pkg/aflow/action/kernel: add checkout action

1 files changed, 90 insertions, 0 deletions

diff --git a/pkg/aflow/action/kernel/checkout.go b/pkg/aflow/action/kernel/checkout.go
new file mode 100644
index 000000000..397412393
--- /dev/null
+++ b/pkg/aflow/action/kernel/checkout.go
@@ -0,0 +1,90 @@
+// Copyright 2025 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 kernel
+
+import (
+	"path/filepath"
+	"sync"
+	"time"
+
+	"github.com/google/syzkaller/pkg/aflow"
+	"github.com/google/syzkaller/pkg/osutil"
+	"github.com/google/syzkaller/pkg/vcs"
+	"github.com/google/syzkaller/sys/targets"
+)
+
+// Checkout action checks out the Linux kernel on the given commit,
+// outputs the source directory with the checkout.
+var Checkout = aflow.NewFuncAction("kernel-checkouter", checkout)
+
+type checkoutArgs struct {
+	KernelRepo   string
+	KernelCommit string
+}
+
+type checkoutResult struct {
+	// Directory with the checked out sources.
+	KernelSrc string
+}
+
+func checkout(ctx *aflow.Context, args checkoutArgs) (checkoutResult, error) {
+	var res checkoutResult
+	err := UseLinuxRepo(ctx, func(kernelRepoDir string, repo vcs.Repo) error {
+		dir, err := ctx.Cache("src", args.KernelCommit, func(dir string) error {
+			if _, err := repo.SwitchCommit(args.KernelCommit); err != nil {
+				if _, err := repo.CheckoutCommit(args.KernelRepo, args.KernelCommit); err != nil {
+					return err
+				}
+			}
+			// The following commit breaks compile_commands.json by adding bogus commands that fail.
+			// There is no easy way to filter out these bogus commands, so we revert the commit.
+			const (
+				// scripts/clang-tools: Handle included .c files in gen_compile_commands
+				badCommit = "9362d34acf91a706c543d919ade3e651b9bd2d6f"
+				// Revert "scripts/clang-tools: Handle included .c files in gen_compile_commands"
+				revertCommit = "07fe35b766a6fcd4ec8214e5066b7b0056b6ec6a"
+			)
+
+			if ok, err := repo.Contains(revertCommit); err != nil {
+				return err
+			} else if !ok {
+				if ok, err := repo.Contains(badCommit); err != nil {
+					return err
+				} else if ok {
+					if _, err = osutil.RunCmd(time.Hour, kernelRepoDir,
+						"git", "revert", "--no-edit", badCommit); err != nil {
+						return err
+					}
+				}
+			}
+			if _, err := osutil.RunCmd(time.Hour, dir, "git", "init"); err != nil {
+				return err
+			}
+			if _, err := osutil.RunCmd(time.Hour, dir, "git", "remote", "add", "origin", kernelRepoDir); err != nil {
+				return err
+			}
+			if _, err := osutil.RunCmd(time.Hour, dir, "git", "pull", "origin", "HEAD", "--depth=1",
+				"--allow-unrelated-histories"); err != nil {
+				return err
+			}
+			return nil
+		})
+		res.KernelSrc = dir
+		return err
+	})
+	return res, err
+}
+
+var repoMu sync.Mutex
+
+func UseLinuxRepo(ctx *aflow.Context, fn func(string, vcs.Repo) error) error {
+	repoMu.Lock()
+	defer repoMu.Unlock()
+	kernelRepoDir := filepath.Join(ctx.Workdir, "repo", targets.Linux)
+	repo, err := vcs.NewRepo(targets.Linux, "", kernelRepoDir)
+	if err != nil {
+		return err
+	}
+	return fn(kernelRepoDir, repo)
+}