1/*
2 *  linux/fs/isofs/namei.c
3 *
4 *  (C) 1992  Eric Youngdale Modified for ISO 9660 filesystem.
5 *
6 *  (C) 1991  Linus Torvalds - minix filesystem
7 */
8
9#include <linux/smp_lock.h>
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
23	if (!compare)
24		return 1;
25
26	/* check special "." and ".." files */
27	if (dlen == 1) {
28		/* "." */
29		if (compare[0] == 0) {
30			if (!dentry->d_name.len)
31				return 0;
32			compare = ".";
33		} else if (compare[0] == 1) {
34			compare = "..";
35			dlen = 2;
36		}
37	}
38
39	qstr.name = compare;
40	qstr.len = dlen;
41	return dentry->d_op->d_compare(dentry, &dentry->d_name, &qstr);
42}
43
44/*
45 *	isofs_find_entry()
46 *
47 * finds an entry in the specified directory with the wanted name. It
48 * returns the inode number of the found entry, or 0 on error.
49 */
50static unsigned long
51isofs_find_entry(struct inode *dir, struct dentry *dentry,
52	unsigned long *block_rv, unsigned long *offset_rv,
53	char *tmpname, struct iso_directory_record *tmpde)
54{
55	unsigned long bufsize = ISOFS_BUFFER_SIZE(dir);
56	unsigned char bufbits = ISOFS_BUFFER_BITS(dir);
57	unsigned long block, f_pos, offset, block_saved, offset_saved;
58	struct buffer_head *bh = NULL;
59	struct isofs_sb_info *sbi = ISOFS_SB(dir->i_sb);
60
61	if (!ISOFS_I(dir)->i_first_extent)
62		return 0;
63
64	f_pos = 0;
65	offset = 0;
66	block = 0;
67
68	while (f_pos < dir->i_size) {
69		struct iso_directory_record *de;
70		int de_len, match, i, dlen;
71		char *dpnt;
72
73		if (!bh) {
74			bh = isofs_bread(dir, block);
75			if (!bh)
76				return 0;
77		}
78
79		de = (struct iso_directory_record *) (bh->b_data + offset);
80
81		de_len = *(unsigned char *) de;
82		if (!de_len) {
83			brelse(bh);
84			bh = NULL;
85			f_pos = (f_pos + ISOFS_BLOCK_SIZE) & ~(ISOFS_BLOCK_SIZE - 1);
86			block = f_pos >> bufbits;
87			offset = 0;
88			continue;
89		}
90
91		block_saved = bh->b_blocknr;
92		offset_saved = offset;
93		offset += de_len;
94		f_pos += de_len;
95
96		/* Make sure we have a full directory entry */
97		if (offset >= bufsize) {
98			int slop = bufsize - offset + de_len;
99			memcpy(tmpde, de, slop);
100			offset &= bufsize - 1;
101			block++;
102			brelse(bh);
103			bh = NULL;
104			if (offset) {
105				bh = isofs_bread(dir, block);
106				if (!bh)
107					return 0;
108				memcpy((void *) tmpde + slop, bh->b_data, offset);
109			}
110			de = tmpde;
111		}
112
113		dlen = de->name_len[0];
114		dpnt = de->name;
115		/* Basic sanity check, whether name doesn't exceed dir entry */
116		if (de_len < dlen + sizeof(struct iso_directory_record)) {
117			printk(KERN_NOTICE "iso9660: Corrupted directory entry"
118			       " in block %lu of inode %lu\n", block,
119			       dir->i_ino);
120			return 0;
121		}
122
123		if (sbi->s_rock &&
124		    ((i = get_rock_ridge_filename(de, tmpname, dir)))) {
125			dlen = i;	/* possibly -1 */
126			dpnt = tmpname;
127#ifdef CONFIG_JOLIET
128		} else if (sbi->s_joliet_level) {
129			dlen = get_joliet_filename(de, tmpname, dir);
130			dpnt = tmpname;
131#endif
132		} else if (sbi->s_mapping == 'a') {
133			dlen = get_acorn_filename(de, tmpname, dir);
134			dpnt = tmpname;
135		} else if (sbi->s_mapping == 'n') {
136			dlen = isofs_name_translate(de, tmpname, dir);
137			dpnt = tmpname;
138		}
139
140		/*
141		 * Skip hidden or associated files unless hide or showassoc,
142		 * respectively, is set
143		 */
144		match = 0;
145		if (dlen > 0 &&
146			(!sbi->s_hide ||
147				(!(de->flags[-sbi->s_high_sierra] & 1))) &&
148			(sbi->s_showassoc ||
149				(!(de->flags[-sbi->s_high_sierra] & 4)))) {
150			match = (isofs_cmp(dentry, dpnt, dlen) == 0);
151		}
152		if (match) {
153			isofs_normalize_block_and_offset(de,
154							 &block_saved,
155							 &offset_saved);
156			*block_rv = block_saved;
157			*offset_rv = offset_saved;
158			brelse(bh);
159			return 1;
160		}
161	}
162	brelse(bh);
163	return 0;
164}
165
166struct dentry *isofs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
167{
168	int found;
169	unsigned long uninitialized_var(block);
170	unsigned long uninitialized_var(offset);
171	struct inode *inode;
172	struct page *page;
173
174	dentry->d_op = dir->i_sb->s_root->d_op;
175
176	page = alloc_page(GFP_USER);
177	if (!page)
178		return ERR_PTR(-ENOMEM);
179
180	lock_kernel();
181	found = isofs_find_entry(dir, dentry,
182				&block, &offset,
183				page_address(page),
184				1024 + page_address(page));
185	__free_page(page);
186
187	inode = NULL;
188	if (found) {
189		inode = isofs_iget(dir->i_sb, block, offset);
190		if (IS_ERR(inode)) {
191			unlock_kernel();
192			return ERR_CAST(inode);
193		}
194	}
195	unlock_kernel();
196	return d_splice_alias(inode, dentry);
197}
198