associated with name cacheing. |
| 27 | */ |
| 28 | #define NCHHASH 32 /* size of hash table */ |
| 29 | |
| 30 | #if ((NCHHASH)&((NCHHASH)-1)) != 0 |
| 31 | #define NHASH(h, i, d) ((unsigned)((h) + (i) + 13 * (int)(d)) % (NCHHASH)) |
| 32 | #else |
| 33 | #define NHASH(h, i, d) ((unsigned)((h) + (i) + 13 * (int)(d)) & ((NCHHASH)-1)) |
| 34 | #endif |
| 35 | |
| 36 | union nchash { |
| 37 | union nchash *nch_head[2]; |
| 38 | struct namecache *nch_chain[2]; |
| 39 | } nchash[NCHHASH]; |
| 40 | #define nch_forw nch_chain[0] |
| 41 | #define nch_back nch_chain[1] |
| 42 | |
| 43 | struct namecache *nchhead, **nchtail; /* LRU chain pointers */ |
| 44 | struct nchstats nchstats; /* cache effectiveness statistics */ |
| 45 | |
| 46 | /* |
| 47 | * Convert a pathname into a pointer to a locked inode. |
| 48 | * This is a very central and rather complicated routine. |
| 49 | * If the file system is not maintained in a strict tree hierarchy, |
| 50 | * this can result in a deadlock situation (see comments in code below). |
| 51 | * |
| 52 | * The flag argument is LOOKUP, CREATE, or DELETE depending on whether |
| 53 | * the name is to be looked up, created, or deleted. When CREATE or |
| 54 | * DELETE is specified, information usable in creating or deleteing a |
| 55 | * directory entry is also calculated. If flag has LOCKPARENT or'ed |
| 56 | * into it and the target of the pathname exists, namei returns both |
| 57 | * the target and its parent directory locked. When creating and |
| 58 | * LOCKPARENT is specified, the target may not be ".". When deleting |
| 59 | * and LOCKPARENT is specified, the target may be ".", but the caller |
| 60 | * must check to insure it does an irele and iput instead of two iputs. |
| 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 | * Name caching works as follows: |
| 71 | * |
| 72 | * Names found by directory scans are retained in a cache |
| 73 | * for future reference. It is managed LRU, so frequently |
| 74 | * used names will hang around. Cache is indexed by hash value |
| 75 | * obtained from (ino,dev,name) where ino & dev refer to the |
| 76 | * directory containing name. |
| 77 | * |
| 78 | * For simplicity (and economy of storage), names longer than |
| 79 | * a maximum length of NCHNAMLEN are not cached; they occur |
| 80 | * infrequently in any case, and are almost never of interest. |
| 81 | * |
| 82 | * Upon reaching the last segment of a path, if the reference |
| 83 | * is for DELETE, or NOCACHE is set (rewrite), and the |
| 84 | * name is located in the cache, it will be dropped. |
| 85 | * |
| 86 | * Overall outline of namei: |
| 87 | * |
| 88 | * copy in name |
| 89 | * get starting directory |
| 90 | * dirloop: |
| 91 | * check accessibility of directory |
| 92 | * dirloop2: |
| 93 | * copy next component of name to ndp->ni_dent |
| 94 | * handle degenerate case where name is null string |
| 95 | * look for name in cache, if found, then if at end of path |
| 96 | * and deleting or creating, drop it, else to haveino |
| 97 | * search for name in directory, to found or notfound |
| 98 | * notfound: |
| 99 | * if creating, return locked directory, leaving info on avail. slots |
| 100 | * else return error |
| 101 | * found: |
| 102 | * if at end of path and deleting, return information to allow delete |
| 103 | * if at end of path and rewriting (CREATE and LOCKPARENT), lock target |
| 104 | * inode and return info to allow rewrite |
| 105 | * if .. and on mounted filesys, look in mount table for parent |
| 106 | * if not at end, add name to cache; if at end and neither creating |
| 107 | * nor deleting, add name to cache |
| 108 | * haveino: |
| 109 | * if symbolic link, massage name in buffer and continue at dirloop |
| 110 | * if more components of name, do next level at dirloop |
| 111 | * return the answer as locked inode |
| 112 | * |
| 113 | * NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode, |
| 114 | * but unlocked. |
| 115 | */ |
| 116 | struct inode * |
| 117 | namei(ndp) |
| 118 | register struct nameidata *ndp; |
| 119 | { |
| 120 | register char *cp; /* pointer into pathname argument */ |
| 121 | /* these variables refer to things which must be freed or unlocked */ |
| 122 | register struct inode *dp = 0; /* the directory we are searching */ |
| 123 | register struct namecache *ncp; /* cache slot for entry */ |
| 124 | register struct fs *fs; /* file system that directory is in */ |
| 125 | register struct buf *bp = 0; /* a buffer of directory entries */ |
| 126 | register struct direct *ep; /* the current directory entry */ |
| 127 | int entryoffsetinblock; /* offset of ep in bp's buffer */ |
| 128 | register caddr_t nbp; /* buffer storing path name argument */ |
| 129 | /* these variables hold information about the search for a slot */ |
| 130 | enum {NONE, COMPACT, FOUND} slotstatus; |
| 131 | int slotoffset = -1; /* offset of area with free space */ |
| 132 | int slotsize; /* size of area at slotoffset */ |
| 133 | int slotfreespace; /* amount of space free in slot */ |
| 134 | int slotneeded; /* size of the entry we're seeking */ |
| 135 | /* */ |
| 136 | int numdirpasses; /* strategy for directory search */ |
| 137 | int endsearch; /* offset to end directory search */ |
| 138 | int prevoff; /* ndp->ni_offset of previous entry */ |
| 139 | int nlink = 0; /* number of symbolic links taken */ |
| 140 | struct inode *pdp; /* saved dp during symlink work */ |
| 141 | int error, i; |
| 142 | int lockparent; |
