| 1 | /* vfs_lookup.c 6.2 83/09/09 */ |
| 2 | |
| 3 | #include "../h/param.h" |
| 4 | #include "../h/systm.h" |
| 5 | #include "../h/inode.h" |
| 6 | #include "../h/fs.h" |
| 7 | #include "../h/mount.h" |
| 8 | #include "../h/dir.h" |
| 9 | #include "../h/user.h" |
| 10 | #include "../h/buf.h" |
| 11 | #include "../h/conf.h" |
| 12 | #include "../h/uio.h" |
| 13 | #include "../h/nami.h" |
| 14 | |
| 15 | struct buf *blkatoff(); |
| 16 | int dirchk = 0; |
| 17 | /* |
| 18 | * Convert a pathname into a pointer to a locked inode, |
| 19 | * with side effects usable in creating and removing files. |
| 20 | * This is a very central and rather complicated routine. |
| 21 | * |
| 22 | * The func argument gives the routine which returns successive |
| 23 | * characters of the name to be translated. |
| 24 | * |
| 25 | * The flag argument is (LOOKUP, CREATE, DELETE) depending on whether |
| 26 | * the name is to be (looked up, created, deleted). If flag has |
| 27 | * LOCKPARENT or'ed into it and the target of the pathname exists, |
| 28 | * namei returns both the target and its parent directory locked. |
| 29 | * If the file system is not maintained in a strict tree hierarchy, |
| 30 | * this can result in a deadlock situation. When creating and |
| 31 | * LOCKPARENT is specified, the target may not be ".". When deleting |
| 32 | * and LOCKPARENT is specified, the target may be ".", but the caller |
| 33 | * must check to insure it does an irele and iput instead of two iputs. |
| 34 | * |
| 35 | * The follow argument is 1 when symbolic links are to be followed |
| 36 | * when they occur at the end of the name translation process. |
| 37 | * |
| 38 | * Overall outline: |
| 39 | * |
| 40 | * copy in name |
| 41 | * get starting directory |
| 42 | * dirloop: |
| 43 | * check accessibility of directory |
| 44 | * dirloop2: |
| 45 | * copy next component of name to u.u_dent |
| 46 | * handle degenerate case where name is null string |
| 47 | * search for name in directory, to found or notfound |
| 48 | * notfound: |
| 49 | * if creating, return locked directory, leaving info on avail. slots |
| 50 | * else return error |
| 51 | * found: |
| 52 | * if at end of path and deleting, return information to allow delete |
| 53 | * if at end of path and rewriting (create and LOCKPARENT), lock targe |
| 54 | * inode and return info to allow rewrite |
| 55 | * if .. and on mounted filesys, look in mount table for parent |
| 56 | * if symbolic link, massage name in buffer and continue at dirloop |
| 57 | * if more components of name, do next level at dirloop |
| 58 | * return the answer as locked inode |
| 59 | * |
| 60 | * NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode, |
| 61 | * but unlocked. |
| 62 | */ |
| 63 | struct inode * |
| 64 | namei(func, flag, follow) |
| 65 | int (*func)(), flag, follow; |
| 66 | { |
| 67 | register char *cp; /* pointer into pathname argument */ |
| 68 | /* these variables refer to things which must be freed or unlocked */ |
| 69 | register struct inode *dp = 0; /* the directory we are searching */ |
| 70 | register struct fs *fs; /* file system that directory is in */ |
| 71 | register struct buf *bp = 0; /* a buffer of directory entries */ |
| 72 | register struct direct *ep; /* the current directory entry */ |
| 73 | int entryoffsetinblock; /* offset of ep in bp's buffer */ |
| 74 | register struct buf *nbp; /* buffer storing path name argument */ |
| 75 | /* these variables hold information about the search for a slot */ |
| 76 | enum {NONE, COMPACT, FOUND} slotstatus; |
| 77 | int slotoffset = -1; /* offset of area with free space */ |
| 78 | int slotsize; /* size of area at slotoffset */ |
