Class: Omnizip::Formats::Zip::EndOfCentralDirectory

Inherits:
Object
  • Object
show all
Includes:
Constants
Defined in:
lib/omnizip/formats/zip/end_of_central_directory.rb

Overview

ZIP End of Central Directory Record

Constant Summary

Constants included from Constants

Constants::ATTR_ARCHIVE, Constants::ATTR_DIRECTORY, Constants::CENTRAL_DIRECTORY_SIGNATURE, Constants::COMPRESSION_BZIP2, Constants::COMPRESSION_DEFLATE, Constants::COMPRESSION_DEFLATE64, Constants::COMPRESSION_IMPLODED, Constants::COMPRESSION_LZMA, Constants::COMPRESSION_PPMD, Constants::COMPRESSION_REDUCED_1, Constants::COMPRESSION_REDUCED_2, Constants::COMPRESSION_REDUCED_3, Constants::COMPRESSION_REDUCED_4, Constants::COMPRESSION_SHRUNK, Constants::COMPRESSION_STORE, Constants::COMPRESSION_ZSTANDARD, Constants::DATA_DESCRIPTOR_SIGNATURE, Constants::END_OF_CENTRAL_DIRECTORY_SIGNATURE, Constants::FLAG_DATA_DESCRIPTOR, Constants::FLAG_ENCRYPTED, Constants::FLAG_STRONG_ENCRYPTION, Constants::FLAG_UTF8, Constants::LOCAL_FILE_HEADER_SIGNATURE, Constants::MAX_COMMENT_LENGTH, Constants::UNIX_DIR_PERMISSIONS, Constants::UNIX_EXTRA_FIELD_TAG, Constants::UNIX_FILE_PERMISSIONS, Constants::UNIX_SYMLINK_PERMISSIONS, Constants::VERSION_BZIP2, Constants::VERSION_DEFAULT, Constants::VERSION_DEFLATE, Constants::VERSION_LZMA, Constants::VERSION_MADE_BY_UNIX, Constants::VERSION_MADE_BY_WINDOWS, Constants::VERSION_ZIP64, Constants::ZIP64_END_OF_CENTRAL_DIRECTORY_LOCATOR_SIGNATURE, Constants::ZIP64_END_OF_CENTRAL_DIRECTORY_SIGNATURE, Constants::ZIP64_EXTRA_FIELD_TAG, Constants::ZIP64_LIMIT

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(signature: END_OF_CENTRAL_DIRECTORY_SIGNATURE, disk_number: 0, disk_number_with_cd: 0, total_entries_this_disk: 0, total_entries: 0, central_directory_size: 0, central_directory_offset: 0, comment_length: 0, comment: "") ⇒ EndOfCentralDirectory

Returns a new instance of EndOfCentralDirectory.



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# File 'lib/omnizip/formats/zip/end_of_central_directory.rb', line 15

def initialize(
  signature: END_OF_CENTRAL_DIRECTORY_SIGNATURE,
  disk_number: 0,
  disk_number_with_cd: 0,
  total_entries_this_disk: 0,
  total_entries: 0,
  central_directory_size: 0,
  central_directory_offset: 0,
  comment_length: 0,
  comment: ""
)
  @signature = signature
  @disk_number = disk_number
  @disk_number_with_cd = disk_number_with_cd
  @total_entries_this_disk = total_entries_this_disk
  @total_entries = total_entries
  @central_directory_size = central_directory_size
  @central_directory_offset = central_directory_offset
  @comment_length = comment_length
  @comment = comment
end

Instance Attribute Details

#central_directory_offset ⇒ Object

Returns the value of attribute central_directory_offset.



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# File 'lib/omnizip/formats/zip/end_of_central_directory.rb', line 10

def central_directory_offset
  @central_directory_offset
end

#central_directory_size ⇒ Object

Returns the value of attribute central_directory_size.



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# File 'lib/omnizip/formats/zip/end_of_central_directory.rb', line 10

def central_directory_size
  @central_directory_size
end

#comment ⇒ Object

Returns the value of attribute comment.



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# File 'lib/omnizip/formats/zip/end_of_central_directory.rb', line 10

def comment
  @comment
end

#comment_length ⇒ Object

Returns the value of attribute comment_length.



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# File 'lib/omnizip/formats/zip/end_of_central_directory.rb', line 10

def comment_length
  @comment_length
end

#disk_number ⇒ Object

Returns the value of attribute disk_number.