| 143 | int docache; /* == 0 do not cache last component */ |
| 144 | int makeentry; /* != 0 if name to be added to cache */ |
| 145 | unsigned hash; /* value of name hash for entry */ |
| 146 | union nchash *nhp; /* cache chain head for entry */ |
| 147 | int isdotdot; /* != 0 if current name is ".." */ |
| 148 | int flag; /* op ie, LOOKUP, CREATE, or DELETE */ |
| 149 | off_t enduseful; /* pointer past last used dir slot */ |
| 150 | |
| 151 | lockparent = ndp->ni_nameiop & LOCKPARENT; |
| 152 | docache = (ndp->ni_nameiop & NOCACHE) ^ NOCACHE; |
| 153 | flag = ndp->ni_nameiop &~ (LOCKPARENT|NOCACHE|FOLLOW); |
| 154 | if (flag == DELETE || lockparent) |
| 155 | docache = 0; |
| 156 | /* |
| 157 | * Get a buffer for the name to be translated, and copy the |
| 158 | * name into the buffer. |
| 159 | */ |
| 160 | MALLOC(nbp, caddr_t, MAXPATHLEN, M_NAMEI, M_WAITOK); |
| 161 | if (ndp->ni_segflg == UIO_SYSSPACE) |
| 162 | error = copystr(ndp->ni_dirp, nbp, MAXPATHLEN, (u_int *)0); |
| 163 | else |
| 164 | error = copyinstr(ndp->ni_dirp, nbp, MAXPATHLEN, (u_int *)0); |
| 165 | if (error) { |
| 166 | u.u_error = error; |
| 167 | goto bad; |
| 168 | } |
| 169 | |
| 170 | /* |
| 171 | * Get starting directory. |
| 172 | */ |
| 173 | cp = nbp; |
| 174 | if (*cp == '/') { |
| 175 | while (*cp == '/') |
| 176 | cp++; |
| 177 | if ((dp = u.u_rdir) == NULL) |
| 178 | dp = rootdir; |
| 179 | } else |
| 180 | dp = u.u_cdir; |
| 181 | fs = dp->i_fs; |
| 182 | ILOCK(dp); |
| 183 | dp->i_count++; |
| 184 | ndp->ni_pdir = (struct inode *)0xc0000000; /* illegal */ |
| 185 | ndp->ni_endoff = 0; |
| 186 | |
| 187 | /* |
| 188 | * We come to dirloop to search a new directory. |
| 189 | * The directory must be locked so that it can be |
| 190 | * iput, and fs must be already set to dp->i_fs. |
| 191 | */ |
| 192 | dirloop: |
| 193 | /* |
| 194 | * Check accessiblity of directory. |
| 195 | */ |
| 196 | if ((dp->i_mode&IFMT) != IFDIR) { |
| 197 | u.u_error = ENOTDIR; |
| 198 | goto bad; |
| 199 | } |
| 200 | if (access(dp, IEXEC)) |
| 201 | goto bad; |
| 202 | |
| 203 | dirloop2: |
| 204 | /* |
| 205 | * Copy next component of name to ndp->ni_dent. |
| 206 | */ |
| 207 | hash = 0; |
| 208 | for (i = 0; *cp != 0 && *cp != '/'; cp++) { |
| 209 | if (i >= MAXNAMLEN) { |
| 210 | u.u_error = ENAMETOOLONG; |
| 211 | goto bad; |
| 212 | } |
| 213 | if (*cp & 0200) |
| 214 | if ((*cp&0377) == ('/'|0200) || flag != DELETE) { |
| 215 | u.u_error = EINVAL; |
| 216 | goto bad; |
| 217 | } |
| 218 | ndp->ni_dent.d_name[i++] = *cp; |
| 219 | hash += (unsigned char)*cp * i; |
| 220 | } |
| 221 | ndp->ni_dent.d_namlen = i; |
| 222 | ndp->ni_dent.d_name[i] = '\0'; |
| 223 | isdotdot = (i == 2 && |
| 224 | ndp->ni_dent.d_name[0] == '.' && ndp->ni_dent.d_name[1] == '.'); |
| 225 | makeentry = 1; |
| 226 | if (*cp == '\0' && docache == 0) |
| 227 | makeentry = 0; |
| 228 | |
| 229 | /* |
| 230 | * Check for degenerate name (e.g. / or "") |
| 231 | * which is a way of talking about a directory, |
| 232 | * e.g. like "/." or ".". |
| 233 | */ |
| 234 | if (ndp->ni_dent.d_name[0] == '\0') { |
| 235 | if (flag != LOOKUP || lockparent) { |
| 236 | u.u_error = EISDIR; |
| 237 | goto bad; |
| 238 | } |
| 239 | FREE(nbp, M_NAMEI); |
| 240 | return (dp); |
| 241 | } |
| 242 | |
| 243 | /* |
| 244 | * We now have a segment name to search for, and a directory to search. |
| 245 | * |
| 246 | * Before tediously performing a linear scan of the directory, |
| 247 | * check the name cache to see if the directory/name pair |
| 248 | * we are looking for is known already. We don't do this |
| 249 | * if the segment name is long, simply so the cache can avoid |
| 250 | * holding long names (which would either waste space, or |
| 251 | * add greatly to the complexity). |
| 252 | */ |
| 253 | if (ndp->ni_dent.d_namlen > NCHNAMLEN) { |
| 254 | nchstats.ncs_long++; |
| 255 | makeentry = 0; |
| 256 | } else { |
| 257 | nhp = &nchash[NHASH(hash, dp->i_number, dp->i_dev)]; |
| 258 | for (ncp = nhp->nch_forw; ncp != (struct namecache *)nhp; |
| 259 | ncp = ncp->nc_forw) { |
| 260 | if (ncp->nc_ino == dp->i_number && |
| 261 | ncp->nc_dev == dp->i_dev && |
| 262 | ncp->nc_nlen == ndp->ni_dent.d_namlen && |
| 263 | !bcmp(ncp->nc_name, ndp->ni_dent.d_name, |
| 264 | (unsigned)ncp->nc_nlen)) |
| 265 | break; |
| 266 | } |
| 267 | if (ncp == (struct namecache *)nhp) { |
| 268 | nchstats.ncs_miss++; |
| 269 | ncp = NULL; |
| 270 | } else { |
| 271 | if (ncp->nc_id != ncp->nc_ip->i_id) |
| 272 | nchstats.ncs_falsehits++; |
| 273 | else if (!makeentry) |
| 274 | nchstats.ncs_badhits++; |
| 275 | else { |
| 276 | /* |
| 277 | * move this slot to end of LRU |
| 278 | * chain, if not already there |
| 279 | */ |
| 280 | if (ncp->nc_nxt) { |
| 281 | /* remove from LRU chain */ |
| 282 | *ncp->nc_prev = ncp->nc_nxt; |
| 283 | ncp->nc_nxt->nc_prev = ncp->nc_prev; |
| 284 | |
| 285 | /* and replace at end of it */ |
| 286 | ncp->nc_nxt = NULL; |
| 287 | ncp->nc_prev = nchtail; |
| 288 | *nchtail = ncp; |
| 289 | nchtail = &ncp->nc_nxt; |
| 290 | } |
| 291 | |
| 292 | /* |
| 293 | * Get the next inode in the path. |
| 294 | * See comment above other `IUNLOCK' code for |
| 295 | * an explaination of the locking protocol. |
| 296 | */ |
| 297 | pdp = dp; |
| 298 | if (!isdotdot || dp != u.u_rdir) |
| 299 | dp = ncp->nc_ip; |
| 300 | if (dp == NULL) |
| 301 | panic("namei: null cache ino"); |
| 302 | if (pdp == dp) |
| 303 | dp->i_count++; |
| 304 | else if (isdotdot) { |
| 305 | IUNLOCK(pdp); |
