fs/isofs/namei.c

   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 uninitialized_var(block);
 156         unsigned long uninitialized_var(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 }