1// SPDX-License-Identifier: GPL-2.0
2/*
3 *	fs/bfs/dir.c
4 *	BFS directory operations.
5 *	Copyright (C) 1999-2018  Tigran Aivazian <aivazian.tigran@gmail.com>
6 *  Made endianness-clean by Andrew Stribblehill <ads@wompom.org> 2005
7 */
8
9#include <linux/time.h>
10#include <linux/string.h>
11#include <linux/fs.h>
12#include <linux/buffer_head.h>
13#include <linux/sched.h>
14#include "bfs.h"
15
16#undef DEBUG
17
18#ifdef DEBUG
19#define dprintf(x...)	printf(x)
20#else
21#define dprintf(x...)
22#endif
23
24static int bfs_add_entry(struct inode *dir, const struct qstr *child, int ino);
25static struct buffer_head *bfs_find_entry(struct inode *dir,
26				const struct qstr *child,
27				struct bfs_dirent **res_dir);
28
29static int bfs_readdir(struct file *f, struct dir_context *ctx)
30{
31	struct inode *dir = file_inode(f);
32	struct buffer_head *bh;
33	struct bfs_dirent *de;
34	unsigned int offset;
35	int block;
36
37	if (ctx->pos & (BFS_DIRENT_SIZE - 1)) {
38		printf("Bad f_pos=%08lx for %s:%08lx\n",
39					(unsigned long)ctx->pos,
40					dir->i_sb->s_id, dir->i_ino);
41		return -EINVAL;
42	}
43
44	while (ctx->pos < dir->i_size) {
45		offset = ctx->pos & (BFS_BSIZE - 1);
46		block = BFS_I(dir)->i_sblock + (ctx->pos >> BFS_BSIZE_BITS);
47		bh = sb_bread(dir->i_sb, block);
48		if (!bh) {
49			ctx->pos += BFS_BSIZE - offset;
50			continue;
51		}
52		do {
53			de = (struct bfs_dirent *)(bh->b_data + offset);
54			if (de->ino) {
55				int size = strnlen(de->name, BFS_NAMELEN);
56				if (!dir_emit(ctx, de->name, size,
57						le16_to_cpu(de->ino),
58						DT_UNKNOWN)) {
59					brelse(bh);
60					return 0;
61				}
62			}
63			offset += BFS_DIRENT_SIZE;
64			ctx->pos += BFS_DIRENT_SIZE;
65		} while ((offset < BFS_BSIZE) && (ctx->pos < dir->i_size));
66		brelse(bh);
67	}
68	return 0;
69}
70
71const struct file_operations bfs_dir_operations = {
72	.read		= generic_read_dir,
73	.iterate_shared	= bfs_readdir,
74	.fsync		= generic_file_fsync,
75	.llseek		= generic_file_llseek,
76};
77
78static int bfs_create(struct mnt_idmap *idmap, struct inode *dir,
79		      struct dentry *dentry, umode_t mode, bool excl)
80{
81	int err;
82	struct inode *inode;
83	struct super_block *s = dir->i_sb;
84	struct bfs_sb_info *info = BFS_SB(s);
85	unsigned long ino;
86
87	inode = new_inode(s);
88	if (!inode)
89		return -ENOMEM;
90	mutex_lock(&info->bfs_lock);
91	ino = find_first_zero_bit(info->si_imap, info->si_lasti + 1);
92	if (ino > info->si_lasti) {
93		mutex_unlock(&info->bfs_lock);
94		iput(inode);
95		return -ENOSPC;
96	}
97	set_bit(ino, info->si_imap);
98	info->si_freei--;
99	inode_init_owner(&nop_mnt_idmap, inode, dir, mode);
100	simple_inode_init_ts(inode);
101	inode->i_blocks = 0;
102	inode->i_op = &bfs_file_inops;
103	inode->i_fop = &bfs_file_operations;
104	inode->i_mapping->a_ops = &bfs_aops;
105	inode->i_ino = ino;
106	BFS_I(inode)->i_dsk_ino = ino;
107	BFS_I(inode)->i_sblock = 0;
108	BFS_I(inode)->i_eblock = 0;
109	insert_inode_hash(inode);
110        mark_inode_dirty(inode);
111	bfs_dump_imap("create", s);
112
113	err = bfs_add_entry(dir, &dentry->d_name, inode->i_ino);
114	if (err) {
115		inode_dec_link_count(inode);
116		mutex_unlock(&info->bfs_lock);
117		iput(inode);
