1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/fs/isofs/namei.c 4 * 5 * (C) 1992 Eric Youngdale Modified for ISO 9660 filesystem. 6 * 7 * (C) 1991 Linus Torvalds - minix filesystem 8 */ 9 10 #include <linux/gfp.h> 11 #include "isofs.h" 12 13 /* 14 * ok, we cannot use strncmp, as the name is not in our data space. 15 * Thus we'll have to use isofs_match. No big problem. Match also makes 16 * some sanity tests. 17 */ 18 static int 19 isofs_cmp(struct dentry *dentry, const char *compare, int dlen) 20 { 21 struct qstr qstr; 22 qstr.name = compare; 23 qstr.len = dlen; 24 if (likely(!dentry->d_op)) 25 return dentry->d_name.len != dlen || memcmp(dentry->d_name.name, compare, dlen); 26 return dentry->d_op->d_compare(NULL, dentry->d_name.len, dentry->d_name.name, &qstr); 27 } 28 29 /* 30 * isofs_find_entry() 31 * 32 * finds an entry in the specified directory with the wanted name. It 33 * returns the inode number of the found entry, or 0 on error. 34 */ 35 static unsigned long 36 isofs_find_entry(struct inode *dir, struct dentry *dentry, 37 unsigned long *block_rv, unsigned long *offset_rv, 38 char *tmpname, struct iso_directory_record *tmpde) 39 { 40 unsigned long bufsize = ISOFS_BUFFER_SIZE(dir); 41 unsigned char bufbits = ISOFS_BUFFER_BITS(dir); 42 unsigned long block, f_pos, offset, block_saved, offset_saved; 43 struct buffer_head *bh = NULL; 44 struct isofs_sb_info *sbi = ISOFS_SB(dir->i_sb); 45 46 if (!ISOFS_I(dir)->i_first_extent) 47 return 0; 48 49 f_pos = 0; 50 offset = 0; 51 block = 0; 52 53 while (f_pos < dir->i_size) { 54 struct iso_directory_record *de; 55 int de_len, match, i, dlen; 56 char *dpnt; 57 58 if (!bh) { 59 bh = isofs_bread(dir, block); 60 if (!bh) 61 return 0; 62 } 63 64 de = (struct iso_directory_record *) (bh->b_data + offset); 65 66 de_len = *(unsigned char *) de; 67 if (!de_len) { 68 brelse(bh); 69 bh = NULL; 70 f_pos = (f_pos + ISOFS_BLOCK_SIZE) & ~(ISOFS_BLOCK_SIZE - 1); 71 block = f_pos >> bufbits; 72 offset = 0; 73 continue; 74 } 75 76 block_saved = bh->b_blocknr; 77 offset_saved = offset; 78 offset += de_len; 79 f_pos += de_len; 80 81 /* Make sure we have a full directory entry */ 82 if (offset >= bufsize) { 83 int slop = bufsize - offset + de_len; 84 memcpy(tmpde, de, slop); 85 offset &= bufsize - 1; 86 block++; 87 brelse(bh); 88 bh = NULL; 89 if (offset) { 90 bh = isofs_bread(dir, block); 91 if (!bh) 92 return 0; 93 memcpy((void *) tmpde + slop, bh->b_data, offset); 94 } 95 de = tmpde; 96 } 97 98 dlen = de->name_len[0]; 99 dpnt = de->name; 100 /* Basic sanity check, whether name doesn't exceed dir entry */ 101 if (de_len < dlen + sizeof(struct iso_directory_record)) { 102 printk(KERN_NOTICE "iso9660: Corrupted directory entry" 103 " in block %lu of inode %lu\n", block, 104 dir->i_ino); 105 return 0; 106 } 107 108 if (sbi->s_rock && 109 ((i = get_rock_ridge_filename(de, tmpname, dir)))) { 110 dlen = i; /* possibly -1 */ 111 dpnt = tmpname; 112 #ifdef CONFIG_JOLIET 113 } else if (sbi->s_joliet_level) { 114 dlen = get_joliet_filename(de, tmpname, dir); 115 dpnt = tmpname; 116 #endif 117 } else if (sbi->s_mapping == 'a') { 118 dlen = get_acorn_filename(de, tmpname, dir); 119 dpnt = tmpname; 120 } else if (sbi->s_mapping == 'n') { 121 dlen = isofs_name_translate(de, tmpname, dir); 122 dpnt = tmpname; 123 } 124 125 /* 126 * Skip hidden or associated files unless hide or showassoc, 127 * respectively, is set 128 */ 129 match = 0; 130 if (dlen > 0 && 131 (!sbi->s_hide || 132 (!(de->flags[-sbi->s_high_sierra] & 1))) && 133 (sbi->s_showassoc || 134 (!(de->flags[-sbi->s_high_sierra] & 4)))) { 135 if (dpnt && (dlen > 1 || dpnt[0] > 1)) 136 match = (isofs_cmp(dentry, dpnt, dlen) == 0); 137 } 138 if (match) { 139 isofs_normalize_block_and_offset(de, 140 &block_saved, 141 &offset_saved); 142 *block_rv = block_saved; 143 *offset_rv = offset_saved; 144 brelse(bh); 145 return 1; 146 } 147 } 148 brelse(bh); 149 return 0; 150 } 151 152 struct dentry *isofs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) 153 { 154 int found; 155 unsigned long block; 156 unsigned long offset; 157 struct inode *inode; 158 struct page *page; 159 160 page = alloc_page(GFP_USER); 161 if (!page) 162 return ERR_PTR(-ENOMEM); 163 164 found = isofs_find_entry(dir, dentry, 165 &block, &offset, 166 page_address(page), 167 1024 + page_address(page)); 168 __free_page(page); 169 170 inode = found ? isofs_iget(dir->i_sb, block, offset) : NULL; 171 172 return d_splice_alias(inode, dentry); 173 } 174