github.com/coreos/mantle@v0.13.0/system/exec/exec.go (about)

     1  // Copyright 2015 CoreOS, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // exec is extension of the standard os.exec package.
    16  // Adds a handy dandy interface and assorted other features.
    17  package exec
    18  
    19  import (
    20  	"context"
    21  	"io"
    22  	"os/exec"
    23  	"syscall"
    24  )
    25  
    26  var (
    27  	// for equivalence with os/exec
    28  	ErrNotFound = exec.ErrNotFound
    29  	LookPath    = exec.LookPath
    30  )
    31  
    32  // An exec.Cmd compatible interface.
    33  type Cmd interface {
    34  	// Methods provided by exec.Cmd
    35  	CombinedOutput() ([]byte, error)
    36  	Output() ([]byte, error)
    37  	Run() error
    38  	Start() error
    39  	StderrPipe() (io.ReadCloser, error)
    40  	StdinPipe() (io.WriteCloser, error)
    41  	StdoutPipe() (io.ReadCloser, error)
    42  	Wait() error
    43  
    44  	// Simplified wrapper for Process.Kill + Wait
    45  	Kill() error
    46  
    47  	// Simplified wrapper for Process.Pid
    48  	Pid() int
    49  }
    50  
    51  // Basic Cmd implementation based on exec.Cmd
    52  type ExecCmd struct {
    53  	*exec.Cmd
    54  	cancel context.CancelFunc
    55  }
    56  
    57  func Command(name string, arg ...string) *ExecCmd {
    58  	return CommandContext(context.Background(), name, arg...)
    59  }
    60  
    61  func CommandContext(ctx context.Context, name string, arg ...string) *ExecCmd {
    62  	ctx, cancel := context.WithCancel(ctx)
    63  	return &ExecCmd{
    64  		Cmd:    exec.CommandContext(ctx, name, arg...),
    65  		cancel: cancel,
    66  	}
    67  }
    68  
    69  func (cmd *ExecCmd) Kill() error {
    70  	cmd.cancel()
    71  	err := cmd.Wait()
    72  	if err == nil {
    73  		return nil
    74  	}
    75  
    76  	if eerr, ok := err.(*exec.ExitError); ok {
    77  		status := eerr.Sys().(syscall.WaitStatus)
    78  		if status.Signal() == syscall.SIGKILL {
    79  			return nil
    80  		}
    81  	}
    82  
    83  	return err
    84  }
    85  
    86  func (cmd *ExecCmd) Pid() int {
    87  	return cmd.Process.Pid
    88  }
    89  
    90  // IsCmdNotFound reports true if the underlying error was exec.ErrNotFound.
    91  func IsCmdNotFound(err error) bool {
    92  	if eerr, ok := err.(*exec.Error); ok && eerr.Err == ErrNotFound {
    93  		return true
    94  	}
    95  	return false
    96  }