118		return err;
119	}
120	mutex_unlock(&info->bfs_lock);
121	d_instantiate(dentry, inode);
122	return 0;
123}
124
125static struct dentry *bfs_lookup(struct inode *dir, struct dentry *dentry,
126						unsigned int flags)
127{
128	struct inode *inode = NULL;
129	struct buffer_head *bh;
130	struct bfs_dirent *de;
131	struct bfs_sb_info *info = BFS_SB(dir->i_sb);
132
133	if (dentry->d_name.len > BFS_NAMELEN)
134		return ERR_PTR(-ENAMETOOLONG);
135
136	mutex_lock(&info->bfs_lock);
137	bh = bfs_find_entry(dir, &dentry->d_name, &de);
138	if (bh) {
139		unsigned long ino = (unsigned long)le16_to_cpu(de->ino);
140		brelse(bh);
141		inode = bfs_iget(dir->i_sb, ino);
142	}
143	mutex_unlock(&info->bfs_lock);
144	return d_splice_alias(inode, dentry);
145}
146
147static int bfs_link(struct dentry *old, struct inode *dir,
148						struct dentry *new)
149{
150	struct inode *inode = d_inode(old);
151	struct bfs_sb_info *info = BFS_SB(inode->i_sb);
152	int err;
153
154	mutex_lock(&info->bfs_lock);
155	err = bfs_add_entry(dir, &new->d_name, inode->i_ino);
156	if (err) {
157		mutex_unlock(&info->bfs_lock);
158		return err;
159	}
160	inc_nlink(inode);
161	inode_set_ctime_current(inode);
162	mark_inode_dirty(inode);
163	ihold(inode);
164	d_instantiate(new, inode);
165	mutex_unlock(&info->bfs_lock);
166	return 0;
167}
168
169static int bfs_unlink(struct inode *dir, struct dentry *dentry)
170{
171	int error = -ENOENT;
172	struct inode *inode = d_inode(dentry);
173	struct buffer_head *bh;
174	struct bfs_dirent *de;
175	struct bfs_sb_info *info = BFS_SB(inode->i_sb);
176
177	mutex_lock(&info->bfs_lock);
178	bh = bfs_find_entry(dir, &dentry->d_name, &de);
179	if (!bh || (le16_to_cpu(de->ino) != inode->i_ino))
180		goto out_brelse;
181
182	if (!inode->i_nlink) {
183		printf("unlinking non-existent file %s:%lu (nlink=%d)\n",
184					inode->i_sb->s_id, inode->i_ino,
185					inode->i_nlink);
186		set_nlink(inode, 1);
187	}
188	de->ino = 0;
189	mark_buffer_dirty_inode(bh, dir);
190	inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
191	mark_inode_dirty(dir);
192	inode_set_ctime_to_ts(inode, inode_get_ctime(dir));
193	inode_dec_link_count(inode);
194	error = 0;
195
196out_brelse:
197	brelse(bh);
198	mutex_unlock(&info->bfs_lock);
199	return error;
200}
201
202static int bfs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
203		      struct dentry *old_dentry, struct inode *new_dir,
204		      struct dentry *new_dentry, unsigned int flags)
205{
206	struct inode *old_inode, *new_inode;
207	struct buffer_head *old_bh, *new_bh;
208	struct bfs_dirent *old_de, *new_de;
209	struct bfs_sb_info *info;
210	int error = -ENOENT;
211
212	if (flags & ~RENAME_NOREPLACE)
213		return -EINVAL;
214
215	old_bh = new_bh = NULL;
216	old_inode = d_inode(old_dentry);
217	if (S_ISDIR(old_inode->i_mode))
218		return -EINVAL;
219
220	info = BFS_SB(old_inode->i_sb);
221
222	mutex_lock(&info->bfs_lock);
223	old_bh = bfs_find_entry(old_dir, &old_dentry->d_name, &old_de);
224
225	if (!old_bh || (le16_to_cpu(old_de->ino) != old_inode->i_ino))
226		goto end_rename;
227
228	error = -EPERM;
229	new_inode = d_inode(new_dentry);
230	new_bh = bfs_find_entry(new_dir, &new_dentry->d_name, &new_de);
231
