pkg/invoke: refactor plugin exec and backfill unit tests

invoke/raw_exec.go

@@ -0,0 +1,63 @@
+// Copyright 2016 CNI authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package invoke
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"os/exec"
+
+	"github.com/containernetworking/cni/pkg/types"
+)
+
+type RawExec struct {
+	Stderr io.Writer
+}
+
+func (e *RawExec) ExecPlugin(pluginPath string, stdinData []byte, environ []string) ([]byte, error) {
+	stdout := &bytes.Buffer{}
+
+	c := exec.Cmd{
+		Env:    environ,
+		Path:   pluginPath,
+		Args:   []string{pluginPath},
+		Stdin:  bytes.NewBuffer(stdinData),
+		Stdout: stdout,
+		Stderr: e.Stderr,
+	}
+	if err := c.Run(); err != nil {
+		return nil, pluginErr(err, stdout.Bytes())
+	}
+
+	return stdout.Bytes(), nil
+}
+
+func pluginErr(err error, output []byte) error {
+	if _, ok := err.(*exec.ExitError); ok {
+		emsg := types.Error{}
+		if perr := json.Unmarshal(output, &emsg); perr != nil {
+			return fmt.Errorf("netplugin failed but error parsing its diagnostic message %q: %v", string(output), perr)
+		}
+		details := ""
+		if emsg.Details != "" {
+			details = fmt.Sprintf("; %v", emsg.Details)
+		}
+		return fmt.Errorf("%v%v", emsg.Msg, details)
+	}
+
+	return err
+}