Class: Minitar::Reader

Inherits:

Object

• Object
• Minitar::Reader

Includes:

Enumerable

Defined in:

lib/minitar/reader.rb

Overview

The class that reads a tar format archive from a data stream. The data stream may be sequential or random access, but certain features only work with random access data streams.

Defined Under Namespace

Modules: InvalidEntryStream Classes: EntryStream

Class Method Summary

• .each_entry(io) ⇒ Object

  Iterates over each entry in the provided input.

• .open(io) ⇒ Object

  With no associated block, Reader::open is a synonym for Reader::new.

Instance Method Summary

• #close ⇒ Object
• #closed? ⇒ Boolean

  Returns false if the reader is open (it never closes).

• #each_entry ⇒ Object (also: #each)

  Iterates through each entry in the data stream.

• #initialize(io) ⇒ Reader constructor

  Creates and returns a new Reader object.

• #rewind ⇒ Object

  Resets the read pointer to the beginning of data stream.

Constructor Details

#initialize(io) ⇒ Reader

Creates and returns a new Reader object.

# File 'lib/minitar/reader.rb', line 198

def initialize(io)
  @io = io
  @init_pos = begin
    io.pos
  rescue
    nil
  end
end

Class Method Details

.each_entry(io) ⇒ Object

Iterates over each entry in the provided input. This wraps the common pattern of:

Minitar::Input.open(io) do |i|
  inp.each do |entry|
    # ...
  end
end

If a block is not provided, an enumerator will be created with the same behaviour.

call-seq:

Minitar::Reader.each_entry(io) -> enumerator
Minitar::Reader.each_entry(io) { |entry| block } -> obj

# File 'lib/minitar/reader.rb', line 187

def self.each_entry(io)
  return to_enum(__method__, io) unless block_given?

  Input.open(io) do |reader|
    reader.each_entry do |entry|
      yield entry
    end
  end
end

.open(io) ⇒ Object

With no associated block, Reader::open is a synonym for Reader::new. If the optional code block is given, it will be passed the new writer as an argument and the Reader object will automatically be closed when the block terminates. In this instance, Reader::open returns the value of the block.

# File 'lib/minitar/reader.rb', line 159

def self.open(io)
  reader = new(io)
  return reader unless block_given?

  # This exception context must remain, otherwise the stream closes on open
  # even if a block is not given.
  begin
    yield reader
  ensure
    reader.close
  end
end

Instance Method Details

#close ⇒ Object

# File 'lib/minitar/reader.rb', line 278

def close
end

#closed? ⇒ Boolean

Returns false if the reader is open (it never closes).

Returns:

• (Boolean)

# File 'lib/minitar/reader.rb', line 274

def closed?
  false
end

#each_entry ⇒ Object Also known as: each

Iterates through each entry in the data stream.

# File 'lib/minitar/reader.rb', line 225

def each_entry
  return to_enum unless block_given?

  loop do
    return if @io.eof?

    header = Minitar::PosixHeader.from_stream(@io)
    raise Minitar::InvalidTarStream unless header.valid?
    return if header.empty?

    raise Minitar::InvalidTarStream if header.size < 0

    if header.long_name?
      name_block = (header.size / 512.0).ceil * 512

      name = @io.read(name_block).rstrip
      header = PosixHeader.from_stream(@io)

      return if header.empty?
      header.name = name
    end

    entry = EntryStream.new(header, @io)
    size = entry.size

    yield entry

    skip = (512 - (size % 512)) % 512

    if Minitar.seekable?(@io, :seek)
      # avoid reading...
      @io.seek(size - entry.bytes_read, IO::SEEK_CUR)
    else
      pending = size - entry.bytes_read
      while pending > 0
        bread = @io.read([pending, 4096].min).bytesize
        raise UnexpectedEOF if @io.eof?
        pending -= bread
      end
    end

    @io.read(skip) # discard trailing zeros
    # make sure nobody can use #read, #getc or #rewind anymore
    entry.close
  end
end

#rewind ⇒ Object

Resets the read pointer to the beginning of data stream. Do not call this during a #each or #each_entry iteration. This only works with random access data streams that respond to #rewind and #pos.

# File 'lib/minitar/reader.rb', line 210

def rewind
  if @init_pos.zero?
    unless Minitar.seekable?(@io, :rewind)
      raise Minitar::NonSeekableStream
    end
    @io.rewind
  else
    unless Minitar.seekable?(@io, :pos=)
      raise Minitar::NonSeekableStream
    end
    @io.pos = @init_pos
  end
end