| 306 | igrab(dp); |
| 307 | } else { |
| 308 | igrab(dp); |
| 309 | IUNLOCK(pdp); |
| 310 | } |
| 311 | |
| 312 | /* |
| 313 | * Verify that the inode that we got |
| 314 | * did not change while we were waiting |
| 315 | * for it to be locked. |
| 316 | */ |
| 317 | if (ncp->nc_id != ncp->nc_ip->i_id) { |
| 318 | iput(dp); |
| 319 | ILOCK(pdp); |
| 320 | dp = pdp; |
| 321 | nchstats.ncs_falsehits++; |
| 322 | } else { |
| 323 | ndp->ni_dent.d_ino = dp->i_number; |
| 324 | /* ni_dent.d_reclen is garbage ... */ |
| 325 | nchstats.ncs_goodhits++; |
| 326 | goto haveino; |
| 327 | } |
| 328 | } |
| 329 | |
| 330 | /* |
| 331 | * Last component and we are renaming or deleting, |
| 332 | * the cache entry is invalid, or otherwise don't |
| 333 | * want cache entry to exist. |
| 334 | */ |
| 335 | /* remove from LRU chain */ |
| 336 | *ncp->nc_prev = ncp->nc_nxt; |
| 337 | if (ncp->nc_nxt) |
| 338 | ncp->nc_nxt->nc_prev = ncp->nc_prev; |
| 339 | else |
| 340 | nchtail = ncp->nc_prev; |
| 341 | remque(ncp); /* remove from hash chain */ |
| 342 | /* insert at head of LRU list (first to grab) */ |
| 343 | ncp->nc_nxt = nchhead; |
| 344 | ncp->nc_prev = &nchhead; |
| 345 | nchhead->nc_prev = &ncp->nc_nxt; |
| 346 | nchhead = ncp; |
| 347 | /* and make a dummy hash chain */ |
| 348 | ncp->nc_forw = ncp; |
| 349 | ncp->nc_back = ncp; |
| 350 | ncp = NULL; |
| 351 | } |
| 352 | } |
| 353 | |
| 354 | /* |
| 355 | * Suppress search for slots unless creating |
| 356 | * file and at end of pathname, in which case |
| 357 | * we watch for a place to put the new file in |
| 358 | * case it doesn't already exist. |
| 359 | */ |
| 360 | slotstatus = FOUND; |
| 361 | if (flag == CREATE && *cp == 0) { |
| 362 | slotstatus = NONE; |
| 363 | slotfreespace = 0; |
| 364 | slotneeded = DIRSIZ(&ndp->ni_dent); |
| 365 | } |
| 366 | /* |
| 367 | * If this is the same directory that this process |
| 368 | * previously searched, pick up where we last left off. |
| 369 | * We cache only lookups as these are the most common |
| 370 | * and have the greatest payoff. Caching CREATE has little |
| 371 | * benefit as it usually must search the entire directory |
| 372 | * to determine that the entry does not exist. Caching the |
| 373 | * location of the last DELETE has not reduced profiling time |
| 374 | * and hence has been removed in the interest of simplicity. |
| 375 | */ |
| 376 | if (flag != LOOKUP || dp->i_number != u.u_ncache.nc_inumber || |
| 377 | dp->i_dev != u.u_ncache.nc_dev) { |
| 378 | ndp->ni_offset = 0; |
| 379 | numdirpasses = 1; |
| 380 | } else { |
| 381 | if (u.u_ncache.nc_prevoffset > dp->i_size) |
| 382 | u.u_ncache.nc_prevoffset = 0; |
| 383 | ndp->ni_offset = u.u_ncache.nc_prevoffset; |
| 384 | entryoffsetinblock = blkoff(fs, ndp->ni_offset); |
| 385 | if (entryoffsetinblock != 0) { |
| 386 | bp = blkatoff(dp, ndp->ni_offset, (char **)0); |
| 387 | if (bp == 0) |
| 388 | goto bad; |
| 389 | } |
| 390 | numdirpasses = 2; |
| 391 | nchstats.ncs_2passes++; |
| 392 | } |
| 393 | endsearch = roundup(dp->i_size, DIRBLKSIZ); |
| 394 | enduseful = 0; |
| 395 | |
| 396 | searchloop: |
| 397 | while (ndp->ni_offset < endsearch) { |
| 398 | /* |
| 399 | * If offset is on a block boundary, |
| 400 | * read the next directory block. |
| 401 | * Release previous if it exists. |
| 402 | */ |
| 403 | if (blkoff(fs, ndp->ni_offset) == 0) { |
| 404 | if (bp != NULL) |
| 405 | brelse(bp); |
| 406 | bp = blkatoff(dp, ndp->ni_offset, (char **)0); |
| 407 | if (bp == 0) |
| 408 | goto bad; |
| 409 | entryoffsetinblock = 0; |
| 410 | } |
| 411 | /* |
| 412 | * If still looking for a slot, and at a DIRBLKSIZE |
| 413 | * boundary, have to start looking for free space again. |
| 414 | */ |
| 415 | if (slotstatus == NONE && |
| 416 | (entryoffsetinblock&(DIRBLKSIZ-1)) == 0) { |
| 417 | slotoffset = -1; |
| 418 | slotfreespace = 0; |
| 419 | } |
| 420 | /* |
| 421 | * Get pointer to next entry. |
| 422 | * Full validation checks are slow, so we only check |
| 423 | * enough to insure forward progress through the |
| 424 | * directory. Complete checks can be run by patching |
| 425 | * "dirchk" to be true. |
| 426 | */ |
| 427 | ep = (struct direct *)(bp->b_un.b_addr + entryoffsetinblock); |
| 428 | if (ep->d_reclen == 0 || |
| 429 | dirchk && dirbadentry(ep, entryoffsetinblock)) { |
| 430 | dirbad(dp, ndp->ni_offset, "mangled entry"); |
| 431 | i = DIRBLKSIZ - (entryoffsetinblock & (DIRBLKSIZ - 1)); |
| 432 | ndp->ni_offset += i; |
| 433 | entryoffsetinblock += i; |
| 434 | continue; |
| 435 | } |
| 436 | |
| 437 | /* |
| 438 | * If an appropriate sized slot has not yet been found, |
| 439 | * check to see if one is available. Also accumulate space |
| 440 | * in the current block so that we can determine if |
| 441 | * compaction is viable. |
| 442 | */ |
| 443 | if (slotstatus != FOUND) { |
| 444 | int size = ep->d_reclen; |
| 445 | |
| 446 | if (ep->d_ino != 0) |
| 447 | size -= DIRSIZ(ep); |
| 448 | if (size > 0) { |
| 449 | if (size >= slotneeded) { |
| 450 | slotstatus = FOUND; |
| 451 | slotoffset = ndp->ni_offset; |
| 452 | slotsize = ep->d_reclen; |
| 453 | } else if (slotstatus == NONE) { |
| 454 | slotfreespace += size; |
| 455 | if (slotoffset == -1) |
| 456 | slotoffset = ndp->ni_offset; |
| 457 | if (slotfreespace >= slotneeded) { |
| 458 | slotstatus = COMPACT; |
| 459 | slotsize = ndp->ni_offset + |
| 460 | ep->d_reclen - slotoffset; |
| 461 | } |
| 462 | } |
| 463 | } |
| 464 | } |
| 465 | |
| 466 | /* |
