chore(deps): implement github.com/qdm12/golibs/command locally (#2418)

internal/command/start.go

@@ -0,0 +1,97 @@
+package command
+
+import (
+	"bufio"
+	"errors"
+	"io"
+	"os"
+	"os/exec"
+)
+
+// Start launches a command and streams stdout and stderr to channels.
+// All the channels returned are ready only and won't be closed
+// if the command fails later.
+func (c *Cmder) Start(cmd *exec.Cmd) (
+	stdoutLines, stderrLines <-chan string,
+	waitError <-chan error, startErr error) {
+	return start(cmd)
+}
+
+func start(cmd execCmd) (stdoutLines, stderrLines <-chan string,
+	waitError <-chan error, startErr error) {
+	stop := make(chan struct{})
+	stdoutReady := make(chan struct{})
+	stdoutLinesCh := make(chan string)
+	stdoutDone := make(chan struct{})
+	stderrReady := make(chan struct{})
+	stderrLinesCh := make(chan string)
+	stderrDone := make(chan struct{})
+
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	go streamToChannel(stdoutReady, stop, stdoutDone, stdout, stdoutLinesCh)
+
+	stderr, err := cmd.StderrPipe()
+	if err != nil {
+		_ = stdout.Close()
+		close(stop)
+		<-stdoutDone
+		return nil, nil, nil, err
+	}
+	go streamToChannel(stderrReady, stop, stderrDone, stderr, stderrLinesCh)
+
+	err = cmd.Start()
+	if err != nil {
+		_ = stdout.Close()
+		_ = stderr.Close()
+		close(stop)
+		<-stdoutDone
+		<-stderrDone
+		return nil, nil, nil, err
+	}
+
+	waitErrorCh := make(chan error)
+	go func() {
+		err := cmd.Wait()
+		_ = stdout.Close()
+		_ = stderr.Close()
+		close(stop)
+		<-stdoutDone
+		<-stderrDone
+		waitErrorCh <- err
+	}()
+
+	return stdoutLinesCh, stderrLinesCh, waitErrorCh, nil
+}
+
+func streamToChannel(ready chan<- struct{},
+	stop <-chan struct{}, done chan<- struct{},
+	stream io.Reader, lines chan<- string) {
+	defer close(done)
+	close(ready)
+	scanner := bufio.NewScanner(stream)
+	lineBuffer := make([]byte, bufio.MaxScanTokenSize) // 64KB
+	const maxCapacity = 20 * 1024 * 1024               // 20MB
+	scanner.Buffer(lineBuffer, maxCapacity)
+
+	for scanner.Scan() {
+		// scanner is closed if the context is canceled
+		// or if the command failed starting because the
+		// stream is closed (io.EOF error).
+		lines <- scanner.Text()
+	}
+	err := scanner.Err()
+	if err == nil || errors.Is(err, os.ErrClosed) {
+		return
+	}
+
+	// ignore the error if it is stopped.
+	select {
+	case <-stop:
+		return
+	default:
+		lines <- "stream error: " + err.Error()
+	}
+}