reactos/drivers/fs/ntfs/linux-ntfs/namei.c

   1 /*
   2  * namei.c - NTFS kernel directory inode operations. Part of the Linux-NTFS
   3  *           project.
   4  *
   5  * Copyright (c) 2001-2003 Anton Altaparmakov
   6  *
   7  * This program/include file is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License as published
   9  * by the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program/include file is distributed in the hope that it will be
  13  * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
  14  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program (in the main directory of the Linux-NTFS
  19  * distribution in the file COPYING); if not, write to the Free Software
  20  * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21  */
  22
  23 #include <linux/dcache.h>
  24
  25 #include "ntfs.h"
  26 #include "dir.h"
  27
  28 /**
  29  * ntfs_lookup - find the inode represented by a dentry in a directory inode
  30  * @dir_ino:    directory inode in which to look for the inode
  31  * @dent:       dentry representing the inode to look for
  32  * @nd:         lookup nameidata
  33  *
  34  * In short, ntfs_lookup() looks for the inode represented by the dentry @dent
  35  * in the directory inode @dir_ino and if found attaches the inode to the
  36  * dentry @dent.
  37  *
  38  * In more detail, the dentry @dent specifies which inode to look for by
  39  * supplying the name of the inode in @dent->d_name.name. ntfs_lookup()
  40  * converts the name to Unicode and walks the contents of the directory inode
  41  * @dir_ino looking for the converted Unicode name. If the name is found in the
  42  * directory, the corresponding inode is loaded by calling ntfs_iget() on its
  43  * inode number and the inode is associated with the dentry @dent via a call to
  44  * d_add().
  45  *
  46  * If the name is not found in the directory, a NULL inode is inserted into the
  47  * dentry @dent. The dentry is then termed a negative dentry.
  48  *
  49  * Only if an actual error occurs, do we return an error via ERR_PTR().
  50  *
  51  * In order to handle the case insensitivity issues of NTFS with regards to the
  52  * dcache and the dcache requiring only one dentry per directory, we deal with
  53  * dentry aliases that only differ in case in ->ntfs_lookup() while maintining
  54  * a case sensitive dcache. This means that we get the full benefit of dcache
  55  * speed when the file/directory is looked up with the same case as returned by
  56  * ->ntfs_readdir() but that a lookup for any other case (or for the short file
  57  * name) will not find anything in dcache and will enter ->ntfs_lookup()
  58  * instead, where we search the directory for a fully matching file name
  59  * (including case) and if that is not found, we search for a file name that
  60  * matches with different case and if that has non-POSIX semantics we return
  61  * that. We actually do only one search (case sensitive) and keep tabs on
  62  * whether we have found a case insensitive match in the process.
  63  *
  64  * To simplify matters for us, we do not treat the short vs long filenames as
  65  * two hard links but instead if the lookup matches a short filename, we
  66  * return the dentry for the corresponding long filename instead.
  67  *
  68  * There are three cases we need to distinguish here:
  69  *
  70  * 1) @dent perfectly matches (i.e. including case) a directory entry with a
  71  *    file name in the WIN32 or POSIX namespaces. In this case
  72  *    ntfs_lookup_inode_by_name() will return with name set to NULL and we
  73  *    just d_add() @dent.
  74  * 2) @dent matches (not including case) a directory entry with a file name in
  75  *    the WIN32 namespace. In this case ntfs_lookup_inode_by_name() will return
  76  *    with name set to point to a kmalloc()ed ntfs_name structure containing
  77  *    the properly cased little endian Unicode name. We convert the name to the
  78  *    current NLS code page, search if a dentry with this name already exists
  79  *    and if so return that instead of @dent. The VFS will then destroy the old
  80  *    @dent and use the one we returned. If a dentry is not found, we allocate
  81  *    a new one, d_add() it, and return it as above.
  82  * 3) @dent matches either perfectly or not (i.e. we don't care about case) a
  83  *    directory entry with a file name in the DOS namespace. In this case
  84  *    ntfs_lookup_inode_by_name() will return with name set to point to a
  85  *    kmalloc()ed ntfs_name structure containing the mft reference (cpu endian)
  86  *    of the inode. We use the mft reference to read the inode and to find the
  87  *    file name in the WIN32 namespace corresponding to the matched short file
  88  *    name. We then convert the name to the current NLS code page, and proceed
  89  *    searching for a dentry with this name, etc, as in case 2), above.
