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attrib.c
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attrib.c
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/**
* attrib.c - NTFS attribute operations. Part of the Linux-NTFS project.
*
* Copyright (c) 2001-2005 Anton Altaparmakov
* Copyright (c) 2002 Richard Russon
*
* 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/buffer_head.h>
#include <linux/swap.h>
#include "attrib.h"
#include "debug.h"
#include "layout.h"
#include "lcnalloc.h"
#include "malloc.h"
#include "mft.h"
#include "ntfs.h"
#include "types.h"
/**
* ntfs_map_runlist_nolock - map (a part of) a runlist of an ntfs inode
* @ni: ntfs inode for which to map (part of) a runlist
* @vcn: map runlist part containing this vcn
*
* Map the part of a runlist containing the @vcn of the ntfs inode @ni.
*
* Return 0 on success and -errno on error. There is one special error code
* which is not an error as such. This is -ENOENT. It means that @vcn is out
* of bounds of the runlist.
*
* Locking: - The runlist must be locked for writing.
* - This function modifies the runlist.
*/
int ntfs_map_runlist_nolock(ntfs_inode *ni, VCN vcn)
{
VCN end_vcn;
ntfs_inode *base_ni;
MFT_RECORD *m;
ATTR_RECORD *a;
ntfs_attr_search_ctx *ctx;
runlist_element *rl;
int err = 0;
ntfs_debug("Mapping runlist part containing vcn 0x%llx.",
(unsigned long long)vcn);
if (!NInoAttr(ni))
base_ni = ni;
else
base_ni = ni->ext.base_ntfs_ino;
m = map_mft_record(base_ni);
if (IS_ERR(m))
return PTR_ERR(m);
ctx = ntfs_attr_get_search_ctx(base_ni, m);
if (unlikely(!ctx)) {
err = -ENOMEM;
goto err_out;
}
err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
CASE_SENSITIVE, vcn, NULL, 0, ctx);
if (unlikely(err)) {
if (err == -ENOENT)
err = -EIO;
goto err_out;
}
a = ctx->attr;
/*
* Only decompress the mapping pairs if @vcn is inside it. Otherwise
* we get into problems when we try to map an out of bounds vcn because
* we then try to map the already mapped runlist fragment and
* ntfs_mapping_pairs_decompress() fails.
*/
end_vcn = sle64_to_cpu(a->data.non_resident.highest_vcn) + 1;
if (unlikely(!a->data.non_resident.lowest_vcn && end_vcn <= 1))
end_vcn = ni->allocated_size >> ni->vol->cluster_size_bits;
if (unlikely(vcn >= end_vcn)) {
err = -ENOENT;
goto err_out;
}
rl = ntfs_mapping_pairs_decompress(ni->vol, a, ni->runlist.rl);
if (IS_ERR(rl))
err = PTR_ERR(rl);
else
ni->runlist.rl = rl;
err_out:
if (likely(ctx))
ntfs_attr_put_search_ctx(ctx);
unmap_mft_record(base_ni);
return err;
}
/**
* ntfs_map_runlist - map (a part of) a runlist of an ntfs inode
* @ni: ntfs inode for which to map (part of) a runlist
* @vcn: map runlist part containing this vcn
*
* Map the part of a runlist containing the @vcn of the ntfs inode @ni.
*
* Return 0 on success and -errno on error. There is one special error code
* which is not an error as such. This is -ENOENT. It means that @vcn is out
* of bounds of the runlist.
*
* Locking: - The runlist must be unlocked on entry and is unlocked on return.
* - This function takes the runlist lock for writing and modifies the
* runlist.
*/
int ntfs_map_runlist(ntfs_inode *ni, VCN vcn)
{
int err = 0;
down_write(&ni->runlist.lock);
/* Make sure someone else didn't do the work while we were sleeping. */
if (likely(ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn) <=
LCN_RL_NOT_MAPPED))
err = ntfs_map_runlist_nolock(ni, vcn);
up_write(&ni->runlist.lock);
return err;
}
/**
* ntfs_attr_vcn_to_lcn_nolock - convert a vcn into a lcn given an ntfs inode
* @ni: ntfs inode of the attribute whose runlist to search
* @vcn: vcn to convert
* @write_locked: true if the runlist is locked for writing
*
* Find the virtual cluster number @vcn in the runlist of the ntfs attribute
* described by the ntfs inode @ni and return the corresponding logical cluster
* number (lcn).
*
* If the @vcn is not mapped yet, the attempt is made to map the attribute
* extent containing the @vcn and the vcn to lcn conversion is retried.
