def ptest_update_alternatives(d):
    """
    This function will generate the symlinks in the PTEST_BINDIR_PKGD_PATH
    to match the renamed binaries by update-alternatives.
    """

    if not bb.data.inherits_class('update-alternatives', d) \
           or not update_alternatives_enabled(d):
        return

    bb.note("Generating symlinks for ptest")
    bin_paths = { d.getVar("bindir"), d.getVar("base_bindir"),
                   d.getVar("sbindir"), d.getVar("base_sbindir") }
    ptest_bindir = d.getVar("PTEST_BINDIR_PKGD_PATH")
    os.mkdir(ptest_bindir)
    for pkg in (d.getVar('PACKAGES') or "").split():
        alternatives = update_alternatives_alt_targets(d, pkg)
        for alt_name, alt_link, alt_target, _ in alternatives:
            # Some alternatives are for man pages,
            # check if the alternative is in PATH
            if os.path.dirname(alt_link) in bin_paths:
                os.symlink(alt_target, os.path.join(ptest_bindir, alt_name))

ptest_update_alternatives(d)

def update_alternatives_alt_targets(d, pkg):
    """
    Returns the update-alternatives metadata for a package.

    The returned format is a list of tuples where the tuple contains:
    alt_name:     The binary name
    alt_link:     The path for the binary (Shared by different packages)
    alt_target:   The path for the renamed binary (Unique per package)
    alt_priority: The priority of the alt_target

    All the alt_targets will be installed into the sysroot. The alt_link is
    a symlink pointing to the alt_target with the highest priority.
    """

    pn = d.getVar('BPN')
    pkgdest = d.getVar('PKGD')
    updates = list()
    for alt_name in (d.getVar('ALTERNATIVE:%s' % pkg) or "").split():
        alt_link     = d.getVarFlag('ALTERNATIVE_LINK_NAME', alt_name)
        alt_target   = d.getVarFlag('ALTERNATIVE_TARGET_%s' % pkg, alt_name) or \
                       d.getVarFlag('ALTERNATIVE_TARGET', alt_name) or \
                       d.getVar('ALTERNATIVE_TARGET_%s' % pkg) or \
                       d.getVar('ALTERNATIVE_TARGET') or \
                       alt_link
        alt_priority = d.getVarFlag('ALTERNATIVE_PRIORITY_%s' % pkg,  alt_name) or \
                       d.getVarFlag('ALTERNATIVE_PRIORITY',  alt_name) or \
                       d.getVar('ALTERNATIVE_PRIORITY_%s' % pkg) or  \
                       d.getVar('ALTERNATIVE_PRIORITY')

        # This shouldn't trigger, as it should have been resolved earlier!
        if alt_link == alt_target:
            bb.note('alt_link == alt_target: %s == %s -- correcting, this should not happen!' % (alt_link, alt_target))
            alt_target = '%s.%s' % (alt_target, pn)

        if not os.path.lexists('%s/%s' % (pkgdest, alt_target)):
            bb.warn('%s: NOT adding alternative provide %s: %s does not exist' % (pn, alt_link, alt_target))
            continue

        alt_target = os.path.normpath(alt_target)
        updates.append( (alt_name, alt_link, alt_target, alt_priority) )

    return updates

def update_alternatives_enabled(d):
    # Update Alternatives only works on target packages...
    if bb.data.inherits_class('native', d) or \
       bb.data.inherits_class('cross', d) or bb.data.inherits_class('crosssdk', d) or \
       bb.data.inherits_class('cross-canadian', d):
        return False

    # Disable when targeting mingw32 (no target support)
    if d.getVar("TARGET_OS") == "mingw32":
        return False

    return True