def systemd_sysusers_check(d):
    import glob
    import re

    pattern_comment = r'(-|\"[^:\"]+\")'
    pattern_word    = r'[^\s]+'
    pattern_line   = r'(' + pattern_word + r')\s+(' + pattern_word + r')\s+(' + pattern_word + r')(\s+' \
        + pattern_comment + r')?' + r'(\s+(' + pattern_word + r'))?' + r'(\s+(' + pattern_word + r'))?'

    for conffile in glob.glob(os.path.join(d.getVar('IMAGE_ROOTFS'), 'usr/lib/sysusers.d/*.conf')):
        with open(conffile, 'r') as f:
            for line in f:
                line = line.strip()
                if not len(line) or line[0] == '#': continue
                ret = re.fullmatch(pattern_line, line.strip())
                if not ret: continue
                (stype, sname, sid, _, scomment, _, shomedir, _, sshell) = ret.groups()
                if stype == 'u':
                    if sid:
                        (suid, sgid) = resolve_sysusers_id(d, sid)
                        if sgid.isalpha():
                            sgid = check_group_exists(d, gname=sgid)
                        elif sgid.isdigit():
                            check_group_exists(d, gid=sgid)
                        else:
                            sgid = '-'
                    else:
                        suid = '-'
                        sgid = '-'
                    scomment = scomment.replace('"', '') if scomment else '-'
                    shomedir = shomedir or '-'
                    sshell = sshell or '-'
                    e_user = check_user_exists(d, uname=sname)
                    if not e_user:
                        bb.warn('User %s has never been defined' % sname)
                    elif not compare_users((sname, suid, sgid, scomment, shomedir, sshell), e_user):
                        bb.warn('User %s has been defined as (%s) but sysusers.d expects it as (%s)'
                                % (sname, ', '.join(e_user),
                                ', '.join((sname, suid, sgid, scomment, shomedir, sshell))))
                elif stype == 'g':
                    gid = sid or '-'
                    if '/' in gid:
                        (_, gid) = resolve_sysusers_id(d, sid)
                    e_group = check_group_exists(d, gname=sname)
                    if not e_group:
                        bb.warn('Group %s has never been defined' % sname)
                    elif gid != '-':
                        (_, e_gid) = e_group
                        if gid != e_gid:
                            bb.warn('Group %s has been defined with id (%s) but sysusers.d expects gid (%s)'
                                    % (sname, e_gid, gid))
                elif stype == 'm':
                    check_user_exists(d, sname)
                    check_group_exists(d, sid)

systemd_sysusers_check(d)

def resolve_sysusers_id(d, sid):
    # If the id is a path, the uid/gid matchs to the target's uid/gid in the
    # rootfs.
    if '/' in sid:
        try:
            osstat = os.stat(os.path.join(d.getVar('IMAGE_ROOTFS'), sid))
        except FileNotFoundError:
            bb.error('sysusers.d: file %s is required but it does not exist in the rootfs', sid)
            return ('-', '-')
        return (osstat.st_uid, osstat.st_gid)
    # Else it is a uid:gid or uid:groupname syntax
    if ':' in sid:
        return sid.split(':')
    else:
        return (sid, '-')

# Check a user exists in the rootfs password file and return its properties

def compare_users(user, e_user):
    # user and e_user must not have None values. Unset values must be '-'.
    (name, uid, gid, comment, homedir, ushell) = user
    (e_name, e_uid, e_gid, e_comment, e_homedir, e_ushell) = e_user
    # Ignore 'uid', 'gid' or 'homedir' if they are not set
    # Ignore 'shell' and 'ushell' if one is not set
    return name == e_name \
        and (uid == '-' or uid == e_uid) \
        and (gid == '-' or gid == e_gid) \
        and (homedir == '-' or e_homedir == '-' or homedir == e_homedir) \
        and (ushell == '-' or e_ushell == '-' or ushell == e_ushell)

# Open sysusers.d configuration files and parse each line to check the users and
# groups are already defined in /etc/passwd and /etc/groups with similar
# properties. Refer to the sysusers.d(5) manual for its syntax.

def check_user_exists(d, uname=None, uid=None):
    with open(os.path.join(d.getVar('IMAGE_ROOTFS'), 'etc/passwd'), 'r') as pwfile:
        for line in pwfile:
            (name, _, u_id, gid, comment, homedir, ushell) = line.strip().split(':')
            if uname == name or uid == u_id:
                return (name, u_id, gid, comment or '-', homedir or '/', ushell or '-')
    return None

# Check a group exists in the rootfs group file and return its properties

def check_group_exists(d, gname=None, gid=None):
    with open(os.path.join(d.getVar('IMAGE_ROOTFS'), 'etc/group'), 'r') as gfile:
        for line in gfile:
            (name, _, g_id, _) = line.strip().split(':')
            if name == gname or g_id == gid:
                return (name, g_id)
    return None