pkg/build: added feature to copy kernel image for netbsd

* Modified pkg/build/netbsd.go
1. Made kernel build incremental
2. Added code to copy kernel to disk image

* Fix formating issues

* Fixed basic issues

* Fixed copy kernel to disk
1. Added CPU option to default
2. Added snapshot option to vm/qemu/qemu.go
3. Hacky solution to get the build working

* Fixed issues and added vm.MonitorExecution

* Added sync instead of poweroff

2 files changed, 73 insertions, 10 deletions

diff --git a/pkg/build/build.go b/pkg/build/build.go
index 64f32f29e..130a4108a 100644
--- a/pkg/build/build.go
+++ b/pkg/build/build.go
@@ -74,7 +74,7 @@ func getBuilder(targetOS, targetArch, vmType string) (builder, error) {
 		return akaros{}, nil
 	case targetOS == "openbsd" && targetArch == "amd64" && (vmType == "gce" || vmType == "vmm"):
 		return openbsd{}, nil
-	case targetOS == "netbsd" && targetArch == "amd64" && vmType == "qemu":
+	case targetOS == "netbsd" && targetArch == "amd64" && (vmType == "qemu" || vmType == "gce"):
 		return netbsd{}, nil
 	default:
 		return nil, fmt.Errorf("unsupported image type %v/%v/%v", targetOS, targetArch, vmType)
diff --git a/pkg/build/netbsd.go b/pkg/build/netbsd.go
index cab291119..31d44598a 100644
--- a/pkg/build/netbsd.go
+++ b/pkg/build/netbsd.go
@@ -4,13 +4,17 @@
 package build
 
 import (
+	"encoding/json"
 	"fmt"
 	"path/filepath"
 	"runtime"
 	"strconv"
 	"time"
 
+	"github.com/google/syzkaller/pkg/mgrconfig"
 	"github.com/google/syzkaller/pkg/osutil"
+	"github.com/google/syzkaller/pkg/report"
+	"github.com/google/syzkaller/vm"
 )
 
 type netbsd struct{}
@@ -33,29 +37,33 @@ no options SVS
 	if err := osutil.WriteFile(filepath.Join(confDir, kernelName), conf); err != nil {
 		return err
 	}
-
 	// Build tools before building kernel
 	if _, err := osutil.RunCmd(10*time.Minute, kernelDir, "./build.sh", "-m", targetArch,
-		"-U", "-j"+strconv.Itoa(runtime.NumCPU()), "tools"); err != nil {
+		"-U", "-u", "-j"+strconv.Itoa(runtime.NumCPU()), "tools"); err != nil {
 		return extractRootCause(err)
 	}
 
 	// Build kernel
 	if _, err := osutil.RunCmd(10*time.Minute, kernelDir, "./build.sh", "-m", targetArch,
-		"-U", "-j"+strconv.Itoa(runtime.NumCPU()), "kernel="+kernelName); err != nil {
+		"-U", "-u", "-j"+strconv.Itoa(runtime.NumCPU()), "kernel="+kernelName); err != nil {
 		return extractRootCause(err)
 	}
-
-	for _, s := range []struct{ dir, src, dst string }{
-		{compileDir, "netbsd", "kernel"},
-		{compileDir, "netbsd.gdb", "netbsd.gdb"},
+	for _, s := range []struct{ dir, obj string }{
+		{compileDir, "netbsd"},
+		{compileDir, "netbsd.gdb"},
+		{userspaceDir, "image"},
+		{userspaceDir, "key"},
 	} {
-		fullSrc := filepath.Join(s.dir, s.src)
-		fullDst := filepath.Join(outputDir, s.dst)
+		fullSrc := filepath.Join(s.dir, s.obj)
+		fullDst := filepath.Join(outputDir, s.obj)
 		if err := osutil.CopyFile(fullSrc, fullDst); err != nil {
 			return fmt.Errorf("failed to copy %v -> %v: %v", fullSrc, fullDst, err)
 		}
 	}
+
+	if vmType == "qemu" || vmType == "gce" {
+		return CopyKernelToDisk(outputDir)
+	}
 	return nil
 }
 
@@ -66,3 +74,58 @@ func (ctx netbsd) clean(kernelDir string) error {
 	// machine.
 	return nil
 }
+
+// Copy the compiled kernel to the qemu disk image using ssh
+func CopyKernelToDisk(outputDir string) error {
+	temp := []byte(`
+{
+	"snapshot": false,
+	"mem": 1024
+}	`)
+	VMconfig := (*json.RawMessage)(&temp)
+	// Create config for booting the disk image
+	cfg := &mgrconfig.Config{
+		Workdir:      outputDir,
+		Image:        filepath.Join(outputDir, "image"),
+		SSHKey:       filepath.Join(outputDir, "key"),
+		SSHUser:      "root",
+		TargetOS:     "netbsd",
+		TargetArch:   "amd64",
+		TargetVMArch: "amd64",
+		Type:         "qemu",
+		VM:           *VMconfig,
+	}
+	// Create a VM pool
+	pool, err := vm.Create(cfg, false)
+	if err != nil {
+		return fmt.Errorf("failed to create a VM Pool : %v", err)
+	}
+	// Create a new reporter instance
+	reporter, err := report.NewReporter(cfg)
+	if err != nil {
+		return fmt.Errorf("failed to create a Reporter : %v", err)
+	}
+	// Create a VM instance (We need only one)
+	inst, err := pool.Create(0)
+	if err != nil {
+		return fmt.Errorf("failed to create the VM Instance : %v", err)
+	}
+	defer inst.Close()
+	// Copy the kernel into the disk image and replace it
+	// This makes use of the fact that the file is copied by default to /
+	kernel, err := inst.Copy(filepath.Join(outputDir, "netbsd"))
+	if err != nil {
+		return fmt.Errorf("error Copying the kernel %v: %v", kernel, err)
+	}
+	// Run sync so that the copied image is stored properly
+	outc, errc, err := inst.Run(time.Minute, nil, "sync")
+	if err != nil {
+		return fmt.Errorf("error syncing the instance %v", err)
+	}
+	// Make sure that the command has executed properly
+	rep := inst.MonitorExecution(outc, errc, reporter, vm.ExitNormal)
+	if rep != nil {
+		return fmt.Errorf("error executng poweroff : %v", rep.Title)
+	}
+	return nil
+}