/**
* runlist.c - NTFS runlist handling code. 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 "debug.h"
#include "dir.h"
#include "endian.h"
#include "malloc.h"
#include "ntfs.h"
/**
* ntfs_rl_mm - runlist memmove
*
* It is up to the caller to serialize access to the runlist @base.
*/
static inline void ntfs_rl_mm(runlist_element *base, int dst, int src,
int size)
{
if (likely((dst != src) && (size > 0)))
memmove(base + dst, base + src, size * sizeof(*base));
}
/**
* ntfs_rl_mc - runlist memory copy
*
* It is up to the caller to serialize access to the runlists @dstbase and
* @srcbase.
*/
static inline void ntfs_rl_mc(runlist_element *dstbase, int dst,
runlist_element *srcbase, int src, int size)
{
if (likely(size > 0))
memcpy(dstbase + dst, srcbase + src, size * sizeof(*dstbase));
}
/**
* ntfs_rl_realloc - Reallocate memory for runlists
* @rl: original runlist
* @old_size: number of runlist elements in the original runlist @rl
* @new_size: number of runlist elements we need space for
*
* As the runlists grow, more memory will be required. To prevent the
* kernel having to allocate and reallocate large numbers of small bits of
* memory, this function returns an entire page of memory.
*
* It is up to the caller to serialize access to the runlist @rl.
*
* N.B. If the new allocation doesn't require a different number of pages in
* memory, the function will return the original pointer.
*
* On success, return a pointer to the newly allocated, or recycled, memory.
* On error, return -errno. The following error codes are defined:
* -ENOMEM - Not enough memory to allocate runlist array.
* -EINVAL - Invalid parameters were passed in.
*/
static inline runlist_element *ntfs_rl_realloc(runlist_element *rl,
int old_size, int new_size)
{
runlist_element *new_rl;
old_size = PAGE_ALIGN(old_size * sizeof(*rl));
new_size = PAGE_ALIGN(new_size * sizeof(*rl));
if (old_size == new_size)
return rl;
new_rl = ntfs_malloc_nofs(new_size);
if (unlikely(!new_rl))
return ERR_PTR(-ENOMEM);
if (likely(rl != NULL)) {
if (unlikely(old_size > new_size))
old_size = new_size;
memcpy(new_rl, rl, old_size);
ntfs_free(rl);
}
return new_rl;
}
/**
* ntfs_rl_realloc_nofail - Reallocate memory for runlists
* @rl: original runlist
* @old_size: number of runlist elements in the original runlist @rl
* @new_size: number of runlist elements we need space for
*
* As the runlists grow, more memory will be required. To prevent the
* kernel having to allocate and reallocate large numbers of small bits of
* memory, this function returns an entire page of memory.
*
* This function guarantees that the allocation will succeed. It will sleep
* for as long as it takes to complete the allocation.
*
* It is up to the caller to serialize access to the runlist @rl.
*
* N.B. If the new allocation doesn't require a different number of pages in
* memory, the function will return the original pointer.
*
* On success, return a pointer to the newly allocated, or recycled, memory.
* On error, return -errno. The following error codes are defined:
* -ENOMEM - Not enough memory to allocate runlist array.
* -EINVAL - Invalid parameters were passed in.
*/
static inline runlist_element *ntfs_rl_realloc_nofail(runlist_element *rl,
int old_size, int new_size)
{
runlist_element *new_rl;
old_size = PAGE_ALIGN(old_size * sizeof(*rl));
new_size = PAGE_ALIGN(new_size * sizeof(*rl));
if (old_size == new_size)
return rl;
new_rl = ntfs_malloc_nofs_nofail(new_size);
BUG_ON(!new_rl);
if (likely(rl != NULL)) {
if (unlikely(old_size > new_size))
old_size = new_size;
memcpy(new_rl, rl, old_size);
ntfs_free(rl);
}
return new_rl;
}
/**
* ntfs_are_rl_mergeable - test if two runlists can be joined together
* @dst: original runlist
* @src: new runlist to test for mergeability with @dst
*
* Test if two runlists can be joined together. For this, their VCNs and LCNs
* must be adjacent.
*
* It is up to the caller to serialize access to the runlists @dst and @src.
*
* Return: TRUE Success, the runlists can be merged.
* FALSE Failure, the runlists cannot be merged.
*/
static inline BOOL ntfs_are_rl_mergeable(runlist_element *dst,
runlist_element *src)
{
BUG_ON(!dst);
BUG_ON(!src);
if ((dst->lcn < 0) || (src->lcn < 0)) { /* Are we merging holes? */
if (dst->lcn == LCN_HOLE && src->lcn == LCN_HOLE)
return TRUE;
return FALSE;
}
if ((dst->lcn + dst->length) != src->lcn) /* Are the runs contiguous? */
return FALSE;
if ((dst->vcn + dst->length) != src->vcn) /* Are the runs misaligned? */
return FALSE;
return TRUE;
}
/**
* __ntfs_rl_merge - merge two runlists without testing if they can be merged
* @dst: original, destination runlist
* @src: new runlist to merge with @dst
*
* Merge the two runlists, writing into the destination runlist @dst. The
* caller must make sure the runlists can be merged or this will corrupt the
* destination runlist.
*
* It is up to the caller to serialize access to the runlists @dst and @src.
*/
static inline void __ntfs_rl_merge(runlist_element *dst, runlist_element *src)
{
dst->length += src->length;
}
/**
* ntfs_rl_append - append a runlist after a given element
* @dst: original runlist to be worked on
* @dsize: number of elements in @dst (including end marker)
* @src: runlist to be inserted into @dst
* @ssize: number of elements in @src (excluding end marker)
* @loc: append the new runlist @src after this element in @dst
*
* Append the runlist @src after element @loc in @dst. Merge the right end of
* the new runlist, if necessary. Adjust the size of the hole before the
* appended runlist.
*
* It is up to the caller to serialize access to the runlists @dst and @src.
*
* On success, return a pointer to the new, combined, runlist. Note, both
* runlists @dst and @src are deallocated before returning so you cannot use
* the pointers for anything any more. (Strictly speaking the returned runlist
* may be the same as @dst but this is irrelevant.)
*
* On error, return -errno. Both runlists are left unmodified. The following
* error codes are defined:
* -ENOMEM - Not enough memory to allocate runlist array.
* -EINVAL - Invalid parameters were passed in.
*/
static inline runlist_element *ntfs_rl_append(runlist_element *dst,
int dsize, runlist_element *src, int ssize, int loc)
{
BOOL right;
int magic;
BUG_ON(!dst);
BUG_ON(!src);
/* First, check if the right hand end needs merging. */
right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1);
/* Space required: @dst size + @src size, less one if we merged. */
dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - right);
if (IS_ERR(dst))
return dst;
/*
* We are guaranteed to succeed from here so can start modifying the
* original runlists.
