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61 lines
2.5 KiB
Ruby
61 lines
2.5 KiB
Ruby
module DebUtils
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def self.extract_deb(file, target)
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# extract_deb: unarchive .deb files
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# Usage: extract_deb(<file>, <target (optional)>)
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# file: a .deb archive file
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# target: (optional) a specified file to extract from archive, should be passed in regex or string
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#
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# Example:
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# extract_deb('example.deb', 'test.txt') # extract `test.txt` from example.deb
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# extract_deb('example.deb', /data\..*/) # extract files from example.deb with filenames matching the /data\..*/ regex
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# extract_deb('example.deb', /*/) # extract all files from example.deb
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#
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file_found = false
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src_file_io = File.open(file, 'rb')
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file_size = src_file_io.size
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# get first line of the given file, should be a signature string (`!<arch>\n`) if it is a valid deb file
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signature = src_file_io.gets
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abort 'Malformed archive :/'.lightred unless signature == "!<arch>\n"
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# process each file in archive
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while (line = src_file_io.gets)
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if line.chomp.empty? && (file_size == src_file_io.tell)
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# early return if trailing newline is detected
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break
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elsif line.chomp.empty?
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warn "Unexpected newline in offset #{src_file_io.tell}, ignoring...".yellow
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next
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end
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# read file meta
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name, _modtime, _uid, _gid, mode, size, end_char = \
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line.scan(/(.{16})(.{12})(.{6})(.{6})(.{8})(.{10})(.{1})/).flatten.map(&:strip)
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# remove slash suffix from filename (if any)
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# (a `.deb` ar archive does not support any directories, so we can confirm that all entries are normal files)
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name&.sub!(%r{/$}, '')
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# check ending byte
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abort 'Malformed archive :/'.lightred unless end_char == '`'
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# capture file in archive with given offset bytes (file size)
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file_content = src_file_io.read(size.to_i)
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# filter filename if a target file is specified
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if target.is_a?(String) && (name == target)
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# if target is passed as string, write matched file to filesyetem and exit function
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# write to filesystem
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return File.binwrite(name, file_content, perm: mode.to_i(8))
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elsif target.is_a?(Regexp) && name =~ (target)
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# if target is passed as regex, write matched file to filesyetem and continue
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# searching for another matched file until EOF
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# write to filesystem
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File.binwrite(name, file_content, perm: mode.to_i(8))
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file_found = true
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end
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end
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abort "Target #{target.inspect} not found in archive. :/".lightred unless file_found
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end
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end
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