| 467 | * Check for a name match. |
| 468 | */ |
| 469 | if (ep->d_ino) { |
| 470 | if (ep->d_namlen == ndp->ni_dent.d_namlen && |
| 471 | !bcmp(ndp->ni_dent.d_name, ep->d_name, |
| 472 | (unsigned)ep->d_namlen)) |
| 473 | goto found; |
| 474 | } |
| 475 | prevoff = ndp->ni_offset; |
| 476 | ndp->ni_offset += ep->d_reclen; |
| 477 | entryoffsetinblock += ep->d_reclen; |
| 478 | if (ep->d_ino) |
| 479 | enduseful = ndp->ni_offset; |
| 480 | } |
| 481 | /* notfound: */ |
| 482 | /* |
| 483 | * If we started in the middle of the directory and failed |
| 484 | * to find our target, we must check the beginning as well. |
| 485 | */ |
| 486 | if (numdirpasses == 2) { |
| 487 | numdirpasses--; |
| 488 | ndp->ni_offset = 0; |
| 489 | endsearch = u.u_ncache.nc_prevoffset; |
| 490 | goto searchloop; |
| 491 | } |
| 492 | /* |
| 493 | * If creating, and at end of pathname and current |
| 494 | * directory has not been removed, then can consider |
| 495 | * allowing file to be created. |
| 496 | */ |
| 497 | if (flag == CREATE && *cp == 0 && dp->i_nlink != 0) { |
| 498 | /* |
| 499 | * Access for write is interpreted as allowing |
| 500 | * creation of files in the directory. |
| 501 | */ |
| 502 | if (access(dp, IWRITE)) |
| 503 | goto bad; |
| 504 | /* |
| 505 | * Return an indication of where the new directory |
| 506 | * entry should be put. If we didn't find a slot, |
| 507 | * then set ndp->ni_count to 0 indicating that the new |
| 508 | * slot belongs at the end of the directory. If we found |
| 509 | * a slot, then the new entry can be put in the range |
| 510 | * [ndp->ni_offset .. ndp->ni_offset + ndp->ni_count) |
| 511 | */ |
| 512 | if (slotstatus == NONE) { |
| 513 | ndp->ni_offset = roundup(dp->i_size, DIRBLKSIZ); |
| 514 | ndp->ni_count = 0; |
| 515 | enduseful = ndp->ni_offset; |
| 516 | } else { |
| 517 | ndp->ni_offset = slotoffset; |
| 518 | ndp->ni_count = slotsize; |
| 519 | if (enduseful < slotoffset + slotsize) |
| 520 | enduseful = slotoffset + slotsize; |
| 521 | } |
| 522 | ndp->ni_endoff = roundup(enduseful, DIRBLKSIZ); |
| 523 | dp->i_flag |= IUPD|ICHG; |
| 524 | if (bp) |
| 525 | brelse(bp); |
| 526 | FREE(nbp, M_NAMEI); |
| 527 | /* |
| 528 | * We return with the directory locked, so that |
| 529 | * the parameters we set up above will still be |
| 530 | * valid if we actually decide to do a direnter(). |
| 531 | * We return NULL to indicate that the entry doesn't |
| 532 | * currently exist, leaving a pointer to the (locked) |
| 533 | * directory inode in ndp->ni_pdir. |
| 534 | */ |
| 535 | ndp->ni_pdir = dp; |
| 536 | return (NULL); |
| 537 | } |
| 538 | u.u_error = ENOENT; |
| 539 | goto bad; |
| 540 | found: |
| 541 | if (numdirpasses == 2) |
| 542 | nchstats.ncs_pass2++; |
| 543 | /* |
| 544 | * Check that directory length properly reflects presence |
| 545 | * of this entry. |
| 546 | */ |
| 547 | if (entryoffsetinblock + DIRSIZ(ep) > dp->i_size) { |
| 548 | dirbad(dp, ndp->ni_offset, "i_size too small"); |
| 549 | dp->i_size = entryoffsetinblock + DIRSIZ(ep); |
| 550 | dp->i_flag |= IUPD|ICHG; |
| 551 | } |
| 552 | |
| 553 | /* |
| 554 | * Found component in pathname. |
| 555 | * If the final component of path name, save information |
| 556 | * in the cache as to where the entry was found. |
| 557 | */ |
| 558 | if (*cp == '\0' && flag == LOOKUP) { |
| 559 | u.u_ncache.nc_prevoffset = ndp->ni_offset &~ (DIRBLKSIZ - 1); |
| 560 | u.u_ncache.nc_inumber = dp->i_number; |
| 561 | u.u_ncache.nc_dev = dp->i_dev; |
| 562 | } |
| 563 | /* |
| 564 | * Save directory entry's inode number and reclen in ndp->ni_dent, |
| 565 | * and release directory buffer. |
| 566 | */ |
| 567 | ndp->ni_dent.d_ino = ep->d_ino; |
| 568 | ndp->ni_dent.d_reclen = ep->d_reclen; |
| 569 | brelse(bp); |
| 570 | bp = NULL; |
| 571 | |
| 572 | /* |
| 573 | * If deleting, and at end of pathname, return |
| 574 | * parameters which can be used to remove file. |
| 575 | * If the lockparent flag isn't set, we return only |
| 576 | * the directory (in ndp->ni_pdir), otherwise we go |
| 577 | * on and lock the inode, being careful with ".". |
| 578 | */ |
| 579 | if (flag == DELETE && *cp == 0) { |
| 580 | /* |
| 581 | * Write access to directory required to delete files. |
| 582 | */ |
| 583 | if (access(dp, IWRITE)) |
| 584 | goto bad; |
| 585 | ndp->ni_pdir = dp; /* for dirremove() */ |
| 586 | /* |
| 587 | * Return pointer to current entry in ndp->ni_offset, |
| 588 | * and distance past previous entry (if there |
| 589 | * is a previous entry in this block) in ndp->ni_count. |
| 590 | * Save directory inode pointer in ndp->ni_pdir for dirremove(). |
| 591 | */ |
| 592 | if ((ndp->ni_offset&(DIRBLKSIZ-1)) == 0) |
| 593 | ndp->ni_count = 0; |
| 594 | else |
| 595 | ndp->ni_count = ndp->ni_offset - prevoff; |
| 596 | if (lockparent) { |
| 597 | if (dp->i_number == ndp->ni_dent.d_ino) |
| 598 | dp->i_count++; |
| 599 | else { |
| 600 | dp = iget(dp->i_dev, fs, ndp->ni_dent.d_ino); |
| 601 | if (dp == NULL) { |
| 602 | iput(ndp->ni_pdir); |
| 603 | goto bad; |
| 604 | } |
| 605 | /* |
| 606 | * If directory is "sticky", then user must own |
| 607 | * the directory, or the file in it, else he |
| 608 | * may not delete it (unless he's root). This |
| 609 | * implements append-only directories. |
| 610 | */ |
| 611 | if ((ndp->ni_pdir->i_mode & ISVTX) && |
| 612 | u.u_uid != 0 && |
| 613 | u.u_uid != ndp->ni_pdir->i_uid && |
| 614 | dp->i_uid != u.u_uid) { |
| 615 | iput(ndp->ni_pdir); |
| 616 | u.u_error = EPERM; |
