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 Library
8 * General Public License, version 2.
9 * %End-Header%
10 */
11
12 #include "config.h"
13 #include <stdio.h>
14 #include <string.h>
15 #if HAVE_UNISTD_H
16 #include <unistd.h>
17 #endif
18 #if HAVE_ERRNO_H
19 #include <errno.h>
20 #endif
21
22 #include "ext2_fs.h"
23 #include "ext2fsP.h"
24
25 #define EXT4_MAX_REC_LEN ((1<<16)-1)
26
ext2fs_get_rec_len(ext2_filsys fs,struct ext2_dir_entry * dirent,unsigned int * rec_len)27 errcode_t ext2fs_get_rec_len(ext2_filsys fs,
28 struct ext2_dir_entry *dirent,
29 unsigned int *rec_len)
30 {
31 unsigned int len = dirent->rec_len;
32
33 if (fs->blocksize < 65536)
34 *rec_len = len;
35 else if (len == EXT4_MAX_REC_LEN || len == 0)
36 *rec_len = fs->blocksize;
37 else
38 *rec_len = (len & 65532) | ((len & 3) << 16);
39 return 0;
40 }
41
ext2fs_set_rec_len(ext2_filsys fs,unsigned int len,struct ext2_dir_entry * dirent)42 errcode_t ext2fs_set_rec_len(ext2_filsys fs,
43 unsigned int len,
44 struct ext2_dir_entry *dirent)
45 {
46 if ((len > fs->blocksize) || (fs->blocksize > (1 << 18)) || (len & 3))
47 return EINVAL;
48 if (len < 65536) {
49 dirent->rec_len = len;
50 return 0;
51 }
52 if (len == fs->blocksize) {
53 if (fs->blocksize == 65536)
54 dirent->rec_len = EXT4_MAX_REC_LEN;
55 else
56 dirent->rec_len = 0;
57 } else
58 dirent->rec_len = (len & 65532) | ((len >> 16) & 3);
59 return 0;
60 }
61
62 /*
63 * This function checks to see whether or not a potential deleted
64 * directory entry looks valid. What we do is check the deleted entry
65 * and each successive entry to make sure that they all look valid and
66 * that the last deleted entry ends at the beginning of the next
67 * undeleted entry. Returns 1 if the deleted entry looks valid, zero
68 * if not valid.
69 */
ext2fs_validate_entry(ext2_filsys fs,char * buf,unsigned int offset,unsigned int final_offset)70 static int ext2fs_validate_entry(ext2_filsys fs, char *buf,
71 unsigned int offset,
72 unsigned int final_offset)
73 {
74 struct ext2_dir_entry *dirent;
75 unsigned int rec_len;
76 #define DIRENT_MIN_LENGTH 12
77
78 while ((offset < final_offset) &&
79 (offset <= fs->blocksize - DIRENT_MIN_LENGTH)) {
80 dirent = (struct ext2_dir_entry *)(buf + offset);
81 if (ext2fs_get_rec_len(fs, dirent, &rec_len))
82 return 0;
83 offset += rec_len;
84 if ((rec_len < 8) ||
85 ((rec_len % 4) != 0) ||
86 ((ext2fs_dirent_name_len(dirent)+8) > (int) rec_len))
87 return 0;
88 }
89 return (offset == final_offset);
90 }
91
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)92 errcode_t ext2fs_dir_iterate2(ext2_filsys fs,
93 ext2_ino_t dir,
94 int flags,
95 char *block_buf,
96 int (*func)(ext2_ino_t dir,
97 int entry,
98 struct ext2_dir_entry *dirent,
99 int offset,
100 int blocksize,
101 char *buf,
102 void *priv_data),
103 void *priv_data)
104 {
105 struct dir_context ctx;
106 errcode_t retval;
107
108 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
109
110 retval = ext2fs_check_directory(fs, dir);
111 if (retval)
112 return retval;
113
114 ctx.dir = dir;
115 ctx.flags = flags;
116 if (block_buf)
117 ctx.buf = block_buf;
118 else {
119 retval = ext2fs_get_mem(fs->blocksize, &ctx.buf);
120 if (retval)
121 return retval;
122 }
123 ctx.func = func;
124 ctx.priv_data = priv_data;
125 ctx.errcode = 0;
126 retval = ext2fs_block_iterate3(fs, dir, BLOCK_FLAG_READ_ONLY, 0,
127 ext2fs_process_dir_block, &ctx);
128 if (!block_buf)
129 ext2fs_free_mem(&ctx.buf);
130 if (retval == EXT2_ET_INLINE_DATA_CANT_ITERATE) {
131 (void) ext2fs_inline_data_dir_iterate(fs, dir, &ctx);
132 retval = 0;
133 }
134 if (retval)
135 return retval;
136 return ctx.errcode;
137 }
138
139 struct xlate {
140 int (*func)(struct ext2_dir_entry *dirent,
141 int offset,
142 int blocksize,
143 char *buf,
144 void *priv_data);
145 void *real_private;
146 };
147
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)148 static int xlate_func(ext2_ino_t dir EXT2FS_ATTR((unused)),
149 int entry EXT2FS_ATTR((unused)),
150 struct ext2_dir_entry *dirent, int offset,
151 int blocksize, char *buf, void *priv_data)
152 {
153 struct xlate *xl = (struct xlate *) priv_data;
154
155 return (*xl->func)(dirent, offset, blocksize, buf, xl->real_private);
156 }
