Class: String

Inherits:

Object

Object
String

Defined in:: lib/sixarm_ruby_magic_number_type/string.rb

Overview

Please see README

Constant Summary collapse

MagicNumberTypeHash = We implement magic number type by using a lookup hash. This is fast enough for our needs; it could be optimized. The key is a string that encodes the first bits. The value is a symbol that indicates the magic type. See: - IO#magic_number_type - File.magic_number_type Quirks: - JPEG adjustment: - Some cameras put JPEG Exif data in bytes 3 & 4, so we only check the first two bytes of a JPEG. - TIFF has two possible matches: - II.. Intel little ending ("II2A00") - MM.. Motorola big endian ("MM002A") TODO change from hash implementation to binary tree

{
  "<!doctyp" => :html,
  "<html" => :html,
  "<?xml" => :xml,
  "<MakerFile" => :adobe_framemaker,
  "BC" => :bitcode,
  "BM" => :bitmap,
  "BZ" => :bzip,
  "SIMPLE"=> :fits,
  "GIF8" => :gif,
  "GKSM" => :gks,
  ["01DA"].pack('H*') => :iris_rgb,
  ["F10040BB"].pack('H*') => :itc,
  ["FFD8"].pack('H*') => :jpeg,
  "IIN1" => :niff,
  "MThd" => :midi,
  "%PDF" => :pdf,
  "VIEW" => :pm,
  ["89504E470D0A1A0A"].pack('H*') => :png,
  "Y" + ["A6"].pack('H*') + "j" + ["95"].pack('H*') => :sun_rasterfile,
  "II" + ["2A00"].pack('H*') => :tiff,  # II means Intel format, then 42 little-endian
  "MM" + ["002A"].pack('H*') => :tiff,  # MM means Motorola format, then 42 big-endian
  "gimp xcf" => :gimp_xcf,
  "#FIG" => :xfig,
  "/* XPM */" => :xpm,
  ["1F9D"].pack('H*') => :compress,
  ["1F8B"].pack('H*') => :gzip,
  "\x1F\xA0" => :tar_file_using_lzh_compression,
  "PK\x03\x04" => :pkzip,
  "7Z\xBC\xAF\x27\x1C" => :seven_zip,
  "MZ" => :dos_os2_windows_executable,
  ".ELF" => :unix_elf,
  "\x99\x00" => :pgp_public_ring,
  "\x95\x01" => :pgp_security_ring,
  "\x95\x00" => :pgp_security_ring,
  "\xA6\x00" => :pgp_encrypted_data,
  "\xD0\xCF\x11\xE0" => :docfile,
  #TODO matroska seems to have multiple magic file types-- diagnose and fix
  #"\x1a\x45\xdf\xa3\xa3\x42\x86\x81\x01\x42\xf7\x81\x01\x42\xf2\x81\x04\x42\xf3\x81\x08\x42\x82\x88matroska" => :matroska_stream,
  ".RTS COMPRESSED IMAGE" => :runtime_software_disk_image,
  "WS" => :wordstar_document,
  "!BDN" => :microsoft_outlook_personal_folder_file,
  "# Disk Descripto" => :vmware_disk_description,
  "# Microsoft Developer Studio" => :microsoft_developer_studio,
  "#!AMR" => :adaptive_multi_rate,
  "#?RADIANCE." => :radiance_high_dynamic_range_image_file,
  "%!PS-Adobe-3.0 EPSF-3.0" => :encapsulated_postscript,
  "8BPS" => :adobe_photoshop,
  "\x00\xBF" => :adobe_flash_shared_object,  # Typically a flash cookie
  "\x00\x00\x00\x14ftypisom" => :iso_base_media,  # ISO Base Media file (MPEG-4) v1
  "\x00\x00\x00\x14ftypqt" => :quicktime_movie,
  "\x00\x00\x00\x14fty3gp5" => :mpeg4_video,
  "\x00\x00\x00\x14ftymp42" => :mpeg4_video_quicktime,
  "\x00\x00\x00\x14ftyM4A" => :app_lossless_audio_codec,
  "\x00\x01\x00\x00MYISAM DATABASE" => :msisam_database,  # e.g. Microsoft Money
  "\x00\x01\x00\x00Standard ACE DB" => :microsoft_access_ace_db,
  "\x00\x01\x00\x00Standard Jet DB" => :microsoft_access_jet_db,
  "\x00\x01BA" => :palm_address_book,
  "\x00\x01BD" => :palm_date_book,
  "\x01\x0F\x00\x00" => :microsoft_sql_server_2000,
  "(This file must be converted with BinHex" => :binhex,
  "***  Installation Started" => :symantec_wise_installer_log_file,
  ".REC" => :realplayer_video,
  ".RMF" => :realplayer_media,
  "01ORDNANCE SURVEY" => :national_transfer_format_map,
  "\x31\xBE" => :microsoft_write,
  "\x32\xBE" => :microsoft_write,
  "4" + ["CDB2A1"].pack('H*') => :tcpdump,
  ":VERSION" => :surfplan_kite_project,
  "AC10" => :autocad,
  ".snd" => :sun_microsystems_law_audio_file,
  # Short ones below that would mask longer ones above
  "\x23\x21" => :shebang,
  "%!" => :postscript
}

MagicNumberTypeMaxLength = Longest key

Instance Method Summary collapse

#magic_number_type ⇒ Object

Detect the data type by checking various “magic number” conventions for the introductory bytes of a data stream.

Instance Method Details

#magic_number_type ⇒ `Object`

Detect the data type by checking various “magic number” conventions for the introductory bytes of a data stream

Return the “magic number” as a symbol:

- :bitmap = Bitmap image file, typical extension ".bmp"
- :gzip = Unix GZIP compressed data, typical extension ".gz"
- :postscript = Postscript pages, typical extension ".ps"

Return nil if there’s no match for any known magic number.

Examples:

"BM".magic_number_type => :bitmap
"GIF8".magic_numer_type => :gif
"\xa6\x00".magic_number_type => :pgp_encrypted_data

TODO change from hash implementation to binary tree