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Another bzip2 update and speedup from Manuel Novoa III, with some

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additional changes (primarily lots of comments) from Rob Landley.
This commit is contained in:
Eric Andersen 2003-10-23 06:52:01 +00:00
parent 2053a8c747
commit 5fa4db29f7
1 changed files with 268 additions and 224 deletions
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482
archival/libunarchive/decompress_bunzip2.c
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@ -10,6 +10,36 @@
LGPL (http://www.gnu.org/copyleft/lgpl.html LGPL (http://www.gnu.org/copyleft/lgpl.html
*/ */
/*
Size and speed optimizations by Manuel Novoa III (mjn3@codepoet.org).
More efficient reading of huffman codes, a streamlined read_bunzip()
function, and various other tweaks. In (limited) tests, approximately
20% faster than bzcat on x86 and about 10% faster on arm.
Note that about 2/3 of the time is spent in read_unzip() reversing
the Burrows-Wheeler transformation. Much of that time is delay
resulting from cache misses.
I would ask that anyone benefiting from this work, especially those
using it in commercial products, consider making a donation to my local
non-profit hospice organization in the name of the woman I loved, who
passed away Feb. 12, 2003.
In memory of Toni W. Hagan
Hospice of Acadiana, Inc.
2600 Johnston St., Suite 200
Lafayette, LA 70503-3240
Phone (337) 232-1234 or 1-800-738-2226
Fax (337) 232-1297
http://www.hospiceacadiana.com/
Manuel
*/
#include <setjmp.h> #include <setjmp.h>
#include <stdio.h> #include <stdio.h>
#include <stdlib.h> #include <stdlib.h>
@ -38,39 +68,31 @@
/* Other housekeeping constants */ /* Other housekeeping constants */
#define IOBUF_SIZE 4096 #define IOBUF_SIZE 4096
static char * const bunzip_errors[]={NULL,"Bad file checksum","Not bzip data",
"Unexpected input EOF","Unexpected output EOF","Data error",
"Out of memory","Obsolete (pre 0.9.5) bzip format not supported."};
/* This is what we know about each huffman coding group */ /* This is what we know about each huffman coding group */
struct group_data { struct group_data {
/* We have an extra slot at the end of limit[] for a sentinal value. */ /* We have an extra slot at the end of limit[] for a sentinal value. */
int limit[MAX_HUFCODE_BITS+1],base[MAX_HUFCODE_BITS],permute[MAX_SYMBOLS]; int limit[MAX_HUFCODE_BITS+1],base[MAX_HUFCODE_BITS],permute[MAX_SYMBOLS];
char minLen, maxLen; int minLen, maxLen;
}; };
/* Structure holding all the housekeeping data, including IO buffers and /* Structure holding all the housekeeping data, including IO buffers and
memory that persists between calls to bunzip */ memory that persists between calls to bunzip */
typedef struct { typedef struct {
/* For I/O error handling */ /* State for interrupting output loop */
jmp_buf jmpbuf; int writeCopies,writePos,writeRunCountdown,writeCount,writeCurrent;
/* Input stream, input buffer, input bit buffer */ /* I/O tracking data (file handles, buffers, positions, etc.) */
int in_fd,inbufCount,inbufPos; int in_fd,out_fd,inbufCount,inbufPos /*,outbufPos*/;
unsigned char *inbuf; unsigned char *inbuf /*,*outbuf*/;
unsigned int inbufBitCount, inbufBits; unsigned int inbufBitCount, inbufBits;
/* Output buffer */
char outbuf[IOBUF_SIZE];
int outbufPos;
/* The CRC values stored in the block header and calculated from the data */ /* The CRC values stored in the block header and calculated from the data */
unsigned int crc32Table[256],headerCRC, dataCRC, totalCRC; unsigned int crc32Table[256],headerCRC, totalCRC, writeCRC;
/* Intermediate buffer and its size (in bytes) */ /* Intermediate buffer and its size (in bytes) */
unsigned int *dbuf, dbufSize; unsigned int *dbuf, dbufSize;
/* State for interrupting output loop */
int writePos,writeRun,writeCount,writeCurrent;