232	if (new_bh && !new_inode) {
233		brelse(new_bh);
234		new_bh = NULL;
235	}
236	if (!new_bh) {
237		error = bfs_add_entry(new_dir, &new_dentry->d_name,
238					old_inode->i_ino);
239		if (error)
240			goto end_rename;
241	}
242	old_de->ino = 0;
243	inode_set_mtime_to_ts(old_dir, inode_set_ctime_current(old_dir));
244	mark_inode_dirty(old_dir);
245	if (new_inode) {
246		inode_set_ctime_current(new_inode);
247		inode_dec_link_count(new_inode);
248	}
249	mark_buffer_dirty_inode(old_bh, old_dir);
250	error = 0;
251
252end_rename:
253	mutex_unlock(&info->bfs_lock);
254	brelse(old_bh);
255	brelse(new_bh);
256	return error;
257}
258
259const struct inode_operations bfs_dir_inops = {
260	.create			= bfs_create,
261	.lookup			= bfs_lookup,
262	.link			= bfs_link,
263	.unlink			= bfs_unlink,
264	.rename			= bfs_rename,
265};
266
267static int bfs_add_entry(struct inode *dir, const struct qstr *child, int ino)
268{
269	const unsigned char *name = child->name;
270	int namelen = child->len;
271	struct buffer_head *bh;
272	struct bfs_dirent *de;
273	int block, sblock, eblock, off, pos;
274	int i;
275
276	dprintf("name=%s, namelen=%d\n", name, namelen);
277
278	sblock = BFS_I(dir)->i_sblock;
279	eblock = BFS_I(dir)->i_eblock;
280	for (block = sblock; block <= eblock; block++) {
281		bh = sb_bread(dir->i_sb, block);
282		if (!bh)
283			return -EIO;
284		for (off = 0; off < BFS_BSIZE; off += BFS_DIRENT_SIZE) {
285			de = (struct bfs_dirent *)(bh->b_data + off);
286			if (!de->ino) {
287				pos = (block - sblock) * BFS_BSIZE + off;
288				if (pos >= dir->i_size) {
289					dir->i_size += BFS_DIRENT_SIZE;
290					inode_set_ctime_current(dir);
291				}
292				inode_set_mtime_to_ts(dir,
293						      inode_set_ctime_current(dir));
294				mark_inode_dirty(dir);
295				de->ino = cpu_to_le16((u16)ino);
296				for (i = 0; i < BFS_NAMELEN; i++)
297					de->name[i] =
298						(i < namelen) ? name[i] : 0;
299				mark_buffer_dirty_inode(bh, dir);
300				brelse(bh);
301				return 0;
302			}
303		}
304		brelse(bh);
305	}
306	return -ENOSPC;
307}
308
309static inline int bfs_namecmp(int len, const unsigned char *name,
310							const char *buffer)
311{
312	if ((len < BFS_NAMELEN) && buffer[len])
313		return 0;
314	return !memcmp(name, buffer, len);
315}
316
317static struct buffer_head *bfs_find_entry(struct inode *dir,
318			const struct qstr *child,
319			struct bfs_dirent **res_dir)
320{
321	unsigned long block = 0, offset = 0;
322	struct buffer_head *bh = NULL;
323	struct bfs_dirent *de;
324	const unsigned char *name = child->name;
325	int namelen = child->len;
326
327	*res_dir = NULL;
328	if (namelen > BFS_NAMELEN)
329		return NULL;
330
331	while (block * BFS_BSIZE + offset < dir->i_size) {
332		if (!bh) {
333			bh = sb_bread(dir->i_sb, BFS_I(dir)->i_sblock + block);
334			if (!bh) {
335				block++;
336				continue;
337			}
338		}
339		de = (struct bfs_dirent *)(bh->b_data + offset);
340		offset += BFS_DIRENT_SIZE;
341		if (le16_to_cpu(de->ino) &&
342				bfs_namecmp(namelen, name, de->name)) {
343			*res_dir = de;
344			return bh;
345		}
346		if (offset < bh->b_size)
347			continue;
348		brelse(bh);
349		bh = NULL;
350		offset = 0;
351		block++;
352	}
353	brelse(bh);
354	return NULL;
355}
356