os/mac: optionally use ruby_macho.

- and branch for dylib_id_and_dylibs
- add branches for dylib id changing and change_install_name
- rename MachO module to HomebrewMachO to prevent namespace clashes
  with MachO in ruby-macho. this will eventually be replaced entirely
  with direct calls to ruby-macho methods
- break ruby-macho implementation out into separate RubyMachO module,
  and include either RubyMachO or CctoolsMachO (the original
  implementation) based on the HOMEBREW_RUBY_MACHO env var
- move ArchitectureListExtension and RubyMachO into separate files
- create {ruby_,cctools_,,}relocate.rb for isolation of different
  methods of mach-o relocation (ruby-macho vs. cctools)
- fill in require_install_name_tool? for ruby_relocate.rb
- rename {ruby_,cctools_,,}relocate.rb to keg, isolate requires in
  os/mac

Closes Homebrew/homebrew#45001.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Library/Homebrew/keg_relocate.rb

@@ -70,16 +70,6 @@ class Keg
     end
   end
 
-  def change_dylib_id(id, file)
-    puts "Changing dylib ID of #{file}\n  from #{file.dylib_id}\n    to #{id}" if ARGV.debug?
-    install_name_tool("-id", id, file)
-  end
-
-  def change_install_name(old, new, file)
-    puts "Changing install name in #{file}\n  from #{old}\n    to #{new}" if ARGV.debug?
-    install_name_tool("-change", old, new, file)
-  end
-
   # Detects the C++ dynamic libraries in place, scanning the dynamic links
   # of the files within the keg.
   # Note that this doesn't attempt to distinguish between libstdc++ versions,
@@ -110,16 +100,6 @@ class Keg
     end
   end
 
-  def install_name_tool(*args)
-    @require_install_name_tool = true
-    tool = MacOS.install_name_tool
-    system(tool, *args) || raise(ErrorDuringExecution.new(tool, args))
-  end
-
-  def require_install_name_tool?
-    !!@require_install_name_tool
-  end
-
   # If file is a dylib or bundle itself, look for the dylib named by
   # bad_name relative to the lib directory, so that we can skip the more
   # expensive recursive search if possible.

Library/Homebrew/os/mac.rb

@@ -4,6 +4,7 @@ require "os/mac/xcode"
 require "os/mac/xquartz"
 require "os/mac/pathname"
 require "os/mac/sdk"
+require "os/mac/keg"
 
 module OS
   module Mac

Library/Homebrew/os/mac/cctools_keg.rb

@@ -0,0 +1,21 @@
+module CctoolsKeg
+  def install_name_tool(*args)
+    @require_install_name_tool = true
+    tool = MacOS.install_name_tool
+    system(tool, *args) || raise(ErrorDuringExecution.new(tool, args))
+  end
+
+  def require_install_name_tool?
+    !!@require_install_name_tool
+  end
+
+  def change_dylib_id(id, file)
+    puts "Changing dylib ID of #{file}\n  from #{file.dylib_id}\n    to #{id}" if ARGV.debug?
+    install_name_tool("-id", id, file)
+  end
+
+  def change_install_name(old, new, file)
+    puts "Changing install name in #{file}\n  from #{old}\n    to #{new}" if ARGV.debug?
+    install_name_tool("-change", old, new, file)
+  end
+end

Library/Homebrew/os/mac/hardware.rb

@@ -1,4 +1,4 @@
-require "os/mac/mach"
+require "os/mac/pathname"
 
 module MacCPUs
   OPTIMIZATION_FLAGS = {

Library/Homebrew/os/mac/keg.rb

@@ -0,0 +1,9 @@
+class Keg
+  if ENV["HOMEBREW_RUBY_MACHO"]
+    require "os/mac/ruby_keg"
+    include RubyKeg
+  else
+    require "os/mac/cctools_keg"
+    include CctoolsKeg
+  end
+end

Library/Homebrew/os/mac/pathname.rb

@@ -1,5 +1,9 @@
-require "os/mac/mach"
-
 class Pathname
-  include MachO
+  if ENV["HOMEBREW_RUBY_MACHO"]
+    require "os/mac/ruby_mach"
+    include RubyMachO
+  else
+    require "os/mac/cctools_mach"
+    include CctoolsMachO
+  end
 end

Library/Homebrew/os/mac/ruby_keg.rb

@@ -0,0 +1,19 @@
+require "vendor/macho/macho"
+
+module RubyKeg
+  def change_dylib_id(id, file)
+    @require_install_name_tool = true
+    puts "Changing dylib ID of #{file}\n  from #{file.dylib_id}\n    to #{id}" if ARGV.debug?
+    MachO::Tools.change_dylib_id(file, id)
+  end
+
+  def change_install_name(old, new, file)
+    @require_install_name_tool = true
+    puts "Changing install name in #{file}\n  from #{old}\n    to #{new}" if ARGV.debug?
+    MachO::Tools.change_install_name(file, old, new)
+  end
+
+  def require_install_name_tool?
+    !!@require_install_name_tool
+  end
+end

Library/Homebrew/os/mac/ruby_mach.rb

@@ -0,0 +1,103 @@
+require "vendor/macho/macho"
+require "os/mac/architecture_list"
+
+module RubyMachO
+  # @private
+  def macho
+    @macho ||= begin
+      MachO.open(to_s)
+    end
+  end
+
+  # @private
+  def mach_data
+    @mach_data ||= begin
+      machos = []
+      mach_data = []
+
+      if MachO.fat_magic?(macho.magic)
+        machos = macho.machos
+      else
+        machos << macho
+      end
+
+      machos.each do |m|
+        arch = case m.cputype
+        when "CPU_TYPE_I386" then :i386
+        when "CPU_TYPE_X86_64" then :x86_64
+        when "CPU_TYPE_POWERPC" then :ppc7400
+        when "CPU_TYPE_POWERPC64" then :ppc64
+        else :dunno
+        end
+
+        type = case m.filetype
+        when "MH_EXECUTE" then :executable
+        when "MH_DYLIB" then :dylib
+        when "MH_BUNDLE" then :bundle
+        else :dunno
+        end
+
+        mach_data << { :arch => arch, :type => type }
+      end
+
+      mach_data
+    rescue
+      []
+    end
+  end
+
+  def archs
+    mach_data.map { |m| m.fetch :arch }.extend(ArchitectureListExtension)
+  end
+
+  def arch
+    case archs.length
+    when 0 then :dunno
+    when 1 then archs.first
+    else :universal
+    end
+  end
+
+  def universal?
+    arch == :universal
+  end
+
+  def i386?
+    arch == :i386
+  end
+
+  def x86_64?
+    arch == :x86_64
+  end
+
+  def ppc7400?
+    arch == :ppc7400
+  end
+
+  def ppc64?
+    arch == :ppc64
+  end
+
+  # @private
+  def dylib?
+    mach_data.any? { |m| m.fetch(:type) == :dylib }
+  end
+
+  # @private
+  def mach_o_executable?
+    mach_data.any? { |m| m.fetch(:type) == :executable }
+  end
+
+  # @private
+  def mach_o_bundle?
+    mach_data.any? { |m| m.fetch(:type) == :bundle }
+  end
+
+  def dynamically_linked_libraries
+    macho.linked_dylibs
+  end
+
+  def dylib_id
+    macho.dylib_id
+  end
+end