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
35static int udf_readdir(struct file *file, struct dir_context *ctx)
36{
37 struct inode *dir = file_inode(f: 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(inode: dir, old: *(u64 *)file->private_data)) {
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: &iter, dir, pos: nf_pos);
77 !ret && iter.pos < dir->i_size;
78 ret = udf_fiiter_advance(iter: &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(in: iter.fi.icb.extLocation);
112 iblock = udf_get_lb_pblock(sb, loc: &tloc, offset: 0);
113 if (!dir_emit(ctx, name: fname, namelen: flen, ino: iblock, DT_UNKNOWN))
114 goto out_iter;
115 }
116
117 if (!ret) {
118 ctx->pos = (iter.pos >> 2) + 1;
119 pos_valid = true;
120 }
121out_iter:
122 udf_fiiter_release(iter: &iter);
123out:
124 if (pos_valid)
125 *(u64 *)file->private_data = inode_query_iversion(inode: dir);
126 kfree(objp: fname);
127
128 return ret;
129}
130
131static int udf_dir_open(struct inode *inode, struct file *file)
132{
133 file->private_data = kzalloc(sizeof(u64), GFP_KERNEL);
134 if (!file->private_data)
135 return -ENOMEM;
136 return 0;
137}
138
139static int udf_dir_release(struct inode *inode, struct file *file)
140{
141 kfree(objp: file->private_data);
142 return 0;
143}
144
145static loff_t udf_dir_llseek(struct file *file, loff_t offset, int whence)
146{
147 return generic_llseek_cookie(file, offset, whence,
148 cookie: (u64 *)file->private_data);
149}
150
151/* readdir and lookup functions */
152const struct file_operations udf_dir_operations = {
153 .open = udf_dir_open,
154 .release = udf_dir_release,
155 .llseek = udf_dir_llseek,
156 .read = generic_read_dir,
157 .iterate_shared = udf_readdir,
158 .unlocked_ioctl = udf_ioctl,
159 .fsync = generic_file_fsync,
160};
161

source code of linux/fs/udf/dir.c