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[/] [or1k/] [trunk/] [rc203soc/] [sw/] [uClinux/] [fs/] [sysv/] [namei.c] - Blame information for rev 1777

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Line No. Rev Author Line
1 1628 jcastillo 
/*
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 
 */
13 
 
14 
#include <linux/sched.h>
15 
#include <linux/kernel.h>
16 
#include <linux/fs.h>
17 
#include <linux/sysv_fs.h>
18 
#include <linux/string.h>
19 
#include <linux/stat.h>
20 
#include <linux/errno.h>
21 
 
22 
/* compare strings: name[0..len-1] (not zero-terminated) and
23 
 * buffer[0..] (filled with zeroes up to buffer[0..maxlen-1])
24 
 */
25 
static inline int namecompare(int len, int maxlen,
26 
        const char * name, const char * buffer)
27 
{
28 
        if (len > maxlen)
29 
                return 0;
30 
        if (len < maxlen && buffer[len])
31 
                return 0;
32 
        return !memcmp(name, buffer, len);
33 
}
34 
 
35 
/*
36 
 * ok, we cannot use strncmp, as the name is not in our data space. [Now it is!]
37 
 * Thus we'll have to use sysv_match. No big problem. Match also makes
38 
 * some sanity tests.
39 
 *
40 
 * NOTE! unlike strncmp, sysv_match returns 1 for success, 0 for failure.
41 
 */
42 
static int sysv_match(int len, const char * name, struct sysv_dir_entry * de)
43 
{
44 
        if (!de->inode || len > SYSV_NAMELEN)
45 
                return 0;
46 
        /* "" means "." ---> so paths like "/usr/lib//libc.a" work */
47 
        if (!len && (de->name[0]=='.') && (de->name[1]=='\0'))
48 
                return 1;
49 
        return namecompare(len,SYSV_NAMELEN,name,de->name);
50 
}
51 
 
52 
/*
53 
 *      sysv_find_entry()
54 
 *
55 
 * finds an entry in the specified directory with the wanted name. It
56 
 * returns the cache buffer in which the entry was found, and the entry
57 
 * itself (as a parameter - res_dir). It does NOT read the inode of the
58 
 * entry - you'll have to do that yourself if you want to.
59 
 */
60 
static struct buffer_head * sysv_find_entry(struct inode * dir,
61 
        const char * name, int namelen, struct sysv_dir_entry ** res_dir)
62 
{
63 
        struct super_block * sb;
64 
        unsigned long pos, block, offset; /* pos = block * block_size + offset */
65 
        struct buffer_head * bh;
66 
 
67 
        *res_dir = NULL;
68 
        if (!dir)
69 
                return 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 
        bh = NULL;
77 
        pos = block = offset = 0;
78 
        while (pos < dir->i_size) {
79 
                if (!bh) {
80 
                        bh = sysv_file_bread(dir,block,0);
81 
                        if (!bh) {
82 
                                /* offset = 0; */ block++;
83 
                                pos += sb->sv_block_size;
84 
                                continue;
85 
                        }
86 
                }
87 
                if (sysv_match(namelen, name,
88 
                               *res_dir = (struct sysv_dir_entry *) (bh->b_data + offset) ))
89 
                        return bh;
90 
                pos += SYSV_DIRSIZE;
91 
                offset += SYSV_DIRSIZE;
92 
                if (offset < sb->sv_block_size)
93 
                        continue;
94 
                brelse(bh);
95 
                bh = NULL;
96 
                offset = 0; block++;
97 
        }
98 
        brelse(bh);
99 
        *res_dir = NULL;
100 
        return NULL;
101 
}
102 
 
103 
int sysv_lookup(struct inode * dir,const char * name, int len,
104 
        struct inode ** result)
105 
{
106 
        int ino;
107 
        struct sysv_dir_entry * de;
108 
        struct buffer_head * bh;
109 
 
