code / linux / torvalds / linux / a3790a8a94fc0234c5d38013b48e74ef221ec84c / . / lib / decompress_bunzip2.c

/* Small bzip2 deflate implementation, 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. | |

This code is licensed under the LGPLv2: | |

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 | |

https://www.hospiceacadiana.com/ | |

Manuel | |

*/ | |

/* | |

Made it fit for running in Linux Kernel by Alain Knaff (alain@knaff.lu) | |

*/ | |

#ifdef STATIC | |

#define PREBOOT | |

#else | |

#include <linux/decompress/bunzip2.h> | |

#endif /* STATIC */ | |

#include <linux/decompress/mm.h> | |

#include <linux/crc32poly.h> | |

#ifndef INT_MAX | |

#define INT_MAX 0x7fffffff | |

#endif | |

/* 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 BZIP2_IOBUF_SIZE 4096 | |

/* 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]; | |

int base[MAX_HUFCODE_BITS]; | |

int permute[MAX_SYMBOLS]; | |

int minLen, maxLen; | |

}; | |

/* Structure holding all the housekeeping data, including IO buffers and | |

memory that persists between calls to bunzip */ | |

struct bunzip_data { | |

/* State for interrupting output loop */ | |

int writeCopies, writePos, writeRunCountdown, writeCount, writeCurrent; | |

/* I/O tracking data (file handles, buffers, positions, etc.) */ | |

long (*fill)(void*, unsigned long); | |

long inbufCount, inbufPos /*, outbufPos*/; | |

unsigned char *inbuf /*,*outbuf*/; | |

unsigned int inbufBitCount, inbufBits; | |

/* The CRC values stored in the block header and calculated from the | |

data */ | |

unsigned int crc32Table[256], headerCRC, totalCRC, writeCRC; | |

/* Intermediate buffer and its size (in bytes) */ | |

unsigned int *dbuf, dbufSize; | |

/* 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 */ | |

int io_error; /* non-zero if we have IO error */ | |

int byteCount[256]; | |

unsigned char symToByte[256], mtfSymbol[256]; | |

}; | |

/* 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 INIT get_bits(struct 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->io_error) | |

return 0; | |

bd->inbufCount = bd->fill(bd->inbuf, BZIP2_IOBUF_SIZE); | |

if (bd->inbufCount <= 0) { | |

bd->io_error = RETVAL_UNEXPECTED_INPUT_EOF; | |

return 0; | |

} | |

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; | |

} | |

/* Unpacks the next block and sets up for the inverse burrows-wheeler step. */ | |

static int INIT get_next_block(struct bunzip_data *bd) | |

{ | |

struct group_data *hufGroup = NULL; | |

int *base = NULL; | |

int *limit = NULL; | |

int dbufCount, nextSym, dbufSize, groupCount, selector, | |

i, j, k, t, runPos, symCount, symTotal, nSelectors, *byteCount; | |

unsigned char uc, *symToByte, *mtfSymbol, *selectors; | |

unsigned int *dbuf, origPtr; | |

dbuf = bd->dbuf; | |

dbufSize = bd->dbufSize; | |

selectors = bd->selectors; | |

byteCount = bd->byteCount; | |

symToByte = bd->symToByte; | |

mtfSymbol = bd->mtfSymbol; | |

/* 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. */ | |

if (get_bits(bd, 1)) | |

return RETVAL_OBSOLETE_INPUT; | |

origPtr = get_bits(bd, 24); | |

if (origPtr >= 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); | |

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. (MTF = Move To | |

Front, as each value is used it's moved to the start of the | |

list.) */ | |

nSelectors = get_bits(bd, 15); | |

if (!nSelectors) | |

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]; | |

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 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 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 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); | |

} | |

/* 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]; | |

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. 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; | |

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[]. Concurrently, 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 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 | |

*minus the cumulative count of symbols coded for | |

*already). */ | |

pp = t = 0; | |

for (i = minLen; i < maxLen; i++) { | |

pp += temp[i]; | |

/* 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]); | |

} | |

limit[maxLen+1] = INT_MAX; /* Sentinal value for | |

* reading next sym. */ | |

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 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. */ | |

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. */ | |

/* 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 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]; | |

/* 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) { | |

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. */ | |

t += (runPos << nextSym); | |

/* +runPos if RUNA; +2*runPos if RUNB */ | |

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, 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]; | |

/* 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); | |

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 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 | |

*/ | |

/* 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]++; | |

} | |

/* 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 | |

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->writeRunCountdown = 5; | |