*
* If @write_locked is true the caller has locked the runlist for writing and
* if false for reading.
*
* Since lcns must be >= 0, we use negative return codes with special meaning:
*
* Return code Meaning / Description
* ==========================================
* LCN_HOLE Hole / not allocated on disk.
* LCN_ENOENT There is no such vcn in the runlist, i.e. @vcn is out of bounds.
* LCN_ENOMEM Not enough memory to map runlist.
* LCN_EIO Critical error (runlist/file is corrupt, i/o error, etc).
*
* Locking: - The runlist must be locked on entry and is left locked on return.
* - If @write_locked is FALSE, i.e. the runlist is locked for reading,
* the lock may be dropped inside the function so you cannot rely on
* the runlist still being the same when this function returns.
*/
LCN ntfs_attr_vcn_to_lcn_nolock(ntfs_inode *ni, const VCN vcn,
const BOOL write_locked)
{
LCN lcn;
BOOL is_retry = FALSE;
ntfs_debug("Entering for i_ino 0x%lx, vcn 0x%llx, %s_locked.",
ni->mft_no, (unsigned long long)vcn,
write_locked ? "write" : "read");
BUG_ON(!ni);
BUG_ON(!NInoNonResident(ni));
BUG_ON(vcn < 0);
retry_remap:
/* Convert vcn to lcn. If that fails map the runlist and retry once. */
lcn = ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn);
if (likely(lcn >= LCN_HOLE)) {
ntfs_debug("Done, lcn 0x%llx.", (long long)lcn);
return lcn;
}
if (lcn != LCN_RL_NOT_MAPPED) {
if (lcn != LCN_ENOENT)
lcn = LCN_EIO;
} else if (!is_retry) {
int err;
if (!write_locked) {
up_read(&ni->runlist.lock);
down_write(&ni->runlist.lock);
if (unlikely(ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn) !=
LCN_RL_NOT_MAPPED)) {
up_write(&ni->runlist.lock);
down_read(&ni->runlist.lock);
goto retry_remap;
}
}
err = ntfs_map_runlist_nolock(ni, vcn);
if (!write_locked) {
up_write(&ni->runlist.lock);
down_read(&ni->runlist.lock);
}
if (likely(!err)) {
is_retry = TRUE;
goto retry_remap;
}
if (err == -ENOENT)
lcn = LCN_ENOENT;
else if (err == -ENOMEM)
lcn = LCN_ENOMEM;
else
lcn = LCN_EIO;
}
if (lcn != LCN_ENOENT)
ntfs_error(ni->vol->sb, "Failed with error code %lli.",
(long long)lcn);
return lcn;
}
/**
* ntfs_attr_find_vcn_nolock - find a vcn in the runlist of an ntfs inode
* @ni: ntfs inode describing the runlist to search
* @vcn: vcn to find
* @write_locked: true if the runlist is locked for writing
*
* Find the virtual cluster number @vcn in the runlist described by the ntfs
* inode @ni and return the address of the runlist element containing the @vcn.
*
* If the @vcn is not mapped yet, the attempt is made to map the attribute
* extent containing the @vcn and the vcn to lcn conversion is retried.
*
* If @write_locked is true the caller has locked the runlist for writing and
* if false for reading.
*
* Note you need to distinguish between the lcn of the returned runlist element
* being >= 0 and LCN_HOLE. In the later case you have to return zeroes on
* read and allocate clusters on write.
*
* Return the runlist element containing the @vcn on success and
* ERR_PTR(-errno) on error. You need to test the return value with IS_ERR()
* to decide if the return is success or failure and PTR_ERR() to get to the
* error code if IS_ERR() is true.
*
* The possible error return codes are:
* -ENOENT - No such vcn in the runlist, i.e. @vcn is out of bounds.
* -ENOMEM - Not enough memory to map runlist.
* -EIO - Critical error (runlist/file is corrupt, i/o error, etc).
*
* Locking: - The runlist must be locked on entry and is left locked on return.
* - If @write_locked is FALSE, i.e. the runlist is locked for reading,
* the lock may be dropped inside the function so you cannot rely on
* the runlist still being the same when this function returns.
