--- /dev/null
+/* vi: set sw=4 ts=4: */
+/* micro-bunzip, a small, simple bzip2 decompression implementation.
+
+ Copyright 2003, 2006 by Rob Landley (rob@landley.net).
+
+ Based on bzip2 decompression code by Julian R Seward (jseward@acm.org),
+ which also acknowledges contributions by Mike Burrows, David Wheeler, Peter
+ Fenwick, Alistair Moffat, Radford Neal, Ian H. Witten, Robert Sedgewick, and
+ Jon L. Bentley. (Didn't actually use any of their code, though.)
+*/
+
+#include "toys.h"
+
+/* Constants for huffman coding */
+#define MAX_GROUPS 6
+#define GROUP_SIZE 50 /* 64 would have been more efficient */
+#define MAX_HUFCODE_BITS 20 /* Longest huffman code allowed */
+#define MAX_SYMBOLS 258 /* 256 literals + RUNA + RUNB */
+#define SYMBOL_RUNA 0
+#define SYMBOL_RUNB 1
+
+/* Status return values */
+#define RETVAL_OK 0
+#define RETVAL_LAST_BLOCK (-1)
+#define RETVAL_NOT_BZIP_DATA (-2)
+#define RETVAL_UNEXPECTED_INPUT_EOF (-3)
+#define RETVAL_UNEXPECTED_OUTPUT_EOF (-4)
+#define RETVAL_DATA_ERROR (-5)
+#define RETVAL_OUT_OF_MEMORY (-6)
+#define RETVAL_OBSOLETE_INPUT (-7)
+
+/* Other housekeeping constants */
+#define IOBUF_SIZE 4096
+
+char *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 {
+ int limit[MAX_HUFCODE_BITS],base[MAX_HUFCODE_BITS],permute[MAX_SYMBOLS];
+ char 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;
+ 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;
+ /* 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 */
+} bunzip_data;
+
+/* Return the next nnn bits of input. All reads from the compressed input
+ are done through this function. All reads are big endian */
+static unsigned int get_bits(bunzip_data *bd, char bits_wanted)
+{
+ unsigned int bits=0;
+
+ /* If we need to get more data from the byte buffer, do so. (Loop getting
+ one byte at a time to enforce endianness and avoid unaligned access.) */
+ while (bd->inbufBitCount<bits_wanted) {
+ /* If we need to read more data from file into byte buffer, do so */
+ if(bd->inbufPos==bd->inbufCount) {
+ if(!(bd->inbufCount = read(bd->in_fd, bd->inbuf, IOBUF_SIZE)))
+ longjmp(bd->jmpbuf,RETVAL_UNEXPECTED_INPUT_EOF);
+ bd->inbufPos=0;
+ }
+ /* Avoid 32-bit overflow (dump bit buffer to top of output) */
+ if(bd->inbufBitCount>=24) {
+ bits=bd->inbufBits&((1<<bd->inbufBitCount)-1);
+ bits_wanted-=bd->inbufBitCount;
+ bits<<=bits_wanted;
+ bd->inbufBitCount=0;
+ }
+ /* Grab next 8 bits of input from buffer. */
+ bd->inbufBits=(bd->inbufBits<<8)|bd->inbuf[bd->inbufPos++];
+ bd->inbufBitCount+=8;
+ }
+ /* Calculate result */
+ bd->inbufBitCount-=bits_wanted;
+ bits|=(bd->inbufBits>>bd->inbufBitCount)&((1<<bits_wanted)-1);
+
+ return bits;
+}
+
+/* Decompress a block of text to into intermediate buffer */
+
+extern int read_bunzip_data(bunzip_data *bd)
+{
+ struct group_data *hufGroup;
+ int dbufCount,nextSym,dbufSize,origPtr,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;
+
+ dbuf=bd->dbuf;
+ dbufSize=bd->dbufSize;
+ selectors=bd->selectors;
+ /* 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. */
+ if(get_bits(bd,1)) return RETVAL_OBSOLETE_INPUT;
+ if((origPtr=get_bits(bd,24)) > dbufSize) return RETVAL_DATA_ERROR;
+ /* mapping table: if some byte values are never used (encoding things
+ like ascii text), the compression code removes the gaps to have fewer
+ symbols to deal with, and writes a sparse bitfield indicating which