/* These things are a bit too big to go on the stack */ /* These things are a bit too big to go on the stack */
unsigned char selectors[32768]; /* nSelectors=15 bits */ unsigned char selectors[32768]; /* nSelectors=15 bits */
struct group_data groups[MAX_GROUPS]; /* huffman coding tables */ struct group_data groups[MAX_GROUPS]; /* huffman coding tables */
/* For I/O error handling */
jmp_buf jmpbuf;
} bunzip_data; } bunzip_data;
/* Return the next nnn bits of input. All reads from the compressed input /* Return the next nnn bits of input. All reads from the compressed input
@ -106,39 +128,29 @@ static unsigned int get_bits(bunzip_data *bd, char bits_wanted)
return bits; return bits;
} }
/* At certain times, it pays to have an optimized inline version of /* Unpacks the next block and sets up for the inverse burrows-wheeler step. */
* get_bits() which gets a single bit. */
#define GET_A_BIT(bd) \
((bd->inbufBitCount > 0) \
? ((unsigned int)(((bd)->inbufBits >> --(bd)->inbufBitCount) & 1)) \
: get_bits((bd), 1))
static int get_next_block(bunzip_data *bd)
/* Decompress a block of text to into intermediate buffer */
extern int read_bunzip_data(bunzip_data *bd)
{ {
struct group_data *hufGroup; struct group_data *hufGroup;
int dbufCount,nextSym,dbufSize,origPtr,groupCount,*base,*limit,selector, int dbufCount,nextSym,dbufSize,groupCount,*base,*limit,selector,
i,j,k,t,runPos,symCount,symTotal,nSelectors,byteCount[256]; i,j,k,t,runPos,symCount,symTotal,nSelectors,byteCount[256];
unsigned char uc, symToByte[256], mtfSymbol[256], *selectors; unsigned char uc, symToByte[256], mtfSymbol[256], *selectors;
unsigned int *dbuf; unsigned int *dbuf,origPtr;
/* Read in header signature (borrowing mtfSymbol for temp space). */
for(i=0;i<6;i++) mtfSymbol[i]=get_bits(bd,8);
mtfSymbol[6]=0;
/* Read CRC (which is stored big endian). */
bd->headerCRC=get_bits(bd,32);
/* Is this the last block (with CRC for file)? */
if(!strcmp(mtfSymbol,"\x17\x72\x45\x38\x50\x90"))
return RETVAL_LAST_BLOCK;
/* If it's not a valid data block, barf. */
if(strcmp(mtfSymbol,"\x31\x41\x59\x26\x53\x59"))
return RETVAL_NOT_BZIP_DATA;
dbuf=bd->dbuf; dbuf=bd->dbuf;
dbufSize=bd->dbufSize; dbufSize=bd->dbufSize;
selectors=bd->selectors; selectors=bd->selectors;
/* Reset longjmp I/O error handling */
i=setjmp(bd->jmpbuf);
if(i) return i;
/* Read in header signature and CRC, then validate signature.
(last block signature means CRC is for whole file, return now) */
i = get_bits(bd,24);
j = get_bits(bd,24);
bd->headerCRC=get_bits(bd,32);
if ((i == 0x177245) && (j == 0x385090)) return RETVAL_LAST_BLOCK;
if ((i != 0x314159) || (j != 0x265359)) return RETVAL_NOT_BZIP_DATA;
/* We can add support for blockRandomised if anybody complains. There was /* We can add support for blockRandomised if anybody complains. There was
some code for this in busybox 1.0.0-pre3, but nobody ever noticed that some code for this in busybox 1.0.0-pre3, but nobody ever noticed that
it didn't actually work. */ it didn't actually work. */
@ -150,10 +162,6 @@ extern int read_bunzip_data(bunzip_data *bd)
values were present. We make a translation table to convert the symbols values were present. We make a translation table to convert the symbols
back to the corresponding bytes. */ back to the corresponding bytes. */
t=get_bits(bd, 16); t=get_bits(bd, 16);
#if 0
/* I don't believe this is necessary. Rob? */
memset(symToByte,0,256);
#endif
symTotal=0; symTotal=0;
for (i=0;i<16;i++) { for (i=0;i<16;i++) {
if(t&(1<<(15-i))) { if(t&(1<<(15-i))) {
@ -167,7 +175,8 @@ extern int read_bunzip_data(bunzip_data *bd)
if (groupCount<2 || groupCount>MAX_GROUPS) return RETVAL_DATA_ERROR; if (groupCount<2 || groupCount>MAX_GROUPS) return RETVAL_DATA_ERROR;
/* nSelectors: Every GROUP_SIZE many symbols we select a new huffman coding /* nSelectors: Every GROUP_SIZE many symbols we select a new huffman coding