| 79 | int slotfreespace; /* amount of space free in slot */ |
| 80 | int slotneeded; /* size of the entry we're seeking */ |
| 81 | /* */ |
| 82 | int dirsize; |
| 83 | int prevoff; /* u.u_offset of previous entry */ |
| 84 | int nlink = 0; /* number of symbolic links taken */ |
| 85 | struct inode *pdp; /* saved dp during symlink work */ |
| 86 | int i; |
| 87 | int lockparent; |
| 88 | |
| 89 | lockparent = flag & LOCKPARENT; |
| 90 | flag &= ~LOCKPARENT; |
| 91 | /* |
| 92 | * Get a buffer for the name to be translated, and copy the |
| 93 | * name into the buffer. |
| 94 | */ |
| 95 | nbp = geteblk(MAXPATHLEN); |
| 96 | for (cp = nbp->b_un.b_addr; *cp = (*func)(); ) { |
| 97 | if ((*cp&0377) == ('/'|0200) || (*cp&0200) && flag != 2) { |
| 98 | u.u_error = EPERM; |
| 99 | goto bad; |
| 100 | } |
| 101 | cp++; |
| 102 | if (cp >= nbp->b_un.b_addr + MAXPATHLEN) { |
| 103 | u.u_error = ENOENT; |
| 104 | goto bad; |
| 105 | } |
| 106 | } |
| 107 | if (u.u_error) |
| 108 | goto bad; |
| 109 | |
| 110 | /* |
| 111 | * Get starting directory. |
| 112 | */ |
| 113 | cp = nbp->b_un.b_addr; |
| 114 | if (*cp == '/') { |
| 115 | while (*cp == '/') |
| 116 | cp++; |
| 117 | if ((dp = u.u_rdir) == NULL) |
| 118 | dp = rootdir; |
| 119 | } else |
| 120 | dp = u.u_cdir; |
| 121 | fs = dp->i_fs; |
| 122 | ilock(dp); |
| 123 | dp->i_count++; |
| 124 | u.u_pdir = (struct inode *)0xc0000000; /* illegal */ |
| 125 | |
| 126 | /* |
| 127 | * We come to dirloop to search a new directory. |
| 128 | * The directory must be locked so that it can be |
| 129 | * iput, and fs must be already set to dp->i_fs. |
| 130 | */ |
| 131 | dirloop: |
| 132 | /* |
| 133 | * Check accessiblity of directory. |
| 134 | */ |
| 135 | if ((dp->i_mode&IFMT) != IFDIR) { |
| 136 | u.u_error = ENOTDIR; |
| 137 | goto bad; |
| 138 | } |
| 139 | if (access(dp, IEXEC)) |
| 140 | goto bad; |
| 141 | |
| 142 | dirloop2: |
| 143 | /* |
| 144 | * Copy next component of name to u.u_dent. |
| 145 | */ |
| 146 | for (i = 0; *cp != 0 && *cp != '/'; cp++) { |
| 147 | if (i >= MAXNAMLEN) { |
| 148 | u.u_error = ENOENT; |
| 149 | goto bad; |
| 150 | } |
| 151 | u.u_dent.d_name[i++] = *cp; |
| 152 | } |
| 153 | u.u_dent.d_namlen = i; |
| 154 | u.u_dent.d_name[i] = 0; |
| 155 | |
| 156 | /* |
| 157 | * Check for degenerate name (e.g. / or "") |
| 158 | * which is a way of talking about a directory, |
| 159 | * e.g. like "/." or ".". |
| 160 | */ |
| 161 | if (u.u_dent.d_name[0] == 0) { |
| 162 | if (flag || lockparent) { |
| 163 | u.u_error = EISDIR; |
| 164 | goto bad; |
| 165 | } |
| 166 | brelse(nbp); |
| 167 | return (dp); |
| 168 | } |
| 169 | |
| 170 | /* |
| 171 | * Suppress search for slots unless creating |
| 172 | * file and at end of pathname, in which case |
| 173 | * we watch for a place to put the new file in |
| 174 | * case it doesn't already exist. |
| 175 | */ |
| 176 | slotstatus = FOUND; |
| 177 | if (flag == CREATE && *cp == 0) { |
| 178 | slotstatus = NONE; |
| 179 | slotfreespace = 0; |
| 180 | slotneeded = DIRSIZ(&u.u_dent); |
| 181 | } |
| 182 | |
| 183 | dirsize = roundup(dp->i_size, DIRBLKSIZ); |
| 184 | u.u_offset = 0; |
| 185 | while (u.u_offset < dirsize) { |
| 186 | /* |
| 187 | * If offset is on a block boundary, |
| 188 | * read the next directory block. |
| 189 | * Release previous if it exists. |
| 190 | */ |
| 191 | if (blkoff(fs, u.u_offset) == 0) { |
| 192 | if (bp != NULL) |
| 193 | brelse(bp); |
| 194 | bp = blkatoff(dp, u.u_offset, (char **)0); |
| 195 | if (bp == 0) |
| 196 | goto bad; |
| 197 | entryoffsetinblock = 0; |
| 198 | } |
| 199 | |
| 200 | /* |
| 201 | * If still looking for a slot, and at a DIRBLKSIZE |
