namei.c

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/*
 * namei.c - NTFS kernel directory inode operations. Part of the Linux-NTFS
 *       project.
 *
 * Copyright (c) 2001-2006 Anton Altaparmakov
 *
 * This program/include file is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program/include file is distributed in the hope that it will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program (in the main directory of the Linux-NTFS
 * distribution in the file COPYING); if not, write to the Free Software
 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/dcache.h>
#include <linux/exportfs.h>
#include <linux/security.h>
#include <linux/slab.h>

#include "attrib.h"
#include "debug.h"
#include "dir.h"
#include "mft.h"
#include "ntfs.h"

static struct dentry *ntfs_lookup(struct inode *dir_ino, struct dentry *dent,
        unsigned int flags)
{
    ntfs_volume *vol = NTFS_SB(dir_ino->i_sb);
    struct inode *dent_inode;
    ntfschar *uname;
    ntfs_name *name = NULL;
    MFT_REF mref;
    unsigned long dent_ino;
    int uname_len;

    ntfs_debug("Looking up %s in directory inode 0x%lx.",
            dent->d_name.name, dir_ino->i_ino);
    /* Convert the name of the dentry to Unicode. */
    uname_len = ntfs_nlstoucs(vol, dent->d_name.name, dent->d_name.len,
            &uname);
    if (uname_len < 0) {
        if (uname_len != -ENAMETOOLONG)
            ntfs_error(vol->sb, "Failed to convert name to "
                    "Unicode.");
        return ERR_PTR(uname_len);
    }
    mref = ntfs_lookup_inode_by_name(NTFS_I(dir_ino), uname, uname_len,
            &name);
    kmem_cache_free(ntfs_name_cache, uname);
    if (!IS_ERR_MREF(mref)) {
        dent_ino = MREF(mref);
        ntfs_debug("Found inode 0x%lx. Calling ntfs_iget.", dent_ino);
        dent_inode = ntfs_iget(vol->sb, dent_ino);
        if (likely(!IS_ERR(dent_inode))) {
            /* Consistency check. */
            if (is_bad_inode(dent_inode) || MSEQNO(mref) ==
                    NTFS_I(dent_inode)->seq_no ||
                    dent_ino == FILE_MFT) {
                /* Perfect WIN32/POSIX match. -- Case 1. */
                if (!name) {
                    ntfs_debug("Done.  (Case 1.)");
                    return d_splice_alias(dent_inode, dent);
                }
                /*
                 * We are too indented.  Handle imperfect
                 * matches and short file names further below.
                 */
                goto handle_name;
            }
            ntfs_error(vol->sb, "Found stale reference to inode "
                    "0x%lx (reference sequence number = "
                    "0x%x, inode sequence number = 0x%x), "
                    "returning -EIO. Run chkdsk.",
                    dent_ino, MSEQNO(mref),
                    NTFS_I(dent_inode)->seq_no);
            iput(dent_inode);
            dent_inode = ERR_PTR(-EIO);
        } else
            ntfs_error(vol->sb, "ntfs_iget(0x%lx) failed with "
                    "error code %li.", dent_ino,
                    PTR_ERR(dent_inode));
        kfree(name);
        /* Return the error code. */
        return (struct dentry *)dent_inode;
    }
    /* It is guaranteed that @name is no longer allocated at this point. */
    if (MREF_ERR(mref) == -ENOENT) {
        ntfs_debug("Entry was not found, adding negative dentry.");
        /* The dcache will handle negative entries. */
        d_add(dent, NULL);
        ntfs_debug("Done.");
        return NULL;
    }
    ntfs_error(vol->sb, "ntfs_lookup_ino_by_name() failed with error "
            "code %i.", -MREF_ERR(mref));
    return ERR_PTR(MREF_ERR(mref));
    // TODO: Consider moving this lot to a separate function! (AIA)
handle_name:
   {
    MFT_RECORD *m;
    ntfs_attr_search_ctx *ctx;
    ntfs_inode *ni = NTFS_I(dent_inode);
    int err;
    struct qstr nls_name;

    nls_name.name = NULL;
    if (name->type != FILE_NAME_DOS) {          /* Case 2. */
        ntfs_debug("Case 2.");
        nls_name.len = (unsigned)ntfs_ucstonls(vol,
                (ntfschar*)&name->name, name->len,
                (unsigned char**)&nls_name.name, 0);
        kfree(name);
    } else /* if (name->type == FILE_NAME_DOS) */ {     /* Case 3. */
        FILE_NAME_ATTR *fn;

        ntfs_debug("Case 3.");
        kfree(name);

        /* Find the WIN32 name corresponding to the matched DOS name. */
        ni = NTFS_I(dent_inode);
        m = map_mft_record(ni);
        if (IS_ERR(m)) {
            err = PTR_ERR(m);
            m = NULL;
            ctx = NULL;
            goto err_out;
        }
        ctx = ntfs_attr_get_search_ctx(ni, m);
        if (unlikely(!ctx)) {
            err = -ENOMEM;
            goto err_out;
        }
        do {
            ATTR_RECORD *a;
            u32 val_len;

