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1/*
2 * linux/fs/sysv/dir.c
3 *
4 * minix/dir.c
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 *
7 * coh/dir.c
8 * Copyright (C) 1993 Pascal Haible, Bruno Haible
9 *
10 * sysv/dir.c
11 * Copyright (C) 1993 Bruno Haible
12 *
13 * SystemV/Coherent directory handling functions
14 */
15
16#include <linux/pagemap.h>
17#include <linux/highmem.h>
18#include <linux/swap.h>
19#include "sysv.h"
20
21static int sysv_readdir(struct file *, struct dir_context *);
22
23const struct file_operations sysv_dir_operations = {
24 .llseek = generic_file_llseek,
25 .read = generic_read_dir,
26 .iterate = sysv_readdir,
27 .fsync = generic_file_fsync,
28};
29
30static inline void dir_put_page(struct page *page)
31{
32 kunmap(page);
33 put_page(page);
34}
35
36static int dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
37{
38 struct address_space *mapping = page->mapping;
39 struct inode *dir = mapping->host;
40 int err = 0;
41
42 block_write_end(NULL, mapping, pos, len, len, page, NULL);
43 if (pos+len > dir->i_size) {
44 i_size_write(dir, pos+len);
45 mark_inode_dirty(dir);
46 }
47 if (IS_DIRSYNC(dir))
48 err = write_one_page(page, 1);
49 else
50 unlock_page(page);
51 return err;
52}
53
54static struct page * dir_get_page(struct inode *dir, unsigned long n)
55{
56 struct address_space *mapping = dir->i_mapping;
57 struct page *page = read_mapping_page(mapping, n, NULL);
58 if (!IS_ERR(page))
59 kmap(page);
60 return page;
61}
62
63static int sysv_readdir(struct file *file, struct dir_context *ctx)
64{
65 unsigned long pos = ctx->pos;
66 struct inode *inode = file_inode(file);
67 struct super_block *sb = inode->i_sb;
68 unsigned long npages = dir_pages(inode);
69 unsigned offset;
70 unsigned long n;
71
72 ctx->pos = pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1);
73 if (pos >= inode->i_size)
74 return 0;
75
76 offset = pos & ~PAGE_MASK;
77 n = pos >> PAGE_SHIFT;
78
79 for ( ; n < npages; n++, offset = 0) {
80 char *kaddr, *limit;
81 struct sysv_dir_entry *de;
82 struct page *page = dir_get_page(inode, n);
83
84 if (IS_ERR(page))
85 continue;
86 kaddr = (char *)page_address(page);
87 de = (struct sysv_dir_entry *)(kaddr+offset);
88 limit = kaddr + PAGE_SIZE - SYSV_DIRSIZE;
89 for ( ;(char*)de <= limit; de++, ctx->pos += sizeof(*de)) {
90 char *name = de->name;
91
92 if (!de->inode)
93 continue;
94
95 if (!dir_emit(ctx, name, strnlen(name,SYSV_NAMELEN),
96 fs16_to_cpu(SYSV_SB(sb), de->inode),
97 DT_UNKNOWN)) {
98 dir_put_page(page);
99 return 0;
100 }
101 }
102 dir_put_page(page);
103 }
104 return 0;
105}
106
107/* compare strings: name[0..len-1] (not zero-terminated) and
108 * buffer[0..] (filled with zeroes up to buffer[0..maxlen-1])
109 */
110static inline int namecompare(int len, int maxlen,
111 const char * name, const char * buffer)
112{
113 if (len < maxlen && buffer[len])
114 return 0;
115 return !memcmp(name, buffer, len);
116}
117
118/*
119 * sysv_find_entry()
120 *
121 * finds an entry in the specified directory with the wanted name. It
122 * returns the cache buffer in which the entry was found, and the entry
123 * itself (as a parameter - res_dir). It does NOT read the inode of the
124 * entry - you'll have to do that yourself if you want to.
