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 <stdio.h>
#include <stdlib.h>
/* Other housekeeping constants */
#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 */
struct group_data {
/* 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];
- char minLen, maxLen;
+ int minLen, maxLen;
};
/* Structure holding all the housekeeping data, including IO buffers and
memory that persists between calls to bunzip */
typedef struct {
- /* For I/O error handling */
- jmp_buf jmpbuf;
- /* Input stream, input buffer, input bit buffer */
- int in_fd,inbufCount,inbufPos;
- unsigned char *inbuf;
+ /* State for interrupting output loop */
+ int writeCopies,writePos,writeRunCountdown,writeCount,writeCurrent;
+ /* I/O tracking data (file handles, buffers, positions, etc.) */
+ int in_fd,out_fd,inbufCount,inbufPos /*,outbufPos*/;
+ unsigned char *inbuf /*,*outbuf*/;
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 */
- unsigned int crc32Table[256],headerCRC, dataCRC, totalCRC;
+ unsigned int crc32Table[256],headerCRC, totalCRC, writeCRC;
/* Intermediate buffer and its size (in bytes) */
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 */
unsigned char selectors[32768]; /* nSelectors=15 bits */
struct group_data groups[MAX_GROUPS]; /* huffman coding tables */
+ /* For I/O error handling */
+ jmp_buf jmpbuf;
} bunzip_data;
/* Return the next nnn bits of input. All reads from the compressed input
return bits;
}
-/* At certain times, it pays to have an optimized inline version of
- * 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))
-
-
-/* Decompress a block of text to into intermediate buffer */
+/* Unpacks the next block and sets up for the inverse burrows-wheeler step. */
-extern int read_bunzip_data(bunzip_data *bd)
+static int get_next_block(bunzip_data *bd)
{
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];
unsigned char uc, symToByte[256], mtfSymbol[256], *selectors;
- unsigned int *dbuf;
-
- /* 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;
+ unsigned int *dbuf,origPtr;
dbuf=bd->dbuf;
dbufSize=bd->dbufSize;
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
some code for this in busybox 1.0.0-pre3, but nobody ever noticed that
it didn't actually work. */
values were present. We make a translation table to convert the symbols
back to the corresponding bytes. */
t=get_bits(bd, 16);
-#if 0
- /* I don't believe this is necessary. Rob? */
- memset(symToByte,0,256);
-#endif
symTotal=0;
for (i=0;i<16;i++) {
if(t&(1<<(15-i))) {
if (groupCount<2 || groupCount>MAX_GROUPS) return RETVAL_DATA_ERROR;
/* 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
- 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;
for(i=0; i<groupCount; i++) mtfSymbol[i] = i;
for(i=0; i<nSelectors; i++) {
for(j=0;get_bits(bd,1);j++) if (j>=groupCount) return RETVAL_DATA_ERROR;
/* Decode MTF to get the next selector */
uc = mtfSymbol[j];
- /* A very small amount of data to move, so memmove is overkill
- * and bigger at least in my tests. */
- k = j;
- while (k) {
- mtfSymbol[k] = mtfSymbol[k-1];
- --k;
- }
+ for(;j;j--) mtfSymbol[j] = mtfSymbol[j-1];
mtfSymbol[0]=selectors[i]=uc;
}
/* Read the huffman coding tables for each group, which code for symTotal
for (j=0; j<groupCount; j++) {
unsigned char length[MAX_SYMBOLS],temp[MAX_HUFCODE_BITS+1];
int minLen, maxLen, pp;
- /* Read lengths */
- t=get_bits(bd, 5) - 1; /* This lets us avoid a test in the loop. */
+ /* Read huffman code lengths for each symbol. They're stored in
+ 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(;;) {
- if (((unsigned)t) > (MAX_HUFCODE_BITS-1)) return RETVAL_DATA_ERROR;
- if(!get_bits(bd, 1)) break;
- /* We can avoid an if/else with a little arithmetic. */
- t += (1 - 2*get_bits(bd, 1)); /* 0 -> t++ ; 1 -> t-- */
+ if (((unsigned)t) > (MAX_HUFCODE_BITS-1))
+ return RETVAL_DATA_ERROR;
+ /* If first bit is 0, stop. Else second bit indicates whether
+ 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;
+ }
+ /* Add one if second bit 1, else subtract 1. Avoids if/else */
+ t+=(((k+1)&2)-1);
}
- length[i] = t + 1; /* Correct for the initial -1 adjustment. */
+ /* Correct for the initial -1, to get the final symbol length */
+ length[i]=t+1;
}
/* Find largest and smallest lengths in this group */
minLen=maxLen=length[0];
* value of a huffman symbol of a given length when using permute[].
