Class: Omnizip::Formats::Zip::CentralDirectoryHeader

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

Overview

ZIP Central Directory File Header

Constant Summary

Constants included from Constants

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

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(signature: CENTRAL_DIRECTORY_SIGNATURE, version_made_by: VERSION_MADE_BY_UNIX, version_needed: VERSION_DEFAULT, flags: 0, compression_method: COMPRESSION_STORE, last_mod_time: 0, last_mod_date: 0, crc32: 0, compressed_size: 0, uncompressed_size: 0, filename_length: 0, extra_field_length: 0, comment_length: 0, disk_number_start: 0, internal_attributes: 0, external_attributes: 0, local_header_offset: 0, filename: "", extra_field: "", comment: "") ⇒ CentralDirectoryHeader

Returns a new instance of CentralDirectoryHeader.



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# File 'lib/omnizip/formats/zip/central_directory_header.rb', line 18

def initialize(
  signature: CENTRAL_DIRECTORY_SIGNATURE,
  version_made_by: VERSION_MADE_BY_UNIX,
  version_needed: VERSION_DEFAULT,
  flags: 0,
  compression_method: COMPRESSION_STORE,
  last_mod_time: 0,
  last_mod_date: 0,
  crc32: 0,
  compressed_size: 0,
  uncompressed_size: 0,
  filename_length: 0,
  extra_field_length: 0,
  comment_length: 0,
  disk_number_start: 0,
  internal_attributes: 0,
  external_attributes: 0,
  local_header_offset: 0,
  filename: "",
  extra_field: "",
  comment: ""
)
  @signature = signature
  @version_made_by = version_made_by
  @version_needed = version_needed
  @flags = flags
  @compression_method = compression_method
  @last_mod_time = last_mod_time
  @last_mod_date = last_mod_date
  @crc32 = crc32
  @compressed_size = compressed_size
  @uncompressed_size = uncompressed_size
  @filename_length = filename_length
  @extra_field_length = extra_field_length
  @comment_length = comment_length
  @disk_number_start = disk_number_start
  @internal_attributes = internal_attributes
  @external_attributes = external_attributes
  @local_header_offset = local_header_offset
  @filename = filename
  @extra_field = extra_field
  @comment = comment
end

Instance Attribute Details

#cached_original_data ⇒ Object

Returns the value of attribute cached_original_data.



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

def cached_original_data
  @cached_original_data
end

#comment ⇒ Object

Returns the value of attribute comment.



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

def comment_length
  @comment_length
end

#compressed_size ⇒ Object

Returns the value of attribute compressed_size.



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

def compressed_size
  @compressed_size
end

#compression_method ⇒ Object

Returns the value of attribute compression_method.



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

def compression_method
  @compression_method
end

#crc32 ⇒ Object

Returns the value of attribute crc32.



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

def crc32
  @crc32
end

#disk_number_start ⇒ Object

Returns the value of attribute disk_number_start.



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

def disk_number_start
  @disk_number_start
end

#external_attributes ⇒ Object

Returns the value of attribute external_attributes.



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

def external_attributes
  @external_attributes
end

#extra_field ⇒ Object

Returns the value of attribute extra_field.



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

def extra_field
  @extra_field
end

#extra_field_length ⇒ Object

Returns the value of attribute extra_field_length.



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

def extra_field_length
  @extra_field_length
end

#filename ⇒ Object

Returns the value of attribute filename.



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

def filename
  @filename
end

#filename_length ⇒ Object

Returns the value of attribute filename_length.



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

def filename_length
  @filename_length
end

#flags ⇒ Object

Returns the value of attribute flags.



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

def flags
  @flags
end

#internal_attributes ⇒ Object

Returns the value of attribute internal_attributes.



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

def internal_attributes
  @internal_attributes
end

#last_mod_date ⇒ Object

Returns the value of attribute last_mod_date.



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

def last_mod_date
  @last_mod_date
end

#last_mod_time ⇒ Object

Returns the value of attribute last_mod_time.



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

def last_mod_time
  @last_mod_time
end

#local_header_offset ⇒ Object

Returns the value of attribute local_header_offset.



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

def local_header_offset
  @local_header_offset
end

#signature ⇒ Object

Returns the value of attribute signature.



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

def signature
  @signature
end

#uncompressed_size ⇒ Object

Returns the value of attribute uncompressed_size.



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

def uncompressed_size
  @uncompressed_size
end

#version_made_by ⇒ Object

Returns the value of attribute version_made_by.



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

def version_made_by
  @version_made_by
end

#version_needed ⇒ Object

Returns the value of attribute version_needed.