*/
runlist_element *ntfs_attr_find_vcn_nolock(ntfs_inode *ni, const VCN vcn,
const BOOL write_locked)
{
runlist_element *rl;
int err = 0;
BOOL is_retry = FALSE;
ntfs_debug("Entering for i_ino 0x%lx, vcn 0x%llx, %s_locked.",
ni->mft_no, (unsigned long long)vcn,
write_locked ? "write" : "read");
BUG_ON(!ni);
BUG_ON(!NInoNonResident(ni));
BUG_ON(vcn < 0);
retry_remap:
rl = ni->runlist.rl;
if (likely(rl && vcn >= rl[0].vcn)) {
while (likely(rl->length)) {
if (unlikely(vcn < rl[1].vcn)) {
if (likely(rl->lcn >= LCN_HOLE)) {
ntfs_debug("Done.");
return rl;
}
break;
}
rl++;
}
if (likely(rl->lcn != LCN_RL_NOT_MAPPED)) {
if (likely(rl->lcn == LCN_ENOENT))
err = -ENOENT;
else
err = -EIO;
}
}
if (!err && !is_retry) {
/*
* The @vcn is in an unmapped region, map the runlist and
* retry.
*/
if (!write_locked) {
up_read(&ni->runlist.lock);
down_write(&ni->runlist.lock);
if (unlikely(ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn) !=
LCN_RL_NOT_MAPPED)) {
up_write(&ni->runlist.lock);
down_read(&ni->runlist.lock);
goto retry_remap;
}
}
err = ntfs_map_runlist_nolock(ni, vcn);
if (!write_locked) {
up_write(&ni->runlist.lock);
down_read(&ni->runlist.lock);
}
if (likely(!err)) {
is_retry = TRUE;
goto retry_remap;
}
/*
* -EINVAL coming from a failed mapping attempt is equivalent
* to i/o error for us as it should not happen in our code
* paths.
*/
if (err == -EINVAL)
err = -EIO;
} else if (!err)
err = -EIO;
if (err != -ENOENT)
ntfs_error(ni->vol->sb, "Failed with error code %i.", err);
return ERR_PTR(err);
}
/**
* ntfs_attr_find - find (next) attribute in mft record
* @type: attribute type to find
* @name: attribute name to find (optional, i.e. NULL means don't care)
* @name_len: attribute name length (only needed if @name present)
* @ic: IGNORE_CASE or CASE_SENSITIVE (ignored if @name not present)
* @val: attribute value to find (optional, resident attributes only)
* @val_len: attribute value length
* @ctx: search context with mft record and attribute to search from
*
* You should not need to call this function directly. Use ntfs_attr_lookup()
* instead.
*
* ntfs_attr_find() takes a search context @ctx as parameter and searches the
* mft record specified by @ctx->mrec, beginning at @ctx->attr, for an
* attribute of @type, optionally @name and @val.
*
* If the attribute is found, ntfs_attr_find() returns 0 and @ctx->attr will
* point to the found attribute.
*
* If the attribute is not found, ntfs_attr_find() returns -ENOENT and
* @ctx->attr will point to the attribute before which the attribute being
* searched for would need to be inserted if such an action were to be desired.
*
* On actual error, ntfs_attr_find() returns -EIO. In this case @ctx->attr is
* undefined and in particular do not rely on it not changing.
*
* If @ctx->is_first is TRUE, the search begins with @ctx->attr itself. If it
* is FALSE, the search begins after @ctx->attr.
*
* If @ic is IGNORE_CASE, the @name comparisson is not case sensitive and
* @ctx->ntfs_ino must be set to the ntfs inode to which the mft record
* @ctx->mrec belongs. This is so we can get at the ntfs volume and hence at
* the upcase table. If @ic is CASE_SENSITIVE, the comparison is case
* sensitive. When @name is present, @name_len is the @name length in Unicode
* characters.
*
* If @name is not present (NULL), we assume that the unnamed attribute is
* being searched for.
*
* Finally, the resident attribute value @val is looked for, if present. If
* @val is not present (NULL), @val_len is ignored.
*
* ntfs_attr_find() only searches the specified mft record and it ignores the
* presence of an attribute list attribute (unless it is the one being searched
* for, obviously). If you need to take attribute lists into consideration,
* use ntfs_attr_lookup() instead (see below). This also means that you cannot
* use ntfs_attr_find() to search for extent records of non-resident
* attributes, as extents with lowest_vcn != 0 are usually described by the
* attribute list attribute only. - Note that it is possible that the first
* extent is only in the attribute list while the last extent is in the base
* mft record, so do not rely on being able to find the first extent in the
* base mft record.
*
* Warning: Never use @val when looking for attribute types which can be
* non-resident as this most likely will result in a crash!