125 */
126struct sysv_dir_entry *sysv_find_entry(struct dentry *dentry, struct page **res_page)
127{
128 const char * name = dentry->d_name.name;
129 int namelen = dentry->d_name.len;
130 struct inode * dir = d_inode(dentry->d_parent);
131 unsigned long start, n;
132 unsigned long npages = dir_pages(dir);
133 struct page *page = NULL;
134 struct sysv_dir_entry *de;
135
136 *res_page = NULL;
137
138 start = SYSV_I(dir)->i_dir_start_lookup;
139 if (start >= npages)
140 start = 0;
141 n = start;
142
143 do {
144 char *kaddr;
145 page = dir_get_page(dir, n);
146 if (!IS_ERR(page)) {
147 kaddr = (char*)page_address(page);
148 de = (struct sysv_dir_entry *) kaddr;
149 kaddr += PAGE_SIZE - SYSV_DIRSIZE;
150 for ( ; (char *) de <= kaddr ; de++) {
151 if (!de->inode)
152 continue;
153 if (namecompare(namelen, SYSV_NAMELEN,
154 name, de->name))
155 goto found;
156 }
157 dir_put_page(page);
158 }
159
160 if (++n >= npages)
161 n = 0;
162 } while (n != start);
163
164 return NULL;
165
166found:
167 SYSV_I(dir)->i_dir_start_lookup = n;
168 *res_page = page;
169 return de;
170}
171
172int sysv_add_link(struct dentry *dentry, struct inode *inode)
173{
174 struct inode *dir = d_inode(dentry->d_parent);
175 const char * name = dentry->d_name.name;
176 int namelen = dentry->d_name.len;
177 struct page *page = NULL;
178 struct sysv_dir_entry * de;
179 unsigned long npages = dir_pages(dir);
180 unsigned long n;
181 char *kaddr;
182 loff_t pos;
183 int err;
184
185 /* We take care of directory expansion in the same loop */
186 for (n = 0; n <= npages; n++) {
187 page = dir_get_page(dir, n);
188 err = PTR_ERR(page);
189 if (IS_ERR(page))
190 goto out;
191 kaddr = (char*)page_address(page);
192 de = (struct sysv_dir_entry *)kaddr;
193 kaddr += PAGE_SIZE - SYSV_DIRSIZE;
194 while ((char *)de <= kaddr) {
195 if (!de->inode)
196 goto got_it;
197 err = -EEXIST;
198 if (namecompare(namelen, SYSV_NAMELEN, name, de->name))
199 goto out_page;
200 de++;
201 }
202 dir_put_page(page);
203 }
204 BUG();
205 return -EINVAL;
206
207got_it:
208 pos = page_offset(page) +
209 (char*)de - (char*)page_address(page);
210 lock_page(page);
211 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
212 if (err)
213 goto out_unlock;
214 memcpy (de->name, name, namelen);
215 memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2);
216 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
217 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
218 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
219 mark_inode_dirty(dir);
220out_page:
221 dir_put_page(page);
222out:
223 return err;
224out_unlock:
225 unlock_page(page);
226 goto out_page;
227}
228
229int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page)
230{
231 struct inode *inode = page->mapping->host;
232 char *kaddr = (char*)page_address(page);
233 loff_t pos = page_offset(page) + (char *)de - kaddr;
234 int err;
235
236 lock_page(page);
237 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
238 BUG_ON(err);
239 de->inode = 0;
240 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
241 dir_put_page(page);
242 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
243 mark_inode_dirty(inode);
244 return err;
245}
246
247int sysv_make_empty(struct inode *inode, struct inode *dir)
248{
249 struct page *page = grab_cache_page(inode->i_mapping, 0);
250 struct sysv_dir_entry * de;
251 char *base;
252 int err;
253
254 if (!page)
255 return -ENOMEM;
256 err = sysv_prepare_chunk(page, 0, 2 * SYSV_DIRSIZE);
257 if (err) {
258 unlock_page(page);
259 goto fail;
260 }
261 kmap(page);
262
263 base = (char*)page_address(page);
264 memset(base, 0, PAGE_SIZE);
265
266 de = (struct sysv_dir_entry *) base;
267 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
268 strcpy(de->name,".");
269 de++;
270 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), dir->i_ino);
271 strcpy(de->name,"..");
272
273 kunmap(page);
274 err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
275fail:
276 put_page(page);
277 return err;
278}
279
280/*
281 * routine to check that the specified directory is empty (for rmdir)
282 */
283int sysv_empty_dir(struct inode * inode)
284{
285 struct super_block *sb = inode->i_sb;
286 struct page *page = NULL;
287 unsigned long i, npages = dir_pages(inode);
288
289 for (i = 0; i < npages; i++) {
290 char *kaddr;
291 struct sysv_dir_entry * de;
292 page = dir_get_page(inode, i);
293
294 if (IS_ERR(page))
295 continue;
296
297 kaddr = (char *)page_address(page);
298 de = (struct sysv_dir_entry *)kaddr;
299 kaddr += PAGE_SIZE-SYSV_DIRSIZE;
300
301 for ( ;(char *)de <= kaddr; de++) {
302 if (!de->inode)
303 continue;
304 /* check for . and .. */
305 if (de->name[0] != '.')