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# File 'lib/omnizip/formats/zip/end_of_central_directory.rb', line 10

def disk_number
  @disk_number
end

#disk_number_with_cd ⇒ Object

Returns the value of attribute disk_number_with_cd.



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# File 'lib/omnizip/formats/zip/end_of_central_directory.rb', line 10

def disk_number_with_cd
  @disk_number_with_cd
end

#signature ⇒ Object

Returns the value of attribute signature.



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# File 'lib/omnizip/formats/zip/end_of_central_directory.rb', line 10

def signature
  @signature
end

#total_entries ⇒ Object

Returns the value of attribute total_entries.



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# File 'lib/omnizip/formats/zip/end_of_central_directory.rb', line 10

def total_entries
  @total_entries
end

#total_entries_this_disk ⇒ Object

Returns the value of attribute total_entries_this_disk.



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# File 'lib/omnizip/formats/zip/end_of_central_directory.rb', line 10

def total_entries_this_disk
  @total_entries_this_disk
end

Class Method Details

.find_in_file(io) ⇒ Object

Find EOCD record by scanning backwards from end of file

Raises:



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# File 'lib/omnizip/formats/zip/end_of_central_directory.rb', line 96

def self.find_in_file(io)
  # Start from the end and work backwards
  # EOCD is at least 22 bytes, can be up to 22 + MAX_COMMENT_LENGTH
  io.seek(0, ::IO::SEEK_END)
  file_size = io.pos

  # Start searching from the end
  max_comment_size = [file_size - 22, MAX_COMMENT_LENGTH].min
  search_start = [file_size - 22 - max_comment_size, 0].max

  io.seek(search_start, ::IO::SEEK_SET)
  buffer = io.read(file_size - search_start)

  # Search for EOCD signature from the end
  signature_bytes = [END_OF_CENTRAL_DIRECTORY_SIGNATURE].pack("V")

  (buffer.size - 22).downto(0) do |i|
    if buffer[i, 4] == signature_bytes
      # Found potential EOCD
      eocd_data = buffer[i..]
      comment_length = eocd_data[20, 2].unpack1("v")

      # Verify this is the actual EOCD by checking if comment length is reasonable
      # Some ZIP tools add trailing data, so we check if comment fits within remaining buffer
      if i + 22 + comment_length <= buffer.size
        return from_binary(eocd_data[0, 22 + comment_length])
      end
    end
  end

  raise Omnizip::FormatError,
        "Could not find End of Central Directory record"
end

.from_binary(data) ⇒ Object

Parse from binary data



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# File 'lib/omnizip/formats/zip/end_of_central_directory.rb', line 64

def self.from_binary(data)
  signature, disk_number, disk_number_with_cd,
  total_entries_this_disk, total_entries,
  central_directory_size, central_directory_offset,
  comment_length = data.unpack("VvvvvVVv")

  unless signature == END_OF_CENTRAL_DIRECTORY_SIGNATURE
    raise Omnizip::FormatError,
          "Invalid EOCD signature"
  end

  comment = data[22, comment_length].to_s.force_encoding("UTF-8")

  new(
    signature: signature,
    disk_number: disk_number,
    disk_number_with_cd: disk_number_with_cd,
    total_entries_this_disk: total_entries_this_disk,
    total_entries: total_entries,
    central_directory_size: central_directory_size,
    central_directory_offset: central_directory_offset,
    comment_length: comment_length,
    comment: comment,
  )
end

Instance Method Details

#record_size ⇒ Object

Size of the record in bytes



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# File 'lib/omnizip/formats/zip/end_of_central_directory.rb', line 91

def record_size
  22 + comment_length
end

#to_binary ⇒ Object

Serialize to binary format



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# File 'lib/omnizip/formats/zip/end_of_central_directory.rb', line 47

def to_binary
  @comment_length = comment.bytesize

  [
    signature,
    disk_number,
    disk_number_with_cd,
    total_entries_this_disk,
    total_entries,
    central_directory_size,
    central_directory_offset,
    comment_length,
  ].pack("VvvvvVVv") +
    comment.b
end

#zip64? ⇒ Boolean

Check if ZIP64 format is needed

Returns:

  • (Boolean) 


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# File 'lib/omnizip/formats/zip/end_of_central_directory.rb', line 38

def zip64?
  total_entries == 0xFFFF ||
    central_directory_size == ZIP64_LIMIT ||
    central_directory_offset == ZIP64_LIMIT ||
    disk_number == 0xFFFF ||
    disk_number_with_cd == 0xFFFF
end