nest-open-source / nest-learning-thermostat / 5.1 / busybox / 4e78bdb482363ce3d708250ad80a9b303c48ade7 / . / busybox-1.19.3 / archival / libarchive / decompress_bunzip2.c

/* vi: set sw=4 ts=4: */ | |

/* 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. | |

Licensed under GPLv2 or later, see file LICENSE in this source tree. | |

*/ | |

/* | |

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_bunzip() reversing | |

the Burrows-Wheeler transformation. Much of that time is delay | |

resulting from cache misses. | |

(2010 update by vda: profiled "bzcat <84mbyte.bz2 >/dev/null" | |

on x86-64 CPU with L2 > 1M: get_next_block is hotter than read_bunzip: | |

%time seconds calls function | |

71.01 12.69 444 get_next_block | |

28.65 5.12 93065 read_bunzip | |

00.22 0.04 7736490 get_bits | |

00.11 0.02 47 dealloc_bunzip | |

00.00 0.00 93018 full_write | |

...) | |

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 (www.hospiceacadiana.com) in the name of | |

the woman I loved, Toni W. Hagan, who passed away Feb. 12, 2003. | |

Manuel | |

*/ | |

#include "libbb.h" | |

#include "archive.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_SHORT_WRITE (-4) | |

#define RETVAL_DATA_ERROR (-5) | |

#define RETVAL_OUT_OF_MEMORY (-6) | |

#define RETVAL_OBSOLETE_INPUT (-7) | |

/* Other housekeeping constants */ | |

#define 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 sentinel value. */ | |

int limit[MAX_HUFCODE_BITS+1], base[MAX_HUFCODE_BITS], permute[MAX_SYMBOLS]; | |

int minLen, maxLen; | |

}; | |

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

* memory that persists between calls to bunzip | |

* Found the most used member: | |

* cat this_file.c | sed -e 's/"/ /g' -e "s/'/ /g" | xargs -n1 \ | |

* | grep 'bd->' | sed 's/^.*bd->/bd->/' | sort | $PAGER | |

* and moved it (inbufBitCount) to offset 0. | |

*/ | |

struct bunzip_data { | |

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

unsigned inbufBitCount, inbufBits; | |

int in_fd, out_fd, inbufCount, inbufPos /*, outbufPos*/; | |

uint8_t *inbuf /*,*outbuf*/; | |

/* State for interrupting output loop */ | |

int writeCopies, writePos, writeRunCountdown, writeCount; | |

int writeCurrent; /* actually a uint8_t */ | |

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

uint32_t headerCRC, totalCRC, writeCRC; | |

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

uint32_t *dbuf; | |

unsigned dbufSize; | |

/* For I/O error handling */ | |

jmp_buf jmpbuf; | |

/* Big things go last (register-relative addressing can be larger for big offsets) */ | |

uint32_t crc32Table[256]; | |

uint8_t selectors[32768]; /* nSelectors=15 bits */ | |

struct group_data groups[MAX_GROUPS]; /* Huffman coding tables */ | |

}; | |

/* typedef struct bunzip_data bunzip_data; -- done in .h file */ | |

/* 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 get_bits(bunzip_data *bd, int bits_wanted) | |

{ | |

unsigned bits = 0; | |

/* Cache bd->inbufBitCount in a CPU register (hopefully): */ | |

int bit_count = bd->inbufBitCount; | |

/* 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 (bit_count < bits_wanted) { | |

/* If we need to read more data from file into byte buffer, do so */ | |

if (bd->inbufPos == bd->inbufCount) { | |

/* if "no input fd" case: in_fd == -1, read fails, we jump */ | |

bd->inbufCount = read(bd->in_fd, bd->inbuf, IOBUF_SIZE); | |

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

longjmp(bd->jmpbuf, RETVAL_UNEXPECTED_INPUT_EOF); | |

bd->inbufPos = 0; | |

} | |

/* Avoid 32-bit overflow (dump bit buffer to top of output) */ | |

if (bit_count >= 24) { | |

bits = bd->inbufBits & ((1 << bit_count) - 1); | |

bits_wanted -= bit_count; | |

bits <<= bits_wanted; | |

bit_count = 0; | |

} | |

/* Grab next 8 bits of input from buffer. */ | |

bd->inbufBits = (bd->inbufBits << 8) | bd->inbuf[bd->inbufPos++]; | |

bit_count += 8; | |

} | |

/* Calculate result */ | |

bit_count -= bits_wanted; | |

bd->inbufBitCount = bit_count; | |

bits |= (bd->inbufBits >> bit_count) & ((1 << bits_wanted) - 1); | |

return bits; | |

} | |

/* Unpacks the next block and sets up for the inverse Burrows-Wheeler step. */ | |

