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|
# frozen_string_literal: true
require "mini_mime/version"
require "thread"
module MiniMime
def self.lookup_by_filename(filename)
Db.lookup_by_filename(filename)
end
def self.lookup_by_extension(extension)
Db.lookup_by_extension(extension)
end
def self.lookup_by_content_type(mime)
Db.lookup_by_content_type(mime)
end
module Configuration
class << self
attr_accessor :ext_db_path
attr_accessor :content_type_db_path
end
self.ext_db_path = File.expand_path("../db/ext_mime.db", __FILE__)
self.content_type_db_path = File.expand_path("../db/content_type_mime.db", __FILE__)
end
class Info
BINARY_ENCODINGS = %w(base64 8bit)
attr_accessor :extension, :content_type, :encoding
def initialize(buffer)
@extension, @content_type, @encoding = buffer.split(/\s+/).map!(&:freeze)
end
def [](idx)
if idx == 0
@extension
elsif idx == 1
@content_type
elsif idx == 2
@encoding
end
end
def binary?
BINARY_ENCODINGS.include?(encoding)
end
end
class Db
def self.lookup_by_filename(filename)
extension = File.extname(filename)
return if extension.empty?
extension = extension[1..-1]
lookup_by_extension(extension)
end
def self.lookup_by_extension(extension)
@db ||= new
@db.lookup_by_extension(extension) ||
@db.lookup_by_extension(extension.downcase)
end
def self.lookup_by_content_type(content_type)
@db ||= new
@db.lookup_by_content_type(content_type)
end
class Cache
def initialize(size)
@size = size
@hash = {}
end
def []=(key, val)
rval = @hash[key] = val
@hash.shift if @hash.length > @size
rval
end
def fetch(key, &blk)
@hash.fetch(key, &blk)
end
end
if ::File.method_defined?(:pread)
PReadFile = ::File
else
# For Windows support
class PReadFile
def initialize(filename)
@mutex = Mutex.new
# We must open the file in binary mode
# otherwise Ruby's automatic line terminator
# translation will skew the row size
@file = ::File.open(filename, 'rb')
end
def readline(*args)
@file.readline(*args)
end
def pread(size, offset)
@mutex.synchronize do
@file.seek(offset, IO::SEEK_SET)
@file.read(size)
end
end
end
end
class RandomAccessDb
MAX_CACHED = 100
def initialize(path, sort_order)
@path = path
@file = PReadFile.new(@path)
@row_length = @file.readline("\n").length
@file_length = File.size(@path)
@rows = @file_length / @row_length
@hit_cache = Cache.new(MAX_CACHED)
@miss_cache = Cache.new(MAX_CACHED)
@sort_order = sort_order
end
def lookup(val)
@hit_cache.fetch(val) do
@miss_cache.fetch(val) do
data = lookup_uncached(val)
if data
@hit_cache[val] = data
else
@miss_cache[val] = nil
end
data
end
end
end
# lifted from marcandre/backports
def lookup_uncached(val)
from = 0
to = @rows - 1
result = nil
while from <= to do
midpoint = from + (to - from).div(2)
current = resolve(midpoint)
data = current[@sort_order]
if data > val
to = midpoint - 1
elsif data < val
from = midpoint + 1
else
result = current
break
end
end
result
end
def resolve(row)
Info.new(@file.pread(@row_length, row * @row_length).force_encoding(Encoding::UTF_8))
end
end
def initialize
@ext_db = RandomAccessDb.new(Configuration.ext_db_path, 0)
@content_type_db = RandomAccessDb.new(Configuration.content_type_db_path, 1)
end
def lookup_by_extension(extension)
@ext_db.lookup(extension)
end
def lookup_by_content_type(content_type)
@content_type_db.lookup(content_type)
end
end
end
|
