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