AuroraMiddleware/bzip2
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity
master
bzip2/compress.c
Mark Wielaard 812a898b76 Accept as many selectors as the file format allows. 
But ignore any larger than the theoretical maximum, BZ_MAX_SELECTORS.

The theoretical maximum number of selectors depends on the maximum
blocksize (900000 bytes) and the number of symbols (50) that can be
encoded with a different Huffman tree. BZ_MAX_SELECTORS is 18002.

But the bzip2 file format allows the number of selectors to be encoded
with 15 bits (because 18002 isn't a factor of 2 and doesn't fit in
14 bits). So the file format maximum is 32767 selectors.

Some bzip2 encoders might actually have written out more selectors
than the theoretical maximum because they rounded up the number of
selectors to some convenient factor of 8.

The extra 14766 selectors can never be validly used by the decompression
algorithm. So we can read them, but then discard them.

This is effectively what was done (by accident) before we added a
check for nSelectors to be at most BZ_MAX_SELECTORS to mitigate
CVE-2019-12900.

The extra selectors were written out after the array inside the
EState struct. But the struct has extra space allocated after the
selector arrays of 18060 bytes (which is larger than 14766).
All of which will be initialized later (so the overwrite of that
space with extra selector values would have been harmless).
2019-07-10 14:39:32 -05:00

673 lines
20 KiB
C
Raw Permalink Blame History

/*-------------------------------------------------------------*/
/*--- Compression machinery (not incl block sorting) ---*/
/*--- compress.c ---*/
/*-------------------------------------------------------------*/
/* ------------------------------------------------------------------
This file is part of bzip2/libbzip2, a program and library for
lossless, block-sorting data compression.
bzip2/libbzip2 version 1.0.6 of 6 September 2010
Copyright (C) 1996-2010 Julian Seward <jseward@acm.org>
Please read the WARNING, DISCLAIMER and PATENTS sections in the
README file.
This program is released under the terms of the license contained
in the file LICENSE.
------------------------------------------------------------------ */
/* CHANGES
0.9.0 -- original version.
0.9.0a/b -- no changes in this file.
0.9.0c -- changed setting of nGroups in sendMTFValues()
so as to do a bit better on small files
*/
#include "bzlib_private.h"
/*---------------------------------------------------*/
/*--- Bit stream I/O ---*/
/*---------------------------------------------------*/
/*---------------------------------------------------*/
void BZ2_bsInitWrite ( EState* s )
{
s->bsLive = 0;
s->bsBuff = 0;
}
/*---------------------------------------------------*/
static
void bsFinishWrite ( EState* s )
{
while (s->bsLive > 0) {
s->zbits[s->numZ] = (UChar)(s->bsBuff >> 24);
s->numZ++;
s->bsBuff <<= 8;
s->bsLive -= 8;
}
}
/*---------------------------------------------------*/
#define bsNEEDW(nz) \
{ \
while (s->bsLive >= 8) { \
s->zbits[s->numZ] \
= (UChar)(s->bsBuff >> 24); \
s->numZ++; \
s->bsBuff <<= 8; \
s->bsLive -= 8; \
} \
}
/*---------------------------------------------------*/
static
__inline__
void bsW ( EState* s, Int32 n, UInt32 v )
{
bsNEEDW ( n );
s->bsBuff |= (v << (32 - s->bsLive - n));
s->bsLive += n;
}
/*---------------------------------------------------*/
static
void bsPutUInt32 ( EState* s, UInt32 u )
{
bsW ( s, 8, (u >> 24) & 0xffL );
bsW ( s, 8, (u >> 16) & 0xffL );
bsW ( s, 8, (u >> 8) & 0xffL );
bsW ( s, 8, u & 0xffL );
}
/*---------------------------------------------------*/
static
void bsPutUChar ( EState* s, UChar c )
{
bsW( s, 8, (UInt32)c );
}
/*---------------------------------------------------*/
/*--- The back end proper ---*/
/*---------------------------------------------------*/
/*---------------------------------------------------*/
static
void makeMaps_e ( EState* s )
{
Int32 i;
s->nInUse = 0;
for (i = 0; i < 256; i++)
if (s->inUse[i]) {
s->unseqToSeq[i] = s->nInUse;
s->nInUse++;
}
}
/*---------------------------------------------------*/
static
void generateMTFValues ( EState* s )
{
UChar yy[256];
Int32 i, j;
Int32 zPend;
Int32 wr;
Int32 EOB;
/*
After sorting (eg, here),
s->arr1 [ 0 .. s->nblock-1 ] holds sorted order,
and
((UChar*)s->arr2) [ 0 .. s->nblock-1 ]
holds the original block data.
