From e3520835bb0e896eda86132cad2ba9bc4ac4765f Mon Sep 17 00:00:00 2001
From: Ophestra <cat@gensokyo.uk>
Date: Fri, 8 May 2026 13:29:23 +0900
Subject: [PATCH] cmd/mbf: optionally register all targets

This enables non-native cures from the daemon.

Signed-off-by: Ophestra <cat@gensokyo.uk>
---
 cmd/mbf/cache.go        | 64 ++++++++++++++++-------------------------
 cmd/mbf/main.go         | 19 +++++++++++-
 internal/rosa/stage0.go |  9 ++++++
 3 files changed, 52 insertions(+), 40 deletions(-)

diff --git a/cmd/mbf/cache.go b/cmd/mbf/cache.go
index 9a7d2ce6..0452a3e1 100644
--- a/cmd/mbf/cache.go
+++ b/cmd/mbf/cache.go
@@ -4,13 +4,11 @@ import (
 	"context"
 	"os"
 	"path/filepath"
-	"runtime"
 	"testing"
 
 	"hakurei.app/check"
 	"hakurei.app/container"
 	"hakurei.app/internal/pkg"
-	"hakurei.app/internal/rosa"
 	"hakurei.app/message"
 )
 
@@ -22,10 +20,15 @@ type cache struct {
 	// Should generally not be used directly.
 	c *pkg.Cache
 
-	cures, jobs        int
-	hostAbstract, idle bool
-	verboseInit        bool
-	arch               string
+	cures, jobs int
+	// Primarily to work around missing landlock LSM.
+	hostAbstract bool
+	// Set SCHED_IDLE.
+	idle bool
+	// Unset [pkg.CSuppressInit].
+	verboseInit bool
+	// Loaded artifact of [rosa.QEMU].
+	qemu pkg.Artifact
 
 	base string
 }
@@ -83,49 +86,32 @@ func (cache *cache) open() (err error) {
 	}
 	done <- struct{}{}
 
-	if cache.arch != "" && cache.arch != runtime.GOARCH {
-		var (
-			name   string
-			offset byte
-			magic  string
-			mask   string
-		)
-		switch cache.arch {
-		case "riscv64":
-			name = "riscv64"
-			offset = 0
-			magic = "\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xf3\x00"
-			mask = "\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff"
-
-		case "arm64":
-			name = "aarch64"
-			offset = 0
-			magic = "\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xb7\x00"
-			mask = "\xff\xff\xff\xff\xff\xff\xff\xfc\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff"
-
-		default:
-			cache.c.Close()
-			err = pkg.UnsupportedArchError(cache.arch)
-			return
-		}
-
+	if cache.qemu != nil {
 		var pathname *check.Absolute
-		pathname, _, err = cache.c.Cure(rosa.Std.Load(rosa.QEMU))
+		pathname, _, err = cache.c.Cure(cache.qemu)
 		if err != nil {
 			cache.c.Close()
 			return
 		}
 
-		pkg.RegisterArch(cache.arch, container.BinfmtEntry{
-			Offset: offset,
-			Magic:  magic,
-			Mask:   mask,
+		pkg.RegisterArch("riscv64", container.BinfmtEntry{
+			Offset: 0,
+			Magic:  "\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xf3\x00",
+			Mask:   "\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff",
 			Interpreter: pathname.Append(
 				"system/bin",
-				"qemu-"+name,
+				"qemu-riscv64",
+			),
+		})
+		pkg.RegisterArch("arm64", container.BinfmtEntry{
+			Offset: 0,
+			Magic:  "\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xb7\x00",
+			Mask:   "\xff\xff\xff\xff\xff\xff\xff\xfc\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff",
+			Interpreter: pathname.Append(
+				"system/bin",
+				"qemu-aarch64",
 			),
 		})
-		rosa.DropCaches(cache.arch, rosa.Flags())
 	}
 
 	return
diff --git a/cmd/mbf/main.go b/cmd/mbf/main.go
index a5f1807a..e9cd8f4f 100644
--- a/cmd/mbf/main.go
+++ b/cmd/mbf/main.go
@@ -67,6 +67,8 @@ func main() {
 
 	var (
 		flagQuiet bool
+		flagQEMU  bool
+		flagArch  string
 		flagCheck bool
 		flagLTO   bool
 
@@ -94,6 +96,17 @@ func main() {
 			flags |= rosa.OptLLVMNoLTO
 		}
 		rosa.DropCaches("", flags)
+		cross := flagArch != "" && flagArch != runtime.GOARCH
+		if flagQEMU || cross {
+			cm.qemu = rosa.Std.Load(rosa.QEMU)
+		}
+
+		if cross {
+			rosa.DropCaches(flagArch, rosa.Flags())
+			if !rosa.HasStage0() {
+				return pkg.UnsupportedArchError(flagArch)
+			}
+		}
 
 		return nil
 	}).Flag(
@@ -101,7 +114,11 @@ func main() {
 		"q", command.BoolFlag(false),
 		"Do not print cure messages",
 	).Flag(
-		&cm.arch,
+		&flagQEMU,
+		"register", command.BoolFlag(false),
+		"Enable additional target architectures",
+	).Flag(
+		&flagArch,
 		"arch", command.StringFlag(runtime.GOARCH),
 		"Target architecture",
 	).Flag(
diff --git a/internal/rosa/stage0.go b/internal/rosa/stage0.go
index 1862e47a..65274885 100644
--- a/internal/rosa/stage0.go
+++ b/internal/rosa/stage0.go
@@ -49,3 +49,12 @@ func init() {
 		Description: "Rosa OS stage0 bootstrap seed",
 	}
 }
+
+// HasStage0 returns whether a stage0 distribution is available.
+func HasStage0() (ok bool) {
+	func() {
+		defer func() { ok = recover() == nil }()
+		toolchainStage0.Load(stage0Dist)
+	}()
+	return
+}