Line data    Source code

       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           0 : isofs_cmp(struct dentry *dentry, const char *compare, int dlen)
      20             : {
      21           0 :         struct qstr qstr;
      22           0 :         qstr.name = compare;
      23           0 :         qstr.len = dlen;
      24           0 :         if (likely(!dentry->d_op))
      25           0 :                 return dentry->d_name.len != dlen || memcmp(dentry->d_name.name, compare, dlen);
      26           0 :         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           0 : 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           0 :         unsigned long bufsize = ISOFS_BUFFER_SIZE(dir);
      41           0 :         unsigned char bufbits = ISOFS_BUFFER_BITS(dir);
      42           0 :         unsigned long block, f_pos, offset, block_saved, offset_saved;
      43           0 :         struct buffer_head *bh = NULL;
      44           0 :         struct isofs_sb_info *sbi = ISOFS_SB(dir->i_sb);
      45             : 
      46           0 :         if (!ISOFS_I(dir)->i_first_extent)
      47             :                 return 0;
      48             : 
      49             :         f_pos = 0;
      50             :         offset = 0;
      51             :         block = 0;
      52             : 
      53           0 :         while (f_pos < dir->i_size) {
      54           0 :                 struct iso_directory_record *de;
      55           0 :                 int de_len, match, i, dlen;
      56           0 :                 char *dpnt;
      57             : 
      58           0 :                 if (!bh) {
      59           0 :                         bh = isofs_bread(dir, block);
      60           0 :                         if (!bh)
      61             :                                 return 0;
      62             :                 }
      63             : 
      64           0 :                 de = (struct iso_directory_record *) (bh->b_data + offset);
      65             : 
      66           0 :                 de_len = *(unsigned char *) de;
      67           0 :                 if (!de_len) {
      68           0 :                         brelse(bh);
      69           0 :                         bh = NULL;
      70           0 :                         f_pos = (f_pos + ISOFS_BLOCK_SIZE) & ~(ISOFS_BLOCK_SIZE - 1);
      71           0 :                         block = f_pos >> bufbits;
      72           0 :                         offset = 0;
      73           0 :                         continue;
      74             :                 }
      75             : 
      76           0 :                 block_saved = bh->b_blocknr;
      77           0 :                 offset_saved = offset;
      78           0 :                 offset += de_len;
      79           0 :                 f_pos += de_len;
      80             : 
      81             :                 /* Make sure we have a full directory entry */
      82           0 :                 if (offset >= bufsize) {
      83           0 :                         int slop = bufsize - offset + de_len;
      84           0 :                         memcpy(tmpde, de, slop);
      85           0 :                         offset &= bufsize - 1;
      86           0 :                         block++;
      87           0 :                         brelse(bh);
      88           0 :                         bh = NULL;
      89           0 :                         if (offset) {
      90           0 :                                 bh = isofs_bread(dir, block);
      91           0 :                                 if (!bh)
      92             :                                         return 0;
      93           0 :                                 memcpy((void *) tmpde + slop, bh->b_data, offset);
      94             :                         }
      95             :                         de = tmpde;
      96             :                 }
      97             : 
      98           0 :                 dlen = de->name_len[0];
      99           0 :                 dpnt = de->name;
     100             :                 /* Basic sanity check, whether name doesn't exceed dir entry */
     101           0 :                 if (de_len < dlen + sizeof(struct iso_directory_record)) {
     102           0 :                         printk(KERN_NOTICE "iso9660: Corrupted directory entry"
     103             :                                " in block %lu of inode %lu\n", block,
     104             :                                dir->i_ino);
     105           0 :                         brelse(bh);
     106           0 :                         return 0;
     107             :                 }
     108             : 
     109           0 :                 if (sbi->s_rock &&
     110           0 :                     ((i = get_rock_ridge_filename(de, tmpname, dir)))) {
     111             :                         dlen = i;       /* possibly -1 */
     112             :                         dpnt = tmpname;
     113             : #ifdef CONFIG_JOLIET
     114           0 :                 } else if (sbi->s_joliet_level) {
     115           0 :                         dlen = get_joliet_filename(de, tmpname, dir);
     116           0 :                         dpnt = tmpname;
     117             : #endif
     118           0 :                 } else if (sbi->s_mapping == 'a') {
     119           0 :                         dlen = get_acorn_filename(de, tmpname, dir);
     120           0 :                         dpnt = tmpname;
     121           0 :                 } else if (sbi->s_mapping == 'n') {
     122           0 :                         dlen = isofs_name_translate(de, tmpname, dir);
     123           0 :                         dpnt = tmpname;
     124             :                 }
     125             : 
     126             :                 /*
     127             :                  * Skip hidden or associated files unless hide or showassoc,
     128             :                  * respectively, is set
     129             :                  */
     130           0 :                 match = 0;
     131           0 :                 if (dlen > 0 &&
     132           0 :                         (!sbi->s_hide ||
     133           0 :                                 (!(de->flags[-sbi->s_high_sierra] & 1))) &&
     134           0 :                         (sbi->s_showassoc ||
     135           0 :                                 (!(de->flags[-sbi->s_high_sierra] & 4)))) {
     136           0 :                         if (dpnt && (dlen > 1 || dpnt[0] > 1))
     137           0 :                                 match = (isofs_cmp(dentry, dpnt, dlen) == 0);
     138             :                 }
     139           0 :                 if (match) {
     140           0 :                         isofs_normalize_block_and_offset(de,
     141             :                                                          &block_saved,
     142             :                                                          &offset_saved);
     143           0 :                         *block_rv = block_saved;
     144           0 :                         *offset_rv = offset_saved;
     145           0 :                         brelse(bh);
     146           0 :                         return 1;
     147             :                 }
     148             :         }
     149           0 :         brelse(bh);
     150             :         return 0;
     151             : }
     152             : 
     153           0 : struct dentry *isofs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
     154             : {
     155           0 :         int found;
     156           0 :         unsigned long block;
     157           0 :         unsigned long offset;
     158           0 :         struct inode *inode;
     159           0 :         struct page *page;
     160             : 
     161           0 :         page = alloc_page(GFP_USER);
     162           0 :         if (!page)
     163           0 :                 return ERR_PTR(-ENOMEM);
     164             : 
     165           0 :         found = isofs_find_entry(dir, dentry,
     166             :                                 &block, &offset,
     167           0 :                                 page_address(page),
     168           0 :                                 1024 + page_address(page));
     169           0 :         __free_page(page);
     170             : 
     171           0 :         inode = found ? isofs_iget(dir->i_sb, block, offset) : NULL;
     172             : 
     173           0 :         return d_splice_alias(inode, dentry);
     174             : }