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_test.go

@@ -1,8 +1,11 @@
 package server
 
 import (
+	"io/fs"
 	"net/http"
 	"net/url"
+	"os"
+	"path/filepath"
 
 	"github.com/navidrome/navidrome/conf"
 	. "github.com/onsi/ginkgo/v2"
@@ -58,3 +61,49 @@ var _ = Describe("AbsoluteURL", func() {
 		})
 	})
 })
+
+var _ = Describe("createUnixSocketFile", func() {
+	var socketPath string
+
+	BeforeEach(func() {
+		tempDir, _ := os.MkdirTemp("", "create_unix_socket_file_test")
+		socketPath = filepath.Join(tempDir, "test.sock")
+		DeferCleanup(func() {
+			_ = os.RemoveAll(tempDir)
+		})
+	})
+
+	When("unixSocketPerm is valid", func() {
+		It("updates the permission of the unix socket file and returns nil", func() {
+			_, err := createUnixSocketFile(socketPath, "0777")
+			fileInfo, _ := os.Stat(socketPath)
+			actualPermission := fileInfo.Mode().Perm()
+
+			Expect(actualPermission).To(Equal(os.FileMode(0777)))
+			Expect(err).ToNot(HaveOccurred())
+
+		})
+	})
+
+	When("unixSocketPerm is invalid", func() {
+		It("returns an error", func() {
+			_, err := createUnixSocketFile(socketPath, "invalid")
+			Expect(err).To(HaveOccurred())
+
+		})
+	})
+
+	When("file already exists", func() {
+		It("recreates the file as a socket with the right permissions", func() {
+			_, err := os.Create(socketPath)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(os.Chmod(socketPath, os.FileMode(0777))).To(Succeed())
+
+			_, err = createUnixSocketFile(socketPath, "0600")
+			Expect(err).ToNot(HaveOccurred())
+			fileInfo, _ := os.Stat(socketPath)
+			Expect(fileInfo.Mode().Perm()).To(Equal(os.FileMode(0600)))
+			Expect(fileInfo.Mode().Type()).To(Equal(fs.ModeSocket))
+		})
+	})
+})