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1 /*
2 * linux/fs/ext2/dir.c
3 *
4 * Copyright (C) 1992, 1993, 1994 Remy Card (card@masi.ibp.fr)
5 * Laboratoire MASI - Institut Blaise Pascal
6 * Universite Pierre et Marie Curie (Paris VI)
7 *
8 * from
9 *
10 * linux/fs/minix/dir.c
11 *
12 * Copyright (C) 1991, 1992 Linus Torvalds
13 *
14 * ext2 directory handling functions
15 */
16
17 #include <asm/segment.h>
18
19 #include <linux/errno.h>
20 #include <linux/fs.h>
21 #include <linux/ext2_fs.h>
22 #include <linux/sched.h>
23 #include <linux/stat.h>
24
25 #define NAME_OFFSET(de) ((int) ((de)->d_name - (char *) (de)))
26 #define ROUND_UP(x) (((x)+3) & ~3)
27
28 static int ext2_dir_read (struct inode * inode, struct file * filp,
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*/
29 char * buf, int count)
30 {
31 return -EISDIR;
32 }
33
34 static int ext2_readdir (struct inode *, struct file *, struct dirent *, int);
35
36 static struct file_operations ext2_dir_operations = {
37 NULL, /* lseek - default */
38 ext2_dir_read, /* read */
39 NULL, /* write - bad */
40 ext2_readdir, /* readdir */
41 NULL, /* select - default */
42 ext2_ioctl, /* ioctl */
43 NULL, /* mmap */
44 NULL, /* no special open code */
45 NULL, /* no special release code */
46 file_fsync, /* fsync */
47 NULL, /* fasync */
48 NULL, /* check_media_change */
49 NULL /* revalidate */
50 };
51
52 /*
53 * directories can handle most operations...
54 */
55 struct inode_operations ext2_dir_inode_operations = {
56 &ext2_dir_operations, /* default directory file-ops */
57 ext2_create, /* create */
58 ext2_lookup, /* lookup */
59 ext2_link, /* link */
60 ext2_unlink, /* unlink */
61 ext2_symlink, /* symlink */
62 ext2_mkdir, /* mkdir */
63 ext2_rmdir, /* rmdir */
64 ext2_mknod, /* mknod */
65 ext2_rename, /* rename */
66 NULL, /* readlink */
67 NULL, /* follow_link */
68 NULL, /* bmap */
69 ext2_truncate, /* truncate */
70 ext2_permission, /* permission */
71 NULL /* smap */
72 };
73
74 int ext2_check_dir_entry (char * function, struct inode * dir,
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75 struct ext2_dir_entry * de, struct buffer_head * bh,
76 unsigned long offset)
77 {
78 char * error_msg = NULL;
79
80 if (de->rec_len < EXT2_DIR_REC_LEN(1))
81 error_msg = "rec_len is smaller than minimal";
82 else if (de->rec_len % 4 != 0)
83 error_msg = "rec_len % 4 != 0";
84 else if (de->rec_len < EXT2_DIR_REC_LEN(de->name_len))
85 error_msg = "rec_len is too small for name_len";
86 else if (dir && ((char *) de - bh->b_data) + de->rec_len >
87 dir->i_sb->s_blocksize)
88 error_msg = "directory entry across blocks";
89 else if (dir && de->inode > dir->i_sb->u.ext2_sb.s_es->s_inodes_count)
90 error_msg = "inode out of bounds";
91
92 if (error_msg != NULL)
93 ext2_error (dir->i_sb, function, "bad directory entry: %s\n"
94 "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
95 error_msg, offset, (unsigned long) de->inode, de->rec_len,
96 de->name_len);
97 return error_msg == NULL ? 1 : 0;
98 }
99
100 static int ext2_readdir (struct inode * inode, struct file * filp,
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101 struct dirent * dirent, int count)
102 {
103 unsigned long offset, blk;
104 int i, num, stored, dlen;
105 struct buffer_head * bh, * tmp, * bha[16];
106 struct ext2_dir_entry * de;