110 
        *result = NULL;
111 
        if (!dir)
112 
                return -ENOENT;
113 
        if (!S_ISDIR(dir->i_mode)) {
114 
                iput(dir);
115 
                return -ENOENT;
116 
        }
117 
        if (!(bh = sysv_find_entry(dir,name,len,&de))) {
118 
                iput(dir);
119 
                return -ENOENT;
120 
        }
121 
        ino = de->inode;
122 
        brelse(bh);
123 
        if (!(*result = iget(dir->i_sb,ino))) {
124 
                iput(dir);
125 
                return -EACCES;
126 
        }
127 
        iput(dir);
128 
        return 0;
129 
}
130 
 
131 
/*
132 
 *      sysv_add_entry()
133 
 *
134 
 * adds a file entry to the specified directory, returning a possible
135 
 * error value if it fails.
136 
 *
137 
 * NOTE!! The inode part of 'de' is left at 0 - which means you
138 
 * may not sleep between calling this and putting something into
139 
 * the entry, as someone else might have used it while you slept.
140 
 */
141 
static int sysv_add_entry(struct inode * dir,
142 
        const char * name, int namelen,
143 
        struct buffer_head ** res_buf,
144 
        struct sysv_dir_entry ** res_dir)
145 
{
146 
        struct super_block * sb;
147 
        int i;
148 
        unsigned long pos, block, offset; /* pos = block * block_size + offset */
149 
        struct buffer_head * bh;
150 
        struct sysv_dir_entry * de;
151 
 
152 
        *res_buf = NULL;
153 
        *res_dir = NULL;
154 
        if (!dir)
155 
                return -ENOENT;
156 
        sb = dir->i_sb;
157 
        if (namelen > SYSV_NAMELEN)
158 
                if (sb->sv_truncate)
159 
                        namelen = SYSV_NAMELEN;
160 
                else
161 
                        return -ENAMETOOLONG;
162 
        if (!namelen)
163 
                return -ENOENT;
164 
        bh = NULL;
165 
        pos = block = offset = 0;
166 
        while (1) {
167 
                if (!bh) {
168 
                        bh = sysv_file_bread(dir,block,1);
169 
                        if (!bh)
170 
                                return -ENOSPC;
171 
                }
172 
                de = (struct sysv_dir_entry *) (bh->b_data + offset);
173 
                pos += SYSV_DIRSIZE;
174 
                offset += SYSV_DIRSIZE;
175 
                if (pos > dir->i_size) {
176 
                        de->inode = 0;
177 
                        dir->i_size = pos;
178 
                        dir->i_dirt = 1;
179 
                }
180 
                if (de->inode) {
181 
                        if (namecompare(namelen, SYSV_NAMELEN, name, de->name)) {
182 
                                brelse(bh);
183 
                                return -EEXIST;
184 
                        }
185 
                } else {
186 
                        dir->i_mtime = dir->i_ctime = CURRENT_TIME;
187 
                        dir->i_dirt = 1;
188 
                        for (i = 0; i < SYSV_NAMELEN ; i++)
189 
                                de->name[i] = (i < namelen) ? name[i] : 0;
190 
                        mark_buffer_dirty(bh, 1);
191 
                        *res_dir = de;
192 
                        break;
193 
                }
194 
                if (offset < sb->sv_block_size)
195 
                        continue;
196 
                brelse(bh);
197 
                bh = NULL;
198 
                offset = 0; block++;
199 
        }
200 
        *res_buf = bh;
201 
        return 0;
202 
}
203 
 
204 
int sysv_create(struct inode * dir,const char * name, int len, int mode,
205 
        struct inode ** result)
206 
{
207 
        int error;
208 
        struct inode * inode;
209 
        struct buffer_head * bh;
210 
        struct sysv_dir_entry * de;
211 
 