The first thing to do is generate the MTF values,
and put them in
((UInt16*)s->arr1) [ 0 .. s->nblock-1 ].
Because there are strictly fewer or equal MTF values
than block values, ptr values in this area are overwritten
with MTF values only when they are no longer needed.
The final compressed bitstream is generated into the
area starting at
(UChar*) (&((UChar*)s->arr2)[s->nblock])
These storage aliases are set up in bzCompressInit(),
except for the last one, which is arranged in
compressBlock().
*/
UInt32* ptr = s->ptr;
UChar* block = s->block;
UInt16* mtfv = s->mtfv;
makeMaps_e ( s );
EOB = s->nInUse+1;
for (i = 0; i <= EOB; i++) s->mtfFreq[i] = 0;
wr = 0;
zPend = 0;
for (i = 0; i < s->nInUse; i++) yy[i] = (UChar) i;
for (i = 0; i < s->nblock; i++) {
UChar ll_i;
AssertD ( wr <= i, "generateMTFValues(1)" );
j = ptr[i]-1; if (j < 0) j += s->nblock;
ll_i = s->unseqToSeq[block[j]];
AssertD ( ll_i < s->nInUse, "generateMTFValues(2a)" );
if (yy[0] == ll_i) {
zPend++;
} else {
if (zPend > 0) {
zPend--;
while (True) {
if (zPend & 1) {
mtfv[wr] = BZ_RUNB; wr++;
s->mtfFreq[BZ_RUNB]++;
} else {
mtfv[wr] = BZ_RUNA; wr++;
s->mtfFreq[BZ_RUNA]++;
}
if (zPend < 2) break;
zPend = (zPend - 2) / 2;
};
zPend = 0;
}
{
register UChar rtmp;
register UChar* ryy_j;
register UChar rll_i;
rtmp = yy[1];
yy[1] = yy[0];
ryy_j = &(yy[1]);
rll_i = ll_i;
while ( rll_i != rtmp ) {
register UChar rtmp2;
ryy_j++;
rtmp2 = rtmp;
rtmp = *ryy_j;
*ryy_j = rtmp2;
};
yy[0] = rtmp;
j = ryy_j - &(yy[0]);
mtfv[wr] = j+1; wr++; s->mtfFreq[j+1]++;
}
}
}
if (zPend > 0) {
zPend--;
while (True) {
if (zPend & 1) {
mtfv[wr] = BZ_RUNB; wr++;
s->mtfFreq[BZ_RUNB]++;
} else {
mtfv[wr] = BZ_RUNA; wr++;
s->mtfFreq[BZ_RUNA]++;
}
if (zPend < 2) break;
zPend = (zPend - 2) / 2;
};
zPend = 0;
}
mtfv[wr] = EOB; wr++; s->mtfFreq[EOB]++;
s->nMTF = wr;
}
/*---------------------------------------------------*/
#define BZ_LESSER_ICOST 0
#define BZ_GREATER_ICOST 15
static
void sendMTFValues ( EState* s )
{
Int32 v, t, i, j, gs, ge, totc, bt, bc, iter;
Int32 nSelectors, alphaSize, minLen, maxLen, selCtr;
Int32 nGroups, nBytes;
/*--
UChar len [BZ_N_GROUPS][BZ_MAX_ALPHA_SIZE];
is a global since the decoder also needs it.
Int32 code[BZ_N_GROUPS][BZ_MAX_ALPHA_SIZE];
Int32 rfreq[BZ_N_GROUPS][BZ_MAX_ALPHA_SIZE];
are also globals only used in this proc.
Made global to keep stack frame size small.
