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ntfs-3g/libntfs-3g/compress.c
jpandre c468e74acd Avoided a compiler warning
2009-12-17 09:17:16 +00:00

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/**
* compress.c - Compressed attribute handling code. Originated from the Linux-NTFS
* project.
*
* Copyright (c) 2004-2005 Anton Altaparmakov
* Copyright (c) 2004-2006 Szabolcs Szakacsits
* Copyright (c) 2005 Yura Pakhuchiy
* Copyright (c) 2009 Jean-Pierre Andre
*
* 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 NTFS-3G
* distribution in the file COPYING); if not, write to the Free Software
* Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* A part of the compression algorithm is based on lzhuf.c whose header
* describes the roles of the original authors (with no apparent copyright
* notice, and according to http://home.earthlink.net/~neilbawd/pall.html
* this was put into public domain in 1988 by Haruhiko OKUMURA).
*
* LZHUF.C English version 1.0
* Based on Japanese version 29-NOV-1988
* LZSS coded by Haruhiko OKUMURA
* Adaptive Huffman Coding coded by Haruyasu YOSHIZAKI
* Edited and translated to English by Kenji RIKITAKE
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#ifdef HAVE_STDIO_H
#include <stdio.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#include "attrib.h"
#include "debug.h"
#include "volume.h"
#include "types.h"
#include "layout.h"
#include "runlist.h"
#include "compress.h"
#include "lcnalloc.h"
#include "logging.h"
#include "misc.h"
/**
* enum ntfs_compression_constants - constants used in the compression code
*/
typedef enum {
/* Token types and access mask. */
NTFS_SYMBOL_TOKEN = 0,
NTFS_PHRASE_TOKEN = 1,
NTFS_TOKEN_MASK = 1,
/* Compression sub-block constants. */
NTFS_SB_SIZE_MASK = 0x0fff,
NTFS_SB_SIZE = 0x1000,
NTFS_SB_IS_COMPRESSED = 0x8000,
} ntfs_compression_constants;
#define THRESHOLD 3 /* minimal match length for compression */
#define NIL NTFS_SB_SIZE /* End of tree's node */
struct COMPRESS_CONTEXT {
const unsigned char *inbuf;
unsigned int len;
unsigned int nbt;
int match_position;
unsigned int match_length;
u16 lson[NTFS_SB_SIZE + 1];
u16 rson[NTFS_SB_SIZE + 257];
u16 dad[NTFS_SB_SIZE + 1];
} ;
/*
* Initialize the match tree
*/
static void ntfs_init_compress_tree(struct COMPRESS_CONTEXT *pctx)
{
int i;
for (i = NTFS_SB_SIZE + 1; i <= NTFS_SB_SIZE + 256; i++)
pctx->rson[i] = NIL; /* root */
for (i = 0; i < NTFS_SB_SIZE; i++)
pctx->dad[i] = NIL; /* node */
}
/*
* Insert a new node into match tree for quickly locating
* further similar strings
*/
static void ntfs_new_node (struct COMPRESS_CONTEXT *pctx,
unsigned int r)
{
unsigned int pp;
BOOL less;
BOOL done;
const unsigned char *key;
int c;
unsigned int mxi;
unsigned int mxl;
mxl = (1 << (16 - pctx->nbt)) + 2;
less = FALSE;
done = FALSE;
key = &pctx->inbuf[r];
pp = NTFS_SB_SIZE + 1 + key[0];
pctx->rson[r] = pctx->lson[r] = NIL;
pctx->match_length = 0;
do {
if (!less) {
if (pctx->rson[pp] != NIL)
pp = pctx->rson[pp];
else {
pctx->rson[pp] = r;
pctx->dad[r] = pp;
done = TRUE;
}
} else {
if (pctx->lson[pp] != NIL)
pp = pctx->lson[pp];
else {
pctx->lson[pp] = r;
pctx->dad[r] = pp;
done = TRUE;
}
}
if (!done) {
register unsigned int i;
register const unsigned char *p1,*p2;
i = 1;
p1 = key;
p2 = &pctx->inbuf[pp];
mxi = NTFS_SB_SIZE - r;
do {
} while ((p1[i] == p2[i]) && (++i < mxi));
less = (i < mxi) && (p1[i] < p2[i]);
if (i >= THRESHOLD) {
if (i > pctx->match_length) {
pctx->match_position =
r - pp + 2*NTFS_SB_SIZE - 1;
if ((pctx->match_length = i) > mxl) {
i = pctx->rson[pp];
pctx->rson[r] = i;
pctx->dad[i] = r;
i = pctx->lson[pp];
pctx->lson[r] = i;
pctx->dad[i] = r;
i = pctx->dad[pp];
pctx->dad[r] = i;
if (pctx->rson[i] == pp)
pctx->rson[i] = r;
else
pctx->lson[i] = r;
pctx->dad[pp] = NIL; /* remove pp */
done = TRUE;
pctx->match_length = mxl;
}
} else
if ((i == pctx->match_length)
&& ((c = (r - pp + 2*NTFS_SB_SIZE - 1))
< pctx->match_position))
pctx->match_position = c;
}
}
} while (!done);
}
/*
* Search for the longest previous string matching the
* current one
*
* Returns the end of the longest current string which matched
* or zero if there was a bug
*/
static unsigned int ntfs_nextmatch(struct COMPRESS_CONTEXT *pctx, unsigned int rr, int dd)
{
unsigned int bestlen = 0;
do {
rr++;
if (pctx->match_length > 0)
pctx->match_length--;
if (!pctx->len) {
ntfs_log_error("compress bug : void run\n");
goto bug;
}
if (--pctx->len) {