212 
        *result = NULL;
213 
        if (!dir)
214 
                return -ENOENT;
215 
        inode = sysv_new_inode(dir);
216 
        if (!inode) {
217 
                iput(dir);
218 
                return -ENOSPC;
219 
        }
220 
        inode->i_op = &sysv_file_inode_operations;
221 
        inode->i_mode = mode;
222 
        inode->i_dirt = 1;
223 
        error = sysv_add_entry(dir,name,len, &bh ,&de);
224 
        if (error) {
225 
                inode->i_nlink--;
226 
                inode->i_dirt = 1;
227 
                iput(inode);
228 
                iput(dir);
229 
                return error;
230 
        }
231 
        de->inode = inode->i_ino;
232 
        mark_buffer_dirty(bh, 1);
233 
        brelse(bh);
234 
        iput(dir);
235 
        *result = inode;
236 
        return 0;
237 
}
238 
 
239 
int sysv_mknod(struct inode * dir, const char * name, int len, int mode, int rdev)
240 
{
241 
        int error;
242 
        struct inode * inode;
243 
        struct buffer_head * bh;
244 
        struct sysv_dir_entry * de;
245 
 
246 
        if (!dir)
247 
                return -ENOENT;
248 
        bh = sysv_find_entry(dir,name,len,&de);
249 
        if (bh) {
250 
                brelse(bh);
251 
                iput(dir);
252 
                return -EEXIST;
253 
        }
254 
        inode = sysv_new_inode(dir);
255 
        if (!inode) {
256 
                iput(dir);
257 
                return -ENOSPC;
258 
        }
259 
        inode->i_uid = current->fsuid;
260 
        inode->i_mode = mode;
261 
        inode->i_op = NULL;
262 
        if (S_ISREG(inode->i_mode))
263 
                inode->i_op = &sysv_file_inode_operations;
264 
        else if (S_ISDIR(inode->i_mode)) {
265 
                inode->i_op = &sysv_dir_inode_operations;
266 
                if (dir->i_mode & S_ISGID)
267 
                        inode->i_mode |= S_ISGID;
268 
        }
269 
        else if (S_ISLNK(inode->i_mode))
270 
                inode->i_op = &sysv_symlink_inode_operations;
271 
        else if (S_ISCHR(inode->i_mode))
272 
                inode->i_op = &chrdev_inode_operations;
273 
        else if (S_ISBLK(inode->i_mode))
274 
                inode->i_op = &blkdev_inode_operations;
275 
        else if (S_ISFIFO(inode->i_mode))
276 
                init_fifo(inode);
277 
        if (S_ISBLK(mode) || S_ISCHR(mode))
278 
                inode->i_rdev = to_kdev_t(rdev);
279 
        inode->i_dirt = 1;
280 
        error = sysv_add_entry(dir, name, len, &bh, &de);
281 
        if (error) {
282 
                inode->i_nlink--;
283 
                inode->i_dirt = 1;
284 
                iput(inode);
285 
                iput(dir);
286 
                return error;
287 
        }
288 
        de->inode = inode->i_ino;
289 
        mark_buffer_dirty(bh, 1);
290 
        brelse(bh);
291 
        iput(dir);
292 
        iput(inode);
293 
        return 0;
294 
}
295 
 
296 
int sysv_mkdir(struct inode * dir, const char * name, int len, int mode)
297 
{
298 
        int error;
299 
        struct inode * inode;
300 
        struct buffer_head * bh, *dir_block;
301 
        struct sysv_dir_entry * de;
302 
 
