container: remove setup pipe helper

The API forces use of finalizer to close the read end of the setup pipe, which is no longer considered acceptable. Exporting this as part of package container also imposes unnecessary maintenance burden.

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

internal/outcome/process.go

@@ -13,7 +13,6 @@ import (
 	"time"
 
 	"hakurei.app/check"
-	"hakurei.app/container"
 	"hakurei.app/fhs"
 	"hakurei.app/hst"
 	"hakurei.app/internal/info"
@@ -372,17 +371,18 @@ func (k *outcome) start(ctx context.Context, msg message.Msg,
 	// shim runs in the same session as monitor; see shim.go for behaviour
 	cmd.Cancel = func() error { return cmd.Process.Signal(syscall.SIGCONT) }
 
-	var shimPipe *os.File
-	if fd, w, err := container.Setup(&cmd.ExtraFiles); err != nil {
+	var shimPipe [2]*os.File
+	if r, w, err := os.Pipe(); err != nil {
 		return cmd, nil, &hst.AppError{Step: "create shim setup pipe", Err: err}
 	} else {
-		shimPipe = w
 		cmd.Env = []string{
 			// passed through to shim by hsu
-			shimEnv + "=" + strconv.Itoa(fd),
+			shimEnv + "=" + strconv.Itoa(3+len(cmd.ExtraFiles)),
 			// interpreted by hsu
 			"HAKUREI_IDENTITY=" + k.state.identity.String(),
 		}
+		cmd.ExtraFiles = append(cmd.ExtraFiles, r)
+		shimPipe[0], shimPipe[1] = r, w
 	}
 
 	if len(k.supp) > 0 {
@@ -393,12 +393,16 @@ func (k *outcome) start(ctx context.Context, msg message.Msg,
 
 	msg.Verbosef("setuid helper at %s", hsuPath)
 	if err := cmd.Start(); err != nil {
+		_, _ = shimPipe[0].Close(), shimPipe[1].Close()
 		msg.Resume()
-		return cmd, shimPipe, &hst.AppError{Step: "start setuid wrapper", Err: err}
+		return cmd, nil, &hst.AppError{Step: "start setuid wrapper", Err: err}
+	}
+	if err := shimPipe[0].Close(); err != nil {
+		msg.Verbose(err)
 	}
 
 	*startTime = time.Now().UTC()
-	return cmd, shimPipe, nil
+	return cmd, shimPipe[1], nil
 }
 
 // serveShim serves outcomeState through the shim setup pipe.
@@ -411,11 +415,11 @@ func serveShim(msg message.Msg, shimPipe *os.File, state *outcomeState) error {
 		msg.Verbose(err.Error())
 	}
 	if err := gob.NewEncoder(shimPipe).Encode(state); err != nil {
+		_ = shimPipe.Close()
 		msg.Resume()
 		return &hst.AppError{Step: "transmit shim config", Err: err}
 	}
-	_ = shimPipe.Close()
-	return nil
+	return shimPipe.Close()
 }
 
 // printMessageError prints the error message according to [message.GetMessage],