*/
static int ntfs_attr_find(const ATTR_TYPE type, const ntfschar *name,
const u32 name_len, const IGNORE_CASE_BOOL ic,
const u8 *val, const u32 val_len, ntfs_attr_search_ctx *ctx)
{
ATTR_RECORD *a;
ntfs_volume *vol = ctx->ntfs_ino->vol;
ntfschar *upcase = vol->upcase;
u32 upcase_len = vol->upcase_len;
/*
* Iterate over attributes in mft record starting at @ctx->attr, or the
* attribute following that, if @ctx->is_first is TRUE.
*/
if (ctx->is_first) {
a = ctx->attr;
ctx->is_first = FALSE;
} else
a = (ATTR_RECORD*)((u8*)ctx->attr +
le32_to_cpu(ctx->attr->length));
for (;; a = (ATTR_RECORD*)((u8*)a + le32_to_cpu(a->length))) {
if ((u8*)a < (u8*)ctx->mrec || (u8*)a > (u8*)ctx->mrec +
le32_to_cpu(ctx->mrec->bytes_allocated))
break;
ctx->attr = a;
if (unlikely(le32_to_cpu(a->type) > le32_to_cpu(type) ||
a->type == AT_END))
return -ENOENT;
if (unlikely(!a->length))
break;
if (a->type != type)
continue;
/*
* If @name is present, compare the two names. If @name is
* missing, assume we want an unnamed attribute.
*/
if (!name) {
/* The search failed if the found attribute is named. */
if (a->name_length)
return -ENOENT;
} else if (!ntfs_are_names_equal(name, name_len,
(ntfschar*)((u8*)a + le16_to_cpu(a->name_offset)),
a->name_length, ic, upcase, upcase_len)) {
register int rc;
rc = ntfs_collate_names(name, name_len,
(ntfschar*)((u8*)a +
le16_to_cpu(a->name_offset)),
a->name_length, 1, IGNORE_CASE,
upcase, upcase_len);
/*
* If @name collates before a->name, there is no
* matching attribute.
*/
if (rc == -1)
return -ENOENT;
/* If the strings are not equal, continue search. */
if (rc)
continue;
rc = ntfs_collate_names(name, name_len,
(ntfschar*)((u8*)a +
le16_to_cpu(a->name_offset)),
a->name_length, 1, CASE_SENSITIVE,
upcase, upcase_len);
if (rc == -1)
return -ENOENT;
if (rc)
continue;
}
/*
* The names match or @name not present and attribute is
* unnamed. If no @val specified, we have found the attribute
* and are done.
*/
if (!val)
return 0;
/* @val is present; compare values. */
else {
register int rc;
rc = memcmp(val, (u8*)a + le16_to_cpu(
a->data.resident.value_offset),
min_t(u32, val_len, le32_to_cpu(
a->data.resident.value_length)));
/*
* If @val collates before the current attribute's
* value, there is no matching attribute.
*/
if (!rc) {
register u32 avl;
avl = le32_to_cpu(
a->data.resident.value_length);
if (val_len == avl)
return 0;
if (val_len < avl)
return -ENOENT;
} else if (rc < 0)
return -ENOENT;
}
}
ntfs_error(vol->sb, "Inode is corrupt. Run chkdsk.");
NVolSetErrors(vol);
return -EIO;
}
/**
* load_attribute_list - load an attribute list into memory
* @vol: ntfs volume from which to read
* @runlist: runlist of the attribute list
* @al_start: destination buffer
* @size: size of the destination buffer in bytes
* @initialized_size: initialized size of the attribute list
*
* Walk the runlist @runlist and load all clusters from it copying them into
* the linear buffer @al. The maximum number of bytes copied to @al is @size
* bytes. Note, @size does not need to be a multiple of the cluster size. If
* @initialized_size is less than @size, the region in @al between
* @initialized_size and @size will be zeroed and not read from disk.
*
* Return 0 on success or -errno on error.
