shim: new shim implementation

This implementation of shim accepts configuration as a gob stream over a unix socket, with support for mediating access to wayland via WAYLAND_SOCKET fd. All configuration is now included in the payload, and child is started inside bwrap configured with supplied bwrap.Config.

Signed-off-by: Ophestra Umiker <cat@ophivana.moe>

internal/shim/payload.go

@@ -0,0 +1,23 @@
+package shim
+
+import (
+	"git.ophivana.moe/cat/fortify/helper/bwrap"
+)
+
+const EnvShim = "FORTIFY_SHIM"
+
+type Payload struct {
+	// child full argv
+	Argv []string
+	// env variables passed through to bwrap
+	Env []string
+	// bwrap, target full exec path
+	Exec [2]string
+	// bwrap config, nil for permissive
+	Bwrap *bwrap.Config
+	// whether to pas wayland fd
+	WL bool
+
+	// verbosity pass through
+	Verbose bool
+}