def do_create_v8_qemu_wrapper(d):
    """Creates a small wrapper that invokes QEMU to run some target V8 binaries
    on the host."""
    qemu_libdirs = [d.expand('${STAGING_DIR_HOST}${libdir}'),
                    d.expand('${STAGING_DIR_HOST}${base_libdir}')]
    qemu_cmd = qemu_wrapper_cmdline(d, d.getVar('STAGING_DIR_HOST'),
                                    qemu_libdirs)

    if d.getVar("HOST_AND_TARGET_SAME_WIDTH") == "1":
        qemu_cmd = ""

    wrapper_path = d.expand('${B}/v8-qemu-wrapper.sh')
    with open(wrapper_path, 'w') as wrapper_file:
        wrapper_file.write("""#!/bin/sh

# This file has been generated automatically.
# It invokes QEMU to run binaries built for the target in the host during the
# build process.

%s "$@"
""" % qemu_cmd)
    os.chmod(wrapper_path, 0o755)

do_create_v8_qemu_wrapper(d)

def qemu_wrapper_cmdline(data, rootfs_path, library_paths):
    import string

    qemu_binary = qemu_target_binary(data)
    if qemu_binary == "qemu-allarch":
        qemu_binary = "qemuwrapper"

    qemu_options = data.getVar("QEMU_OPTIONS") or ""

    return "PSEUDO_UNLOAD=1 " + qemu_binary + " " + qemu_options + " -L " + rootfs_path\
            + " -E LD_LIBRARY_PATH=" + ":".join(library_paths) + " "

# Next function will return a string containing the command that is needed to
# to run a certain binary through qemu. For example, in order to make a certain
# postinstall scriptlet run at do_rootfs time and running the postinstall is
# architecture dependent, we can run it through qemu. For example, in the
# postinstall scriptlet, we could use the following:
#
# ${@qemu_run_binary(d, '$D', '/usr/bin/test_app')} [test_app arguments]
#

def qemu_target_binary(data):
    package_arch = data.getVar("PACKAGE_ARCH")
    qemu_target_binary = (data.getVar("QEMU_TARGET_BINARY_%s" % package_arch) or "")
    if qemu_target_binary:
        return qemu_target_binary

    target_arch = data.getVar("TARGET_ARCH")
    if target_arch in ("i486", "i586", "i686"):
        target_arch = "i386"
    elif target_arch == "powerpc":
        target_arch = "ppc"
    elif target_arch == "powerpc64":
        target_arch = "ppc64"
    elif target_arch == "powerpc64le":
        target_arch = "ppc64le"

    return "qemu-" + target_arch