--*/
UInt16 cost[BZ_N_GROUPS];
Int32 fave[BZ_N_GROUPS];
UInt16* mtfv = s->mtfv;
if (s->verbosity >= 3)
VPrintf3( " %d in block, %d after MTF & 1-2 coding, "
"%d+2 syms in use\n",
s->nblock, s->nMTF, s->nInUse );
alphaSize = s->nInUse+2;
for (t = 0; t < BZ_N_GROUPS; t++)
for (v = 0; v < alphaSize; v++)
s->len[t][v] = BZ_GREATER_ICOST;
/*--- Decide how many coding tables to use ---*/
AssertH ( s->nMTF > 0, 3001 );
if (s->nMTF < 200) nGroups = 2; else
if (s->nMTF < 600) nGroups = 3; else
if (s->nMTF < 1200) nGroups = 4; else
if (s->nMTF < 2400) nGroups = 5; else
nGroups = 6;
/*--- Generate an initial set of coding tables ---*/
{
Int32 nPart, remF, tFreq, aFreq;
nPart = nGroups;
remF = s->nMTF;
gs = 0;
while (nPart > 0) {
tFreq = remF / nPart;
ge = gs-1;
aFreq = 0;
while (aFreq < tFreq && ge < alphaSize-1) {
ge++;
aFreq += s->mtfFreq[ge];
}
if (ge > gs
&& nPart != nGroups && nPart != 1
&& ((nGroups-nPart) % 2 == 1)) {
aFreq -= s->mtfFreq[ge];
ge--;
}
if (s->verbosity >= 3)
VPrintf5( " initial group %d, [%d .. %d], "
"has %d syms (%4.1f%%)\n",
nPart, gs, ge, aFreq,
(100.0 * (float)aFreq) / (float)(s->nMTF) );
for (v = 0; v < alphaSize; v++)
if (v >= gs && v <= ge)
s->len[nPart-1][v] = BZ_LESSER_ICOST; else
s->len[nPart-1][v] = BZ_GREATER_ICOST;
nPart--;
gs = ge+1;
remF -= aFreq;
}
}
/*---
Iterate up to BZ_N_ITERS times to improve the tables.
---*/
for (iter = 0; iter < BZ_N_ITERS; iter++) {
for (t = 0; t < nGroups; t++) fave[t] = 0;
for (t = 0; t < nGroups; t++)
for (v = 0; v < alphaSize; v++)
s->rfreq[t][v] = 0;
/*---
Set up an auxiliary length table which is used to fast-track
the common case (nGroups == 6).
---*/
if (nGroups == 6) {
for (v = 0; v < alphaSize; v++) {
s->len_pack[v][0] = (s->len[1][v] << 16) | s->len[0][v];
s->len_pack[v][1] = (s->len[3][v] << 16) | s->len[2][v];
s->len_pack[v][2] = (s->len[5][v] << 16) | s->len[4][v];
}
}
nSelectors = 0;
totc = 0;
gs = 0;
while (True) {
/*--- Set group start & end marks. --*/
if (gs >= s->nMTF) break;
ge = gs + BZ_G_SIZE - 1;
if (ge >= s->nMTF) ge = s->nMTF-1;
/*--
Calculate the cost of this group as coded
by each of the coding tables.
--*/
for (t = 0; t < nGroups; t++) cost[t] = 0;
if (nGroups == 6 && 50 == ge-gs+1) {
/*--- fast track the common case ---*/
register UInt32 cost01, cost23, cost45;
register UInt16 icv;
cost01 = cost23 = cost45 = 0;
# define BZ_ITER(nn) \
icv = mtfv[gs+(nn)]; \
cost01 += s->len_pack[icv][0]; \
cost23 += s->len_pack[icv][1]; \
cost45 += s->len_pack[icv][2]; \
BZ_ITER(0); BZ_ITER(1); BZ_ITER(2); BZ_ITER(3); BZ_ITER(4);
BZ_ITER(5); BZ_ITER(6); BZ_ITER(7); BZ_ITER(8); BZ_ITER(9);
BZ_ITER(10); BZ_ITER(11); BZ_ITER(12); BZ_ITER(13); BZ_ITER(14);
BZ_ITER(15); BZ_ITER(16); BZ_ITER(17); BZ_ITER(18); BZ_ITER(19);
BZ_ITER(20); BZ_ITER(21); BZ_ITER(22); BZ_ITER(23); BZ_ITER(24);
BZ_ITER(25); BZ_ITER(26); BZ_ITER(27); BZ_ITER(28); BZ_ITER(29);
BZ_ITER(30); BZ_ITER(31); BZ_ITER(32); BZ_ITER(33); BZ_ITER(34);
BZ_ITER(35); BZ_ITER(36); BZ_ITER(37); BZ_ITER(38); BZ_ITER(39);
BZ_ITER(40); BZ_ITER(41); BZ_ITER(42); BZ_ITER(43); BZ_ITER(44);
BZ_ITER(45); BZ_ITER(46); BZ_ITER(47); BZ_ITER(48); BZ_ITER(49);
# undef BZ_ITER
cost[0] = cost01 & 0xffff; cost[1] = cost01 >> 16;
cost[2] = cost23 & 0xffff; cost[3] = cost23 >> 16;
cost[4] = cost45 & 0xffff; cost[5] = cost45 >> 16;
} else {
/*--- slow version which correctly handles all situations ---*/
for (i = gs; i <= ge; i++) {
UInt16 icv = mtfv[i];
for (t = 0; t < nGroups; t++) cost[t] += s->len[t][icv];
}
}
/*--
Find the coding table which is best for this group,
and record its identity in the selector table.
