Merge pull request #3437 from CocoaPods/seg-popen3

[Executable] Use popen3 instead of open4 to execute commands

CHANGELOG.md

@@ -17,6 +17,12 @@ To install release candidates run `[sudo] gem install cocoapods --pre`
   [Mason Glidden](https://github.com/mglidden)
   [#1154](https://github.com/CocoaPods/CocoaPods/issues/1154)
 
+* Handle subprocesses leaking STDOUT/STDERR pipes by more strictly managing
+  process lifetime and not allowing I/O to block completion of the task.  
+  [Samuel Giddins](https://github.com/segiddins)
+  [#3101](https://github.com/CocoaPods/CocoaPods/issues/3101)
+
+
 ## 0.37.0.beta.1
 
 ##### Enhancements

Gemfile.lock

@@ -77,7 +77,6 @@ PATH
       escape (~> 0.0.4)
       molinillo (~> 0.2.3)
       nap (~> 0.8)
-      open4 (~> 1.3)
       xcodeproj (~> 0.24.0)
 
 GEM
@@ -124,7 +123,6 @@ GEM
     nap (0.8.0)
     netrc (0.7.8)
     notify (0.5.2)
-    open4 (1.3.4)
     parser (2.2.0.3)
       ast (>= 1.1, < 3.0)
     powerpack (0.1.0)

cocoapods.gemspec

@@ -38,7 +38,6 @@ Gem::Specification.new do |s|
 
   s.add_runtime_dependency 'colored',       '~> 1.2'
   s.add_runtime_dependency 'escape',        '~> 0.0.4'
-  s.add_runtime_dependency 'open4',         '~> 1.3'
   s.add_runtime_dependency 'activesupport', '>= 3.2.15'
   s.add_runtime_dependency 'nap',           '~> 0.8'
 

lib/cocoapods/executable.rb

@@ -51,7 +51,6 @@ module Pod
       bin = `which #{executable}`.strip
       raise Informative, "Unable to locate the executable `#{executable}`" if bin.empty?
 
-      require 'open4'
       require 'shellwords'
 
       command = command.map(&:to_s)
@@ -64,8 +63,7 @@ module Pod
         stdout, stderr = Indenter.new, Indenter.new
       end
 
-      options = { :stdout => stdout, :stderr => stderr, :status => true }
-      status  = Open4.spawn(bin, command, options)
+      status = popen3(bin, command, stdout, stderr)
       output = stdout.join("\n") + stderr.join("\n")
       unless status.success?
         if raise_on_failure
@@ -77,6 +75,27 @@ module Pod
       output
     end
 
+    private
+
+    def self.popen3(bin, command, stdout, stderr)
+      require 'open3'
+      Open3.popen3(bin, *command) do |i, o, e, t|
+        out_reader = Thread.new { while s = o.gets; stdout << s; end }
+        err_reader = Thread.new { while s = e.gets; stderr << s; end }
+
+        i.close
+
+        run_readers = lambda do
+          [out_reader, err_reader].each do |reader|
+            reader.run if reader.alive?
+          end
+        end
+
+        run_readers.call
+        t.value.tap { run_readers.call }
+      end
+    end
+
     #-------------------------------------------------------------------------#
 
     # Helper class that allows to write to an {IO} instance taking into account

spec/unit/executable_spec.rb

@@ -16,8 +16,18 @@ module Pod
       result = mock
       result.stubs(:success?).returns(true)
 
-      Open4.expects(:spawn).with('/Spa ces/are"/fun/false', [], :stdout => [], :stderr => [], :status => true).once.returns(result)
+      Open3.expects(:popen3).with('/Spa ces/are"/fun/false').once.returns(result)
       Executable.execute_command(cmd, [], true)
     end
+
+    it "doesn't hang when the spawned process forks a zombie process with the same STDOUT and STDERR" do
+      cmd = ['-e', <<-RB]
+        Process.fork { Process.daemon(nil, true); sleep(2) }
+        puts 'out'
+      RB
+      Timeout.timeout(1) do
+        Executable.execute_command('ruby', cmd, true).should == "out\n"
+      end
+    end
   end
 end