Fix issue related to command output filling up the IO pipe.

lib/linux_admin/common.rb

@@ -2,20 +2,57 @@ module LinuxAdmin
   module Common
     def self.run(cmd, options = {})
       begin
-        r, w = IO.pipe
-        pid, status = Process.wait2(Kernel.spawn(cmd, :err => [:child, :out], :out => w))
-        w.close
-        if options[:return_output] && status.exitstatus == 0
-          r.read
-        elsif options[:return_exitstatus] || status.exitstatus == 0
-          status.exitstatus
+        out = launch(cmd)
+        if options[:return_output] && exitstatus == 0
+          out
+        elsif options[:return_exitstatus] || exitstatus == 0
+          exitstatus
         else
-          raise "Error: Exit Code #{status.exitstatus}"
+          raise "Error: Exit Code #{exitstatus}"
         end
       rescue
         return nil if options[:return_exitstatus]
         raise
+      ensure
+        self.exitstatus = nil
       end
     end
+
+    private
+
+    # IO pipes have a maximum size of 64k before blocking,
+    # so we need to read and write synchronously.
+    # http://stackoverflow.com/questions/13829830/ruby-process-spawn-stdout-pipe-buffer-size-limit/13846146#13846146
+    THREAD_SYNC_KEY = "LinuxAdmin-exitstatus"
+
+    def self.launch(cmd)
+      pipe_r, pipe_w = IO.pipe
+      pid = Kernel.spawn(cmd, :err => [:child, :out], :out => pipe_w)
+      wait_for_process(pid, pipe_w)
+      wait_for_output(pipe_r)
+    end
+
+    def self.wait_for_process(pid, pipe_w)
+      self.exitstatus = :not_done
+      Thread.new(Thread.current) do |parent_thread|
+        _, status = Process.wait2(pid)
+        pipe_w.close
+        parent_thread[THREAD_SYNC_KEY] = status.exitstatus
+      end
+    end
+
+    def self.wait_for_output(pipe_r)
+      out = pipe_r.read
+      sleep(0.1) while exitstatus == :not_done
+      return out
+    end
+
+    def self.exitstatus
+      Thread.current[THREAD_SYNC_KEY]
+    end
+
+    def self.exitstatus=(value)
+      Thread.current[THREAD_SYNC_KEY] = value
+    end
   end
 end