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/filelock.h>
28 #include <linux/mm.h>
29 #include <linux/slab.h>
30 #include <linux/bio.h>
31 #include <linux/iversion.h>
32
33 #include "udf_i.h"
34 #include "udf_sb.h"
35
udf_readdir(struct file * file,struct dir_context * ctx)36 static int udf_readdir(struct file *file, struct dir_context *ctx)
37 {
38 struct inode *dir = file_inode(file);
39 loff_t nf_pos, emit_pos = 0;
40 int flen;
41 unsigned char *fname = NULL;
42 int ret = 0;
43 struct super_block *sb = dir->i_sb;
44 bool pos_valid = false;
45 struct udf_fileident_iter iter;
46
47 if (ctx->pos == 0) {
48 if (!dir_emit_dot(file, ctx))
49 return 0;
50 ctx->pos = 1;
51 }
52 nf_pos = (ctx->pos - 1) << 2;
53 if (nf_pos >= dir->i_size)
54 goto out;
55
56 /*
57 * Something changed since last readdir (either lseek was called or dir
58 * changed)? We need to verify the position correctly points at the
59 * beginning of some dir entry so that the directory parsing code does
60 * not get confused. Since UDF does not have any reliable way of
61 * identifying beginning of dir entry (names are under user control),
62 * we need to scan the directory from the beginning.
63 */
64 if (!inode_eq_iversion(dir, *(u64 *)file->private_data)) {
65 emit_pos = nf_pos;
66 nf_pos = 0;
67 } else {
68 pos_valid = true;
69 }
70
71 fname = kmalloc(UDF_NAME_LEN, GFP_KERNEL);
72 if (!fname) {
73 ret = -ENOMEM;
74 goto out;
75 }
76
77 for (ret = udf_fiiter_init(&iter, dir, nf_pos);
78 !ret && iter.pos < dir->i_size;
79 ret = udf_fiiter_advance(&iter)) {
80 struct kernel_lb_addr tloc;
81 udf_pblk_t iblock;
82
83 /* Still not at offset where user asked us to read from? */
84 if (iter.pos < emit_pos)
85 continue;
86
87 /* Update file position only if we got past the current one */
88 pos_valid = true;
89 ctx->pos = (iter.pos >> 2) + 1;
90
91 if (iter.fi.fileCharacteristics & FID_FILE_CHAR_DELETED) {
92 if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNDELETE))
93 continue;
94 }
95
96 if (iter.fi.fileCharacteristics & FID_FILE_CHAR_HIDDEN) {
97 if (!UDF_QUERY_FLAG(sb, UDF_FLAG_UNHIDE))
98 continue;
99 }
100
101 if (iter.fi.fileCharacteristics & FID_FILE_CHAR_PARENT) {
102 if (!dir_emit_dotdot(file, ctx))
103 goto out_iter;
104 continue;
105 }
106
107 flen = udf_get_filename(sb, iter.name,
108 iter.fi.lengthFileIdent, fname, UDF_NAME_LEN);
109 if (flen < 0)
110 continue;
111
112 tloc = lelb_to_cpu(iter.fi.icb.extLocation);
113 iblock = udf_get_lb_pblock(sb, &tloc, 0);
114 if (!dir_emit(ctx, fname, flen, iblock, DT_UNKNOWN))
115 goto out_iter;
116 }
117
118 if (!ret) {
119 ctx->pos = (iter.pos >> 2) + 1;
120 pos_valid = true;
121 }
122 out_iter:
123 udf_fiiter_release(&iter);
124 out:
125 if (pos_valid)
126 *(u64 *)file->private_data = inode_query_iversion(dir);
127 kfree(fname);
128
129 return ret;
130 }
131
udf_dir_open(struct inode * inode,struct file * file)132 static int udf_dir_open(struct inode *inode, struct file *file)
133 {
134 file->private_data = kzalloc(sizeof(u64), GFP_KERNEL);
135 if (!file->private_data)
136 return -ENOMEM;
137 return 0;
138 }
139
udf_dir_release(struct inode * inode,struct file * file)140 static int udf_dir_release(struct inode *inode, struct file *file)
141 {
142 kfree(file->private_data);
143 return 0;
144 }
145
udf_dir_llseek(struct file * file,loff_t offset,int whence)146 static loff_t udf_dir_llseek(struct file *file, loff_t offset, int whence)
147 {
148 return generic_llseek_cookie(file, offset, whence,
149 (u64 *)file->private_data);
150 }
151
152 /* readdir and lookup functions */
153 const struct file_operations udf_dir_operations = {
154 .open = udf_dir_open,
155 .release = udf_dir_release,
156 .llseek = udf_dir_llseek,
157 .read = generic_read_dir,
158 .iterate_shared = udf_readdir,
159 .unlocked_ioctl = udf_ioctl,
160 .fsync = generic_file_fsync,
161 .setlease = generic_setlease,
162 };
163