| 202 | * boundary, have to start looking for free space |
| 203 | * again. |
| 204 | */ |
| 205 | if (slotstatus == NONE && |
| 206 | (entryoffsetinblock&(DIRBLKSIZ-1)) == 0) { |
| 207 | slotoffset = -1; |
| 208 | slotfreespace = 0; |
| 209 | } |
| 210 | |
| 211 | /* |
| 212 | * Get pointer to next entry, and do consistency checking: |
| 213 | * record length must be multiple of 4 |
| 214 | * record length must not be zero |
| 215 | * entry must fit in rest of this DIRBLKSIZ block |
| 216 | * record must be large enough to contain name |
| 217 | * When dirchk is set we also check: |
| 218 | * name is not longer than MAXNAMLEN |
| 219 | * name must be as long as advertised, and null terminated |
| 220 | * Checking last two conditions is done only when dirchk is |
| 221 | * set, to save time. |
| 222 | */ |
| 223 | ep = (struct direct *)(bp->b_un.b_addr + entryoffsetinblock); |
| 224 | i = DIRBLKSIZ - (entryoffsetinblock & (DIRBLKSIZ - 1)); |
| 225 | if ((ep->d_reclen & 0x3) || ep->d_reclen == 0 || |
| 226 | ep->d_reclen > i || DIRSIZ(ep) > ep->d_reclen || |
| 227 | dirchk && (ep->d_namlen > MAXNAMLEN || dirbadname(ep))) { |
| 228 | dirbad(dp, "mangled entry"); |
| 229 | u.u_offset += i; |
| 230 | entryoffsetinblock += i; |
| 231 | continue; |
| 232 | } |
| 233 | |
| 234 | /* |
| 235 | * If an appropriate sized slot has not yet been found, |
| 236 | * check to see if one is available. Also accumulate space |
| 237 | * in the current block so that we can determine if |
| 238 | * compaction is viable. |
| 239 | */ |
| 240 | if (slotstatus != FOUND) { |
| 241 | int size = ep->d_reclen; |
| 242 | |
| 243 | if (ep->d_ino != 0) |
| 244 | size -= DIRSIZ(ep); |
| 245 | if (size > 0) { |
| 246 | if (size >= slotneeded) { |
| 247 | slotstatus = FOUND; |
| 248 | slotoffset = u.u_offset; |
| 249 | slotsize = ep->d_reclen; |
| 250 | } else if (slotstatus == NONE) { |
| 251 | slotfreespace += size; |
| 252 | if (slotoffset == -1) |
| 253 | slotoffset = u.u_offset; |
| 254 | if (slotfreespace >= slotneeded) { |
| 255 | slotstatus = COMPACT; |
| 256 | slotsize = |
| 257 | u.u_offset+ep->d_reclen - |
| 258 | slotoffset; |
| 259 | } |
| 260 | } |
| 261 | } |
| 262 | } |
| 263 | |
| 264 | /* |
| 265 | * Check for a name match. |
| 266 | */ |
| 267 | if (ep->d_ino) { |
| 268 | if (ep->d_namlen == u.u_dent.d_namlen && |
| 269 | !bcmp(u.u_dent.d_name, ep->d_name, ep->d_namlen)) |
| 270 | goto found; |
| 271 | } |
| 272 | prevoff = u.u_offset; |
| 273 | u.u_offset += ep->d_reclen; |
| 274 | entryoffsetinblock += ep->d_reclen; |
| 275 | } |
| 276 | /* notfound: */ |
| 277 | /* |
| 278 | * If creating, and at end of pathname and current |
| 279 | * directory has not been removed, then can consider |
| 280 | * allowing file to be created. |
| 281 | */ |
| 282 | if (flag == CREATE && *cp == 0 && dp->i_nlink != 0) { |
| 283 | /* |
| 284 | * Access for write is interpreted as allowing |
| 285 | * creation of files in the directory. |
| 286 | */ |
| 287 | if (access(dp, IWRITE)) |
| 288 | goto bad; |
| 289 | /* |
| 290 | * Return an indication of where the new directory |
| 291 | * entry should be put. If we didn't find a slot, |
| 292 | * then set u.u_count to 0 indicating that the |
| 293 | * new slot belongs at the end of the directory. |
| 294 | * If we found a slot, then the new entry can be |
| 295 | * put in the range [u.u_offset..u.u_offset+u.u_count) |
| 296 | */ |
| 297 | if (slotstatus == NONE) |
| 298 | u.u_count = 0; |
| 299 | else { |
| 300 | u.u_offset = slotoffset; |
| 301 | u.u_count = slotsize; |
| 302 | } |
| 303 | dp->i_flag |= IUPD|ICHG; |
| 304 | if (bp) |
| 305 | brelse(bp); |