if (rr >= NTFS_SB_SIZE) {
ntfs_log_error("compress bug : buffer overflow\n");
goto bug;
}
if (((rr + bestlen) < NTFS_SB_SIZE)) {
while ((unsigned int)(1 << pctx->nbt) <= (rr - 1))
pctx->nbt++;
ntfs_new_node(pctx,rr);
if (pctx->match_length > bestlen)
bestlen = pctx->match_length;
} else
if (dd > 0) {
rr += dd;
if ((int)pctx->match_length > dd)
pctx->match_length -= dd;
else
pctx->match_length = 0;
if ((int)pctx->len < dd) {
ntfs_log_error("compress bug : run overflows\n");
goto bug;
}
pctx->len -= dd;
dd = 0;
}
}
} while (dd-- > 0);
return (rr);
bug :
return (0);
}
/*
* Compress an input block
*
* Returns the size of the compressed block (including header)
* or zero if there was an error
*/
static unsigned int ntfs_compress_block(const char *inbuf, unsigned int size, char *outbuf)
{
struct COMPRESS_CONTEXT *pctx;
char *ptag;
int dd;
unsigned int rr;
unsigned int last_match_length;
unsigned int q;
unsigned int xout;
unsigned int ntag;
pctx = (struct COMPRESS_CONTEXT*)malloc(sizeof(struct COMPRESS_CONTEXT));
if (pctx) {
pctx->inbuf = (const unsigned char*)inbuf;
ntfs_init_compress_tree(pctx);
xout = 2;
ntag = 0;
ptag = &outbuf[xout++];
*ptag = 0;
rr = 0;
pctx->nbt = 4;
pctx->len = size;
pctx->match_length = 0;
ntfs_new_node(pctx,0);
do {
if (pctx->match_length > pctx->len)
pctx->match_length = pctx->len;
if (pctx->match_length < THRESHOLD) {
pctx->match_length = 1;
if (ntag >= 8) {
ntag = 0;
ptag = &outbuf[xout++];
*ptag = 0;
}
outbuf[xout++] = inbuf[rr];
ntag++;
} else {
while ((unsigned int)(1 << pctx->nbt) <= (rr - 1))
pctx->nbt++;
q = (pctx->match_position << (16 - pctx->nbt))
+ pctx->match_length - THRESHOLD;
if (ntag >= 8) {
ntag = 0;
ptag = &outbuf[xout++];
*ptag = 0;
}
*ptag |= 1 << ntag++;
outbuf[xout++] = q & 255;
outbuf[xout++] = (q >> 8) & 255;
}
last_match_length = pctx->match_length;
dd = last_match_length;
if (dd-- > 0) {
rr = ntfs_nextmatch(pctx,rr,dd);
if (!rr)
goto bug;
}
/*
* stop if input is exhausted or output has exceeded
* the maximum size. Two extra bytes have to be
* reserved in output buffer, as 3 bytes may be
* output in a loop.
*/
} while ((pctx->len > 0)
&& (rr < size) && (xout < (NTFS_SB_SIZE + 2)));
/* uncompressed must be full size, so accept if better */
if (xout < (NTFS_SB_SIZE + 2)) {
outbuf[0] = (xout - 3) & 255;
outbuf[1] = 0xb0 + (((xout - 3) >> 8) & 15);
} else {
memcpy(&outbuf[2],inbuf,size);
if (size < NTFS_SB_SIZE)
memset(&outbuf[size+2],0,NTFS_SB_SIZE - size);
outbuf[0] = 0xff;
outbuf[1] = 0x3f;
xout = NTFS_SB_SIZE + 2;
}
free(pctx);
} else {
xout = 0;
errno = ENOMEM;
}
return (xout); /* 0 for an error, > size if cannot compress */
bug :
return (0);
}
/**
* ntfs_decompress - decompress a compression block into an array of pages
* @dest: buffer to which to write the decompressed data
* @dest_size: size of buffer @dest in bytes
* @cb_start: compression block to decompress
* @cb_size: size of compression block @cb_start in bytes
*
* This decompresses the compression block @cb_start into the destination
* buffer @dest.
*
* @cb_start is a pointer to the compression block which needs decompressing
* and @cb_size is the size of @cb_start in bytes (8-64kiB).
*
* Return 0 if success or -EOVERFLOW on error in the compressed stream.
*/
static int ntfs_decompress(u8 *dest, const u32 dest_size,
u8 *const cb_start, const u32 cb_size)
{
/*
* Pointers into the compressed data, i.e. the compression block (cb),
* and the therein contained sub-blocks (sb).
*/
u8 *cb_end = cb_start + cb_size; /* End of cb. */
u8 *cb = cb_start; /* Current position in cb. */
u8 *cb_sb_start = cb; /* Beginning of the current sb in the cb. */
u8 *cb_sb_end; /* End of current sb / beginning of next sb. */
/* Variables for uncompressed data / destination. */
u8 *dest_end = dest + dest_size; /* End of dest buffer. */
u8 *dest_sb_start; /* Start of current sub-block in dest. */
u8 *dest_sb_end; /* End of current sb in dest. */
/* Variables for tag and token parsing. */
u8 tag; /* Current tag. */
int token; /* Loop counter for the eight tokens in tag. */
ntfs_log_trace("Entering, cb_size = 0x%x.\n", (unsigned)cb_size);
do_next_sb:
ntfs_log_debug("Beginning sub-block at offset = %d in the cb.\n",
(int)(cb - cb_start));
/*
* Have we reached the end of the compression block or the end of the
* decompressed data? The latter can happen for example if the current
* position in the compression block is one byte before its end so the
* first two checks do not detect it.