*/
int load_attribute_list(ntfs_volume *vol, runlist *runlist, u8 *al_start,
const s64 size, const s64 initialized_size)
{
LCN lcn;
u8 *al = al_start;
u8 *al_end = al + initialized_size;
runlist_element *rl;
struct buffer_head *bh;
struct super_block *sb;
unsigned long block_size;
unsigned long block, max_block;
int err = 0;
unsigned char block_size_bits;
ntfs_debug("Entering.");
if (!vol || !runlist || !al || size <= 0 || initialized_size < 0 ||
initialized_size > size)
return -EINVAL;
if (!initialized_size) {
memset(al, 0, size);
return 0;
}
sb = vol->sb;
block_size = sb->s_blocksize;
block_size_bits = sb->s_blocksize_bits;
down_read(&runlist->lock);
rl = runlist->rl;
/* Read all clusters specified by the runlist one run at a time. */
while (rl->length) {
lcn = ntfs_rl_vcn_to_lcn(rl, rl->vcn);
ntfs_debug("Reading vcn = 0x%llx, lcn = 0x%llx.",
(unsigned long long)rl->vcn,
(unsigned long long)lcn);
/* The attribute list cannot be sparse. */
if (lcn < 0) {
ntfs_error(sb, "ntfs_rl_vcn_to_lcn() failed. Cannot "
"read attribute list.");
goto err_out;
}
block = lcn << vol->cluster_size_bits >> block_size_bits;
/* Read the run from device in chunks of block_size bytes. */
max_block = block + (rl->length << vol->cluster_size_bits >>
block_size_bits);
ntfs_debug("max_block = 0x%lx.", max_block);
do {
ntfs_debug("Reading block = 0x%lx.", block);
bh = sb_bread(sb, block);
if (!bh) {
ntfs_error(sb, "sb_bread() failed. Cannot "
"read attribute list.");
goto err_out;
}
if (al + block_size >= al_end)
goto do_final;
memcpy(al, bh->b_data, block_size);
brelse(bh);
al += block_size;
} while (++block < max_block);
rl++;
}
if (initialized_size < size) {
initialize:
memset(al_start + initialized_size, 0, size - initialized_size);
}
done:
up_read(&runlist->lock);
return err;
do_final:
if (al < al_end) {
/*
* Partial block.
*
* Note: The attribute list can be smaller than its allocation
* by multiple clusters. This has been encountered by at least
* two people running Windows XP, thus we cannot do any
* truncation sanity checking here. (AIA)
*/
memcpy(al, bh->b_data, al_end - al);
brelse(bh);
if (initialized_size < size)
goto initialize;
goto done;
}
brelse(bh);
/* Real overflow! */
ntfs_error(sb, "Attribute list buffer overflow. Read attribute list "
"is truncated.");
err_out:
err = -EIO;
goto done;
}
/**
* ntfs_external_attr_find - find an attribute in the attribute list of an inode
* @type: attribute type to find
* @name: attribute name to find (optional, i.e. NULL means don't care)
* @name_len: attribute name length (only needed if @name present)
* @ic: IGNORE_CASE or CASE_SENSITIVE (ignored if @name not present)
* @lowest_vcn: lowest vcn to find (optional, non-resident attributes only)
* @val: attribute value to find (optional, resident attributes only)
* @val_len: attribute value length
* @ctx: search context with mft record and attribute to search from
*
* You should not need to call this function directly. Use ntfs_attr_lookup()
* instead.
*
* Find an attribute by searching the attribute list for the corresponding
* attribute list entry. Having found the entry, map the mft record if the
* attribute is in a different mft record/inode, ntfs_attr_find() the attribute
* in there and return it.
*
* On first search @ctx->ntfs_ino must be the base mft record and @ctx must
* have been obtained from a call to ntfs_attr_get_search_ctx(). On subsequent
* calls @ctx->ntfs_ino can be any extent inode, too (@ctx->base_ntfs_ino is
* then the base inode).
*
* After finishing with the attribute/mft record you need to call
* ntfs_attr_put_search_ctx() to cleanup the search context (unmapping any
* mapped inodes, etc).
*
* If the attribute is found, ntfs_external_attr_find() returns 0 and
* @ctx->attr will point to the found attribute. @ctx->mrec will point to the
* mft record in which @ctx->attr is located and @ctx->al_entry will point to
* the attribute list entry for the attribute.
*
* If the attribute is not found, ntfs_external_attr_find() returns -ENOENT and
* @ctx->attr will point to the attribute in the base mft record before which
* the attribute being searched for would need to be inserted if such an action
* were to be desired. @ctx->mrec will point to the mft record in which
* @ctx->attr is located and @ctx->al_entry will point to the attribute list
* entry of the attribute before which the attribute being searched for would
* need to be inserted if such an action were to be desired.
*
* Thus to insert the not found attribute, one wants to add the attribute to
* @ctx->mrec (the base mft record) and if there is not enough space, the
* attribute should be placed in a newly allocated extent mft record. The
* attribute list entry for the inserted attribute should be inserted in the
* attribute list attribute at @ctx->al_entry.
*
* On actual error, ntfs_external_attr_find() returns -EIO. In this case
* @ctx->attr is undefined and in particular do not rely on it not changing.