*/
/* First, merge the right hand end, if necessary. */
if (right)
__ntfs_rl_merge(src + ssize - 1, dst + loc + 1);
magic = loc + ssize;
/* Move the tail of @dst out of the way, then copy in @src. */
ntfs_rl_mm(dst, magic + 1, loc + 1 + right, dsize - loc - 1 - right);
ntfs_rl_mc(dst, loc + 1, src, 0, ssize);
/* Adjust the size of the preceding hole. */
dst[loc].length = dst[loc + 1].vcn - dst[loc].vcn;
/* We may have changed the length of the file, so fix the end marker */
if (dst[magic + 1].lcn == LCN_ENOENT)
dst[magic + 1].vcn = dst[magic].vcn + dst[magic].length;
return dst;
}
/**
* ntfs_rl_insert - insert a runlist into another
* @dst: original runlist to be worked on
* @dsize: number of elements in @dst (including end marker)
* @src: new runlist to be inserted
* @ssize: number of elements in @src (excluding end marker)
* @loc: insert the new runlist @src before this element in @dst
*
* Insert the runlist @src before element @loc in the runlist @dst. Merge the
* left end of the new runlist, if necessary. Adjust the size of the hole
* after the inserted runlist.
*
* It is up to the caller to serialize access to the runlists @dst and @src.
*
* On success, return a pointer to the new, combined, runlist. Note, both
* runlists @dst and @src are deallocated before returning so you cannot use
* the pointers for anything any more. (Strictly speaking the returned runlist
* may be the same as @dst but this is irrelevant.)
*
* On error, return -errno. Both runlists are left unmodified. The following
* error codes are defined:
* -ENOMEM - Not enough memory to allocate runlist array.
* -EINVAL - Invalid parameters were passed in.
*/
static inline runlist_element *ntfs_rl_insert(runlist_element *dst,
int dsize, runlist_element *src, int ssize, int loc)
{
BOOL left = FALSE;
BOOL disc = FALSE; /* Discontinuity */
BOOL hole = FALSE; /* Following a hole */
int magic;
BUG_ON(!dst);
BUG_ON(!src);
/* disc => Discontinuity between the end of @dst and the start of @src.
* This means we might need to insert a hole.
* hole => @dst ends with a hole or an unmapped region which we can
* extend to match the discontinuity. */
if (loc == 0)
disc = (src[0].vcn > 0);
else {
s64 merged_length;
left = ntfs_are_rl_mergeable(dst + loc - 1, src);
merged_length = dst[loc - 1].length;
if (left)
merged_length += src->length;
disc = (src[0].vcn > dst[loc - 1].vcn + merged_length);
if (disc)
hole = (dst[loc - 1].lcn == LCN_HOLE);
}
/* Space required: @dst size + @src size, less one if we merged, plus
* one if there was a discontinuity, less one for a trailing hole. */
dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left + disc - hole);
if (IS_ERR(dst))
return dst;
/*
* We are guaranteed to succeed from here so can start modifying the
* original runlist.
*/
if (left)
__ntfs_rl_merge(dst + loc - 1, src);
magic = loc + ssize - left + disc - hole;
/* Move the tail of @dst out of the way, then copy in @src. */
ntfs_rl_mm(dst, magic, loc, dsize - loc);
ntfs_rl_mc(dst, loc + disc - hole, src, left, ssize - left);
/* Adjust the VCN of the last run ... */
if (dst[magic].lcn <= LCN_HOLE)
dst[magic].vcn = dst[magic - 1].vcn + dst[magic - 1].length;
/* ... and the length. */
if (dst[magic].lcn == LCN_HOLE || dst[magic].lcn == LCN_RL_NOT_MAPPED)
dst[magic].length = dst[magic + 1].vcn - dst[magic].vcn;
/* Writing beyond the end of the file and there's a discontinuity. */
if (disc) {
if (hole)
dst[loc - 1].length = dst[loc].vcn - dst[loc - 1].vcn;
else {
if (loc > 0) {
dst[loc].vcn = dst[loc - 1].vcn +
dst[loc - 1].length;
dst[loc].length = dst[loc + 1].vcn -
dst[loc].vcn;
} else {
dst[loc].vcn = 0;
dst[loc].length = dst[loc + 1].vcn;
}
dst[loc].lcn = LCN_RL_NOT_MAPPED;
}
magic += hole;
if (dst[magic].lcn == LCN_ENOENT)
dst[magic].vcn = dst[magic - 1].vcn +
dst[magic - 1].length;
}
return dst;
}
/**
* ntfs_rl_replace - overwrite a runlist element with another runlist
* @dst: original runlist to be worked on
* @dsize: number of elements in @dst (including end marker)
* @src: new runlist to be inserted
* @ssize: number of elements in @src (excluding end marker)
* @loc: index in runlist @dst to overwrite with @src
*
* Replace the runlist element @dst at @loc with @src. Merge the left and
* right ends of the inserted runlist, if necessary.
*
* It is up to the caller to serialize access to the runlists @dst and @src.
*
* On success, return a pointer to the new, combined, runlist. Note, both
* runlists @dst and @src are deallocated before returning so you cannot use
* the pointers for anything any more. (Strictly speaking the returned runlist
* may be the same as @dst but this is irrelevant.)
*
* On error, return -errno. Both runlists are left unmodified. The following
* error codes are defined:
* -ENOMEM - Not enough memory to allocate runlist array.
* -EINVAL - Invalid parameters were passed in.
*/
static inline runlist_element *ntfs_rl_replace(runlist_element *dst,
int dsize, runlist_element *src, int ssize, int loc)
{
BOOL left = FALSE;
BOOL right;
int magic;
BUG_ON(!dst);
BUG_ON(!src);
/* First, merge the left and right ends, if necessary. */
right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1);
if (loc > 0)
left = ntfs_are_rl_mergeable(dst + loc - 1, src);
/* Allocate some space. We'll need less if the left, right, or both
* ends were merged. */
dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left - right);
if (IS_ERR(dst))
return dst;
/*
* We are guaranteed to succeed from here so can start modifying the
* original runlists.
*/
if (right)
__ntfs_rl_merge(src + ssize - 1, dst + loc + 1);
if (left)
__ntfs_rl_merge(dst + loc - 1, src);
/* FIXME: What does this mean? (AIA) */
magic = loc + ssize - left;
/* Move the tail of @dst out of the way, then copy in @src. */
ntfs_rl_mm(dst, magic, loc + right + 1, dsize - loc - right - 1);
ntfs_rl_mc(dst, loc, src, left, ssize - left);
/* We may have changed the length of the file, so fix the end marker */
if (dst[magic].lcn == LCN_ENOENT)
dst[magic].vcn = dst[magic - 1].vcn + dst[magic - 1].length;
return dst;
}
/**
* ntfs_rl_split - insert a runlist into the centre of a hole
* @dst: original runlist to be worked on
* @dsize: number of elements in @dst (including end marker)
* @src: new runlist to be inserted
* @ssize: number of elements in @src (excluding end marker)
* @loc: index in runlist @dst at which to split and insert @src
*
* Split the runlist @dst at @loc into two and insert @new in between the two
* fragments. No merging of runlists is necessary. Adjust the size of the
* holes either side.
