internal/rosa/busybox: cross-platform binary

The initial binary seed is arch-specific.

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

internal/rosa/busybox.go

@@ -5,6 +5,7 @@ import (
 	"io"
 	"net/http"
 	"os"
+	"runtime"
 	"slices"
 	"strings"
 	"time"
@@ -78,10 +79,23 @@ func (a busyboxBin) Cure(t *pkg.TContext) (err error) {
 // newBusyboxBin returns a [pkg.Artifact] containing a busybox installation from
 // the https://busybox.net/downloads/binaries/ binary release.
 func newBusyboxBin() pkg.Artifact {
-	const (
-		version  = "1.35.0"
+	var version, url, checksum string
+	switch runtime.GOARCH {
+	case "amd64":
+		version = "1.35.0"
+		url = "https://busybox.net/downloads/binaries/" +
+			version + "-" + linuxArch() + "-linux-musl/busybox"
 		checksum = "L7OBIsPu9enNHn7FqpBT1kOg_mCLNmetSeNMA3i4Y60Z5jTgnlX3qX3zcQtLx5AB"
-	)
+	case "arm64":
+		version = "1.31.0"
+		url = "https://busybox.net/downloads/binaries/" +
+			version + "-defconfig-multiarch-musl/busybox-armv8l"
+		checksum = "npJjBO7iwhjW6Kx2aXeSxf8kXhVgTCDChOZTTsI8ZfFfa3tbsklxRiidZQdrVERg"
+
+	default:
+		panic("unsupported target " + runtime.GOARCH)
+	}
+
 	return pkg.NewExec(
 		"busybox-bin-"+version, nil, pkg.ExecTimeoutMax, false,
 		fhs.AbsRoot, []string{
@@ -96,9 +110,7 @@ func newBusyboxBin() pkg.Artifact {
 			&http.Client{Transport: &http.Transport{
 				// busybox website is really slow to respond
 				TLSHandshakeTimeout: 2 * time.Minute,
-			}},
-			"https://busybox.net/downloads/binaries/"+
-				version+"-"+linuxArch()+"-linux-musl/busybox",
+			}}, url,
 			mustDecode(checksum),
 		)}),
 	)