1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * dir.c
4 *
5 * PURPOSE
6 * Directory handling routines for the OSTA-UDF(tm) filesystem.
7 *
8 * COPYRIGHT
9 * (C) 1998-2004 Ben Fennema
10 *
11 * HISTORY
12 *
13 * 10/05/98 dgb Split directory operations into its own file
14 * Implemented directory reads via do_udf_readdir
15 * 10/06/98 Made directory operations work!
16 * 11/17/98 Rewrote directory to support ICBTAG_FLAG_AD_LONG
17 * 11/25/98 blf Rewrote directory handling (readdir+lookup) to support reading
18 * across blocks.
19 * 12/12/98 Split out the lookup code to namei.c. bulk of directory
20 * code now in directory.c:udf_fileident_read.
21 */
22
23 #include "udfdecl.h"
24
25 #include <linux/string.h>
26 #include <linux/errno.h>
27 #include <linux/mm.h>
28 #include <linux/slab.h>
29 #include <linux/bio.h>
30 #include <linux/iversion.h>
31
32 #include "udf_i.h"
33 #include "udf_sb.h"
34
35 static int udf_readdir(struct file *file, struct dir_context *ctx)
36 {
37 struct inode *dir = file_inode(file);
38 loff_t nf_pos, emit_pos = 0;
39 int flen;
40 unsigned char *fname = NULL;
41 int ret = 0;
42 struct super_block *sb = dir->i_sb;
43 bool pos_valid = false;
44 struct udf_fileident_iter iter;
45
46 if (ctx->pos == 0) {
47 if (!dir_emit_dot(file, ctx))
48 return 0;
49 ctx->pos = 1;
50 }
51 nf_pos = (ctx->pos - 1) << 2;
52 if (nf_pos >= dir->i_size)
53 goto out;
54
55 /*
56 * Something changed since last readdir (either lseek was called or dir
57 * changed)? We need to verify the position correctly points at the
58 * beginning of some dir entry so that the directory parsing code does
59 * not get confused. Since UDF does not have any reliable way of
60 * identifying beginning of dir entry (names are under user control),
61 * we need to scan the directory from the beginning.
62 */
63 if (!inode_eq_iversion(dir, file->f_version)) {
64 emit_pos = nf_pos;
65 nf_pos = 0;
66 } else {
67 pos_valid = true;
68 }
69
70 fname = kmalloc(UDF_NAME_LEN, GFP_KERNEL);
71 if (!fname) {
72 ret = -ENOMEM;
73 goto out;
74 }
75
76 for (ret = udf_fiiter_init(&iter, dir, nf_pos);
77 !ret && iter.pos < dir->i_size;
78 ret = udf_fiiter_advance(&iter)) {
79 struct kernel_lb_addr tloc;
80 udf_pblk_t iblock;
81
82 /* Still not at offset where user asked us to read from? */
83 if (iter.pos < emit_pos)
84 continue;
85
86 /* Update file position only if we got past the current one */
87 pos_valid = true;
88 ctx->pos = (iter.pos >> 2) + 1;
89
90 if (iter.fi.fileCharacteristics & FID_FILE_CHAR_DELETED) {
91 if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNDELETE))
92 continue;
93 }
94
95 if (iter.fi.fileCharacteristics & FID_FILE_CHAR_HIDDEN) {
96 if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNHIDE))
97 continue;
98 }
99
100 if (iter.fi.fileCharacteristics & FID_FILE_CHAR_PARENT) {
101 if (!dir_emit_dotdot(file, ctx))
102 goto out_iter;
103 continue;
104 }
105
106 flen = udf_get_filename(sb, iter.name,
107 iter.fi.lengthFileIdent, fname, UDF_NAME_LEN);
108 if (flen < 0)
109 continue;
110
111 tloc = lelb_to_cpu(iter.fi.icb.extLocation);
112 iblock = udf_get_lb_pblock(sb, &tloc, 0);
113 if (!dir_emit(ctx, fname, flen, iblock, DT_UNKNOWN))
114 goto out_iter;
115 }
116
117 if (!ret) {
118 ctx->pos = (iter.pos >> 2) + 1;
119 pos_valid = true;
120 }
121 out_iter:
122 udf_fiiter_release(&iter);
123 out:
124 if (pos_valid)
125 file->f_version = inode_query_iversion(dir);
126 kfree(fname);
127
128 return ret;
129 }
130
131 /* readdir and lookup functions */
132 const struct file_operations udf_dir_operations = {
133 .llseek = generic_file_llseek,
134 .read = generic_read_dir,
135 .iterate_shared = udf_readdir,
136 .unlocked_ioctl = udf_ioctl,
137 .fsync = generic_file_fsync,
138 };
139
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