*
* It is up to the caller to serialize access to the runlists @dst and @src.
*
* On success, return a pointer to the new, combined, runlist. Note, both
* runlists @dst and @src are deallocated before returning so you cannot use
* the pointers for anything any more. (Strictly speaking the returned runlist
* may be the same as @dst but this is irrelevant.)
*
* On error, return -errno. Both runlists are left unmodified. The following
* error codes are defined:
* -ENOMEM - Not enough memory to allocate runlist array.
* -EINVAL - Invalid parameters were passed in.
*/
static inline runlist_element *ntfs_rl_split(runlist_element *dst, int dsize,
runlist_element *src, int ssize, int loc)
{
BUG_ON(!dst);
BUG_ON(!src);
/* Space required: @dst size + @src size + one new hole. */
dst = ntfs_rl_realloc(dst, dsize, dsize + ssize + 1);
if (IS_ERR(dst))
return dst;
/*
* We are guaranteed to succeed from here so can start modifying the
* original runlists.
*/
/* Move the tail of @dst out of the way, then copy in @src. */
ntfs_rl_mm(dst, loc + 1 + ssize, loc, dsize - loc);
ntfs_rl_mc(dst, loc + 1, src, 0, ssize);
/* Adjust the size of the holes either size of @src. */
dst[loc].length = dst[loc+1].vcn - dst[loc].vcn;
dst[loc+ssize+1].vcn = dst[loc+ssize].vcn + dst[loc+ssize].length;
dst[loc+ssize+1].length = dst[loc+ssize+2].vcn - dst[loc+ssize+1].vcn;
return dst;
}
/**
* ntfs_runlists_merge - merge two runlists into one
* @drl: original runlist to be worked on
* @srl: new runlist to be merged into @drl
*
* First we sanity check the two runlists @srl and @drl to make sure that they
* are sensible and can be merged. The runlist @srl must be either after the
* runlist @drl or completely within a hole (or unmapped region) in @drl.
*
* It is up to the caller to serialize access to the runlists @drl and @srl.
*
* Merging of runlists is necessary in two cases:
* 1. When attribute lists are used and a further extent is being mapped.
* 2. When new clusters are allocated to fill a hole or extend a file.
*
* There are four possible ways @srl can be merged. It can:
* - be inserted at the beginning of a hole,
* - split the hole in two and be inserted between the two fragments,
* - be appended at the end of a hole, or it can
* - replace the whole hole.
* It can also be appended to the end of the runlist, which is just a variant
* of the insert case.
*
* On success, return a pointer to the new, combined, runlist. Note, both
* runlists @drl and @srl are deallocated before returning so you cannot use
* the pointers for anything any more. (Strictly speaking the returned runlist
* may be the same as @dst but this is irrelevant.)
*
* On error, return -errno. Both runlists are left unmodified. The following
* error codes are defined:
* -ENOMEM - Not enough memory to allocate runlist array.
* -EINVAL - Invalid parameters were passed in.
* -ERANGE - The runlists overlap and cannot be merged.
*/
runlist_element *ntfs_runlists_merge(runlist_element *drl,
runlist_element *srl)
{
int di, si; /* Current index into @[ds]rl. */
int sstart; /* First index with lcn > LCN_RL_NOT_MAPPED. */
int dins; /* Index into @drl at which to insert @srl. */
int dend, send; /* Last index into @[ds]rl. */
int dfinal, sfinal; /* The last index into @[ds]rl with
lcn >= LCN_HOLE. */
int marker = 0;
VCN marker_vcn = 0;
#ifdef DEBUG
ntfs_debug("dst:");
ntfs_debug_dump_runlist(drl);
ntfs_debug("src:");
ntfs_debug_dump_runlist(srl);
#endif
/* Check for silly calling... */
if (unlikely(!srl))
return drl;
if (IS_ERR(srl) || IS_ERR(drl))
return ERR_PTR(-EINVAL);
/* Check for the case where the first mapping is being done now. */
if (unlikely(!drl)) {
drl = srl;
/* Complete the source runlist if necessary. */
if (unlikely(drl[0].vcn)) {
/* Scan to the end of the source runlist. */
for (dend = 0; likely(drl[dend].length); dend++)
;
dend++;
drl = ntfs_rl_realloc(drl, dend, dend + 1);
if (IS_ERR(drl))
return drl;
/* Insert start element at the front of the runlist. */
ntfs_rl_mm(drl, 1, 0, dend);
drl[0].vcn = 0;
drl[0].lcn = LCN_RL_NOT_MAPPED;
drl[0].length = drl[1].vcn;
}
goto finished;
}
si = di = 0;
/* Skip any unmapped start element(s) in the source runlist. */
while (srl[si].length && srl[si].lcn < LCN_HOLE)
si++;
/* Can't have an entirely unmapped source runlist. */
BUG_ON(!srl[si].length);
/* Record the starting points. */
sstart = si;
/*
* Skip forward in @drl until we reach the position where @srl needs to
* be inserted. If we reach the end of @drl, @srl just needs to be
* appended to @drl.