306 goto not_empty;
307 if (!de->name[1]) {
308 if (de->inode == cpu_to_fs16(SYSV_SB(sb),
309 inode->i_ino))
310 continue;
311 goto not_empty;
312 }
313 if (de->name[1] != '.' || de->name[2])
314 goto not_empty;
315 }
316 dir_put_page(page);
317 }
318 return 1;
319
320not_empty:
321 dir_put_page(page);
322 return 0;
323}
324
325/* Releases the page */
326void sysv_set_link(struct sysv_dir_entry *de, struct page *page,
327 struct inode *inode)
328{
329 struct inode *dir = page->mapping->host;
330 loff_t pos = page_offset(page) +
331 (char *)de-(char*)page_address(page);
332 int err;
333
334 lock_page(page);
335 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
336 BUG_ON(err);
337 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
338 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
339 dir_put_page(page);
340 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
341 mark_inode_dirty(dir);
342}
343
344struct sysv_dir_entry * sysv_dotdot (struct inode *dir, struct page **p)
345{
346 struct page *page = dir_get_page(dir, 0);
347 struct sysv_dir_entry *de = NULL;
348
349 if (!IS_ERR(page)) {
350 de = (struct sysv_dir_entry*) page_address(page) + 1;
351 *p = page;
352 }
353 return de;
354}
355
356ino_t sysv_inode_by_name(struct dentry *dentry)
357{
358 struct page *page;
359 struct sysv_dir_entry *de = sysv_find_entry (dentry, &page);
360 ino_t res = 0;
361
362 if (de) {
363 res = fs16_to_cpu(SYSV_SB(dentry->d_sb), de->inode);
364 dir_put_page(page);
365 }
366 return res;
367}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/sysv/dir.c
4 *
5 * minix/dir.c
6 * Copyright (C) 1991, 1992 Linus Torvalds
7 *
8 * coh/dir.c
9 * Copyright (C) 1993 Pascal Haible, Bruno Haible
10 *
11 * sysv/dir.c
12 * Copyright (C) 1993 Bruno Haible
13 *
14 * SystemV/Coherent directory handling functions
15 */
16
17#include <linux/pagemap.h>
18#include <linux/highmem.h>
19#include <linux/swap.h>
20#include "sysv.h"
21
22static int sysv_readdir(struct file *, struct dir_context *);
23
24const struct file_operations sysv_dir_operations = {
25 .llseek = generic_file_llseek,
26 .read = generic_read_dir,
27 .iterate_shared = sysv_readdir,
28 .fsync = generic_file_fsync,
29};
30
31static inline void dir_put_page(struct page *page)
32{
33 kunmap(page);
34 put_page(page);
35}
36
37static int dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
38{
39 struct address_space *mapping = page->mapping;
40 struct inode *dir = mapping->host;
41 int err = 0;
42
43 block_write_end(NULL, mapping, pos, len, len, page, NULL);
44 if (pos+len > dir->i_size) {
45 i_size_write(dir, pos+len);
46 mark_inode_dirty(dir);
47 }
48 if (IS_DIRSYNC(dir))
49 err = write_one_page(page);
50 else
51 unlock_page(page);
52 return err;
53}
54
55static struct page * dir_get_page(struct inode *dir, unsigned long n)
56{
57 struct address_space *mapping = dir->i_mapping;
58 struct page *page = read_mapping_page(mapping, n, NULL);
59 if (!IS_ERR(page))
60 kmap(page);
61 return page;
62}
63
64static int sysv_readdir(struct file *file, struct dir_context *ctx)
65{
66 unsigned long pos = ctx->pos;
67 struct inode *inode = file_inode(file);
68 struct super_block *sb = inode->i_sb;
69 unsigned long npages = dir_pages(inode);
70 unsigned offset;
71 unsigned long n;
72
73 ctx->pos = pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1);
74 if (pos >= inode->i_size)
75 return 0;
76
77 offset = pos & ~PAGE_MASK;
78 n = pos >> PAGE_SHIFT;
79
80 for ( ; n < npages; n++, offset = 0) {
81 char *kaddr, *limit;
82 struct sysv_dir_entry *de;
83 struct page *page = dir_get_page(inode, n);
84
85 if (IS_ERR(page))
86 continue;
87 kaddr = (char *)page_address(page);