  90  */
  91 static struct dentry *ntfs_lookup(struct inode *dir_ino, struct dentry *dent, struct nameidata *nd)
  92 {
  93         ntfs_volume *vol = NTFS_SB(dir_ino->i_sb);
  94         struct inode *dent_inode;
  95         uchar_t *uname;
  96         ntfs_name *name = NULL;
  97         MFT_REF mref;
  98         unsigned long dent_ino;
  99         int uname_len;
 100
 101         ntfs_debug("Looking up %s in directory inode 0x%lx.",
 102                         dent->d_name.name, dir_ino->i_ino);
 103         /* Convert the name of the dentry to Unicode. */
 104         uname_len = ntfs_nlstoucs(vol, dent->d_name.name, dent->d_name.len,
 105                         &uname);
 106         if (uname_len < 0) {
 107                 ntfs_error(vol->sb, "Failed to convert name to Unicode.");
 108                 return ERR_PTR(uname_len);
 109         }
 110         mref = ntfs_lookup_inode_by_name(NTFS_I(dir_ino), uname, uname_len,
 111                         &name);
 112         kmem_cache_free(ntfs_name_cache, uname);
 113         if (!IS_ERR_MREF(mref)) {
 114                 dent_ino = MREF(mref);
 115                 ntfs_debug("Found inode 0x%lx. Calling ntfs_iget.", dent_ino);
 116                 dent_inode = ntfs_iget(vol->sb, dent_ino);
 117                 if (likely(!IS_ERR(dent_inode))) {
 118                         /* Consistency check. */
 119                         if (MSEQNO(mref) == NTFS_I(dent_inode)->seq_no ||
 120                                         dent_ino == FILE_MFT) {
 121                                 /* Perfect WIN32/POSIX match. -- Case 1. */
 122                                 if (!name) {
 123                                         d_add(dent, dent_inode);
 124                                         ntfs_debug("Done.");
 125                                         return NULL;
 126                                 }
 127                                 /*
 128                                  * We are too indented. Handle imperfect
 129                                  * matches and short file names further below.
 130                                  */
 131                                 goto handle_name;
 132                         }
 133                         ntfs_error(vol->sb, "Found stale reference to inode "
 134                                         "0x%lx (reference sequence number = "
 135                                         "0x%x, inode sequence number = 0x%x, "
 136                                         "returning -EIO. Run chkdsk.",
 137                                         dent_ino, MSEQNO(mref),
 138                                         NTFS_I(dent_inode)->seq_no);
 139                         iput(dent_inode);
 140                         dent_inode = ERR_PTR(-EIO);
 141                 } else
 142                         ntfs_error(vol->sb, "ntfs_iget(0x%lx) failed with "
 143                                         "error code %li.", dent_ino,
 144                                         PTR_ERR(dent_inode));
 145                 if (name)
 146                         kfree(name);
 147                 /* Return the error code. */
 148                 return (struct dentry *)dent_inode;
 149         }
 150         /* It is guaranteed that name is no longer allocated at this point. */
 151         if (MREF_ERR(mref) == -ENOENT) {
 152                 ntfs_debug("Entry was not found, adding negative dentry.");
 153                 /* The dcache will handle negative entries. */
 154                 d_add(dent, NULL);
 155                 ntfs_debug("Done.");
 156                 return NULL;
 157         }
 158         ntfs_error(vol->sb, "ntfs_lookup_ino_by_name() failed with error "
 159                         "code %i.", -MREF_ERR(mref));
 160         return ERR_PTR(MREF_ERR(mref));
 161
 162         // TODO: Consider moving this lot to a separate function! (AIA)
 163 handle_name:
 164    {
 165         struct dentry *real_dent;
 166         MFT_RECORD *m;
 167         attr_search_context *ctx;
 168         ntfs_inode *ni = NTFS_I(dent_inode);
 169         int err;
 170         struct qstr nls_name;
 171
 172         nls_name.name = NULL;
 173         if (name->type != FILE_NAME_DOS) {                      /* Case 2. */
 174                 nls_name.len = (unsigned)ntfs_ucstonls(vol,
 175                                 (uchar_t*)&name->name, name->len,
 176                                 (unsigned char**)&nls_name.name,
 177                                 name->len * 3 + 1);
 178                 kfree(name);
 179         } else /* if (name->type == FILE_NAME_DOS) */ {         /* Case 3. */
 180                 FILE_NAME_ATTR *fn;
 181
 182                 kfree(name);
 183
 184                 /* Find the WIN32 name corresponding to the matched DOS name. */