static int get_next_block(bunzip_data *bd) | |

{ | |

struct group_data *hufGroup; | |

int dbufCount, dbufSize, groupCount, *base, *limit, selector, | |

i, j, t, runPos, symCount, symTotal, nSelectors, byteCount[256]; | |

int runCnt = runCnt; /* for compiler */ | |

uint8_t uc, symToByte[256], mtfSymbol[256], *selectors; | |

uint32_t *dbuf; | |

unsigned origPtr; | |

dbuf = bd->dbuf; | |

dbufSize = bd->dbufSize; | |

selectors = bd->selectors; | |

/* In bbox, we are ok with aborting through setjmp which is set up in start_bunzip */ | |

#if 0 | |

/* Reset longjmp I/O error handling */ | |

i = setjmp(bd->jmpbuf); | |

if (i) return i; | |

#endif | |

/* 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 ((int)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. */ | |

symTotal = 0; | |

i = 0; | |

t = get_bits(bd, 16); | |

do { | |

if (t & (1 << 15)) { | |

unsigned inner_map = get_bits(bd, 16); | |

do { | |

if (inner_map & (1 << 15)) | |

symToByte[symTotal++] = i; | |

inner_map <<= 1; | |

i++; | |

} while (i & 15); | |

i -= 16; | |

} | |

t <<= 1; | |

i += 16; | |

} while (i < 256); | |

/* 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.) */ | |

for (i = 0; i < groupCount; i++) | |

mtfSymbol[i] = i; | |

nSelectors = get_bits(bd, 15); | |

if (!nSelectors) | |

return RETVAL_DATA_ERROR; | |

for (i = 0; i < nSelectors; i++) { | |

uint8_t tmp_byte; | |

/* Get next value */ | |

int n = 0; | |

while (get_bits(bd, 1)) { | |

if (n >= groupCount) return RETVAL_DATA_ERROR; | |

n++; | |

} | |

/* Decode MTF to get the next selector */ | |

tmp_byte = mtfSymbol[n]; | |

while (--n >= 0) | |

mtfSymbol[n + 1] = mtfSymbol[n]; | |

mtfSymbol[0] = selectors[i] = tmp_byte; | |

} | |

/* 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++) { | |

uint8_t length[MAX_SYMBOLS]; | |

/* 8 bits is ALMOST enough for temp[], see below */ | |

unsigned temp[MAX_HUFCODE_BITS+1]; | |

int minLen, maxLen, pp, len_m1; | |

/* 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 every 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.) */ | |

len_m1 = get_bits(bd, 5) - 1; | |

for (i = 0; i < symCount; i++) { | |

for (;;) { | |

int two_bits; | |

if ((unsigned)len_m1 > (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. */ | |

two_bits = get_bits(bd, 2); | |

if (two_bits < 2) { | |

bd->inbufBitCount++; | |

break; | |

} | |

/* Add one if second bit 1, else subtract 1. Avoids if/else */ | |

len_m1 += (((two_bits+1) & 2) - 1); | |

} | |

/* Correct for the initial -1, to get the final symbol length */ | |

length[i] = len_m1 + 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[]. Concurently, initialize temp[] and limit[]. */ | |

pp = 0; | |

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

int k; | |

temp[i] = limit[i] = 0; | |

for (k = 0; k < symCount; k++) | |

if (length[k] == i) | |

hufGroup->permute[pp++] = k; | |

} | |

/* Count symbols coded for at each bit length */ | |

/* NB: in pathological cases, temp[8] can end ip being 256. | |

* That's why uint8_t is too small for temp[]. */ | |

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;) { | |

unsigned temp_i = temp[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; | |

t += temp_i; | |

base[++i] = pp - t; | |

} | |

limit[maxLen] = pp + temp[maxLen] - 1; | |

limit[maxLen+1] = INT_MAX; /* Sentinel value for reading next sym. */ | |

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 */ | |

/*memset(byteCount, 0, sizeof(byteCount)); - smaller, but slower */ | |

for (i = 0; i < 256; i++) { | |

byteCount[i] = 0; | |

mtfSymbol[i] = (uint8_t)i; | |

} | |

/* Loop through compressed symbols. */ | |

runPos = dbufCount = selector = 0; | |

for (;;) { | |

int nextSym; | |

/* Fetch next Huffman coding group from list. */ | |

symCount = GROUP_SIZE - 1; | |

if (selector >= nSelectors) return RETVAL_DATA_ERROR; | |

hufGroup = bd->groups + selectors[selector++]; | |

base = hufGroup->base - 1; | |

limit = hufGroup->limit - 1; | |

continue_this_group: | |

/* 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 add 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. | |