*/
for (; drl[di].length; di++) {
if (drl[di].vcn + drl[di].length > srl[sstart].vcn)
break;
}
dins = di;
/* Sanity check for illegal overlaps. */
if ((drl[di].vcn == srl[si].vcn) && (drl[di].lcn >= 0) &&
(srl[si].lcn >= 0)) {
ntfs_error(NULL, "Run lists overlap. Cannot merge!");
return ERR_PTR(-ERANGE);
}
/* Scan to the end of both runlists in order to know their sizes. */
for (send = si; srl[send].length; send++)
;
for (dend = di; drl[dend].length; dend++)
;
if (srl[send].lcn == LCN_ENOENT)
marker_vcn = srl[marker = send].vcn;
/* Scan to the last element with lcn >= LCN_HOLE. */
for (sfinal = send; sfinal >= 0 && srl[sfinal].lcn < LCN_HOLE; sfinal--)
;
for (dfinal = dend; dfinal >= 0 && drl[dfinal].lcn < LCN_HOLE; dfinal--)
;
{
BOOL start;
BOOL finish;
int ds = dend + 1; /* Number of elements in drl & srl */
int ss = sfinal - sstart + 1;
start = ((drl[dins].lcn < LCN_RL_NOT_MAPPED) || /* End of file */
(drl[dins].vcn == srl[sstart].vcn)); /* Start of hole */
finish = ((drl[dins].lcn >= LCN_RL_NOT_MAPPED) && /* End of file */
((drl[dins].vcn + drl[dins].length) <= /* End of hole */
(srl[send - 1].vcn + srl[send - 1].length)));
/* Or we will lose an end marker. */
if (finish && !drl[dins].length)
ss++;
if (marker && (drl[dins].vcn + drl[dins].length > srl[send - 1].vcn))
finish = FALSE;
#if 0
ntfs_debug("dfinal = %i, dend = %i", dfinal, dend);
ntfs_debug("sstart = %i, sfinal = %i, send = %i", sstart, sfinal, send);
ntfs_debug("start = %i, finish = %i", start, finish);
ntfs_debug("ds = %i, ss = %i, dins = %i", ds, ss, dins);
#endif
if (start) {
if (finish)
drl = ntfs_rl_replace(drl, ds, srl + sstart, ss, dins);
else
drl = ntfs_rl_insert(drl, ds, srl + sstart, ss, dins);
} else {
if (finish)
drl = ntfs_rl_append(drl, ds, srl + sstart, ss, dins);
else
drl = ntfs_rl_split(drl, ds, srl + sstart, ss, dins);
}
if (IS_ERR(drl)) {
ntfs_error(NULL, "Merge failed.");
return drl;
}
ntfs_free(srl);
if (marker) {
ntfs_debug("Triggering marker code.");
for (ds = dend; drl[ds].length; ds++)
;
/* We only need to care if @srl ended after @drl. */
if (drl[ds].vcn <= marker_vcn) {
int slots = 0;
if (drl[ds].vcn == marker_vcn) {
ntfs_debug("Old marker = 0x%llx, replacing "
"with LCN_ENOENT.",
(unsigned long long)
drl[ds].lcn);
drl[ds].lcn = LCN_ENOENT;
goto finished;
}
/*
* We need to create an unmapped runlist element in
* @drl or extend an existing one before adding the
* ENOENT terminator.
*/
if (drl[ds].lcn == LCN_ENOENT) {
ds--;
slots = 1;
}
if (drl[ds].lcn != LCN_RL_NOT_MAPPED) {
/* Add an unmapped runlist element. */
if (!slots) {
drl = ntfs_rl_realloc_nofail(drl, ds,
ds + 2);
slots = 2;
}
ds++;
/* Need to set vcn if it isn't set already. */
if (slots != 1)
drl[ds].vcn = drl[ds - 1].vcn +
drl[ds - 1].length;
drl[ds].lcn = LCN_RL_NOT_MAPPED;
/* We now used up a slot. */
slots--;
}
drl[ds].length = marker_vcn - drl[ds].vcn;
/* Finally add the ENOENT terminator. */
ds++;
if (!slots)
drl = ntfs_rl_realloc_nofail(drl, ds, ds + 1);
drl[ds].vcn = marker_vcn;
drl[ds].lcn = LCN_ENOENT;
drl[ds].length = (s64)0;
}
}
}
finished:
/* The merge was completed successfully. */
ntfs_debug("Merged runlist:");
ntfs_debug_dump_runlist(drl);
return drl;
}
/**
* ntfs_mapping_pairs_decompress - convert mapping pairs array to runlist
* @vol: ntfs volume on which the attribute resides
* @attr: attribute record whose mapping pairs array to decompress
* @old_rl: optional runlist in which to insert @attr's runlist
*
* It is up to the caller to serialize access to the runlist @old_rl.
*
* Decompress the attribute @attr's mapping pairs array into a runlist. On
* success, return the decompressed runlist.
*
* If @old_rl is not NULL, decompressed runlist is inserted into the
* appropriate place in @old_rl and the resultant, combined runlist is
* returned. The original @old_rl is deallocated.
*
* On error, return -errno. @old_rl is left unmodified in that case.
*
* The following error codes are defined:
* -ENOMEM - Not enough memory to allocate runlist array.
* -EIO - Corrupt runlist.
* -EINVAL - Invalid parameters were passed in.
* -ERANGE - The two runlists overlap.
*
* FIXME: For now we take the conceptionally simplest approach of creating the
* new runlist disregarding the already existing one and then splicing the
* two into one, if that is possible (we check for overlap and discard the new
* runlist if overlap present before returning ERR_PTR(-ERANGE)).
*/
runlist_element *ntfs_mapping_pairs_decompress(const ntfs_volume *vol,
const ATTR_RECORD *attr, runlist_element *old_rl)
{
VCN vcn; /* Current vcn. */
LCN lcn; /* Current lcn. */
s64 deltaxcn; /* Change in [vl]cn. */
runlist_element *rl; /* The output runlist. */
u8 *buf; /* Current position in mapping pairs array. */
u8 *attr_end; /* End of attribute. */
int rlsize; /* Size of runlist buffer. */
u16 rlpos; /* Current runlist position in units of
runlist_elements. */
u8 b; /* Current byte offset in buf. */
#ifdef DEBUG
/* Make sure attr exists and is non-resident. */
if (!attr || !attr->non_resident || sle64_to_cpu(
attr->data.non_resident.lowest_vcn) < (VCN)0) {
ntfs_error(vol->sb, "Invalid arguments.");
return ERR_PTR(-EINVAL);
}
#endif
/* Start at vcn = lowest_vcn and lcn 0. */
vcn = sle64_to_cpu(attr->data.non_resident.lowest_vcn);
lcn = 0;
/* Get start of the mapping pairs array. */
buf = (u8*)attr + le16_to_cpu(
attr->data.non_resident.mapping_pairs_offset);
attr_end = (u8*)attr + le32_to_cpu(attr->length);
if (unlikely(buf < (u8*)attr || buf > attr_end)) {
ntfs_error(vol->sb, "Corrupt attribute.");
return ERR_PTR(-EIO);
}
/* If the mapping pairs array is valid but empty, nothing to do. */
if (!vcn && !*buf)
return old_rl;
/* Current position in runlist array. */
rlpos = 0;
/* Allocate first page and set current runlist size to one page. */
rl = ntfs_malloc_nofs(rlsize = PAGE_SIZE);
if (unlikely(!rl))
return ERR_PTR(-ENOMEM);
/* Insert unmapped starting element if necessary. */
if (vcn) {
rl->vcn = 0;
rl->lcn = LCN_RL_NOT_MAPPED;
rl->length = vcn;
rlpos++;
}
while (buf < attr_end && *buf) {
/*
* Allocate more memory if needed, including space for the
* not-mapped and terminator elements. ntfs_malloc_nofs()
* operates on whole pages only.
