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