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 static int 14 isofs_cmp(struct dentry *dentry, const char *compare, int dlen) 15 { 16 if (likely(!dentry->d_op)) 17 return dentry->d_name.len != dlen || memcmp(dentry->d_name.name, compare, dlen); 18 return dentry->d_op->d_compare(NULL, dentry->d_name.len, dentry->d_name.name, 19 &QSTR_LEN(compare, dlen)); 20 } 21 22 /* 23 * isofs_find_entry() 24 * 25 * finds an entry in the specified directory with the wanted name. It 26 * returns the inode number of the found entry, or 0 on error. 27 */ 28 static unsigned long 29 isofs_find_entry(struct inode *dir, struct dentry *dentry, 30 unsigned long *block_rv, unsigned long *offset_rv, 31 char *tmpname, struct iso_directory_record *tmpde) 32 { 33 unsigned long bufsize = ISOFS_BUFFER_SIZE(dir); 34 unsigned char bufbits = ISOFS_BUFFER_BITS(dir); 35 unsigned long block, f_pos, offset, block_saved, offset_saved; 36 struct buffer_head *bh = NULL; 37 struct isofs_sb_info *sbi = ISOFS_SB(dir->i_sb); 38 39 if (!ISOFS_I(dir)->i_first_extent) 40 return 0; 41 42 f_pos = 0; 43 offset = 0; 44 block = 0; 45 46 while (f_pos < dir->i_size) { 47 struct iso_directory_record *de; 48 int de_len, match, i, dlen; 49 char *dpnt; 50 51 if (!bh) { 52 bh = isofs_bread(dir, block); 53 if (!bh) 54 return 0; 55 } 56 57 de = (struct iso_directory_record *) (bh->b_data + offset); 58 59 de_len = *(unsigned char *) de; 60 if (!de_len) { 61 brelse(bh); 62 bh = NULL; 63 f_pos = (f_pos + ISOFS_BLOCK_SIZE) & ~(ISOFS_BLOCK_SIZE - 1); 64 block = f_pos >> bufbits; 65 offset = 0; 66 continue; 67 } 68 69 block_saved = bh->b_blocknr; 70 offset_saved = offset; 71 offset += de_len; 72 f_pos += de_len; 73 74 /* Make sure we have a full directory entry */ 75 if (offset >= bufsize) { 76 int slop = bufsize - offset + de_len; 77 memcpy(tmpde, de, slop); 78 offset &= bufsize - 1; 79 block++; 80 brelse(bh); 81 bh = NULL; 82 if (offset) { 83 bh = isofs_bread(dir, block); 84 if (!bh) 85 return 0; 86 memcpy((void *) tmpde + slop, bh->b_data, offset); 87 } 88 de = tmpde; 89 } 90 91 dlen = de->name_len[0]; 92 dpnt = de->name; 93 /* Basic sanity check, whether name doesn't exceed dir entry */ 94 if (de_len < dlen + sizeof(struct iso_directory_record)) { 95 printk(KERN_NOTICE "iso9660: Corrupted directory entry" 96 " in block %lu of inode %llu\n", block, 97 dir->i_ino); 98 brelse(bh); 99 return 0; 100 } 101 102 if (sbi->s_rock && 103 ((i = get_rock_ridge_filename(de, tmpname, dir)))) { 104 dlen = i; /* possibly -1 */ 105 dpnt = tmpname; 106 #ifdef CONFIG_JOLIET 107 } else if (sbi->s_joliet_level) { 108 dlen = get_joliet_filename(de, tmpname, dir); 109 dpnt = tmpname; 110 #endif 111 } else if (sbi->s_mapping == 'a') { 112 dlen = get_acorn_filename(de, tmpname, dir); 113 dpnt = tmpname; 114 } else if (sbi->s_mapping == 'n') { 115 dlen = isofs_name_translate(de, tmpname, dir); 116 dpnt = tmpname; 117 } 118 119 /* 120 * Skip hidden or associated files unless hide or showassoc, 121 * respectively, is set 122 */ 123 match = 0; 124 if (dlen > 0 && 125 (!sbi->s_hide || 126 (!(de->flags[-sbi->s_high_sierra] & 1))) && 127 (sbi->s_showassoc || 128 (!(de->flags[-sbi->s_high_sierra] & 4)))) { 129 if (dpnt && (dlen > 1 || dpnt[0] > 1)) 130 match = (isofs_cmp(dentry, dpnt, dlen) == 0); 131 } 132 if (match) { 133 isofs_normalize_block_and_offset(de, 134 &block_saved, 135 &offset_saved); 136 *block_rv = block_saved; 137 *offset_rv = offset_saved; 138 brelse(bh); 139 return 1; 140 } 141 } 142 brelse(bh); 143 return 0; 144 } 145 146 struct dentry *isofs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) 147 { 148 int found; 149 unsigned long block; 150 unsigned long offset; 151 struct inode *inode; 152 struct page *page; 153 154 page = alloc_page(GFP_USER); 155 if (!page) 156 return ERR_PTR(-ENOMEM); 157 158 found = isofs_find_entry(dir, dentry, 159 &block, &offset, 160 page_address(page), 161 1024 + page_address(page)); 162 __free_page(page); 163 164 inode = found ? isofs_iget(dir->i_sb, block, offset) : NULL; 165 166 return d_splice_alias(inode, dentry); 167 } 168