Anticipate arch-test not being installed and only check if chroot architecture is unequal host's architecture

mmdebstrap

@@ -954,37 +954,55 @@ sub main() {
     $options->{nativearch} = $nativearch;
     $options->{foreignarchs} = \@foreignarchs;
 
-    my $deb2qemu = {
+    {
-	alpha => 'alpha',
+	my $deb2qemu = {
-	amd64 => 'x86_64',
+	    alpha => 'alpha',
-	arm => 'arm',
+	    amd64 => 'x86_64',
-	arm64 => 'aarch64',
+	    arm => 'arm',
-	armel => 'arm',
+	    arm64 => 'aarch64',
-	armhf => 'arm',
+	    armel => 'arm',
-	hppa => 'hppa',
+	    armhf => 'arm',
-	i386 => 'i386',
+	    hppa => 'hppa',
-	m68k => 'm68k',
+	    i386 => 'i386',
-	mips => 'mips',
+	    m68k => 'm68k',
-	mips64 => 'mips64',
+	    mips => 'mips',
-	mips64el => 'mips64el',
+	    mips64 => 'mips64',
-	mipsel => 'mipsel',
+	    mips64el => 'mips64el',
-	powerpc => 'ppc',
+	    mipsel => 'mipsel',
-	ppc64 => 'ppc64',
+	    powerpc => 'ppc',
-	ppc64el => 'ppc64le',
+	    ppc64 => 'ppc64',
-	riscv64 => 'riscv64',
+	    ppc64el => 'ppc64le',
-	s390x => 's390x',
+	    riscv64 => 'riscv64',
-	sh4 => 'sh4',
+	    s390x => 's390x',
-	sparc => 'sparc',
+	    sh4 => 'sh4',
-	sparc64 => 'sparc64',
+	    sparc => 'sparc',
-    };
+	    sparc64 => 'sparc64',
-    open my $fh, '-|', 'arch-test', '-n', $nativearch // die "failed to fork(): $!";
+	};
-    chomp (my $content = do { local $/; <$fh> });
+	chomp (my $hostarch = `dpkg --print-architecture`);
-    close $fh;
+	if ($hostarch ne $nativearch) {
-    if ($? != 0 or $content ne "$nativearch: ok") {
+	    my $pid = open my $fh, '-|' // die "failed to fork(): $!";
-	if (!exists $deb2qemu->{$nativearch}) {
+	    if ($pid == 0) {
-	    die "no mapping from $nativearch to qemu-user binary";
+		{ exec 'arch-test', '-n', $nativearch; }
+		# if exec didn't work (for example because the arch-test program is
+		# missing) prepare for the worst and assume that the architecture
+		# cannot be executed
+		print "$nativearch: not supported on this machine/kernel\n";
+		exit 1;
+	    }
+	    chomp (my $content = do { local $/; <$fh> });
+	    close $fh;
+	    if ($? != 0 or $content ne "$nativearch: ok") {
+		print STDERR "I: $nativearch cannot be executed, falling back to qemu-user\n";
+		if (!exists $deb2qemu->{$nativearch}) {
+		    die "no mapping from $nativearch to qemu-user binary";
+		}
+		$options->{qemu} = $deb2qemu->{$nativearch};
+	    } else {
+		print STDERR "I: $nativearch can be executed on this $hostarch machine\n";
+	    }
+	} else {
+	    print STDERR "I: chroot architecture $nativearch is equal to the host's architecture\n";
 	}
-	$options->{qemu} = $deb2qemu->{$nativearch};
     }
 
     if (scalar @ARGV > 0) {