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