1 /*
2 * linux/fs/sysv/namei.c
3 *
4 * minix/namei.c
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 *
7 * coh/namei.c
8 * Copyright (C) 1993 Pascal Haible, Bruno Haible
9 *
10 * sysv/namei.c
11 * Copyright (C) 1993 Bruno Haible
12 * Copyright (C) 1997, 1998 Krzysztof G. Baranowski
13 */
14
15
16 #include <linux/sched.h>
17 #include <linux/kernel.h>
18 #include <linux/fs.h>
19 #include <linux/sysv_fs.h>
20 #include <linux/string.h>
21 #include <linux/stat.h>
22 #include <linux/errno.h>
23
24 /* compare strings: name[0..len-1] (not zero-terminated) and
25 * buffer[0..] (filled with zeroes up to buffer[0..maxlen-1])
26 */
27 static inline int namecompare(int len, int maxlen,
28 const char * name, const char * buffer)
29 {
30 if (len > maxlen)
31 return 0;
32 if (len < maxlen && buffer[len])
33 return 0;
34 return !memcmp(name, buffer, len);
35 }
36
37 /*
38 * ok, we cannot use strncmp, as the name is not in our data space. [Now it is!]
39 * Thus we'll have to use sysv_match. No big problem. Match also makes
40 * some sanity tests.
41 *
42 * NOTE! unlike strncmp, sysv_match returns 1 for success, 0 for failure.
43 */
44 static int sysv_match(int len, const char * name, struct sysv_dir_entry * de)
45 {
46 if (!de->inode || len > SYSV_NAMELEN)
47 return 0;
48 /* "" means "." ---> so paths like "/usr/lib//libc.a" work */
49 if (!len && (de->name[0]=='.') && (de->name[1]=='\0'))
50 return 1;
51 return namecompare(len, SYSV_NAMELEN, name, de->name);
52 }
53
54 /*
55 * sysv_find_entry()
56 *
57 * finds an entry in the specified directory with the wanted name. It
58 * returns the cache buffer in which the entry was found, and the entry
59 * itself (as a parameter - res_dir). It does NOT read the inode of the
60 * entry - you'll have to do that yourself if you want to.
61 */
62 static struct buffer_head * sysv_find_entry(struct inode * dir,
63 const char * name, int namelen, struct sysv_dir_entry ** res_dir)
64 {
65 struct super_block * sb;
66 unsigned long pos, block, offset; /* pos = block * block_size + offset */
67 struct buffer_head * bh;
68
69 *res_dir = NULL;
70 sb = dir->i_sb;
71 if (namelen > SYSV_NAMELEN) {
72 if (sb->sv_truncate)
73 namelen = SYSV_NAMELEN;
74 else
75 return NULL;
76 }
77 bh = NULL;
78 pos = block = offset = 0;
79 while (pos < dir->i_size) {
80 if (!bh) {
81 bh = sysv_file_bread(dir, block, 0);
82 if (!bh) {
83 /* offset = 0; */ block++;
84 pos += sb->sv_block_size;
85 continue;
86 }
87 }
88 if (sysv_match(namelen, name,
89 *res_dir = (struct sysv_dir_entry *) (bh->b_data + offset) ))
90 return bh;
91 pos += SYSV_DIRSIZE;
92 offset += SYSV_DIRSIZE;
93 if (offset < sb->sv_block_size)
94 continue;
95 brelse(bh);
96 bh = NULL;
97 offset = 0; block++;
98 }
99 brelse(bh);
100 *res_dir = NULL;
101 return NULL;
102 }
103
104 static struct dentry *sysv_lookup(struct inode * dir, struct dentry * dentry)
105 {
106 struct inode * inode = NULL;
107 struct sysv_dir_entry * de;
108 struct buffer_head * bh;
109
110 bh = sysv_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
111
112 if (bh) {
113 int ino = de->inode;
114 brelse(bh);
115 inode = iget(dir->i_sb, ino);
116
117 if (!inode)
118 return ERR_PTR(-EACCES);
119 }
120 d_add(dentry, inode);
121 return NULL;
122 }
123
124 /*
125 * sysv_add_entry()
126 *
127 * adds a file entry to the specified directory, returning a possible
128 * error value if it fails.