| 306 | brelse(nbp); |
| 307 | /* |
| 308 | * We return with the directory locked, so that |
| 309 | * the parameters we set up above will still be |
| 310 | * valid if we actually decide to do a direnter(). |
| 311 | * We return NULL to indicate that the entry doesn't |
| 312 | * currently exist, leaving a pointer to the (locked) |
| 313 | * directory inode in u.u_pdir. |
| 314 | */ |
| 315 | u.u_pdir = dp; |
| 316 | return (NULL); |
| 317 | } |
| 318 | u.u_error = ENOENT; |
| 319 | goto bad; |
| 320 | found: |
| 321 | /* |
| 322 | * Check that directory length properly reflects presence |
| 323 | * of this entry. |
| 324 | */ |
| 325 | if (entryoffsetinblock + DIRSIZ(ep) > dp->i_size) { |
| 326 | dirbad(dp, "i_size too small"); |
| 327 | dp->i_size = entryoffsetinblock + DIRSIZ(ep); |
| 328 | dp->i_flag |= IUPD|ICHG; |
| 329 | } |
| 330 | |
| 331 | /* |
| 332 | * Found component in pathname; save directory |
| 333 | * entry in u.u_dent, and release directory buffer. |
| 334 | */ |
| 335 | bcopy((caddr_t)ep, (caddr_t)&u.u_dent, (u_int)DIRSIZ(ep)); |
| 336 | brelse(bp); |
| 337 | bp = NULL; |
| 338 | |
| 339 | /* |
| 340 | * If deleting, and at end of pathname, return |
| 341 | * parameters which can be used to remove file. |
| 342 | * If the lockparent flag isn't set, we return only |
| 343 | * the directory (in u.u_pdir), otherwise we go |
| 344 | * on and lock the inode, being careful with ".". |
| 345 | */ |
| 346 | if (flag == DELETE && *cp == 0) { |
| 347 | /* |
| 348 | * Write access to directory required to delete files. |
| 349 | */ |
| 350 | if (access(dp, IWRITE)) |
| 351 | goto bad; |
| 352 | u.u_pdir = dp; /* for dirremove() */ |
| 353 | /* |
| 354 | * Return pointer to current entry in u.u_offset, |
| 355 | * and distance past previous entry (if there |
| 356 | * is a previous entry in this block) in u.u_count. |
| 357 | * Save directory inode pointer in u.u_pdir for dirremove(). |
| 358 | */ |
| 359 | if ((u.u_offset&(DIRBLKSIZ-1)) == 0) |
| 360 | u.u_count = 0; |
| 361 | else |
| 362 | u.u_count = u.u_offset - prevoff; |
| 363 | if (lockparent) { |
| 364 | if (dp->i_number == u.u_dent.d_ino) |
| 365 | dp->i_count++; |
| 366 | else { |
| 367 | dp = iget(dp->i_dev, fs, u.u_dent.d_ino); |
| 368 | if (dp == NULL) { |
| 369 | iput(u.u_pdir); |
| 370 | goto bad; |
| 371 | } |
| 372 | } |
| 373 | } |
| 374 | brelse(nbp); |
| 375 | return (dp); |
| 376 | } |
| 377 | |
| 378 | /* |
| 379 | * Special handling for ".." allowing chdir out of mounted |
| 380 | * file system: indirect .. in root inode to reevaluate |
| 381 | * in directory file system was mounted on. |
| 382 | */ |
| 383 | if (u.u_dent.d_name[0] == '.' && u.u_dent.d_name[1] == '.' && |
| 384 | u.u_dent.d_name[2] == '\0') { |
| 385 | if (dp == u.u_rdir) |
| 386 | u.u_dent.d_ino = dp->i_number; |
| 387 | else if (u.u_dent.d_ino == ROOTINO && |
| 388 | dp->i_number == ROOTINO) { |
| 389 | for (i = 1; i < NMOUNT; i++) |
| 390 | if (mount[i].m_bufp != NULL && |
| 391 | mount[i].m_dev == dp->i_dev) { |
| 392 | iput(dp); |
| 393 | dp = mount[i].m_inodp; |
| 394 | ilock(dp); |
| 395 | dp->i_count++; |
| 396 | fs = dp->i_fs; |
| 397 | cp -= 2; /* back over .. */ |
| 398 | goto dirloop2; |
| 399 | } |
| 400 | } |
| 401 | } |
| 402 | |
| 403 | /* |
| 404 | * If rewriting (rename), return the inode and the |
| 405 | * information required to rewrite the present directory |
| 406 | * Must get inode of directory entry to verify it's a |
| 407 | * regular file, or empty directory. |
| 408 | */ |
| 409 | if ((flag == CREATE && lockparent) && *cp == 0) { |
| 410 | if (access(dp, IWRITE)) |
| 411 | goto bad; |
| 412 | u.u_pdir = dp; /* for dirrewrite() */ |
