Class: IOP::FTPFileReader

Inherits:
Object
  • Object
show all
Includes:
FTPFile, Feed
Defined in:
lib/iop/net/ftp.rb

Overview

Feed class to read file from FTP server.

This class an adapter for the standard Ruby Net::FTP class.

### Use case: retrieve file from FTP server and store it locally.

require 'iop/net/ftp'
( IOP::FTPFileReader.new('ftp.gnu.org', '/pub/README') | IOP::FileWriter.new('README') ).process!

Since:

  • 0.1

Instance Attribute Summary

Attributes included from Feed

#downstream

Instance Method Summary collapse

Methods included from Feed

#process, #|

Constructor Details

#initialize(ftp, file, size: nil, offset: nil, block_size: DEFAULT_BLOCK_SIZE, **options) ⇒ FTPFileReader

Creates class instance.

ftp can be either a String of Net::FTP instance. If it is a string a corresponding Net::FTP instance will be created with options passed to its constructor.

If ftp is a string, a created FTP connection is managed, e.g. it is closed after the process is complete, otherwise supplied object is left as is and no closing is performed. This allows to reuse FTP connection for a sequence of operations.

Refer to Net::FTP documentation for available options.

Parameters:

  • ftp (String, Net::FTP) —

    FTP server to connect to

  • file (String) —

    file name to process

  • size (Integer) (defaults to: nil) —

    total number of bytes to read; nil value instructs to read until end-of-data is reached

  • offset (Integer) (defaults to: nil) —

    offset in bytes from the stream start to seek to; nil value means no seeking is performed

  • block_size (Integer) (defaults to: DEFAULT_BLOCK_SIZE) —

    size of blocks to process data with

  • options (Hash) —

    extra keyword parameters passed to Net::FTP constructor

Since:

  • 0.1



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# File 'lib/iop/net/ftp.rb', line 87

def initialize(ftp, file, size: nil, offset: nil, block_size: DEFAULT_BLOCK_SIZE, **options)
  @block_size = size.nil? ? block_size : IOP.min(size, block_size)
  @left = @size = size
  @options = options
  @offset = offset
  @file = file
  @ftp = ftp
end

Instance Method Details

#process! ⇒ Object

Since:

  • 0.1



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# File 'lib/iop/net/ftp.rb', line 96

def process!
  setup
  begin
    # FTP logic taken from Net::FTP#retrbinary
    @io = transfercmd('RETR ' << @file, @offset)
    begin
      loop do
        read_size = @size.nil? ? @block_size : IOP.min(@left, @block_size)
        break if read_size.zero?
        data = @io.read(read_size)
        if data.nil?
          if @size.nil?
            break
          else
            raise EOFError, INSUFFICIENT_DATA
          end
        else
          unless @left.nil?
            @left -= data.size
            raise IOError, EXTRA_DATA if @left < 0
          end
          process(data) unless data.size.zero?
        end
      end
      process
      @io.shutdown(Socket::SHUT_WR)
      @io.read_timeout = 1
      @io.read
    ensure
      @io.close
    end
    voidresp
  ensure
    cleanup
  end
end