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 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, 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 */ 34 static unsigned long 35 isofs_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 } 150 151 struct 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