} | |

bd->writeCount = dbufCount; | |

return RETVAL_OK; | |

} | |

/* Undo burrows-wheeler transform on intermediate buffer to produce output. | |

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. | |

*/ | |

static int INIT read_bunzip(struct bunzip_data *bd, char *outbuf, int len) | |

{ | |

const unsigned int *dbuf; | |

int pos, xcurrent, previous, gotcount; | |

/* 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; | |

xcurrent = 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 = xcurrent; | |

bd->writeCopies++; | |

return len; | |

} | |

/* Write next byte into output buffer, updating CRC */ | |

outbuf[gotcount++] = xcurrent; | |

bd->writeCRC = (((bd->writeCRC) << 8) | |

^bd->crc32Table[((bd->writeCRC) >> 24) | |

^xcurrent]); | |

/* 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 = xcurrent; | |

pos = dbuf[pos]; | |

xcurrent = pos&0xff; | |

pos >>= 8; | |

/* 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 (xcurrent != previous) | |

bd->writeRunCountdown = 4; | |

} else { | |

/* We have a repeated run, this byte | |

* indicates the count */ | |

bd->writeCopies = xcurrent; | |

xcurrent = 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; | |

} | |

} | |

/* Decompression of this block completed successfully */ | |

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->writeCRC != bd->headerCRC) { | |

bd->totalCRC = bd->headerCRC+1; | |

return RETVAL_LAST_BLOCK; | |

} | |

} | |

/* 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; | |

xcurrent = bd->writeCurrent; | |

goto decode_next_byte; | |

} | |

static long INIT nofill(void *buf, unsigned long len) | |

{ | |

return -1; | |

} | |

/* 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. */ | |

static int INIT start_bunzip(struct bunzip_data **bdp, void *inbuf, long len, | |

long (*fill)(void*, unsigned long)) | |

{ | |

struct 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(struct bunzip_data); | |

/* Allocate bunzip_data. Most fields initialize to zero. */ | |

bd = *bdp = malloc(i); | |

if (!bd) | |

return RETVAL_OUT_OF_MEMORY; | |

memset(bd, 0, sizeof(struct bunzip_data)); | |

/* Setup input buffer */ | |

bd->inbuf = inbuf; | |

bd->inbufCount = len; | |

if (fill != NULL) | |

bd->fill = fill; | |

else | |

bd->fill = nofill; | |

/* 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)^(CRC32_POLY_BE) : (c << 1); | |

bd->crc32Table[i] = c; | |

} | |

/* 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. */ | |

bd->dbufSize = 100000*(i-BZh0); | |

bd->dbuf = large_malloc(bd->dbufSize * sizeof(int)); | |

if (!bd->dbuf) | |

return RETVAL_OUT_OF_MEMORY; | |

return RETVAL_OK; | |

} | |

/* Example usage: decompress src_fd to dst_fd. (Stops at end of bzip2 data, | |

not end of file.) */ | |

STATIC int INIT bunzip2(unsigned char *buf, long len, | |

long (*fill)(void*, unsigned long), | |

long (*flush)(void*, unsigned long), | |

unsigned char *outbuf, | |

long *pos, | |

void(*error)(char *x)) | |

{ | |

struct bunzip_data *bd; | |

int i = -1; | |

unsigned char *inbuf; | |

if (flush) | |

outbuf = malloc(BZIP2_IOBUF_SIZE); | |

if (!outbuf) { | |

error("Could not allocate output buffer"); | |

return RETVAL_OUT_OF_MEMORY; | |

} | |

if (buf) | |

inbuf = buf; | |

else | |

inbuf = malloc(BZIP2_IOBUF_SIZE); | |

if (!inbuf) { | |

error("Could not allocate input buffer"); | |

i = RETVAL_OUT_OF_MEMORY; | |

goto exit_0; | |

} | |

i = start_bunzip(&bd, inbuf, len, fill); | |

if (!i) { | |

for (;;) { | |

i = read_bunzip(bd, outbuf, BZIP2_IOBUF_SIZE); | |

if (i <= 0) | |

break; | |

if (!flush) | |

outbuf += i; | |

else | |

if (i != flush(outbuf, i)) { | |

i = RETVAL_UNEXPECTED_OUTPUT_EOF; | |

break; | |

} | |

} | |

} | |

/* Check CRC and release memory */ | |

if (i == RETVAL_LAST_BLOCK) { | |

if (bd->headerCRC != bd->totalCRC) | |

error("Data integrity error when decompressing."); | |

else | |

i = RETVAL_OK; | |

} else if (i == RETVAL_UNEXPECTED_OUTPUT_EOF) { | |

error("Compressed file ends unexpectedly"); | |

} | |

if (!bd) | |

goto exit_1; | |

if (bd->dbuf) | |

large_free(bd->dbuf); | |

if (pos) | |

*pos = bd->inbufPos; | |

free(bd); | |

exit_1: | |

if (!buf) | |

free(inbuf); | |

exit_0: | |

if (flush) | |

free(outbuf); | |

return i; | |

} | |

#ifdef PREBOOT | |

STATIC int INIT __decompress(unsigned char *buf, long len, | |

long (*fill)(void*, unsigned long), | |

long (*flush)(void*, unsigned long), | |

unsigned char *outbuf, long olen, | |

long *pos, | |

void (*error)(char *x)) | |

{ | |

return bunzip2(buf, len - 4, fill, flush, outbuf, pos, error); | |

} | |

#endif |