303 
        if (!dir) {
304 
                iput(dir);
305 
                return -EINVAL;
306 
        }
307 
        bh = sysv_find_entry(dir,name,len,&de);
308 
        if (bh) {
309 
                brelse(bh);
310 
                iput(dir);
311 
                return -EEXIST;
312 
        }
313 
        if (dir->i_nlink >= dir->i_sb->sv_link_max) {
314 
                iput(dir);
315 
                return -EMLINK;
316 
        }
317 
        inode = sysv_new_inode(dir);
318 
        if (!inode) {
319 
                iput(dir);
320 
                return -ENOSPC;
321 
        }
322 
        inode->i_op = &sysv_dir_inode_operations;
323 
        inode->i_size = 2 * SYSV_DIRSIZE;
324 
        dir_block = sysv_file_bread(inode,0,1);
325 
        if (!dir_block) {
326 
                iput(dir);
327 
                inode->i_nlink--;
328 
                inode->i_dirt = 1;
329 
                iput(inode);
330 
                return -ENOSPC;
331 
        }
332 
        de = (struct sysv_dir_entry *) (dir_block->b_data + 0*SYSV_DIRSIZE);
333 
        de->inode = inode->i_ino;
334 
        strcpy(de->name,"."); /* rest of de->name is zero, see sysv_new_block */
335 
        de = (struct sysv_dir_entry *) (dir_block->b_data + 1*SYSV_DIRSIZE);
336 
        de->inode = dir->i_ino;
337 
        strcpy(de->name,".."); /* rest of de->name is zero, see sysv_new_block */
338 
        inode->i_nlink = 2;
339 
        mark_buffer_dirty(dir_block, 1);
340 
        brelse(dir_block);
341 
        inode->i_mode = S_IFDIR | (mode & 0777 & ~current->fs->umask);
342 
        if (dir->i_mode & S_ISGID)
343 
                inode->i_mode |= S_ISGID;
344 
        inode->i_dirt = 1;
345 
        error = sysv_add_entry(dir, name, len, &bh, &de);
346 
        if (error) {
347 
                iput(dir);
348 
                inode->i_nlink=0;
349 
                iput(inode);
350 
                return error;
351 
        }
352 
        de->inode = inode->i_ino;
353 
        mark_buffer_dirty(bh, 1);
354 
        dir->i_nlink++;
355 
        dir->i_dirt = 1;
356 
        iput(dir);
357 
        iput(inode);
358 
        brelse(bh);
359 
        return 0;
360 
}
361 
 
362 
/*
363 
 * routine to check that the specified directory is empty (for rmdir)
364 
 */
365 
static int empty_dir(struct inode * inode)
366 
{
367 
        struct super_block * sb;
368 
        unsigned long pos, block, offset; /* pos = block * block_size + offset */
369 
        struct buffer_head * bh;
370 
        struct sysv_dir_entry * de;
371 
 
372 
        if (!inode)
373 
                return 1;
374 
        block = 0;
375 
        bh = NULL;
376 
        pos = offset = 2*SYSV_DIRSIZE;
377 
        if (inode->i_size % SYSV_DIRSIZE)
378 
                goto bad_dir;
379 
        if (inode->i_size < pos)
380 
                goto bad_dir;
381 
        bh = sysv_file_bread(inode,0,0);
382 
        if (!bh)
383 
                goto bad_dir;
384 
        de = (struct sysv_dir_entry *) (bh->b_data + 0*SYSV_DIRSIZE);
385 
        if (!de->inode || strcmp(de->name,"."))
386 
                goto bad_dir;
387 
        de = (struct sysv_dir_entry *) (bh->b_data + 1*SYSV_DIRSIZE);
388 
        if (!de->inode || strcmp(de->name,".."))
389 
                goto bad_dir;
390 
        sb = inode->i_sb;
391 
        while (pos < inode->i_size) {
392 
                if (!bh) {
393 
                        bh = sysv_file_bread(inode,block,0);
394 
                        if (!bh) {
395 
                                /* offset = 0; */ block++;
396 
                                pos += sb->sv_block_size;
397 
                                continue;
398 
                        }
399 
                }
400 
                de = (struct sysv_dir_entry *) (bh->b_data + offset);
401 
                pos += SYSV_DIRSIZE;
402 
                offset += SYSV_DIRSIZE;
403 
                if (de->inode) {
404 
                        brelse(bh);
405 
                        return 0;
406 
                }
407 
                if (offset < sb->sv_block_size)
408 
                        continue;
409 
                brelse(bh);
410 
                bh = NULL;
411 
                offset = 0; block++;
412 
        }
413 
        brelse(bh);
414 
        return 1;
415 
bad_dir:
416 
        brelse(bh);
417 
        printk("Bad directory on device %s\n",
418 
               kdevname(inode->i_dev));
419 
        return 1;
420 
}
421 
 
422 
int sysv_rmdir(struct inode * dir, const char * name, int len)
423 
{
424 
        int retval;
425 
        struct inode * inode;
426 
        struct buffer_head * bh;
427 
        struct sysv_dir_entry * de;
428 
 