| 617 | goto bad; |
| 618 | } |
| 619 | } |
| 620 | } |
| 621 | FREE(nbp, M_NAMEI); |
| 622 | return (dp); |
| 623 | } |
| 624 | |
| 625 | /* |
| 626 | * Special handling for ".." allowing chdir out of mounted |
| 627 | * file system: indirect .. in root inode to reevaluate |
| 628 | * in directory file system was mounted on. |
| 629 | */ |
| 630 | if (isdotdot) { |
| 631 | if (dp == u.u_rdir) { |
| 632 | ndp->ni_dent.d_ino = dp->i_number; |
| 633 | makeentry = 0; |
| 634 | } else if (ndp->ni_dent.d_ino == ROOTINO && |
| 635 | dp->i_number == ROOTINO) { |
| 636 | for (i = 1; i < NMOUNT; i++) |
| 637 | if (mount[i].m_fs != NULL && |
| 638 | mount[i].m_dev == dp->i_dev) { |
| 639 | iput(dp); |
| 640 | dp = mount[i].m_inodp; |
| 641 | ILOCK(dp); |
| 642 | dp->i_count++; |
| 643 | fs = dp->i_fs; |
| 644 | cp -= 2; /* back over .. */ |
| 645 | goto dirloop2; |
| 646 | } |
| 647 | } |
| 648 | } |
| 649 | |
| 650 | /* |
| 651 | * If rewriting (rename), return the inode and the |
| 652 | * information required to rewrite the present directory |
| 653 | * Must get inode of directory entry to verify it's a |
| 654 | * regular file, or empty directory. |
| 655 | */ |
| 656 | if ((flag == CREATE && lockparent) && *cp == 0) { |
| 657 | if (access(dp, IWRITE)) |
| 658 | goto bad; |
| 659 | ndp->ni_pdir = dp; /* for dirrewrite() */ |
| 660 | /* |
| 661 | * Careful about locking second inode. |
| 662 | * This can only occur if the target is ".". |
| 663 | */ |
| 664 | if (dp->i_number == ndp->ni_dent.d_ino) { |
| 665 | u.u_error = EISDIR; /* XXX */ |
| 666 | goto bad; |
| 667 | } |
| 668 | dp = iget(dp->i_dev, fs, ndp->ni_dent.d_ino); |
| 669 | if (dp == NULL) { |
| 670 | iput(ndp->ni_pdir); |
| 671 | goto bad; |
| 672 | } |
| 673 | FREE(nbp, M_NAMEI); |
| 674 | return (dp); |
| 675 | } |
| 676 | |
| 677 | /* |
| 678 | * Check for symbolic link, which may require us to massage the |
| 679 | * name before we continue translation. We do not `iput' the |
| 680 | * directory because we may need it again if the symbolic link |
| 681 | * is relative to the current directory. Instead we save it |
| 682 | * unlocked as "pdp". We must get the target inode before unlocking |
| 683 | * the directory to insure that the inode will not be removed |
| 684 | * before we get it. We prevent deadlock by always fetching |
| 685 | * inodes from the root, moving down the directory tree. Thus |
| 686 | * when following backward pointers ".." we must unlock the |
| 687 | * parent directory before getting the requested directory. |
| 688 | * There is a potential race condition here if both the current |
| 689 | * and parent directories are removed before the `iget' for the |
| 690 | * inode associated with ".." returns. We hope that this occurs |
| 691 | * infrequently since we cannot avoid this race condition without |
| 692 | * implementing a sophisticated deadlock detection algorithm. |
| 693 | * Note also that this simple deadlock detection scheme will not |
| 694 | * work if the file system has any hard links other than ".." |
| 695 | * that point backwards in the directory structure. |
| 696 | */ |
| 697 | pdp = dp; |
| 698 | if (isdotdot) { |
| 699 | IUNLOCK(pdp); /* race to get the inode */ |
| 700 | dp = iget(dp->i_dev, fs, ndp->ni_dent.d_ino); |
| 701 | if (dp == NULL) |
| 702 | goto bad2; |
| 703 | } else if (dp->i_number == ndp->ni_dent.d_ino) { |
| 704 | dp->i_count++; /* we want ourself, ie "." */ |
| 705 | } else { |
| 706 | dp = iget(dp->i_dev, fs, ndp->ni_dent.d_ino); |
| 707 | IUNLOCK(pdp); |
| 708 | if (dp == NULL) |
| 709 | goto bad2; |
| 710 | } |
| 711 | |
| 712 | /* |
| 713 | * Insert name into cache if appropriate. |
| 714 | */ |
| 715 | if (makeentry) { |
| 716 | if (ncp != NULL) |
| 717 | panic("namei: duplicating cache"); |
| 718 | /* |
| 719 | * Free the cache slot at head of lru chain. |
| 720 | */ |
| 721 | if (ncp = nchhead) { |
| 722 | /* remove from lru chain */ |
| 723 | *ncp->nc_prev = ncp->nc_nxt; |
| 724 | if (ncp->nc_nxt) |
| 725 | ncp->nc_nxt->nc_prev = ncp->nc_prev; |
| 726 | else |
| 727 | nchtail = ncp->nc_prev; |
| 728 | remque(ncp); /* remove from old hash chain */ |
| 729 | /* grab the inode we just found */ |
| 730 | ncp->nc_ip = dp; |
| 731 | /* fill in cache info */ |
| 732 | ncp->nc_ino = pdp->i_number; /* parents inum */ |
| 733 | ncp->nc_dev = pdp->i_dev; /* & device */ |
| 734 | ncp->nc_idev = dp->i_dev; /* our device */ |
| 735 | ncp->nc_id = dp->i_id; /* identifier */ |
| 736 | ncp->nc_nlen = ndp->ni_dent.d_namlen; |
| 737 | bcopy(ndp->ni_dent.d_name, ncp->nc_name, |
| 738 | (unsigned)ncp->nc_nlen); |
| 739 | /* link at end of lru chain */ |
| 740 | ncp->nc_nxt = NULL; |
| 741 | ncp->nc_prev = nchtail; |
| 742 | *nchtail = ncp; |
| 743 | nchtail = &ncp->nc_nxt; |
| 744 | /* and insert on hash chain */ |
| 745 | insque(ncp, nhp); |
| 746 | } |
| 747 | } |
| 748 | |
| 749 | haveino: |
| 750 | fs = dp->i_fs; |
| 751 | |
| 752 | /* |
| 753 | * Check for symbolic link |
| 754 | */ |
| 755 | if ((dp->i_mode & IFMT) == IFLNK && |
| 756 | ((ndp->ni_nameiop & FOLLOW) || *cp == '/')) { |
| 757 | u_int pathlen = strlen(cp) + 1; |
| 758 | |
| 759 | if (dp->i_size + pathlen >= MAXPATHLEN - 1) { |
| 760 | u.u_error = ENAMETOOLONG; |
| 761 | goto bad2; |
| 762 | } |
| 763 | if (++nlink > MAXSYMLINKS) { |
| 764 | u.u_error = ELOOP; |
| 765 | goto bad2; |
| 766 | } |
| 767 | ovbcopy(cp, nbp + dp->i_size, pathlen); |
| 768 | u.u_error = |
| 769 | rdwri(UIO_READ, dp, nbp, (int)dp->i_size, |
