app/instance: wrap internal implementation

This reduces the scope of the fst package, which was growing questionably large.

Signed-off-by: Ophestra <cat@gensokyo.uk>

cmd/fpkg/main.go

@@ -13,7 +13,7 @@ import (
 	"git.gensokyo.uk/security/fortify/command"
 	"git.gensokyo.uk/security/fortify/fst"
 	"git.gensokyo.uk/security/fortify/internal"
-	"git.gensokyo.uk/security/fortify/internal/app/setuid"
+	"git.gensokyo.uk/security/fortify/internal/app/instance"
 	"git.gensokyo.uk/security/fortify/internal/fmsg"
 	"git.gensokyo.uk/security/fortify/internal/sys"
 	"git.gensokyo.uk/security/fortify/sandbox"
@@ -62,7 +62,7 @@ func main() {
 		Flag(&flagVerbose, "v", command.BoolFlag(false), "Print debug messages to the console").
 		Flag(&flagDropShell, "s", command.BoolFlag(false), "Drop to a shell in place of next fortify action")
 
-	c.Command("shim", command.UsageInternal, func([]string) error { setuid.ShimMain(); return errSuccess })
+	c.Command("shim", command.UsageInternal, func([]string) error { instance.ShimMain(); return errSuccess })
 
 	{
 		var (

cmd/fpkg/proc.go

@@ -5,20 +5,21 @@ import (
 	"os"
 
 	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/internal/app/setuid"
+	"git.gensokyo.uk/security/fortify/internal/app"
+	"git.gensokyo.uk/security/fortify/internal/app/instance"
 	"git.gensokyo.uk/security/fortify/internal/fmsg"
 )
 
 func mustRunApp(ctx context.Context, config *fst.Config, beforeFail func()) {
-	rs := new(fst.RunState)
-	a := setuid.MustNew(ctx, std)
+	rs := new(app.RunState)
+	a := instance.MustNew(instance.ISetuid, ctx, std)
 
 	var code int
 	if sa, err := a.Seal(config); err != nil {
 		fmsg.PrintBaseError(err, "cannot seal app:")
 		code = 1
 	} else {
-		code = setuid.PrintRunStateErr(rs, sa.Run(rs))
+		code = instance.PrintRunStateErr(instance.ISetuid, rs, sa.Run(rs))
 	}
 
 	if code != 0 {