 185                 ni = NTFS_I(dent_inode);
 186                 m = map_mft_record(ni);
 187                 if (IS_ERR(m)) {
 188                         err = PTR_ERR(m);
 189                         m = NULL;
 190                         ctx = NULL;
 191                         goto err_out;
 192                 }
 193                 ctx = get_attr_search_ctx(ni, m);
 194                 if (!ctx) {
 195                         err = -ENOMEM;
 196                         goto err_out;
 197                 }
 198                 do {
 199                         ATTR_RECORD *a;
 200                         u32 val_len;
 201
 202                         if (!lookup_attr(AT_FILE_NAME, NULL, 0, 0, 0, NULL, 0,
 203                                         ctx)) {
 204                                 ntfs_error(vol->sb, "Inode corrupt: No WIN32 "
 205                                                 "namespace counterpart to DOS "
 206                                                 "file name. Run chkdsk.");
 207                                 err = -EIO;
 208                                 goto err_out;
 209                         }
 210                         /* Consistency checks. */
 211                         a = ctx->attr;
 212                         if (a->non_resident || a->flags)
 213                                 goto eio_err_out;
 214                         val_len = le32_to_cpu(a->data.resident.value_length);
 215                         if (le16_to_cpu(a->data.resident.value_offset) +
 216                                         val_len > le32_to_cpu(a->length))
 217                                 goto eio_err_out;
 218                         fn = (FILE_NAME_ATTR*)((u8*)ctx->attr + le16_to_cpu(
 219                                         ctx->attr->data.resident.value_offset));
 220                         if ((u32)(fn->file_name_length * sizeof(uchar_t) +
 221                                         sizeof(FILE_NAME_ATTR)) > val_len)
 222                                 goto eio_err_out;
 223                 } while (fn->file_name_type != FILE_NAME_WIN32);
 224
 225                 /* Convert the found WIN32 name to current NLS code page. */
 226                 nls_name.len = (unsigned)ntfs_ucstonls(vol,
 227                                 (uchar_t*)&fn->file_name, fn->file_name_length,
 228                                 (unsigned char**)&nls_name.name,
 229                                 fn->file_name_length * 3 + 1);
 230
 231                 put_attr_search_ctx(ctx);
 232                 unmap_mft_record(ni);
 233         }
 234         m = NULL;
 235         ctx = NULL;
 236
 237         /* Check if a conversion error occurred. */
 238         if ((signed)nls_name.len < 0) {
 239                 err = (signed)nls_name.len;
 240                 goto err_out;
 241         }
 242         nls_name.hash = full_name_hash(nls_name.name, nls_name.len);
 243
 244         /*
 245          * Note: No need for dent->d_lock lock as i_sem is held on the
 246          * parent inode.
 247          */
 248
 249         /* Does a dentry matching the nls_name exist already? */
 250         real_dent = d_lookup(dent->d_parent, &nls_name);
 251         /* If not, create it now. */
 252         if (!real_dent) {
 253                 real_dent = d_alloc(dent->d_parent, &nls_name);
 254                 kfree(nls_name.name);
 255                 if (!real_dent) {
 256                         err = -ENOMEM;
 257                         goto err_out;
 258                 }
 259                 d_add(real_dent, dent_inode);
 260                 return real_dent;
 261         }
 262         kfree(nls_name.name);
 263         /* Matching dentry exists, check if it is negative. */
 264         if (real_dent->d_inode) {
 265                 BUG_ON(real_dent->d_inode != dent_inode);
 266                 /*
 267                  * Already have the inode and the dentry attached, decrement
 268                  * the reference count to balance the ntfs_iget() we did
 269                  * earlier on.
 270                  */
 271                 iput(dent_inode);
 272                 return real_dent;
 273         }
 274         /* Negative dentry: instantiate it. */
 275         d_instantiate(real_dent, dent_inode);
 276         return real_dent;
 277
 278 eio_err_out:
 279         ntfs_error(vol->sb, "Illegal file name attribute. Run chkdsk.");
 280         err = -EIO;
 281 err_out:
 282         if (ctx)
 283                 put_attr_search_ctx(ctx);
 284         if (m)
 285                 unmap_mft_record(ni);
 286         iput(dent_inode);
 287         return ERR_PTR(err);
 288    }
 289 }
 290
 291 /*
 292  * Inode operations for directories.
 293  */
 294 struct inode_operations ntfs_dir_inode_ops = {
 295         .lookup = ntfs_lookup,  /* VFS: Lookup directory. */
 296 };
 297