initial commit

Manifest.txt

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+lib/mimemagic.rb
+lib/mimemagic_tables.rb
+test/test_mimemagic.rb
+script/freedesktop.org.xml
+script/generate-mime.rb
+Rakefile
+README

README

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+MimeMagic is a library to detect the mime type of a file by extension or by content.
+
+Usage
+=====
+
+   require 'mimemagic'
+   MimeMagic.by_extension('html').text?
+   MimeMagic.by_extension('.html').child_of? 'text/plain'
+   MimeMagic.by_magic(File.open('test.html'))
+   etc...
+
+Authors
+=======
+
+Daniel Mendler

Rakefile

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+require 'hoe'
+
+$:.unshift 'lib'
+require 'mimemagic'
+
+Hoe.new 'mimemagic', MimeMagic::VERSION do |mimemagic|
+  mimemagic.developer 'Daniel Mendler', 'mail@daniel-mendler.de'
+  mimemagic.summary = 'Mime detection by extension or content'
+end
+

lib/mimemagic.rb

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+require 'mimemagic_tables'
+require 'stringio'
+
+# Mime type detection
+class MimeMagic
+  VERSION = '0.1'
+
+  attr_reader :type, :mediatype, :subtype
+
+  # Mime type by type string
+  def initialize(type)
+    @type      = type
+    @mediatype = @type.split('/')[0]
+    @subtype   = @type.split('/')[1]
+  end
+
+  # Add custom mime type. You have to
+  # specify the type, a string list of file extensions,
+  # a string list of parent mime types and an optional
+  # detector block for magic detection.
+  def self.add(type, extensions, parents, *magics)
+    TYPES[type] = [extensions, parents, block_given? ? proc(&block) : nil]
+    extensions.each do |ext|
+      EXTENSIONS[ext] = type
+    end
+    MAGIC.unshift [type, magics] if magics
+  end
+
+  # Returns true if type is a text format
+  def text?
+    child_of? 'text/plain'
+  end
+
+  # Returns true if type is child of parent type
+  def child_of?(parent)
+    child?(type, parent)
+  end
+
+  # Get string list of file extensions
+  def extensions
+    TYPES.key?(type) ? TYPES[type][0] : []
+  end
+
+  # Lookup mime type by file extension
+  def self.by_extension(ext)
+    ext = ext.downcase
+    mime = EXTENSIONS[ext] || (ext[0..0] == '.' && EXTENSIONS[ext[1..-1]])
+    mime ? new(mime) : nil
+  end
+
+  # Lookup mime type by magic content analysis
+  # That could be slow
+  def self.by_magic(content)
+    io = content.respond_to?(:seek) ? content : StringIO.new(content.to_s, 'rb')
+    mime = MAGIC.find {|type, matches| magic_match(io, matches) }
+    mime ? new(mime[0]) : nil
+  end
+
+  # Return type as string
+  def to_s
+    type
+  end
+
+  # Allow comparison with string
+  def ==(x)
+    type == x.to_s
+  end
+
+  private
+
+  def child?(child, parent)
+    return true if child == parent
+    TYPES.key?(child) ? TYPES[child][1].any? {|p| child?(p, parent) } : false
+  end
+
+  def self.magic_match(io, matches)
+    matches.any? do |offset, value, children|
+      if Range === offset
+        io.seek(offset.begin)
+        match = io.read(offset.end - offset.begin + value.length).include?(value)
+      else
+        io.seek(offset)
+        match = value == io.read(value.length)
+      end
+      match && (!children || magic_match(io, children))
+    end
+  rescue
+    false
+  end
+end