pkg/build: add build command for starnix

pkg/build/build.go

@@ -144,6 +144,8 @@ func getBuilder(targetOS, targetArch, vmType string) (builder, error) {
 			return cuttlefish{}, nil
 		} else if vmType == "proxyapp:android" {
 			return android{}, nil
+		} else if vmType == targets.Starnix {
+			return starnix{}, nil
 		}
 	}
 	builders := map[string]builder{

pkg/build/starnix.go

@@ -0,0 +1,116 @@
+// Copyright 2024 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+package build
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/google/syzkaller/pkg/osutil"
+	"github.com/google/syzkaller/sys/targets"
+	starnixVM "github.com/google/syzkaller/vm/starnix"
+)
+
+type starnix struct{}
+
+// The name of the Fuchsia assembly override defined in `overrideRule`.
+const overrideName = "syzkaller_starnix"
+
+// A Fuchsia assembly override definition adding a package containing fuzzing dependencies.
+var overrideRule = fmt.Sprintf(`import("//build/assembly/developer_overrides.gni")
+
+assembly_developer_overrides("%s") {
+    testonly = true
+    base_packages = [
+        "//src/testing/fuzzing/syzkaller/starnix:syzkaller_starnix",
+    ]
+}
+`, overrideName)
+
+func (st starnix) build(params Params) (ImageDetails, error) {
+	sysTarget := targets.Get(targets.Linux, params.TargetArch)
+	arch := sysTarget.KernelArch
+	if arch != "x86_64" {
+		return ImageDetails{}, fmt.Errorf("unsupported starnix arch %v", arch)
+	}
+	arch = "x64"
+	product := fmt.Sprintf("%s.%s", "workbench_eng", arch)
+
+	localDir := filepath.Join(params.KernelDir, "local")
+	if err := os.MkdirAll(filepath.Join(params.KernelDir, "local"), 0750); err != nil {
+		return ImageDetails{}, err
+	}
+	if err := osutil.SandboxChown(localDir); err != nil {
+		return ImageDetails{}, err
+	}
+	overridePath := filepath.Join(localDir, "BUILD.gn")
+	if err := os.WriteFile(overridePath, []byte(overrideRule), 0660); err != nil {
+		return ImageDetails{}, err
+	}
+	if err := osutil.SandboxChown(overridePath); err != nil {
+		return ImageDetails{}, err
+	}
+	if _, err := runSandboxed(
+		time.Hour,
+		params.KernelDir,
+		"scripts/fx", "--dir", "out/"+arch,
+		"set", product,
+		"--assembly-override", fmt.Sprintf("'//products/workbench/*=//local:%s'", overrideName),
+	); err != nil {
+		return ImageDetails{}, err
+	}
+
+	imageFilePath := filepath.Join(params.OutputDir, "image")
+	imageFile, err := os.Create(imageFilePath)
+	if err != nil {
+		return ImageDetails{}, fmt.Errorf("failed to create output file: %w", err)
+	}
+	defer imageFile.Close()
+
+	if _, err := runSandboxed(time.Hour*2, params.KernelDir, "scripts/fx", "build"); err != nil {
+		return ImageDetails{}, err
+	}
+	ffxBinary, err := starnixVM.GetToolPath(params.KernelDir, "ffx")
+	if err != nil {
+		return ImageDetails{}, err
+	}
+	productBundlePathRaw, err := runSandboxed(
+		30*time.Second,
+		params.KernelDir,
+		ffxBinary,
+		"config", "get", "product.path",
+	)
+	if err != nil {
+		return ImageDetails{}, nil
+	}
+	productBundlePath := strings.Trim(string(productBundlePathRaw), "\"")
+	fxfsPath, err := runSandboxed(
+		30*time.Second,
+		params.KernelDir,
+		ffxBinary,
+		"product", "get-image-path", productBundlePath,
+		"--slot", "a",
+		"--image-type", "fxfs",
+	)
+	if err != nil {
+		return ImageDetails{}, nil
+	}
+	if err := osutil.CopyFile(string(fxfsPath), imageFilePath); err != nil {
+		return ImageDetails{}, err
+	}
+	return ImageDetails{}, nil
+}
+
+func (st starnix) clean(kernelDir, targetArch string) error {
+	_, err := runSandboxed(
+		time.Hour,
+		kernelDir,
+		"scripts/fx", "--dir", "out/"+targetArch,
+		"clean",
+	)
+	return err
+}

pkg/instance/instance.go

@@ -171,7 +171,9 @@ func (env *env) BuildKernel(buildCfg *BuildKernelConfig) (
 }
 
 func SetConfigImage(cfg *mgrconfig.Config, imageDir string, reliable bool) error {
-	cfg.KernelObj = filepath.Join(imageDir, "obj")
+	if cfg.Type != targets.Starnix {
+		cfg.KernelObj = filepath.Join(imageDir, "obj")
+	}
 	cfg.Image = filepath.Join(imageDir, "image")
 	if keyFile := filepath.Join(imageDir, "key"); osutil.IsExist(keyFile) {
 		cfg.SSHKey = keyFile

pkg/vcs/fuchsia.go

@@ -24,9 +24,9 @@ func newFuchsia(dir string, opts []RepoOpt) *fuchsia {
 }
 
 func (ctx *fuchsia) Poll(repo, branch string) (*Commit, error) {
-	if repo != "https://fuchsia.googlesource.com" || branch != "master" {
+	if repo != "https://fuchsia.googlesource.com/fuchsia" || branch != "master" {
 		// Fuchsia ecosystem is hard-wired to the main repo.
-		return nil, fmt.Errorf("fuchsia: can only check out https://fuchsia.googlesource.com/master")
+		return nil, fmt.Errorf("fuchsia: can only check out https://fuchsia.googlesource.com/fuchsia/+/master")
 	}
 	if _, err := runSandboxed(ctx.dir, "./.jiri_root/bin/jiri", "update"); err != nil {
 		if err := ctx.initRepo(); err != nil {

pkg/vcs/vcs.go

@@ -192,6 +192,9 @@ const (
 func NewRepo(os, vmType, dir string, opts ...RepoOpt) (Repo, error) {
 	switch os {
 	case targets.Linux:
+		if vmType == targets.Starnix {
+			return newFuchsia(dir, opts), nil
+		}
 		return newLinux(dir, opts, vmType), nil
 	case targets.Fuchsia:
 		return newFuchsia(dir, opts), nil

vm/starnix/starnix.go

@@ -102,7 +102,7 @@ func (pool *Pool) Create(workdir string, index int) (vmimpl.Instance, error) {
 	}()
 
 	var err error
-	inst.ffxBinary, err = getToolPath(inst.fuchsiaDirectory, "ffx")
+	inst.ffxBinary, err = GetToolPath(inst.fuchsiaDirectory, "ffx")
 	if err != nil {
 		return nil, err
 	}
@@ -454,7 +454,7 @@ type toolMetadata struct {
 }
 
 // Resolve a tool by name using tool_paths.json in the build dir.
-func getToolPath(fuchsiaDir, toolName string) (string, error) {
+func GetToolPath(fuchsiaDir, toolName string) (string, error) {
 	buildDir, err := getFuchsiaBuildDir(fuchsiaDir)
 	if err != nil {
 		return "", err