129 *
130 * NOTE!! The inode part of 'de' is left at 0 - which means you
131 * may not sleep between calling this and putting something into
132 * the entry, as someone else might have used it while you slept.
133 */
134 static int sysv_add_entry(struct inode * dir,
135 const char * name, int namelen,
136 struct buffer_head ** res_buf,
137 struct sysv_dir_entry ** res_dir)
138 {
139 struct super_block * sb;
140 int i;
141 unsigned long pos, block, offset; /* pos = block * block_size + offset */
142 struct buffer_head * bh;
143 struct sysv_dir_entry * de;
144
145 *res_buf = NULL;
146 *res_dir = NULL;
147 sb = dir->i_sb;
148 if (namelen > SYSV_NAMELEN) {
149 if (sb->sv_truncate)
150 namelen = SYSV_NAMELEN;
151 else
152 return -ENAMETOOLONG;
153 }
154 if (!namelen)
155 return -ENOENT;
156 bh = NULL;
157 pos = block = offset = 0;
158 while (1) {
159 if (!bh) {
160 bh = sysv_file_bread(dir, block, 1);
161 if (!bh)
162 return -ENOSPC;
163 }
164 de = (struct sysv_dir_entry *) (bh->b_data + offset);
165 pos += SYSV_DIRSIZE;
166 offset += SYSV_DIRSIZE;
167 if (pos > dir->i_size) {
168 de->inode = 0;
169 dir->i_size = pos;
170 mark_inode_dirty(dir);
171 }
172 if (de->inode) {
173 if (namecompare(namelen, SYSV_NAMELEN, name, de->name)) {
174 brelse(bh);
175 return -EEXIST;
176 }
177 } else {
178 dir->i_mtime = dir->i_ctime = CURRENT_TIME;
179 mark_inode_dirty(dir);
180 for (i = 0; i < SYSV_NAMELEN ; i++)
181 de->name[i] = (i < namelen) ? name[i] : 0;
182 mark_buffer_dirty(bh);
183 *res_dir = de;
184 break;
185 }
186 if (offset < sb->sv_block_size)
187 continue;
188 brelse(bh);
189 bh = NULL;
190 offset = 0; block++;
191 }
192 *res_buf = bh;
193 return 0;
194 }
195
196 static int sysv_create(struct inode * dir, struct dentry * dentry, int mode)
197 {
198 int error;
199 struct inode * inode;
200 struct buffer_head * bh;
201 struct sysv_dir_entry * de;
202
203 inode = sysv_new_inode(dir);
204 if (!inode)
205 return -ENOSPC;
206 inode->i_op = &sysv_file_inode_operations;
207 inode->i_fop = &sysv_file_operations;
208 inode->i_mapping->a_ops = &sysv_aops;
209 inode->i_mode = mode;
210 mark_inode_dirty(inode);
211 error = sysv_add_entry(dir, dentry->d_name.name,
212 dentry->d_name.len, &bh, &de);
213 if (error) {
214 inode->i_nlink--;
215 mark_inode_dirty(inode);
216 iput(inode);
217 return error;
218 }
219 de->inode = inode->i_ino;
220 mark_buffer_dirty(bh);
221 brelse(bh);
222 d_instantiate(dentry, inode);
223 return 0;
224 }
225
226 static int sysv_mknod(struct inode * dir, struct dentry * dentry, int mode, int rdev)
227 {
228 int error;
229 struct inode * inode;
230 struct buffer_head * bh;
231 struct sysv_dir_entry * de;
232
233 bh = sysv_find_entry(dir, dentry->d_name.name,
234 dentry->d_name.len, &de);
235 if (bh) {
236 brelse(bh);
237 return -EEXIST;
238 }
239 inode = sysv_new_inode(dir);
240 if (!inode)
241 return -ENOSPC;
242 inode->i_uid = current->fsuid;
