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# frozen_string_literal: true
# Code in this file adapted from the mimemagic gem, released under the MIT License.
# Copyright (c) 2011 Daniel Mendler. Available at https://github.com/mimemagicrb/mimemagic.
require 'marcel/tables'
require 'stringio'
module Marcel
# Mime type detection
class Magic
attr_reader :type, :mediatype, :subtype
# Mime type by type string
def initialize(type)
@type = type
@mediatype, @subtype = type.split('/', 2)
end
# Add custom mime type. Arguments:
# * <i>type</i>: Mime type
# * <i>options</i>: Options hash
#
# Option keys:
# * <i>:extensions</i>: String list or single string of file extensions
# * <i>:parents</i>: String list or single string of parent mime types
# * <i>:magic</i>: Mime magic specification
# * <i>:comment</i>: Comment string
def self.add(type, options)
extensions = [options[:extensions]].flatten.compact
TYPE_EXTS[type] = extensions
parents = [options[:parents]].flatten.compact
TYPE_PARENTS[type] = parents unless parents.empty?
extensions.each {|ext| EXTENSIONS[ext] = type }
MAGIC.unshift [type, options[:magic]] if options[:magic]
end
# Removes a mime type from the dictionary. You might want to do this if
# you're seeing impossible conflicts (for instance, application/x-gmc-link).
# * <i>type</i>: The mime type to remove. All associated extensions and magic are removed too.
def self.remove(type)
EXTENSIONS.delete_if {|ext, t| t == type }
MAGIC.delete_if {|t, m| t == type }
TYPE_EXTS.delete(type)
TYPE_PARENTS.delete(type)
end
# Returns true if type is a text format
def text?; mediatype == 'text' || child_of?('text/plain'); end
# Mediatype shortcuts
def image?; mediatype == 'image'; end
def audio?; mediatype == 'audio'; end
def video?; mediatype == 'video'; end
# Returns true if type is child of parent type
def child_of?(parent)
self.class.child?(type, parent)
end
# Get string list of file extensions
def extensions
TYPE_EXTS[type] || []
end
# Get mime comment
def comment
nil # deprecated
end
# Lookup mime type by file extension
def self.by_extension(ext)
ext = ext.to_s.downcase
mime = ext[0..0] == '.' ? EXTENSIONS[ext[1..-1]] : EXTENSIONS[ext]
mime && new(mime)
end
# Lookup mime type by filename
def self.by_path(path)
by_extension(File.extname(path))
end
# Lookup mime type by magic content analysis.
# This is a slow operation.
def self.by_magic(io)
mime = magic_match(io, :find)
mime && new(mime[0])
end
# Lookup all mime types by magic content analysis.
# This is a slower operation.
def self.all_by_magic(io)
magic_match(io, :select).map { |mime| new(mime[0]) }
end
# Return type as string
def to_s
type
end
# Allow comparison with string
def eql?(other)
type == other.to_s
end
def hash
type.hash
end
alias == eql?
def self.child?(child, parent)
child == parent || TYPE_PARENTS[child]&.any? {|p| child?(p, parent) }
end
def self.magic_match(io, method)
return magic_match(StringIO.new(io.to_s), method) unless io.respond_to?(:read)
io.binmode if io.respond_to?(:binmode)
io.set_encoding(Encoding::BINARY) if io.respond_to?(:set_encoding)
buffer = "".encode(Encoding::BINARY)
MAGIC.send(method) { |type, matches| magic_match_io(io, matches, buffer) }
end
def self.magic_match_io(io, matches, buffer)
matches.any? do |offset, value, children|
match =
if value
if Range === offset
io.read(offset.begin, buffer)
x = io.read(offset.end - offset.begin + value.bytesize, buffer)
x && x.include?(value)
else
io.read(offset, buffer)
io.read(value.bytesize, buffer) == value
end
end
io.rewind
match && (!children || magic_match_io(io, children, buffer))
end
end
private_class_method :magic_match, :magic_match_io
end
end
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