dir_iterate.c revision 8bd0c95908baa3af706b9e731daff9472bec74c9 
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/*
25 * This function checks to see whether or not a potential deleted
26 * directory entry looks valid.  What we do is check the deleted entry
27 * and each successive entry to make sure that they all look valid and
28 * that the last deleted entry ends at the beginning of the next
29 * undeleted entry.  Returns 1 if the deleted entry looks valid, zero
30 * if not valid.
31 */
32static int ext2fs_validate_entry(char *buf, int offset, int final_offset)
33{
34	struct ext2_dir_entry *dirent;
35
36	while (offset < final_offset) {
37		dirent = (struct ext2_dir_entry *)(buf + offset);
38		offset += dirent->rec_len;
39		if ((dirent->rec_len < 8) ||
40		    ((dirent->rec_len % 4) != 0) ||
41		    (((dirent->name_len & 0xFF)+8) > dirent->rec_len))
42			return 0;
43	}
44	return (offset == final_offset);
45}
46
47errcode_t ext2fs_dir_iterate2(ext2_filsys fs,
48			      ext2_ino_t dir,
49			      int flags,
50			      char *block_buf,
51			      int (*func)(ext2_ino_t	dir,
52					  int		entry,
53					  struct ext2_dir_entry *dirent,
54					  int	offset,
55					  int	blocksize,
56					  char	*buf,
57					  void	*priv_data),
58			      void *priv_data)
59{
60	struct		dir_context	ctx;
61	errcode_t	retval;
62
63	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
64
65	retval = ext2fs_check_directory(fs, dir);
66	if (retval)
67		return retval;
68
69	ctx.dir = dir;
70	ctx.flags = flags;
71	if (block_buf)
72		ctx.buf = block_buf;
73	else {
74		retval = ext2fs_get_mem(fs->blocksize, (void **) &ctx.buf);
75		if (retval)
76			return retval;
77	}
78	ctx.func = func;
79	ctx.priv_data = priv_data;
80	ctx.errcode = 0;
81	retval = ext2fs_block_iterate2(fs, dir, 0, 0,
82				       ext2fs_process_dir_block, &ctx);
83	if (!block_buf)
84		ext2fs_free_mem((void **) &ctx.buf);
85	if (retval)
86		return retval;
87	return ctx.errcode;
88}
89
90struct xlate {
91	int (*func)(struct ext2_dir_entry *dirent,
92		    int		offset,
93		    int		blocksize,
94		    char	*buf,
95		    void	*priv_data);
96	void *real_private;
97};
98
99static int xlate_func(ext2_ino_t dir, int entry,
100		      struct ext2_dir_entry *dirent, int offset,
101		      int blocksize, char *buf, void *priv_data)
102{
103	struct xlate *xl = (struct xlate *) priv_data;
104
105	return (*xl->func)(dirent, offset, blocksize, buf, xl->real_private);
106}
107
108extern errcode_t ext2fs_dir_iterate(ext2_filsys fs,
109			      ext2_ino_t dir,
110			      int flags,
111			      char *block_buf,
112			      int (*func)(struct ext2_dir_entry *dirent,
113					  int	offset,
114					  int	blocksize,
115					  char	*buf,
116					  void	*priv_data),
117			      void *priv_data)
118{
119	struct xlate xl;
120
121	xl.real_private = priv_data;
122	xl.func = func;
123
124	return ext2fs_dir_iterate2(fs, dir, flags, block_buf,
125				   xlate_func, &xl);
126}
127
128
129/*
130 * Helper function which is private to this module.  Used by
131 * ext2fs_dir_iterate() and ext2fs_dblist_dir_iterate()
132 */
133int ext2fs_process_dir_block(ext2_filsys  	fs,
134			     blk_t		*blocknr,
135			     e2_blkcnt_t		blockcnt,
136			     blk_t		ref_block,
137			     int			ref_offset,
138			     void		*priv_data)
139{
140	struct dir_context *ctx = (struct dir_context *) priv_data;
141	int		offset = 0;
142	int		next_real_entry = 0;
143	int		ret = 0;
144	int		changed = 0;
145	int		do_abort = 0;
146	int		entry, size;
147	struct ext2_dir_entry *dirent;
148
149	if (blockcnt < 0)
150		return 0;
151
152	entry = blockcnt ? DIRENT_OTHER_FILE : DIRENT_DOT_FILE;
153
154	ctx->errcode = ext2fs_read_dir_block(fs, *blocknr, ctx->buf);
155	if (ctx->errcode)
156		return BLOCK_ABORT;
157
158	while (offset < fs->blocksize) {
159		dirent = (struct ext2_dir_entry *) (ctx->buf + offset);
160		if (((offset + dirent->rec_len) > fs->blocksize) ||
161		    (dirent->rec_len < 8) ||
162		    ((dirent->rec_len % 4) != 0) ||
163		    (((dirent->name_len & 0xFF)+8) > dirent->rec_len)) {
164			ctx->errcode = EXT2_ET_DIR_CORRUPTED;
165			return BLOCK_ABORT;
166		}
167		if (!dirent->inode &&
168		    !(ctx->flags & DIRENT_FLAG_INCLUDE_EMPTY))
169			goto next;
170
171		ret = (ctx->func)(ctx->dir,
172				  (next_real_entry > offset) ?
173				  DIRENT_DELETED_FILE : entry,
174				  dirent, offset,
175				  fs->blocksize, ctx->buf,
176				  ctx->priv_data);
177		if (entry < DIRENT_OTHER_FILE)
178			entry++;
179
180		if (ret & DIRENT_CHANGED)
181			changed++;
182		if (ret & DIRENT_ABORT) {
183			do_abort++;
184			break;
185		}
186next:
187 		if (next_real_entry == offset)
188			next_real_entry += dirent->rec_len;
189
190 		if (ctx->flags & DIRENT_FLAG_INCLUDE_REMOVED) {
191			size = ((dirent->name_len & 0xFF) + 11) & ~3;
192
193			if (dirent->rec_len != size)  {
194				int final_offset = offset + dirent->rec_len;
195
196				offset += size;
197				while (offset < final_offset &&
198				       !ext2fs_validate_entry(ctx->buf,
199							      offset,
200							      final_offset))
201					offset += 4;
202				continue;
203			}
204		}
205		offset += dirent->rec_len;
206	}
207
208	if (changed) {
209		ctx->errcode = ext2fs_write_dir_block(fs, *blocknr, ctx->buf);
210		if (ctx->errcode)
211			return BLOCK_ABORT;
212	}
213	if (do_abort)
214		return BLOCK_ABORT;
215	return 0;
216}
217
218