diskimage-builder/diskimage_builder/elements/architecture-emulation-binaries/extra-data.d/01-copy-binary

#!/bin/bash

if [ ${DIB_DEBUG_TRACE:-1} -gt 0 ]; then
    set -x
fi
set -eu
set -o pipefail

function clean_up_arch_emulation {
    cat <<EOF >$TMP_MOUNT_PATH/tmp/clean_up_qemu_binary
#!/bin/bash

set -eux
set -o pipefail

sudo rm -rf "${TMP_MOUNT_PATH}${1}"
EOF

    sudo chmod +x "$TMP_MOUNT_PATH/tmp/clean_up_qemu_binary"
}

function check_copy_file {
    if [ -f "$1" ] ; then
        if [ ! -f "${TMP_MOUNT_PATH}${1}" ]; then
            sudo cp "$1" "$TMP_MOUNT_PATH/usr/bin"
            clean_up_arch_emulation $1
        fi
    else
        echo "qemu binary file not found."
        exit 1
    fi
}

function copy_binary {
    echo "checking for architecture compatibility..."
    img_arch=$2
    if [[ "$host_arch" != "$img_arch" ]]; then
        qemu_binary=$1
        check_copy_file $qemu_binary
    else
        echo "Emulation not required for this host/image architecture combination"
    fi
}

host_arch="$(uname -m)"

case "$ARCH" in
    "i386" | "amd64")
        qemu_binary_file="/usr/bin/qemu-i386-static"
        copy_binary $qemu_binary_file $ARCH
    ;;
    "armhf")
        qemu_binary_file="/usr/bin/qemu-arm-static"
        copy_binary $qemu_binary_file $ARCH
    ;;
    "arm64" | "aarch64")
        qemu_binary_file="/usr/bin/qemu-aarch64-static"
        copy_binary $qemu_binary_file $ARCH
    ;;
    *)
        echo "architecture not supported"
        exit 1
    ;;
esac