1 /*
2 * dir_iterate.c --- ext2fs directory iteration operations
3 *
4 * Copyright (C) 1993, 1994, 1994, 1995, 1996, 1997 Theodore Ts'o.
5 *
6 * %Begin-Header%
7 * This file may be redistributed under the terms of the GNU Public
8 * License.
9 * %End-Header%
10 */
11
12 #include <stdio.h>
13 #include <string.h>
14 #if HAVE_UNISTD_H
15 #include <unistd.h>
16 #endif
17 #if HAVE_ERRNO_H
18 #include <errno.h>
19 #endif
20
21 #include "ext2_fs.h"
22 #include "ext2fsP.h"
23
24 #define EXT4_MAX_REC_LEN ((1<<16)-1)
25
ext2fs_get_rec_len(ext2_filsys fs,struct ext2_dir_entry * dirent,unsigned int * rec_len)26 errcode_t ext2fs_get_rec_len(ext2_filsys fs,
27 struct ext2_dir_entry *dirent,
28 unsigned int *rec_len)
29 {
30 unsigned int len = dirent->rec_len;
31
32 if (len == EXT4_MAX_REC_LEN || len == 0)
33 *rec_len = fs->blocksize;
34 else
35 *rec_len = (len & 65532) | ((len & 3) << 16);
36 return 0;
37 }
38
ext2fs_set_rec_len(ext2_filsys fs,unsigned int len,struct ext2_dir_entry * dirent)39 errcode_t ext2fs_set_rec_len(ext2_filsys fs,
40 unsigned int len,
41 struct ext2_dir_entry *dirent)
42 {
43 if ((len > fs->blocksize) || (fs->blocksize > (1 << 18)) || (len & 3))
44 return EINVAL;
45 if (len < 65536) {
46 dirent->rec_len = len;
47 return 0;
48 }
49 if (len == fs->blocksize) {
50 if (fs->blocksize == 65536)
51 dirent->rec_len = EXT4_MAX_REC_LEN;
52 else
53 dirent->rec_len = 0;
54 } else
55 dirent->rec_len = (len & 65532) | ((len >> 16) & 3);
56 return 0;
57 }
58
59 /*
60 * This function checks to see whether or not a potential deleted
61 * directory entry looks valid. What we do is check the deleted entry
62 * and each successive entry to make sure that they all look valid and
63 * that the last deleted entry ends at the beginning of the next
64 * undeleted entry. Returns 1 if the deleted entry looks valid, zero
65 * if not valid.
66 */
ext2fs_validate_entry(ext2_filsys fs,char * buf,unsigned int offset,unsigned int final_offset)67 static int ext2fs_validate_entry(ext2_filsys fs, char *buf,
68 unsigned int offset,
69 unsigned int final_offset)
70 {
71 struct ext2_dir_entry *dirent;
72 unsigned int rec_len;
73 #define DIRENT_MIN_LENGTH 12
74
75 while ((offset < final_offset) &&
76 (offset <= fs->blocksize - DIRENT_MIN_LENGTH)) {
77 dirent = (struct ext2_dir_entry *)(buf + offset);
78 if (ext2fs_get_rec_len(fs, dirent, &rec_len))
79 return 0;
80 offset += rec_len;
81 if ((rec_len < 8) ||
82 ((rec_len % 4) != 0) ||
83 ((((unsigned) dirent->name_len & 0xFF)+8) > rec_len))
84 return 0;
85 }
86 return (offset == final_offset);
87 }
88
ext2fs_dir_iterate2(ext2_filsys fs,ext2_ino_t dir,int flags,char * block_buf,int (* func)(ext2_ino_t dir,int entry,struct ext2_dir_entry * dirent,int offset,int blocksize,char * buf,void * priv_data),void * priv_data)89 errcode_t ext2fs_dir_iterate2(ext2_filsys fs,
90 ext2_ino_t dir,
91 int flags,
92 char *block_buf,
93 int (*func)(ext2_ino_t dir,
94 int entry,
95 struct ext2_dir_entry *dirent,
96 int offset,
97 int blocksize,
98 char *buf,
99 void *priv_data),
100 void *priv_data)
101 {
102 struct dir_context ctx;
103 errcode_t retval;
104
105 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
106
107 retval = ext2fs_check_directory(fs, dir);
108 if (retval)
109 return retval;
110
111 ctx.dir = dir;
112 ctx.flags = flags;
113 if (block_buf)
114 ctx.buf = block_buf;
115 else {
116 retval = ext2fs_get_mem(fs->blocksize, &ctx.buf);
117 if (retval)
118 return retval;
119 }
120 ctx.func = func;
121 ctx.priv_data = priv_data;
122 ctx.errcode = 0;
123 retval = ext2fs_block_iterate2(fs, dir, BLOCK_FLAG_READ_ONLY, 0,
124 ext2fs_process_dir_block, &ctx);
125 if (!block_buf)
126 ext2fs_free_mem(&ctx.buf);
127 if (retval)
128 return retval;
129 return ctx.errcode;
130 }
131
132 struct xlate {
133 int (*func)(struct ext2_dir_entry *dirent,
134 int offset,
