2

README.md

@@ -19,6 +19,8 @@ go build -o samba-configer .
 The program:
 
 - Reads the Samba config and parses non-`[global]` sections as shares.
+- Detects a missing Samba installation when the config file does not exist yet.
+- Offers to install the Samba server package with a detected package manager such as `apt`, `dnf`, `yum`, `pacman`, `zypper`, or `apk`.
 - Prompts to add, edit, or delete a share.
 - Checks `valid users` entries against local accounts.
 - Offers to create missing local accounts with `useradd -M -s /usr/sbin/nologin <user>`.

app.go

@@ -24,6 +24,8 @@ type CommandRunner interface {
 	Run(name string, args ...string) error
 }
 
+type LookPathFunc func(file string) (string, error)
+
 type RealUserManager struct{}
 
 func (RealUserManager) UserExists(name string) bool {
@@ -49,14 +51,18 @@ func (OSCommandRunner) Run(name string, args ...string) error {
 type App struct {
 	configPath string
 	users      UserManager
+	runner     CommandRunner
+	lookPath   LookPathFunc
 	reader     *bufio.Reader
 	writer     *bufio.Writer
 }
 
-func NewApp(configPath string, users UserManager) *App {
+func NewApp(configPath string, users UserManager, runner CommandRunner, lookPath LookPathFunc) *App {
 	return &App{
 		configPath: configPath,
 		users:      users,
+		runner:     runner,
+		lookPath:   lookPath,
 		reader:     bufio.NewReader(os.Stdin),
 		writer:     bufio.NewWriter(os.Stdout),
 	}
@@ -65,9 +71,17 @@ func NewApp(configPath string, users UserManager) *App {
 func (a *App) Run() error {
 	doc, err := ParseConfigFile(a.configPath)
 	if err != nil {
+		if os.IsNotExist(err) {
+			doc, err = a.handleMissingConfig()
+			if err == nil {
+				goto loaded
+			}
+		}
+
 		return fmt.Errorf("read config: %w", err)
 	}
 
+loaded:
 	for {
 		shareSections := doc.ShareSections()
 		a.println("")
@@ -118,6 +132,47 @@ func (a *App) Run() error {
 	}
 }
 
+func (a *App) handleMissingConfig() (*Document, error) {
+	a.println("")
+	a.println("Samba is not set up yet on this computer.")
+	a.printf("I couldn't find the Samba config file at %s.\n", a.configPath)
+
+	plan, ok := DetectSambaInstallPlan(a.lookPath, os.Geteuid() == 0)
+	if !ok {
+		a.println("I also couldn't find a supported package manager automatically.")
+		a.println("Install the Samba server package for your Linux distribution, then run this tool again.")
+		a.flush()
+		return nil, os.ErrNotExist
+	}
+
+	a.println("")
+	a.printf("I found %s and can try to install the Samba server for you.\n", plan.ManagerName)
+	a.printf("This would run: %s\n", plan.DisplayCommand())
+	a.println("You may be asked for your administrator password.")
+	a.flush()
+
+	install, err := a.confirm("Install Samba server now", true)
+	if err != nil {
+		return nil, err
+	}
+	if !install {
+		return nil, os.ErrNotExist
+	}
+
+	if err := a.runner.Run(plan.Command[0], plan.Command[1:]...); err != nil {
+		return nil, fmt.Errorf("install Samba with %s: %w", plan.ManagerName, err)
+	}
+
+	doc, err := ParseConfigFile(a.configPath)
+	if err != nil {
+		return nil, fmt.Errorf("Samba installation finished, but the config file is still missing at %s: %w", a.configPath, err)
+	}
+
+	a.println("Samba was installed and the config file is now available.")
+	a.flush()
+	return doc, nil
+}
+
 func (a *App) addShare(doc *Document) error {
 	cfg, err := a.collectShareConfig(ShareConfig{})
 	if err != nil {

