Merge pull request #7778 from justjake/subprocess-closable-stdin

Allow closing a Vagrant::Util::Subprocess's STDIN

lib/vagrant/util/subprocess.rb

@@ -144,10 +144,11 @@ module Vagrant
         # Record the start time for timeout purposes
         start_time = Time.now.to_i
 
+        open_readers = [stdout, stderr]
+        open_writers = notify_stdin ? [process.io.stdin] : []
         @logger.debug("Selecting on IO")
         while true
-          writers = notify_stdin ? [process.io.stdin] : []
+          results = ::IO.select(open_readers, open_writers, nil, 0.1)
-          results = ::IO.select([stdout, stderr], writers, nil, 0.1)
           results ||= []
           readers = results[0]
           writers = results[1]
@@ -178,8 +179,14 @@ module Vagrant
           break if process.exited?
 
           # Check the writers to see if they're ready, and notify any listeners
-          if writers && !writers.empty?
+          if writers && !writers.empty? && block_given?
-            yield :stdin, process.io.stdin if block_given?
+            yield :stdin, process.io.stdin
+
+            # if the callback closed stdin, we should remove it, because
+            # IO.select() will throw if called with a closed io.
+            if process.io.stdin.closed?
+              open_writers = []
+            end
           end
         end
 

test/unit/vagrant/util/subprocess_test.rb

@@ -0,0 +1,50 @@
+require File.expand_path("../../../base", __FILE__)
+require "vagrant/util/subprocess"
+
+describe Vagrant::Util::Subprocess do
+  describe '#execute' do
+    before do
+      # ensure we have `cat` and `echo` in our PATH so that we can run these
+      # tests successfully.
+      ['cat', 'echo'].each do |cmd|
+        if !Vagrant::Util::Which.which(cmd)
+          pending("cannot run subprocess tests without command #{cmd.inspect}")
+        end
+      end
+    end
+
+    let (:cat) { described_class.new('cat', :notify => [:stdin]) }
+
+    it 'yields the STDIN stream for the process if we set :notify => :stdin' do
+      echo = described_class.new('echo', 'hello world', :notify => [:stdin])
+      echo.execute do |type, data|
+        expect(type).to eq(:stdin)
+        expect(data).to be_a(::IO)
+      end
+    end
+
+    it 'can close STDIN' do
+      result = cat.execute do |type, stdin|
+        # We should be able to close STDIN without raising an exception
+        stdin.close
+      end
+
+      # we should exit successfully.
+      expect(result.exit_code).to eq(0)
+    end
+
+    it 'can write to STDIN correctly' do
+      data = "hello world\n"
+      result = cat.execute do |type, stdin|
+        stdin.write(data)
+        stdin.close
+      end
+
+      # we should exit successfully.
+      expect(result.exit_code).to eq(0)
+
+      # we should see our data as the output from `cat`
+      expect(result.stdout).to eq(data)
+    end
+  end
+end