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