| 770 | (off_t)0, 1, (int *)0); |
| 771 | if (u.u_error) |
| 772 | goto bad2; |
| 773 | cp = nbp; |
| 774 | iput(dp); |
| 775 | if (*cp == '/') { |
| 776 | irele(pdp); |
| 777 | while (*cp == '/') |
| 778 | cp++; |
| 779 | if ((dp = u.u_rdir) == NULL) |
| 780 | dp = rootdir; |
| 781 | ILOCK(dp); |
| 782 | dp->i_count++; |
| 783 | } else { |
| 784 | dp = pdp; |
| 785 | ILOCK(dp); |
| 786 | } |
| 787 | fs = dp->i_fs; |
| 788 | goto dirloop; |
| 789 | } |
| 790 | |
| 791 | /* |
| 792 | * Not a symbolic link. If more pathname, |
| 793 | * continue at next component, else return. |
| 794 | */ |
| 795 | if (*cp == '/') { |
| 796 | while (*cp == '/') |
| 797 | cp++; |
| 798 | irele(pdp); |
| 799 | goto dirloop; |
| 800 | } |
| 801 | FREE(nbp, M_NAMEI); |
| 802 | if (lockparent) |
| 803 | ndp->ni_pdir = pdp; |
| 804 | else |
| 805 | irele(pdp); |
| 806 | return (dp); |
| 807 | bad2: |
| 808 | irele(pdp); |
| 809 | bad: |
| 810 | if (bp) |
| 811 | brelse(bp); |
| 812 | if (dp) |
| 813 | iput(dp); |
| 814 | FREE(nbp, M_NAMEI); |
| 815 | return (NULL); |
| 816 | } |
| 817 | |
| 818 | |
| 819 | dirbad(ip, offset, how) |
| 820 | struct inode *ip; |
| 821 | off_t offset; |
| 822 | char *how; |
| 823 | { |
| 824 | |
| 825 | printf("%s: bad dir ino %d at offset %d: %s\n", |
| 826 | ip->i_fs->fs_fsmnt, ip->i_number, offset, how); |
| 827 | } |
| 828 | |
| 829 | /* |
| 830 | * Do consistency checking on a directory entry: |
| 831 | * record length must be multiple of 4 |
| 832 | * entry must fit in rest of its DIRBLKSIZ block |
| 833 | * record must be large enough to contain entry |
| 834 | * name is not longer than MAXNAMLEN |
| 835 | * name must be as long as advertised, and null terminated |
| 836 | */ |
| 837 | dirbadentry(ep, entryoffsetinblock) |
| 838 | register struct direct *ep; |
| 839 | int entryoffsetinblock; |
| 840 | { |
| 841 | register int i; |
| 842 | |
| 843 | if ((ep->d_reclen & 0x3) != 0 || |
| 844 | ep->d_reclen > DIRBLKSIZ - (entryoffsetinblock & (DIRBLKSIZ - 1)) || |
| 845 | ep->d_reclen < DIRSIZ(ep) || ep->d_namlen > MAXNAMLEN) |
| 846 | return (1); |
| 847 | for (i = 0; i < ep->d_namlen; i++) |
| 848 | if (ep->d_name[i] == '\0') |
| 849 | return (1); |
| 850 | return (ep->d_name[i]); |
| 851 | } |
| 852 | |
| 853 | /* |
| 854 | * Write a directory entry after a call to namei, using the parameters |
| 855 | * which it left in the u. area. The argument ip is the inode which |
| 856 | * the new directory entry will refer to. The u. area field ndp->ni_pdir is |
| 857 | * a pointer to the directory to be written, which was left locked by |
| 858 | * namei. Remaining parameters (ndp->ni_offset, ndp->ni_count) indicate |
| 859 | * how the space for the new entry is to be gotten. |
| 860 | */ |
| 861 | direnter(ip, ndp) |
| 862 | struct inode *ip; |
| 863 | register struct nameidata *ndp; |
| 864 | { |
| 865 | register struct direct *ep, *nep; |
| 866 | register struct inode *dp = ndp->ni_pdir; |
| 867 | struct buf *bp; |
| 868 | int loc, spacefree, error = 0; |
| 869 | u_int dsize; |
| 870 | int newentrysize; |
| 871 | char *dirbuf; |
| 872 | |
| 873 | ndp->ni_dent.d_ino = ip->i_number; |
| 874 | newentrysize = DIRSIZ(&ndp->ni_dent); |
| 875 | if (ndp->ni_count == 0) { |
| 876 | /* |
| 877 | * If ndp->ni_count is 0, then namei could find no space in the |
| 878 | * directory. In this case ndp->ni_offset will be on a directory |
| 879 | * block boundary and we will write the new entry into a fresh |
| 880 | * block. |
| 881 | */ |
| 882 | if (ndp->ni_offset&(DIRBLKSIZ-1)) |
| 883 | panic("wdir: newblk"); |
| 884 | ndp->ni_dent.d_reclen = DIRBLKSIZ; |
| 885 | error = rdwri(UIO_WRITE, dp, (caddr_t)&ndp->ni_dent, |
| 886 | newentrysize, ndp->ni_offset, 1, (int *)0); |
| 887 | if (DIRBLKSIZ > dp->i_fs->fs_fsize) |
| 888 | panic("wdir: blksize"); /* XXX - should grow w/bmap() */ |
| 889 | else |
| 890 | dp->i_size = roundup(dp->i_size, DIRBLKSIZ); |
| 891 | iput(dp); |
| 892 | return (error); |
| 893 | } |
| 894 | |
| 895 | /* |
| 896 | * If ndp->ni_count is non-zero, then namei found space for the new |
| 897 | * entry in the range ndp->ni_offset to ndp->ni_offset + ndp->ni_count. |
| 898 | * in the directory. To use this space, we may have to compact |
| 899 | * the entries located there, by copying them together towards |
| 900 | * the beginning of the block, leaving the free space in |
| 901 | * one usable chunk at the end. |
| 902 | */ |
| 903 | |
| 904 | /* |
| 905 | * Increase size of directory if entry eats into new space. |
| 906 | * This should never push the size past a new multiple of |
| 907 | * DIRBLKSIZE. |
| 908 | * |
| 909 | * N.B. - THIS IS AN ARTIFACT OF 4.2 AND SHOULD NEVER HAPPEN. |
| 910 | */ |
| 911 | if (ndp->ni_offset + ndp->ni_count > dp->i_size) |
| 912 | dp->i_size = ndp->ni_offset + ndp->ni_count; |
| 913 | /* |
| 914 | * Get the block containing the space for the new directory |
| 915 | * entry. Should return error by result instead of u.u_error. |
| 916 | */ |
| 917 | bp = blkatoff(dp, ndp->ni_offset, (char **)&dirbuf); |
| 918 | if (bp == 0) { |
| 919 | iput(dp); |
| 920 | return (u.u_error); |
| 921 | } |
| 922 | /* |
| 923 | * Find space for the new entry. In the simple case, the |
| 924 | * entry at offset base will have the space. If it does |
| 925 | * not, then namei arranged that compacting the region |
| 926 | * ndp->ni_offset to ndp->ni_offset+ndp->ni_count would yield the space. |
| 927 | */ |
| 928 | ep = (struct direct *)dirbuf; |