+ values were present. We make a translation table to convert the symbols
+ back to the corresponding bytes. */
+ t=get_bits(bd, 16);
+ memset(symToByte,0,256);
+ symTotal=0;
+ for (i=0;i<16;i++) {
+ if(t&(1<<(15-i))) {
+ k=get_bits(bd,16);
+ for(j=0;j<16;j++)
+ if(k&(1<<(15-j))) symToByte[symTotal++]=(16*i)+j;
+ }
+ }
+ /* How many different huffman coding groups does this block use? */
+ groupCount=get_bits(bd,3);
+ 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. */
+ 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++) {
+ /* Get next value */
+ 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];
+ memmove(mtfSymbol+1,mtfSymbol,j);
+ mtfSymbol[0]=selectors[i]=uc;
+ }
+ /* Read the huffman coding tables for each group, which code for symTotal
+ literal symbols, plus two run symbols (RUNA, RUNB) */
+ symCount=symTotal+2;
+ 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);
+ for (i = 0; i < symCount; i++) {
+ for(;;) {
+ if (t < 1 || t > MAX_HUFCODE_BITS) return RETVAL_DATA_ERROR;
+ if(!get_bits(bd, 1)) break;
+ if(!get_bits(bd, 1)) t++;
+ else t--;
+ }
+ length[i] = t;
+ }
+ /* Find largest and smallest lengths in this group */
+ minLen=maxLen=length[0];
+ for(i = 1; i < symCount; i++) {
+ if(length[i] > maxLen) maxLen = length[i];
+ else if(length[i] < minLen) minLen = length[i];
+ }
+ /* Calculate permute[], base[], and limit[] tables from length[].
+ *
+ * permute[] is the lookup table for converting huffman coded symbols
+ * into decoded symbols. base[] is the amount to subtract from the
+ * 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]].
+ */
+ hufGroup=bd->groups+j;
+ hufGroup->minLen = minLen;
+ hufGroup->maxLen = maxLen;
+ /* Note that minLen can't be smaller than 1, so we adjust the base
+ and limit array pointers so we're not always wasting the first
+ 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++)
+ 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;
+ 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). */
+ pp=t=0;
+ for (i=minLen; i<maxLen; i++) {
+ pp+=temp[i];
+ limit[i]=pp-1;
+ pp<<=1;
+ base[i+1]=pp-(t+=temp[i]);
+ }
+ limit[maxLen]=pp+temp[maxLen]-1;
+ base[minLen]=0;
+ }
+ /* We've finished reading and digesting the block header. Now read this
+ 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 */
+ runPos=dbufCount=symCount=selector=0;
+ for(;;) {
+ /* Determine which huffman coding group to use. */
+ if(!(symCount--)) {
+ symCount=GROUP_SIZE-1;
+ if(selector>=nSelectors) return RETVAL_DATA_ERROR;
+ hufGroup=bd->groups+selectors[selector++];
+ base=hufGroup->base-1;
+ limit=hufGroup->limit-1;
+ }
+ /* Read next huffman-coded symbol */
+ i = hufGroup->minLen;
+ j=get_bits(bd, i);
+ for(;;) {
+ if (i > hufGroup->maxLen) return RETVAL_DATA_ERROR;
+ if (j <= limit[i]) break;
+ i++;
+
+ j = (j << 1) | get_bits(bd,1);
+ }
+ /* Huffman decode nextSym (with bounds checking) */
+ j-=base[i];
+ if (j < 0 || j >= MAX_SYMBOLS) return RETVAL_DATA_ERROR;
+ nextSym = hufGroup->permute[j];
+ /* If this is a repeated run, loop collecting data */
+ if (nextSym == SYMBOL_RUNA || nextSym == SYMBOL_RUNB) {
+ /* If this is the start of a new run, zero out counter */
+ if(!runPos) {
+ runPos = 1;
+ t = 0;
+ }
+ /* Neat trick that saves 1 symbol: instead of or-ing 0 or 1 at
+ each bit position, add 1 or 2 instead. For example,
+ 1011 is 1<<0 + 1<<1 + 2<<2. 1010 is 2<<0 + 2<<1 + 1<<2.