*/ | |

if (1) { | |

/* As a further optimization, we do the read inline | |

(falling back to a call to get_bits if the buffer runs dry). | |

*/ | |

int new_cnt; | |

while ((new_cnt = bd->inbufBitCount - hufGroup->maxLen) < 0) { | |

/* bd->inbufBitCount < hufGroup->maxLen */ | |

if (bd->inbufPos == bd->inbufCount) { | |

nextSym = get_bits(bd, hufGroup->maxLen); | |

goto got_huff_bits; | |

} | |

bd->inbufBits = (bd->inbufBits << 8) | bd->inbuf[bd->inbufPos++]; | |

bd->inbufBitCount += 8; | |

}; | |

bd->inbufBitCount = new_cnt; /* "bd->inbufBitCount -= hufGroup->maxLen;" */ | |

nextSym = (bd->inbufBits >> new_cnt) & ((1 << hufGroup->maxLen) - 1); | |

got_huff_bits: ; | |

} else { /* unoptimized equivalent */ | |

nextSym = get_bits(bd, hufGroup->maxLen); | |

} | |

/* Figure how many bits are in next symbol and unget extras */ | |

i = hufGroup->minLen; | |

while (nextSym > limit[i]) ++i; | |

j = hufGroup->maxLen - i; | |

if (j < 0) | |

return RETVAL_DATA_ERROR; | |

bd->inbufBitCount += j; | |

/* Huffman decode value to get nextSym (with bounds checking) */ | |

nextSym = (nextSym >> j) - base[i]; | |

if ((unsigned)nextSym >= MAX_SYMBOLS) | |

return RETVAL_DATA_ERROR; | |

nextSym = hufGroup->permute[nextSym]; | |

/* 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 == 0) { | |

runPos = 1; | |

runCnt = 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. */ | |

runCnt += (runPos << nextSym); /* +runPos if RUNA; +2*runPos if RUNB */ | |

if (runPos < dbufSize) runPos <<= 1; | |

goto end_of_huffman_loop; | |

} | |

/* 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 != 0) { | |

uint8_t tmp_byte; | |

if (dbufCount + runCnt >= dbufSize) return RETVAL_DATA_ERROR; | |

tmp_byte = symToByte[mtfSymbol[0]]; | |

byteCount[tmp_byte] += runCnt; | |

while (--runCnt >= 0) dbuf[dbufCount++] = (uint32_t)tmp_byte; | |

runPos = 0; | |

} | |

/* 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++] = (uint32_t)uc; | |

/* Skip group initialization if we're not done with this group. Done | |

* this way to avoid compiler warning. */ | |

end_of_huffman_loop: | |

if (--symCount >= 0) goto continue_this_group; | |

} | |

/* 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++) { | |

int tmp_count = j + byteCount[i]; | |

byteCount[i] = j; | |

j = tmp_count; | |

} | |

/* Figure out what order dbuf would be in if we sorted it. */ | |

for (i = 0; i < dbufCount; i++) { | |

uint8_t tmp_byte = (uint8_t)dbuf[i]; | |

int tmp_count = byteCount[tmp_byte]; | |

dbuf[tmp_count] |= (i << 8); | |

byteCount[tmp_byte] = tmp_count + 1; | |

} | |

/* 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) { | |

uint32_t tmp; | |

if ((int)origPtr >= dbufCount) return RETVAL_DATA_ERROR; | |

tmp = dbuf[origPtr]; | |

bd->writeCurrent = (uint8_t)tmp; | |

bd->writePos = (tmp >> 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. | |

