Improve Git config

internal/git/config.go

@@ -1,15 +1,24 @@
 package git
 
-import "os/exec"
+import (
+	"errors"
+	"os/exec"
+	"regexp"
+)
+
+type configEntry struct {
+	value string
+	fn    func(string, string) error
+}
 
 func InitGitConfig() error {
-	configs := map[string]string{
-		"receive.advertisePushOptions": "true",
-		"safe.directory":               "*",
+	configs := map[string]configEntry{
+		"receive.advertisePushOptions": {value: "true", fn: setGitConfig},
+		"safe.directory":               {value: "*", fn: addGitConfig},
 	}
 
-	for key, value := range configs {
-		if err := setGitConfig(key, value); err != nil {
+	for key, entry := range configs {
+		if err := entry.fn(key, entry.value); err != nil {
 			return err
 		}
 	}
@@ -18,6 +27,37 @@ func InitGitConfig() error {
 }
 
 func setGitConfig(key, value string) error {
+	_, err := getGitConfig(key, value)
+	if err != nil && !checkErrorCode(err, 1) {
+		return err
+	}
+
 	cmd := exec.Command("git", "config", "--global", key, value)
 	return cmd.Run()
 }
+
+func addGitConfig(key, value string) error {
+	_, err := getGitConfig(key, regexp.QuoteMeta(value))
+	if err == nil {
+		return nil
+	}
+	if checkErrorCode(err, 1) {
+		cmd := exec.Command("git", "config", "--global", "--add", key, value)
+		return cmd.Run()
+	}
+	return err
+}
+
+func getGitConfig(key, value string) (string, error) {
+	cmd := exec.Command("git", "config", "--global", "--get", key, value)
+	out, err := cmd.Output()
+	return string(out), err
+}
+
+func checkErrorCode(err error, code int) bool {
+	var exitError *exec.ExitError
+	if errors.As(err, &exitError) {
+		return exitError.ExitCode() == code
+	}
+	return false
+}