1 files changed, 159 insertions, 0 deletions
diff --git a/internal/system/dbus.go b/internal/system/dbus.go
new file mode 100644
index 00000000..3e4a6e65
--- /dev/null
+++ b/internal/system/dbus.go
@@ -0,0 +1,159 @@
+package system
+
+import (
+	"errors"
+	"fmt"
+	"os"
+
+	"git.ophivana.moe/cat/fortify/dbus"
+	"git.ophivana.moe/cat/fortify/internal/fmsg"
+	"git.ophivana.moe/cat/fortify/internal/state"
+	"git.ophivana.moe/cat/fortify/internal/verbose"
+)
+
+var (
+	ErrDBusConfig = errors.New("dbus config not supplied")
+)
+
+func (sys *I) ProxyDBus(session, system *dbus.Config, sessionPath, systemPath string) error {
+	d := new(DBus)
+
+	// used by waiting goroutine to notify process exit
+	d.done = make(chan struct{})
+
+	// session bus is mandatory
+	if session == nil {
+		return fmsg.WrapError(ErrDBusConfig,
+			"attempted to seal message bus proxy without session bus config")
+	}
+
+	// system bus is optional
+	d.system = system == nil
+
+	// upstream address, downstream socket path
+	var sessionBus, systemBus [2]string
+
+	// resolve upstream bus addresses
+	sessionBus[0], systemBus[0] = dbus.Address()
+
+	// set paths from caller
+	sessionBus[1], systemBus[1] = sessionPath, systemPath
+
+	// create proxy instance
+	d.proxy = dbus.New(sessionBus, systemBus)
+
+	defer func() {
+		if verbose.Get() && d.proxy.Sealed() {
+			verbose.Println("sealed session proxy", session.Args(sessionBus))
+			if system != nil {
+				verbose.Println("sealed system proxy", system.Args(systemBus))
+			}
+			verbose.Println("message bus proxy final args:", d.proxy)
+		}
+	}()
+
+	// queue operation
+	sys.ops = append(sys.ops, d)
+
+	// seal dbus proxy
+	return fmsg.WrapErrorSuffix(d.proxy.Seal(session, system),
+		"cannot seal message bus proxy:")
+}
+
+type DBus struct {
+	proxy *dbus.Proxy
+
+	// whether system bus proxy is enabled
+	system bool
+	// notification from goroutine waiting for dbus.Proxy
+	done chan struct{}
+}
+
+func (d *DBus) Type() state.Enablement {
+	return Process
+}
+
+func (d *DBus) apply(_ *I) error {
+	verbose.Printf("session bus proxy on %q for upstream %q\n", d.proxy.Session()[1], d.proxy.Session()[0])
+	if d.system {
+		verbose.Printf("system bus proxy on %q for upstream %q\n", d.proxy.System()[1], d.proxy.System()[0])
+	}
+
+	// ready channel passed to dbus package
+	ready := make(chan error, 1)
+
+	// background dbus proxy start
+	if err := d.proxy.Start(ready, os.Stderr, true); err != nil {
+		return fmsg.WrapErrorSuffix(err,
+			"cannot start message bus proxy:")
+	}
+	verbose.Println("starting message bus proxy:", d.proxy)
+	if verbose.Get() { // save the extra bwrap arg build when verbose logging is off
+		verbose.Println("message bus proxy bwrap args:", d.proxy.Bwrap())
+	}
+
+	// background wait for proxy instance and notify completion
+	go func() {
+		if err := d.proxy.Wait(); err != nil {
+			fmt.Println("fortify: message bus proxy exited with error:", err)
+			go func() { ready <- err }()
+		} else {
+			verbose.Println("message bus proxy exit")
+		}
+
+		// ensure socket removal so ephemeral directory is empty at revert
+		if err := os.Remove(d.proxy.Session()[1]); err != nil && !errors.Is(err, os.ErrNotExist) {
+			fmt.Println("fortify: cannot remove dangling session bus socket:", err)
+		}
+		if d.system {
+			if err := os.Remove(d.proxy.System()[1]); err != nil && !errors.Is(err, os.ErrNotExist) {
+				fmt.Println("fortify: cannot remove dangling system bus socket:", err)
+			}
+		}
+
+		// notify proxy completion
+		close(d.done)
+	}()
+
+	// ready is not nil if the proxy process faulted
+	if err := <-ready; err != nil {
+		// note that err here is either an I/O error or a predetermined unexpected behaviour error
+		return fmsg.WrapErrorSuffix(err,
+			"message bus proxy fault after start:")
+	}
+	verbose.Println("message bus proxy ready")
+
+	return nil
+}
+
+func (d *DBus) revert(_ *I, _ *Criteria) error {
+	// criteria ignored here since dbus is always process-scoped
+	verbose.Println("terminating message bus proxy")
+
+	if err := d.proxy.Close(); err != nil {
+		if errors.Is(err, os.ErrClosed) {
+			return fmsg.WrapError(err,
+				"message bus proxy already closed")
+		} else {
+			return fmsg.WrapErrorSuffix(err,
+				"cannot stop message bus proxy:")
+		}
+	}
+
+	// block until proxy wait returns
+	<-d.done
+	return nil
+}
+
+func (d *DBus) Is(o Op) bool {
+	d0, ok := o.(*DBus)
+	return ok && d0 != nil && *d == *d0
+}
+
+func (d *DBus) Path() string {
+	return "(dbus proxy)"
+}
+
+func (d *DBus) String() string {
+	return d.proxy.String()
+}