Only call hdiutil if it’s a bzip2 or zlib.

Library/Homebrew/unpack_strategy.rb

@@ -1,7 +1,31 @@
 module UnpackStrategy
-  # length of the longest regex (currently Tar)
-  MAX_MAGIC_NUMBER_LENGTH = 262
-  private_constant :MAX_MAGIC_NUMBER_LENGTH
+  module Magic
+    # length of the longest regex (currently Tar)
+    MAX_MAGIC_NUMBER_LENGTH = 262
+
+    refine Pathname do
+      def magic_number
+        @magic_number ||= if directory?
+          ""
+        else
+          binread(MAX_MAGIC_NUMBER_LENGTH) || ""
+        end
+      end
+
+      def file_type
+        @file_type ||= system_command("file", args: ["-b", self], print_stderr: false)
+                       .stdout.chomp
+      end
+
+      def zipinfo
+        @zipinfo ||= system_command("zipinfo", args: ["-1", self], print_stderr: false)
+                     .stdout
+                     .encode(Encoding::UTF_8, invalid: :replace)
+                     .split("\n")
+      end
+    end
+  end
+  private_constant :Magic
 
   def self.strategies
     @strategies ||= [
@@ -18,7 +42,6 @@ module UnpackStrategy
       Xz,
       Lzip,
       Executable,
-      Diff,
       Git,
       Mercurial,
       Subversion,
@@ -54,14 +77,8 @@ module UnpackStrategy
   end
 
   def self.from_path(path)
-    magic_number = if path.directory?
-      ""
-    else
-      File.binread(path, MAX_MAGIC_NUMBER_LENGTH) || ""
-    end
-
     strategy = strategies.detect do |s|
-      s.can_extract?(path: path, magic_number: magic_number)
+      s.can_extract?(path)
     end
 
     # This is so that bad files produce good error messages.
@@ -127,7 +144,6 @@ require "unpack_strategy/bzip2"
 require "unpack_strategy/cab"
 require "unpack_strategy/compress"
 require "unpack_strategy/cvs"
-require "unpack_strategy/diff"
 require "unpack_strategy/directory"
 require "unpack_strategy/dmg"
 require "unpack_strategy/executable"

Library/Homebrew/unpack_strategy/air.rb

@@ -2,7 +2,9 @@ module UnpackStrategy
   class Air
     include UnpackStrategy
 
-    def self.can_extract?(path:, magic_number:)
+    using Magic
+
+    def self.can_extract?(path)
       path.extname == ".air"
     end
 

Library/Homebrew/unpack_strategy/bazaar.rb

@@ -2,7 +2,9 @@ require_relative "directory"
 
 module UnpackStrategy
   class Bazaar < Directory
-    def self.can_extract?(path:, magic_number:)
+    using Magic
+
+    def self.can_extract?(path)
       super && (path/".bzr").directory?
     end
 

Library/Homebrew/unpack_strategy/bzip2.rb

@@ -2,8 +2,10 @@ module UnpackStrategy
   class Bzip2
     include UnpackStrategy
 
-    def self.can_extract?(path:, magic_number:)
-      magic_number.match?(/\ABZh/n)
+    using Magic
+
+    def self.can_extract?(path)
+      path.magic_number.match?(/\ABZh/n)
     end
 
     private

Library/Homebrew/unpack_strategy/cab.rb

@@ -2,8 +2,10 @@ module UnpackStrategy
   class Cab
     include UnpackStrategy
 
-    def self.can_extract?(path:, magic_number:)
-      magic_number.match?(/\AMSCF/n)
+    using Magic
+
+    def self.can_extract?(path)
+      path.magic_number.match?(/\AMSCF/n)
     end
 
     def extract_to_dir(unpack_dir, basename:, verbose:)

Library/Homebrew/unpack_strategy/compress.rb

@@ -2,8 +2,10 @@ require_relative "tar"
 
 module UnpackStrategy
   class Compress < Tar
-    def self.can_extract?(path:, magic_number:)
-      magic_number.match?(/\A\037\235/n)
+    using Magic
+
+    def self.can_extract?(path)
+      path.magic_number.match?(/\A\037\235/n)
     end
   end
 end

Library/Homebrew/unpack_strategy/cvs.rb

@@ -2,7 +2,9 @@ require_relative "directory"
 
 module UnpackStrategy
   class Cvs < Directory
-    def self.can_extract?(path:, magic_number:)
+    using Magic
+
+    def self.can_extract?(path)
       super && (path/"CVS").directory?
     end
   end

Library/Homebrew/unpack_strategy/diff.rb

@@ -1,9 +0,0 @@
-require_relative "uncompressed"
-
-module UnpackStrategy
-  class Diff < Uncompressed
-    def self.can_extract?(path:, magic_number:)
-      magic_number.match?(/\A---\040/n)
-    end
-  end
-end

