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|
# rm -r ~/.ruby_inline; ARCHFLAGS="-arch i386" ruby -r rubygems -r bzipread.rb \
# -e 'BzipReader.new.readBlock("../ga.wp.txt.bz2", 0)'
require 'rubygems'
require 'tempfile'
require 'inline'
require File.join(File.dirname(__FILE__), 'common')
BZ_MAX_BLOCK = 1024 * 900
class BzipReader
attr :offset
def debug(str)
$stderr.puts str
end
inline(:C) do |builder|
builder.add_compile_flags "-I../c -I. -lbz2"
builder.add_compile_flags "../c/bzipreader.c"
builder.add_compile_flags "../c/safe.c"
builder.prefix '
#include "bzipreader.h"
uint64_t readOffset;
'
['VALUE __decompressBlock(char *src, int srcLen) {
char dest[BZ_MAX_BLOCK];
uint32_t destLen = BZ_MAX_BLOCK;
int ret;
debug("ruby decompressing %d bytes", srcLen);
if((ret = decompressBlock(src, srcLen, dest, &destLen)) != BZ_OK)
fatal("couldn\'t decompress: bz error %d", ret);
return rb_str_new(dest, destLen);
}',
'VALUE __readBlock(char *file) {
FILE *in;
uint64_t realOffset;
VALUE str;
if(strlen(file) == 0) {
in = xfopen("/dev/stdin", "rb");
realOffset = 0;
} else {
in = xfopen(file, "rb");
realOffset = readOffset;
}
BitBuffer *bb = bbOfSize(BZ_MAX_BLOCK);
readOffset = fixedOffset(readBlock(in, realOffset, bb));
xfclose(in);
str = rb_str_new(bb->buff, bb->pos);
bbClose(bb);
return str;
}',
'void __setReadOffset(char *offset) {
readOffset = *((uint64_t *) offset);
}',
'VALUE __getReadOffset() {
return rb_str_new((char *) &readOffset, sizeof(uint64_t));
}',
'int __computeBoundaries(char *file) {
int size;
FILE *in = xfopen(file, "rb");
size = computeBoundaries(in);
xfclose(in);
return size;
}'].each {|c| builder.c c}
end
def uint64_to_char(num)
hi = num >> 32
lo = num & 0xffffffff
[lo, hi].pack('L2')
end
def char_to_uint64(char)
lo, hi = char.unpack('L2')
return lo + (hi << 32)
end
def initialize(file="")
if file.empty?
@useStdin = true
@buffered = ""
@eof = false
end
@file = file
@offset = 0
end
def getReadOffset
char_to_uint64(__getReadOffset)
end
def setReadOffset(num)
__setReadOffset(uint64_to_char(num))
end
def readNextBlock
# in bzipreader.c, readBlock reads more than it should -- to determine the end of a block,
# it reads the header for the subsequent block. If we're reading from a file, this is ok;
# we can seek back to where we want to be. But when reading from stdin, it's more awkward,
# and we have to buffer things
# TODO: use a named pipe
if @useStdin
if !@buffered or (@offset > 0 and @buffered.size < 40)
raise EOF
end
begin
@buffered += $stdin.read(BZ_MAX_BLOCK) if @buffered.size < BZ_MAX_BLOCK and !@eof
rescue TypeError
@eof = true
end
tempfile = Tempfile.new('bzipreader')
tempfile.write(@buffered)
tempfile.flush
setReadOffset(0)
block = __readBlock(tempfile.path)
offset = getReadOffset - 80
@offset += offset
bytes = (offset >> 3)
@buffered = @buffered[bytes..-1]
block
else
readBlock(@offset)
end
end
def readBlock(offset)
unless @useStdin
if File.size(@file) < (offset >> 3) + 80 + 40 # don't ask
raise EOF
end
end
setReadOffset(offset)
block = __readBlock(@file)
@offset = getReadOffset
block
end
def decompressBlock(str)
__decompressBlock(str, str.size)
end
def computeBoundaries
__computeBoundaries(@file)
end
def self.test(skip=0)
b = BzipReader.new('../ga.wp.txt.bz2')
skip.times do b.readNextBlock end
block = b.readNextBlock
block = b.decompressBlock(block)[0..100]
puts block
end
def self.stdin_test(skip = 0)
b = self.new
skip.times do b.readNextBlock end
blockNo = -1
while true
begin
offset = b.offset
block = b.readNextBlock
plaintext = b.decompressBlock(block)
$stderr.puts "#{blockNo += 1}\t#{offset}\t#{plaintext.gsub(/\n/, "\\n")[0..30]}"
$stdout.write plaintext
rescue EOF
$stderr.puts "EOF"
break
end
end
end
end
|
