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(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: 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: &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 | } |
121 | out_iter: |
122 | udf_fiiter_release(iter: &iter); |
123 | out: |
124 | if (pos_valid) |
125 | file->f_version = inode_query_iversion(inode: dir); |
126 | kfree(objp: 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 | |