group. Read in the group selector list, which is stored as MTF encoded group. Read in the group selector list, which is stored as MTF encoded
bit runs. */ bit runs. (MTF=Move To Front, as each value is used it's moved to the
start of the list.) */
if(!(nSelectors=get_bits(bd, 15))) return RETVAL_DATA_ERROR; if(!(nSelectors=get_bits(bd, 15))) return RETVAL_DATA_ERROR;
for(i=0; i<groupCount; i++) mtfSymbol[i] = i; for(i=0; i<groupCount; i++) mtfSymbol[i] = i;
for(i=0; i<nSelectors; i++) { for(i=0; i<nSelectors; i++) {
@ -175,13 +184,7 @@ extern int read_bunzip_data(bunzip_data *bd)
for(j=0;get_bits(bd,1);j++) if (j>=groupCount) return RETVAL_DATA_ERROR; for(j=0;get_bits(bd,1);j++) if (j>=groupCount) return RETVAL_DATA_ERROR;
/* Decode MTF to get the next selector */ /* Decode MTF to get the next selector */
uc = mtfSymbol[j]; uc = mtfSymbol[j];
/* A very small amount of data to move, so memmove is overkill for(;j;j--) mtfSymbol[j] = mtfSymbol[j-1];
* and bigger at least in my tests. */
k = j;
while (k) {
mtfSymbol[k] = mtfSymbol[k-1];
--k;
}
mtfSymbol[0]=selectors[i]=uc; mtfSymbol[0]=selectors[i]=uc;
} }
/* Read the huffman coding tables for each group, which code for symTotal /* Read the huffman coding tables for each group, which code for symTotal
@ -190,16 +193,30 @@ extern int read_bunzip_data(bunzip_data *bd)
for (j=0; j<groupCount; j++) { for (j=0; j<groupCount; j++) {
unsigned char length[MAX_SYMBOLS],temp[MAX_HUFCODE_BITS+1]; unsigned char length[MAX_SYMBOLS],temp[MAX_HUFCODE_BITS+1];
int minLen, maxLen, pp; int minLen, maxLen, pp;
/* Read lengths */ /* Read huffman code lengths for each symbol. They're stored in
t=get_bits(bd, 5) - 1; /* This lets us avoid a test in the loop. */ a way similar to mtf; record a starting value for the first symbol,
and an offset from the previous value for everys symbol after that.
(Subtracting 1 before the loop and then adding it back at the end is
an optimization that makes the test inside the loop simpler: symbol
length 0 becomes negative, so an unsigned inequality catches it.) */
t=get_bits(bd, 5)-1;
for (i = 0; i < symCount; i++) { for (i = 0; i < symCount; i++) {
for(;;) { for(;;) {
if (((unsigned)t) > (MAX_HUFCODE_BITS-1)) return RETVAL_DATA_ERROR; if (((unsigned)t) > (MAX_HUFCODE_BITS-1))
if(!get_bits(bd, 1)) break; return RETVAL_DATA_ERROR;
/* We can avoid an if/else with a little arithmetic. */ /* If first bit is 0, stop. Else second bit indicates whether
t += (1 - 2*get_bits(bd, 1)); /* 0 -> t++ ; 1 -> t-- */ to increment or decrement the value. Optimization: grab 2
bits and unget the second if the first was 0. */
k = get_bits(bd,2);
if (k < 2) {
bd->inbufBitCount++;
break;
} }
length[i] = t + 1; /* Correct for the initial -1 adjustment. */ /* Add one if second bit 1, else subtract 1. Avoids if/else */
t+=(((k+1)&2)-1);
}
/* Correct for the initial -1, to get the final symbol length */
length[i]=t+1;
} }
/* Find largest and smallest lengths in this group */ /* Find largest and smallest lengths in this group */
minLen=maxLen=length[0]; minLen=maxLen=length[0];
@ -214,11 +231,8 @@ extern int read_bunzip_data(bunzip_data *bd)
* value of a huffman symbol of a given length when using permute[]. * value of a huffman symbol of a given length when using permute[].
* *
* limit[] indicates the largest numerical value a symbol with a given * limit[] indicates the largest numerical value a symbol with a given
* number of bits can have. It lets us know when to stop reading. * number of bits can have. This is how the huffman codes can vary in
* * length: each code with a value>limit[length] needs another bit.
* To use these, keep reading bits until value<=limit[bitcount] or
* you've read over 20 bits (error). Then the decoded symbol
* equals permute[hufcode_value-base[hufcode_bitcount]].
