github.com/jk-he/cni@v0.8.1/pkg/invoke/raw_exec.go (about)

     1  // Copyright 2016 CNI authors
     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  package invoke
    16  
    17  import (
    18  	"bytes"
    19  	"context"
    20  	"encoding/json"
    21  	"fmt"
    22  	"io"
    23  	"os/exec"
    24  	"strings"
    25  	"time"
    26  
    27  	"github.com/containernetworking/cni/pkg/types"
    28  )
    29  
    30  type RawExec struct {
    31  	Stderr io.Writer
    32  }
    33  
    34  func (e *RawExec) ExecPlugin(ctx context.Context, pluginPath string, stdinData []byte, environ []string) ([]byte, error) {
    35  	stdout := &bytes.Buffer{}
    36  	stderr := &bytes.Buffer{}
    37  	c := exec.CommandContext(ctx, pluginPath)
    38  	c.Env = environ
    39  	c.Stdin = bytes.NewBuffer(stdinData)
    40  	c.Stdout = stdout
    41  	c.Stderr = stderr
    42  
    43  	// Retry the command on "text file busy" errors
    44  	for i := 0; i <= 5; i++ {
    45  		err := c.Run()
    46  
    47  		// Command succeeded
    48  		if err == nil {
    49  			break
    50  		}
    51  
    52  		// If the plugin is currently about to be written, then we wait a
    53  		// second and try it again
    54  		if strings.Contains(err.Error(), "text file busy") {
    55  			time.Sleep(time.Second)
    56  			continue
    57  		}
    58  
    59  		// All other errors except than the busy text file
    60  		return nil, e.pluginErr(err, stdout.Bytes(), stderr.Bytes())
    61  	}
    62  
    63  	// Copy stderr to caller's buffer in case plugin printed to both
    64  	// stdout and stderr for some reason. Ignore failures as stderr is
    65  	// only informational.
    66  	if e.Stderr != nil && stderr.Len() > 0 {
    67  		_, _ = stderr.WriteTo(e.Stderr)
    68  	}
    69  	return stdout.Bytes(), nil
    70  }
    71  
    72  func (e *RawExec) pluginErr(err error, stdout, stderr []byte) error {
    73  	emsg := types.Error{}
    74  	if len(stdout) == 0 {
    75  		if len(stderr) == 0 {
    76  			emsg.Msg = fmt.Sprintf("netplugin failed with no error message: %v", err)
    77  		} else {
    78  			emsg.Msg = fmt.Sprintf("netplugin failed: %q", string(stderr))
    79  		}
    80  	} else if perr := json.Unmarshal(stdout, &emsg); perr != nil {
    81  		emsg.Msg = fmt.Sprintf("netplugin failed but error parsing its diagnostic message %q: %v", string(stdout), perr)
    82  	}
    83  	return &emsg
    84  }
    85  
    86  func (e *RawExec) FindInPath(plugin string, paths []string) (string, error) {
    87  	return FindInPath(plugin, paths)
    88  }