1 files changed, 69 insertions, 0 deletions
diff --git a/internal/dbus/dbus.go b/internal/dbus/dbus.go
new file mode 100644
index 00000000..9ea89f51
--- /dev/null
+++ b/internal/dbus/dbus.go
@@ -0,0 +1,69 @@
+// Package dbus wraps xdg-dbus-proxy and implements configuration and sandboxing of the underlying helper process.
+package dbus
+
+import (
+	"fmt"
+	"os"
+	"sync"
+)
+
+const (
+	/*
+		SessionBusAddress is the name of the environment variable where the address of the login session message bus is given in.
+
+		If that variable is not set, applications may also try to read the address from the X Window System root window property _DBUS_SESSION_BUS_ADDRESS.
+		The root window property must have type STRING. The environment variable should have precedence over the root window property.
+
+		The address of the login session message bus is given in the DBUS_SESSION_BUS_ADDRESS environment variable.
+		If DBUS_SESSION_BUS_ADDRESS is not set, or if it's set to the string "autolaunch:",
+		the system should use platform-specific methods of locating a running D-Bus session server,
+		or starting one if a running instance cannot be found.
+		Note that this mechanism is not recommended for attempting to determine if a daemon is running.
+		It is inherently racy to attempt to make this determination, since the bus daemon may be started just before or just after the determination is made.
+		Therefore, it is recommended that applications do not try to make this determination for their functionality purposes, and instead they should attempt to start the server.
+
+		This package diverges from the specification, as the caller is unlikely to be an X client, or be in a position to autolaunch a dbus server.
+		So a fallback address with a socket located in the well-known default XDG_RUNTIME_DIR formatting is used.
+	*/
+	SessionBusAddress = "DBUS_SESSION_BUS_ADDRESS"
+
+	/*
+		SystemBusAddress is the name of the environment variable where the address of the system message bus is given in.
+
+		If that variable is not set, applications should try to connect to the well-known address unix:path=/var/run/dbus/system_bus_socket.
+		Implementations of the well-known system bus should listen on an address that will result in that connection being successful.
+	*/
+	SystemBusAddress = "DBUS_SYSTEM_BUS_ADDRESS"
+
+	// FallbackSystemBusAddress is used when [SystemBusAddress] is not set.
+	FallbackSystemBusAddress = "unix:path=/var/run/dbus/system_bus_socket"
+)
+
+var (
+	address     [2]string
+	addressOnce sync.Once
+)
+
+// Address returns the session and system bus addresses copied from environment,
+// or appropriate fallback values if they are not set.
+func Address() (session, system string) {
+	addressOnce.Do(func() {
+		// resolve upstream session bus address
+		if addr, ok := os.LookupEnv(SessionBusAddress); !ok {
+			// fall back to default format
+			address[0] = fmt.Sprintf("unix:path=/run/user/%d/bus", os.Getuid())
+		} else {
+			address[0] = addr
+		}
+
+		// resolve upstream system bus address
+		if addr, ok := os.LookupEnv(SystemBusAddress); !ok {
+			// fall back to default hardcoded value
+			address[1] = FallbackSystemBusAddress
+		} else {
+			address[1] = addr
+		}
+	})
+
+	return address[0], address[1]
+}