*/
if (((rlpos + 3) * sizeof(*old_rl)) > rlsize) {
runlist_element *rl2;
rl2 = ntfs_malloc_nofs(rlsize + (int)PAGE_SIZE);
if (unlikely(!rl2)) {
ntfs_free(rl);
return ERR_PTR(-ENOMEM);
}
memcpy(rl2, rl, rlsize);
ntfs_free(rl);
rl = rl2;
rlsize += PAGE_SIZE;
}
/* Enter the current vcn into the current runlist element. */
rl[rlpos].vcn = vcn;
/*
* Get the change in vcn, i.e. the run length in clusters.
* Doing it this way ensures that we signextend negative values.
* A negative run length doesn't make any sense, but hey, I
* didn't make up the NTFS specs and Windows NT4 treats the run
* length as a signed value so that's how it is...
*/
b = *buf & 0xf;
if (b) {
if (unlikely(buf + b > attr_end))
goto io_error;
for (deltaxcn = (s8)buf[b--]; b; b--)
deltaxcn = (deltaxcn << 8) + buf[b];
} else { /* The length entry is compulsory. */
ntfs_error(vol->sb, "Missing length entry in mapping "
"pairs array.");
deltaxcn = (s64)-1;
}
/*
* Assume a negative length to indicate data corruption and
* hence clean-up and return NULL.
*/
if (unlikely(deltaxcn < 0)) {
ntfs_error(vol->sb, "Invalid length in mapping pairs "
"array.");
goto err_out;
}
/*
* Enter the current run length into the current runlist
* element.
*/
rl[rlpos].length = deltaxcn;
/* Increment the current vcn by the current run length. */
vcn += deltaxcn;
/*
* There might be no lcn change at all, as is the case for
* sparse clusters on NTFS 3.0+, in which case we set the lcn
* to LCN_HOLE.
*/
if (!(*buf & 0xf0))
rl[rlpos].lcn = LCN_HOLE;
else {
/* Get the lcn change which really can be negative. */
u8 b2 = *buf & 0xf;
b = b2 + ((*buf >> 4) & 0xf);
if (buf + b > attr_end)
goto io_error;
for (deltaxcn = (s8)buf[b--]; b > b2; b--)
deltaxcn = (deltaxcn << 8) + buf[b];
/* Change the current lcn to its new value. */
lcn += deltaxcn;
#ifdef DEBUG
/*
* On NTFS 1.2-, apparently can have lcn == -1 to
* indicate a hole. But we haven't verified ourselves
* whether it is really the lcn or the deltaxcn that is
* -1. So if either is found give us a message so we
* can investigate it further!
*/
if (vol->major_ver < 3) {
if (unlikely(deltaxcn == (LCN)-1))
ntfs_error(vol->sb, "lcn delta == -1");
if (unlikely(lcn == (LCN)-1))
ntfs_error(vol->sb, "lcn == -1");
}
#endif
/* Check lcn is not below -1. */
if (unlikely(lcn < (LCN)-1)) {
ntfs_error(vol->sb, "Invalid LCN < -1 in "
"mapping pairs array.");
goto err_out;
}
/* Enter the current lcn into the runlist element. */
rl[rlpos].lcn = lcn;
}
/* Get to the next runlist element. */
rlpos++;
/* Increment the buffer position to the next mapping pair. */
buf += (*buf & 0xf) + ((*buf >> 4) & 0xf) + 1;
}
if (unlikely(buf >= attr_end))
goto io_error;
/*
* If there is a highest_vcn specified, it must be equal to the final
* vcn in the runlist - 1, or something has gone badly wrong.
*/
deltaxcn = sle64_to_cpu(attr->data.non_resident.highest_vcn);
if (unlikely(deltaxcn && vcn - 1 != deltaxcn)) {
mpa_err:
ntfs_error(vol->sb, "Corrupt mapping pairs array in "
"non-resident attribute.");
goto err_out;
}
/* Setup not mapped runlist element if this is the base extent. */
if (!attr->data.non_resident.lowest_vcn) {
VCN max_cluster;
max_cluster = ((sle64_to_cpu(
attr->data.non_resident.allocated_size) +
vol->cluster_size - 1) >>
vol->cluster_size_bits) - 1;
/*
* A highest_vcn of zero means this is a single extent
* attribute so simply terminate the runlist with LCN_ENOENT).
*/
if (deltaxcn) {
/*
* If there is a difference between the highest_vcn and
* the highest cluster, the runlist is either corrupt
* or, more likely, there are more extents following
* this one.
*/
if (deltaxcn < max_cluster) {
ntfs_debug("More extents to follow; deltaxcn "
"= 0x%llx, max_cluster = "
"0x%llx",
(unsigned long long)deltaxcn,
(unsigned long long)
max_cluster);
rl[rlpos].vcn = vcn;
vcn += rl[rlpos].length = max_cluster -
deltaxcn;
rl[rlpos].lcn = LCN_RL_NOT_MAPPED;
rlpos++;
} else if (unlikely(deltaxcn > max_cluster)) {
ntfs_error(vol->sb, "Corrupt attribute. "
"deltaxcn = 0x%llx, "
"max_cluster = 0x%llx",
(unsigned long long)deltaxcn,
(unsigned long long)
max_cluster);
goto mpa_err;
}
}
rl[rlpos].lcn = LCN_ENOENT;
} else /* Not the base extent. There may be more extents to follow. */
rl[rlpos].lcn = LCN_RL_NOT_MAPPED;
/* Setup terminating runlist element. */
rl[rlpos].vcn = vcn;
rl[rlpos].length = (s64)0;
/* If no existing runlist was specified, we are done. */
if (!old_rl) {
ntfs_debug("Mapping pairs array successfully decompressed:");
ntfs_debug_dump_runlist(rl);
return rl;
}
/* Now combine the new and old runlists checking for overlaps. */
old_rl = ntfs_runlists_merge(old_rl, rl);
if (likely(!IS_ERR(old_rl)))
return old_rl;
ntfs_free(rl);
ntfs_error(vol->sb, "Failed to merge runlists.");
return old_rl;
io_error:
ntfs_error(vol->sb, "Corrupt attribute.");
err_out:
ntfs_free(rl);
return ERR_PTR(-EIO);
}
/**
* ntfs_rl_vcn_to_lcn - convert a vcn into a lcn given a runlist
* @rl: runlist to use for conversion
* @vcn: vcn to convert
*
* Convert the virtual cluster number @vcn of an attribute into a logical
* cluster number (lcn) of a device using the runlist @rl to map vcns to their
* corresponding lcns.
*
* It is up to the caller to serialize access to the runlist @rl.
*
* 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_RL_NOT_MAPPED This is part of the runlist which has not been
* inserted into the runlist yet.
* LCN_ENOENT There is no such vcn in the attribute.
*
* Locking: - The caller must have locked the runlist (for reading or writing).
