github.phpd.cn/hashicorp/packer@v1.3.2/builder/amazon/chroot/step_flock.go (about)

     1  package chroot
     2  
     3  import (
     4  	"context"
     5  	"fmt"
     6  	"log"
     7  	"os"
     8  	"path/filepath"
     9  
    10  	"github.com/hashicorp/packer/helper/multistep"
    11  	"github.com/hashicorp/packer/packer"
    12  )
    13  
    14  // StepFlock provisions the instance within a chroot.
    15  //
    16  // Produces:
    17  //   flock_cleanup Cleanup - To perform early cleanup
    18  type StepFlock struct {
    19  	fh *os.File
    20  }
    21  
    22  func (s *StepFlock) Run(_ context.Context, state multistep.StateBag) multistep.StepAction {
    23  	ui := state.Get("ui").(packer.Ui)
    24  
    25  	lockfile := "/var/lock/packer-chroot/lock"
    26  	if err := os.MkdirAll(filepath.Dir(lockfile), 0755); err != nil {
    27  		err := fmt.Errorf("Error creating lock: %s", err)
    28  		state.Put("error", err)
    29  		ui.Error(err.Error())
    30  		return multistep.ActionHalt
    31  	}
    32  
    33  	log.Printf("Obtaining lock: %s", lockfile)
    34  	f, err := os.Create(lockfile)
    35  	if err != nil {
    36  		err := fmt.Errorf("Error creating lock: %s", err)
    37  		state.Put("error", err)
    38  		ui.Error(err.Error())
    39  		return multistep.ActionHalt
    40  	}
    41  
    42  	// LOCK!
    43  	if err := lockFile(f); err != nil {
    44  		err := fmt.Errorf("Error obtaining lock: %s", err)
    45  		state.Put("error", err)
    46  		ui.Error(err.Error())
    47  		return multistep.ActionHalt
    48  	}
    49  
    50  	// Set the file handle, we can't close it because we need to hold
    51  	// the lock.
    52  	s.fh = f
    53  
    54  	state.Put("flock_cleanup", s)
    55  	return multistep.ActionContinue
    56  }
    57  
    58  func (s *StepFlock) Cleanup(state multistep.StateBag) {
    59  	s.CleanupFunc(state)
    60  }
    61  
    62  func (s *StepFlock) CleanupFunc(state multistep.StateBag) error {
    63  	if s.fh == nil {
    64  		return nil
    65  	}
    66  
    67  	log.Printf("Unlocking: %s", s.fh.Name())
    68  	if err := unlockFile(s.fh); err != nil {
    69  		return err
    70  	}
    71  
    72  	s.fh = nil
    73  	return nil
    74  }