243 init_special_inode(inode, mode, rdev);
244 mark_inode_dirty(inode);
245 error = sysv_add_entry(dir, dentry->d_name.name,
246 dentry->d_name.len, &bh, &de);
247 if (error) {
248 inode->i_nlink--;
249 mark_inode_dirty(inode);
250 iput(inode);
251 return error;
252 }
253 de->inode = inode->i_ino;
254 mark_buffer_dirty(bh);
255 brelse(bh);
256 d_instantiate(dentry, inode);
257 return 0;
258 }
259
260 static int sysv_mkdir(struct inode * dir, struct dentry *dentry, int mode)
261 {
262 int error;
263 struct inode * inode;
264 struct buffer_head * bh, *dir_block;
265 struct sysv_dir_entry * de;
266
267 bh = sysv_find_entry(dir, dentry->d_name.name,
268 dentry->d_name.len, &de);
269 if (bh) {
270 brelse(bh);
271 return -EEXIST;
272 }
273 if (dir->i_nlink >= dir->i_sb->sv_link_max)
274 return -EMLINK;
275 inode = sysv_new_inode(dir);
276 if (!inode)
277 return -ENOSPC;
278 inode->i_op = &sysv_dir_inode_operations;
279 inode->i_fop = &sysv_dir_operations;
280 inode->i_size = 2 * SYSV_DIRSIZE;
281 dir_block = sysv_file_bread(inode,0,1);
282 if (!dir_block) {
283 inode->i_nlink--;
284 mark_inode_dirty(inode);
285 iput(inode);
286 return -ENOSPC;
287 }
288 de = (struct sysv_dir_entry *) (dir_block->b_data + 0*SYSV_DIRSIZE);
289 de->inode = inode->i_ino;
290 strcpy(de->name,"."); /* rest of de->name is zero, see sysv_new_block */
291 de = (struct sysv_dir_entry *) (dir_block->b_data + 1*SYSV_DIRSIZE);
292 de->inode = dir->i_ino;
293 strcpy(de->name,".."); /* rest of de->name is zero, see sysv_new_block */
294 inode->i_nlink = 2;
295 mark_buffer_dirty(dir_block);
296 brelse(dir_block);
297 inode->i_mode = S_IFDIR | mode;
298 if (dir->i_mode & S_ISGID)
299 inode->i_mode |= S_ISGID;
300 mark_inode_dirty(inode);
301 error = sysv_add_entry(dir, dentry->d_name.name,
302 dentry->d_name.len, &bh, &de);
303 if (error) {
304 inode->i_nlink=0;
305 iput(inode);
306 return error;
307 }
308 de->inode = inode->i_ino;
309 mark_buffer_dirty(bh);
310 dir->i_nlink++;
311 mark_inode_dirty(dir);
312 brelse(bh);
313 d_instantiate(dentry, inode);
314 return 0;
315 }
316
317 /*
318 * routine to check that the specified directory is empty (for rmdir)
319 */
320 static int empty_dir(struct inode * inode)
321 {
322 struct super_block * sb;
323 unsigned long pos, block, offset; /* pos = block * block_size + offset */
324 struct buffer_head * bh;
325 struct sysv_dir_entry * de;
326
327 block = 0;
328 bh = NULL;
329 pos = offset = 2*SYSV_DIRSIZE;
330 if ((unsigned long)(inode->i_size) % SYSV_DIRSIZE)
331 goto bad_dir;
332 if (inode->i_size < pos)
333 goto bad_dir;
334 bh = sysv_file_bread(inode, 0, 0);
335 if (!bh)
336 goto bad_dir;
337 de = (struct sysv_dir_entry *) (bh->b_data + 0*SYSV_DIRSIZE);
338 if (!de->inode || strcmp(de->name,"."))
339 goto bad_dir;
340 de = (struct sysv_dir_entry *) (bh->b_data + 1*SYSV_DIRSIZE);
341 if (!de->inode || strcmp(de->name,".."))
