refactor: undo specific cmd invocation

src/environment.go

@@ -1,10 +1,10 @@
 package main
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"fmt"
-	"io"
 	"io/ioutil"
 	"log"
 	"net/http"
@@ -13,7 +13,6 @@ import (
 	"path/filepath"
 	"runtime"
 	"strings"
-	"sync"
 	"time"
 
 	"github.com/distatus/battery"
@@ -291,70 +290,19 @@ func (env *environment) runCommand(command string, args ...string) (string, erro
 	if cmd, ok := env.cmdCache.get(command); ok {
 		command = cmd
 	}
-	copyAndCapture := func(r io.Reader) ([]byte, error) {
-		var out []byte
-		buf := make([]byte, 1024)
-		for {
-			n, err := r.Read(buf)
-			if n > 0 {
-				d := buf[:n]
-				out = append(out, d...)
-			}
-			if err == nil {
-				continue
-			}
-			// Read returns io.EOF at the end of file, which is not an error for us
-			if err == io.EOF {
-				err = nil
-			}
-			return out, err
-		}
-	}
-	normalizeOutput := func(out []byte) string {
-		return strings.TrimSuffix(string(out), "\n")
-	}
 	cmd := exec.Command(command, args...)
-	var stdout, stderr []byte
-	var stdoutErr, stderrErr error
-	stdoutIn, _ := cmd.StdoutPipe()
-	stderrIn, _ := cmd.StderrPipe()
-	err := cmd.Start()
-	if err != nil {
-		errorStr := fmt.Sprintf("cmd.Start() failed with '%s'", err)
+	var out bytes.Buffer
+	var err bytes.Buffer
+	cmd.Stdout = &out
+	cmd.Stderr = &err
+	cmdErr := cmd.Run()
+	if cmdErr != nil {
+		output := err.String()
+		errorStr := fmt.Sprintf("cmd.Start() failed with '%s'", output)
 		env.log(Error, "runCommand", errorStr)
-		return "", errors.New(errorStr)
+		return output, cmdErr
 	}
-	// cmd.Wait() should be called only after we finish reading
-	// from stdoutIn and stderrIn.
-	// wg ensures that we finish
-	var wg sync.WaitGroup
-	wg.Add(1)
-	go func() {
-		stdout, stdoutErr = copyAndCapture(stdoutIn)
-		wg.Done()
-	}()
-	stderr, stderrErr = copyAndCapture(stderrIn)
-	wg.Wait()
-	err = cmd.Wait()
-	if err != nil {
-		env.log(Error, "runCommand", err.Error())
-		if exitErr, ok := err.(*exec.ExitError); ok {
-			return "", &commandError{
-				err:      exitErr.Error(),
-				exitCode: exitErr.ExitCode(),
-			}
-		}
-	}
-	if stdoutErr != nil || stderrErr != nil {
-		errString := "failed to capture stdout or stderr"
-		env.log(Error, "runCommand", errString)
-		return "", errors.New(errString)
-	}
-	stderrStr := normalizeOutput(stderr)
-	if len(stderrStr) > 0 {
-		return stderrStr, nil
-	}
-	output := normalizeOutput(stdout)
+	output := strings.TrimSuffix(out.String(), "\n")
 	env.log(Debug, "runCommand", output)
 	return output, nil
 }