125 lines
2.9 KiB
Ruby
125 lines
2.9 KiB
Ruby
# Noddy test class for writing files to disc in predictable patterns
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# in order to test FlexNBD.
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#
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class FileWriter
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def initialize(filename, blocksize)
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@fh = File.open(filename, 'w+')
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@blocksize = blocksize
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@pattern = ''
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end
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def size
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@blocksize * @pattern.split('').size
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end
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# We write in fixed block sizes, given by "blocksize"
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# _ means skip a block
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# 0 means write a block full of zeroes
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# f means write a block with the file offset packed every 4 bytes
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#
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def write(data)
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@pattern += data
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data.split('').each do |code|
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if code == '_'
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@fh.seek(@blocksize, IO::SEEK_CUR)
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else
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@fh.write(data(code))
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end
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end
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@fh.flush
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self
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end
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# Returns what the data ought to be at the given offset and length
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#
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def read_original(off, len)
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patterns = @pattern.split('')
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patterns.zip((0...patterns.length).to_a)
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.map do |blk, blk_off|
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data(blk, blk_off)
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end.join[off...(off + len)]
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end
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# Read what's actually in the file
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#
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def read(off, len)
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@fh.seek(off, IO::SEEK_SET)
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@fh.read(len)
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end
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def untouched?(offset, len)
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read(offset, len) == read_original(offset, len)
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end
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def close
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@fh.close
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nil
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end
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protected
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def data(code, at = @fh.tell)
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case code
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when '0', '_'
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"\0" * @blocksize
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when 'X'
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'X' * @blocksize
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when 'f'
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r = ''
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(@blocksize / 4).times do
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r += [at].pack('I')
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at += 4
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end
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r
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else
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raise "Unknown character '#{block}'"
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end
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end
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end
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if $PROGRAM_NAME == __FILE__
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require 'tempfile'
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require 'test/unit'
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class FileWriterTest < Test::Unit::TestCase
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def test_read_original_zeros
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Tempfile.open('test_read_original_zeros') do |tempfile|
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tempfile.close
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file = FileWriter.new(tempfile.path, 4096)
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file.write('0')
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assert_equal file.read(0, 4096), file.read_original(0, 4096)
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assert(file.untouched?(0, 4096), 'Untouched file was touched.')
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end
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end
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def test_read_original_offsets
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Tempfile.open('test_read_original_offsets') do |tempfile|
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tempfile.close
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file = FileWriter.new(tempfile.path, 4096)
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file.write('f')
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assert_equal file.read(0, 4096), file.read_original(0, 4096)
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assert(file.untouched?(0, 4096), 'Untouched file was touched.')
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end
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end
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def test_file_size
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Tempfile.open('test_file_size') do |tempfile|
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tempfile.close
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file = FileWriter.new(tempfile.path, 4096)
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file.write('f')
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assert_equal 4096, File.stat(tempfile.path).size
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end
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end
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def test_read_original_size
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Tempfile.open('test_read_original_offsets') do |tempfile|
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tempfile.close
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file = FileWriter.new(tempfile.path, 4)
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file.write('f' * 4)
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assert_equal 4, file.read_original(0, 4).length
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end
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end
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end
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end
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