fix(pkg/driverbuilder): fix local executor to correctly fetch KERNELDIR.

Signed-off-by: Federico Di Pierro <nierro92@gmail.com>

Author: FedeDP

pkg/driverbuilder/local.go

@@ -2,6 +2,7 @@ package driverbuilder
 
 import (
 	"bufio"
+	"bytes"
 	"context"
 	_ "embed"
 	"errors"
@@ -13,7 +14,6 @@ import (
 	"os/exec"
 	"os/user"
 	"path/filepath"
-	"strings"
 	"time"
 )
 
@@ -67,24 +67,35 @@ func (lbp *LocalBuildProcessor) Start(b *builder.Build) error {
 		// if an unsupported target is passed.
 		// Go on skipping automatic kernel headers download.
 		if err == nil {
-			slog.Info("Trying automatic kernel headers download.")
+			slog.Info("Trying automatic kernel headers download")
 			kernelDownloadScript, err := builder.KernelDownloadScript(realBuilder, nil, kr)
+			// Patch kernel download script to echo KERNELDIR.
+			// We need to capture KERNELDIR to later pass it as env variable to the build.
+			kernelDownloadScript += "\necho $KERNELDIR"
 			if err == nil {
 				out, err := exec.Command("bash", "-c", kernelDownloadScript).Output()
 				if err == nil {
-					path := strings.TrimSuffix(string(out), "\n")
+					// Scan all stdout line by line and
+					// store last line as KERNELDIR path.
+					reader := bytes.NewReader(out)
+					scanner := bufio.NewScanner(reader)
+					var path string
+					for scanner.Scan() {
+						path = scanner.Text()
+					}
+					slog.Info("Setting KERNELDIR env var", "path", path)
 					// add the kerneldir path to env
 					lbp.envMap[kernelDirEnv] = path
 					defer func() {
 						_ = os.RemoveAll("/tmp/kernel-download")
 						_ = os.RemoveAll(path)
 					}()
 				} else {
-					slog.Warn("Failed to download headers.", "err", err)
+					slog.Warn("Failed to download headers", "err", err)
 				}
 			}
 		} else {
-			slog.Info("Skipping kernel headers automatic download.", "err", err)
+			slog.Info("Skipping kernel headers automatic download", "err", err)
 		}
 	}
 
@@ -137,7 +148,7 @@ func (lbp *LocalBuildProcessor) Start(b *builder.Build) error {
 	srcProbePath := vv.GetProbeFullPath(c)
 
 	if len(lbp.srcDir) == 0 {
-		slog.Info("Downloading driver sources.")
+		slog.Info("Downloading driver sources")
 		// Download src!
 		libsDownloadScript, err := builder.LibsDownloadScript(c)
 		if err != nil {
@@ -168,14 +179,14 @@ func (lbp *LocalBuildProcessor) Start(b *builder.Build) error {
 
 		stdout, err := cmd.StdoutPipe()
 		if err != nil {
-			slog.Warn("Failed to pipe stdout. Trying without piping.", "err", err)
+			slog.Warn("Failed to pipe stdout", "err", err)
 			_, err = cmd.CombinedOutput()
 		} else {
 			cmd.Stderr = cmd.Stdout // redirect stderr to stdout so that we catch it
 			defer stdout.Close()
 			err = cmd.Start()
 			if err != nil {
-				slog.Warn("Failed to execute command.", "err", err)
+				slog.Warn("Failed to execute command", "err", err)
 			} else {
 				// print the output of the subprocess line by line
 				scanner := bufio.NewScanner(stdout)