157
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)158 errcode_t ext2fs_dir_iterate(ext2_filsys fs,
159 ext2_ino_t dir,
160 int flags,
161 char *block_buf,
162 int (*func)(struct ext2_dir_entry *dirent,
163 int offset,
164 int blocksize,
165 char *buf,
166 void *priv_data),
167 void *priv_data)
168 {
169 struct xlate xl;
170
171 xl.real_private = priv_data;
172 xl.func = func;
173
174 return ext2fs_dir_iterate2(fs, dir, flags, block_buf,
175 xlate_func, &xl);
176 }
177
178
179 /*
180 * Helper function which is private to this module. Used by
181 * ext2fs_dir_iterate() and ext2fs_dblist_dir_iterate()
182 */
ext2fs_process_dir_block(ext2_filsys fs,blk64_t * blocknr,e2_blkcnt_t blockcnt,blk64_t ref_block EXT2FS_ATTR ((unused)),int ref_offset EXT2FS_ATTR ((unused)),void * priv_data)183 int ext2fs_process_dir_block(ext2_filsys fs,
184 blk64_t *blocknr,
185 e2_blkcnt_t blockcnt,
186 blk64_t ref_block EXT2FS_ATTR((unused)),
187 int ref_offset EXT2FS_ATTR((unused)),
188 void *priv_data)
189 {
190 struct dir_context *ctx = (struct dir_context *) priv_data;
191 unsigned int offset = 0;
192 unsigned int next_real_entry = 0;
193 int ret = 0;
194 int changed = 0;
195 int do_abort = 0;
196 unsigned int rec_len, size, buflen;
197 int entry;
198 struct ext2_dir_entry *dirent;
199 int csum_size = 0;
200 int inline_data;
201 errcode_t retval = 0;
202
203 if (blockcnt < 0)
204 return 0;
205
206 entry = blockcnt ? DIRENT_OTHER_FILE : DIRENT_DOT_FILE;
207
208 /* If a dir has inline data, we don't need to read block */
209 inline_data = !!(ctx->flags & DIRENT_FLAG_INCLUDE_INLINE_DATA);
210 if (!inline_data) {
211 ctx->errcode = ext2fs_read_dir_block4(fs, *blocknr, ctx->buf, 0,
212 ctx->dir);
213 if (ctx->errcode)
214 return BLOCK_ABORT;
215 /* If we handle a normal dir, we traverse the entire block */
216 buflen = fs->blocksize;
217 } else {
218 buflen = ctx->buflen;
219 }
220
221 if (ext2fs_has_feature_metadata_csum(fs->super))
222 csum_size = sizeof(struct ext2_dir_entry_tail);
223
224 while (offset < buflen - 8) {
225 dirent = (struct ext2_dir_entry *) (ctx->buf + offset);
226 if (ext2fs_get_rec_len(fs, dirent, &rec_len))
227 return BLOCK_ABORT;
228 if (((offset + rec_len) > buflen) ||
229 (rec_len < 8) ||
230 ((rec_len % 4) != 0) ||
231 ((ext2fs_dirent_name_len(dirent)+8) > (int) rec_len)) {
232 ctx->errcode = EXT2_ET_DIR_CORRUPTED;
233 return BLOCK_ABORT;
234 }
235 if (!dirent->inode) {
236 /*
237 * We just need to check metadata_csum when this
238 * dir hasn't inline data. That means that 'buflen'
239 * should be blocksize.
240 */
241 if (!inline_data &&
242 (offset == buflen - csum_size) &&
243 (dirent->rec_len == csum_size) &&
244 (dirent->name_len == EXT2_DIR_NAME_LEN_CSUM)) {
245 if (!(ctx->flags & DIRENT_FLAG_INCLUDE_CSUM))
246 goto next;
247 entry = DIRENT_CHECKSUM;
248 } else if (!(ctx->flags & DIRENT_FLAG_INCLUDE_EMPTY))
249 goto next;
250 }
251
252 ret = (ctx->func)(ctx->dir,
253 (next_real_entry > offset) ?
254 DIRENT_DELETED_FILE : entry,
255 dirent, offset,
256 buflen, ctx->buf,
257 ctx->priv_data);
258 if (entry < DIRENT_OTHER_FILE)
259 entry++;
260
261 if (ret & DIRENT_CHANGED) {
262 if (ext2fs_get_rec_len(fs, dirent, &rec_len))
263 return BLOCK_ABORT;
264 changed++;
265 }
266 if (ret & DIRENT_ABORT) {
267 do_abort++;
268 break;
269 }
270 next:
271 if (next_real_entry == offset)
272 next_real_entry += rec_len;
273
274 if (ctx->flags & DIRENT_FLAG_INCLUDE_REMOVED) {
275 size = (ext2fs_dirent_name_len(dirent) + 11) & ~3;
276
277 if (rec_len != size) {
278 unsigned int final_offset;
279
280 final_offset = offset + rec_len;
281 offset += size;
282 while (offset < final_offset &&
283 !ext2fs_validate_entry(fs, ctx->buf,
284 offset,
285 final_offset))
286 offset += 4;
287 continue;
288 }
289 }
290 offset += rec_len;
291 }
292
293 if (changed) {
294 if (!inline_data) {
295 ctx->errcode = ext2fs_write_dir_block4(fs, *blocknr,
296 ctx->buf,
297 0, ctx->dir);
298 if (ctx->errcode)
299 return BLOCK_ABORT;
300 } else {
301 /*
302 * return BLOCK_INLINE_DATA_CHANGED to notify caller
303 * that inline data has been changed.
304 */
305 retval = BLOCK_INLINE_DATA_CHANGED;
306 }
307 }
308 if (do_abort)
309 return retval | BLOCK_ABORT;
310 return retval;
311 }
312