| 929 | dsize = DIRSIZ(ep); |
| 930 | spacefree = ep->d_reclen - dsize; |
| 931 | for (loc = ep->d_reclen; loc < ndp->ni_count; ) { |
| 932 | nep = (struct direct *)(dirbuf + loc); |
| 933 | if (ep->d_ino) { |
| 934 | /* trim the existing slot */ |
| 935 | ep->d_reclen = dsize; |
| 936 | ep = (struct direct *)((char *)ep + dsize); |
| 937 | } else { |
| 938 | /* overwrite; nothing there; header is ours */ |
| 939 | spacefree += dsize; |
| 940 | } |
| 941 | dsize = DIRSIZ(nep); |
| 942 | spacefree += nep->d_reclen - dsize; |
| 943 | loc += nep->d_reclen; |
| 944 | bcopy((caddr_t)nep, (caddr_t)ep, dsize); |
| 945 | } |
| 946 | /* |
| 947 | * Update the pointer fields in the previous entry (if any), |
| 948 | * copy in the new entry, and write out the block. |
| 949 | */ |
| 950 | if (ep->d_ino == 0) { |
| 951 | if (spacefree + dsize < newentrysize) |
| 952 | panic("wdir: compact1"); |
| 953 | ndp->ni_dent.d_reclen = spacefree + dsize; |
| 954 | } else { |
| 955 | if (spacefree < newentrysize) |
| 956 | panic("wdir: compact2"); |
| 957 | ndp->ni_dent.d_reclen = spacefree; |
| 958 | ep->d_reclen = dsize; |
| 959 | ep = (struct direct *)((char *)ep + dsize); |
| 960 | } |
| 961 | bcopy((caddr_t)&ndp->ni_dent, (caddr_t)ep, (u_int)newentrysize); |
| 962 | bwrite(bp); |
| 963 | dp->i_flag |= IUPD|ICHG; |
| 964 | if (ndp->ni_endoff && ndp->ni_endoff < dp->i_size) |
| 965 | itrunc(dp, (u_long)ndp->ni_endoff); |
| 966 | iput(dp); |
| 967 | return (error); |
| 968 | } |
| 969 | |
| 970 | /* |
| 971 | * Remove a directory entry after a call to namei, using the |
| 972 | * parameters which it left in the u. area. The u. entry |
| 973 | * ni_offset contains the offset into the directory of the |
| 974 | * entry to be eliminated. The ni_count field contains the |
| 975 | * size of the previous record in the directory. If this |
| 976 | * is 0, the first entry is being deleted, so we need only |
| 977 | * zero the inode number to mark the entry as free. If the |
| 978 | * entry isn't the first in the directory, we must reclaim |
| 979 | * the space of the now empty record by adding the record size |
| 980 | * to the size of the previous entry. |
| 981 | */ |
| 982 | dirremove(ndp) |
| 983 | register struct nameidata *ndp; |
| 984 | { |
| 985 | register struct inode *dp = ndp->ni_pdir; |
| 986 | register struct buf *bp; |
| 987 | struct direct *ep; |
| 988 | |
| 989 | if (ndp->ni_count == 0) { |
| 990 | /* |
| 991 | * First entry in block: set d_ino to zero. |
| 992 | */ |
| 993 | ndp->ni_dent.d_ino = 0; |
| 994 | (void) rdwri(UIO_WRITE, dp, (caddr_t)&ndp->ni_dent, |
| 995 | (int)DIRSIZ(&ndp->ni_dent), ndp->ni_offset, 1, (int *)0); |
| 996 | } else { |
| 997 | /* |
| 998 | * Collapse new free space into previous entry. |
| 999 | */ |
| 1000 | bp = blkatoff(dp, ndp->ni_offset - ndp->ni_count, (char **)&ep); |
| 1001 | if (bp == 0) |
| 1002 | return (0); |
| 1003 | ep->d_reclen += ndp->ni_dent.d_reclen; |
| 1004 | bwrite(bp); |
| 1005 | dp->i_flag |= IUPD|ICHG; |
| 1006 | } |
| 1007 | return (1); |
| 1008 | } |
| 1009 | |
| 1010 | /* |
| 1011 | * Rewrite an existing directory entry to point at the inode |
| 1012 | * supplied. The parameters describing the directory entry are |
| 1013 | * set up by a call to namei. |
| 1014 | */ |
| 1015 | dirrewrite(dp, ip, ndp) |
| 1016 | struct inode *dp, *ip; |
| 1017 | struct nameidata *ndp; |
| 1018 | { |
| 1019 | |
| 1020 | ndp->ni_dent.d_ino = ip->i_number; |
| 1021 | u.u_error = rdwri(UIO_WRITE, dp, (caddr_t)&ndp->ni_dent, |
| 1022 | (int)DIRSIZ(&ndp->ni_dent), ndp->ni_offset, 1, (int *)0); |
| 1023 | iput(dp); |
| 1024 | } |
| 1025 | |
| 1026 | /* |
| 1027 | * Return buffer with contents of block "offset" |
| 1028 | * from the beginning of directory "ip". If "res" |
| 1029 | * is non-zero, fill it in with a pointer to the |
| 1030 | * remaining space in the directory. |
| 1031 | */ |
| 1032 | struct buf * |
| 1033 | blkatoff(ip, offset, res) |
| 1034 | struct inode *ip; |
| 1035 | off_t offset; |
| 1036 | char **res; |
| 1037 | { |
| 1038 | register struct fs *fs = ip->i_fs; |
| 1039 | daddr_t lbn = lblkno(fs, offset); |
| 1040 | int bsize = blksize(fs, ip, lbn); |
| 1041 | register struct buf *bp; |
| 1042 | daddr_t bn; |
| 1043 | |
| 1044 | bn = bmap(ip, lbn, B_READ, bsize); |
| 1045 | if (u.u_error) |
| 1046 | return (0); |
| 1047 | if (bn == (daddr_t)-1) { |
| 1048 | dirbad(ip, offset, "hole in dir"); |
| 1049 | return (0); |
| 1050 | } |
| 1051 | #ifdef SECSIZE |
| 1052 | bp = bread(ip->i_dev, fsbtodb(fs, bn), bsize, fs->fs_dbsize); |
| 1053 | #else SECSIZE |
| 1054 | bp = bread(ip->i_dev, fsbtodb(fs, bn), bsize); |
| 1055 | #endif SECSIZE |
| 1056 | if (bp->b_flags & B_ERROR) { |
| 1057 | brelse(bp); |
| 1058 | return (0); |
| 1059 | } |
| 1060 | if (res) |
| 1061 | *res = bp->b_un.b_addr + blkoff(fs, offset); |
| 1062 | return (bp); |
| 1063 | } |
| 1064 | |
| 1065 | /* |
| 1066 | * Check if a directory is empty or not. |
| 1067 | * Inode supplied must be locked. |
| 1068 | * |
| 1069 | * Using a struct dirtemplate here is not precisely |
| 1070 | * what we want, but better than using a struct direct. |
| 1071 | * |
| 1072 | * NB: does not handle corrupted directories. |
| 1073 | */ |
| 1074 | dirempty(ip, parentino) |
| 1075 | register struct inode *ip; |
| 1076 | ino_t parentino; |
| 1077 | { |
| 1078 | register off_t off; |
| 1079 | struct dirtemplate dbuf; |
| 1080 | register struct direct *dp = (struct direct *)&dbuf; |
| 1081 | int error, count; |
