internal/outcome: rename from app

This is less ambiguous, and more accurately describes the purpose of the package.

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

internal/outcome/finalise.go

@@ -0,0 +1,85 @@
+package outcome
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"os"
+	"os/user"
+	"sync/atomic"
+
+	"hakurei.app/hst"
+	"hakurei.app/message"
+	"hakurei.app/system"
+)
+
+func newWithMessage(msg string) error { return newWithMessageError(msg, os.ErrInvalid) }
+func newWithMessageError(msg string, err error) error {
+	return &hst.AppError{Step: "finalise", Err: err, Msg: msg}
+}
+
+// An outcome is the runnable state of a hakurei container via [hst.Config].
+type outcome struct {
+	// Supplementary group ids. Populated during finalise.
+	supp []string
+	// Resolved priv side operating system interactions. Populated during finalise.
+	sys *system.I
+	// Transmitted to shim. Populated during finalise.
+	state *outcomeState
+	// Kept for saving to [state].
+	config *hst.Config
+
+	// Whether the current process is in outcome.main.
+	active atomic.Bool
+
+	ctx context.Context
+	syscallDispatcher
+}
+
+func (k *outcome) finalise(ctx context.Context, msg message.Msg, id *hst.ID, config *hst.Config) error {
+	if ctx == nil || id == nil {
+		// unreachable
+		panic("invalid call to finalise")
+	}
+	if k.ctx != nil || k.sys != nil || k.state != nil {
+		// unreachable
+		panic("attempting to finalise twice")
+	}
+	k.ctx = ctx
+
+	if err := config.Validate(); err != nil {
+		return err
+	}
+
+	// hsu expects numerical group ids
+	supp := make([]string, len(config.Groups))
+	for i, name := range config.Groups {
+		if gid, err := k.lookupGroupId(name); err != nil {
+			var unknownGroupError user.UnknownGroupError
+			if errors.As(err, &unknownGroupError) {
+				return newWithMessageError(fmt.Sprintf("unknown group %q", name), unknownGroupError)
+			} else {
+				return &hst.AppError{Step: "look up group by name", Err: err}
+			}
+		} else {
+			supp[i] = gid
+		}
+	}
+
+	// early validation complete at this point
+	s := newOutcomeState(k.syscallDispatcher, msg, id, config, &Hsu{k: k})
+	if err := s.populateLocal(k.syscallDispatcher, msg); err != nil {
+		return err
+	}
+
+	sys := system.New(k.ctx, msg, s.uid.unwrap())
+	if err := s.newSys(config, sys).toSystem(); err != nil {
+		return err
+	}
+
+	k.sys = sys
+	k.supp = supp
+	k.state = s
+	k.config = config
+	return nil
+}