342 goto bad_dir;
343 sb = inode->i_sb;
344 while (pos < inode->i_size) {
345 if (!bh) {
346 bh = sysv_file_bread(inode, block, 0);
347 if (!bh) {
348 /* offset = 0; */ block++;
349 pos += sb->sv_block_size;
350 continue;
351 }
352 }
353 de = (struct sysv_dir_entry *) (bh->b_data + offset);
354 pos += SYSV_DIRSIZE;
355 offset += SYSV_DIRSIZE;
356 if (de->inode) {
357 brelse(bh);
358 return 0;
359 }
360 if (offset < sb->sv_block_size)
361 continue;
362 brelse(bh);
363 bh = NULL;
364 offset = 0; block++;
365 }
366 brelse(bh);
367 return 1;
368 bad_dir:
369 brelse(bh);
370 printk("Bad directory on device %s\n",
371 kdevname(inode->i_dev));
372 return 1;
373 }
374
375 static int sysv_rmdir(struct inode * dir, struct dentry * dentry)
376 {
377 int retval;
378 struct inode * inode;
379 struct buffer_head * bh;
380 struct sysv_dir_entry * de;
381
382 inode = dentry->d_inode;
383 bh = sysv_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
384 retval = -ENOENT;
385 if (!bh || de->inode != inode->i_ino)
386 goto end_rmdir;
387
388 if (!empty_dir(inode)) {
389 retval = -ENOTEMPTY;
390 goto end_rmdir;
391 }
392 if (inode->i_nlink != 2)
393 printk("empty directory has nlink!=2 (%d)\n", inode->i_nlink);
394 de->inode = 0;
395 mark_buffer_dirty(bh);
396 inode->i_nlink=0;
397 dir->i_nlink--;
398 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
399 mark_inode_dirty(inode);
400 mark_inode_dirty(dir);
401 retval = 0;
402 end_rmdir:
403 brelse(bh);
404 return retval;
405 }
406
407 static int sysv_unlink(struct inode * dir, struct dentry * dentry)
408 {
409 int retval;
410 struct inode * inode;
411 struct buffer_head * bh;
412 struct sysv_dir_entry * de;
413
414 retval = -ENOENT;
415 inode = dentry->d_inode;
416 bh = sysv_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
417 if (!bh || de->inode != inode->i_ino)
418 goto end_unlink;
419 if (!inode->i_nlink) {
420 printk("Deleting nonexistent file (%s:%lu), %d\n",
421 kdevname(inode->i_dev), inode->i_ino, inode->i_nlink);
422 inode->i_nlink=1;
423 }
424 de->inode = 0;
425 mark_buffer_dirty(bh);
426 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
427 mark_inode_dirty(dir);
428 inode->i_nlink--;
429 inode->i_ctime = dir->i_ctime;
430 mark_inode_dirty(inode);
431 retval = 0;
432 end_unlink:
433 brelse(bh);
434 return retval;
435 }
436
437 static int sysv_symlink(struct inode * dir, struct dentry * dentry,
438 const char * symname)
439 {
440 struct inode * inode;
441 struct sysv_dir_entry * de;
442 struct buffer_head * bh;
443 int err;
444 int l;
445
446 err = -ENAMETOOLONG;
447 l = strlen(symname)+1;
448 if (l > dir->i_sb->sv_block_size_1)
449 goto out;
450 err = -ENOSPC;
451 if (!(inode = sysv_new_inode(dir)))
452 goto out;
453
454 inode->i_mode = S_IFLNK | 0777;
455 inode->i_op = &sysv_symlink_inode_operations;
456 inode->i_mapping->a_ops = &sysv_aops;
457 err = block_symlink(inode, symname, l);
458 if (err)
459 goto out_no_entry;
460 mark_inode_dirty(inode);
461 err = sysv_add_entry(dir, dentry->d_name.name,
462 dentry->d_name.len, &bh, &de);
463 if (err)
464 goto out_no_entry;
465 de->inode = inode->i_ino;
466 mark_buffer_dirty(bh);
467 brelse(bh);
468 d_instantiate(dentry, inode);
469 out:
470 return err;
471 out_no_entry:
472 inode->i_nlink--;
473 mark_inode_dirty(inode);
474 iput(inode);
475 goto out;
476 }
477
478 static int sysv_link(struct dentry * old_dentry, struct inode * dir,
479 struct dentry * dentry)
480 {
481 struct inode *oldinode = old_dentry->d_inode;
482 int error;
483 struct sysv_dir_entry * de;
484 struct buffer_head * bh;
485
486 if (S_ISDIR(oldinode->i_mode)) {
487 return -EPERM;
488 }
489 if (oldinode->i_nlink >= oldinode->i_sb->sv_link_max) {
490 return -EMLINK;
491 }
492 bh = sysv_find_entry(dir, dentry->d_name.name,
493 dentry->d_name.len, &de);
494 if (bh) {
495 brelse(bh);
496 return -EEXIST;
497 }
498 error = sysv_add_entry(dir, dentry->d_name.name,
499 dentry->d_name.len, &bh, &de);
500 if (error) {
501 brelse(bh);
502 return error;
503 }
504 de->inode = oldinode->i_ino;
505 mark_buffer_dirty(bh);
506 brelse(bh);
507 oldinode->i_nlink++;
508 oldinode->i_ctime = CURRENT_TIME;
509 mark_inode_dirty(oldinode);
510 atomic_inc(&oldinode->i_count);
511 d_instantiate(dentry, oldinode);
512 return 0;
513 }
514
515 #define PARENT_INO(buffer) \
516 (((struct sysv_dir_entry *) ((buffer) + 1*SYSV_DIRSIZE))->inode)
517
518 /*
519 * Anybody can rename anything with this: the permission checks are left to the
520 * higher-level routines.
