Fix for #2731 (problem communicating with processes in SELinux)

In some cases communicating with child processes via temprary files is not
viable.  This is Ricky Zhou's patch from the ticket, which solves the problem
by using the more normal system of pipes.  It is a broader reaching change
than suggested by the ticket (it affects all execs, not just SELinux) but IMHO
is the right way to go.

Signed-off-by: Markus Roberts <Markus@reality.com>

1 files changed, 22 insertions, 51 deletions

diff --git a/lib/puppet/util.rb b/lib/puppet/util.rb
index 21573d1da..dd6ae69fa 100644
--- a/lib/puppet/util.rb
+++ b/lib/puppet/util.rb
@@ -259,28 +259,17 @@ module Util
         @@os ||= Facter.value(:operatingsystem)
         output = nil
         child_pid, child_status = nil
-        # There are problems with read blocking with badly behaved children
-        # read.partialread doesn't seem to capture either stdout or stderr
-        # We hack around this using a temporary file
-
-        # The idea here is to avoid IO#read whenever possible.
-        output_file="/dev/null"
-        error_file="/dev/null"
-        if ! arguments[:squelch]
-            require "tempfile"
-            output_file = Tempfile.new("puppet")
-            if arguments[:combine]
-                error_file=output_file
-            end
-        end
+        output_read, output_write = IO.pipe
 
         oldverb = $VERBOSE
         $VERBOSE = nil
         child_pid = Kernel.fork
         $VERBOSE = oldverb
         if child_pid
+            output_write.close
             # Parent process executes this
-            child_status = (Process.waitpid2(child_pid)[1]).to_i >> 8
+            Process.waitpid(child_pid)
+            child_status = $?.exitstatus
         else
             # Child process executes this
             Process.setsid
@@ -288,10 +277,18 @@ module Util
                 if arguments[:stdinfile]
                     $stdin.reopen(arguments[:stdinfile])
                 else
-                    $stdin.reopen("/dev/null")
+                    $stdin.close
+                end
+                if arguments[:squelch]
+                    $stdout.close
+                else
+                    $stdout.reopen(output_write)
+                end
+                if arguments[:combine]
+                    $stderr.reopen(output_write)
+                else
+                    $stderr.close
                 end
-                $stdout.reopen(output_file)
-                $stderr.reopen(error_file)
 
                 3.upto(256){|fd| IO::new(fd).close rescue nil}
                 if arguments[:gid]
@@ -303,43 +300,17 @@ module Util
                     Process.uid = arguments[:uid] unless @@os == "Darwin"
                 end
                 ENV['LANG'] = ENV['LC_ALL'] = ENV['LC_MESSAGES'] = ENV['LANGUAGE'] = 'C'
-                if command.is_a?(Array)
-                    Kernel.exec(*command)
-                else
-                    Kernel.exec(command)
-                end
+                Kernel.exec(*command)
             rescue => detail
-                puts detail.to_s
+                puts detail
                 exit!(1)
-            end # begin; rescue
-        end # if child_pid
+            end
+        end
 
         # read output in if required
         if ! arguments[:squelch]
-
-            # Make sure the file's actually there.  This is
-            # basically a race condition, and is probably a horrible
-            # way to handle it, but, well, oh well.
-            unless FileTest.exists?(output_file.path)
-                Puppet.warning "sleeping"
-                sleep 0.5
-                unless FileTest.exists?(output_file.path)
-                    Puppet.warning "sleeping 2"
-                    sleep 1
-                    unless FileTest.exists?(output_file.path)
-                        Puppet.warning "Could not get output"
-                        output = ""
-                    end
-                end
-            end
-            unless output
-                # We have to explicitly open here, so that it reopens
-                # after the child writes.
-                output = output_file.open.read
-
-                # The 'true' causes the file to get unlinked right away.
-                output_file.close(true)
-            end
+            output = output_read.read
+            output_read.close
         end
 
         if arguments[:failonfail]
@@ -348,7 +319,7 @@ module Util
             end
         end
 
-        return output
+        output
     end
 
     module_function :execute