*
* limit[] indicates the largest numerical value a symbol with a given
- * number of bits can have. It lets us know when to stop reading.
- *
- * 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]].
+ * 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.
*/
hufGroup=bd->groups+j;
hufGroup->minLen = minLen;
entry. We do this again when using them (during symbol decoding).*/
base=hufGroup->base-1;
limit=hufGroup->limit-1;
- /* Calculate permute[] */
- pp = 0;
- for(i=minLen;i<=maxLen;i++)
+ /* Calculate permute[]. Concurently, initialize temp[] and limit[]. */
+ pp=0;
+ for(i=minLen;i<=maxLen;i++) {
+ temp[i]=limit[i]=0;
for(t=0;t<symCount;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]]++;
/* Calculate limit[] (the largest symbol-coding value at each bit
* length, which is (previous limit<<1)+symbols at this level), and
* 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;
for (i=minLen; i<maxLen; 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;
base[i+1]=pp-(t+=temp[i]);
}
block's huffman coded symbols from the file and undo the huffman coding
and run length encoding, saving the result into dbuf[dbufCount++]=uc */
- /* Initialize symbol occurrence counters and symbol mtf table */
- memset(byteCount,0,256*sizeof(int));
- for(i=0;i<256;i++) mtfSymbol[i]=(unsigned char)i;
- /* Loop through compressed symbols */
+ /* Initialize symbol occurrence counters and symbol Move To Front table */
+ for(i=0;i<256;i++) {
+ byteCount[i] = 0;
+ mtfSymbol[i]=(unsigned char)i;
+ }
+ /* Loop through compressed symbols. */
runPos=dbufCount=symCount=selector=0;
for(;;) {
/* Determine which huffman coding group to use. */
base=hufGroup->base-1;
limit=hufGroup->limit-1;
}
- /* Read next huffman-coded symbol */
- i = hufGroup->minLen;
- j=get_bits(bd, i);
- while (j > limit[i]) { /* The sentinal allows us to avoid testing i. */
- j = (j << 1) | GET_A_BIT(bd);
- ++i;
- }
- /* Huffman decode nextSym (with bounds checking) */
- if ((i > hufGroup->maxLen) || (((unsigned)(j-=base[i])) >= MAX_SYMBOLS)) return RETVAL_DATA_ERROR;
+ /* Read next huffman-coded symbol. */
+ /* Note: It is far cheaper to read maxLen bits and back up than it is
+ to read minLen bits and then an additional bit at a time, testing
+ as we go. Because there is a trailing last block (with file CRC),
+ there is no danger of the overread causing an unexpected EOF for a
+ 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;
+ }
+ bd->inbufBits=(bd->inbufBits<<8)|bd->inbuf[bd->inbufPos++];
+ 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];
- /* 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 this is the start of a new run, zero out counter */
if(!runPos) {
}
/* Is this the terminating symbol? */
if(nextSym>symTotal) break;
- /* At this point, the symbol we just decoded indicates a new literal
- character. Subtract one to get the position in the MTF array
- at which this literal is currently to be found. (Note that the
- result can't be -1 or 0, because 0 and 1 are RUNA and RUNB.