*/ */
hufGroup=bd->groups+j; hufGroup=bd->groups+j;
hufGroup->minLen = minLen; hufGroup->minLen = minLen;
@ -228,22 +242,29 @@ extern int read_bunzip_data(bunzip_data *bd)
entry. We do this again when using them (during symbol decoding).*/ entry. We do this again when using them (during symbol decoding).*/
base=hufGroup->base-1; base=hufGroup->base-1;
limit=hufGroup->limit-1; limit=hufGroup->limit-1;
/* Calculate permute[] */ /* Calculate permute[]. Concurently, initialize temp[] and limit[]. */
pp=0; pp=0;
for(i=minLen;i<=maxLen;i++) for(i=minLen;i<=maxLen;i++) {
temp[i]=limit[i]=0;
for(t=0;t<symCount;t++) for(t=0;t<symCount;t++)
if(length[t]==i) hufGroup->permute[pp++] = t; if(length[t]==i) hufGroup->permute[pp++] = t;
/* Count cumulative symbols coded for at each bit length */ }
for (i=minLen;i<=maxLen;i++) temp[i]=limit[i]=0; /* Count symbols coded for at each bit length */
for (i=0;i<symCount;i++) temp[length[i]]++; for (i=0;i<symCount;i++) temp[length[i]]++;
/* Calculate limit[] (the largest symbol-coding value at each bit /* Calculate limit[] (the largest symbol-coding value at each bit
* length, which is (previous limit<<1)+symbols at this level), and * length, which is (previous limit<<1)+symbols at this level), and
* base[] (number of symbols to ignore at each bit length, which is * base[] (number of symbols to ignore at each bit length, which is
* limit-cumulative count of symbols coded for already). */ * limit minus the cumulative count of symbols coded for already). */
pp=t=0; pp=t=0;
for (i=minLen; i<maxLen; i++) { for (i=minLen; i<maxLen; i++) {
pp+=temp[i]; pp+=temp[i];
limit[i]=pp-1; /* We read the largest possible symbol size and then unget bits
after determining how many we need, and those extra bits could
be set to anything. (They're noise from future symbols.) At
each level we're really only interested in the first few bits,
so here we set all the trailing to-be-ignored bits to 1 so they
don't affect the value>limit[length] comparison. */
limit[i]= (pp << (maxLen - i)) - 1;
pp<<=1; pp<<=1;
base[i+1]=pp-(t+=temp[i]); base[i+1]=pp-(t+=temp[i]);
} }
@ -255,10 +276,12 @@ extern int read_bunzip_data(bunzip_data *bd)
block's huffman coded symbols from the file and undo the huffman coding block's huffman coded symbols from the file and undo the huffman coding
and run length encoding, saving the result into dbuf[dbufCount++]=uc */ and run length encoding, saving the result into dbuf[dbufCount++]=uc */
/* Initialize symbol occurrence counters and symbol mtf table */ /* Initialize symbol occurrence counters and symbol Move To Front table */
memset(byteCount,0,256*sizeof(int)); for(i=0;i<256;i++) {
for(i=0;i<256;i++) mtfSymbol[i]=(unsigned char)i; byteCount[i] = 0;
/* Loop through compressed symbols */ mtfSymbol[i]=(unsigned char)i;
}
/* Loop through compressed symbols. */
runPos=dbufCount=symCount=selector=0; runPos=dbufCount=symCount=selector=0;
for(;;) { for(;;) {
/* Determine which huffman coding group to use. */ /* Determine which huffman coding group to use. */
@ -269,17 +292,41 @@ extern int read_bunzip_data(bunzip_data *bd)
base=hufGroup->base-1; base=hufGroup->base-1;
limit=hufGroup->limit-1; limit=hufGroup->limit-1;
} }
/* Read next huffman-coded symbol */ /* Read next huffman-coded symbol. */
i = hufGroup->minLen; /* Note: It is far cheaper to read maxLen bits and back up than it is
j=get_bits(bd, i); to read minLen bits and then an additional bit at a time, testing
while (j > limit[i]) { /* The sentinal allows us to avoid testing i. */ as we go. Because there is a trailing last block (with file CRC),
j = (j << 1) | GET_A_BIT(bd); there is no danger of the overread causing an unexpected EOF for a
++i; valid compressed file. As a further optimization, we do the read
inline (falling back to a call to get_bits if the buffer runs
dry). The following (up to got_huff_bits:) is equivalent to
