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 */ 17 static int 18 isofs_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 */ 50 static unsigned long 51 isofs_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 } 165 166 struct 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 isofs_sb_info *sbi = ISOFS_SB(dir->i_sb); 172 struct inode *inode; 173 struct page *page; 174 175 d_set_d_op(dentry, dir->i_sb->s_root->d_op); 176 177 page = alloc_page(GFP_USER); 178 if (!page) 179 return ERR_PTR(-ENOMEM); 180 181 mutex_lock(&sbi->s_mutex); 182 found = isofs_find_entry(dir, dentry, 183 &block, &offset, 184 page_address(page), 185 1024 + page_address(page)); 186 __free_page(page); 187 188 inode = NULL; 189 if (found) { 190 inode = isofs_iget(dir->i_sb, block, offset); 191 if (IS_ERR(inode)) { 192 mutex_unlock(&sbi->s_mutex); 193 return ERR_CAST(inode); 194 } 195 } 196 mutex_unlock(&sbi->s_mutex); 197 return d_splice_alias(inode, dentry); 198 } 199