107 struct super_block * sb;
108 int err, version;
109
110 if (!inode || !S_ISDIR(inode->i_mode))
111 return -EBADF;
112 sb = inode->i_sb;
113
114 stored = 0;
115 bh = NULL;
116 offset = filp->f_pos & (sb->s_blocksize - 1);
117
118 while (count > 0 && !stored && filp->f_pos < inode->i_size) {
119 blk = (filp->f_pos) >> EXT2_BLOCK_SIZE_BITS(sb);
120 bh = ext2_bread (inode, blk, 0, &err);
121 if (!bh) {
122 filp->f_pos += sb->s_blocksize - offset;
123 continue;
124 }
125
126 /*
127 * Do the readahead
128 */
129 if (!offset) {
130 for (i = 16 >> (EXT2_BLOCK_SIZE_BITS(sb) - 9), num = 0;
131 i > 0; i--) {
132 tmp = ext2_getblk (inode, ++blk, 0, &err);
133 if (tmp && !tmp->b_uptodate && !tmp->b_lock)
134 bha[num++] = tmp;
135 else
136 brelse (tmp);
137 }
138 if (num) {
139 ll_rw_block (READA, num, bha);
140 for (i = 0; i < num; i++)
141 brelse (bha[i]);
142 }
143 }
144
145 revalidate:
146 /* If the dir block has changed since the last call to
147 * readdir(2), then we might be pointing to an invalid
148 * dirent right now. Scan from the start of the block
149 * to make sure. */
150 if (filp->f_version != inode->i_version) {
151 for (i = 0; i < sb->s_blocksize && i < offset; ) {
152 de = (struct ext2_dir_entry *)
153 (bh->b_data + i);
154 /* It's too expensive to do a full
155 * dirent test each time round this
156 * loop, but we do have to test at
157 * least that it is non-zero. A
158 * failure will be detected in the
159 * dirent test below. */
160 if (de->rec_len < EXT2_DIR_REC_LEN(1))
161 break;
162 i += de->rec_len;
163 }
164 offset = i;
165 filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
166 | offset;
167 filp->f_version = inode->i_version;
168 }
169
170 while (count > 0 && filp->f_pos < inode->i_size
171 && offset < sb->s_blocksize) {
172 de = (struct ext2_dir_entry *) (bh->b_data + offset);
173 if (!ext2_check_dir_entry ("ext2_readdir", inode, de,
174 bh, offset)) {
175 /* On error, skip the f_pos to the
176 next block. */
177 filp->f_pos = (filp->f_pos & (sb->s_blocksize - 1))
178 + sb->s_blocksize;
179 brelse (bh);
180 return stored;
181 }
182 if (de->inode) {
183 dlen = ROUND_UP(NAME_OFFSET(dirent)
184 + de->name_len + 1);
185 /* Old libc libraries always use a
186 count of 1. */
187 if (count == 1 && !stored)
188 count = dlen;
189 if (count < dlen) {
190 count = 0;
191 break;
192 }
193
194 /* We might block in the next section
195 * if the data destination is
196 * currently swapped out. So, use a
197 * version stamp to detect whether or
198 * not the directory has been modified
199 * during the copy operation. */
200 version = inode->i_version;
201 i = de->name_len;
202 memcpy_tofs (dirent->d_name, de->name, i);
203 put_fs_long (de->inode, &dirent->d_ino);
204 put_fs_byte (0, dirent->d_name + i);
205 put_fs_word (i, &dirent->d_reclen);
206 put_fs_long (dlen, &dirent->d_off);
207 if (version != inode->i_version)
208 goto revalidate;
209 dcache_add(inode, de->name, de->name_len,
210 de->inode);
211
212 stored += dlen;
213 count -= dlen;
214 ((char *) dirent) += dlen;
215 }
216 offset += de->rec_len;
217 filp->f_pos += de->rec_len;
218 }
219 offset = 0;
220 brelse (bh);
221 }
222 if (!IS_RDONLY(inode)) {
223 inode->i_atime = CURRENT_TIME;
224 inode->i_dirt = 1;
225 }
226 return stored;
227 }
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*/