Class: HttpZip::File

Inherits:
Object
  • Object
show all
Defined in:
lib/http_zip/file.rb

Overview

HttpZip reads ZIP-files over a HTTP connection that supports the Content-Range header. It is a helpful tool to extract single files from large HTTP archives without having to download them fully.

Resources regarding the ZIP file format: en.wikipedia.org/wiki/ZIP_(file_format) pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT

Instance Method Summary collapse

Constructor Details

#initialize(url) ⇒ File

Create a HttpZip file object that is located at url.

Parameters:

  • url (String) —

    where the file is hosted

Raises:



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# File 'lib/http_zip/file.rb', line 22

def initialize(url)
  @url = url
  @entries = nil
  @range_request = RangeRequest.new(url)
end

Instance Method Details

#entries ⇒ Object

Get all entries in the zip archive as an array of HttpZip::Entry. Makes up to 4 HTTP requests (HEAD, GET, GET, GET?)



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# File 'lib/http_zip/file.rb', line 30

def entries
  return @entries if @entries

  @entries = []
  last_bytes_of_file = @range_request.last(MAXIMUM_EOCD_AND_EOCD64_LOCATOR_SIZE)
  central_directory_bytes = get_central_directory(last_bytes_of_file)

  # iterate through central directory and spit out file entries
  until central_directory_bytes.empty?
    # get information about the current file entry
    file_header = HttpZip::Parser::CentralDirectoryFileHeader.new(central_directory_bytes)
    @entries << HttpZip::Entry.new(
      @url,
      file_header.file_name,
      file_header.header_offset,
      file_header.compressed_size,
      file_header.uncompressed_size
    )

    # skip ahead to next file entry
    central_directory_bytes = central_directory_bytes[(file_header.end_of_entry)..-1]
  end

  @entries
end