429 
        inode = NULL;
430 
        bh = sysv_find_entry(dir,name,len,&de);
431 
        retval = -ENOENT;
432 
        if (!bh)
433 
                goto end_rmdir;
434 
        retval = -EPERM;
435 
        if (!(inode = iget(dir->i_sb, de->inode)))
436 
                goto end_rmdir;
437 
        if ((dir->i_mode & S_ISVTX) && !fsuser() &&
438 
            current->fsuid != inode->i_uid &&
439 
            current->fsuid != dir->i_uid)
440 
                goto end_rmdir;
441 
        if (inode->i_dev != dir->i_dev)
442 
                goto end_rmdir;
443 
        if (inode == dir)       /* we may not delete ".", but "../dir" is ok */
444 
                goto end_rmdir;
445 
        if (!S_ISDIR(inode->i_mode)) {
446 
                retval = -ENOTDIR;
447 
                goto end_rmdir;
448 
        }
449 
        if (!empty_dir(inode)) {
450 
                retval = -ENOTEMPTY;
451 
                goto end_rmdir;
452 
        }
453 
        if (de->inode != inode->i_ino) {
454 
                retval = -ENOENT;
455 
                goto end_rmdir;
456 
        }
457 
        if (inode->i_count > 1) {
458 
                retval = -EBUSY;
459 
                goto end_rmdir;
460 
        }
461 
        if (inode->i_nlink != 2)
462 
                printk("empty directory has nlink!=2 (%d)\n",inode->i_nlink);
463 
        de->inode = 0;
464 
        mark_buffer_dirty(bh, 1);
465 
        inode->i_nlink=0;
466 
        inode->i_dirt=1;
467 
        dir->i_nlink--;
468 
        inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
469 
        dir->i_dirt=1;
470 
        retval = 0;
471 
end_rmdir:
472 
        iput(dir);
473 
        iput(inode);
474 
        brelse(bh);
475 
        return retval;
476 
}
477 
 
478 
int sysv_unlink(struct inode * dir, const char * name, int len)
479 
{
480 
        int retval;
481 
        struct inode * inode;
482 
        struct buffer_head * bh;
483 
        struct sysv_dir_entry * de;
484 
 
485 
repeat:
486 
        retval = -ENOENT;
487 
        inode = NULL;
488 
        bh = sysv_find_entry(dir,name,len,&de);
489 
        if (!bh)
490 
                goto end_unlink;
491 
        if (!(inode = iget(dir->i_sb, de->inode)))
492 
                goto end_unlink;
493 
        retval = -EPERM;
494 
        if (S_ISDIR(inode->i_mode))
495 
                goto end_unlink;
496 
        if (de->inode != inode->i_ino) {
497 
                iput(inode);
498 
                brelse(bh);
499 
                current->counter = 0;
500 
                schedule();
501 
                goto repeat;
502 
        }
503 
        if ((dir->i_mode & S_ISVTX) && !fsuser() &&
504 
            current->fsuid != inode->i_uid &&
505 
            current->fsuid != dir->i_uid)
506 
                goto end_unlink;
507 
        if (de->inode != inode->i_ino) {
508 
                retval = -ENOENT;
509 
                goto end_unlink;
510 
        }
511 
        if (!inode->i_nlink) {
512 
                printk("Deleting nonexistent file (%s:%lu), %d\n",
513 
                       kdevname(inode->i_dev),
514 
                       inode->i_ino, inode->i_nlink);
515 
                inode->i_nlink=1;
516 
        }
517 
        de->inode = 0;
518 
        mark_buffer_dirty(bh, 1);
519 
        dir->i_ctime = dir->i_mtime = CURRENT_TIME;
520 
        dir->i_dirt = 1;
521 
        inode->i_nlink--;
522 
        inode->i_ctime = dir->i_ctime;
523 
        inode->i_dirt = 1;
524 
        retval = 0;
525 
end_unlink:
526 
        brelse(bh);
527 
        iput(inode);
528 
        iput(dir);
529 
        return retval;
530 
}
531 
 