*/
static int ntfs_external_attr_find(const ATTR_TYPE type,
const ntfschar *name, const u32 name_len,
const IGNORE_CASE_BOOL ic, const VCN lowest_vcn,
const u8 *val, const u32 val_len, ntfs_attr_search_ctx *ctx)
{
ntfs_inode *base_ni, *ni;
ntfs_volume *vol;
ATTR_LIST_ENTRY *al_entry, *next_al_entry;
u8 *al_start, *al_end;
ATTR_RECORD *a;
ntfschar *al_name;
u32 al_name_len;
int err = 0;
static const char *es = " Unmount and run chkdsk.";
ni = ctx->ntfs_ino;
base_ni = ctx->base_ntfs_ino;
ntfs_debug("Entering for inode 0x%lx, type 0x%x.", ni->mft_no, type);
if (!base_ni) {
/* First call happens with the base mft record. */
base_ni = ctx->base_ntfs_ino = ctx->ntfs_ino;
ctx->base_mrec = ctx->mrec;
}
if (ni == base_ni)
ctx->base_attr = ctx->attr;
if (type == AT_END)
goto not_found;
vol = base_ni->vol;
al_start = base_ni->attr_list;
al_end = al_start + base_ni->attr_list_size;
if (!ctx->al_entry)
ctx->al_entry = (ATTR_LIST_ENTRY*)al_start;
/*
* Iterate over entries in attribute list starting at @ctx->al_entry,
* or the entry following that, if @ctx->is_first is TRUE.
*/
if (ctx->is_first) {
al_entry = ctx->al_entry;
ctx->is_first = FALSE;
} else
al_entry = (ATTR_LIST_ENTRY*)((u8*)ctx->al_entry +
le16_to_cpu(ctx->al_entry->length));
for (;; al_entry = next_al_entry) {
/* Out of bounds check. */
if ((u8*)al_entry < base_ni->attr_list ||
(u8*)al_entry > al_end)
break; /* Inode is corrupt. */
ctx->al_entry = al_entry;
/* Catch the end of the attribute list. */
if ((u8*)al_entry == al_end)
goto not_found;
if (!al_entry->length)
break;
if ((u8*)al_entry + 6 > al_end || (u8*)al_entry +
le16_to_cpu(al_entry->length) > al_end)
break;
next_al_entry = (ATTR_LIST_ENTRY*)((u8*)al_entry +
le16_to_cpu(al_entry->length));
if (le32_to_cpu(al_entry->type) > le32_to_cpu(type))
goto not_found;
if (type != al_entry->type)
continue;
/*
* If @name is present, compare the two names. If @name is
* missing, assume we want an unnamed attribute.
*/
al_name_len = al_entry->name_length;
al_name = (ntfschar*)((u8*)al_entry + al_entry->name_offset);
if (!name) {
if (al_name_len)
goto not_found;
} else if (!ntfs_are_names_equal(al_name, al_name_len, name,
name_len, ic, vol->upcase, vol->upcase_len)) {
register int rc;
rc = ntfs_collate_names(name, name_len, al_name,
al_name_len, 1, IGNORE_CASE,
vol->upcase, vol->upcase_len);
/*
* If @name collates before al_name, there is no
* matching attribute.
*/
if (rc == -1)
goto not_found;
/* If the strings are not equal, continue search. */
if (rc)
continue;
/*
* FIXME: Reverse engineering showed 0, IGNORE_CASE but
* that is inconsistent with ntfs_attr_find(). The
* subsequent rc checks were also different. Perhaps I
* made a mistake in one of the two. Need to recheck
* which is correct or at least see what is going on...
* (AIA)
*/
rc = ntfs_collate_names(name, name_len, al_name,
al_name_len, 1, CASE_SENSITIVE,
vol->upcase, vol->upcase_len);
if (rc == -1)
goto not_found;
if (rc)
continue;
}
/*
* The names match or @name not present and attribute is
* unnamed. Now check @lowest_vcn. Continue search if the
* next attribute list entry still fits @lowest_vcn. Otherwise
* we have reached the right one or the search has failed.