| 413 | /* |
| 414 | * Careful about locking second inode. |
| 415 | * This can only occur if the target is ".". |
| 416 | */ |
| 417 | if (dp->i_number == u.u_dent.d_ino) { |
| 418 | u.u_error = EISDIR; /* XXX */ |
| 419 | goto bad; |
| 420 | } |
| 421 | dp = iget(dp->i_dev, fs, u.u_dent.d_ino); |
| 422 | if (dp == NULL) { |
| 423 | iput(u.u_pdir); |
| 424 | goto bad; |
| 425 | } |
| 426 | brelse(nbp); |
| 427 | return (dp); |
| 428 | } |
| 429 | |
| 430 | /* |
| 431 | * Check for symbolic link, which may require us to massage the |
| 432 | * name before we continue translation. We do not `iput' the |
| 433 | * directory because we may need it again if the symbolic link |
| 434 | * is relative to the current directory. Instead we save it |
| 435 | * unlocked as "pdp". We must get the target inode before unlocking |
| 436 | * the directory to insure that the inode will not be removed |
| 437 | * before we get it. We prevent deadlock by always fetching |
| 438 | * inodes from the root, moving down the directory tree. Thus |
| 439 | * when following backward pointers ".." we must unlock the |
| 440 | * parent directory before getting the requested directory. |
| 441 | * There is a potential race condition here if both the current |
| 442 | * and parent directories are removed before the `iget' for the |
| 443 | * inode associated with ".." returns. We hope that this occurs |
| 444 | * infrequently since we cannot avoid this race condition without |
| 445 | * implementing a sophisticated deadlock detection algorithm. |
| 446 | * Note also that this simple deadlock detection scheme will not |
| 447 | * work if the file system has any hard links other than ".." |
| 448 | * that point backwards in the directory structure. |
| 449 | */ |
| 450 | pdp = dp; |
| 451 | if (bcmp(u.u_dent.d_name, "..", 3) == 0) { |
| 452 | iunlock(pdp); /* race to get the inode */ |
| 453 | dp = iget(dp->i_dev, fs, u.u_dent.d_ino); |
| 454 | if (dp == NULL) |
| 455 | goto bad2; |
| 456 | } else if (dp->i_number == u.u_dent.d_ino) { |
| 457 | dp->i_count++; /* we want ourself, ie "." */ |
| 458 | } else { |
| 459 | dp = iget(dp->i_dev, fs, u.u_dent.d_ino); |
| 460 | iunlock(pdp); |
| 461 | if (dp == NULL) |
| 462 | goto bad2; |
| 463 | } |
| 464 | fs = dp->i_fs; |
| 465 | |
| 466 | /* |
| 467 | * Check for symbolic link |
| 468 | */ |
| 469 | if ((dp->i_mode & IFMT) == IFLNK && (follow || *cp == '/')) { |
| 470 | u_int pathlen = strlen(cp) + 1; |
| 471 | |
| 472 | if (dp->i_size + pathlen >= MAXPATHLEN - 1 || |
| 473 | ++nlink > MAXSYMLINKS) { |
| 474 | u.u_error = ELOOP; |
| 475 | goto bad2; |
| 476 | } |
| 477 | ovbcopy(cp, nbp->b_un.b_addr + dp->i_size, pathlen); |
| 478 | u.u_error = |
| 479 | rdwri(UIO_READ, dp, nbp->b_un.b_addr, (int)dp->i_size, |
| 480 | 0, 1, (int *)0); |
| 481 | if (u.u_error) |
| 482 | goto bad2; |
| 483 | cp = nbp->b_un.b_addr; |
| 484 | iput(dp); |
| 485 | if (*cp == '/') { |
| 486 | irele(pdp); |
| 487 | while (*cp == '/') |
| 488 | cp++; |
| 489 | if ((dp = u.u_rdir) == NULL) |
| 490 | dp = rootdir; |
| 491 | ilock(dp); |
| 492 | dp->i_count++; |
| 493 | } else { |
| 494 | dp = pdp; |
| 495 | ilock(dp); |
| 496 | } |
| 497 | fs = dp->i_fs; |
| 498 | goto dirloop; |
| 499 | } |
| 500 | |
| 501 | /* |
| 502 | * Not a symbolic link. If more pathname, |
| 503 | * continue at next component, else return. |
| 504 | */ |
| 505 | if (*cp == '/') { |
| 506 | while (*cp == '/') |
| 507 | cp++; |
| 508 | irele(pdp); |
| 509 | goto dirloop; |
| 510 | } |
| 511 | brelse(nbp); |
| 512 | if (lockparent) |
| 513 | u.u_pdir = pdp; |
| 514 | else |
| 515 | irele(pdp); |
| 516 | return (dp); |