| 1082 | #define MINDIRSIZ (sizeof (struct dirtemplate) / 2) |
| 1083 | |
| 1084 | for (off = 0; off < ip->i_size; off += dp->d_reclen) { |
| 1085 | error = rdwri(UIO_READ, ip, (caddr_t)dp, MINDIRSIZ, |
| 1086 | off, 1, &count); |
| 1087 | /* |
| 1088 | * Since we read MINDIRSIZ, residual must |
| 1089 | * be 0 unless we're at end of file. |
| 1090 | */ |
| 1091 | if (error || count != 0) |
| 1092 | return (0); |
| 1093 | /* avoid infinite loops */ |
| 1094 | if (dp->d_reclen == 0) |
| 1095 | return (0); |
| 1096 | /* skip empty entries */ |
| 1097 | if (dp->d_ino == 0) |
| 1098 | continue; |
| 1099 | /* accept only "." and ".." */ |
| 1100 | if (dp->d_namlen > 2) |
| 1101 | return (0); |
| 1102 | if (dp->d_name[0] != '.') |
| 1103 | return (0); |
| 1104 | /* |
| 1105 | * At this point d_namlen must be 1 or 2. |
| 1106 | * 1 implies ".", 2 implies ".." if second |
| 1107 | * char is also "." |
| 1108 | */ |
| 1109 | if (dp->d_namlen == 1) |
| 1110 | continue; |
| 1111 | if (dp->d_name[1] == '.' && dp->d_ino == parentino) |
| 1112 | continue; |
| 1113 | return (0); |
| 1114 | } |
| 1115 | return (1); |
| 1116 | } |
| 1117 | |
| 1118 | /* |
| 1119 | * Check if source directory is in the path of the target directory. |
| 1120 | * Target is supplied locked, source is unlocked. |
| 1121 | * The target is always iput() before returning. |
| 1122 | */ |
| 1123 | checkpath(source, target) |
| 1124 | struct inode *source, *target; |
| 1125 | { |
| 1126 | struct dirtemplate dirbuf; |
| 1127 | register struct inode *ip; |
| 1128 | int error = 0; |
| 1129 | |
| 1130 | ip = target; |
| 1131 | if (ip->i_number == source->i_number) { |
| 1132 | error = EEXIST; |
| 1133 | goto out; |
| 1134 | } |
| 1135 | if (ip->i_number == ROOTINO) |
| 1136 | goto out; |
| 1137 | |
| 1138 | for (;;) { |
| 1139 | if ((ip->i_mode&IFMT) != IFDIR) { |
| 1140 | error = ENOTDIR; |
| 1141 | break; |
| 1142 | } |
| 1143 | error = rdwri(UIO_READ, ip, (caddr_t)&dirbuf, |
| 1144 | sizeof (struct dirtemplate), (off_t)0, 1, (int *)0); |
| 1145 | if (error != 0) |
| 1146 | break; |
| 1147 | if (dirbuf.dotdot_namlen != 2 || |
| 1148 | dirbuf.dotdot_name[0] != '.' || |
| 1149 | dirbuf.dotdot_name[1] != '.') { |
| 1150 | error = ENOTDIR; |
| 1151 | break; |
| 1152 | } |
| 1153 | if (dirbuf.dotdot_ino == source->i_number) { |
| 1154 | error = EINVAL; |
| 1155 | break; |
| 1156 | } |
| 1157 | if (dirbuf.dotdot_ino == ROOTINO) |
| 1158 | break; |
| 1159 | iput(ip); |
| 1160 | ip = iget(ip->i_dev, ip->i_fs, dirbuf.dotdot_ino); |
| 1161 | if (ip == NULL) { |
| 1162 | error = u.u_error; |
| 1163 | break; |
| 1164 | } |
| 1165 | } |
| 1166 | |
| 1167 | out: |
| 1168 | if (error == ENOTDIR) |
| 1169 | printf("checkpath: .. not a directory\n"); |
| 1170 | if (ip != NULL) |
| 1171 | iput(ip); |
| 1172 | return (error); |
| 1173 | } |
| 1174 | |
| 1175 | /* |
| 1176 | * Name cache initialization, from main() when we are booting |
| 1177 | */ |
| 1178 | nchinit() |
| 1179 | { |
| 1180 | register union nchash *nchp; |
| 1181 | register struct namecache *ncp; |
| 1182 | |
| 1183 | nchhead = 0; |
| 1184 | nchtail = &nchhead; |
| 1185 | for (ncp = namecache; ncp < &namecache[nchsize]; ncp++) { |
| 1186 | ncp->nc_forw = ncp; /* hash chain */ |
| 1187 | ncp->nc_back = ncp; |
| 1188 | ncp->nc_nxt = NULL; /* lru chain */ |
| 1189 | *nchtail = ncp; |
| 1190 | ncp->nc_prev = nchtail; |
| 1191 | nchtail = &ncp->nc_nxt; |
| 1192 | /* all else is zero already */ |
| 1193 | } |
| 1194 | for (nchp = nchash; nchp < &nchash[NCHHASH]; nchp++) { |
| 1195 | nchp->nch_head[0] = nchp; |
| 1196 | nchp->nch_head[1] = nchp; |
| 1197 | } |
| 1198 | } |
| 1199 | |
| 1200 | /* |
| 1201 | * Cache flush, called when filesys is umounted to |
| 1202 | * remove entries that would now be invalid |
| 1203 | * |
| 1204 | * The line "nxtcp = nchhead" near the end is to avoid potential problems |
| 1205 | * if the cache lru chain is modified while we are dumping the |
| 1206 | * inode. This makes the algorithm O(n^2), but do you think I care? |
| 1207 | */ |
| 1208 | nchinval(dev) |
| 1209 | register dev_t dev; |
| 1210 | { |
| 1211 | register struct namecache *ncp, *nxtcp; |
| 1212 | |
| 1213 | for (ncp = nchhead; ncp; ncp = nxtcp) { |
| 1214 | nxtcp = ncp->nc_nxt; |
| 1215 | if (ncp->nc_ip == NULL || |
| 1216 | (ncp->nc_idev != dev && ncp->nc_dev != dev)) |
| 1217 | continue; |
| 1218 | /* free the resources we had */ |
| 1219 | ncp->nc_idev = NODEV; |
| 1220 | ncp->nc_dev = NODEV; |
| 1221 | ncp->nc_id = NULL; |
| 1222 | ncp->nc_ino = 0; |
| 1223 | ncp->nc_ip = NULL; |
| 1224 | remque(ncp); /* remove entry from its hash chain */ |
| 1225 | ncp->nc_forw = ncp; /* and make a dummy one */ |
| 1226 | ncp->nc_back = ncp; |
| 1227 | /* delete this entry from LRU chain */ |
| 1228 | *ncp->nc_prev = nxtcp; |
| 1229 | if (nxtcp) |
| 1230 | nxtcp->nc_prev = ncp->nc_prev; |
| 1231 | else |
| 1232 | nchtail = ncp->nc_prev; |
| 1233 | /* cause rescan of list, it may have altered */ |
| 1234 | nxtcp = nchhead; |
| 1235 | /* put the now-free entry at head of LRU */ |
| 1236 | ncp->nc_nxt = nxtcp; |
| 1237 | ncp->nc_prev = &nchhead; |
| 1238 | nxtcp->nc_prev = &ncp->nc_nxt; |
| 1239 | nchhead = ncp; |
| 1240 | } |
| 1241 | } |
| 1242 | |
| 1243 | /* |
| 1244 | * Name cache invalidation of all entries. |
| 1245 | */ |
| 1246 | cacheinvalall() |
| 1247 | { |
| 1248 | register struct namecache *ncp; |
| 1249 | |
| 1250 | for (ncp = namecache; ncp < &namecache[nchsize]; ncp++) |
| 1251 | ncp->nc_id = 0; |
| 1252 | } |