--*/
bc = 999999999; bt = -1;
for (t = 0; t < nGroups; t++)
if (cost[t] < bc) { bc = cost[t]; bt = t; };
totc += bc;
fave[bt]++;
s->selector[nSelectors] = bt;
nSelectors++;
/*--
Increment the symbol frequencies for the selected table.
--*/
if (nGroups == 6 && 50 == ge-gs+1) {
/*--- fast track the common case ---*/
# define BZ_ITUR(nn) s->rfreq[bt][ mtfv[gs+(nn)] ]++
BZ_ITUR(0); BZ_ITUR(1); BZ_ITUR(2); BZ_ITUR(3); BZ_ITUR(4);
BZ_ITUR(5); BZ_ITUR(6); BZ_ITUR(7); BZ_ITUR(8); BZ_ITUR(9);
BZ_ITUR(10); BZ_ITUR(11); BZ_ITUR(12); BZ_ITUR(13); BZ_ITUR(14);
BZ_ITUR(15); BZ_ITUR(16); BZ_ITUR(17); BZ_ITUR(18); BZ_ITUR(19);
BZ_ITUR(20); BZ_ITUR(21); BZ_ITUR(22); BZ_ITUR(23); BZ_ITUR(24);
BZ_ITUR(25); BZ_ITUR(26); BZ_ITUR(27); BZ_ITUR(28); BZ_ITUR(29);
BZ_ITUR(30); BZ_ITUR(31); BZ_ITUR(32); BZ_ITUR(33); BZ_ITUR(34);
BZ_ITUR(35); BZ_ITUR(36); BZ_ITUR(37); BZ_ITUR(38); BZ_ITUR(39);
BZ_ITUR(40); BZ_ITUR(41); BZ_ITUR(42); BZ_ITUR(43); BZ_ITUR(44);
BZ_ITUR(45); BZ_ITUR(46); BZ_ITUR(47); BZ_ITUR(48); BZ_ITUR(49);
# undef BZ_ITUR
} else {
/*--- slow version which correctly handles all situations ---*/
for (i = gs; i <= ge; i++)
s->rfreq[bt][ mtfv[i] ]++;
}
gs = ge+1;
}
if (s->verbosity >= 3) {
VPrintf2 ( " pass %d: size is %d, grp uses are ",
iter+1, totc/8 );
for (t = 0; t < nGroups; t++)
VPrintf1 ( "%d ", fave[t] );
VPrintf0 ( "\n" );
}
/*--
Recompute the tables based on the accumulated frequencies.