*/
if (cb == cb_end || !le16_to_cpup((le16*)cb) || dest == dest_end) {
ntfs_log_debug("Completed. Returning success (0).\n");
return 0;
}
/* Setup offset for the current sub-block destination. */
dest_sb_start = dest;
dest_sb_end = dest + NTFS_SB_SIZE;
/* Check that we are still within allowed boundaries. */
if (dest_sb_end > dest_end)
goto return_overflow;
/* Does the minimum size of a compressed sb overflow valid range? */
if (cb + 6 > cb_end)
goto return_overflow;
/* Setup the current sub-block source pointers and validate range. */
cb_sb_start = cb;
cb_sb_end = cb_sb_start + (le16_to_cpup((le16*)cb) & NTFS_SB_SIZE_MASK)
+ 3;
if (cb_sb_end > cb_end)
goto return_overflow;
/* Now, we are ready to process the current sub-block (sb). */
if (!(le16_to_cpup((le16*)cb) & NTFS_SB_IS_COMPRESSED)) {
ntfs_log_debug("Found uncompressed sub-block.\n");
/* This sb is not compressed, just copy it into destination. */
/* Advance source position to first data byte. */
cb += 2;
/* An uncompressed sb must be full size. */
if (cb_sb_end - cb != NTFS_SB_SIZE)
goto return_overflow;
/* Copy the block and advance the source position. */
memcpy(dest, cb, NTFS_SB_SIZE);
cb += NTFS_SB_SIZE;
/* Advance destination position to next sub-block. */
dest += NTFS_SB_SIZE;
goto do_next_sb;
}
ntfs_log_debug("Found compressed sub-block.\n");
/* This sb is compressed, decompress it into destination. */
/* Forward to the first tag in the sub-block. */
cb += 2;
do_next_tag:
if (cb == cb_sb_end) {
/* Check if the decompressed sub-block was not full-length. */
if (dest < dest_sb_end) {
int nr_bytes = dest_sb_end - dest;
ntfs_log_debug("Filling incomplete sub-block with zeroes.\n");
/* Zero remainder and update destination position. */
memset(dest, 0, nr_bytes);
dest += nr_bytes;
}
/* We have finished the current sub-block. */
goto do_next_sb;
}
/* Check we are still in range. */
if (cb > cb_sb_end || dest > dest_sb_end)
goto return_overflow;
/* Get the next tag and advance to first token. */
tag = *cb++;
/* Parse the eight tokens described by the tag. */
for (token = 0; token < 8; token++, tag >>= 1) {
u16 lg, pt, length, max_non_overlap;
register u16 i;
u8 *dest_back_addr;
/* Check if we are done / still in range. */
if (cb >= cb_sb_end || dest > dest_sb_end)
break;
/* Determine token type and parse appropriately.*/
if ((tag & NTFS_TOKEN_MASK) == NTFS_SYMBOL_TOKEN) {
/*
* We have a symbol token, copy the symbol across, and
* advance the source and destination positions.
*/
*dest++ = *cb++;
/* Continue with the next token. */
continue;
}
/*
* We have a phrase token. Make sure it is not the first tag in
* the sb as this is illegal and would confuse the code below.
*/
if (dest == dest_sb_start)
goto return_overflow;
/*
* Determine the number of bytes to go back (p) and the number
* of bytes to copy (l). We use an optimized algorithm in which
* we first calculate log2(current destination position in sb),
* which allows determination of l and p in O(1) rather than
* O(n). We just need an arch-optimized log2() function now.
*/
lg = 0;
for (i = dest - dest_sb_start - 1; i >= 0x10; i >>= 1)
lg++;
/* Get the phrase token into i. */
pt = le16_to_cpup((le16*)cb);
/*
* Calculate starting position of the byte sequence in
* the destination using the fact that p = (pt >> (12 - lg)) + 1
* and make sure we don't go too far back.
*/
dest_back_addr = dest - (pt >> (12 - lg)) - 1;
if (dest_back_addr < dest_sb_start)
goto return_overflow;
/* Now calculate the length of the byte sequence. */
length = (pt & (0xfff >> lg)) + 3;
/* Verify destination is in range. */
if (dest + length > dest_sb_end)
goto return_overflow;
/* The number of non-overlapping bytes. */
max_non_overlap = dest - dest_back_addr;
if (length <= max_non_overlap) {
/* The byte sequence doesn't overlap, just copy it. */
memcpy(dest, dest_back_addr, length);
/* Advance destination pointer. */
dest += length;
} else {
/*
* The byte sequence does overlap, copy non-overlapping
* part and then do a slow byte by byte copy for the
* overlapping part. Also, advance the destination
* pointer.
