From ab814e4dd3cf06559a95ca5dd19722431314f6fa Mon Sep 17 00:00:00 2001
From: Michael Kozono <mkozono@gmail.com>
Date: Wed, 8 Nov 2017 12:53:10 -0800
Subject: [PATCH] Backport `which` from EE

---
 lib/gitlab/utils.rb           | 17 +++++++++++++++++
 spec/lib/gitlab/utils_spec.rb | 10 +++++++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/lib/gitlab/utils.rb b/lib/gitlab/utils.rb
index abb3d3a02c3..b3baaf036d8 100644
--- a/lib/gitlab/utils.rb
+++ b/lib/gitlab/utils.rb
@@ -46,5 +46,22 @@ module Gitlab
     def random_string
       Random.rand(Float::MAX.to_i).to_s(36)
     end
+
+    # See: http://stackoverflow.com/questions/2108727/which-in-ruby-checking-if-program-exists-in-path-from-ruby
+    # Cross-platform way of finding an executable in the $PATH.
+    #
+    #   which('ruby') #=> /usr/bin/ruby
+    def which(cmd, env = ENV)
+      exts = env['PATHEXT'] ? env['PATHEXT'].split(';') : ['']
+
+      env['PATH'].split(File::PATH_SEPARATOR).each do |path|
+        exts.each do |ext|
+          exe = File.join(path, "#{cmd}#{ext}")
+          return exe if File.executable?(exe) && !File.directory?(exe)
+        end
+      end
+
+      nil
+    end
   end
 end
diff --git a/spec/lib/gitlab/utils_spec.rb b/spec/lib/gitlab/utils_spec.rb
index 3137a72fdc4..e872a5290c5 100644
--- a/spec/lib/gitlab/utils_spec.rb
+++ b/spec/lib/gitlab/utils_spec.rb
@@ -1,7 +1,7 @@
 require 'spec_helper'
 
 describe Gitlab::Utils do
-  delegate :to_boolean, :boolean_to_yes_no, :slugify, :random_string, to: :described_class
+  delegate :to_boolean, :boolean_to_yes_no, :slugify, :random_string, :which, to: :described_class
 
   describe '.slugify' do
     {
@@ -59,4 +59,12 @@ describe Gitlab::Utils do
       expect(random_string).to be_kind_of(String)
     end
   end
+
+  describe '.which' do
+    it 'finds the full path to an executable binary' do
+      expect(File).to receive(:executable?).with('/bin/sh').and_return(true)
+
+      expect(which('sh', 'PATH' => '/bin')).to eq('/bin/sh')
+    end
+  end
 end