fs/isofs/namei.c

   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
  22         if (!compare)
  23                 return 1;
  24
  25         /* check special "." and ".." files */
  26         if (dlen == 1) {
  27                 /* "." */
  28                 if (compare[0] == 0) {
  29                         if (!dentry->d_name.len)
  30                                 return 0;
  31                         compare = ".";
  32                 } else if (compare[0] == 1) {
  33                         compare = "..";
  34                         dlen = 2;
  35                 }
  36         }
  37
  38         qstr.name = compare;
  39         qstr.len = dlen;
  40         return dentry->d_op->d_compare(dentry, &dentry->d_name, &qstr);
  41 }
  42
  43 /*
  44  *      isofs_find_entry()
  45  *
  46  * finds an entry in the specified directory with the wanted name. It
  47  * returns the inode number of the found entry, or 0 on error.
  48  */
  49 static unsigned long
  50 isofs_find_entry(struct inode *dir, struct dentry *dentry,
  51         unsigned long *block_rv, unsigned long *offset_rv,
  52         char *tmpname, struct iso_directory_record *tmpde)
  53 {
  54         unsigned long bufsize = ISOFS_BUFFER_SIZE(dir);
  55         unsigned char bufbits = ISOFS_BUFFER_BITS(dir);
  56         unsigned long block, f_pos, offset, block_saved, offset_saved;
  57         struct buffer_head *bh = NULL;
  58         struct isofs_sb_info *sbi = ISOFS_SB(dir->i_sb);
  59
  60         if (!ISOFS_I(dir)->i_first_extent)
  61                 return 0;
  62
  63         f_pos = 0;
  64         offset = 0;
  65         block = 0;
  66
  67         while (f_pos < dir->i_size) {
  68                 struct iso_directory_record *de;
  69                 int de_len, match, i, dlen;
  70                 char *dpnt;
  71
  72                 if (!bh) {
  73                         bh = isofs_bread(dir, block);
  74                         if (!bh)
  75                                 return 0;
  76                 }
  77
  78                 de = (struct iso_directory_record *) (bh->b_data + offset);
  79
  80                 de_len = *(unsigned char *) de;
  81                 if (!de_len) {
  82                         brelse(bh);
  83                         bh = NULL;
  84                         f_pos = (f_pos + ISOFS_BLOCK_SIZE) & ~(ISOFS_BLOCK_SIZE - 1);
  85                         block = f_pos >> bufbits;
  86                         offset = 0;
  87                         continue;
  88                 }
  89
  90                 block_saved = bh->b_blocknr;
  91                 offset_saved = offset;
  92                 offset += de_len;
  93                 f_pos += de_len;
  94
  95                 /* Make sure we have a full directory entry */
  96                 if (offset >= bufsize) {
  97                         int slop = bufsize - offset + de_len;
  98                         memcpy(tmpde, de, slop);
  99                         offset &= bufsize - 1;
 100                         block++;
 101                         brelse(bh);
 102                         bh = NULL;
 103                         if (offset) {
 104                                 bh = isofs_bread(dir, block);
 105                                 if (!bh)
 106                                         return 0;
 107                                 memcpy((void *) tmpde + slop, bh->b_data, offset);
 108                         }
 109                         de = tmpde;
 110                 }
 111
 112                 dlen = de->name_len[0];
 113                 dpnt = de->name;
 114                 /* Basic sanity check, whether name doesn't exceed dir entry */
 115                 if (de_len < dlen + sizeof(struct iso_directory_record)) {
 116                         printk(KERN_NOTICE "iso9660: Corrupted directory entry"
 117                                " in block %lu of inode %lu\n", block,
 118                                dir->i_ino);
 119                         return 0;
 120                 }
 121
 122                 if (sbi->s_rock &&
 123                     ((i = get_rock_ridge_filename(de, tmpname, dir)))) {
 124                         dlen = i;       /* possibly -1 */
 125                         dpnt = tmpname;
 126 #ifdef CONFIG_JOLIET
 127                 } else if (sbi->s_joliet_level) {
 128                         dlen = get_joliet_filename(de, tmpname, dir);
 129                         dpnt = tmpname;
 130 #endif
 131                 } else if (sbi->s_mapping == 'a') {
 132                         dlen = get_acorn_filename(de, tmpname, dir);
 133                         dpnt = tmpname;
 134                 } else if (sbi->s_mapping == 'n') {
 135                         dlen = isofs_name_translate(de, tmpname, dir);
 136                         dpnt = tmpname;
 137                 }
 138
 139                 /*
 140                  * Skip hidden or associated files unless hide or showassoc,
 141                  * respectively, is set
 142                  */
 143                 match = 0;
 144                 if (dlen > 0 &&
 145                         (!sbi->s_hide ||
 146                                 (!(de->flags[-sbi->s_high_sierra] & 1))) &&
 147                         (sbi->s_showassoc ||
 148                                 (!(de->flags[-sbi->s_high_sierra] & 4)))) {
 149                         match = (isofs_cmp(dentry, dpnt, dlen) == 0);
 150                 }
 151                 if (match) {
 152                         isofs_normalize_block_and_offset(de,
 153                                                          &block_saved,
 154                                                          &offset_saved);
 155                         *block_rv = block_saved;
 156                         *offset_rv = offset_saved;
 157                         brelse(bh);
 158                         return 1;
 159                 }
 160         }
 161         brelse(bh);
 162         return 0;
 163 }
 164
 165 struct dentry *isofs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 166 {
 167         int found;
 168         unsigned long uninitialized_var(block);
 169         unsigned long uninitialized_var(offset);
 170         struct isofs_sb_info *sbi = ISOFS_SB(dir->i_sb);
 171         struct inode *inode;
 172         struct page *page;
 173
 174         dentry->d_op = dir->i_sb->s_root->d_op;
 175
 176         page = alloc_page(GFP_USER);
 177         if (!page)
 178                 return ERR_PTR(-ENOMEM);
 179
 180         mutex_lock(&sbi->s_mutex);
 181         found = isofs_find_entry(dir, dentry,
 182                                 &block, &offset,
 183                                 page_address(page),
 184                                 1024 + page_address(page));
 185         __free_page(page);
 186
 187         inode = NULL;
 188         if (found) {
 189                 inode = isofs_iget(dir->i_sb, block, offset);
 190                 if (IS_ERR(inode)) {
 191                         mutex_unlock(&sbi->s_mutex);
 192                         return ERR_CAST(inode);
 193                 }
 194         }
 195         mutex_unlock(&sbi->s_mutex);
 196         return d_splice_alias(inode, dentry);
 197 }