* - This function does not touch the lock, nor does it modify the
* runlist.
*/
LCN ntfs_rl_vcn_to_lcn(const runlist_element *rl, const VCN vcn)
{
int i;
BUG_ON(vcn < 0);
/*
* If rl is NULL, assume that we have found an unmapped runlist. The
* caller can then attempt to map it and fail appropriately if
* necessary.
*/
if (unlikely(!rl))
return LCN_RL_NOT_MAPPED;
/* Catch out of lower bounds vcn. */
if (unlikely(vcn < rl[0].vcn))
return LCN_ENOENT;
for (i = 0; likely(rl[i].length); i++) {
if (unlikely(vcn < rl[i+1].vcn)) {
if (likely(rl[i].lcn >= (LCN)0))
return rl[i].lcn + (vcn - rl[i].vcn);
return rl[i].lcn;
}
}
/*
* The terminator element is setup to the correct value, i.e. one of
* LCN_HOLE, LCN_RL_NOT_MAPPED, or LCN_ENOENT.
*/
if (likely(rl[i].lcn < (LCN)0))
return rl[i].lcn;
/* Just in case... We could replace this with BUG() some day. */
return LCN_ENOENT;
}
#ifdef NTFS_RW
/**
* ntfs_rl_find_vcn_nolock - find a vcn in a runlist
* @rl: runlist to search
* @vcn: vcn to find
*
* Find the virtual cluster number @vcn in the runlist @rl and return the
* address of the runlist element containing the @vcn on success.
*
* Return NULL if @rl is NULL or @vcn is in an unmapped part/out of bounds of
* the runlist.
*
* Locking: The runlist must be locked on entry.
*/
runlist_element *ntfs_rl_find_vcn_nolock(runlist_element *rl, const VCN vcn)
{
BUG_ON(vcn < 0);
if (unlikely(!rl || vcn < rl[0].vcn))
return NULL;
while (likely(rl->length)) {
if (unlikely(vcn < rl[1].vcn)) {
if (likely(rl->lcn >= LCN_HOLE))
return rl;
return NULL;
}
rl++;
}
if (likely(rl->lcn == LCN_ENOENT))
return rl;
return NULL;
}
/**
* ntfs_get_nr_significant_bytes - get number of bytes needed to store a number
* @n: number for which to get the number of bytes for
*
* Return the number of bytes required to store @n unambiguously as
* a signed number.
*
* This is used in the context of the mapping pairs array to determine how
* many bytes will be needed in the array to store a given logical cluster
* number (lcn) or a specific run length.
*
* Return the number of bytes written. This function cannot fail.
*/
static inline int ntfs_get_nr_significant_bytes(const s64 n)
{
s64 l = n;
int i;
s8 j;
i = 0;
do {
l >>= 8;
i++;
} while (l != 0 && l != -1);
j = (n >> 8 * (i - 1)) & 0xff;
/* If the sign bit is wrong, we need an extra byte. */
if ((n < 0 && j >= 0) || (n > 0 && j < 0))
i++;
return i;
}
/**
* ntfs_get_size_for_mapping_pairs - get bytes needed for mapping pairs array
* @vol: ntfs volume (needed for the ntfs version)
* @rl: locked runlist to determine the size of the mapping pairs of
* @first_vcn: first vcn which to include in the mapping pairs array
* @last_vcn: last vcn which to include in the mapping pairs array
*
* Walk the locked runlist @rl and calculate the size in bytes of the mapping
* pairs array corresponding to the runlist @rl, starting at vcn @first_vcn and
* finishing with vcn @last_vcn.
*
* A @last_vcn of -1 means end of runlist and in that case the size of the
* mapping pairs array corresponding to the runlist starting at vcn @first_vcn
* and finishing at the end of the runlist is determined.
*
* This for example allows us to allocate a buffer of the right size when
* building the mapping pairs array.
*
* If @rl is NULL, just return 1 (for the single terminator byte).
*
* Return the calculated size in bytes on success. On error, return -errno.
* The following error codes are defined:
* -EINVAL - Run list contains unmapped elements. Make sure to only pass
* fully mapped runlists to this function.
* -EIO - The runlist is corrupt.
*
* Locking: @rl must be locked on entry (either for reading or writing), it
* remains locked throughout, and is left locked upon return.
*/
int ntfs_get_size_for_mapping_pairs(const ntfs_volume *vol,
const runlist_element *rl, const VCN first_vcn,
const VCN last_vcn)
{
LCN prev_lcn;
int rls;
BOOL the_end = FALSE;
BUG_ON(first_vcn < 0);
BUG_ON(last_vcn < -1);
BUG_ON(last_vcn >= 0 && first_vcn > last_vcn);
if (!rl) {
BUG_ON(first_vcn);
BUG_ON(last_vcn > 0);
return 1;
}
/* Skip to runlist element containing @first_vcn. */
while (rl->length && first_vcn >= rl[1].vcn)
rl++;
if (unlikely((!rl->length && first_vcn > rl->vcn) ||
first_vcn < rl->vcn))
return -EINVAL;
prev_lcn = 0;
/* Always need the termining zero byte. */
rls = 1;
/* Do the first partial run if present. */
if (first_vcn > rl->vcn) {
s64 delta, length = rl->length;
/* We know rl->length != 0 already. */
if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
goto err_out;
/*
* If @stop_vcn is given and finishes inside this run, cap the
* run length.
*/
if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
s64 s1 = last_vcn + 1;
if (unlikely(rl[1].vcn > s1))
length = s1 - rl->vcn;
the_end = TRUE;
}
delta = first_vcn - rl->vcn;
/* Header byte + length. */
rls += 1 + ntfs_get_nr_significant_bytes(length - delta);
/*
* If the logical cluster number (lcn) denotes a hole and we
* are on NTFS 3.0+, we don't store it at all, i.e. we need
* zero space. On earlier NTFS versions we just store the lcn.
* Note: this assumes that on NTFS 1.2-, holes are stored with
* an lcn of -1 and not a delta_lcn of -1 (unless both are -1).
*/
if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
prev_lcn = rl->lcn;
if (likely(rl->lcn >= 0))
prev_lcn += delta;
/* Change in lcn. */
rls += ntfs_get_nr_significant_bytes(prev_lcn);
}
/* Go to next runlist element. */
rl++;
}
/* Do the full runs. */
for (; rl->length && !the_end; rl++) {
s64 length = rl->length;
if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
goto err_out;
/*
* If @stop_vcn is given and finishes inside this run, cap the
* run length.
*/
if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
s64 s1 = last_vcn + 1;
if (unlikely(rl[1].vcn > s1))
length = s1 - rl->vcn;
the_end = TRUE;
}
/* Header byte + length. */
rls += 1 + ntfs_get_nr_significant_bytes(length);
/*
* If the logical cluster number (lcn) denotes a hole and we
* are on NTFS 3.0+, we don't store it at all, i.e. we need
* zero space. On earlier NTFS versions we just store the lcn.
