112 lines
2.5 KiB
Ruby
112 lines
2.5 KiB
Ruby
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#!/usr/bin/env ruby
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# $Id: ruby 1708 2006-02-24 10:09:22Z ward $
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# $URL$
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#
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# Copyright (c) 2007 Ward Wouts <ward@wouts.nl>
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#
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# Permission to use, copy, modify, and distribute this software for any
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# purpose with or without fee is hereby granted, provided that the above
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# copyright notice and this permission notice appear in all copies.
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#
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# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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#
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require 'getoptlong'
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def usage
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puts <<EOT
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Usage: #{$0.sub(/.*\//, "")} [options]
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-h, --help Show this message
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-s, --source <source> Source file
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-t, --target <target> Target file; default "<source>.trimmed"
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EOT
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exit 1
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end
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def cmdline
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options = Hash.new
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begin
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opts = GetoptLong.new(
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[ "-s", "--source", GetoptLong::REQUIRED_ARGUMENT ],
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[ "-t", "--target", GetoptLong::REQUIRED_ARGUMENT ],
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[ "-h", "--help", GetoptLong::NO_ARGUMENT ]
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)
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opts.quiet=true
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opts.each do |opt, arg|
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options[opt] = arg
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end
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rescue
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print "#{$!}\n"
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usage
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end
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if options["-h"]
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usage
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elsif options["-s"].nil?
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usage
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end
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if options["-t"].nil?
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options["-t"] = "#{options["-s"]}.trimmed"
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end
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return options
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end
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options = cmdline
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if FileTest.exists?(options["-t"])
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puts "Target #{options["-t"]} already exists, not overwriting"
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exit 1
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end
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if ! FileTest.readable?(options["-s"])
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puts "Source #{options["-s"]} not readable, exiting"
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exit 1
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end
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size = File.stat(options["-s"]).size
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trimpos = size
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# read last 1KB, check if all bytes are all te same
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sourcefile = File.new(options["-s"], "r")
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sourcefile.seek(-1024, IO::SEEK_END)
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block = sourcefile.read(1024)
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byte = block[0]
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block.each_byte{ |b|
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if b != byte
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puts "Last 1KB of #{source} doesn't appear to be filler"
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exit 1
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end
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}
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# scan backwards in blocks of 1KB until a byte differs
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while true do
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sourcefile.seek(-2048, IO::SEEK_CUR)
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block2 = sourcefile.read(1024)
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if block2 != block
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trimpos = sourcefile.pos
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break
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end
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end
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puts "Trimming to #{trimpos} bytes"
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# back to the beginning
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sourcefile.seek(0, IO::SEEK_SET)
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# open target
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targetfile = File.new(options["-t"], "w")
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while sourcefile.pos < trimpos do
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targetfile.write(sourcefile.read(1024))
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end
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