*/
if (lowest_vcn && (u8*)next_al_entry >= al_start &&
(u8*)next_al_entry + 6 < al_end &&
(u8*)next_al_entry + le16_to_cpu(
next_al_entry->length) <= al_end &&
sle64_to_cpu(next_al_entry->lowest_vcn) <=
lowest_vcn &&
next_al_entry->type == al_entry->type &&
next_al_entry->name_length == al_name_len &&
ntfs_are_names_equal((ntfschar*)((u8*)
next_al_entry +
next_al_entry->name_offset),
next_al_entry->name_length,
al_name, al_name_len, CASE_SENSITIVE,
vol->upcase, vol->upcase_len))
continue;
if (MREF_LE(al_entry->mft_reference) == ni->mft_no) {
if (MSEQNO_LE(al_entry->mft_reference) != ni->seq_no) {
ntfs_error(vol->sb, "Found stale mft "
"reference in attribute list "
"of base inode 0x%lx.%s",
base_ni->mft_no, es);
err = -EIO;
break;
}
} else { /* Mft references do not match. */
/* If there is a mapped record unmap it first. */
if (ni != base_ni)
unmap_extent_mft_record(ni);
/* Do we want the base record back? */
if (MREF_LE(al_entry->mft_reference) ==
base_ni->mft_no) {
ni = ctx->ntfs_ino = base_ni;
ctx->mrec = ctx->base_mrec;
} else {
/* We want an extent record. */
ctx->mrec = map_extent_mft_record(base_ni,
le64_to_cpu(
al_entry->mft_reference), &ni);
if (IS_ERR(ctx->mrec)) {
ntfs_error(vol->sb, "Failed to map "
"extent mft record "
"0x%lx of base inode "
"0x%lx.%s",
MREF_LE(al_entry->
mft_reference),
base_ni->mft_no, es);
err = PTR_ERR(ctx->mrec);
if (err == -ENOENT)
err = -EIO;
/* Cause @ctx to be sanitized below. */
ni = NULL;
break;
}
ctx->ntfs_ino = ni;
}
ctx->attr = (ATTR_RECORD*)((u8*)ctx->mrec +
le16_to_cpu(ctx->mrec->attrs_offset));
}
/*
* ctx->vfs_ino, ctx->mrec, and ctx->attr now point to the
* mft record containing the attribute represented by the
* current al_entry.
*/
/*
* We could call into ntfs_attr_find() to find the right
* attribute in this mft record but this would be less
* efficient and not quite accurate as ntfs_attr_find() ignores
* the attribute instance numbers for example which become
* important when one plays with attribute lists. Also,
* because a proper match has been found in the attribute list
* entry above, the comparison can now be optimized. So it is
* worth re-implementing a simplified ntfs_attr_find() here.
*/
a = ctx->attr;
/*
* Use a manual loop so we can still use break and continue
* with the same meanings as above.
*/
do_next_attr_loop:
if ((u8*)a < (u8*)ctx->mrec || (u8*)a > (u8*)ctx->mrec +
le32_to_cpu(ctx->mrec->bytes_allocated))
break;
if (a->type == AT_END)
continue;
if (!a->length)
break;
if (al_entry->instance != a->instance)
goto do_next_attr;
/*
* If the type and/or the name are mismatched between the
* attribute list entry and the attribute record, there is
* corruption so we break and return error EIO.
*/
if (al_entry->type != a->type)
break;
if (!ntfs_are_names_equal((ntfschar*)((u8*)a +
le16_to_cpu(a->name_offset)), a->name_length,
al_name, al_name_len, CASE_SENSITIVE,
vol->upcase, vol->upcase_len))
break;
ctx->attr = a;
/*
* If no @val specified or @val specified and it matches, we
* have found it!
*/
if (!val || (!a->non_resident && le32_to_cpu(
a->data.resident.value_length) == val_len &&
!memcmp((u8*)a +
le16_to_cpu(a->data.resident.value_offset),
val, val_len))) {
ntfs_debug("Done, found.");
return 0;
}
do_next_attr:
/* Proceed to the next attribute in the current mft record. */
a = (ATTR_RECORD*)((u8*)a + le32_to_cpu(a->length));
goto do_next_attr_loop;
}
if (!err) {
ntfs_error(vol->sb, "Base inode 0x%lx contains corrupt "
"attribute list attribute.%s", base_ni->mft_no,
es);
err = -EIO;
}
if (ni != base_ni) {
if (ni)
unmap_extent_mft_record(ni);
ctx->ntfs_ino = base_ni;
ctx->mrec = ctx->base_mrec;
ctx->attr = ctx->base_attr;
}
if (err != -ENOMEM)
NVolSetErrors(vol);
return err;
not_found:
/*
* If we were looking for AT_END, we reset the search context @ctx and
* use ntfs_attr_find() to seek to the end of the base mft record.