*/
memcpy(dest, dest_back_addr, max_non_overlap);
dest += max_non_overlap;
dest_back_addr += max_non_overlap;
length -= max_non_overlap;
while (length--)
*dest++ = *dest_back_addr++;
}
/* Advance source position and continue with the next token. */
cb += 2;
}
/* No tokens left in the current tag. Continue with the next tag. */
goto do_next_tag;
return_overflow:
errno = EOVERFLOW;
ntfs_log_perror("Failed to decompress file");
return -1;
}
/**
* ntfs_is_cb_compressed - internal function, do not use
*
* This is a very specialised function determining if a cb is compressed or
* uncompressed. It is assumed that checking for a sparse cb has already been
* performed and that the cb is not sparse. It makes all sorts of other
* assumptions as well and hence it is not useful anywhere other than where it
* is used at the moment. Please, do not make this function available for use
* outside of compress.c as it is bound to confuse people and not do what they
* want.
*
* Return TRUE on errors so that the error will be detected later on in the
* code. Might be a bit confusing to debug but there really should never be
* errors coming from here.
*/
static BOOL ntfs_is_cb_compressed(ntfs_attr *na, runlist_element *rl,
VCN cb_start_vcn, int cb_clusters)
{
/*
* The simplest case: the run starting at @cb_start_vcn contains
* @cb_clusters clusters which are all not sparse, thus the cb is not
* compressed.
*/
restart:
cb_clusters -= rl->length - (cb_start_vcn - rl->vcn);
while (cb_clusters > 0) {
/* Go to the next run. */
rl++;
/* Map the next runlist fragment if it is not mapped. */
if (rl->lcn < LCN_HOLE || !rl->length) {
cb_start_vcn = rl->vcn;
rl = ntfs_attr_find_vcn(na, rl->vcn);
if (!rl || rl->lcn < LCN_HOLE || !rl->length)
return TRUE;
/*
* If the runs were merged need to deal with the
* resulting partial run so simply restart.
*/
if (rl->vcn < cb_start_vcn)
goto restart;
}
/* If the current run is sparse, the cb is compressed. */
if (rl->lcn == LCN_HOLE)
return TRUE;
/* If the whole cb is not sparse, it is not compressed. */
if (rl->length >= cb_clusters)
return FALSE;
cb_clusters -= rl->length;
};
/* All cb_clusters were not sparse thus the cb is not compressed. */
return FALSE;
}
/**
* ntfs_compressed_attr_pread - read from a compressed attribute
* @na: ntfs attribute to read from
* @pos: byte position in the attribute to begin reading from
* @count: number of bytes to read
* @b: output data buffer
*
* NOTE: You probably want to be using attrib.c::ntfs_attr_pread() instead.
*
* This function will read @count bytes starting at offset @pos from the
* compressed ntfs attribute @na into the data buffer @b.
*
* On success, return the number of successfully read bytes. If this number
* is lower than @count this means that the read reached end of file or that
* an error was encountered during the read so that the read is partial.
* 0 means end of file or nothing was read (also return 0 when @count is 0).
*
* On error and nothing has been read, return -1 with errno set appropriately
* to the return code of ntfs_pread(), or to EINVAL in case of invalid
* arguments.
*/
s64 ntfs_compressed_attr_pread(ntfs_attr *na, s64 pos, s64 count, void *b)
{
s64 br, to_read, ofs, total, total2;
u64 cb_size_mask;
VCN start_vcn, vcn, end_vcn;
ntfs_volume *vol;
runlist_element *rl;
u8 *dest, *cb, *cb_pos, *cb_end;
u32 cb_size;
int err;
ATTR_FLAGS data_flags;
FILE_ATTR_FLAGS compression;
unsigned int nr_cbs, cb_clusters;
ntfs_log_trace("Entering for inode 0x%llx, attr 0x%x, pos 0x%llx, count 0x%llx.\n",
(unsigned long long)na->ni->mft_no, na->type,
(long long)pos, (long long)count);
data_flags = na->data_flags;
compression = na->ni->flags & FILE_ATTR_COMPRESSED;
if (!na || !na->ni || !na->ni->vol || !b
|| ((data_flags & ATTR_COMPRESSION_MASK)
!= ATTR_IS_COMPRESSED)
|| pos < 0 || count < 0) {
errno = EINVAL;
return -1;
}
/*
* Encrypted attributes are not supported. We return access denied,
* which is what Windows NT4 does, too.
*/
if (NAttrEncrypted(na)) {
errno = EACCES;
return -1;
}
if (!count)
return 0;
/* Truncate reads beyond end of attribute. */
if (pos + count > na->data_size) {
if (pos >= na->data_size) {
return 0;
}
count = na->data_size - pos;
}
/* If it is a resident attribute, simply use ntfs_attr_pread(). */
if (!NAttrNonResident(na))
return ntfs_attr_pread(na, pos, count, b);
total = total2 = 0;
/* Zero out reads beyond initialized size. */
if (pos + count > na->initialized_size) {
if (pos >= na->initialized_size) {
memset(b, 0, count);
return count;
}
total2 = pos + count - na->initialized_size;
count -= total2;
memset((u8*)b + count, 0, total2);
}
vol = na->ni->vol;
cb_size = na->compression_block_size;
cb_size_mask = cb_size - 1UL;
cb_clusters = na->compression_block_clusters;
/* Need a temporary buffer for each loaded compression block. */
cb = (u8*)ntfs_malloc(cb_size);
if (!cb)
return -1;
/* Need a temporary buffer for each uncompressed block. */
dest = (u8*)ntfs_malloc(cb_size);
if (!dest) {
free(cb);
return -1;
}
/*
* The first vcn in the first compression block (cb) which we need to
* decompress.
