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(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	}
121out_iter:
122	udf_fiiter_release(&iter);
123out:
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 */
132const 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