github.com/phobos182/packer@v0.2.3-0.20130819023704-c84d2aeffc68/builder/amazon/chroot/communicator.go (about)

     1  package chroot
     2  
     3  import (
     4  	"github.com/mitchellh/packer/packer"
     5  	"io"
     6  	"log"
     7  	"os"
     8  	"os/exec"
     9  	"path/filepath"
    10  	"syscall"
    11  )
    12  
    13  // Communicator is a special communicator that works by executing
    14  // commands locally but within a chroot.
    15  type Communicator struct {
    16  	Chroot string
    17  }
    18  
    19  func (c *Communicator) Start(cmd *packer.RemoteCmd) error {
    20  	chrootCmdPath, err := exec.LookPath("chroot")
    21  	if err != nil {
    22  		return err
    23  	}
    24  
    25  	localCmd := exec.Command(chrootCmdPath, c.Chroot, "/bin/sh", "-c", cmd.Command)
    26  	localCmd.Stdin = cmd.Stdin
    27  	localCmd.Stdout = cmd.Stdout
    28  	localCmd.Stderr = cmd.Stderr
    29  	log.Printf("Executing: %s %#v", localCmd.Path, localCmd.Args)
    30  	if err := localCmd.Start(); err != nil {
    31  		return err
    32  	}
    33  
    34  	go func() {
    35  		exitStatus := 0
    36  		if err := localCmd.Wait(); err != nil {
    37  			if exitErr, ok := err.(*exec.ExitError); ok {
    38  				exitStatus = 1
    39  
    40  				// There is no process-independent way to get the REAL
    41  				// exit status so we just try to go deeper.
    42  				if status, ok := exitErr.Sys().(syscall.WaitStatus); ok {
    43  					exitStatus = status.ExitStatus()
    44  				}
    45  			}
    46  		}
    47  
    48  		log.Printf(
    49  			"Chroot executation ended with '%d': '%s'",
    50  			exitStatus, cmd.Command)
    51  		cmd.SetExited(exitStatus)
    52  	}()
    53  
    54  	return nil
    55  }
    56  
    57  func (c *Communicator) Upload(dst string, r io.Reader) error {
    58  	dst = filepath.Join(c.Chroot, dst)
    59  	log.Printf("Uploading to chroot dir: %s", dst)
    60  	f, err := os.Create(dst)
    61  	if err != nil {
    62  		return err
    63  	}
    64  	defer f.Close()
    65  
    66  	if _, err := io.Copy(f, r); err != nil {
    67  		return err
    68  	}
    69  
    70  	return nil
    71  }
    72  
    73  func (c *Communicator) Download(src string, w io.Writer) error {
    74  	src = filepath.Join(c.Chroot, src)
    75  	log.Printf("Downloading from chroot dir: %s", src)
    76  	f, err := os.Open(src)
    77  	if err != nil {
    78  		return err
    79  	}
    80  	defer f.Close()
    81  
    82  	if _, err := io.Copy(w, f); err != nil {
    83  		return err
    84  	}
    85  
    86  	return nil
    87  }