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# -*- coding: utf-8 -*-
# frozen_string_literal: true
#--
# 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?
use_seek = @io.respond_to?(:seek)
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
if use_seek
begin
# avoid reading if the @io supports seeking
@io.seek pending, IO::SEEK_CUR
pending = 0
rescue Errno::EINVAL
end
end
# if seeking isn't supported or failed
while pending > 0 do
bytes_read = @io.read([pending, 4096].min).size
raise UnexpectedEOF if @io.eof?
pending -= bytes_read
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
@io.rewind
else
@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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