radare2: Added signing option

Added the option to sign the build, it uses the built in commands from
the radare2 Makefile. In order for it to succeed the org.radare.radare2
certificate must exist in the keychain. The process is defined in
https://github.com/radare/radare2/blob/master/doc/osx.md

Closes #3838.

Signed-off-by: Andrew Janke <janke@eilonwy.local>

Formula/radare2.rb

@@ -1,3 +1,22 @@
+class CodesignRequirement < Requirement
+  include FileUtils
+  fatal true
+
+  satisfy(:build_env => false) do
+    mktemp do
+      cp "/usr/bin/false", "radare2_check"
+      quiet_system "/usr/bin/codesign", "-f", "-s", "org.radare.radare2", "--dryrun", "radare2_check"
+    end
+  end
+
+  def message
+    <<-EOS.undent
+      org.radare.radare2 identity must be available to build with automated signing.
+      See: https://github.com/radare/radare2/blob/master/doc/osx.md
+    EOS
+  end
+end
+
 class Radare2 < Formula
   desc "Reverse engineering framework"
   homepage "http://radare.org"
@@ -35,6 +54,8 @@ class Radare2 < Formula
     end
   end
 
+  option "with-code-signing", "Codesign executables to provide unprivileged process attachment"
+
   depends_on "pkg-config" => :build
   depends_on "valabind" => :build
   depends_on "swig" => :build
@@ -46,10 +67,18 @@ class Radare2 < Formula
   depends_on "openssl"
   depends_on "yara"
 
+  depends_on CodesignRequirement if build.with? "code-signing"
+
   def install
     # Build Radare2 before bindings, otherwise compile = nope.
     system "./configure", "--prefix=#{prefix}", "--with-openssl"
     system "make", "CS_PATCHES=0"
+    if build.with? "code-signing"
+      # Brew changes the HOME directory which breaks codesign
+      home = `eval printf "~$USER"`
+      system "make", "HOME=#{home}", "-C", "binr/radare2", "osxsign"
+      system "make", "HOME=#{home}", "-C", "binr/radare2", "osx-sign-libs"
+    end
     system "make", "install"
 
     resource("extras").stage do