Add popen wrapper that does not invoke the shell

Library/Homebrew/test/test_utils.rb

@@ -5,4 +5,10 @@ class UtilTests < Homebrew::TestCase
     # Issue #217 put columns with new results fails.
     assert_silent { puts_columns [] }
   end
+
+  def test_popen_read
+    out = Utils.popen_read("/bin/sh", "-c", "echo success", &:read).chomp
+    assert_equal "success", out
+    assert_predicate $?, :success?
+  end
 end

Library/Homebrew/utils.rb

@@ -3,6 +3,7 @@ require 'exceptions'
 require 'os/mac'
 require 'utils/json'
 require 'utils/inreplace'
+require 'utils/popen'
 require 'open-uri'
 
 class Tty

Library/Homebrew/utils/popen.rb

@@ -0,0 +1,20 @@
+module Utils
+  def self.popen_read(*args, &block)
+    popen(args, "rb", &block)
+  end
+
+  def self.popen_write(*args, &block)
+    popen(args, "wb", &block)
+  end
+
+  def self.popen(args, mode)
+    IO.popen("-", mode) do |pipe|
+      if pipe
+        yield pipe
+      else
+        STDERR.reopen("/dev/null", "w")
+        exec(*args)
+      end
+    end
+  end
+end