*/
start_vcn = (pos & ~cb_size_mask) >> vol->cluster_size_bits;
/* Offset in the uncompressed cb at which to start reading data. */
ofs = pos & cb_size_mask;
/*
* The first vcn in the cb after the last cb which we need to
* decompress.
*/
end_vcn = ((pos + count + cb_size - 1) & ~cb_size_mask) >>
vol->cluster_size_bits;
/* Number of compression blocks (cbs) in the wanted vcn range. */
nr_cbs = (end_vcn - start_vcn) << vol->cluster_size_bits >>
na->compression_block_size_bits;
cb_end = cb + cb_size;
do_next_cb:
nr_cbs--;
cb_pos = cb;
vcn = start_vcn;
start_vcn += cb_clusters;
/* Check whether the compression block is sparse. */
rl = ntfs_attr_find_vcn(na, vcn);
if (!rl || rl->lcn < LCN_HOLE) {
free(cb);
free(dest);
if (total)
return total;
/* FIXME: Do we want EIO or the error code? (AIA) */
errno = EIO;
return -1;
}
if (rl->lcn == LCN_HOLE) {
/* Sparse cb, zero out destination range overlapping the cb. */
ntfs_log_debug("Found sparse compression block.\n");
to_read = min(count, cb_size - ofs);
memset(b, 0, to_read);
ofs = 0;
total += to_read;
count -= to_read;
b = (u8*)b + to_read;
} else if (!ntfs_is_cb_compressed(na, rl, vcn, cb_clusters)) {
s64 tdata_size, tinitialized_size;
/*
* Uncompressed cb, read it straight into the destination range
* overlapping the cb.
*/
ntfs_log_debug("Found uncompressed compression block.\n");
/*
* Read the uncompressed data into the destination buffer.
* NOTE: We cheat a little bit here by marking the attribute as
* not compressed in the ntfs_attr structure so that we can
* read the data by simply using ntfs_attr_pread(). (-8
* NOTE: we have to modify data_size and initialized_size
* temporarily as well...
*/
to_read = min(count, cb_size - ofs);
ofs += vcn << vol->cluster_size_bits;
NAttrClearCompressed(na);
na->data_flags &= ~ATTR_COMPRESSION_MASK;
tdata_size = na->data_size;
tinitialized_size = na->initialized_size;
na->data_size = na->initialized_size = na->allocated_size;
do {
br = ntfs_attr_pread(na, ofs, to_read, b);
if (br < 0) {
err = errno;
na->data_size = tdata_size;
na->initialized_size = tinitialized_size;
na->ni->flags |= compression;
na->data_flags = data_flags;
free(cb);
free(dest);
if (total)
return total;
errno = err;
return br;
}
total += br;
count -= br;
b = (u8*)b + br;
to_read -= br;
ofs += br;
} while (to_read > 0);
na->data_size = tdata_size;
na->initialized_size = tinitialized_size;
na->ni->flags |= compression;
na->data_flags = data_flags;
ofs = 0;
} else {
s64 tdata_size, tinitialized_size;
/*
* Compressed cb, decompress it into the temporary buffer, then
* copy the data to the destination range overlapping the cb.
*/
ntfs_log_debug("Found compressed compression block.\n");
/*
* Read the compressed data into the temporary buffer.
* NOTE: We cheat a little bit here by marking the attribute as
* not compressed in the ntfs_attr structure so that we can
* read the raw, compressed data by simply using
* ntfs_attr_pread(). (-8
* NOTE: We have to modify data_size and initialized_size
* temporarily as well...
*/
to_read = cb_size;
NAttrClearCompressed(na);
na->data_flags &= ~ATTR_COMPRESSION_MASK;
tdata_size = na->data_size;
tinitialized_size = na->initialized_size;
na->data_size = na->initialized_size = na->allocated_size;
do {
br = ntfs_attr_pread(na,
(vcn << vol->cluster_size_bits) +
(cb_pos - cb), to_read, cb_pos);
if (br < 0) {
err = errno;
na->data_size = tdata_size;
na->initialized_size = tinitialized_size;
na->ni->flags |= compression;
na->data_flags = data_flags;
free(cb);
free(dest);
if (total)
return total;
errno = err;
return br;
}
cb_pos += br;
to_read -= br;
} while (to_read > 0);
na->data_size = tdata_size;
na->initialized_size = tinitialized_size;
na->ni->flags |= compression;
na->data_flags = data_flags;
/* Just a precaution. */
if (cb_pos + 2 <= cb_end)
*(u16*)cb_pos = 0;
ntfs_log_debug("Successfully read the compression block.\n");
if (ntfs_decompress(dest, cb_size, cb, cb_size) < 0) {
err = errno;
free(cb);
free(dest);
if (total)
return total;
errno = err;
return -1;
}
to_read = min(count, cb_size - ofs);
memcpy(b, dest + ofs, to_read);
total += to_read;
count -= to_read;
b = (u8*)b + to_read;
ofs = 0;
}
/* Do we have more work to do? */
if (nr_cbs)
goto do_next_cb;
/* We no longer need the buffers. */
free(cb);
free(dest);
/* Return number of bytes read. */
return total + total2;
}
/*
* Read data from a set of clusters
*
* Returns the amount of data read
*/
static u32 read_clusters(ntfs_volume *vol, const runlist_element *rl,
s64 offs, u32 to_read, char *inbuf)
{
u32 count;
int xgot;
u32 got;