j=get_bits(bd,hufGroup->maxLen);
*/
while (bd->inbufBitCount<hufGroup->maxLen) {
if(bd->inbufPos==bd->inbufCount) {
j = get_bits(bd,hufGroup->maxLen);
goto got_huff_bits;
} }
/* Huffman decode nextSym (with bounds checking) */ bd->inbufBits=(bd->inbufBits<<8)|bd->inbuf[bd->inbufPos++];
if ((i > hufGroup->maxLen) || (((unsigned)(j-=base[i])) >= MAX_SYMBOLS)) return RETVAL_DATA_ERROR; bd->inbufBitCount+=8;
};
bd->inbufBitCount-=hufGroup->maxLen;
j = (bd->inbufBits>>bd->inbufBitCount)&((1<<hufGroup->maxLen)-1);
got_huff_bits:
/* Figure how how many bits are in next symbol and unget extras */
i=hufGroup->minLen;
while(j>limit[i]) ++i;
bd->inbufBitCount += (hufGroup->maxLen - i);
/* Huffman decode value to get nextSym (with bounds checking) */
if ((i > hufGroup->maxLen)
|| (((unsigned)(j=(j>>(hufGroup->maxLen-i))-base[i]))
>= MAX_SYMBOLS))
return RETVAL_DATA_ERROR;
nextSym = hufGroup->permute[j]; nextSym = hufGroup->permute[j];
/* If this is a repeated run, loop collecting data */ /* We have now decoded the symbol, which indicates either a new literal
byte, or a repeated run of the most recent literal byte. First,
check if nextSym indicates a repeated run, and if so loop collecting
how many times to repeat the last literal. */
if (((unsigned)nextSym) <= SYMBOL_RUNB) { /* RUNA or RUNB */ if (((unsigned)nextSym) <= SYMBOL_RUNB) { /* RUNA or RUNB */
/* If this is the start of a new run, zero out counter */ /* If this is the start of a new run, zero out counter */
if(!runPos) { if(!runPos) {
@ -311,19 +358,20 @@ extern int read_bunzip_data(bunzip_data *bd)
} }
/* Is this the terminating symbol? */ /* Is this the terminating symbol? */
if(nextSym>symTotal) break; if(nextSym>symTotal) break;
/* At this point, the symbol we just decoded indicates a new literal /* At this point, nextSym indicates a new literal character. Subtract
character. Subtract one to get the position in the MTF array one to get the position in the MTF array at which this literal is
at which this literal is currently to be found. (Note that the currently to be found. (Note that the result can't be -1 or 0,
result can't be -1 or 0, because 0 and 1 are RUNA and RUNB. because 0 and 1 are RUNA and RUNB. But another instance of the
Another instance of the first symbol in the mtf array, position 0, first symbol in the mtf array, position 0, would have been handled
would have been handled as part of a run.) */ as part of a run above. Therefore 1 unused mtf position minus
2 non-literal nextSym values equals -1.) */
if(dbufCount>=dbufSize) return RETVAL_DATA_ERROR; if(dbufCount>=dbufSize) return RETVAL_DATA_ERROR;
i = nextSym - 1; i = nextSym - 1;
uc = mtfSymbol[i]; uc = mtfSymbol[i];
/* Since we typically expect to move only a small number of symbols, /* Adjust the MTF array. Since we typically expect to move only a
* and are bound by 256 in any case, using memmove here would * small number of symbols, and are bound by 256 in any case, using
* typically be slower due to function call overhead and other * memmove here would typically be bigger and slower due to function
* assorted setup costs. */ * call overhead and other assorted setup costs. */
do { do {
mtfSymbol[i] = mtfSymbol[i-1]; mtfSymbol[i] = mtfSymbol[i-1];
} while (--i); } while (--i);
@ -333,14 +381,12 @@ extern int read_bunzip_data(bunzip_data *bd)
byteCount[uc]++; byteCount[uc]++;
dbuf[dbufCount++] = (unsigned int)uc; dbuf[dbufCount++] = (unsigned int)uc;
} }
/* At this point, we've finished reading huffman-coded symbols and /* At this point, we've read all the huffman-coded symbols (and repeated
compressed runs from the input stream. There are dbufCount many of runs) for this block from the input stream, and decoded them into the
them in dbuf[]. Now undo the Burrows-Wheeler transform on dbuf. intermediate buffer. There are dbufCount many decoded bytes in dbuf[].
Now undo the Burrows-Wheeler transform on dbuf.
