Module: Ohai::Mixin::Command

Included in:
System
Defined in:
lib/ohai/mixin/command.rb

Class Method Summary collapse

Class Method Details

.popen4(cmd, args = {}, &b) ⇒ Object

This is taken directly from Ara T Howard’s Open4 library, and then modified to suit the needs of Ohai. Any bugs here are most likely my own, and not Ara’s.

The original appears in external/open4.rb in its unmodified form.

Thanks Ara!



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# File 'lib/ohai/mixin/command.rb', line 102

def popen4(cmd, args={}, &b)
  
  args[:user] ||= nil
  unless args[:user].kind_of?(Integer)
    args[:user] = Etc.getpwnam(args[:user]).uid if args[:user]
  end
  args[:group] ||= nil
  unless args[:group].kind_of?(Integer)
    args[:group] = Etc.getgrnam(args[:group]).gid if args[:group]
  end
  args[:environment] ||= nil
  
  pw, pr, pe, ps = IO.pipe, IO.pipe, IO.pipe, IO.pipe

  verbose = $VERBOSE
  begin
    $VERBOSE = nil
    ps.last.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC)

    cid = fork {
      pw.last.close
      STDIN.reopen pw.first
      pw.first.close

      pr.first.close
      STDOUT.reopen pr.last
      pr.last.close

      pe.first.close
      STDERR.reopen pe.last
      pe.last.close

      STDOUT.sync = STDERR.sync = true

      if args[:user]
        Process.euid = args[:user]
        Process.uid = args[:user]
      end
      
      if args[:group]
        Process.egid = args[:group]
        Process.gid = args[:group]
      end
      
      if args[:environment]
        args[:environment].each do |key,value|
          ENV[key] = value
        end
      end
      
      begin
        if cmd.kind_of?(Array)
          exec(*cmd)
        else
          exec(cmd)
        end
        raise 'forty-two' 
      rescue Exception => e
        Marshal.dump(e, ps.last)
        ps.last.flush
      end
      ps.last.close unless (ps.last.closed?)
      exit!
    }
  ensure
    $VERBOSE = verbose
  end

  [pw.first, pr.last, pe.last, ps.last].each{|fd| fd.close}

  begin
    e = Marshal.load ps.first
    # If we get here, exec failed. Collect status of child to prevent
    # zombies.
    Process.waitpid(cid)
    raise(Exception === e ? e : "unknown failure!")
  rescue EOFError # If we get an EOF error, then the exec was successful
    42
  ensure
    ps.first.close
  end

  pw.last.sync = true

  pi = [pw.last, pr.first, pe.first]

  if b 
    begin
      b[cid, *pi]
      Process.waitpid2(cid).last
    ensure
      pi.each{|fd| fd.close unless fd.closed?}
    end
  else
    [cid, pw.last, pr.first, pe.first]
  end
end

.run_command(args = {}) ⇒ Object 



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# File 'lib/ohai/mixin/command.rb', line 34

def run_command(args={})         
  if args.has_key?(:creates)
    if File.exists?(args[:creates])
      Ohai::Log.debug("Skipping #{args[:command]} - creates #{args[:creates]} exists.")
      return false
    end
  end
  
  stdout_string = nil
  stderr_string = nil
          
  args[:cwd] ||= Dir.tmpdir        
  unless File.directory?(args[:cwd])
    raise Ohai::Exceptions::Exec, "#{args[:cwd]} does not exist or is not a directory"
  end
  
  status = nil
  Dir.chdir(args[:cwd]) do
    if args[:timeout]
      begin
        Timeout.timeout(args[:timeout]) do
          status, stdout_string, stderr_string = systemu(args[:command])
        end
      rescue Exception => e
        Ohai::Log.error("#{args[:command_string]} exceeded timeout #{args[:timeout]}")
        raise(e)
      end
    else
      status, stdout_string, stderr_string = systemu(args[:command])
    end

    # systemu returns 42 when it hits unexpected errors
    if status.exitstatus == 42 and stderr_string == ""
      stderr_string = "Failed to run: #{args[:command]}, assuming command not found"
      Ohai::Log.debug(stderr_string)          
    end

    if stdout_string
      Ohai::Log.debug("---- Begin #{args[:command]} STDOUT ----")
      Ohai::Log.debug(stdout_string.strip)
      Ohai::Log.debug("---- End #{args[:command]} STDOUT ----")
    end
    if stderr_string
      Ohai::Log.debug("---- Begin #{args[:command]} STDERR ----")
      Ohai::Log.debug(stderr_string.strip)
      Ohai::Log.debug("---- End #{args[:command]} STDERR ----")
    end
  
    args[:returns] ||= 0
    args[:no_status_check] ||= false
    if status.exitstatus != args[:returns] and not args[:no_status_check]
      raise Ohai::Exceptions::Exec, "#{args[:command_string]} returned #{status.exitstatus}, expected #{args[:returns]}"
    else
      Ohai::Log.debug("Ran #{args[:command_string]} (#{args[:command]}) returned #{status.exitstatus}")
    end
  end
  return status, stdout_string, stderr_string
end