?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
* better
[mascara-docs.git] / i386 / linux-2.3.21 / fs / sysv / namei.c
blobe27ac8d838ff04473aef08946bb18648fca4b132
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 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, 1);
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 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_mode = mode;
208 mark_inode_dirty(inode);
209 error = sysv_add_entry(dir, dentry->d_name.name,
210 dentry->d_name.len, &bh, &de);
211 if (error) {
212 inode->i_nlink--;
213 mark_inode_dirty(inode);
214 iput(inode);
215 return error;
216 }
217 de->inode = inode->i_ino;
218 mark_buffer_dirty(bh, 1);
219 brelse(bh);
220 d_instantiate(dentry, inode);
221 return 0;
222 }
223
224 int sysv_mknod(struct inode * dir, struct dentry * dentry, int mode, int rdev)
225 {
226 int error;
227 struct inode * inode;
228 struct buffer_head * bh;
229 struct sysv_dir_entry * de;
230
231 bh = sysv_find_entry(dir, dentry->d_name.name,
232 dentry->d_name.len, &de);
233 if (bh) {
234 brelse(bh);
235 return -EEXIST;
236 }
237 inode = sysv_new_inode(dir);
238 if (!inode)
239 return -ENOSPC;
240 inode->i_uid = current->fsuid;
241 init_special_inode(inode, mode, rdev);
242 mark_inode_dirty(inode);
243 error = sysv_add_entry(dir, dentry->d_name.name,
244 dentry->d_name.len, &bh, &de);
245 if (error) {
246 inode->i_nlink--;
247 mark_inode_dirty(inode);
248 iput(inode);
249 return error;
250 }
251 de->inode = inode->i_ino;
252 mark_buffer_dirty(bh, 1);
253 brelse(bh);
254 d_instantiate(dentry, inode);
255 return 0;
256 }
257
258 int sysv_mkdir(struct inode * dir, struct dentry *dentry, int mode)
259 {
260 int error;
261 struct inode * inode;
262 struct buffer_head * bh, *dir_block;
263 struct sysv_dir_entry * de;
264
265 bh = sysv_find_entry(dir, dentry->d_name.name,
266 dentry->d_name.len, &de);
267 if (bh) {
268 brelse(bh);
269 return -EEXIST;
270 }
271 if (dir->i_nlink >= dir->i_sb->sv_link_max)
272 return -EMLINK;
273 inode = sysv_new_inode(dir);
274 if (!inode)
275 return -ENOSPC;
276 inode->i_op = &sysv_dir_inode_operations;
277 inode->i_size = 2 * SYSV_DIRSIZE;
278 dir_block = sysv_file_bread(inode,0,1);
279 if (!dir_block) {
280 inode->i_nlink--;
281 mark_inode_dirty(inode);
282 iput(inode);
283 return -ENOSPC;
284 }
285 de = (struct sysv_dir_entry *) (dir_block->b_data + 0*SYSV_DIRSIZE);
286 de->inode = inode->i_ino;
287 strcpy(de->name,"."); /* rest of de->name is zero, see sysv_new_block */
288 de = (struct sysv_dir_entry *) (dir_block->b_data + 1*SYSV_DIRSIZE);
289 de->inode = dir->i_ino;
290 strcpy(de->name,".."); /* rest of de->name is zero, see sysv_new_block */
291 inode->i_nlink = 2;
292 mark_buffer_dirty(dir_block, 1);
293 brelse(dir_block);
294 inode->i_mode = S_IFDIR | mode;
295 if (dir->i_mode & S_ISGID)
296 inode->i_mode |= S_ISGID;
297 mark_inode_dirty(inode);
298 error = sysv_add_entry(dir, dentry->d_name.name,
299 dentry->d_name.len, &bh, &de);
300 if (error) {
301 inode->i_nlink=0;
302 iput(inode);
303 return error;
304 }
305 de->inode = inode->i_ino;
306 mark_buffer_dirty(bh, 1);
307 dir->i_nlink++;
308 mark_inode_dirty(dir);
309 brelse(bh);
310 d_instantiate(dentry, inode);
311 return 0;
312 }
313
314 /*
315 * routine to check that the specified directory is empty (for rmdir)
316 */
317 static int empty_dir(struct inode * inode)
318 {
319 struct super_block * sb;
320 unsigned long pos, block, offset; /* pos = block * block_size + offset */
321 struct buffer_head * bh;
322 struct sysv_dir_entry * de;
323
324 block = 0;
325 bh = NULL;
326 pos = offset = 2*SYSV_DIRSIZE;
327 if (inode->i_size % SYSV_DIRSIZE)
328 goto bad_dir;
329 if (inode->i_size < pos)
330 goto bad_dir;
331 bh = sysv_file_bread(inode, 0, 0);
332 if (!bh)
333 goto bad_dir;
334 de = (struct sysv_dir_entry *) (bh->b_data + 0*SYSV_DIRSIZE);
335 if (!de->inode || strcmp(de->name,"."))
