From bf0e488c06bd61ceded37ae04babbdc5f8aa600d Mon Sep 17 00:00:00 2001
From: Brandon Keepers <brandon@opensoul.org>
Date: Wed, 10 Dec 2014 10:58:14 -0500
Subject: [PATCH 1/5] Test case for case causing error

---
 test/test_shebang.rb | 1 +
 1 file changed, 1 insertion(+)

diff --git a/test/test_shebang.rb b/test/test_shebang.rb
index 4b6b39a6..071a436c 100644
--- a/test/test_shebang.rb
+++ b/test/test_shebang.rb
@@ -17,6 +17,7 @@ class TestShebang < Test::Unit::TestCase
     assert_interpreter nil, " #!/usr/sbin/ruby"
     assert_interpreter nil, "\n#!/usr/sbin/ruby"
     assert_interpreter nil, "#!"
+    assert_interpreter nil, "#! "
 
     assert_interpreter "ruby", "#!/usr/sbin/ruby\n# bar"
     assert_interpreter "ruby", "#!/usr/bin/ruby\n# foo"

From afac6a918d84a8c8e14165bf6ea0ca1edd7a482c Mon Sep 17 00:00:00 2001
From: Brandon Keepers <brandon@opensoul.org>
Date: Wed, 10 Dec 2014 11:00:32 -0500
Subject: [PATCH 2/5] Handle empty shebang with whitespace

---
 lib/linguist/shebang.rb | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/lib/linguist/shebang.rb b/lib/linguist/shebang.rb
index 3405bb62..07694667 100644
--- a/lib/linguist/shebang.rb
+++ b/lib/linguist/shebang.rb
@@ -19,11 +19,12 @@ module Linguist
     # Returns a String or nil
     def self.interpreter(data)
       lines = data.lines
-      return unless match = /^#! ?(.+)$/.match(lines.first)
 
-      tokens = match[1].split(' ')
-      script = tokens.first.split('/').last
+      return unless match = /^#!(.+)$/.match(lines.first)
 
+      tokens = match[1].strip.split(' ')
+      return if tokens.empty?
+      script = File.basename(tokens.first)
       script = tokens[1] if script == 'env'
 
       # If script has an invalid shebang, we might get here

From 1490425ecbbf02cb5daf3d4f281511635f4f22c0 Mon Sep 17 00:00:00 2001
From: Brandon Keepers <brandon@opensoul.org>
Date: Wed, 10 Dec 2014 11:00:41 -0500
Subject: [PATCH 3/5] document shebang code

---
 lib/linguist/shebang.rb | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/lib/linguist/shebang.rb b/lib/linguist/shebang.rb
index 07694667..4e47ad6b 100644
--- a/lib/linguist/shebang.rb
+++ b/lib/linguist/shebang.rb
@@ -20,18 +20,25 @@ module Linguist
     def self.interpreter(data)
       lines = data.lines
 
+      # First line must start with #!
       return unless match = /^#!(.+)$/.match(lines.first)
 
       tokens = match[1].strip.split(' ')
+
+      # There was nothing after the #!
       return if tokens.empty?
+
+      # Get the name of the interpreter
       script = File.basename(tokens.first)
+
+      # Get next argument if interpreter was /usr/bin/env
       script = tokens[1] if script == 'env'
 
-      # If script has an invalid shebang, we might get here
+      # Interpreter was /usr/bin/env with no arguments
       return unless script
 
       # "python2.6" -> "python2"
-      script.sub! $1, '' if script =~ /(\.\d+)$/
+      script.sub! /(\.\d+)$/, ''
 
       # Check for multiline shebang hacks that call `exec`
       if script == 'sh' &&

From 6efee511011b5a592a5221927e7050aa345e5dd7 Mon Sep 17 00:00:00 2001
From: Brandon Keepers <brandon@opensoul.org>
Date: Wed, 10 Dec 2014 11:00:46 -0500
Subject: [PATCH 4/5] Add missing test cases

---
 test/test_shebang.rb | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/test/test_shebang.rb b/test/test_shebang.rb
index 071a436c..5ead299d 100644
--- a/test/test_shebang.rb
+++ b/test/test_shebang.rb
@@ -18,6 +18,7 @@ class TestShebang < Test::Unit::TestCase
     assert_interpreter nil, "\n#!/usr/sbin/ruby"
     assert_interpreter nil, "#!"
     assert_interpreter nil, "#! "
+    assert_interpreter nil, "#!/usr/bin/env"
 
     assert_interpreter "ruby", "#!/usr/sbin/ruby\n# bar"
     assert_interpreter "ruby", "#!/usr/bin/ruby\n# foo"
@@ -35,6 +36,8 @@ class TestShebang < Test::Unit::TestCase
     assert_interpreter "python3", "#!/usr/bin/python3\n\n\n\n"
     assert_interpreter "sbcl", "#!/usr/bin/sbcl --script\n\n"
     assert_interpreter "perl", "#! perl"
+
+    assert_interpreter "ruby", "#!/bin/sh\n\n\nexec ruby $0 $@"
   end
 
 end

From 21b8e16afc15e84dce7161822aba173eba52750c Mon Sep 17 00:00:00 2001
From: Brandon Keepers <brandon@opensoul.org>
Date: Wed, 10 Dec 2014 12:05:37 -0500
Subject: [PATCH 5/5] Use #start_with? for clarity

---
 lib/linguist/shebang.rb | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/lib/linguist/shebang.rb b/lib/linguist/shebang.rb
index 4e47ad6b..6f04e866 100644
--- a/lib/linguist/shebang.rb
+++ b/lib/linguist/shebang.rb
@@ -18,12 +18,13 @@ module Linguist
     #
     # Returns a String or nil
     def self.interpreter(data)
-      lines = data.lines
+      shebang = data.lines.first
 
       # First line must start with #!
-      return unless match = /^#!(.+)$/.match(lines.first)
+      return unless shebang && shebang.start_with?("#!")
 
-      tokens = match[1].strip.split(' ')
+      # Get the parts of the shebang without the #!
+      tokens = shebang.sub(/^#!\s*/, '').strip.split(' ')
 
       # There was nothing after the #!
       return if tokens.empty?
@@ -42,7 +43,7 @@ module Linguist
 
       # Check for multiline shebang hacks that call `exec`
       if script == 'sh' &&
-        lines.first(5).any? { |l| l.match(/exec (\w+).+\$0.+\$@/) }
+        data.lines.first(5).any? { |l| l.match(/exec (\w+).+\$0.+\$@/) }
         script = $1
       end