Method: ZipTricks::ZipWriter#write_end_of_central_directory

Defined in:

lib/zip_tricks/zip_writer.rb

#write_end_of_central_directory(io:, start_of_central_directory_location:, central_directory_size:, num_files_in_archive:, comment: ZIP_TRICKS_COMMENT) ⇒ void

This method returns an undefined value.

Writes the "end of central directory record" (including the Zip6 salient bits if necessary)

Parameters:

• io (#<<) —

  the buffer to write the central directory to.

• start_of_central_directory_location (Fixnum) —

  byte offset of the start of central directory form the beginning of ZIP file

• central_directory_size (Fixnum) —

  the size of the central directory (only file headers) in bytes

• num_files_in_archive (Fixnum) —

  How many files the archive contains

• comment (String) (defaults to: ZIP_TRICKS_COMMENT) —

  the comment for the archive (defaults to ZIP_TRICKS_COMMENT)

# File 'lib/zip_tricks/zip_writer.rb', line 253

def write_end_of_central_directory(io:, start_of_central_directory_location:, central_directory_size:, num_files_in_archive:, comment: ZIP_TRICKS_COMMENT)
  zip64_eocdr_offset = start_of_central_directory_location + central_directory_size

  zip64_required = central_directory_size > FOUR_BYTE_MAX_UINT ||
                   start_of_central_directory_location > FOUR_BYTE_MAX_UINT ||
                   zip64_eocdr_offset > FOUR_BYTE_MAX_UINT ||
                   num_files_in_archive > TWO_BYTE_MAX_UINT

  # Then, if zip64 is used
  if zip64_required
    # [zip64 end of central directory record]
    # zip64 end of central dir
    io << [0x06064b50].pack(C_UINT4)                           # signature                       4 bytes  (0x06064b50)
    io << [44].pack(C_UINT8)                                  # size of zip64 end of central
    # directory record                8 bytes
    # (this is ex. the 12 bytes of the signature and the size value itself).
    # Without the extensible data sector (which we are not using)
    # it is always 44 bytes.
    io << MADE_BY_SIGNATURE                                # version made by                 2 bytes
    io << [VERSION_NEEDED_TO_EXTRACT_ZIP64].pack(C_UINT2)      # version needed to extract       2 bytes
    io << [0].pack(C_UINT4)                                    # number of this disk             4 bytes
    io << [0].pack(C_UINT4)                                    # number of the disk with the
    # start of the central directory  4 bytes
    io << [num_files_in_archive].pack(C_UINT8)                # total number of entries in the
    # central directory on this disk  8 bytes
    io << [num_files_in_archive].pack(C_UINT8)                # total number of entries in the
    # central directory               8 bytes
    io << [central_directory_size].pack(C_UINT8)              # size of the central directory   8 bytes
    # offset of start of central
    # directory with respect to
    io << [start_of_central_directory_location].pack(C_UINT8) # the starting disk number        8 bytes
    # zip64 extensible data sector    (variable size), blank for us

    # [zip64 end of central directory locator]
    io << [0x07064b50].pack(C_UINT4)                           # zip64 end of central dir locator
    # signature                       4 bytes  (0x07064b50)
    io << [0].pack(C_UINT4)                                    # number of the disk with the
    # start of the zip64 end of
    # central directory               4 bytes
    io << [zip64_eocdr_offset].pack(C_UINT8)                  # relative offset of the zip64
    # end of central directory record 8 bytes
    # (note: "relative" is actually "from the start of the file")
    io << [1].pack(C_UINT4)                                    # total number of disks           4 bytes
  end

  # Then the end of central directory record:
  io << [0x06054b50].pack(C_UINT4)                            # end of central dir signature     4 bytes  (0x06054b50)
  io << [0].pack(C_UINT2)                                     # number of this disk              2 bytes
  io << [0].pack(C_UINT2)                                     # number of the disk with the
  # start of the central directory 2 bytes

  if zip64_required # the number of entries will be read from the zip64 part of the central directory
    io << [TWO_BYTE_MAX_UINT].pack(C_UINT2)                   # total number of entries in the
    # central directory on this disk   2 bytes
    io << [TWO_BYTE_MAX_UINT].pack(C_UINT2)                   # total number of entries in
  # the central directory            2 bytes
  else
    io << [num_files_in_archive].pack(C_UINT2)                # total number of entries in the
    # central directory on this disk   2 bytes
    io << [num_files_in_archive].pack(C_UINT2)                # total number of entries in
    # the central directory            2 bytes
  end

  if zip64_required
    io << [FOUR_BYTE_MAX_UINT].pack(C_UINT4)                  # size of the central directory    4 bytes
    io << [FOUR_BYTE_MAX_UINT].pack(C_UINT4)                  # offset of start of central
  # directory with respect to
  # the starting disk number        4 bytes
  else
    io << [central_directory_size].pack(C_UINT4)              # size of the central directory    4 bytes
    io << [start_of_central_directory_location].pack(C_UINT4) # offset of start of central
    # directory with respect to
    # the starting disk number        4 bytes
  end
  io << [comment.bytesize].pack(C_UINT2)                      # .ZIP file comment length        2 bytes
  io << comment                                           # .ZIP file comment       (variable size)
end