| 517 | bad2: |
| 518 | irele(pdp); |
| 519 | bad: |
| 520 | if (bp) |
| 521 | brelse(bp); |
| 522 | if (dp) |
| 523 | iput(dp); |
| 524 | brelse(nbp); |
| 525 | return (NULL); |
| 526 | } |
| 527 | |
| 528 | dirbad(ip, how) |
| 529 | struct inode *ip; |
| 530 | char *how; |
| 531 | { |
| 532 | |
| 533 | printf("%s: bad dir ino %d at offset %d: %s\n", |
| 534 | ip->i_fs->fs_fsmnt, ip->i_number, u.u_offset, how); |
| 535 | } |
| 536 | |
| 537 | dirbadname(ep) |
| 538 | register struct direct *ep; |
| 539 | { |
| 540 | register int i; |
| 541 | |
| 542 | for (i = 0; i < ep->d_namlen; i++) |
| 543 | if (ep->d_name[i] == 0) |
| 544 | return (1); |
| 545 | return (ep->d_name[i]); |
| 546 | } |
| 547 | |
| 548 | /* |
| 549 | * Write a directory entry after a call to namei, using the parameters |
| 550 | * which it left in the u. area. The argument ip is the inode which |
| 551 | * the new directory entry will refer to. The u. area field u.u_pdir is |
| 552 | * a pointer to the directory to be written, which was left locked by |
| 553 | * namei. Remaining parameters (u.u_offset, u.u_count) indicate |
| 554 | * how the space for the new entry is to be gotten. |
| 555 | */ |
| 556 | direnter(ip) |
| 557 | struct inode *ip; |
| 558 | { |
| 559 | register struct direct *ep, *nep; |
| 560 | struct buf *bp; |
| 561 | int loc, spacefree, error = 0; |
| 562 | u_int dsize; |
| 563 | int newentrysize; |
| 564 | char *dirbuf; |
| 565 | |
| 566 | u.u_dent.d_ino = ip->i_number; |
| 567 | u.u_segflg = 1; |
| 568 | newentrysize = DIRSIZ(&u.u_dent); |
| 569 | if (u.u_count == 0) { |
| 570 | /* |
| 571 | * If u.u_count is 0, then namei could find no space in the |
| 572 | * directory. In this case u.u_offset will be on a directory |
| 573 | * block boundary and we will write the new entry into a fresh |
| 574 | * block. |
| 575 | */ |
| 576 | if (u.u_offset&(DIRBLKSIZ-1)) |
| 577 | panic("wdir: newblk"); |
| 578 | u.u_dent.d_reclen = DIRBLKSIZ; |
| 579 | error = rdwri(UIO_WRITE, u.u_pdir, (caddr_t)&u.u_dent, |
| 580 | newentrysize, u.u_offset, 1, (int *)0); |
| 581 | iput(u.u_pdir); |
| 582 | return (error); |
| 583 | } |
| 584 | |
| 585 | /* |
| 586 | * If u.u_count is non-zero, then namei found space for the |
| 587 | * new entry in the range u.u_offset to u.u_offset+u.u_count. |
| 588 | * in the directory. To use this space, we may have to compact |
| 589 | * the entries located there, by copying them together towards |
| 590 | * the beginning of the block, leaving the free space in |
| 591 | * one usable chunk at the end. |
| 592 | */ |
| 593 | |
| 594 | /* |
| 595 | * Increase size of directory if entry eats into new space. |
| 596 | * This should never push the size past a new multiple of |
| 597 | * DIRBLKSIZE. |
| 598 | */ |
| 599 | if (u.u_offset + u.u_count > u.u_pdir->i_size) |
| 600 | u.u_pdir->i_size = u.u_offset + u.u_count; |
| 601 | |
| 602 | /* |
| 603 | * Get the block containing the space for the new directory |
| 604 | * entry. Should return error by result instead of u.u_error. |
| 605 | */ |
| 606 | bp = blkatoff(u.u_pdir, u.u_offset, (char **)&dirbuf); |
| 607 | if (bp == 0) { |
| 608 | iput(u.u_pdir); |
| 609 | return (u.u_error); |
| 610 | } |
| 611 | |
| 612 | /* |
| 613 | * Find space for the new entry. In the simple case, the |
| 614 | * entry at offset base will have the space. If it does |
| 615 | * not, then namei arranged that compacting the region |
| 616 | * u.u_offset to u.u_offset+u.u_count would yield the space. |
| 617 | */ |
| 618 | ep = (struct direct *)dirbuf; |
| 619 | dsize = DIRSIZ(ep); |
| 620 | spacefree = ep->d_reclen - dsize; |
| 621 | for (loc = ep->d_reclen; loc < u.u_count; ) { |