Library/Homebrew/unpack_strategy/directory.rb

@@ -2,7 +2,9 @@ module UnpackStrategy
   class Directory
     include UnpackStrategy
 
-    def self.can_extract?(path:, magic_number:)
+    using Magic
+
+    def self.can_extract?(path)
       path.directory?
     end
 

Library/Homebrew/unpack_strategy/dmg.rb

@@ -4,6 +4,8 @@ module UnpackStrategy
   class Dmg
     include UnpackStrategy
 
+    using Magic
+
     module Bom
       DMG_METADATA = Set.new %w[
         .background
@@ -83,12 +85,21 @@ module UnpackStrategy
           end
 
           system_command! "ditto", args: ["--bom", bomfile.path, "--", path, unpack_dir]
+
+          FileUtils.chmod "u+w", Pathname.glob(unpack_dir/"**/*").reject(&:symlink?)
         end
       end
     end
     private_constant :Mount
 
-    def self.can_extract?(path:, magic_number:)
+    def self.can_extract?(path)
+      bzip2 = Bzip2.can_extract?(path)
+
+      zlib = path.magic_number.match?(/\A(\x78|\x08|\x18|\x28|\x38|\x48|\x58|\x68)/n) &&
+             (path.magic_number[0...2].unpack("S>").first % 31).zero?
+
+      return false unless bzip2 || zlib
+
       imageinfo = system_command("hdiutil",
                                  args: ["imageinfo", path],
                                  print_stderr: false).stdout

Library/Homebrew/unpack_strategy/executable.rb

@@ -2,8 +2,10 @@ require_relative "uncompressed"
 
 module UnpackStrategy
   class Executable < Uncompressed
-    def self.can_extract?(path:, magic_number:)
-      magic_number.match?(/\A#!\s*\S+/n)
+    using Magic
+
+    def self.can_extract?(path)
+      path.magic_number.match?(/\A#!\s*\S+/n)
     end
   end
 end

Library/Homebrew/unpack_strategy/fossil.rb

@@ -2,8 +2,10 @@ module UnpackStrategy
   class Fossil
     include UnpackStrategy
 
-    def self.can_extract?(path:, magic_number:)
-      return false unless magic_number.match?(/\ASQLite format 3\000/n)
+    using Magic
+
+    def self.can_extract?(path)
+      return false unless path.magic_number.match?(/\ASQLite format 3\000/n)
 
       # Fossil database is made up of artifacts, so the `artifact` table must exist.
       query = "select count(*) from sqlite_master where type = 'view' and name = 'artifact'"

Library/Homebrew/unpack_strategy/generic_unar.rb

@@ -2,7 +2,9 @@ module UnpackStrategy
   class GenericUnar
     include UnpackStrategy
 
-    def self.can_extract?(path:, magic_number:)
+    using Magic
+
+    def self.can_extract?(_path)
       false
     end
 

Library/Homebrew/unpack_strategy/git.rb

@@ -2,7 +2,9 @@ require_relative "directory"
 
 module UnpackStrategy
   class Git < Directory
-    def self.can_extract?(path:, magic_number:)
+    using Magic
+
+    def self.can_extract?(path)
       super && (path/".git").directory?
     end
   end

Library/Homebrew/unpack_strategy/gzip.rb

@@ -2,8 +2,10 @@ module UnpackStrategy
   class Gzip
     include UnpackStrategy
 
-    def self.can_extract?(path:, magic_number:)
-      magic_number.match?(/\A\037\213/n)
+    using Magic
+
+    def self.can_extract?(path)
+      path.magic_number.match?(/\A\037\213/n)
     end
 
     private

Library/Homebrew/unpack_strategy/jar.rb

@@ -2,14 +2,13 @@ require_relative "uncompressed"
 
 module UnpackStrategy
   class Jar < Uncompressed
-    def self.can_extract?(path:, magic_number:)
-      return false unless Zip.can_extract?(path: path, magic_number: magic_number)
+    using Magic
+
+    def self.can_extract?(path)
+      return false unless Zip.can_extract?(path)
 
       # Check further if the ZIP is a JAR/WAR.
-      out, = Open3.capture3("zipinfo", "-1", path)
-      out.encode(Encoding::UTF_8, invalid: :replace)
-         .split("\n")
-         .include?("META-INF/MANIFEST.MF")
+      path.zipinfo.include?("META-INF/MANIFEST.MF")
     end
   end
 end

