From 2d6db97b43c60c09c049ec804c57c308ca9bfbe8 Mon Sep 17 00:00:00 2001
From: Mikhail Klementev <blame@dumpstack.io>
Date: Thu, 16 Feb 2023 10:21:44 +0000
Subject: [PATCH] Add support for applying patches

---
 config/config.go |  8 +++++++
 gen.go           |  3 +++
 pew.go           | 58 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 69 insertions(+)

diff --git a/config/config.go b/config/config.go
index 09d076a..5fdc5cf 100644
--- a/config/config.go
+++ b/config/config.go
@@ -115,6 +115,12 @@ type FileTransfer struct {
 	Remote string
 }
 
+type Patch struct {
+	Path   string
+	Source string
+	Script string
+}
+
 // Artifact is for .out-of-tree.toml
 type Artifact struct {
 	Name             string
@@ -140,6 +146,8 @@ type Artifact struct {
 		DisableKpti  bool
 	}
 
+	Patches []Patch
+
 	Make struct {
 		Target string
 	}
diff --git a/gen.go b/gen.go
index d690fb6..5a55138 100644
--- a/gen.go
+++ b/gen.go
@@ -39,6 +39,9 @@ func genConfig(at config.ArtifactType) (err error) {
 	a.Preload = append(a.Preload, config.PreloadModule{
 		Repo: "Repo name (e.g. https://github.com/openwall/lkrg)",
 	})
+	a.Patches = append(a.Patches, config.Patch{
+		Path: "/path/to/profiling.patch",
+	})
 
 	buf, err := toml.Marshal(&a)
 	if err != nil {
diff --git a/pew.go b/pew.go
index d6968ca..2b1c2af 100644
--- a/pew.go
+++ b/pew.go
@@ -157,6 +157,59 @@ func dockerRun(timeout time.Duration, container, workdir, command string) (
 	return
 }
 
+func sh(workdir, cmd string) (output string, err error) {
+	command := exec.Command("sh", "-c", "cd "+workdir+" && "+cmd)
+	raw, err := command.CombinedOutput()
+	output = string(raw)
+	if err != nil {
+		e := fmt.Sprintf("%v %v output: %v", cmd, err, output)
+		err = errors.New(e)
+	}
+	return
+}
+
+func applyPatches(src string, ka config.Artifact) (err error) {
+	for i, patch := range ka.Patches {
+		name := fmt.Sprintf("patch_%02d", i)
+
+		path := src + "/" + name + ".diff"
+		if patch.Source != "" && patch.Path != "" {
+			err = errors.New("path and source are mutually exclusive")
+			return
+		} else if patch.Source != "" {
+			err = os.WriteFile(path, []byte(patch.Source), 0644)
+			if err != nil {
+				return
+			}
+		} else if patch.Path != "" {
+			err = copy.Copy(patch.Path, path)
+			if err != nil {
+				return
+			}
+		}
+
+		if patch.Source != "" || patch.Path != "" {
+			_, err = sh(src, "patch < "+path)
+			if err != nil {
+				return
+			}
+		}
+
+		if patch.Script != "" {
+			script := src + "/" + name + ".sh"
+			err = os.WriteFile(script, []byte(patch.Script), 0755)
+			if err != nil {
+				return
+			}
+			_, err = sh(src, script)
+			if err != nil {
+				return
+			}
+		}
+	}
+	return
+}
+
 func build(tmp string, ka config.Artifact, ki config.KernelInfo,
 	dockerTimeout time.Duration) (outPath, output string, err error) {
 
@@ -169,6 +222,11 @@ func build(tmp string, ka config.Artifact, ki config.KernelInfo,
 		return
 	}
 
+	err = applyPatches(tmpSourcePath, ka)
+	if err != nil {
+		return
+	}
+
 	outPath = tmpSourcePath + "/" + target
 	if ka.Type == config.KernelModule {
 		outPath += ".ko"