88 de = (struct sysv_dir_entry *)(kaddr+offset);
89 limit = kaddr + PAGE_SIZE - SYSV_DIRSIZE;
90 for ( ;(char*)de <= limit; de++, ctx->pos += sizeof(*de)) {
91 char *name = de->name;
92
93 if (!de->inode)
94 continue;
95
96 if (!dir_emit(ctx, name, strnlen(name,SYSV_NAMELEN),
97 fs16_to_cpu(SYSV_SB(sb), de->inode),
98 DT_UNKNOWN)) {
99 dir_put_page(page);
100 return 0;
101 }
102 }
103 dir_put_page(page);
104 }
105 return 0;
106}
107
108/* compare strings: name[0..len-1] (not zero-terminated) and
109 * buffer[0..] (filled with zeroes up to buffer[0..maxlen-1])
110 */
111static inline int namecompare(int len, int maxlen,
112 const char * name, const char * buffer)
113{
114 if (len < maxlen && buffer[len])
115 return 0;
116 return !memcmp(name, buffer, len);
117}
118
119/*
120 * sysv_find_entry()
121 *
122 * finds an entry in the specified directory with the wanted name. It
123 * returns the cache buffer in which the entry was found, and the entry
124 * itself (as a parameter - res_dir). It does NOT read the inode of the
125 * entry - you'll have to do that yourself if you want to.
126 */
127struct sysv_dir_entry *sysv_find_entry(struct dentry *dentry, struct page **res_page)
128{
129 const char * name = dentry->d_name.name;
130 int namelen = dentry->d_name.len;
131 struct inode * dir = d_inode(dentry->d_parent);
132 unsigned long start, n;
133 unsigned long npages = dir_pages(dir);
134 struct page *page = NULL;
135 struct sysv_dir_entry *de;
136
137 *res_page = NULL;
138
139 start = SYSV_I(dir)->i_dir_start_lookup;
140 if (start >= npages)
141 start = 0;
142 n = start;
143
144 do {
145 char *kaddr;
146 page = dir_get_page(dir, n);
147 if (!IS_ERR(page)) {
148 kaddr = (char*)page_address(page);
149 de = (struct sysv_dir_entry *) kaddr;
150 kaddr += PAGE_SIZE - SYSV_DIRSIZE;
151 for ( ; (char *) de <= kaddr ; de++) {
152 if (!de->inode)
153 continue;
154 if (namecompare(namelen, SYSV_NAMELEN,
155 name, de->name))
156 goto found;
157 }
158 dir_put_page(page);
159 }
160
161 if (++n >= npages)
162 n = 0;
163 } while (n != start);
164
165 return NULL;
166
167found:
168 SYSV_I(dir)->i_dir_start_lookup = n;
169 *res_page = page;
170 return de;
171}
172
173int sysv_add_link(struct dentry *dentry, struct inode *inode)
174{
175 struct inode *dir = d_inode(dentry->d_parent);
176 const char * name = dentry->d_name.name;
177 int namelen = dentry->d_name.len;
178 struct page *page = NULL;
179 struct sysv_dir_entry * de;
180 unsigned long npages = dir_pages(dir);
181 unsigned long n;
182 char *kaddr;
183 loff_t pos;
184 int err;
185
186 /* We take care of directory expansion in the same loop */
187 for (n = 0; n <= npages; n++) {
188 page = dir_get_page(dir, n);
189 err = PTR_ERR(page);
190 if (IS_ERR(page))
191 goto out;
192 kaddr = (char*)page_address(page);
193 de = (struct sysv_dir_entry *)kaddr;
194 kaddr += PAGE_SIZE - SYSV_DIRSIZE;
195 while ((char *)de <= kaddr) {
196 if (!de->inode)
197 goto got_it;
198 err = -EEXIST;
199 if (namecompare(namelen, SYSV_NAMELEN, name, de->name))
200 goto out_page;
201 de++;
202 }
203 dir_put_page(page);
204 }
205 BUG();
206 return -EINVAL;
207
208got_it:
209 pos = page_offset(page) +
210 (char*)de - (char*)page_address(page);
211 lock_page(page);
212 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
213 if (err)
214 goto out_unlock;
215 memcpy (de->name, name, namelen);
216 memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2);
217 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
218 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
219 dir->i_mtime = dir->i_ctime = current_time(dir);
220 mark_inode_dirty(dir);
221out_page:
222 dir_put_page(page);
223out:
224 return err;
225out_unlock:
226 unlock_page(page);
227 goto out_page;
228}
229
230int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page)
231{
232 struct inode *inode = page->mapping->host;
233 char *kaddr = (char*)page_address(page);
234 loff_t pos = page_offset(page) + (char *)de - kaddr;
235 int err;
236
237 lock_page(page);
238 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
239 BUG_ON(err);
240 de->inode = 0;
241 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
242 dir_put_page(page);
243 inode->i_ctime = inode->i_mtime = current_time(inode);
244 mark_inode_dirty(inode);
245 return err;
246}
247
248int sysv_make_empty(struct inode *inode, struct inode *dir)
249{
250 struct page *page = grab_cache_page(inode->i_mapping, 0);
251 struct sysv_dir_entry * de;
252 char *base;
253 int err;
254
255 if (!page)
256 return -ENOMEM;
257 err = sysv_prepare_chunk(page, 0, 2 * SYSV_DIRSIZE);
258 if (err) {
259 unlock_page(page);
260 goto fail;
261 }
262 kmap(page);
263
264 base = (char*)page_address(page);
265 memset(base, 0, PAGE_SIZE);
266
267 de = (struct sysv_dir_entry *) base;
268 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
269 strcpy(de->name,".");
270 de++;
271 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), dir->i_ino);
272 strcpy(de->name,"..");
273
274 kunmap(page);
275 err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
276fail:
277 put_page(page);
278 return err;
279}
280
281/*
282 * routine to check that the specified directory is empty (for rmdir)
283 */
284int sysv_empty_dir(struct inode * inode)
285{
286 struct super_block *sb = inode->i_sb;
287 struct page *page = NULL;
288 unsigned long i, npages = dir_pages(inode);
289
290 for (i = 0; i < npages; i++) {
291 char *kaddr;
292 struct sysv_dir_entry * de;
293 page = dir_get_page(inode, i);
294
295 if (IS_ERR(page))
296 continue;
297
298 kaddr = (char *)page_address(page);
299 de = (struct sysv_dir_entry *)kaddr;
300 kaddr += PAGE_SIZE-SYSV_DIRSIZE;
301
302 for ( ;(char *)de <= kaddr; de++) {
303 if (!de->inode)
304 continue;
305 /* check for . and .. */
306 if (de->name[0] != '.')
307 goto not_empty;
308 if (!de->name[1]) {
309 if (de->inode == cpu_to_fs16(SYSV_SB(sb),
310 inode->i_ino))
311 continue;
312 goto not_empty;
313 }
314 if (de->name[1] != '.' || de->name[2])
315 goto not_empty;
316 }
317 dir_put_page(page);
318 }
319 return 1;
320
321not_empty:
322 dir_put_page(page);
323 return 0;
324}
325
326/* Releases the page */
327void sysv_set_link(struct sysv_dir_entry *de, struct page *page,
328 struct inode *inode)
329{
330 struct inode *dir = page->mapping->host;
331 loff_t pos = page_offset(page) +
332 (char *)de-(char*)page_address(page);
333 int err;
334
335 lock_page(page);
336 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
337 BUG_ON(err);
338 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
339 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
340 dir_put_page(page);
341 dir->i_mtime = dir->i_ctime = current_time(dir);
342 mark_inode_dirty(dir);
343}
344
345struct sysv_dir_entry * sysv_dotdot (struct inode *dir, struct page **p)
346{
347 struct page *page = dir_get_page(dir, 0);
348 struct sysv_dir_entry *de = NULL;
349
350 if (!IS_ERR(page)) {
351 de = (struct sysv_dir_entry*) page_address(page) + 1;
352 *p = page;
353 }
354 return de;
355}
356
357ino_t sysv_inode_by_name(struct dentry *dentry)
358{
359 struct page *page;
360 struct sysv_dir_entry *de = sysv_find_entry (dentry, &page);
361 ino_t res = 0;
362
363 if (de) {
364 res = fs16_to_cpu(SYSV_SB(dentry->d_sb), de->inode);
365 dir_put_page(page);
366 }
367 return res;
368}