librechroot: give a good error message if binfmt_misc isn't configured

1 files changed, 10 insertions, 1 deletions

diff --git a/src/chroot-tools/librechroot b/src/chroot-tools/librechroot
index cc416d5..e671814 100755
--- a/src/chroot-tools/librechroot
+++ b/src/chroot-tools/librechroot
@@ -71,7 +71,16 @@ hack_arch_nspawn_flags() {
 	fi
 
 	if [[ "$CARCH" == armv7h ]] && ! setarch armv7l 2>/dev/null; then
-		arch_nspawn_flags+=(-f /usr/bin/qemu-arm-static -s)
+		if grep -xF 'enabled' /proc/sys/fs/binfmt_misc/arm &>/dev/null \
+	        && grep -xF 'interpreter /usr/bin/qemu-arm-static' /proc/sys/fs/binfmt_misc/arm &>/dev/null; then
+			arch_nspawn_flags+=(-f /usr/bin/qemu-arm-static -s)
+		else
+			error 'Cannot cross-compile for ARM on x86'
+			plain 'This requires a binfmt_misc entry for qemu-arm-static,'
+			plain 'which is provided by the %s package.' binfmt-qemu-static
+			plain 'If you have this, you may need to restart %s.' systemd-binfmt.service
+			return 1
+		fi
 	fi
 }