Make server unix socket file permission configurable via flag UnixSocketPerm (#2763)

* feat(any): Add flag unixsocketperm with default 0017 - #2625

Signed-off-by: johannesengl <hello@johannesengl.com>

* feat(server): Update unix socket file perm based on config - #2625

Signed-off-by: johannesengl <hello@johannesengl.com>

* Fix default value of socket.

* Refactor unix socket file creation.

* Remove misplaced comment

---------

Signed-off-by: johannesengl <hello@johannesengl.com>
Co-authored-by: Caio Cotts <caio@cotts.com.br>
Co-authored-by: Deluan <deluan@navidrome.org>

server/server.go

@@ -9,6 +9,7 @@ import (
 	"net/url"
 	"os"
 	"path"
+	"strconv"
 	"strings"
 	"time"
 
@@ -71,13 +72,9 @@ func (s *Server) Run(ctx context.Context, addr string, port int, tlsCert string,
 	var err error
 	if strings.HasPrefix(addr, "unix:") {
 		socketPath := strings.TrimPrefix(addr, "unix:")
-		// Remove the socket file if it already exists
-		if err := os.Remove(socketPath); err != nil && !os.IsNotExist(err) {
-			return fmt.Errorf("error removing previous unix socket file: %w", err)
-		}
-		listener, err = net.Listen("unix", socketPath)
+		listener, err = createUnixSocketFile(socketPath, conf.Server.UnixSocketPerm)
 		if err != nil {
-			return fmt.Errorf("error creating unix socket listener: %w", err)
+			return err
 		}
 	} else {
 		addr = fmt.Sprintf("%s:%d", addr, port)
@@ -136,6 +133,28 @@ func (s *Server) Run(ctx context.Context, addr string, port int, tlsCert string,
 	return nil
 }
 
+func createUnixSocketFile(socketPath string, socketPerm string) (net.Listener, error) {
+	// Remove the socket file if it already exists
+	if err := os.Remove(socketPath); err != nil && !os.IsNotExist(err) {
+		return nil, fmt.Errorf("error removing previous unix socket file: %w", err)
+	}
+	// Create listener
+	listener, err := net.Listen("unix", socketPath)
+	if err != nil {
+		return nil, fmt.Errorf("error creating unix socket listener: %w", err)
+	}
+	// Converts the socketPerm to uint and updates the permission of the unix socket file
+	perm, err := strconv.ParseUint(socketPerm, 8, 32)
+	if err != nil {
+		return nil, fmt.Errorf("error parsing unix socket file permissions: %w", err)
+	}
+	err = os.Chmod(socketPath, os.FileMode(perm))
+	if err != nil {
+		return nil, fmt.Errorf("error updating permission of unix socket file: %w", err)
+	}
+	return listener, nil
+}
+
 func (s *Server) initRoutes() {
 	s.appRoot = path.Join(conf.Server.BasePath, consts.URLPathUI)