Library/Homebrew/unpack_strategy/lha.rb

@@ -2,8 +2,10 @@ module UnpackStrategy
   class Lha
     include UnpackStrategy
 
-    def self.can_extract?(path:, magic_number:)
-      magic_number.match?(/\A..-(lh0|lh1|lz4|lz5|lzs|lh\\40|lhd|lh2|lh3|lh4|lh5)-/n)
+    using Magic
+
+    def self.can_extract?(path)
+      path.magic_number.match?(/\A..-(lh0|lh1|lz4|lz5|lzs|lh\\40|lhd|lh2|lh3|lh4|lh5)-/n)
     end
 
     def dependencies

Library/Homebrew/unpack_strategy/lua_rock.rb

@@ -2,14 +2,13 @@ require_relative "uncompressed"
 
 module UnpackStrategy
   class LuaRock < Uncompressed
-    def self.can_extract?(path:, magic_number:)
-      return false unless Zip.can_extract?(path: path, magic_number: magic_number)
+    using Magic
+
+    def self.can_extract?(path)
+      return false unless Zip.can_extract?(path)
 
       # Check further if the ZIP is a LuaRocks package.
-      out, = Open3.capture3("zipinfo", "-1", path)
-      out.encode(Encoding::UTF_8, invalid: :replace)
-         .split("\n")
-         .any? { |line| line.match?(%r{\A[^/]+.rockspec\Z}) }
+      path.zipinfo.grep(%r{\A[^/]+.rockspec\Z}).any?
     end
   end
 end

Library/Homebrew/unpack_strategy/lzip.rb

@@ -2,8 +2,10 @@ module UnpackStrategy
   class Lzip
     include UnpackStrategy
 
-    def self.can_extract?(path:, magic_number:)
-      magic_number.match?(/\ALZIP/n)
+    using Magic
+
+    def self.can_extract?(path)
+      path.magic_number.match?(/\ALZIP/n)
     end
 
     def dependencies

Library/Homebrew/unpack_strategy/lzma.rb

@@ -2,8 +2,10 @@ module UnpackStrategy
   class Lzma
     include UnpackStrategy
 
-    def self.can_extract?(path:, magic_number:)
-      magic_number.match?(/\A\]\000\000\200\000/n)
+    using Magic
+
+    def self.can_extract?(path)
+      path.magic_number.match?(/\A\]\000\000\200\000/n)
     end
 
     def extract_to_dir(unpack_dir, basename:, verbose:)

Library/Homebrew/unpack_strategy/mercurial.rb

@@ -2,7 +2,9 @@ require_relative "directory"
 
 module UnpackStrategy
   class Mercurial < Directory
-    def self.can_extract?(path:, magic_number:)
+    using Magic
+
+    def self.can_extract?(path)
       super && (path/".hg").directory?
     end
 

Library/Homebrew/unpack_strategy/microsoft_office_xml.rb

@@ -2,12 +2,14 @@ require_relative "uncompressed"
 
 module UnpackStrategy
   class MicrosoftOfficeXml < Uncompressed
-    def self.can_extract?(path:, magic_number:)
-      return false unless Zip.can_extract?(path: path, magic_number: magic_number)
+    using Magic
+
+    def self.can_extract?(path)
+      return false unless Zip.can_extract?(path)
 
       # Check further if the ZIP is a Microsoft Office XML document.
-      magic_number.match?(/\APK\003\004/n) &&
-        magic_number.match?(%r{\A.{30}(\[Content_Types\]\.xml|_rels/\.rels)}n)
+      path.magic_number.match?(/\APK\003\004/n) &&
+        path.magic_number.match?(%r{\A.{30}(\[Content_Types\]\.xml|_rels/\.rels)}n)
     end
   end
 end

Library/Homebrew/unpack_strategy/otf.rb

@@ -2,8 +2,10 @@ require_relative "uncompressed"
 
 module UnpackStrategy
   class Otf < Uncompressed
-    def self.can_extract?(path:, magic_number:)
-      magic_number.match?(/\AOTTO/n)
+    using Magic
+
+    def self.can_extract?(path)
+      path.magic_number.match?(/\AOTTO/n)
     end
   end
 end

Library/Homebrew/unpack_strategy/p7zip.rb

@@ -2,8 +2,10 @@ module UnpackStrategy
   class P7Zip
     include UnpackStrategy
 
-    def self.can_extract?(path:, magic_number:)
-      magic_number.match?(/\A7z\xBC\xAF\x27\x1C/n)
+    using Magic
+
+    def self.can_extract?(path)
+      path.magic_number.match?(/\A7z\xBC\xAF\x27\x1C/n)
     end
 
     def dependencies

Library/Homebrew/unpack_strategy/pkg.rb

@@ -2,9 +2,11 @@ require_relative "uncompressed"
 
 module UnpackStrategy
   class Pkg < Uncompressed
-    def self.can_extract?(path:, magic_number:)
+    using Magic
+
+    def self.can_extract?(path)
       path.extname.match?(/\A.m?pkg\Z/) &&
-        (path.directory? || magic_number.match?(/\Axar!/n))
+        (path.directory? || path.magic_number.match?(/\Axar!/n))
     end
   end
 end