s64 xpos;
BOOL first;
char *xinbuf;
const runlist_element *xrl;
got = 0;
xrl = rl;
xinbuf = inbuf;
first = TRUE;
do {
count = xrl->length << vol->cluster_size_bits;
xpos = xrl->lcn << vol->cluster_size_bits;
if (first) {
count -= offs;
xpos += offs;
}
if ((to_read - got) < count)
count = to_read - got;
xgot = ntfs_pread(vol->dev, xpos, count, xinbuf);
if (xgot == (int)count) {
got += count;
xpos += count;
xinbuf += count;
xrl++;
}
first = FALSE;
} while ((xgot == (int)count) && (got < to_read));
return (got);
}
/*
* Write data to a set of clusters
*
* Returns the amount of data written
*/
static int write_clusters(ntfs_volume *vol, const runlist_element *rl,
s64 offs, int to_write, const char *outbuf)
{
int count;
int put, xput;
s64 xpos;
BOOL first;
const char *xoutbuf;
const runlist_element *xrl;
put = 0;
xrl = rl;
xoutbuf = outbuf;
first = TRUE;
do {
count = xrl->length << vol->cluster_size_bits;
xpos = xrl->lcn << vol->cluster_size_bits;
if (first) {
count -= offs;
xpos += offs;
}
if ((to_write - put) < count)
count = to_write - put;
xput = ntfs_pwrite(vol->dev, xpos, count, xoutbuf);
if (xput == count) {
put += count;
xpos += count;
xoutbuf += count;
xrl++;
}
first = FALSE;
} while ((xput == count) && (put < to_write));
return (put);
}
/*
* Compress and write a set of blocks
*
* returns the size actually written (rounded to a full cluster)
* or 0 if all zeroes (nothing is written)
* or -1 if could not compress (nothing is written)
* or -2 if there were an irrecoverable error (errno set)
*/
static int ntfs_comp_set(ntfs_attr *na, runlist_element *rl,
s64 offs, unsigned int insz, const char *inbuf)
{
ntfs_volume *vol;
char *outbuf;
char *pbuf;
unsigned int compsz;
int written;
int rounded;
unsigned int clsz;
unsigned int p;
unsigned int sz;
unsigned int bsz;
BOOL fail;
BOOL allzeroes;
/* a single compressed zero */
static char onezero[] = { 0x01, 0xb0, 0x00, 0x00 } ;
/* a couple of compressed zeroes */
static char twozeroes[] = { 0x02, 0xb0, 0x00, 0x00, 0x00 } ;
/* more compressed zeroes, to be followed by some count */
static char morezeroes[] = { 0x03, 0xb0, 0x02, 0x00 } ;
vol = na->ni->vol;
written = -1; /* default return */
clsz = 1 << vol->cluster_size_bits;
/* may need 2 extra bytes per block and 2 more bytes */
outbuf = (char*)ntfs_malloc(na->compression_block_size
+ 2*(na->compression_block_size/NTFS_SB_SIZE)
+ 2);
if (outbuf) {
fail = FALSE;
compsz = 0;
allzeroes = TRUE;
for (p=0; (p<insz) && !fail; p+=NTFS_SB_SIZE) {
if ((p + NTFS_SB_SIZE) < insz)
bsz = NTFS_SB_SIZE;
else
bsz = insz - p;
pbuf = &outbuf[compsz];
sz = ntfs_compress_block(&inbuf[p],bsz,pbuf);
/* fail if all the clusters (or more) are needed */
if (!sz || ((compsz + sz + clsz + 2)
> na->compression_block_size))
fail = TRUE;
else {
if (allzeroes) {
/* check whether this is all zeroes */
switch (sz) {
case 4 :
allzeroes = !memcmp(
pbuf,onezero,4);
break;
case 5 :
allzeroes = !memcmp(
pbuf,twozeroes,5);
break;
case 6 :
allzeroes = !memcmp(
pbuf,morezeroes,4);
break;
default :
allzeroes = FALSE;
break;
}
}
compsz += sz;
}
}
if (!fail && !allzeroes) {
/* add a couple of null bytes, space has been checked */
outbuf[compsz++] = 0;
outbuf[compsz++] = 0;
/* write a full cluster, to avoid partial reading */
rounded = ((compsz - 1) | (clsz - 1)) + 1;
written = write_clusters(vol, rl, offs, rounded, outbuf);
if (written != rounded) {
// previously written text has been spoilt, should return a specific error
ntfs_log_error("error writing compressed data\n");
errno = EIO;
written = -2;
}
} else
if (!fail)
written = 0;
free(outbuf);
}
return (written);
}
/*
* Free unneeded clusters after compression
*
* This generally requires an empty slot at the end of runlist,
* but we do not want to reallocate the runlist here because
* there are many pointers to it.
* So the empty slot has to be reserved beforehand
*
* Returns zero unless some error occurred (described by errno)
*/
static int ntfs_compress_free(ntfs_attr *na, runlist_element *rl,
s64 used, s64 reserved)
{
int freecnt;
int usedcnt;
int res;
s64 freelcn;
s64 freevcn;
int freelength;
BOOL mergeholes;
BOOL beginhole;
ntfs_volume *vol;
runlist_element *freerl;
res = -1; /* default return */
vol = na->ni->vol;
freecnt = (reserved - used) >> vol->cluster_size_bits;
usedcnt = (reserved >> vol->cluster_size_bits) - freecnt;
/* skip entries fully used, if any */
while (rl->length && (rl->length < usedcnt)) {
usedcnt -= rl->length;
rl++;
}
if (rl->length) {
/*
* Splitting the current allocation block requires
* an extra runlist element to create the hole.