336 goto bad_dir;
337 de = (struct sysv_dir_entry *) (bh->b_data + 1*SYSV_DIRSIZE);
338 if (!de->inode || strcmp(de->name,".."))
339 goto bad_dir;
340 sb = inode->i_sb;
341 while (pos < inode->i_size) {
342 if (!bh) {
343 bh = sysv_file_bread(inode, block, 0);
344 if (!bh) {
345 /* offset = 0; */ block++;
346 pos += sb->sv_block_size;
347 continue;
348 }
349 }
350 de = (struct sysv_dir_entry *) (bh->b_data + offset);
351 pos += SYSV_DIRSIZE;
352 offset += SYSV_DIRSIZE;
353 if (de->inode) {
354 brelse(bh);
355 return 0;
356 }
357 if (offset < sb->sv_block_size)
358 continue;
359 brelse(bh);
360 bh = NULL;
361 offset = 0; block++;
362 }
363 brelse(bh);
364 return 1;
365 bad_dir:
366 brelse(bh);
367 printk("Bad directory on device %s\n",
368 kdevname(inode->i_dev));
369 return 1;
370 }
371
372 int sysv_rmdir(struct inode * dir, struct dentry * dentry)
373 {
374 int retval;
375 struct inode * inode;
376 struct buffer_head * bh;
377 struct sysv_dir_entry * de;
378
379 inode = dentry->d_inode;
380 bh = sysv_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
381 retval = -ENOENT;
382 if (!bh || de->inode != inode->i_ino)
383 goto end_rmdir;
384
385 if (!empty_dir(inode)) {
386 retval = -ENOTEMPTY;
387 goto end_rmdir;
388 }
389 if (!list_empty(&dentry->d_hash)) {
390 retval = -EBUSY;
391 goto end_rmdir;
392 }
393 if (inode->i_nlink != 2)
394 printk("empty directory has nlink!=2 (%d)\n", inode->i_nlink);
395 de->inode = 0;
396 mark_buffer_dirty(bh, 1);
397 inode->i_nlink=0;
398 dir->i_nlink--;
399 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
400 mark_inode_dirty(inode);
401 mark_inode_dirty(dir);
402 d_delete(dentry);
403 retval = 0;
404 end_rmdir:
405 brelse(bh);
406 return retval;
407 }
408
409 int sysv_unlink(struct inode * dir, struct dentry * dentry)
410 {
411 int retval;
412 struct inode * inode;
413 struct buffer_head * bh;
414 struct sysv_dir_entry * de;
415
416 retval = -ENOENT;
417 inode = dentry->d_inode;
418 bh = sysv_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
419 if (!bh || de->inode != inode->i_ino)
420 goto end_unlink;
421 if (!inode->i_nlink) {
422 printk("Deleting nonexistent file (%s:%lu), %d\n",
423 kdevname(inode->i_dev), inode->i_ino, inode->i_nlink);
424 inode->i_nlink=1;
425 }
426 de->inode = 0;
427 mark_buffer_dirty(bh, 1);
428 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
429 mark_inode_dirty(dir);
430 inode->i_nlink--;
431 inode->i_ctime = dir->i_ctime;
432 mark_inode_dirty(inode);
433 d_delete(dentry);
434 retval = 0;
435 end_unlink:
436 brelse(bh);
437 return retval;
438 }
439
440 int sysv_symlink(struct inode * dir, struct dentry * dentry,
441 const char * symname)
442 {
443 struct sysv_dir_entry * de;
444 struct inode * inode;
445 struct buffer_head * name_block;
446 char * name_block_data;
447 struct super_block * sb;
448 int i;
449 char c;
450 struct buffer_head * bh;
451
452 if (!(inode = sysv_new_inode(dir)))
453 return -ENOSPC;
454
455 inode->i_mode = S_IFLNK | 0777;
456 inode->i_op = &sysv_symlink_inode_operations;
457 name_block = sysv_file_bread(inode, 0, 1);
458 if (!name_block) {
459 inode->i_nlink--;
460 mark_inode_dirty(inode);
461 iput(inode);
462 return -ENOSPC;
463 }
464 sb = inode->i_sb;
465 name_block_data = name_block->b_data;
466 i = 0;
467 while (i < sb->sv_block_size_1 && (c = *(symname++)))
468 name_block_data[i++] = c;
469 name_block_data[i] = 0;
470 mark_buffer_dirty(name_block, 1);
471 brelse(name_block);
472 inode->i_size = i;
473 mark_inode_dirty(inode);
474 bh = sysv_find_entry(dir, dentry->d_name.name,
475 dentry->d_name.len, &de);
476 if (bh) {
477 inode->i_nlink--;
478 mark_inode_dirty(inode);
479 iput(inode);
480 brelse(bh);
481 return -EEXIST;
482 }
483 i = sysv_add_entry(dir, dentry->d_name.name,