- Another instance of the first symbol in the mtf array, position 0,
- would have been handled as part of a run.) */
+ /* At this point, nextSym indicates a new literal character. Subtract
+ one to get the position in the MTF array at which this literal is
+ currently to be found. (Note that the result can't be -1 or 0,
+ because 0 and 1 are RUNA and RUNB. But another instance of the
+ first symbol in the mtf array, position 0, would have been handled
+ 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;
i = nextSym - 1;
uc = mtfSymbol[i];
- /* Since we typically expect to move only a small number of symbols,
- * and are bound by 256 in any case, using memmove here would
- * typically be slower due to function call overhead and other
- * assorted setup costs. */
+ /* Adjust the MTF array. Since we typically expect to move only a
+ * small number of symbols, and are bound by 256 in any case, using
+ * memmove here would typically be bigger and slower due to function
+ * call overhead and other assorted setup costs. */
do {
mtfSymbol[i] = mtfSymbol[i-1];
} while (--i);
byteCount[uc]++;
dbuf[dbufCount++] = (unsigned int)uc;
}
- /* At this point, we've finished reading huffman-coded symbols and
- compressed runs from the input stream. There are dbufCount many of
- them in dbuf[]. Now undo the Burrows-Wheeler transform on dbuf.
+ /* At this point, we've read all the huffman-coded symbols (and repeated
+ runs) for this block from the input stream, and decoded them into the
+ 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
*/
-
- /* 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. */
j=0;
for(i=0;i<256;i++) {
}
/* Figure out what order dbuf would be in if we sorted it. */
for (i=0;i<dbufCount;i++) {
- uc = (unsigned char)(dbuf[i] & 0xff);
+ uc=(unsigned char)(dbuf[i] & 0xff);
dbuf[byteCount[uc]] |= (i << 8);
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
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
- to 1 or get reset). */
+ it doesn't qualify as a run (hence writeRunCountdown=5). */
if(dbufCount) {
+ if(origPtr>=dbufCount) return RETVAL_DATA_ERROR;
bd->writePos=dbuf[origPtr];
bd->writeCurrent=(unsigned char)(bd->writePos&0xff);
bd->writePos>>=8;
- bd->writeRun=-1;
+ bd->writeRunCountdown=5;
}
bd->writeCount=dbufCount;
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.
- If !len, write up to len bytes of data to buf. Otherwise write to out_fd.
- Returns len ? bytes written : RETVAL_OK. Notice all errors negative #'s. */
-extern int write_bunzip_data(bunzip_data *bd, int out_fd, char *outbuf, int len)
+ If start_bunzip was initialized with out_fd=-1, then up to len bytes of
+ data are written to outbuf. Return value is number of bytes written or
+ 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.
+*/
+
+extern int read_bunzip(bunzip_data *bd, char *outbuf, int len)
{
- unsigned int *dbuf=bd->dbuf;
- int count,pos,current, run,copies,outbyte,previous,gotcount=0;
+ 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(bd->writeCount<0) return bd->writeCount;
- /* If we need to refill dbuf, do it. */
- if(!bd->writeCount) {
- int i=read_bunzip_data(bd);
- if(i) {
- if(i==RETVAL_LAST_BLOCK) {
- bd->writeCount=i;
- return gotcount;
- } else return i;
+ /* If last read was short due to end of file, return last block now */
+ if(bd->writeCount<0) return bd->writeCount;
+
+ gotcount = 0;
+ dbuf=bd->dbuf;
+ pos=bd->writePos;
+ current=bd->writeCurrent;
+
+ /* We will always have pending decoded data to write into the output
+ buffer unless this is the very first call (in which case we haven't
+ huffman-decoded a block into the intermediate buffer yet). */
+
+ 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;
}
- }
- /* Loop generating output */
- count=bd->writeCount;
- pos=bd->writePos;
- current=bd->writeCurrent;
- run=bd->writeRun;
- while(count) {
- /* If somebody (like busybox tar) wants a certain number of bytes of