521 */
522 static int sysv_rename(struct inode * old_dir, struct dentry * old_dentry,
523 struct inode * new_dir, struct dentry * new_dentry)
524 {
525 struct inode * old_inode, * new_inode;
526 struct buffer_head * old_bh, * new_bh, * dir_bh;
527 struct sysv_dir_entry * old_de, * new_de;
528 int retval;
529
530 old_inode = old_dentry->d_inode;
531 new_inode = new_dentry->d_inode;
532 new_bh = dir_bh = NULL;
533 old_bh = sysv_find_entry(old_dir, old_dentry->d_name.name,
534 old_dentry->d_name.len, &old_de);
535 retval = -ENOENT;
536 if (!old_bh || old_de->inode != old_inode->i_ino)
537 goto end_rename;
538 retval = -EPERM;
539 new_bh = sysv_find_entry(new_dir, new_dentry->d_name.name,
540 new_dentry->d_name.len, &new_de);
541 if (new_bh) {
542 if (!new_inode) {
543 brelse(new_bh);
544 new_bh = NULL;
545 }
546 }
547 if (S_ISDIR(old_inode->i_mode)) {
548 if (new_inode) {
549 retval = -ENOTEMPTY;
550 if (!empty_dir(new_inode))
551 goto end_rename;
552 }
553 retval = -EIO;
554 dir_bh = sysv_file_bread(old_inode, 0, 0);
555 if (!dir_bh)
556 goto end_rename;
557 if (PARENT_INO(dir_bh->b_data) != old_dir->i_ino)
558 goto end_rename;
559 retval = -EMLINK;
560 if (!new_inode && new_dir != old_dir &&
561 new_dir->i_nlink >= new_dir->i_sb->sv_link_max)
562 goto end_rename;
563 }
564 if (!new_bh) {
565 retval = sysv_add_entry(new_dir, new_dentry->d_name.name,
566 new_dentry->d_name.len, &new_bh, &new_de);
567 if (retval)
568 goto end_rename;
569 }
570 new_de->inode = old_inode->i_ino;
571 old_de->inode = 0;
572 old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME;
573 mark_inode_dirty(old_dir);
574 new_dir->i_ctime = new_dir->i_mtime = CURRENT_TIME;
575 mark_inode_dirty(new_dir);
576 if (new_inode) {
577 new_inode->i_nlink--;
578 new_inode->i_ctime = CURRENT_TIME;
579 mark_inode_dirty(new_inode);
580 }
581 mark_buffer_dirty(old_bh);
582 mark_buffer_dirty(new_bh);
583 if (dir_bh) {
584 PARENT_INO(dir_bh->b_data) = new_dir->i_ino;
585 mark_buffer_dirty(dir_bh);
586 old_dir->i_nlink--;
587 mark_inode_dirty(old_dir);
588 if (new_inode) {
589 new_inode->i_nlink--;
590 mark_inode_dirty(new_inode);
591 } else {
592 new_dir->i_nlink++;
593 mark_inode_dirty(new_dir);
594 }
595 }
596 retval = 0;
597 end_rename:
598 brelse(dir_bh);
599 brelse(old_bh);
600 brelse(new_bh);
601 return retval;
602 }
603
604 /*
605 * directories can handle most operations...
606 */
607 struct inode_operations sysv_dir_inode_operations = {
608 create: sysv_create,
609 lookup: sysv_lookup,
610 link: sysv_link,
611 unlink: sysv_unlink,
612 symlink: sysv_symlink,
613 mkdir: sysv_mkdir,
614 rmdir: sysv_rmdir,
615 mknod: sysv_mknod,
616 rename: sysv_rename,
617 setattr: sysv_notify_change,
618 };
619
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