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

def version_needed
  @version_needed
end

Class Method Details

.from_binary(data) ⇒ Object

Parse from binary data



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# File 'lib/omnizip/formats/zip/central_directory_header.rb', line 140

def self.from_binary(data)
  signature, version_made_by, version_needed, flags,
  compression_method, last_mod_time, last_mod_date,
  crc32, compressed_size, uncompressed_size,
  filename_length, extra_field_length, comment_length,
  disk_number_start, internal_attributes,
  external_attributes, local_header_offset = data.unpack("VvvvvvvVVVvvvvvVV")

  unless signature == CENTRAL_DIRECTORY_SIGNATURE
    raise Omnizip::FormatError,
          "Invalid central directory signature"
  end

  offset = 46
  filename = data[offset, filename_length].force_encoding("UTF-8")
  offset += filename_length

  extra_field = data[offset, extra_field_length]
  offset += extra_field_length

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

  new(
    signature: signature,
    version_made_by: version_made_by,
    version_needed: version_needed,
    flags: flags,
    compression_method: compression_method,
    last_mod_time: last_mod_time,
    last_mod_date: last_mod_date,
    crc32: crc32,
    compressed_size: compressed_size,
    uncompressed_size: uncompressed_size,
    filename_length: filename_length,
    extra_field_length: extra_field_length,
    comment_length: comment_length,
    disk_number_start: disk_number_start,
    internal_attributes: internal_attributes,
    external_attributes: external_attributes,
    local_header_offset: local_header_offset,
    filename: filename,
    extra_field: extra_field,
    comment: comment,
  )
end

Instance Method Details

#directory? ⇒ Boolean

Check if this is a directory entry

Returns:

  • (Boolean) 


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# File 'lib/omnizip/formats/zip/central_directory_header.rb', line 63

def directory?
  filename.end_with?("/") ||
    external_attributes.anybits?(ATTR_DIRECTORY)
end

#encrypted? ⇒ Boolean

Check if entry is encrypted

Returns:

  • (Boolean) 


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# File 'lib/omnizip/formats/zip/central_directory_header.rb', line 77

def encrypted?
  flags.anybits?(FLAG_ENCRYPTED)
end

#header_size ⇒ Object

Size of the header in bytes



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# File 'lib/omnizip/formats/zip/central_directory_header.rb', line 187

def header_size
  46 + filename_length + extra_field_length + comment_length
end

#link_target ⇒ Object

Get link target from Unix extra field



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# File 'lib/omnizip/formats/zip/central_directory_header.rb', line 102

def link_target
  return nil unless symlink?

  unix_field = UnixExtraField.find_in_extra_field(extra_field)
  unix_field&.link_target
end

#symlink? ⇒ Boolean

Check if this is a symbolic link

Returns:

  • (Boolean) 


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# File 'lib/omnizip/formats/zip/central_directory_header.rb', line 97

def symlink?
  (unix_permissions & 0o170000) == 0o120000
end

#to_binary ⇒ Object

Serialize to binary format



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# File 'lib/omnizip/formats/zip/central_directory_header.rb', line 110

def to_binary
  @filename_length = filename.bytesize
  @extra_field_length = extra_field.bytesize
  @comment_length = comment.bytesize

  [
    signature,
    version_made_by,
    version_needed,
    flags,
    compression_method,
    last_mod_time,
    last_mod_date,
    crc32,
    compressed_size,
    uncompressed_size,
    filename_length,
    extra_field_length,
    comment_length,
    disk_number_start,
    internal_attributes,
    external_attributes,
    local_header_offset,
  ].pack("VvvvvvvVVVvvvvvVV") +
    filename.b +
    extra_field.b +
    comment.b
end

#unix_permissions ⇒ Object

Get Unix permissions from external attributes



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# File 'lib/omnizip/formats/zip/central_directory_header.rb', line 87

def unix_permissions
  (external_attributes >> 16) & 0xFFFF
end

#unix_permissions=(perms) ⇒ Object

Set Unix permissions in external attributes



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# File 'lib/omnizip/formats/zip/central_directory_header.rb', line 92

def unix_permissions=(perms)
  @external_attributes = (perms << 16) | (external_attributes & 0xFFFF)
end

#utf8? ⇒ Boolean

Check if UTF-8 encoding is used

Returns:

  • (Boolean) 


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# File 'lib/omnizip/formats/zip/central_directory_header.rb', line 82

def utf8?
  flags.anybits?(FLAG_UTF8)
end

#zip64? ⇒ Boolean

Check if ZIP64 format is needed

Returns:

  • (Boolean) 


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# File 'lib/omnizip/formats/zip/central_directory_header.rb', line 69

def zip64?
  compressed_size == ZIP64_LIMIT ||
    uncompressed_size == ZIP64_LIMIT ||
    local_header_offset == ZIP64_LIMIT ||
    disk_number_start == 0xFFFF
end