532 
int sysv_symlink(struct inode * dir, const char * name, int len, const char * symname)
533 
{
534 
        struct sysv_dir_entry * de;
535 
        struct inode * inode;
536 
        struct buffer_head * name_block;
537 
        char * name_block_data;
538 
        struct super_block * sb;
539 
        int i;
540 
        char c;
541 
        struct buffer_head * bh;
542 
 
543 
        if (!(inode = sysv_new_inode(dir))) {
544 
                iput(dir);
545 
                return -ENOSPC;
546 
        }
547 
        inode->i_mode = S_IFLNK | 0777;
548 
        inode->i_op = &sysv_symlink_inode_operations;
549 
        name_block = sysv_file_bread(inode,0,1);
550 
        if (!name_block) {
551 
                iput(dir);
552 
                inode->i_nlink--;
553 
                inode->i_dirt = 1;
554 
                iput(inode);
555 
                return -ENOSPC;
556 
        }
557 
        sb = inode->i_sb;
558 
        name_block_data = name_block->b_data;
559 
        i = 0;
560 
        while (i < sb->sv_block_size_1 && (c = *(symname++)))
561 
                name_block_data[i++] = c;
562 
        name_block_data[i] = 0;
563 
        mark_buffer_dirty(name_block, 1);
564 
        brelse(name_block);
565 
        inode->i_size = i;
566 
        inode->i_dirt = 1;
567 
        bh = sysv_find_entry(dir,name,len,&de);
568 
        if (bh) {
569 
                inode->i_nlink--;
570 
                inode->i_dirt = 1;
571 
                iput(inode);
572 
                brelse(bh);
573 
                iput(dir);
574 
                return -EEXIST;
575 
        }
576 
        i = sysv_add_entry(dir, name, len, &bh, &de);
577 
        if (i) {
578 
                inode->i_nlink--;
579 
                inode->i_dirt = 1;
580 
                iput(inode);
581 
                iput(dir);
582 
                return i;
583 
        }
584 
        de->inode = inode->i_ino;
585 
        mark_buffer_dirty(bh, 1);
586 
        brelse(bh);
587 
        iput(dir);
588 
        iput(inode);
589 
        return 0;
590 
}
591 
 
592 
int sysv_link(struct inode * oldinode, struct inode * dir, const char * name, int len)
593 
{
594 
        int error;
595 
        struct sysv_dir_entry * de;
596 
        struct buffer_head * bh;
597 
 
598 
        if (S_ISDIR(oldinode->i_mode)) {
599 
                iput(oldinode);
600 
                iput(dir);
601 
                return -EPERM;
602 
        }
603 
        if (oldinode->i_nlink >= oldinode->i_sb->sv_link_max) {
604 
                iput(oldinode);
605 
                iput(dir);
606 
                return -EMLINK;
607 
        }
608 
        bh = sysv_find_entry(dir,name,len,&de);
609 
        if (bh) {
610 
                brelse(bh);
611 
                iput(dir);
612 
                iput(oldinode);
613 
                return -EEXIST;
614 
        }
615 
        error = sysv_add_entry(dir, name, len, &bh, &de);
616 
        if (error) {
617 
                iput(dir);
618 
                iput(oldinode);
619 
                return error;
620 
        }
621 
        de->inode = oldinode->i_ino;
622 
        mark_buffer_dirty(bh, 1);
623 
        brelse(bh);
624 
        iput(dir);
625 
        oldinode->i_nlink++;
626 
        oldinode->i_ctime = CURRENT_TIME;
627 
        oldinode->i_dirt = 1;
628 
        iput(oldinode);
629 
        return 0;
630 
}
631 
 
632 
/* return 1 if `new' is a subdir of `old' on the same device */
633 
static int subdir(struct inode * new_inode, struct inode * old_inode)
634 
{
635 
        int ino;
636 
        int result;
637 
 
