eerste poging

ndsstrip/ndsstrip.rb

@@ -0,0 +1,111 @@
+#!/usr/bin/env ruby
+
+# $Id: ruby 1708 2006-02-24 10:09:22Z ward $
+# $URL$
+
+#
+# Copyright (c) 2007 Ward Wouts <ward@wouts.nl>
+#
+# Permission to use, copy, modify, and distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+#
+
+require 'getoptlong'
+
+def usage
+	puts <<EOT
+Usage: #{$0.sub(/.*\//, "")} [options]
+
+-h, --help			Show this message
+-s, --source <source>		Source file
+-t, --target <target>		Target file; default "<source>.trimmed"
+
+EOT
+	exit 1
+end
+
+def cmdline
+	options = Hash.new
+	begin
+		opts = GetoptLong.new(
+			[ "-s", "--source",	GetoptLong::REQUIRED_ARGUMENT ],
+			[ "-t", "--target",	GetoptLong::REQUIRED_ARGUMENT ],
+			[ "-h", "--help",	GetoptLong::NO_ARGUMENT ]
+		)
+		opts.quiet=true
+
+		opts.each do |opt, arg|
+			options[opt] = arg
+		end
+
+	rescue
+		print "#{$!}\n"
+		usage
+	end
+	if options["-h"]
+		usage
+	elsif options["-s"].nil?
+		usage
+	end
+	if options["-t"].nil?
+		options["-t"] = "#{options["-s"]}.trimmed"
+	end
+	return options
+end
+
+options = cmdline
+
+if FileTest.exists?(options["-t"])
+	puts "Target #{options["-t"]} already exists, not overwriting"
+	exit 1
+end
+
+if ! FileTest.readable?(options["-s"])
+	puts "Source #{options["-s"]} not readable, exiting"
+	exit 1
+end
+
+size = File.stat(options["-s"]).size
+trimpos = size
+
+# read last 1KB, check if all bytes are all te same
+sourcefile = File.new(options["-s"], "r")
+sourcefile.seek(-1024, IO::SEEK_END)
+block = sourcefile.read(1024)
+byte = block[0]
+block.each_byte{ |b|
+	if b != byte
+		puts "Last 1KB of #{source} doesn't appear to be filler"
+		exit 1
+	end
+}
+
+# scan backwards in blocks of 1KB until a byte differs
+while true do
+	sourcefile.seek(-2048, IO::SEEK_CUR)
+	block2 = sourcefile.read(1024)
+	if block2 != block
+		trimpos = sourcefile.pos
+		break
+	end
+end
+
+puts "Trimming to #{trimpos} bytes"
+
+# back to the beginning
+sourcefile.seek(0, IO::SEEK_SET)
+
+# open target
+targetfile = File.new(options["-t"], "w")
+while sourcefile.pos < trimpos do
+	targetfile.write(sourcefile.read(1024))
+end