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/fs/isofs/namei.c

https://bitbucket.org/cyanogenmod/android_kernel_asus_tf300t
C | 187 lines | 139 code | 22 blank | 26 comment | 31 complexity | 19da925986532fb74a2ef7d08eb41410 MD5 | raw file
Possible License(s): LGPL-2.0, AGPL-1.0, GPL-2.0
  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
 22	if (!compare)
 23		return 1;
 24
 25	/* check special "." and ".." files */
 26	if (dlen == 1) {
 27		/* "." */
 28		if (compare[0] == 0) {
 29			if (!dentry->d_name.len)
 30				return 0;
 31			compare = ".";
 32		} else if (compare[0] == 1) {
 33			compare = "..";
 34			dlen = 2;
 35		}
 36	}
 37
 38	qstr.name = compare;
 39	qstr.len = dlen;
 40	return dentry->d_op->d_compare(NULL, NULL, NULL, NULL,
 41			dentry->d_name.len, dentry->d_name.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	page = alloc_page(GFP_USER);
175	if (!page)
176		return ERR_PTR(-ENOMEM);
177
178	found = isofs_find_entry(dir, dentry,
179				&block, &offset,
180				page_address(page),
181				1024 + page_address(page));
182	__free_page(page);
183
184	inode = found ? isofs_iget(dir->i_sb, block, offset) : NULL;
185
186	return d_splice_alias(inode, dentry);
187}