See http://dogma.net/markn/articles/bwt/bwt.htm See http://dogma.net/markn/articles/bwt/bwt.htm
*/ */
/* Now we know what dbufCount is, do a better sanity check on origPtr. */
if (((unsigned)origPtr)>=dbufCount) return RETVAL_DATA_ERROR;
/* Turn byteCount into cumulative occurrence counts of 0 to n-1. */ /* Turn byteCount into cumulative occurrence counts of 0 to n-1. */
j=0; j=0;
for(i=0;i<256;i++) { for(i=0;i<256;i++) {
@ -354,140 +400,133 @@ extern int read_bunzip_data(bunzip_data *bd)
dbuf[byteCount[uc]] |= (i << 8); dbuf[byteCount[uc]] |= (i << 8);
byteCount[uc]++; byteCount[uc]++;
} }
/* blockRandomised support would go here. */
/* Using i as position, j as previous character, t as current character,
and uc as run count */
bd->dataCRC = 0xffffffffL;
/* Decode first byte by hand to initialize "previous" byte. Note that it /* Decode first byte by hand to initialize "previous" byte. Note that it
doesn't get output, and if the first three characters are identical doesn't get output, and if the first three characters are identical
it doesn't qualify as a run (hence uc=255, which will either wrap it doesn't qualify as a run (hence writeRunCountdown=5). */
to 1 or get reset). */
if(dbufCount) { if(dbufCount) {
if(origPtr>=dbufCount) return RETVAL_DATA_ERROR;
bd->writePos=dbuf[origPtr]; bd->writePos=dbuf[origPtr];
bd->writeCurrent=(unsigned char)(bd->writePos&0xff); bd->writeCurrent=(unsigned char)(bd->writePos&0xff);
bd->writePos>>=8; bd->writePos>>=8;
bd->writeRun=-1; bd->writeRunCountdown=5;
} }
bd->writeCount=dbufCount; bd->writeCount=dbufCount;
return RETVAL_OK; return RETVAL_OK;
} }
/* Flush output buffer to disk */
extern void flush_bunzip_outbuf(bunzip_data *bd, int out_fd)
{
if(bd->outbufPos) {
if(write(out_fd, bd->outbuf, bd->outbufPos) != bd->outbufPos)
longjmp(bd->jmpbuf,RETVAL_UNEXPECTED_OUTPUT_EOF);
bd->outbufPos=0;
}
}
/* Undo burrows-wheeler transform on intermediate buffer to produce output. /* Undo burrows-wheeler transform on intermediate buffer to produce output.
If !len, write up to len bytes of data to buf. Otherwise write to out_fd. If start_bunzip was initialized with out_fd=-1, then up to len bytes of
Returns len ? bytes written : RETVAL_OK. Notice all errors negative #'s. */ data are written to outbuf. Return value is number of bytes written or
extern int write_bunzip_data(bunzip_data *bd, int out_fd, char *outbuf, int len) error (all errors are negative numbers). If out_fd!=-1, outbuf and len
{ are ignored, data is written to out_fd and return is RETVAL_OK or error.
unsigned int *dbuf=bd->dbuf; */
int count,pos,current, run,copies,outbyte,previous,gotcount=0;
extern int read_bunzip(bunzip_data *bd, char *outbuf, int len)
{
const unsigned int *dbuf;
int pos,current,previous,gotcount;
for(;;) {
/* If last read was short due to end of file, return last block now */ /* If last read was short due to end of file, return last block now */
if(bd->writeCount<0) return bd->writeCount; if(bd->writeCount<0) return bd->writeCount;
/* If we need to refill dbuf, do it. */
if(!bd->writeCount) { gotcount = 0;
int i=read_bunzip_data(bd); dbuf=bd->dbuf;
if(i) {
if(i==RETVAL_LAST_BLOCK) {
bd->writeCount=i;
return gotcount;
} else return i;
}
}
/* Loop generating output */
count=bd->writeCount;
pos=bd->writePos; pos=bd->writePos;
current=bd->writeCurrent; current=bd->writeCurrent;
run=bd->writeRun;
while(count) { /* We will always have pending decoded data to write into the output
/* If somebody (like busybox tar) wants a certain number of bytes of buffer unless this is the very first call (in which case we haven't
data from memory instead of written to a file, humor them */ huffman-decoded a block into the intermediate buffer yet). */
if(len && bd->outbufPos>=len) goto dataus_interruptus;
count--; if (bd->writeCopies) {
/* Inside the loop, writeCopies means extra copies (beyond 1) */
--bd->writeCopies;
