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# frozen_string_literal: true
module TTFunk
class Table
# Digital Signature (`DSIG`) table.
class Dsig < Table
# Signature record.
class SignatureRecord
# Format of the signature.
# @return [Integer]
attr_reader :format
# Length of signature in bytes.
# @return [Integer]
attr_reader :length
# Offset to the signature block from the beginning of the table.
# @return [Integer]
attr_reader :offset
# Signature PKCS#7 packet.
# @return [String]
attr_reader :signature
# @param format [Integer]
# @param length [Integer]
# @param offset [Integer]
# @param signature [String]
def initialize(format, length, offset, signature)
@format = format
@length = length
@offset = offset
@signature = signature
end
end
# Version umber of this table.
# @return [Integer]
attr_reader :version
# Permission flags.
# @return [Integer]
attr_reader :flags
# Signature records.
# @return [Array<SignatureRecord>]
attr_reader :signatures
# Table tag.
TAG = 'DSIG'
# Encode table.
#
# **Note**: all signatures will be lost. This encodes an empty table
# regardless whether the supplied table contains any signtaures or not.
#
# @param dsig [TTFunk::Table::Dsig]
# @return [String]
def self.encode(dsig)
return unless dsig
# Don't attempt to re-sign or anything - just use dummy values.
# Since we're subsetting that should be permissible.
[dsig.version, 0, 0].pack('Nnn')
end
# Table tag.
#
# @return [String]
def tag
TAG
end
private
def parse!
@version, num_signatures, @flags = read(8, 'Nnn')
@signatures =
Array.new(num_signatures) {
format, length, sig_offset = read(12, 'N3')
signature =
parse_from(offset + sig_offset) {
_, _, sig_length = read(8, 'nnN')
read(sig_length, 'C*')
}
SignatureRecord.new(format, length, sig_offset, signature)
}
end
end
end
end
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