- data from memory instead of written to a file, humor them */
- if(len && bd->outbufPos>=len) goto dataus_interruptus;
- count--;
+ /* 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 */
previous=current;
pos=dbuf[pos];
current=pos&0xff;
pos>>=8;
- /* Whenever we see 3 consecutive copies of the same byte,
- the 4th is a repeat count */
- if(run++==3) {
- copies=current;
- outbyte=previous;
- current=-1;
+ /* After 3 consecutive copies of the same byte, the 4th is a repeat
+ count. We count down from 4 instead
+ * of counting up because testing for non-zero is faster */
+ if(--bd->writeRunCountdown) {
+ if(current!=previous) bd->writeRunCountdown=4;
} else {
- copies=1;
- outbyte=current;
- }
- /* 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];
+ /* We have a repeated run, this byte indicates the count */
+ 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;
}
- if(current!=previous) run=0;
}
/* Decompression of this block completed successfully */
- bd->dataCRC=~(bd->dataCRC);
- bd->totalCRC=((bd->totalCRC << 1) | (bd->totalCRC >> 31)) ^ bd->dataCRC;
+ bd->writeCRC=~bd->writeCRC;
+ bd->totalCRC=((bd->totalCRC<<1) | (bd->totalCRC>>31)) ^ bd->writeCRC;
/* 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;
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;
- }
- }
}
+
+ /* Refill the intermediate buffer by huffman-decoding next block of input */
+ /* (previous is just a convenient unused temp variable here) */
+ 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 !len, src_fd contains
- filehandle to read from. Else inbuf contains data. */
-extern int start_bunzip(bunzip_data **bdp, int src_fd, char *inbuf, int len)
+/* 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;
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 */
i=sizeof(bunzip_data);
- if(!len) i+=IOBUF_SIZE;
+ if(in_fd!=-1) i+=IOBUF_SIZE;
/* Allocate bunzip_data. Most fields initialize to zero. */
if(!(bd=*bdp=malloc(i))) return RETVAL_OUT_OF_MEMORY;
memset(bd,0,sizeof(bunzip_data));
- if(len) {
+ /* Setup input buffer */
+ if(-1==(bd->in_fd=in_fd)) {
bd->inbuf=inbuf;
bd->inbufCount=len;
- bd->in_fd=-1;
- } else {
- bd->inbuf=(char *)(bd+1);
- bd->in_fd=src_fd;
- }
+ } else bd->inbuf=(unsigned char *)(bd+1);
/* Init the CRC32 table (big endian) */
for(i=0;i<256;i++) {
c=i<<24;
/* Setup for I/O error handling via longjmp */
i=setjmp(bd->jmpbuf);
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;
- /* Next byte ascii '1'-'9', indicates block size in units of 100k of
+
+ /* Ensure that file starts with "BZh['1'-'9']." */
+ 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. */
- i=get_bits(bd,8);
- if (i<'1' || i>'9') return RETVAL_NOT_BZIP_DATA;
- bd->dbufSize=100000*(i-'0');
+ bd->dbufSize=100000*(i-BZh0);
+
if(!(bd->dbuf=malloc(bd->dbufSize * sizeof(int))))
return RETVAL_OUT_OF_MEMORY;
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;
int i;
+ if(!(outbuf=malloc(IOBUF_SIZE))) return RETVAL_OUT_OF_MEMORY;
if(!(i=start_bunzip(&bd,src_fd,0,0))) {
- i=write_bunzip_data(bd,dst_fd,0,0);
- if(i==RETVAL_LAST_BLOCK && bd->headerCRC==bd->totalCRC) i=RETVAL_OK;
+ for(;;) {
+ 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);
free(bd);
- return bunzip_errors[-i];
+ free(outbuf);
+ return i;
}
-/* This new version is not yet properly integrated with tar */
-extern ssize_t read_bz2(int fd, void *buf, size_t count)
-{
-#warning FIXME
- return(0);
-}
+#ifdef TESTING
-extern void BZ2_bzReadOpen(int fd, void *unused, int nUnused)
-{
-#warning FIXME
- return;
-}
-extern void BZ2_bzReadClose(void)
-{
-#warning FIXME
-}
+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."};
-#if 0
/* Dumb little test thing, decompress stdin to stdout */
int main(int argc, char *argv[])
{
- char *c=uncompressStream(0,1);
- fprintf(stderr,"\n%s\n", c ? c : "Completed OK");
+ int i=uncompressStream(0,1);
+ 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
projects / oweals / busybox.git / commitdiff