/* Loop outputting bytes */
for(;;) {
/* If the output buffer is full, snapshot state and return */
if(gotcount >= len) {
bd->writePos=pos;
bd->writeCurrent=current;
bd->writeCopies++;
return len;
}
/* Write next byte into output buffer, updating CRC */
outbuf[gotcount++] = current;
bd->writeCRC=(((bd->writeCRC)<<8)
^bd->crc32Table[((bd->writeCRC)>>24)^current]);
/* Loop now if we're outputting multiple copies of this byte */
if (bd->writeCopies) {
--bd->writeCopies;
continue;
}
decode_next_byte:
if (!bd->writeCount--) break;
/* Follow sequence vector to undo Burrows-Wheeler transform */ /* Follow sequence vector to undo Burrows-Wheeler transform */
previous=current; previous=current;
pos=dbuf[pos]; pos=dbuf[pos];
current=pos&0xff; current=pos&0xff;
pos>>=8; pos>>=8;
/* Whenever we see 3 consecutive copies of the same byte, /* After 3 consecutive copies of the same byte, the 4th is a repeat
the 4th is a repeat count */ count. We count down from 4 instead
if(run++==3) { * of counting up because testing for non-zero is faster */
copies=current; if(--bd->writeRunCountdown) {
outbyte=previous; if(current!=previous) bd->writeRunCountdown=4;
current=-1;
} else { } else {
copies=1; /* We have a repeated run, this byte indicates the count */
outbyte=current; bd->writeCopies=current;
current=previous;
bd->writeRunCountdown=5;
/* Sometimes there are just 3 bytes (run length 0) */
if(!bd->writeCopies) goto decode_next_byte;
/* Subtract the 1 copy we'd output anyway to get extras */
--bd->writeCopies;
} }
/* Output bytes to buffer, flushing to file if necessary */
while(copies--) {
if(bd->outbufPos == IOBUF_SIZE) flush_bunzip_outbuf(bd,out_fd);
bd->outbuf[bd->outbufPos++] = outbyte;
bd->dataCRC = (bd->dataCRC << 8)
^ bd->crc32Table[(bd->dataCRC >> 24) ^ outbyte];
}
if(current!=previous) run=0;
} }
/* Decompression of this block completed successfully */ /* Decompression of this block completed successfully */
bd->dataCRC=~(bd->dataCRC); bd->writeCRC=~bd->writeCRC;
bd->totalCRC=((bd->totalCRC << 1) | (bd->totalCRC >> 31)) ^ bd->dataCRC; bd->totalCRC=((bd->totalCRC<<1) | (bd->totalCRC>>31)) ^ bd->writeCRC;
/* If this block had a CRC error, force file level CRC error. */ /* If this block had a CRC error, force file level CRC error. */
if(bd->dataCRC!=bd->headerCRC) { if(bd->writeCRC!=bd->headerCRC) {
bd->totalCRC=bd->headerCRC+1; bd->totalCRC=bd->headerCRC+1;
return RETVAL_LAST_BLOCK; return RETVAL_LAST_BLOCK;
} }
dataus_interruptus:
bd->writeCount=count;
if(len) {
gotcount+=bd->outbufPos;
memcpy(outbuf,bd->outbuf,len);
/* If we got enough data, checkpoint loop state and return */
if((len-=bd->outbufPos)<1) {
bd->outbufPos-=len;
if(bd->outbufPos)
memmove(bd->outbuf,bd->outbuf+len,bd->outbufPos);
bd->writePos=pos;
bd->writeCurrent=current;
bd->writeRun=run;
return gotcount;
}
}
}
} }
/* Allocate the structure, read file header. If !len, src_fd contains /* Refill the intermediate buffer by huffman-decoding next block of input */
filehandle to read from. Else inbuf contains data. */ /* (previous is just a convenient unused temp variable here) */
extern int start_bunzip(bunzip_data **bdp, int src_fd, char *inbuf, int len) previous=get_next_block(bd);
if(previous) {
bd->writeCount=previous;
return (previous!=RETVAL_LAST_BLOCK) ? previous : gotcount;
}
bd->writeCRC=0xffffffffUL;
pos=bd->writePos;
current=bd->writeCurrent;
goto decode_next_byte;
}
/* Allocate the structure, read file header. If in_fd==-1, inbuf must contain
a complete bunzip file (len bytes long). If in_fd!=-1, inbuf and len are
ignored, and data is read from file handle into temporary buffer. */
extern int start_bunzip(bunzip_data **bdp, int in_fd, char *inbuf, int len)
{ {
bunzip_data *bd; bunzip_data *bd;
unsigned int i,j,c; unsigned int i,j,c;
const unsigned int BZh0=(((unsigned int)'B')<<24)+(((unsigned int)'Z')<<16)
+(((unsigned int)'h')<<8)+(unsigned int)'0';