* The required entry has been prereserved when
* mapping the runlist.
*/
freelcn = rl->lcn + usedcnt;
freevcn = rl->vcn + usedcnt;
freelength = rl->length - usedcnt;
/* new count of allocated clusters */
rl->length = usedcnt; /* warning : can be zero */
if (!((freevcn + freecnt)
& (na->compression_block_clusters - 1))) {
beginhole = !usedcnt && !rl->vcn;
mergeholes = !usedcnt
&& rl[0].vcn
&& (rl[-1].lcn == LCN_HOLE);
if (mergeholes) {
freerl = rl;
freerl->length = freecnt;
} else
freerl = ++rl;
if ((freelength > 0)
&& !mergeholes
&& (usedcnt || beginhole)) {
/*
* move the unused part to the end. Doing so,
* the vcn will be out of order. This does
* not harm, the vcn are meaningless now, and
* only the lcn are meaningful for freeing.
*/
/* locate current end */
while (rl->length)
rl++;
/* new terminator relocated */
rl[1].vcn = rl->vcn;
rl[1].lcn = LCN_ENOENT;
rl[1].length = 0;
/* hole, currently allocated */
rl->vcn = freevcn;
rl->lcn = freelcn;
rl->length = freelength;
}
/* free the hole */
res = ntfs_cluster_free_from_rl(vol,freerl);
if (!res) {
if (mergeholes) {
/* merge with adjacent hole */
freerl--;
freerl->length += freecnt;
} else {
if (beginhole)
freerl--;
/* mark hole as free */
freerl->lcn = LCN_HOLE;
freerl->vcn = freevcn;
freerl->length = freecnt;
}
/* and set up the new end */
freerl[1].lcn = LCN_ENOENT;
freerl[1].vcn = freevcn + freecnt;
freerl[1].length = 0;
}
} else {
ntfs_log_error("Bad end of a compression block set\n");
errno = EIO;
}
} else {
ntfs_log_error("No cluster to free after compression\n");
errno = EIO;
}
return (res);
}
/*
* Read existing data, decompress and append buffer
* Do nothing if something fails
*/
static int ntfs_read_append(ntfs_attr *na, const runlist_element *rl,
s64 offs, u32 compsz, int pos,
char *outbuf, s64 to_write, const void *b)
{
int fail = 1;
char *compbuf;
u32 decompsz;
u32 got;
if (compsz == na->compression_block_size) {
/* if the full block was requested, it was a hole */
memset(outbuf,0,compsz);
memcpy(&outbuf[pos],b,to_write);
fail = 0;
} else {
compbuf = (char*)ntfs_malloc(compsz);
if (compbuf) {
/* must align to full block for decompression */
decompsz = ((pos - 1) | (NTFS_SB_SIZE - 1)) + 1;
got = read_clusters(na->ni->vol, rl, offs,
compsz, compbuf);
if ((got == compsz)
&& !ntfs_decompress((u8*)outbuf,decompsz,
(u8*)compbuf,compsz)) {
memcpy(&outbuf[pos],b,to_write);
fail = 0;
}
free(compbuf);
}
}
return (fail);
}
/*
* Flush a full compression block
*
* returns the size actually written (rounded to a full cluster)
* or 0 if could not compress (and written uncompressed)
* or -1 if there were an irrecoverable error (errno set)
*/
static int ntfs_flush(ntfs_attr *na, runlist_element *rl, s64 offs,
const char *outbuf, int count, BOOL compress)
{
int rounded;
int written;
int clsz;
if (compress) {
written = ntfs_comp_set(na, rl, offs, count, outbuf);
if (written == -1)
compress = FALSE;
if ((written >= 0)
&& ntfs_compress_free(na,rl,offs + written,
offs + na->compression_block_size))
written = -1;
} else
written = 0;
if (!compress) {
clsz = 1 << na->ni->vol->cluster_size_bits;
rounded = ((count - 1) | (clsz - 1)) + 1;
written = write_clusters(na->ni->vol, rl,
offs, rounded, outbuf);
if (written != rounded)
written = -1;
}
return (written);
}
/*
* Write some data to be compressed.
* Compression only occurs when a few clusters (usually 16) are
* full. When this occurs an extra runlist slot may be needed, so
* it has to be reserved beforehand.
*
* Returns the size of uncompressed data written,
* or zero if an error occurred.
* When the returned size is less than requested, new clusters have
* to be allocated before the function is called again.
*/
s64 ntfs_compressed_pwrite(ntfs_attr *na, runlist_element *wrl, s64 wpos,
s64 offs, s64 to_write, s64 rounded,
const void *b, int compressed_part)
{
ntfs_volume *vol;
runlist_element *brl; /* entry containing the beginning of block */
int compression_length;
s64 written;
s64 to_read;
s64 roffs;
s64 got;
s64 start_vcn;
s64 nextblock;
u32 compsz;
char *inbuf;
char *outbuf;
BOOL fail;
BOOL done;
BOOL compress;
written = 0; /* default return */
vol = na->ni->vol;
compression_length = na->compression_block_clusters;
compress = FALSE;
done = FALSE;
/*
* Cannot accept writing beyond the current compression set
* because when compression occurs, clusters are freed
* and have to be reallocated.