| 622 | nep = (struct direct *)(dirbuf + loc); |
| 623 | if (ep->d_ino) { |
| 624 | /* trim the existing slot */ |
| 625 | ep->d_reclen = dsize; |
| 626 | ep = (struct direct *)((char *)ep + dsize); |
| 627 | } else { |
| 628 | /* overwrite; nothing there; header is ours */ |
| 629 | spacefree += dsize; |
| 630 | } |
| 631 | dsize = DIRSIZ(nep); |
| 632 | spacefree += nep->d_reclen - dsize; |
| 633 | loc += nep->d_reclen; |
| 634 | bcopy((caddr_t)nep, (caddr_t)ep, dsize); |
| 635 | } |
| 636 | /* |
| 637 | * Update the pointer fields in the previous entry (if any), |
| 638 | * copy in the new entry, and write out the block. |
| 639 | */ |
| 640 | if (ep->d_ino == 0) { |
| 641 | if (spacefree + dsize < newentrysize) |
| 642 | panic("wdir: compact1"); |
| 643 | u.u_dent.d_reclen = spacefree + dsize; |
| 644 | } else { |
| 645 | if (spacefree < newentrysize) |
| 646 | panic("wdir: compact2"); |
| 647 | u.u_dent.d_reclen = spacefree; |
| 648 | ep->d_reclen = dsize; |
| 649 | ep = (struct direct *)((char *)ep + dsize); |
| 650 | } |
| 651 | bcopy((caddr_t)&u.u_dent, (caddr_t)ep, (u_int)newentrysize); |
| 652 | bwrite(bp); |
| 653 | u.u_pdir->i_flag |= IUPD|ICHG; |
| 654 | iput(u.u_pdir); |
| 655 | return (error); |
| 656 | } |
| 657 | |
| 658 | /* |
| 659 | * Remove a directory entry after a call to namei, using the |
| 660 | * parameters which it left in the u. area. The u. entry |
| 661 | * u_offset contains the offset into the directory of the |
| 662 | * entry to be eliminated. The u_count field contains the |
| 663 | * size of the previous record in the directory. If this |
| 664 | * is 0, the first entry is being deleted, so we need only |
| 665 | * zero the inode number to mark the entry as free. If the |
| 666 | * entry isn't the first in the directory, we must reclaim |
| 667 | * the space of the now empty record by adding the record size |
| 668 | * to the size of the previous entry. |
| 669 | */ |
| 670 | dirremove() |
| 671 | { |
| 672 | register struct inode *dp = u.u_pdir; |
| 673 | register struct buf *bp; |
| 674 | struct direct *ep; |
| 675 | |
| 676 | if (u.u_count == 0) { |
| 677 | /* |
| 678 | * First entry in block: set d_ino to zero. |
| 679 | */ |
| 680 | u.u_dent.d_ino = 0; |
| 681 | (void) rdwri(UIO_WRITE, dp, (caddr_t)&u.u_dent, |
| 682 | (int)DIRSIZ(&u.u_dent), u.u_offset, 1, (int *)0); |
| 683 | } else { |
| 684 | /* |
| 685 | * Collapse new free space into previous entry. |
| 686 | */ |
| 687 | bp = blkatoff(dp, (int)(u.u_offset - u.u_count), (char **)&ep); |
| 688 | if (bp == 0) |
| 689 | return (0); |
| 690 | ep->d_reclen += u.u_dent.d_reclen; |
| 691 | bwrite(bp); |
| 692 | dp->i_flag |= IUPD|ICHG; |
| 693 | } |
| 694 | return (1); |
| 695 | } |
| 696 | |
| 697 | /* |
| 698 | * Rewrite an existing directory entry to point at the inode |
| 699 | * supplied. The parameters describing the directory entry are |
| 700 | * set up by a call to namei. |
| 701 | */ |
| 702 | dirrewrite(dp, ip) |
| 703 | struct inode *dp, *ip; |
| 704 | { |
| 705 | |
| 706 | u.u_dent.d_ino = ip->i_number; |
| 707 | u.u_error = rdwri(UIO_WRITE, dp, (caddr_t)&u.u_dent, |
| 708 | (int)DIRSIZ(&u.u_dent), u.u_offset, 1, (int *)0); |
| 709 | iput(dp); |
| 710 | } |
| 711 | |
| 712 | /* |
| 713 | * Return buffer with contents of block "offset" |
| 714 | * from the beginning of directory "ip". If "res" |
| 715 | * is non-zero, fill it in with a pointer to the |
| 716 | * remaining space in the directory. |
| 717 | */ |
| 718 | struct buf * |
| 719 | blkatoff(ip, offset, res) |
| 720 | struct inode *ip; |
| 721 | off_t offset; |
| 722 | char **res; |
| 723 | { |
| 724 | register struct fs *fs = ip->i_fs; |
