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EDIT :: tar_reader.rb

# -*- coding: utf-8 -*- #-- # Copyright (C) 2004 Mauricio Julio Fernández Pradier # See LICENSE.txt for additional licensing information. #++ ## # TarReader reads tar files and allows iteration over their items class Gem::Package::TarReader include Enumerable ## # Raised if the tar IO is not seekable class UnexpectedEOF < StandardError; end ## # Creates a new TarReader on +io+ and yields it to the block, if given. def self.new(io) reader = super return reader unless block_given? begin yield reader ensure reader.close end nil end ## # Creates a new tar file reader on +io+ which needs to respond to #pos, # #eof?, #read, #getc and #pos= def initialize(io) @io = io @init_pos = io.pos end ## # Close the tar file def close end ## # Iterates over files in the tarball yielding each entry def each return enum_for __method__ unless block_given? until @io.eof? do header = Gem::Package::TarHeader.from @io return if header.empty? entry = Gem::Package::TarReader::Entry.new header, @io size = entry.header.size yield entry skip = (512 - (size % 512)) % 512 pending = size - entry.bytes_read begin # avoid reading... @io.seek pending, IO::SEEK_CUR pending = 0 rescue Errno::EINVAL, NameError while pending > 0 do bytes_read = @io.read([pending, 4096].min).size raise UnexpectedEOF if @io.eof? pending -= bytes_read end end @io.read skip # discard trailing zeros # make sure nobody can use #read, #getc or #rewind anymore entry.close end end alias each_entry each ## # NOTE: Do not call #rewind during #each def rewind if @init_pos == 0 then raise Gem::Package::NonSeekableIO unless @io.respond_to? :rewind @io.rewind else raise Gem::Package::NonSeekableIO unless @io.respond_to? :pos= @io.pos = @init_pos end end ## # Seeks through the tar file until it finds the +entry+ with +name+ and # yields it. Rewinds the tar file to the beginning when the block # terminates. def seek name # :yields: entry found = find do |entry| entry.full_name == name end return unless found return yield found ensure rewind end end require 'rubygems/package/tar_reader/entry'

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