pkg/build: add build command for starnix

Co-authored-by: eep@google.com

4 files changed, 128 insertions, 4 deletions

diff --git a/pkg/build/build.go b/pkg/build/build.go
index c9a5b038f..86906a0f7 100644
--- a/pkg/build/build.go
+++ b/pkg/build/build.go
@@ -162,6 +162,8 @@ 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{
diff --git a/pkg/build/starnix.go b/pkg/build/starnix.go
new file mode 100644
index 000000000..e629c004e
--- /dev/null
+++ b/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"), 0755); 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 := osutil.SandboxChown(localDir); 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
+	}
+
+	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,
+		"-c", "log.enabled=false,ffx.analytics.disabled=true,daemon.autostart=false",
+		"config", "get", "product.path",
+	)
+	if err != nil {
+		return ImageDetails{}, err
+	}
+	productBundlePath := strings.Trim(string(productBundlePathRaw), "\"\n")
+	fxfsPathRaw, err := runSandboxed(
+		30*time.Second,
+		params.KernelDir,
+		ffxBinary,
+		"-c", "log.enabled=false,ffx.analytics.disabled=true,daemon.autostart=false",
+		"product", "get-image-path", productBundlePath,
+		"--slot", "a",
+		"--image-type", "fxfs",
+	)
+	if err != nil {
+		return ImageDetails{}, err
+	}
+	fxfsPath := strings.Trim(string(fxfsPathRaw), "\"\n")
+	if err := osutil.CopyFile(fxfsPath, filepath.Join(params.OutputDir, "image")); err != nil {
+		return ImageDetails{}, err
+	}
+	kernelObjPath := filepath.Join(params.KernelDir, "out", arch, "exe.unstripped", "starnix_kernel")
+	if err := osutil.CopyFile(kernelObjPath, filepath.Join(params.OutputDir, "obj", "vmlinux")); err != nil {
+		return ImageDetails{}, err
+	}
+	return ImageDetails{}, nil
+}
+
+func (st starnix) clean(params Params) error {
+	_, err := runSandboxed(
+		time.Hour,
+		params.KernelDir,
+		"scripts/fx", "--dir", "out/"+params.TargetArch,
+		"clean",
+	)
+	return err
+}
diff --git a/pkg/vcs/fuchsia.go b/pkg/vcs/fuchsia.go
index dfe4dc597..c2704c8ea 100644
--- a/pkg/vcs/fuchsia.go
+++ b/pkg/vcs/fuchsia.go
@@ -24,9 +24,12 @@ func newFuchsia(dir string, opts []RepoOpt) *fuchsia {
 }
 
 func (ctx *fuchsia) Poll(repo, branch string) (*Commit, error) {
-	if repo != "https://fuchsia.googlesource.com" || 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")
+	if repo != "https://fuchsia.googlesource.com/fuchsia" || (branch != "main" && branch != "master") {
+		// Fuchsia ecosystem is hard-wired to the main repo + branch.
+		// The 'master' branch is a mirror of 'main'.
+		return nil, fmt.Errorf(
+			"fuchsia: can only check out 'main' or 'master' branch of https://fuchsia.googlesource.com/fuchsia",
+		)
 	}
 	if _, err := runSandboxed(ctx.dir, "./.jiri_root/bin/jiri", "update"); err != nil {
 		if err := ctx.initRepo(); err != nil {
@@ -48,7 +51,7 @@ func (ctx *fuchsia) initRepo() error {
 	if err := osutil.SandboxChown(tmpDir); err != nil {
 		return err
 	}
-	cmd := "curl -s 'https://fuchsia.googlesource.com/fuchsia/+/master/scripts/bootstrap?format=TEXT' |" +
+	cmd := "curl -s 'https://fuchsia.googlesource.com/fuchsia/+/main/scripts/bootstrap?format=TEXT' |" +
 		"base64 --decode | bash"
 	if _, err := runSandboxed(tmpDir, "bash", "-c", cmd); err != nil {
 		return err
diff --git a/pkg/vcs/vcs.go b/pkg/vcs/vcs.go
index 17f54d653..cb32a4071 100644
--- a/pkg/vcs/vcs.go
+++ b/pkg/vcs/vcs.go
@@ -197,6 +197,9 @@ 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