* Note: this assumes that on NTFS 1.2-, holes are stored with
* an lcn of -1 and not a delta_lcn of -1 (unless both are -1).
*/
if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
/* Change in lcn. */
rls += ntfs_get_nr_significant_bytes(rl->lcn -
prev_lcn);
prev_lcn = rl->lcn;
}
}
return rls;
err_out:
if (rl->lcn == LCN_RL_NOT_MAPPED)
rls = -EINVAL;
else
rls = -EIO;
return rls;
}
/**
* ntfs_write_significant_bytes - write the significant bytes of a number
* @dst: destination buffer to write to
* @dst_max: pointer to last byte of destination buffer for bounds checking
* @n: number whose significant bytes to write
*
* Store in @dst, the minimum bytes of the number @n which are required to
* identify @n unambiguously as a signed number, taking care not to exceed
* @dest_max, the maximum position within @dst to which we are allowed to
* write.
*
* This is used when building the mapping pairs array of a runlist to compress
* a given logical cluster number (lcn) or a specific run length to the minumum
* size possible.
*
* Return the number of bytes written on success. On error, i.e. the
* destination buffer @dst is too small, return -ENOSPC.
*/
static inline int ntfs_write_significant_bytes(s8 *dst, const s8 *dst_max,
const s64 n)
{
s64 l = n;
int i;
s8 j;
i = 0;
do {
if (unlikely(dst > dst_max))
goto err_out;
*dst++ = l & 0xffll;
l >>= 8;
i++;
} while (l != 0 && l != -1);
j = (n >> 8 * (i - 1)) & 0xff;
/* If the sign bit is wrong, we need an extra byte. */
if (n < 0 && j >= 0) {
if (unlikely(dst > dst_max))
goto err_out;
i++;
*dst = (s8)-1;
} else if (n > 0 && j < 0) {
if (unlikely(dst > dst_max))
goto err_out;
i++;
*dst = (s8)0;
}
return i;
err_out:
return -ENOSPC;
}
/**
* ntfs_mapping_pairs_build - build the mapping pairs array from a runlist
* @vol: ntfs volume (needed for the ntfs version)
* @dst: destination buffer to which to write the mapping pairs array
* @dst_len: size of destination buffer @dst in bytes
* @rl: locked runlist for which to build the mapping pairs array
* @first_vcn: first vcn which to include in the mapping pairs array
* @last_vcn: last vcn which to include in the mapping pairs array
* @stop_vcn: first vcn outside destination buffer on success or -ENOSPC
*
* Create the mapping pairs array from the locked runlist @rl, starting at vcn
* @first_vcn and finishing with vcn @last_vcn and save the array in @dst.
* @dst_len is the size of @dst in bytes and it should be at least equal to the
* value obtained by calling ntfs_get_size_for_mapping_pairs().
*
* A @last_vcn of -1 means end of runlist and in that case the mapping pairs
* array corresponding to the runlist starting at vcn @first_vcn and finishing
* at the end of the runlist is created.
*
* If @rl is NULL, just write a single terminator byte to @dst.
*
* On success or -ENOSPC error, if @stop_vcn is not NULL, *@stop_vcn is set to
* the first vcn outside the destination buffer. Note that on error, @dst has
* been filled with all the mapping pairs that will fit, thus it can be treated
* as partial success, in that a new attribute extent needs to be created or
* the next extent has to be used and the mapping pairs build has to be
* continued with @first_vcn set to *@stop_vcn.
*
* Return 0 on success and -errno on error. The following error codes are
* defined:
* -EINVAL - Run list contains unmapped elements. Make sure to only pass
* fully mapped runlists to this function.
* -EIO - The runlist is corrupt.
* -ENOSPC - The destination buffer is too small.
*
* Locking: @rl must be locked on entry (either for reading or writing), it
* remains locked throughout, and is left locked upon return.
*/
int ntfs_mapping_pairs_build(const ntfs_volume *vol, s8 *dst,
const int dst_len, const runlist_element *rl,
const VCN first_vcn, const VCN last_vcn, VCN *const stop_vcn)
{
LCN prev_lcn;
s8 *dst_max, *dst_next;
int err = -ENOSPC;
BOOL the_end = FALSE;
s8 len_len, lcn_len;
BUG_ON(first_vcn < 0);
BUG_ON(last_vcn < -1);
BUG_ON(last_vcn >= 0 && first_vcn > last_vcn);
BUG_ON(dst_len < 1);
if (!rl) {
BUG_ON(first_vcn);
BUG_ON(last_vcn > 0);
if (stop_vcn)
*stop_vcn = 0;
/* Terminator byte. */
*dst = 0;
return 0;
}
/* Skip to runlist element containing @first_vcn. */
while (rl->length && first_vcn >= rl[1].vcn)
rl++;
if (unlikely((!rl->length && first_vcn > rl->vcn) ||
first_vcn < rl->vcn))
return -EINVAL;
/*
* @dst_max is used for bounds checking in
* ntfs_write_significant_bytes().
*/
dst_max = dst + dst_len - 1;
prev_lcn = 0;
/* Do the first partial run if present. */
if (first_vcn > rl->vcn) {
s64 delta, length = rl->length;
/* We know rl->length != 0 already. */
if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
goto err_out;
/*
* If @stop_vcn is given and finishes inside this run, cap the
* run length.
*/
if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
s64 s1 = last_vcn + 1;
if (unlikely(rl[1].vcn > s1))
length = s1 - rl->vcn;
the_end = TRUE;
}
delta = first_vcn - rl->vcn;
/* Write length. */
len_len = ntfs_write_significant_bytes(dst + 1, dst_max,
length - delta);
if (unlikely(len_len < 0))
goto size_err;
/*
* If the logical cluster number (lcn) denotes a hole and we
* are on NTFS 3.0+, we don't store it at all, i.e. we need
* zero space. On earlier NTFS versions we just write the lcn
* change. FIXME: Do we need to write the lcn change or just
* the lcn in that case? Not sure as I have never seen this
* case on NT4. - We assume that we just need to write the lcn
* change until someone tells us otherwise... (AIA)
*/
if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
prev_lcn = rl->lcn;
if (likely(rl->lcn >= 0))
prev_lcn += delta;
/* Write change in lcn. */
lcn_len = ntfs_write_significant_bytes(dst + 1 +
len_len, dst_max, prev_lcn);
if (unlikely(lcn_len < 0))
goto size_err;
} else
lcn_len = 0;
dst_next = dst + len_len + lcn_len + 1;
if (unlikely(dst_next > dst_max))
goto size_err;
/* Update header byte. */
*dst = lcn_len << 4 | len_len;
/* Position at next mapping pairs array element. */
dst = dst_next;
/* Go to next runlist element. */
rl++;
}
/* Do the full runs. */
for (; rl->length && !the_end; rl++) {
s64 length = rl->length;
if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
goto err_out;
/*
* If @stop_vcn is given and finishes inside this run, cap the
* run length.