NB: read_bunzip returns < 0 on error, or the number of *unfilled* bytes | |

in outbuf. IOW: on EOF returns len ("all bytes are not filled"), not 0. | |

(Why? This allows to get rid of one local variable) | |

*/ | |

int FAST_FUNC read_bunzip(bunzip_data *bd, char *outbuf, int len) | |

{ | |

const uint32_t *dbuf; | |

int pos, current, previous; | |

uint32_t CRC; | |

/* If we already have error/end indicator, return it */ | |

if (bd->writeCount < 0) | |

return bd->writeCount; | |

dbuf = bd->dbuf; | |

/* Register-cached state (hopefully): */ | |

pos = bd->writePos; | |

current = bd->writeCurrent; | |

CRC = bd->writeCRC; /* small loss on x86-32 (not enough regs), win on x86-64 */ | |

/* 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) { | |

dec_writeCopies: | |

/* Inside the loop, writeCopies means extra copies (beyond 1) */ | |

--bd->writeCopies; | |

/* Loop outputting bytes */ | |

for (;;) { | |

/* If the output buffer is full, save cached state and return */ | |

if (--len < 0) { | |

/* Unlikely branch. | |

* Use of "goto" instead of keeping code here | |

* helps compiler to realize this. */ | |

goto outbuf_full; | |

} | |

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

*outbuf++ = current; | |

CRC = (CRC << 8) ^ bd->crc32Table[(CRC >> 24) ^ current]; | |

/* Loop now if we're outputting multiple copies of this byte */ | |

if (bd->writeCopies) { | |

/* Unlikely branch */ | |

/*--bd->writeCopies;*/ | |

/*continue;*/ | |

/* Same, but (ab)using other existing --writeCopies operation | |

* (and this if() compiles into just test+branch pair): */ | |

goto dec_writeCopies; | |

} | |

decode_next_byte: | |

if (--bd->writeCount < 0) | |

break; /* input block is fully consumed, need next one */ | |

/* Follow sequence vector to undo Burrows-Wheeler transform */ | |

previous = current; | |

pos = dbuf[pos]; | |

current = (uint8_t)pos; | |

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 != 0) { | |

if (current != previous) | |

bd->writeRunCountdown = 4; | |

} else { | |

/* Unlikely branch */ | |

/* 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; | |

} | |

} /* for(;;) */ | |

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

bd->writeCRC = CRC = ~CRC; | |

bd->totalCRC = ((bd->totalCRC << 1) | (bd->totalCRC >> 31)) ^ CRC; | |

/* If this block had a CRC error, force file level CRC error */ | |

if (CRC != bd->headerCRC) { | |

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

return RETVAL_LAST_BLOCK; | |

} | |

} | |

/* Refill the intermediate buffer by Huffman-decoding next block of input */ | |

{ | |

int r = get_next_block(bd); | |

if (r) { /* error/end */ | |

bd->writeCount = r; | |

return (r != RETVAL_LAST_BLOCK) ? r : len; | |

} | |

} | |

CRC = ~0; | |

pos = bd->writePos; | |

current = bd->writeCurrent; | |

goto decode_next_byte; | |

outbuf_full: | |

/* Output buffer is full, save cached state and return */ | |

bd->writePos = pos; | |

bd->writeCurrent = current; | |

bd->writeCRC = CRC; | |

bd->writeCopies++; | |

return 0; | |

} | |

/* 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. */ | |

/* Because bunzip2 is used for help text unpacking, and because bb_show_usage() | |

