84 lines
1.6 KiB
Ruby
84 lines
1.6 KiB
Ruby
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# 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 TestFileWriter
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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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# 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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r=""
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current = 0
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@pattern.split("").each do |block|
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if off >= current && (off+len) < current + blocksize
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current += data(block, current)[
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current-off..(current+blocksize)-(off+len)
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]
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end
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current += @blocksize
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end
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r
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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(off, len) == read_original(off, 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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