install.go

@@ -0,0 +1,63 @@
+package main
+
+import (
+	"os/exec"
+	"strings"
+)
+
+type InstallPlan struct {
+	ManagerName string
+	Command     []string
+}
+
+func (p InstallPlan) DisplayCommand() string {
+	return strings.Join(p.Command, " ")
+}
+
+func execLookPath(file string) (string, error) {
+	return exec.LookPath(file)
+}
+
+func DetectSambaInstallPlan(lookPath LookPathFunc, isRoot bool) (InstallPlan, bool) {
+	sudoPrefix := []string{}
+	if !isRoot {
+		if _, err := lookPath("sudo"); err == nil {
+			sudoPrefix = []string{"sudo"}
+		}
+	}
+
+	plans := []struct {
+		bin     string
+		name    string
+		command []string
+	}{
+		{bin: "apt-get", name: "apt", command: []string{"apt-get", "update"}},
+		{bin: "apt-get", name: "apt", command: []string{"apt-get", "install", "-y", "samba"}},
+		{bin: "dnf", name: "dnf", command: []string{"dnf", "install", "-y", "samba"}},
+		{bin: "yum", name: "yum", command: []string{"yum", "install", "-y", "samba"}},
+		{bin: "pacman", name: "pacman", command: []string{"pacman", "-Sy", "--noconfirm", "samba"}},
+		{bin: "zypper", name: "zypper", command: []string{"zypper", "--non-interactive", "install", "samba"}},
+		{bin: "apk", name: "apk", command: []string{"apk", "add", "samba"}},
+	}
+
+	if _, err := lookPath("apt-get"); err == nil {
+		return InstallPlan{
+			ManagerName: "apt",
+			Command: append(
+				append([]string{}, sudoPrefix...),
+				"sh", "-c", "apt-get update && apt-get install -y samba",
+			),
+		}, true
+	}
+
+	for _, plan := range plans[2:] {
+		if _, err := lookPath(plan.bin); err == nil {
+			return InstallPlan{
+				ManagerName: plan.name,
+				Command:     append(append([]string{}, sudoPrefix...), plan.command...),
+			}, true
+		}
+	}
+
+	return InstallPlan{}, false
+}

main.go

@@ -11,7 +11,7 @@ func main() {
 	configPath := flag.String("config", "/etc/samba/smb.conf", "path to smb.conf")
 	flag.Parse()
 
-	app := NewApp(*configPath, RealUserManager{})
+	app := NewApp(*configPath, RealUserManager{}, OSCommandRunner{}, execLookPath)
 	if err := app.Run(); err != nil {
 		if errors.Is(err, ErrCancelled) {
 			fmt.Fprintln(os.Stderr, "cancelled")

parser_test.go

@@ -94,3 +94,50 @@ func TestSerializeProducesSectionHeaders(t *testing.T) {
 		}
 	}
 }
+
+func TestDetectSambaInstallPlanPrefersApt(t *testing.T) {
+	lookPath := func(file string) (string, error) {
+		switch file {
+		case "apt-get", "sudo":
+			return "/usr/bin/" + file, nil
+		default:
+			return "", execErr(file)
+		}
+	}
+
+	plan, ok := DetectSambaInstallPlan(lookPath, false)
+	if !ok {
+		t.Fatalf("expected install plan")
+	}
+	if plan.ManagerName != "apt" {
+		t.Fatalf("expected apt manager, got %q", plan.ManagerName)
+	}
+	if plan.DisplayCommand() != "sudo sh -c apt-get update && apt-get install -y samba" {
+		t.Fatalf("unexpected command: %q", plan.DisplayCommand())
+	}
+}
+
+func TestDetectSambaInstallPlanWithoutSudo(t *testing.T) {
+	lookPath := func(file string) (string, error) {
+		switch file {
+		case "pacman":
+			return "/usr/bin/pacman", nil
+		default:
+			return "", execErr(file)
+		}
+	}
+
+	plan, ok := DetectSambaInstallPlan(lookPath, false)
+	if !ok {
+		t.Fatalf("expected install plan")
+	}
+	if plan.DisplayCommand() != "pacman -Sy --noconfirm samba" {
+		t.Fatalf("unexpected command: %q", plan.DisplayCommand())
+	}
+}
+
+type execErr string
+
+func (e execErr) Error() string {
+	return "not found: " + string(e)
+}