should work for NOFORK applets too, we must be extremely careful to not leak | |

any allocations! */ | |

int FAST_FUNC start_bunzip(bunzip_data **bdp, int in_fd, | |

const void *inbuf, int len) | |

{ | |

bunzip_data *bd; | |

unsigned i; | |

enum { | |

BZh0 = ('B' << 24) + ('Z' << 16) + ('h' << 8) + '0', | |

h0 = ('h' << 8) + '0', | |

}; | |

/* Figure out how much data to allocate */ | |

i = sizeof(bunzip_data); | |

if (in_fd != -1) i += IOBUF_SIZE; | |

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

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

/* Setup input buffer */ | |

bd->in_fd = in_fd; | |

if (-1 == in_fd) { | |

/* in this case, bd->inbuf is read-only */ | |

bd->inbuf = (void*)inbuf; /* cast away const-ness */ | |

} else { | |

bd->inbuf = (uint8_t*)(bd + 1); | |

memcpy(bd->inbuf, inbuf, len); | |

} | |

bd->inbufCount = len; | |

/* Init the CRC32 table (big endian) */ | |

crc32_filltable(bd->crc32Table, 1); | |

/* Setup for I/O error handling via longjmp */ | |

i = setjmp(bd->jmpbuf); | |

if (i) return i; | |

/* Ensure that file starts with "BZh['1'-'9']." */ | |

/* Update: now caller verifies 1st two bytes, makes .gz/.bz2 | |

* integration easier */ | |

/* was: */ | |

/* i = get_bits(bd, 32); */ | |

/* if ((unsigned)(i - BZh0 - 1) >= 9) return RETVAL_NOT_BZIP_DATA; */ | |

i = get_bits(bd, 16); | |

if ((unsigned)(i - h0 - 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->dbufSize = 100000 * (i - h0); | |

/* Cannot use xmalloc - may leak bd in NOFORK case! */ | |

bd->dbuf = malloc_or_warn(bd->dbufSize * sizeof(bd->dbuf[0])); | |

if (!bd->dbuf) { | |

free(bd); | |

xfunc_die(); | |

} | |

return RETVAL_OK; | |

} | |

void FAST_FUNC dealloc_bunzip(bunzip_data *bd) | |

{ | |

free(bd->dbuf); | |

free(bd); | |

} | |

/* Decompress src_fd to dst_fd. Stops at end of bzip data, not end of file. */ | |

IF_DESKTOP(long long) int FAST_FUNC | |

unpack_bz2_stream(int src_fd, int dst_fd) | |

{ | |

IF_DESKTOP(long long total_written = 0;) | |

bunzip_data *bd; | |

char *outbuf; | |

int i; | |

unsigned len; | |

outbuf = xmalloc(IOBUF_SIZE); | |

len = 0; | |

while (1) { /* "Process one BZ... stream" loop */ | |

i = start_bunzip(&bd, src_fd, outbuf + 2, len); | |

if (i == 0) { | |

while (1) { /* "Produce some output bytes" loop */ | |

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

if (i < 0) /* error? */ | |

break; | |

i = IOBUF_SIZE - i; /* number of bytes produced */ | |

if (i == 0) /* EOF? */ | |

break; | |

if (i != full_write(dst_fd, outbuf, i)) { | |

bb_error_msg("short write"); | |

i = RETVAL_SHORT_WRITE; | |

goto release_mem; | |

} | |

IF_DESKTOP(total_written += i;) | |

} | |

} | |

if (i != RETVAL_LAST_BLOCK) { | |

bb_error_msg("bunzip error %d", i); | |

break; | |

} | |

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

bb_error_msg("CRC error"); | |

break; | |

} | |

/* Successfully unpacked one BZ stream */ | |

i = RETVAL_OK; | |

/* Do we have "BZ..." after last processed byte? | |

* pbzip2 (parallelized bzip2) produces such files. | |

*/ | |

len = bd->inbufCount - bd->inbufPos; | |

memcpy(outbuf, &bd->inbuf[bd->inbufPos], len); | |

if (len < 2) { | |

if (safe_read(src_fd, outbuf + len, 2 - len) != 2 - len) | |

break; | |

len = 2; | |

} | |

if (*(uint16_t*)outbuf != BZIP2_MAGIC) /* "BZ"? */ | |

break; | |

dealloc_bunzip(bd); | |

len -= 2; | |

} | |

release_mem: | |

dealloc_bunzip(bd); | |

free(outbuf); | |

return i ? i : IF_DESKTOP(total_written) + 0; | |

} | |

IF_DESKTOP(long long) int FAST_FUNC | |

unpack_bz2_stream_prime(int src_fd, int dst_fd) | |

{ | |

uint16_t magic2; | |

xread(src_fd, &magic2, 2); | |

if (magic2 != BZIP2_MAGIC) { | |

bb_error_msg_and_die("invalid magic"); | |

} | |

return unpack_bz2_stream(src_fd, dst_fd); | |

} | |

#ifdef TESTING | |

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" | |

}; | |

/* Dumb little test thing, decompress stdin to stdout */ | |

int main(int argc, char **argv) | |

{ | |

int i; | |

char c; | |

int i = unpack_bz2_stream_prime(0, 1); | |

if (i < 0) | |

fprintf(stderr, "%s\n", bunzip_errors[-i]); | |

else if (read(STDIN_FILENO, &c, 1)) | |

fprintf(stderr, "Trailing garbage ignored\n"); | |

return -i; | |

} | |

#endif |