--*/
/* maxLen was changed from 20 to 17 in bzip2-1.0.3. See
comment in huffman.c for details. */
for (t = 0; t < nGroups; t++)
BZ2_hbMakeCodeLengths ( &(s->len[t][0]), &(s->rfreq[t][0]),
alphaSize, 17 /*20*/ );
}
AssertH( nGroups < 8, 3002 );
AssertH( nSelectors < 32768 &&
nSelectors <= BZ_MAX_SELECTORS,
3003 );
/*--- Compute MTF values for the selectors. ---*/
{
UChar pos[BZ_N_GROUPS], ll_i, tmp2, tmp;
for (i = 0; i < nGroups; i++) pos[i] = i;
for (i = 0; i < nSelectors; i++) {
ll_i = s->selector[i];
j = 0;
tmp = pos[j];
while ( ll_i != tmp ) {
j++;
tmp2 = tmp;
tmp = pos[j];
pos[j] = tmp2;
};
pos[0] = tmp;
s->selectorMtf[i] = j;
}
};
/*--- Assign actual codes for the tables. --*/
for (t = 0; t < nGroups; t++) {
minLen = 32;
maxLen = 0;
for (i = 0; i < alphaSize; i++) {
if (s->len[t][i] > maxLen) maxLen = s->len[t][i];
if (s->len[t][i] < minLen) minLen = s->len[t][i];
}
AssertH ( !(maxLen > 17 /*20*/ ), 3004 );
AssertH ( !(minLen < 1), 3005 );
BZ2_hbAssignCodes ( &(s->code[t][0]), &(s->len[t][0]),
minLen, maxLen, alphaSize );
}
/*--- Transmit the mapping table. ---*/
{
Bool inUse16[16];
for (i = 0; i < 16; i++) {
inUse16[i] = False;
for (j = 0; j < 16; j++)
if (s->inUse[i * 16 + j]) inUse16[i] = True;
}
nBytes = s->numZ;
for (i = 0; i < 16; i++)
if (inUse16[i]) bsW(s,1,1); else bsW(s,1,0);
for (i = 0; i < 16; i++)
if (inUse16[i])
for (j = 0; j < 16; j++) {
if (s->inUse[i * 16 + j]) bsW(s,1,1); else bsW(s,1,0);
}
if (s->verbosity >= 3)
VPrintf1( " bytes: mapping %d, ", s->numZ-nBytes );
}
/*--- Now the selectors. ---*/
nBytes = s->numZ;
bsW ( s, 3, nGroups );
bsW ( s, 15, nSelectors );
for (i = 0; i < nSelectors; i++) {
for (j = 0; j < s->selectorMtf[i]; j++) bsW(s,1,1);
bsW(s,1,0);
}
if (s->verbosity >= 3)
VPrintf1( "selectors %d, ", s->numZ-nBytes );
/*--- Now the coding tables. ---*/
nBytes = s->numZ;
for (t = 0; t < nGroups; t++) {
Int32 curr = s->len[t][0];
bsW ( s, 5, curr );
for (i = 0; i < alphaSize; i++) {
while (curr < s->len[t][i]) { bsW(s,2,2); curr++; /* 10 */ };
while (curr > s->len[t][i]) { bsW(s,2,3); curr--; /* 11 */ };
bsW ( s, 1, 0 );
}
}
if (s->verbosity >= 3)
VPrintf1 ( "code lengths %d, ", s->numZ-nBytes );
/*--- And finally, the block data proper ---*/
nBytes = s->numZ;
selCtr = 0;
gs = 0;
while (True) {
if (gs >= s->nMTF) break;
ge = gs + BZ_G_SIZE - 1;
if (ge >= s->nMTF) ge = s->nMTF-1;
AssertH ( s->selector[selCtr] < nGroups, 3006 );
if (nGroups == 6 && 50 == ge-gs+1) {
/*--- fast track the common case ---*/
UInt16 mtfv_i;
UChar* s_len_sel_selCtr
= &(s->len[s->selector[selCtr]][0]);
Int32* s_code_sel_selCtr
= &(s->code[s->selector[selCtr]][0]);
# define BZ_ITAH(nn) \
mtfv_i = mtfv[gs+(nn)]; \
bsW ( s, \
s_len_sel_selCtr[mtfv_i], \
s_code_sel_selCtr[mtfv_i] )
BZ_ITAH(0); BZ_ITAH(1); BZ_ITAH(2); BZ_ITAH(3); BZ_ITAH(4);
BZ_ITAH(5); BZ_ITAH(6); BZ_ITAH(7); BZ_ITAH(8); BZ_ITAH(9);
