1 /*
2 * dir.c
3 *
4 * PURPOSE
5 * Directory handling routines for the OSTA-UDF(tm) filesystem.
6 *
7 * COPYRIGHT
8 * This file is distributed under the terms of the GNU General Public
9 * License (GPL). Copies of the GPL can be obtained from:
10 * ftp://prep.ai.mit.edu/pub/gnu/GPL
11 * Each contributing author retains all rights to their own work.
12 *
13 * (C) 1998-2004 Ben Fennema
14 *
15 * HISTORY
16 *
17 * 10/05/98 dgb Split directory operations into its own file
18 * Implemented directory reads via do_udf_readdir
19 * 10/06/98 Made directory operations work!
20 * 11/17/98 Rewrote directory to support ICBTAG_FLAG_AD_LONG
21 * 11/25/98 blf Rewrote directory handling (readdir+lookup) to support reading
22 * across blocks.
23 * 12/12/98 Split out the lookup code to namei.c. bulk of directory
24 * code now in directory.c:udf_fileident_read.
25 */
26
27 #include "udfdecl.h"
28
29 #include <linux/string.h>
30 #include <linux/errno.h>
31 #include <linux/mm.h>
32 #include <linux/slab.h>
33 #include <linux/bio.h>
34 #include <linux/iversion.h>
35
36 #include "udf_i.h"
37 #include "udf_sb.h"
38
udf_readdir(struct file * file,struct dir_context * ctx)39 static int udf_readdir(struct file *file, struct dir_context *ctx)
40 {
41 struct inode *dir = file_inode(file);
42 loff_t nf_pos, emit_pos = 0;
43 int flen;
44 unsigned char *fname = NULL;
45 int ret = 0;
46 struct super_block *sb = dir->i_sb;
47 bool pos_valid = false;
48 struct udf_fileident_iter iter;
49
50 if (ctx->pos == 0) {
51 if (!dir_emit_dot(file, ctx))
52 return 0;
53 ctx->pos = 1;
54 }
55 nf_pos = (ctx->pos - 1) << 2;
56 if (nf_pos >= dir->i_size)
57 goto out;
58
59 /*
60 * Something changed since last readdir (either lseek was called or dir
61 * changed)? We need to verify the position correctly points at the
62 * beginning of some dir entry so that the directory parsing code does
63 * not get confused. Since UDF does not have any reliable way of
64 * identifying beginning of dir entry (names are under user control),
65 * we need to scan the directory from the beginning.
66 */
67 if (!inode_eq_iversion(dir, file->f_version)) {
68 emit_pos = nf_pos;
69 nf_pos = 0;
70 } else {
71 pos_valid = true;
72 }
73
74 fname = kmalloc(UDF_NAME_LEN, GFP_NOFS);
75 if (!fname) {
76 ret = -ENOMEM;
77 goto out;
78 }
79
80 for (ret = udf_fiiter_init(&iter, dir, nf_pos);
81 !ret && iter.pos < dir->i_size;
82 ret = udf_fiiter_advance(&iter)) {
83 struct kernel_lb_addr tloc;
84 udf_pblk_t iblock;
85
86 /* Still not at offset where user asked us to read from? */
87 if (iter.pos < emit_pos)
88 continue;
89
90 /* Update file position only if we got past the current one */
91 pos_valid = true;
92 ctx->pos = (iter.pos >> 2) + 1;
93
94 if (iter.fi.fileCharacteristics & FID_FILE_CHAR_DELETED) {
95 if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNDELETE))
96 continue;
97 }
98
99 if (iter.fi.fileCharacteristics & FID_FILE_CHAR_HIDDEN) {
100 if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNHIDE))
101 continue;
102 }
103
104 if (iter.fi.fileCharacteristics & FID_FILE_CHAR_PARENT) {
105 if (!dir_emit_dotdot(file, ctx))
106 goto out_iter;
107 continue;
108 }
109
110 flen = udf_get_filename(sb, iter.name,
111 iter.fi.lengthFileIdent, fname, UDF_NAME_LEN);
112 if (flen < 0)
113 continue;
114
115 tloc = lelb_to_cpu(iter.fi.icb.extLocation);
116 iblock = udf_get_lb_pblock(sb, &tloc, 0);
117 if (!dir_emit(ctx, fname, flen, iblock, DT_UNKNOWN))
118 goto out_iter;
119 }
120
121 if (!ret) {
122 ctx->pos = (iter.pos >> 2) + 1;
123 pos_valid = true;
124 }
125 out_iter:
126 udf_fiiter_release(&iter);
127 out:
128 if (pos_valid)
129 file->f_version = inode_query_iversion(dir);
130 kfree(fname);
131
132 return ret;
133 }
134
135 /* readdir and lookup functions */
136 const struct file_operations udf_dir_operations = {
137 .llseek = generic_file_llseek,
138 .read = generic_read_dir,
139 .iterate_shared = udf_readdir,
140 .unlocked_ioctl = udf_ioctl,
141 .fsync = generic_file_fsync,
142 };
143