* (cannot happen with standard fuse 4K buffers)
* Caller has to avoid this situation, or face consequences.
*/
nextblock = ((offs + (wrl->vcn << vol->cluster_size_bits))
| (na->compression_block_size - 1)) + 1;
if ((offs + to_write + (wrl->vcn << vol->cluster_size_bits))
>= nextblock) {
/* it is time to compress */
compress = TRUE;
/* only process what we can */
to_write = rounded = nextblock
- (offs + (wrl->vcn << vol->cluster_size_bits));
}
start_vcn = 0;
fail = FALSE;
brl = wrl;
roffs = 0;
/*
* If we are about to compress or we need to decompress
* existing data, we have to process a full set of blocks.
* So relocate the parameters to the beginning of allocation
* containing the first byte of the set of blocks.
*/
if (compress || compressed_part) {
/* find the beginning of block */
start_vcn = (wrl->vcn + (offs >> vol->cluster_size_bits))
& -compression_length;
while (brl->vcn && (brl->vcn > start_vcn)) {
/* jumping back a hole means big trouble */
if (brl->lcn == (LCN)LCN_HOLE) {
ntfs_log_error("jump back over a hole when appending\n");
fail = TRUE;
errno = EIO;
}
brl--;
offs += brl->length << vol->cluster_size_bits;
}
roffs = (start_vcn - brl->vcn) << vol->cluster_size_bits;
}
if (compressed_part && !fail) {
/*
* The set of compression blocks contains compressed data
* (we are reopening an existing file to append to it)
* Decompress the data and append
*/
compsz = compressed_part << vol->cluster_size_bits;
// improve the needed size
outbuf = (char*)ntfs_malloc(na->compression_block_size);
if (outbuf) {
to_read = offs - roffs;
if (!ntfs_read_append(na, brl, roffs, compsz,
to_read, outbuf, to_write, b)) {
written = ntfs_flush(na, brl, roffs,
outbuf, to_read + to_write, compress);
if (written >= 0) {
written = to_write;
done = TRUE;
}
}
free(outbuf);
}
} else {
if (compress && !fail) {
/*
* we are filling up a block, read the full set of blocks
* and compress it
*/
inbuf = (char*)ntfs_malloc(na->compression_block_size);
if (inbuf) {
to_read = offs - roffs;
if (to_read)
got = read_clusters(vol, brl, roffs,
to_read, inbuf);
else
got = 0;
if (got == to_read) {
memcpy(&inbuf[to_read],b,to_write);
written = ntfs_comp_set(na, brl, roffs,
to_read + to_write, inbuf);
/*
* if compression was not successful,
* only write the part which was requested
*/
if ((written >= 0)
/* free the unused clusters */
&& !ntfs_compress_free(na,brl,
written + roffs,
na->compression_block_size
+ roffs)) {
done = TRUE;
written = to_write;
}
}
free(inbuf);
}
}
if (!done) {
/*
* if the compression block is not full, or
* if compression failed for whatever reason,
* write uncompressed
*/
/* check we are not overflowing current allocation */
if ((wpos + rounded)
> ((wrl->lcn + wrl->length)
<< vol->cluster_size_bits)) {
ntfs_log_error("writing on unallocated clusters\n");
errno = EIO;
} else {
written = ntfs_pwrite(vol->dev, wpos,
rounded, b);
if (written == rounded)
written = to_write;
}
}
}
return (written);
}
/*
* Close a file written compressed.
* This compresses the last partial compression block of the file.
* An empty runlist slot has to be reserved beforehand.
*
* Returns zero if closing is successful.
*/
int ntfs_compressed_close(ntfs_attr *na, runlist_element *wrl, s64 offs)
{
ntfs_volume *vol;
runlist_element *brl; /* entry containing the beginning of block */
int compression_length;
s64 written;
s64 to_read;
s64 roffs;
s64 got;
s64 start_vcn;
char *inbuf;
BOOL fail;
BOOL done;
vol = na->ni->vol;
compression_length = na->compression_block_clusters;
done = FALSE;
/*
* There generally is an uncompressed block at end of file,
* read the full block and compress it
*/
inbuf = (char*)ntfs_malloc(na->compression_block_size);
if (inbuf) {
start_vcn = (wrl->vcn + (offs >> vol->cluster_size_bits))
& -compression_length;
to_read = offs + ((wrl->vcn - start_vcn) << vol->cluster_size_bits);
brl = wrl;
fail = FALSE;
while (brl->vcn && (brl->vcn > start_vcn)) {
if (brl->lcn == (LCN)LCN_HOLE) {
ntfs_log_error("jump back over a hole when closing\n");
fail = TRUE;
errno = EIO;
}
brl--;
}
if (!fail) {
/* roffs can be an offset from another uncomp block */
roffs = (start_vcn - brl->vcn) << vol->cluster_size_bits;
if (to_read) {
got = read_clusters(vol, brl, roffs, to_read,
inbuf);
if (got == to_read) {
written = ntfs_comp_set(na, brl, roffs,
to_read, inbuf);
if ((written >= 0)
/* free the unused clusters */
&& !ntfs_compress_free(na,brl,
written + roffs,
na->compression_block_size + roffs)) {
done = TRUE;
} else
/* if compression failed, leave uncompressed */
if (written == -1)
done = TRUE;
}
} else
done = TRUE;
free(inbuf);
}
}
return (!done);
}
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