internal/app: do not return from shim start

The whole RunState ugliness and the other horrendous error handling conditions for internal/app come from an old design proposal for maintaining all app containers under the same daemon process for a user. The proposal was ultimately rejected but the implementation remained. It is removed here to alleviate internal/app from much of its ugliness and unreadability.

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

internal/sys/hsu.go

@@ -3,6 +3,7 @@ package sys
 import (
 	"errors"
 	"fmt"
+	"log"
 	"os"
 	"os/exec"
 	"strconv"
@@ -11,6 +12,7 @@ import (
 	"hakurei.app/container"
 	"hakurei.app/hst"
 	"hakurei.app/internal"
+	"hakurei.app/internal/hlog"
 )
 
 // Hsu caches responses from cmd/hsu.
@@ -79,3 +81,24 @@ func (h *Hsu) Uid(identity int) (int, error) {
 	}
 	return u.uid, u.err
 }
+
+// MustUid calls [State.Uid] and terminates on error.
+func MustUid(s State, identity int) int {
+	uid, err := s.Uid(identity)
+	if err == nil {
+		return uid
+	}
+
+	const fallback = "cannot obtain uid from setuid wrapper:"
+	if errors.Is(err, ErrHsuAccess) {
+		hlog.Verbose("*"+fallback, err)
+		os.Exit(1)
+		return -0xdeadbeef
+	} else if m, ok := container.GetErrorMessage(err); ok {
+		log.Fatal(m)
+		return -0xdeadbeef
+	} else {
+		log.Fatalln(fallback, err)
+		return -0xdeadbeef
+	}
+}

internal/sys/interface.go

@@ -49,14 +49,8 @@ type State interface {
 	Uid(identity int) (int, error)
 }
 
-// GetUserID obtains user id from hsu by querying uid of identity 0.
-func GetUserID(os State) (int, error) {
-	if uid, err := os.Uid(0); err != nil {
-		return -1, err
-	} else {
-		return (uid / 10000) - 100, nil
-	}
-}
+// MustGetUserID obtains user id from hsu by querying uid of identity 0.
+func MustGetUserID(os State) int { return (MustUid(os, 0) / 10000) - 100 }
 
 // CopyPaths is a generic implementation of [hst.Paths].
 func CopyPaths(os State, v *hst.Paths, userid int) {

internal/sys/std.go

@@ -1,9 +1,7 @@
 package sys
 
 import (
-	"errors"
 	"io/fs"
-	"log"
 	"os"
 	"os/exec"
 	"os/user"
@@ -41,30 +39,6 @@ func (s *Std) Printf(format string, v ...any)               { hlog.Verbosef(form
 const xdgRuntimeDir = "XDG_RUNTIME_DIR"
 
 func (s *Std) Paths() hst.Paths {
-	s.pathsOnce.Do(func() {
-		if userid, err := GetUserID(s); err != nil {
-			// TODO(ophestra): this duplicates code in cmd/hakurei/command.go, keep this up to date until removal
-			hlog.BeforeExit()
-			const fallback = "cannot obtain user id from hsu:"
-
-			// this indicates the error message has already reached stderr, outside the current process's control;
-			// this is only reached when hsu fails for any reason, as a second error message following hsu is confusing
-			if errors.Is(err, ErrHsuAccess) {
-				hlog.Verbose("*"+fallback, err)
-				os.Exit(1)
-				return
-			}
-
-			m, ok := container.GetErrorMessage(err)
-			if !ok {
-				log.Fatalln(fallback, err)
-				return
-			}
-
-			log.Fatal(m)
-		} else {
-			CopyPaths(s, &s.paths, userid)
-		}
-	})
+	s.pathsOnce.Do(func() { CopyPaths(s, &s.paths, MustGetUserID(s)) })
 	return s.paths
 }