            err = ntfs_attr_lookup(AT_FILE_NAME, NULL, 0, 0, 0,
                    NULL, 0, ctx);
            if (unlikely(err)) {
                ntfs_error(vol->sb, "Inode corrupt: No WIN32 "
                        "namespace counterpart to DOS "
                        "file name. Run chkdsk.");
                if (err == -ENOENT)
                    err = -EIO;
                goto err_out;
            }
            /* Consistency checks. */
            a = ctx->attr;
            if (a->non_resident || a->flags)
                goto eio_err_out;
            val_len = le32_to_cpu(a->data.resident.value_length);
            if (le16_to_cpu(a->data.resident.value_offset) +
                    val_len > le32_to_cpu(a->length))
                goto eio_err_out;
            fn = (FILE_NAME_ATTR*)((u8*)ctx->attr + le16_to_cpu(
                    ctx->attr->data.resident.value_offset));
            if ((u32)(fn->file_name_length * sizeof(ntfschar) +
                    sizeof(FILE_NAME_ATTR)) > val_len)
                goto eio_err_out;
        } while (fn->file_name_type != FILE_NAME_WIN32);

        /* Convert the found WIN32 name to current NLS code page. */
        nls_name.len = (unsigned)ntfs_ucstonls(vol,
                (ntfschar*)&fn->file_name, fn->file_name_length,
                (unsigned char**)&nls_name.name, 0);

        ntfs_attr_put_search_ctx(ctx);
        unmap_mft_record(ni);
    }
    m = NULL;
    ctx = NULL;

    /* Check if a conversion error occurred. */
    if ((signed)nls_name.len < 0) {
        err = (signed)nls_name.len;
        goto err_out;
    }
    nls_name.hash = full_name_hash(nls_name.name, nls_name.len);

    dent = d_add_ci(dent, dent_inode, &nls_name);
    kfree(nls_name.name);
    return dent;

eio_err_out:
    ntfs_error(vol->sb, "Illegal file name attribute. Run chkdsk.");
    err = -EIO;
err_out:
    if (ctx)
        ntfs_attr_put_search_ctx(ctx);
    if (m)
        unmap_mft_record(ni);
    iput(dent_inode);
    ntfs_error(vol->sb, "Failed, returning error code %i.", err);
    return ERR_PTR(err);
   }
}

const struct inode_operations ntfs_dir_inode_ops = {
    .lookup = ntfs_lookup,  /* VFS: Lookup directory. */
};

static struct dentry *ntfs_get_parent(struct dentry *child_dent)
{
    struct inode *vi = child_dent->d_inode;
    ntfs_inode *ni = NTFS_I(vi);
    MFT_RECORD *mrec;
    ntfs_attr_search_ctx *ctx;
    ATTR_RECORD *attr;
    FILE_NAME_ATTR *fn;
    unsigned long parent_ino;
    int err;

    ntfs_debug("Entering for inode 0x%lx.", vi->i_ino);
    /* Get the mft record of the inode belonging to the child dentry. */
    mrec = map_mft_record(ni);
    if (IS_ERR(mrec))
        return (struct dentry *)mrec;
    /* Find the first file name attribute in the mft record. */
    ctx = ntfs_attr_get_search_ctx(ni, mrec);
    if (unlikely(!ctx)) {
        unmap_mft_record(ni);
        return ERR_PTR(-ENOMEM);
    }
try_next:
    err = ntfs_attr_lookup(AT_FILE_NAME, NULL, 0, CASE_SENSITIVE, 0, NULL,
            0, ctx);
    if (unlikely(err)) {
        ntfs_attr_put_search_ctx(ctx);
        unmap_mft_record(ni);
        if (err == -ENOENT)
            ntfs_error(vi->i_sb, "Inode 0x%lx does not have a "
                    "file name attribute.  Run chkdsk.",
                    vi->i_ino);
        return ERR_PTR(err);
    }
    attr = ctx->attr;
    if (unlikely(attr->non_resident))
        goto try_next;
    fn = (FILE_NAME_ATTR *)((u8 *)attr +
            le16_to_cpu(attr->data.resident.value_offset));
    if (unlikely((u8 *)fn + le32_to_cpu(attr->data.resident.value_length) >
            (u8*)attr + le32_to_cpu(attr->length)))
        goto try_next;
    /* Get the inode number of the parent directory. */
    parent_ino = MREF_LE(fn->parent_directory);
    /* Release the search context and the mft record of the child. */
    ntfs_attr_put_search_ctx(ctx);
    unmap_mft_record(ni);

    return d_obtain_alias(ntfs_iget(vi->i_sb, parent_ino));
}

static struct inode *ntfs_nfs_get_inode(struct super_block *sb,
        u64 ino, u32 generation)
{
    struct inode *inode;

    inode = ntfs_iget(sb, ino);
    if (!IS_ERR(inode)) {
        if (is_bad_inode(inode) || inode->i_generation != generation) {
            iput(inode);
            inode = ERR_PTR(-ESTALE);
        }
    }

    return inode;
}

static struct dentry *ntfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
        int fh_len, int fh_type)
{
    return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
                    ntfs_nfs_get_inode);
}

static struct dentry *ntfs_fh_to_parent(struct super_block *sb, struct fid *fid,
        int fh_len, int fh_type)
{
    return generic_fh_to_parent(sb, fid, fh_len, fh_type,
                    ntfs_nfs_get_inode);
}

const struct export_operations ntfs_export_ops = {
    .get_parent = ntfs_get_parent,  /* Find the parent of a given
                           directory. */
    .fh_to_dentry   = ntfs_fh_to_dentry,
    .fh_to_parent   = ntfs_fh_to_parent,
};