484 dentry->d_name.len, &bh, &de);
485 if (i) {
486 inode->i_nlink--;
487 mark_inode_dirty(inode);
488 iput(inode);
489 return i;
490 }
491 de->inode = inode->i_ino;
492 mark_buffer_dirty(bh, 1);
493 brelse(bh);
494 d_instantiate(dentry, inode);
495 return 0;
496 }
497
498 int sysv_link(struct dentry * old_dentry, struct inode * dir,
499 struct dentry * dentry)
500 {
501 struct inode *oldinode = old_dentry->d_inode;
502 int error;
503 struct sysv_dir_entry * de;
504 struct buffer_head * bh;
505
506 if (S_ISDIR(oldinode->i_mode)) {
507 return -EPERM;
508 }
509 if (oldinode->i_nlink >= oldinode->i_sb->sv_link_max) {
510 return -EMLINK;
511 }
512 bh = sysv_find_entry(dir, dentry->d_name.name,
513 dentry->d_name.len, &de);
514 if (bh) {
515 brelse(bh);
516 return -EEXIST;
517 }
518 error = sysv_add_entry(dir, dentry->d_name.name,
519 dentry->d_name.len, &bh, &de);
520 if (error) {
521 brelse(bh);
522 return error;
523 }
524 de->inode = oldinode->i_ino;
525 mark_buffer_dirty(bh, 1);
526 brelse(bh);
527 oldinode->i_nlink++;
528 oldinode->i_ctime = CURRENT_TIME;
529 mark_inode_dirty(oldinode);
530 oldinode->i_count++;
531 d_instantiate(dentry, oldinode);
532 return 0;
533 }
534
535 #define PARENT_INO(buffer) \
536 (((struct sysv_dir_entry *) ((buffer) + 1*SYSV_DIRSIZE))->inode)
537
538 /*
539 * Anybody can rename anything with this: the permission checks are left to the
540 * higher-level routines.
541 */
542 int sysv_rename(struct inode * old_dir, struct dentry * old_dentry,
543 struct inode * new_dir, struct dentry * new_dentry)
544 {
545 struct inode * old_inode, * new_inode;
546 struct buffer_head * old_bh, * new_bh, * dir_bh;
547 struct sysv_dir_entry * old_de, * new_de;
548 int retval;
549
550 old_inode = old_dentry->d_inode;
551 new_inode = new_dentry->d_inode;
552 new_bh = dir_bh = NULL;
553 old_bh = sysv_find_entry(old_dir, old_dentry->d_name.name,
554 old_dentry->d_name.len, &old_de);
555 retval = -ENOENT;
556 if (!old_bh || old_de->inode != old_inode->i_ino)
557 goto end_rename;
558 retval = -EPERM;
559 new_bh = sysv_find_entry(new_dir, new_dentry->d_name.name,
560 new_dentry->d_name.len, &new_de);
561 if (new_bh) {
562 if (!new_inode) {
563 brelse(new_bh);
564 new_bh = NULL;
565 }
566 }
567 if (S_ISDIR(old_inode->i_mode)) {
568 if (new_inode) {
569 retval = -ENOTEMPTY;
570 if (!empty_dir(new_inode))
571 goto end_rename;
572 }
573 retval = -EIO;
574 dir_bh = sysv_file_bread(old_inode, 0, 0);
575 if (!dir_bh)
576 goto end_rename;
577 if (PARENT_INO(dir_bh->b_data) != old_dir->i_ino)
578 goto end_rename;
579 retval = -EMLINK;
580 if (!new_inode && new_dir != old_dir &&
581 new_dir->i_nlink >= new_dir->i_sb->sv_link_max)
582 goto end_rename;
583 }
584 if (!new_bh) {
585 retval = sysv_add_entry(new_dir, new_dentry->d_name.name,
586 new_dentry->d_name.len, &new_bh, &new_de);
587 if (retval)
588 goto end_rename;
589 }
590 new_de->inode = old_inode->i_ino;
591 old_de->inode = 0;
592 old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME;
593 mark_inode_dirty(old_dir);
594 new_dir->i_ctime = new_dir->i_mtime = CURRENT_TIME;
595 mark_inode_dirty(new_dir);
596 if (new_inode) {
597 new_inode->i_nlink--;
598 new_inode->i_ctime = CURRENT_TIME;
599 mark_inode_dirty(new_inode);
600 }
601 mark_buffer_dirty(old_bh, 1);
602 mark_buffer_dirty(new_bh, 1);
603 if (dir_bh) {
604 PARENT_INO(dir_bh->b_data) = new_dir->i_ino;
605 mark_buffer_dirty(dir_bh, 1);
606 old_dir->i_nlink--;
607 mark_inode_dirty(old_dir);
608 if (new_inode) {
609 new_inode->i_nlink--;
610 mark_inode_dirty(new_inode);
611 } else {
612 new_dir->i_nlink++;
613 mark_inode_dirty(new_dir);
614 }
615 }
616 retval = 0;
617 end_rename:
618 brelse(dir_bh);
619 brelse(old_bh);
620 brelse(new_bh);
621 return retval;
622 }