1// SPDX-License-Identifier: GPL-2.0
2/*
3 *  linux/fs/isofs/namei.c
4 *
5 *  (C) 1992  Eric Youngdale Modified for ISO 9660 filesystem.
6 *
7 *  (C) 1991  Linus Torvalds - minix filesystem
8 */
9
10#include <linux/gfp.h>
11#include "isofs.h"
12
13/*
14 * ok, we cannot use strncmp, as the name is not in our data space.
15 * Thus we'll have to use isofs_match. No big problem. Match also makes
16 * some sanity tests.
17 */
18static int
19isofs_cmp(struct dentry *dentry, const char *compare, int dlen)
20{
21	struct qstr qstr;
22	qstr.name = compare;
23	qstr.len = dlen;
24	if (likely(!dentry->d_op))
25		return dentry->d_name.len != dlen || memcmp(dentry->d_name.name, compare, dlen);
26	return dentry->d_op->d_compare(NULL, dentry->d_name.len, dentry->d_name.name, &qstr);
27}
28
29/*
30 *	isofs_find_entry()
31 *
32 * finds an entry in the specified directory with the wanted name. It
33 * returns the inode number of the found entry, or 0 on error.
34 */
35static unsigned long
36isofs_find_entry(struct inode *dir, struct dentry *dentry,
37	unsigned long *block_rv, unsigned long *offset_rv,
38	char *tmpname, struct iso_directory_record *tmpde)
39{
40	unsigned long bufsize = ISOFS_BUFFER_SIZE(dir);
41	unsigned char bufbits = ISOFS_BUFFER_BITS(dir);
42	unsigned long block, f_pos, offset, block_saved, offset_saved;
43	struct buffer_head *bh = NULL;
44	struct isofs_sb_info *sbi = ISOFS_SB(dir->i_sb);
45
46	if (!ISOFS_I(dir)->i_first_extent)
47		return 0;
48
49	f_pos = 0;
50	offset = 0;
51	block = 0;
52
53	while (f_pos < dir->i_size) {
54		struct iso_directory_record *de;
55		int de_len, match, i, dlen;
56		char *dpnt;
57
58		if (!bh) {
59			bh = isofs_bread(dir, block);
60			if (!bh)
61				return 0;
62		}
63
64		de = (struct iso_directory_record *) (bh->b_data + offset);
65
66		de_len = *(unsigned char *) de;
67		if (!de_len) {
68			brelse(bh);
69			bh = NULL;
70			f_pos = (f_pos + ISOFS_BLOCK_SIZE) & ~(ISOFS_BLOCK_SIZE - 1);
71			block = f_pos >> bufbits;
72			offset = 0;
73			continue;
74		}
75
76		block_saved = bh->b_blocknr;
77		offset_saved = offset;
78		offset += de_len;
79		f_pos += de_len;
80
81		/* Make sure we have a full directory entry */
82		if (offset >= bufsize) {
83			int slop = bufsize - offset + de_len;
84			memcpy(tmpde, de, slop);
85			offset &= bufsize - 1;
86			block++;
87			brelse(bh);
88			bh = NULL;
89			if (offset) {
90				bh = isofs_bread(dir, block);
91				if (!bh)
92					return 0;
93				memcpy((void *) tmpde + slop, bh->b_data, offset);
94			}
95			de = tmpde;
96		}
97
98		dlen = de->name_len[0];
99		dpnt = de->name;
100		/* Basic sanity check, whether name doesn't exceed dir entry */
101		if (de_len < dlen + sizeof(struct iso_directory_record)) {
102			printk(KERN_NOTICE "iso9660: Corrupted directory entry"
103			       " in block %lu of inode %lu\n", block,
104			       dir->i_ino);
105			brelse(bh);
106			return 0;
107		}
108
109		if (sbi->s_rock &&
110		    ((i = get_rock_ridge_filename(de, tmpname, dir)))) {
111			dlen = i;	/* possibly -1 */
112			dpnt = tmpname;
113#ifdef CONFIG_JOLIET
114		} else if (sbi->s_joliet_level) {
115			dlen = get_joliet_filename(de, tmpname, dir);
116			dpnt = tmpname;
117#endif
118		} else if (sbi->s_mapping == 'a') {
119			dlen = get_acorn_filename(de, tmpname, dir);
120			dpnt = tmpname;
121		} else if (sbi->s_mapping == 'n') {
122			dlen = isofs_name_translate(de, tmpname, dir);
123			dpnt = tmpname;
124		}
125
126		/*
127		 * Skip hidden or associated files unless hide or showassoc,
128		 * respectively, is set
129		 */
130		match = 0;
131		if (dlen > 0 &&
132			(!sbi->s_hide ||
133				(!(de->flags[-sbi->s_high_sierra] & 1))) &&
134			(sbi->s_showassoc ||
135				(!(de->flags[-sbi->s_high_sierra] & 4)))) {
136			if (dpnt && (dlen > 1 || dpnt[0] > 1))
137				match = (isofs_cmp(dentry, dpnt, dlen) == 0);
138		}
139		if (match) {
140			isofs_normalize_block_and_offset(de,
141							 &block_saved,
142							 &offset_saved);
143			*block_rv = block_saved;
144			*offset_rv = offset_saved;
145			brelse(bh);
146			return 1;
147		}
148	}
149	brelse(bh);
150	return 0;
151}
152
153struct dentry *isofs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
154{
155	int found;
156	unsigned long block;
157	unsigned long offset;
158	struct inode *inode;
159	struct page *page;
160
161	page = alloc_page(GFP_USER);
162	if (!page)
163		return ERR_PTR(-ENOMEM);
164
165	found = isofs_find_entry(dir, dentry,
166				&block, &offset,
167				page_address(page),
168				1024 + page_address(page));
169	__free_page(page);
170
171	inode = found ? isofs_iget(dir->i_sb, block, offset) : NULL;
172
173	return d_splice_alias(inode, dentry);
174}
175