*/
if (type == AT_END) {
ntfs_attr_reinit_search_ctx(ctx);
return ntfs_attr_find(AT_END, name, name_len, ic, val, val_len,
ctx);
}
/*
* The attribute was not found. Before we return, we want to ensure
* @ctx->mrec and @ctx->attr indicate the position at which the
* attribute should be inserted in the base mft record. Since we also
* want to preserve @ctx->al_entry we cannot reinitialize the search
* context using ntfs_attr_reinit_search_ctx() as this would set
* @ctx->al_entry to NULL. Thus we do the necessary bits manually (see
* ntfs_attr_init_search_ctx() below). Note, we _only_ preserve
* @ctx->al_entry as the remaining fields (base_*) are identical to
* their non base_ counterparts and we cannot set @ctx->base_attr
* correctly yet as we do not know what @ctx->attr will be set to by
* the call to ntfs_attr_find() below.
*/
if (ni != base_ni)
unmap_extent_mft_record(ni);
ctx->mrec = ctx->base_mrec;
ctx->attr = (ATTR_RECORD*)((u8*)ctx->mrec +
le16_to_cpu(ctx->mrec->attrs_offset));
ctx->is_first = TRUE;
ctx->ntfs_ino = base_ni;
ctx->base_ntfs_ino = NULL;
ctx->base_mrec = NULL;
ctx->base_attr = NULL;
/*
* In case there are multiple matches in the base mft record, need to
* keep enumerating until we get an attribute not found response (or
* another error), otherwise we would keep returning the same attribute
* over and over again and all programs using us for enumeration would
* lock up in a tight loop.
*/
do {
err = ntfs_attr_find(type, name, name_len, ic, val, val_len,
ctx);
} while (!err);
ntfs_debug("Done, not found.");
return err;
}
/**
* ntfs_attr_lookup - find an attribute in an ntfs inode
* @type: attribute type to find
* @name: attribute name to find (optional, i.e. NULL means don't care)
* @name_len: attribute name length (only needed if @name present)
* @ic: IGNORE_CASE or CASE_SENSITIVE (ignored if @name not present)
* @lowest_vcn: lowest vcn to find (optional, non-resident attributes only)
* @val: attribute value to find (optional, resident attributes only)
* @val_len: attribute value length
* @ctx: search context with mft record and attribute to search from
*
* Find an attribute in an ntfs inode. On first search @ctx->ntfs_ino must
* be the base mft record and @ctx must have been obtained from a call to
* ntfs_attr_get_search_ctx().
*
* This function transparently handles attribute lists and @ctx is used to
* continue searches where they were left off at.
*
* After finishing with the attribute/mft record you need to call
* ntfs_attr_put_search_ctx() to cleanup the search context (unmapping any
* mapped inodes, etc).
*
* Return 0 if the search was successful and -errno if not.
*
* When 0, @ctx->attr is the found attribute and it is in mft record
* @ctx->mrec. If an attribute list attribute is present, @ctx->al_entry is
* the attribute list entry of the found attribute.
*
* When -ENOENT, @ctx->attr is the attribute which collates just after the
* attribute being searched for, i.e. if one wants to add the attribute to the
* mft record this is the correct place to insert it into. If an attribute
* list attribute is present, @ctx->al_entry is the attribute list entry which
* collates just after the attribute list entry of the attribute being searched
* for, i.e. if one wants to add the attribute to the mft record this is the
* correct place to insert its attribute list entry into.
*
* When -errno != -ENOENT, an error occured during the lookup. @ctx->attr is
* then undefined and in particular you should not rely on it not changing.
*/
int ntfs_attr_lookup(const ATTR_TYPE type, const ntfschar *name,
const u32 name_len, const IGNORE_CASE_BOOL ic,
const VCN lowest_vcn, const u8 *val, const u32 val_len,
ntfs_attr_search_ctx *ctx)
{
ntfs_inode *base_ni;
ntfs_debug("Entering.");
if (ctx->base_ntfs_ino)
base_ni = ctx->base_ntfs_ino;
else
base_ni = ctx->ntfs_ino;
/* Sanity check, just for debugging really. */
BUG_ON(!base_ni);
if (!NInoAttrList(base_ni) || type == AT_ATTRIBUTE_LIST)
return ntfs_attr_find(type, name, name_len, ic, val, val_len,
ctx);
return ntfs_external_attr_find(type, name, name_len, ic, lowest_vcn,
val, val_len, ctx);
}
/**
* ntfs_attr_init_search_ctx - initialize an attribute search context
* @ctx: attribute search context to initialize
* @ni: ntfs inode with which to initialize the search context