/* Figure out how much data to allocate */ /* Figure out how much data to allocate */
i=sizeof(bunzip_data); i=sizeof(bunzip_data);
if(!len) i+=IOBUF_SIZE; if(in_fd!=-1) i+=IOBUF_SIZE;
/* Allocate bunzip_data. Most fields initialize to zero. */ /* Allocate bunzip_data. Most fields initialize to zero. */
if(!(bd=*bdp=malloc(i))) return RETVAL_OUT_OF_MEMORY; if(!(bd=*bdp=malloc(i))) return RETVAL_OUT_OF_MEMORY;
memset(bd,0,sizeof(bunzip_data)); memset(bd,0,sizeof(bunzip_data));
if(len) { /* Setup input buffer */
if(-1==(bd->in_fd=in_fd)) {
bd->inbuf=inbuf; bd->inbuf=inbuf;
bd->inbufCount=len; bd->inbufCount=len;
bd->in_fd=-1; } else bd->inbuf=(unsigned char *)(bd+1);
} else {
bd->inbuf=(char *)(bd+1);
bd->in_fd=src_fd;
}
/* Init the CRC32 table (big endian) */ /* Init the CRC32 table (big endian) */
for(i=0;i<256;i++) { for(i=0;i<256;i++) {
c=i<<24; c=i<<24;
@ -498,55 +537,60 @@ extern int start_bunzip(bunzip_data **bdp, int src_fd, char *inbuf, int len)
/* Setup for I/O error handling via longjmp */ /* Setup for I/O error handling via longjmp */
i=setjmp(bd->jmpbuf); i=setjmp(bd->jmpbuf);
if(i) return i; if(i) return i;
/* Ensure that file starts with "BZh" */
for(i=0;i<3;i++) if(get_bits(bd,8)!="BZh"[i]) return RETVAL_NOT_BZIP_DATA; /* Ensure that file starts with "BZh['1'-'9']." */
/* Next byte ascii '1'-'9', indicates block size in units of 100k of i = get_bits(bd,32);
if (((unsigned int)(i-BZh0-1)) >= 9) return RETVAL_NOT_BZIP_DATA;
/* Fourth byte (ascii '1'-'9'), indicates block size in units of 100k of
uncompressed data. Allocate intermediate buffer for block. */ uncompressed data. Allocate intermediate buffer for block. */
i=get_bits(bd,8); bd->dbufSize=100000*(i-BZh0);
if (i<'1' || i>'9') return RETVAL_NOT_BZIP_DATA;
bd->dbufSize=100000*(i-'0');
if(!(bd->dbuf=malloc(bd->dbufSize * sizeof(int)))) if(!(bd->dbuf=malloc(bd->dbufSize * sizeof(int))))
return RETVAL_OUT_OF_MEMORY; return RETVAL_OUT_OF_MEMORY;
return RETVAL_OK; return RETVAL_OK;
} }
extern char *uncompressStream(int src_fd, int dst_fd) /* Example usage: decompress src_fd to dst_fd. (Stops at end of bzip data,
not end of file.) */
extern int uncompressStream(int src_fd, int dst_fd)
{ {
char *outbuf;
bunzip_data *bd; bunzip_data *bd;
int i; int i;
if(!(outbuf=malloc(IOBUF_SIZE))) return RETVAL_OUT_OF_MEMORY;
if(!(i=start_bunzip(&bd,src_fd,0,0))) { if(!(i=start_bunzip(&bd,src_fd,0,0))) {
i=write_bunzip_data(bd,dst_fd,0,0); for(;;) {
if(i==RETVAL_LAST_BLOCK && bd->headerCRC==bd->totalCRC) i=RETVAL_OK; if((i=read_bunzip(bd,outbuf,IOBUF_SIZE)) <= 0) break;
if(i!=write(dst_fd,outbuf,i)) {
i=RETVAL_UNEXPECTED_OUTPUT_EOF;
break;
} }
flush_bunzip_outbuf(bd,dst_fd); }
}
/* Check CRC and release memory */
if(i==RETVAL_LAST_BLOCK && bd->headerCRC==bd->totalCRC) i=RETVAL_OK;
if(bd->dbuf) free(bd->dbuf); if(bd->dbuf) free(bd->dbuf);
free(bd); free(bd);
return bunzip_errors[-i]; free(outbuf);
return i;
} }
/* This new version is not yet properly integrated with tar */ #ifdef TESTING
extern ssize_t read_bz2(int fd, void *buf, size_t count)
{
#warning FIXME
return(0);
}
extern void BZ2_bzReadOpen(int fd, void *unused, int nUnused) static char * const bunzip_errors[]={NULL,"Bad file checksum","Not bzip data",
{ "Unexpected input EOF","Unexpected output EOF","Data error",
#warning FIXME "Out of memory","Obsolete (pre 0.9.5) bzip format not supported."};
return;
}
extern void BZ2_bzReadClose(void)
{
#warning FIXME
}
#if 0
/* Dumb little test thing, decompress stdin to stdout */ /* Dumb little test thing, decompress stdin to stdout */
int main(int argc, char *argv[]) int main(int argc, char *argv[])
{ {
char *c=uncompressStream(0,1); int i=uncompressStream(0,1);
fprintf(stderr,"\n%s\n", c ? c : "Completed OK"); char c;
if(i) fprintf(stderr,"%s\n", bunzip_errors[-i]);
else if(read(0,&c,1)) fprintf(stderr,"Trailing garbage ignored\n");
return -i;
} }
#endif #endif