fix: Listening on abstract domain sockets (#7020)

When passed a socket name that starts with @, go will listen on an
abstract unix domain socket. Forgejo breaks this by assuming the socket
name is a file path and normalizing it to an absolute path.

This small commit prevents treating the socket name as a filesystem path
if it starts with @.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7020
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: Mewp <codeberg.org@mewp.pl>
Co-committed-by: Mewp <codeberg.org@mewp.pl>

modules/setting/server_test.go

@@ -73,3 +73,16 @@ MAX_USER_REDIRECTS = 8`
 	assert.EqualValues(t, 3, Service.UsernameCooldownPeriod)
 	assert.EqualValues(t, 8, Service.MaxUserRedirects)
 }
+
+func TestUnixSocketAbstractNamespace(t *testing.T) {
+	iniStr := `
+	[server]
+	PROTOCOL=http+unix
+	HTTP_ADDR=@forgejo
+	`
+	cfg, err := NewConfigProviderFromData(iniStr)
+	require.NoError(t, err)
+	loadServerFrom(cfg)
+
+	assert.EqualValues(t, "@forgejo", HTTPAddr)
+}