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/time.h>
  10 #include <linux/iso_fs.h>
  11 #include <linux/kernel.h>
  12 #include <linux/string.h>
  13 #include <linux/stat.h>
  14 #include <linux/fcntl.h>
  15 #include <linux/mm.h>
  16 #include <linux/errno.h>
  17 #include <linux/config.h>       /* Joliet? */
  18 #include <linux/smp_lock.h>
  19 #include <linux/buffer_head.h>
  20 #include <linux/dcache.h>
  21
  22 #include <asm/uaccess.h>
  23
  24 /*
  25  * ok, we cannot use strncmp, as the name is not in our data space.
  26  * Thus we'll have to use isofs_match. No big problem. Match also makes
  27  * some sanity tests.
  28  */
  29 static int
  30 isofs_cmp(struct dentry * dentry, const char * compare, int dlen)
  31 {
  32         struct qstr qstr;
  33
  34         if (!compare)
  35                 return 1;
  36
  37         /* check special "." and ".." files */
  38         if (dlen == 1) {
  39                 /* "." */
  40                 if (compare[0] == 0) {
  41                         if (!dentry->d_name.len)
  42                                 return 0;
  43                         compare = ".";
  44                 } else if (compare[0] == 1) {
  45                         compare = "..";
  46                         dlen = 2;
  47                 }
  48         }
  49
  50         qstr.name = compare;
  51         qstr.len = dlen;
  52         return dentry->d_op->d_compare(dentry, &dentry->d_name, &qstr);
  53 }
  54
  55 /*
  56  *      isofs_find_entry()
  57  *
  58  * finds an entry in the specified directory with the wanted name. It
  59  * returns the inode number of the found entry, or 0 on error.
  60  */
  61 static unsigned long
  62 isofs_find_entry(struct inode *dir, struct dentry *dentry,
  63         unsigned long *block_rv, unsigned long* offset_rv,
  64         char * tmpname, struct iso_directory_record * tmpde)
  65 {
  66         unsigned long bufsize = ISOFS_BUFFER_SIZE(dir);
  67         unsigned char bufbits = ISOFS_BUFFER_BITS(dir);
  68         unsigned long block, f_pos, offset, block_saved, offset_saved;
  69         struct buffer_head * bh = NULL;
  70         struct isofs_sb_info *sbi = ISOFS_SB(dir->i_sb);
  71
  72         if (!ISOFS_I(dir)->i_first_extent)
  73                 return 0;
  74
  75         f_pos = 0;
  76         offset = 0;
  77         block = 0;
  78
  79         while (f_pos < dir->i_size) {
  80                 struct iso_directory_record * de;
  81                 int de_len, match, i, dlen;
  82                 char *dpnt;
  83
  84                 if (!bh) {
  85                         bh = isofs_bread(dir, block);
  86                         if (!bh)
  87                                 return 0;
  88                 }
  89
  90                 de = (struct iso_directory_record *) (bh->b_data + offset);
  91
  92                 de_len = *(unsigned char *) de;
  93                 if (!de_len) {
  94                         brelse(bh);
  95                         bh = NULL;
  96                         f_pos = (f_pos + ISOFS_BLOCK_SIZE) & ~(ISOFS_BLOCK_SIZE - 1);
  97                         block = f_pos >> bufbits;
  98                         offset = 0;
  99                         continue;
 100                 }
 101
 102                 block_saved = bh->b_blocknr;
 103                 offset_saved = offset;
 104                 offset += de_len;
 105                 f_pos += de_len;
 106
 107                 /* Make sure we have a full directory entry */
 108                 if (offset >= bufsize) {
 109                         int slop = bufsize - offset + de_len;
 110                         memcpy(tmpde, de, slop);
 111                         offset &= bufsize - 1;
 112                         block++;
 113                         brelse(bh);
 114                         bh = NULL;
 115                         if (offset) {
 116                                 bh = isofs_bread(dir, block);
 117                                 if (!bh)
 118                                         return 0;
 119                                 memcpy((void *) tmpde + slop, bh->b_data, offset);
 120                         }
 121                         de = tmpde;
 122                 }
 123
 124                 dlen = de->name_len[0];
 125                 dpnt = de->name;
 126
 127                 if (sbi->s_rock &&
 128                     ((i = get_rock_ridge_filename(de, tmpname, dir)))) {
 129                         dlen = i;       /* possibly -1 */
 130                         dpnt = tmpname;
 131 #ifdef CONFIG_JOLIET
 132                 } else if (sbi->s_joliet_level) {
 133                         dlen = get_joliet_filename(de, tmpname, dir);
 134                         dpnt = tmpname;
 135 #endif
 136                 } else if (sbi->s_mapping == 'a') {
 137                         dlen = get_acorn_filename(de, tmpname, dir);
 138                         dpnt = tmpname;
 139                 } else if (sbi->s_mapping == 'n') {
 140                         dlen = isofs_name_translate(de, tmpname, dir);
 141                         dpnt = tmpname;
 142                 }
 143
 144                 /*
 145                  * Skip hidden or associated files unless unhide is set
 146                  */
 147                 match = 0;
 148                 if (dlen > 0 &&
 149                     (!(de->flags[-sbi->s_high_sierra] & 5)
 150                      || sbi->s_unhide == 'y'))
 151                 {
 152                         match = (isofs_cmp(dentry,dpnt,dlen) == 0);
 153                 }
 154                 if (match) {
 155                         isofs_normalize_block_and_offset(de,
 156                                                          &block_saved,
 157                                                          &offset_saved);
 158                         *block_rv = block_saved;
 159                         *offset_rv = offset_saved;
 160                         if (bh) brelse(bh);
 161                         return 1;
 162                 }
 163         }
 164         if (bh) brelse(bh);
 165         return 0;
 166 }
 167
 168 struct dentry *isofs_lookup(struct inode * dir, struct dentry * dentry, struct nameidata *nd)
 169 {
 170         int found;
 171         unsigned long block, offset;
 172         struct inode *inode;
 173         struct page *page;
 174
 175         dentry->d_op = dir->i_sb->s_root->d_op;
 176
 177         page = alloc_page(GFP_USER);
 178         if (!page)
 179                 return ERR_PTR(-ENOMEM);
 180
 181         lock_kernel();
 182         found = isofs_find_entry(dir, dentry,
 183                                  &block, &offset,
 184                                  page_address(page),
 185                                  1024 + page_address(page));
 186         __free_page(page);
 187
 188         inode = NULL;
 189         if (found) {
 190                 inode = isofs_iget(dir->i_sb, block, offset);
 191                 if (!inode) {
 192                         unlock_kernel();
 193                         return ERR_PTR(-EACCES);
 194                 }
 195         }
 196         unlock_kernel();
 197         if (inode)
 198                 return d_splice_alias(inode, dentry);
 199         d_add(dentry, inode);
 200         return NULL;
 201 }