135 int blocksize,
136 char *buf,
137 void *priv_data);
138 void *real_private;
139 };
140
xlate_func(ext2_ino_t dir EXT2FS_ATTR ((unused)),int entry EXT2FS_ATTR ((unused)),struct ext2_dir_entry * dirent,int offset,int blocksize,char * buf,void * priv_data)141 static int xlate_func(ext2_ino_t dir EXT2FS_ATTR((unused)),
142 int entry EXT2FS_ATTR((unused)),
143 struct ext2_dir_entry *dirent, int offset,
144 int blocksize, char *buf, void *priv_data)
145 {
146 struct xlate *xl = (struct xlate *) priv_data;
147
148 return (*xl->func)(dirent, offset, blocksize, buf, xl->real_private);
149 }
150
ext2fs_dir_iterate(ext2_filsys fs,ext2_ino_t dir,int flags,char * block_buf,int (* func)(struct ext2_dir_entry * dirent,int offset,int blocksize,char * buf,void * priv_data),void * priv_data)151 extern errcode_t ext2fs_dir_iterate(ext2_filsys fs,
152 ext2_ino_t dir,
153 int flags,
154 char *block_buf,
155 int (*func)(struct ext2_dir_entry *dirent,
156 int offset,
157 int blocksize,
158 char *buf,
159 void *priv_data),
160 void *priv_data)
161 {
162 struct xlate xl;
163
164 xl.real_private = priv_data;
165 xl.func = func;
166
167 return ext2fs_dir_iterate2(fs, dir, flags, block_buf,
168 xlate_func, &xl);
169 }
170
171
172 /*
173 * Helper function which is private to this module. Used by
174 * ext2fs_dir_iterate() and ext2fs_dblist_dir_iterate()
175 */
ext2fs_process_dir_block(ext2_filsys fs,blk_t * blocknr,e2_blkcnt_t blockcnt,blk_t ref_block EXT2FS_ATTR ((unused)),int ref_offset EXT2FS_ATTR ((unused)),void * priv_data)176 int ext2fs_process_dir_block(ext2_filsys fs,
177 blk_t *blocknr,
178 e2_blkcnt_t blockcnt,
179 blk_t ref_block EXT2FS_ATTR((unused)),
180 int ref_offset EXT2FS_ATTR((unused)),
181 void *priv_data)
182 {
183 struct dir_context *ctx = (struct dir_context *) priv_data;
184 unsigned int offset = 0;
185 unsigned int next_real_entry = 0;
186 int ret = 0;
187 int changed = 0;
188 int do_abort = 0;
189 unsigned int rec_len, size;
190 int entry;
191 struct ext2_dir_entry *dirent;
192
193 if (blockcnt < 0)
194 return 0;
195
196 entry = blockcnt ? DIRENT_OTHER_FILE : DIRENT_DOT_FILE;
197
198 ctx->errcode = ext2fs_read_dir_block(fs, *blocknr, ctx->buf);
199 if (ctx->errcode)
200 return BLOCK_ABORT;
201
202 while (offset < fs->blocksize) {
203 dirent = (struct ext2_dir_entry *) (ctx->buf + offset);
204 if (ext2fs_get_rec_len(fs, dirent, &rec_len))
205 return BLOCK_ABORT;
206 if (((offset + rec_len) > fs->blocksize) ||
207 (rec_len < 8) ||
208 ((rec_len % 4) != 0) ||
209 ((((unsigned) dirent->name_len & 0xFF)+8) > rec_len)) {
210 ctx->errcode = EXT2_ET_DIR_CORRUPTED;
211 return BLOCK_ABORT;
212 }
213 if (!dirent->inode &&
214 !(ctx->flags & DIRENT_FLAG_INCLUDE_EMPTY))
215 goto next;
216
217 ret = (ctx->func)(ctx->dir,
218 (next_real_entry > offset) ?
219 DIRENT_DELETED_FILE : entry,
220 dirent, offset,
221 fs->blocksize, ctx->buf,
222 ctx->priv_data);
223 if (entry < DIRENT_OTHER_FILE)
224 entry++;
225
226 if (ret & DIRENT_CHANGED) {
227 if (ext2fs_get_rec_len(fs, dirent, &rec_len))
228 return BLOCK_ABORT;
229 changed++;
230 }
231 if (ret & DIRENT_ABORT) {
232 do_abort++;
233 break;
234 }
235 next:
236 if (next_real_entry == offset)
237 next_real_entry += rec_len;
238
239 if (ctx->flags & DIRENT_FLAG_INCLUDE_REMOVED) {
240 size = ((dirent->name_len & 0xFF) + 11) & ~3;
241
242 if (rec_len != size) {
243 unsigned int final_offset;
244
245 final_offset = offset + rec_len;
246 offset += size;
247 while (offset < final_offset &&
248 !ext2fs_validate_entry(fs, ctx->buf,
249 offset,
250 final_offset))
251 offset += 4;
252 continue;
253 }
254 }
255 offset += rec_len;
256 }
257
258 if (changed) {
259 ctx->errcode = ext2fs_write_dir_block(fs, *blocknr, ctx->buf);
260 if (ctx->errcode)
261 return BLOCK_ABORT;
262 }
263 if (do_abort)
264 return BLOCK_ABORT;
265 return 0;
266 }
267
268