*/
if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
s64 s1 = last_vcn + 1;
if (unlikely(rl[1].vcn > s1))
length = s1 - rl->vcn;
the_end = TRUE;
}
/* Write length. */
len_len = ntfs_write_significant_bytes(dst + 1, dst_max,
length);
if (unlikely(len_len < 0))
goto size_err;
/*
* If the logical cluster number (lcn) denotes a hole and we
* are on NTFS 3.0+, we don't store it at all, i.e. we need
* zero space. On earlier NTFS versions we just write the lcn
* change. FIXME: Do we need to write the lcn change or just
* the lcn in that case? Not sure as I have never seen this
* case on NT4. - We assume that we just need to write the lcn
* change until someone tells us otherwise... (AIA)
*/
if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
/* Write change in lcn. */
lcn_len = ntfs_write_significant_bytes(dst + 1 +
len_len, dst_max, rl->lcn - prev_lcn);
if (unlikely(lcn_len < 0))
goto size_err;
prev_lcn = rl->lcn;
} else
lcn_len = 0;
dst_next = dst + len_len + lcn_len + 1;
if (unlikely(dst_next > dst_max))
goto size_err;
/* Update header byte. */
*dst = lcn_len << 4 | len_len;
/* Position at next mapping pairs array element. */
dst = dst_next;
}
/* Success. */
err = 0;
size_err:
/* Set stop vcn. */
if (stop_vcn)
*stop_vcn = rl->vcn;
/* Add terminator byte. */
*dst = 0;
return err;
err_out:
if (rl->lcn == LCN_RL_NOT_MAPPED)
err = -EINVAL;
else
err = -EIO;
return err;
}
/**
* ntfs_rl_truncate_nolock - truncate a runlist starting at a specified vcn
* @vol: ntfs volume (needed for error output)
* @runlist: runlist to truncate
* @new_length: the new length of the runlist in VCNs
*
* Truncate the runlist described by @runlist as well as the memory buffer
* holding the runlist elements to a length of @new_length VCNs.
*
* If @new_length lies within the runlist, the runlist elements with VCNs of
* @new_length and above are discarded. As a special case if @new_length is
* zero, the runlist is discarded and set to NULL.
*
* If @new_length lies beyond the runlist, a sparse runlist element is added to
* the end of the runlist @runlist or if the last runlist element is a sparse
* one already, this is extended.
*
* Note, no checking is done for unmapped runlist elements. It is assumed that
* the caller has mapped any elements that need to be mapped already.
*
* Return 0 on success and -errno on error.
*
* Locking: The caller must hold @runlist->lock for writing.
*/
int ntfs_rl_truncate_nolock(const ntfs_volume *vol, runlist *const runlist,
const s64 new_length)
{
runlist_element *rl;
int old_size;
ntfs_debug("Entering for new_length 0x%llx.", (long long)new_length);
BUG_ON(!runlist);
BUG_ON(new_length < 0);
rl = runlist->rl;
if (!new_length) {
ntfs_debug("Freeing runlist.");
runlist->rl = NULL;
if (rl)
ntfs_free(rl);
return 0;
}
if (unlikely(!rl)) {
/*
* Create a runlist consisting of a sparse runlist element of
* length @new_length followed by a terminator runlist element.
*/
rl = ntfs_malloc_nofs(PAGE_SIZE);
if (unlikely(!rl)) {
ntfs_error(vol->sb, "Not enough memory to allocate "
"runlist element buffer.");
return -ENOMEM;
}
runlist->rl = rl;
rl[1].length = rl->vcn = 0;
rl->lcn = LCN_HOLE;
rl[1].vcn = rl->length = new_length;
rl[1].lcn = LCN_ENOENT;
return 0;
}
BUG_ON(new_length < rl->vcn);
/* Find @new_length in the runlist. */
while (likely(rl->length && new_length >= rl[1].vcn))
rl++;
/*
* If not at the end of the runlist we need to shrink it.
* If at the end of the runlist we need to expand it.
*/
if (rl->length) {
runlist_element *trl;
BOOL is_end;
ntfs_debug("Shrinking runlist.");
/* Determine the runlist size. */
trl = rl + 1;
while (likely(trl->length))
trl++;
old_size = trl - runlist->rl + 1;
/* Truncate the run. */
rl->length = new_length - rl->vcn;
/*
* If a run was partially truncated, make the following runlist
* element a terminator.
*/
is_end = FALSE;
if (rl->length) {
rl++;
if (!rl->length)
is_end = TRUE;
rl->vcn = new_length;
rl->length = 0;
}
rl->lcn = LCN_ENOENT;
/* Reallocate memory if necessary. */
if (!is_end) {
int new_size = rl - runlist->rl + 1;
rl = ntfs_rl_realloc(runlist->rl, old_size, new_size);
if (IS_ERR(rl))
ntfs_warning(vol->sb, "Failed to shrink "
"runlist buffer. This just "
"wastes a bit of memory "
"temporarily so we ignore it "
"and return success.");
else
runlist->rl = rl;
}
} else if (likely(/* !rl->length && */ new_length > rl->vcn)) {
ntfs_debug("Expanding runlist.");
/*
* If there is a previous runlist element and it is a sparse
* one, extend it. Otherwise need to add a new, sparse runlist
* element.
*/
if ((rl > runlist->rl) && ((rl - 1)->lcn == LCN_HOLE))
(rl - 1)->length = new_length - (rl - 1)->vcn;
else {
/* Determine the runlist size. */
old_size = rl - runlist->rl + 1;
/* Reallocate memory if necessary. */
rl = ntfs_rl_realloc(runlist->rl, old_size,
old_size + 1);
if (IS_ERR(rl)) {
ntfs_error(vol->sb, "Failed to expand runlist "
"buffer, aborting.");
return PTR_ERR(rl);
}
runlist->rl = rl;
/*
* Set @rl to the same runlist element in the new
* runlist as before in the old runlist.
*/
rl += old_size - 1;
/* Add a new, sparse runlist element. */
rl->lcn = LCN_HOLE;
rl->length = new_length - rl->vcn;
/* Add a new terminator runlist element. */
rl++;
rl->length = 0;
}
rl->vcn = new_length;
rl->lcn = LCN_ENOENT;
} else /* if (unlikely(!rl->length && new_length == rl->vcn)) */ {
/* Runlist already has same size as requested. */
rl->lcn = LCN_ENOENT;
}
ntfs_debug("Done.");
return 0;
}
#endif /* NTFS_RW */