BZ_ITAH(10); BZ_ITAH(11); BZ_ITAH(12); BZ_ITAH(13); BZ_ITAH(14);
BZ_ITAH(15); BZ_ITAH(16); BZ_ITAH(17); BZ_ITAH(18); BZ_ITAH(19);
BZ_ITAH(20); BZ_ITAH(21); BZ_ITAH(22); BZ_ITAH(23); BZ_ITAH(24);
BZ_ITAH(25); BZ_ITAH(26); BZ_ITAH(27); BZ_ITAH(28); BZ_ITAH(29);
BZ_ITAH(30); BZ_ITAH(31); BZ_ITAH(32); BZ_ITAH(33); BZ_ITAH(34);
BZ_ITAH(35); BZ_ITAH(36); BZ_ITAH(37); BZ_ITAH(38); BZ_ITAH(39);
BZ_ITAH(40); BZ_ITAH(41); BZ_ITAH(42); BZ_ITAH(43); BZ_ITAH(44);
BZ_ITAH(45); BZ_ITAH(46); BZ_ITAH(47); BZ_ITAH(48); BZ_ITAH(49);
# undef BZ_ITAH
} else {
/*--- slow version which correctly handles all situations ---*/
for (i = gs; i <= ge; i++) {
bsW ( s,
s->len [s->selector[selCtr]] [mtfv[i]],
s->code [s->selector[selCtr]] [mtfv[i]] );
}
}
gs = ge+1;
selCtr++;
}
AssertH( selCtr == nSelectors, 3007 );
if (s->verbosity >= 3)
VPrintf1( "codes %d\n", s->numZ-nBytes );
}
/*---------------------------------------------------*/
void BZ2_compressBlock ( EState* s, Bool is_last_block )
{
if (s->nblock > 0) {
BZ_FINALISE_CRC ( s->blockCRC );
s->combinedCRC = (s->combinedCRC << 1) | (s->combinedCRC >> 31);
s->combinedCRC ^= s->blockCRC;
if (s->blockNo > 1) s->numZ = 0;
if (s->verbosity >= 2)
VPrintf4( " block %d: crc = 0x%08x, "
"combined CRC = 0x%08x, size = %d\n",
s->blockNo, s->blockCRC, s->combinedCRC, s->nblock );
BZ2_blockSort ( s );
}
s->zbits = (UChar*) (&((UChar*)s->arr2)[s->nblock]);
/*-- If this is the first block, create the stream header. --*/
if (s->blockNo == 1) {
BZ2_bsInitWrite ( s );
bsPutUChar ( s, BZ_HDR_B );
bsPutUChar ( s, BZ_HDR_Z );
bsPutUChar ( s, BZ_HDR_h );
bsPutUChar ( s, (UChar)(BZ_HDR_0 + s->blockSize100k) );
}
if (s->nblock > 0) {
bsPutUChar ( s, 0x31 ); bsPutUChar ( s, 0x41 );
bsPutUChar ( s, 0x59 ); bsPutUChar ( s, 0x26 );
bsPutUChar ( s, 0x53 ); bsPutUChar ( s, 0x59 );
/*-- Now the block's CRC, so it is in a known place. --*/
bsPutUInt32 ( s, s->blockCRC );
/*--
Now a single bit indicating (non-)randomisation.
As of version 0.9.5, we use a better sorting algorithm
which makes randomisation unnecessary. So always set
the randomised bit to 'no'. Of course, the decoder
still needs to be able to handle randomised blocks
so as to maintain backwards compatibility with
older versions of bzip2.
--*/
bsW(s,1,0);
bsW ( s, 24, s->origPtr );
generateMTFValues ( s );
sendMTFValues ( s );
}
/*-- If this is the last block, add the stream trailer. --*/
if (is_last_block) {
bsPutUChar ( s, 0x17 ); bsPutUChar ( s, 0x72 );
bsPutUChar ( s, 0x45 ); bsPutUChar ( s, 0x38 );
bsPutUChar ( s, 0x50 ); bsPutUChar ( s, 0x90 );
bsPutUInt32 ( s, s->combinedCRC );
if (s->verbosity >= 2)
VPrintf1( " final combined CRC = 0x%08x\n ", s->combinedCRC );
bsFinishWrite ( s );
}
}
/*-------------------------------------------------------------*/
/*--- end compress.c ---*/
/*-------------------------------------------------------------*/
Reference in New Issue View Git Blame Copy Permalink