| 725 | daddr_t lbn = lblkno(fs, offset); |
| 726 | int base = blkoff(fs, offset); |
| 727 | int bsize = blksize(fs, ip, lbn); |
| 728 | daddr_t bn = fsbtodb(fs, bmap(ip, lbn, B_WRITE, base, bsize)); |
| 729 | register struct buf *bp; |
| 730 | |
| 731 | if (u.u_error) |
| 732 | return (0); |
| 733 | bp = bread(ip->i_dev, bn, bsize); |
| 734 | if (bp->b_flags & B_ERROR) { |
| 735 | brelse(bp); |
| 736 | return (0); |
| 737 | } |
| 738 | if (res) |
| 739 | *res = bp->b_un.b_addr + base; |
| 740 | return (bp); |
| 741 | } |
| 742 | |
| 743 | /* |
| 744 | * Check if a directory is empty or not. |
| 745 | * Inode supplied must be locked. |
| 746 | * |
| 747 | * Using a struct dirtemplate here is not precisely |
| 748 | * what we want, but better than using a struct direct. |
| 749 | * |
| 750 | * NB: does not handle corrupted directories. |
| 751 | */ |
| 752 | dirempty(ip) |
| 753 | register struct inode *ip; |
| 754 | { |
| 755 | register off_t off; |
| 756 | struct dirtemplate dbuf; |
| 757 | register struct direct *dp = (struct direct *)&dbuf; |
| 758 | int error, count; |
| 759 | #define MINDIRSIZ (sizeof (struct dirtemplate) / 2) |
| 760 | |
| 761 | for (off = 0; off < ip->i_size; off += dp->d_reclen) { |
| 762 | error = rdwri(UIO_READ, ip, (caddr_t)dp, MINDIRSIZ, |
| 763 | off, 1, &count); |
| 764 | /* |
| 765 | * Since we read MINDIRSIZ, residual must |
| 766 | * be 0 unless we're at end of file. |
| 767 | */ |
| 768 | if (error || count != 0) |
| 769 | return (0); |
| 770 | /* skip empty entries */ |
| 771 | if (dp->d_ino == 0) |
| 772 | continue; |
| 773 | /* accept only "." and ".." */ |
| 774 | if (dp->d_namlen > 2) |
| 775 | return (0); |
| 776 | if (dp->d_name[0] != '.') |
| 777 | return (0); |
| 778 | /* |
| 779 | * At this point d_namlen must be 1 or 2. |
| 780 | * 1 implies ".", 2 implies ".." if second |
| 781 | * char is also "." |
| 782 | */ |
| 783 | if (dp->d_namlen == 1 || dp->d_name[1] == '.') |
| 784 | continue; |
| 785 | return (0); |
| 786 | } |
| 787 | return (1); |
| 788 | } |
| 789 | |
| 790 | /* |
| 791 | * Check if source directory is in the path of the target directory. |
| 792 | * Target is supplied locked, source is unlocked. |
| 793 | * The target is always iput() before returning. |
| 794 | */ |
| 795 | checkpath(source, target) |
| 796 | struct inode *source, *target; |
| 797 | { |
| 798 | struct dirtemplate dirbuf; |
| 799 | register struct inode *ip; |
| 800 | int error = 0; |
| 801 | |
| 802 | ip = target; |
| 803 | if (ip->i_number == source->i_number) { |
| 804 | error = EEXIST; |
| 805 | goto out; |
| 806 | } |
| 807 | if (ip->i_number == ROOTINO) |
| 808 | goto out; |
| 809 | |
| 810 | for (;;) { |
| 811 | if ((ip->i_mode&IFMT) != IFDIR) { |
| 812 | error = ENOTDIR; |
| 813 | break; |
| 814 | } |
| 815 | error = rdwri(UIO_READ, ip, (caddr_t)&dirbuf, |
| 816 | sizeof (struct dirtemplate), (off_t)0, 1, (int *)0); |
| 817 | if (error != 0) |
| 818 | break; |
| 819 | if (dirbuf.dotdot_namlen != 2 || |
| 820 | bcmp(dirbuf.dotdot_name, "..", 3) != 0) { |
| 821 | error = ENOTDIR; |
| 822 | break; |
| 823 | } |
| 824 | if (dirbuf.dotdot_ino == source->i_number) { |
| 825 | error = EINVAL; |
| 826 | break; |
| 827 | } |
| 828 | if (dirbuf.dotdot_ino == ROOTINO) |
| 829 | break; |
| 830 | iput(ip); |
| 831 | ip = iget(ip->i_dev, ip->i_fs, dirbuf.dotdot_ino); |
| 832 | if (ip == NULL) { |
| 833 | error = u.u_error; |
| 834 | break; |
| 835 | } |
| 836 | } |
| 837 | |
| 838 | out: |
| 839 | if (error == ENOTDIR) |
| 840 | printf("checkpath: .. not a directory\n"); |
| 841 | if (ip != NULL) |
| 842 | iput(ip); |
| 843 | return (error); |
| 844 | } |