+ You can make any bit pattern that way using 1 less symbol than
+ the basic or 0/1 method (except all bits 0, which would use no
+ symbols, but a run of length 0 doesn't mean anything in this
+ context). Thus space is saved. */
+ if (nextSym == SYMBOL_RUNA) t += runPos;
+ else t += 2*runPos;
+ runPos <<= 1;
+ continue;
+ }
+ /* When we hit the first non-run symbol after a run, we now know
+ how many times to repeat the last literal, so append that many
+ copies to our buffer of decoded symbols (dbuf) now. (The last
+ literal used is the one at the head of the mtfSymbol array.) */
+ if(runPos) {
+ runPos=0;
+ if(dbufCount+t>=dbufSize) return RETVAL_DATA_ERROR;
+
+ uc = symToByte[mtfSymbol[0]];
+ byteCount[uc] += t;
+ while(t--) dbuf[dbufCount++]=uc;
+ }
+ /* 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.) */
+ if(dbufCount>=dbufSize) return RETVAL_DATA_ERROR;
+ i = nextSym - 1;
+ uc = mtfSymbol[i];
+ memmove(mtfSymbol+1,mtfSymbol,i);
+ mtfSymbol[0] = uc;
+ uc=symToByte[uc];
+ /* We have our literal byte. Save it into dbuf. */
+ 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.
+ See http://dogma.net/markn/articles/bwt/bwt.htm
+ */
+
+ /* Now we know what dbufCount is, do a better sanity check on origPtr. */
+ if (origPtr<0 || 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++) {
+ k=j+byteCount[i];
+ byteCount[i] = j;
+ j=k;
+ }
+ /* Figure out what order dbuf would be in if we sorted it. */
+ for (i=0;i<dbufCount;i++) {
+ 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). */
+ if(dbufCount) {
+ bd->writePos=dbuf[origPtr];
+ bd->writeCurrent=(unsigned char)(bd->writePos&0xff);
+ bd->writePos>>=8;
+ bd->writeRun=-1;
+ }
+ 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)
+{
+ unsigned int *dbuf=bd->dbuf;
+ int count,pos,current, run,copies,outbyte,previous,gotcount=0;
+
+ 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;
+ }
+ }
+ /* 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--;
+ /* 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;
+ } 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];
+ }
+ 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;
+ /* If this block had a CRC error, force file level CRC error. */
+ if(bd->dataCRC!=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;
+ }
+ }
+ }
+}
+
+/* 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)
+{
+ bunzip_data *bd;
+ unsigned int i,j,c;
+
+ /* Figure out how much data to allocate */
+ i=sizeof(bunzip_data);
+ if(!len) 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) {
+ bd->inbuf=inbuf;
+ bd->inbufCount=len;
+ bd->in_fd=-1;
+ } else {
+ bd->inbuf=(char *)(bd+1);
+ bd->in_fd=src_fd;
+ }
+ /* Init the CRC32 table (big endian) */
+ for(i=0;i<256;i++) {
+ c=i<<24;
+ for(j=8;j;j--)
+ c=c&0x80000000 ? (c<<1)^0x04c11db7 : (c<<1);
+ bd->crc32Table[i]=c;
+ }
+ /* 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
+ 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');
+ if(!(bd->dbuf=malloc(bd->dbufSize * sizeof(int))))
+ return RETVAL_OUT_OF_MEMORY;
+ return RETVAL_OK;
+}
+
+/* Example usage: decompress src_fd to dst_fd. (Stops at end of bzip data,
+ not end of file.) */
+extern char *uncompressStream(int src_fd, int dst_fd)
+{
+ bunzip_data *bd;
+ int i;
+
+ 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;
+ }
+ flush_bunzip_outbuf(bd,dst_fd);
+ if(bd->dbuf) free(bd->dbuf);
+ free(bd);
+ return bunzip_errors[-i];
+}
projects / platform / upstream / toybox.git / commitdiff