Class: Gem::Package::TarReader

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/rubygems/package/tar_reader.rb

Overview

TarReader reads tar files and allows iteration over their items

Defined Under Namespace

Classes: Entry, UnexpectedEOF

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(io) ⇒ TarReader

Creates a new tar file reader on io which needs to respond to #pos, #eof?, #read, #getc and #pos=



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# File 'lib/rubygems/package/tar_reader.rb', line 41

def initialize(io)
  @io = io
  @init_pos = io.pos
end

Class Method Details

.new(io) ⇒ Object

Creates a new TarReader on io and yields it to the block, if given.



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# File 'lib/rubygems/package/tar_reader.rb', line 23

def self.new(io)
  reader = super

  return reader unless block_given?

  begin
    yield reader
  ensure
    reader.close
  end

  nil
end

Instance Method Details

#close ⇒ Object

Close the tar file



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# File 'lib/rubygems/package/tar_reader.rb', line 49

def close
end

#each ⇒ Object Also known as: each_entry

Iterates over files in the tarball yielding each entry



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# File 'lib/rubygems/package/tar_reader.rb', line 55

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

#rewind ⇒ Object

NOTE: Do not call #rewind during #each



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# File 'lib/rubygems/package/tar_reader.rb', line 100

def rewind
  if @init_pos == 0
    @io.rewind
  else
    @io.pos = @init_pos
  end
end

#seek(name) ⇒ Object

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.



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# File 'lib/rubygems/package/tar_reader.rb', line 113

def seek(name) # :yields: entry
  found = find do |entry|
    entry.full_name == name
  end

  return unless found

  return yield found
ensure
  rewind
end