Make tool request elevated privileges on-demand

pkg/auth/auth.go

@@ -0,0 +1,104 @@
+package auth
+
+import (
+	"fmt"
+	"os/exec"
+	"regexp"
+	"strconv"
+	"time"
+
+	"github.com/Riyyi/declpac/pkg/log"
+)
+
+var tool string
+var timeout time.Duration = 5 * time.Minute
+var refreshCommand []string = []string{"-n", "true"}
+
+// -----------------------------------------
+// public
+
+func Command(name string, args ...string) *exec.Cmd {
+	if tool == "" {
+		return log.Command(name, args...)
+	}
+	args = append([]string{name}, args...)
+	return log.Command(tool, args...)
+}
+
+func Run() {
+	exec.Command(tool, refreshCommand...).Run()
+}
+
+func Start() error {
+	err := detect()
+	if err != nil {
+		return err
+	}
+
+	// Automatically refresh privilege elevation to prevent user prompts
+	go func() {
+		for {
+			Run()
+			time.Sleep(timeout)
+		}
+	}()
+
+	return nil
+}
+
+// -----------------------------------------
+// private
+
+func detect() error {
+	tool = getTool()
+	if tool == "" {
+		return fmt.Errorf("no privilege elevation tool detected in PATH")
+	}
+
+	parseTimeout()
+	// We have to be a little faster than the actual timeout
+	timeout -= 30 * time.Second
+
+	return nil
+}
+
+func execLookPath(name string) string {
+	path, err := exec.LookPath(name)
+	if err != nil {
+		return ""
+	}
+	return path
+}
+
+func getTool() string {
+	sudo := execLookPath("sudo")
+	doas := execLookPath("doas")
+
+	if sudo != "" {
+		return "sudo"
+	}
+	if doas != "" {
+		return "doas"
+	}
+
+	return ""
+}
+
+func parseTimeout() {
+	switch tool {
+	case "sudo":
+		out, err := exec.Command("sudo", "sudo", "-V").CombinedOutput()
+		if err != nil {
+			return
+		}
+		re := regexp.MustCompile(`Authentication timestamp timeout: (\d+)\..*`)
+		matches := re.FindStringSubmatch(string(out))
+		if len(matches) == 2 {
+			if minutes, err := strconv.Atoi(matches[1]); err == nil {
+				timeout = time.Duration(minutes) * time.Minute
+			}
+		}
+	case "doas":
+		exec.Command("doas", "true").Run()
+	}
+}