638 
        new_inode->i_count++;
639 
        result = 0;
640 
        for (;;) {
641 
                if (new_inode == old_inode) {
642 
                        result = 1;
643 
                        break;
644 
                }
645 
                if (new_inode->i_dev != old_inode->i_dev)
646 
                        break;
647 
                ino = new_inode->i_ino;
648 
                if (sysv_lookup(new_inode,"..",2,&new_inode))
649 
                        break;
650 
                if (new_inode->i_ino == ino) /* root dir reached ? */
651 
                        break;
652 
        }
653 
        iput(new_inode);
654 
        return result;
655 
}
656 
 
657 
#define PARENT_INO(buffer) \
658 
(((struct sysv_dir_entry *) ((buffer) + 1*SYSV_DIRSIZE))->inode)
659 
 
660 
/*
661 
 * rename uses retrying to avoid race-conditions: at least they should be minimal.
662 
 * it tries to allocate all the blocks, then sanity-checks, and if the sanity-
663 
 * checks fail, it tries to restart itself again. Very practical - no changes
664 
 * are done until we know everything works ok.. and then all the changes can be
665 
 * done in one fell swoop when we have claimed all the buffers needed.
666 
 *
667 
 * Anybody can rename anything with this: the permission checks are left to the
668 
 * higher-level routines.
669 
 */
670 
static int do_sysv_rename(struct inode * old_dir, const char * old_name, int old_len,
671 
        struct inode * new_dir, const char * new_name, int new_len, int must_be_dir)
672 
{
673 
        struct inode * old_inode, * new_inode;
674 
        struct buffer_head * old_bh, * new_bh, * dir_bh;
675 
        struct sysv_dir_entry * old_de, * new_de;
676 
        int retval;
677 
 
