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