Library/Homebrew/unpack_strategy/rar.rb

@@ -2,8 +2,10 @@ module UnpackStrategy
   class Rar
     include UnpackStrategy
 
-    def self.can_extract?(path:, magic_number:)
-      magic_number.match?(/\ARar!/n)
+    using Magic
+
+    def self.can_extract?(path)
+      path.magic_number.match?(/\ARar!/n)
     end
 
     def dependencies

Library/Homebrew/unpack_strategy/self_extracting_executable.rb

@@ -2,12 +2,12 @@ require_relative "generic_unar"
 
 module UnpackStrategy
   class SelfExtractingExecutable < GenericUnar
-    def self.can_extract?(path:, magic_number:)
-      return false unless magic_number.match?(/\AMZ/n)
+    using Magic
 
-      system_command("file",
-                     args: [path],
-                     print_stderr: false).stdout.include?("self-extracting")
+    def self.can_extract?(path)
+      return false unless path.magic_number.match?(/\AMZ/n)
+
+      path.file_type.include?("self-extracting archive")
     end
   end
 end

Library/Homebrew/unpack_strategy/sit.rb

@@ -2,8 +2,10 @@ require_relative "generic_unar"
 
 module UnpackStrategy
   class Sit < GenericUnar
-    def self.can_extract?(path:, magic_number:)
-      magic_number.match?(/\AStuffIt/n)
+    using Magic
+
+    def self.can_extract?(path)
+      path.magic_number.match?(/\AStuffIt/n)
     end
   end
 end

Library/Homebrew/unpack_strategy/subversion.rb

@@ -2,7 +2,9 @@ require_relative "directory"
 
 module UnpackStrategy
   class Subversion < Directory
-    def self.can_extract?(path:, magic_number:)
+    using Magic
+
+    def self.can_extract?(path)
       super && (path/".svn").directory?
     end
 

Library/Homebrew/unpack_strategy/tar.rb

@@ -2,8 +2,14 @@ module UnpackStrategy
   class Tar
     include UnpackStrategy
 
-    def self.can_extract?(path:, magic_number:)
-      return true if magic_number.match?(/\A.{257}ustar/n)
+    using Magic
+
+    def self.can_extract?(path)
+      return true if path.magic_number.match?(/\A.{257}ustar/n)
+
+      unless [Bzip2, Gzip, Lzip, Xz].any? { |s| s.can_extract?(path) }
+        return false
+      end
 
       # Check if `tar` can list the contents, then it can also extract it.
       IO.popen(["tar", "tf", path], err: File::NULL) do |stdout|

Library/Homebrew/unpack_strategy/ttf.rb

@@ -2,11 +2,13 @@ require_relative "uncompressed"
 
 module UnpackStrategy
   class Ttf < Uncompressed
-    def self.can_extract?(path:, magic_number:)
+    using Magic
+
+    def self.can_extract?(path)
       # TrueType Font
-      magic_number.match?(/\A\000\001\000\000\000/n) ||
+      path.magic_number.match?(/\A\000\001\000\000\000/n) ||
         # Truetype Font Collection
-        magic_number.match?(/\Attcf/n)
+        path.magic_number.match?(/\Attcf/n)
     end
   end
 end

Library/Homebrew/unpack_strategy/xar.rb

@@ -2,8 +2,10 @@ module UnpackStrategy
   class Xar
     include UnpackStrategy
 
-    def self.can_extract?(path:, magic_number:)
-      magic_number.match?(/\Axar!/n)
+    using Magic
+
+    def self.can_extract?(path)
+      path.magic_number.match?(/\Axar!/n)
     end
 
     private

Library/Homebrew/unpack_strategy/xz.rb

@@ -2,8 +2,10 @@ module UnpackStrategy
   class Xz
     include UnpackStrategy
 
-    def self.can_extract?(path:, magic_number:)
-      magic_number.match?(/\A\xFD7zXZ\x00/n)
+    using Magic
+
+    def self.can_extract?(path)
+      path.magic_number.match?(/\A\xFD7zXZ\x00/n)
     end
 
     def dependencies

Library/Homebrew/unpack_strategy/zip.rb

@@ -2,8 +2,10 @@ module UnpackStrategy
   class Zip
     include UnpackStrategy
 
-    def self.can_extract?(path:, magic_number:)
-      magic_number.match?(/\APK(\003\004|\005\006)/n)
+    using Magic
+
+    def self.can_extract?(path)
+      path.magic_number.match?(/\APK(\003\004|\005\006)/n)
     end
 
     private