678 
        goto start_up;
679 
try_again:
680 
        brelse(old_bh);
681 
        brelse(new_bh);
682 
        brelse(dir_bh);
683 
        iput(old_inode);
684 
        iput(new_inode);
685 
        current->counter = 0;
686 
        schedule();
687 
start_up:
688 
        old_inode = new_inode = NULL;
689 
        old_bh = new_bh = dir_bh = NULL;
690 
        old_bh = sysv_find_entry(old_dir,old_name,old_len,&old_de);
691 
        retval = -ENOENT;
692 
        if (!old_bh)
693 
                goto end_rename;
694 
        old_inode = __iget(old_dir->i_sb, old_de->inode, 0); /* don't cross mnt-points */
695 
        if (!old_inode)
696 
                goto end_rename;
697 
        if (must_be_dir && !S_ISDIR(old_inode->i_mode))
698 
                goto end_rename;
699 
        retval = -EPERM;
700 
        if ((old_dir->i_mode & S_ISVTX) &&
701 
            current->fsuid != old_inode->i_uid &&
702 
            current->fsuid != old_dir->i_uid && !fsuser())
703 
                goto end_rename;
704 
        new_bh = sysv_find_entry(new_dir,new_name,new_len,&new_de);
705 
        if (new_bh) {
706 
                new_inode = __iget(new_dir->i_sb, new_de->inode, 0);
707 
                if (!new_inode) {
708 
                        brelse(new_bh);
709 
                        new_bh = NULL;
710 
                }
711 
        }
712 
        if (new_inode == old_inode) {
713 
                retval = 0;
714 
                goto end_rename;
715 
        }
716 
        if (new_inode && S_ISDIR(new_inode->i_mode)) {
717 
                retval = -EISDIR;
718 
                if (!S_ISDIR(old_inode->i_mode))
719 
                        goto end_rename;
720 
                retval = -EINVAL;
721 
                if (subdir(new_dir, old_inode))
722 
                        goto end_rename;
723 
                retval = -ENOTEMPTY;
724 
                if (!empty_dir(new_inode))
725 
                        goto end_rename;
726 
                retval = -EBUSY;
727 
                if (new_inode->i_count > 1)
728 
                        goto end_rename;
729 
        }
730 
        retval = -EPERM;
731 
        if (new_inode && (new_dir->i_mode & S_ISVTX) &&
732 
            current->fsuid != new_inode->i_uid &&
733 
            current->fsuid != new_dir->i_uid && !fsuser())
734 
                goto end_rename;
735 
        if (S_ISDIR(old_inode->i_mode)) {
736 
                retval = -ENOTDIR;
737 
                if (new_inode && !S_ISDIR(new_inode->i_mode))
738 
                        goto end_rename;
739 
                retval = -EINVAL;
740 
                if (subdir(new_dir, old_inode))
741 
                        goto end_rename;
742 
                retval = -EIO;
743 
                dir_bh = sysv_file_bread(old_inode,0,0);
744 
                if (!dir_bh)
745 
                        goto end_rename;
746 
                if (PARENT_INO(dir_bh->b_data) != old_dir->i_ino)
747 
                        goto end_rename;
748 
                retval = -EMLINK;
749 
                if (!new_inode && new_dir->i_nlink >= new_dir->i_sb->sv_link_max)
750 
                        goto end_rename;
751 
        }
752 
        if (!new_bh) {
753 
                retval = sysv_add_entry(new_dir,new_name,new_len,&new_bh,&new_de);
754 
                if (retval)
755 
                        goto end_rename;
756 
        }
757 
/* sanity checking before doing the rename - avoid races */
758 
        if (new_inode && (new_de->inode != new_inode->i_ino))
759 
                goto try_again;
760 
        if (new_de->inode && !new_inode)
761 
                goto try_again;
762 
        if (old_de->inode != old_inode->i_ino)
763 
                goto try_again;
764 
/* ok, that's it */
765 
        old_de->inode = 0;
766 
        new_de->inode = old_inode->i_ino;
767 
        old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME;
768 
        old_dir->i_dirt = 1;
769 
        new_dir->i_ctime = new_dir->i_mtime = CURRENT_TIME;
770 
        new_dir->i_dirt = 1;
771 
        if (new_inode) {
772 
                new_inode->i_nlink--;
773 
                new_inode->i_ctime = CURRENT_TIME;
774 
                new_inode->i_dirt = 1;
775 
        }
776 
        mark_buffer_dirty(old_bh, 1);
777 
        mark_buffer_dirty(new_bh, 1);
778 
        if (dir_bh) {
779 
                PARENT_INO(dir_bh->b_data) = new_dir->i_ino;
780 
                mark_buffer_dirty(dir_bh, 1);
781 
                old_dir->i_nlink--;
782 
                old_dir->i_dirt = 1;
783 
                if (new_inode) {
784 
                        new_inode->i_nlink--;
785 
                        new_inode->i_dirt = 1;
786 
                } else {
787 
                        new_dir->i_nlink++;
788 
                        new_dir->i_dirt = 1;
789 
                }
790 
        }
791 
        retval = 0;
792 
end_rename:
793 
        brelse(dir_bh);
794 
        brelse(old_bh);
795 
        brelse(new_bh);
796 
        iput(old_inode);
797 
        iput(new_inode);
798 
        iput(old_dir);
799 
        iput(new_dir);
800 
        return retval;
801 
}
802 
 
803 
/*
804 
 * Ok, rename also locks out other renames, as they can change the parent of
805 
 * a directory, and we don't want any races. Other races are checked for by
806 
 * "do_rename()", which restarts if there are inconsistencies.
807 
 *
808 
 * Note that there is no race between different filesystems: it's only within
809 
 * the same device that races occur: many renames can happen at once, as long
810 
 * as they are on different partitions.
811 
 */
812 
int sysv_rename(struct inode * old_dir, const char * old_name, int old_len,
813 
        struct inode * new_dir, const char * new_name, int new_len,
814 
        int must_be_dir)
815 
{
816 
        static struct wait_queue * wait = NULL;
817 
        static int lock = 0;
818 
        int result;
819 
 
820 
        while (lock)
821 
                sleep_on(&wait);
822 
        lock = 1;
823 
        result = do_sysv_rename(old_dir, old_name, old_len,
824 
                new_dir, new_name, new_len, must_be_dir);
825 
        lock = 0;
826 
        wake_up(&wait);
827 
        return result;
828 
}

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