Python os.setegid() Examples

The following are code examples for showing how to use os.setegid(). They are extracted from open source Python projects. You can vote up the examples you like or vote down the ones you don't like. You can also save this page to your account.

Example 1
Project: hostapd-mana   Author: adde88   File: pamauth.py    (license) View Source Project 6 votes vote down vote up
def callIntoPAM(service, user, conv):
    """A testing hook.
    """
    pam = PAM.pam()
    pam.start(service)
    pam.set_item(PAM.PAM_USER, user)
    pam.set_item(PAM.PAM_CONV, conv)
    gid = os.getegid()
    uid = os.geteuid()
    os.setegid(0)
    os.seteuid(0)
    try:
        pam.authenticate() # these will raise
        pam.acct_mgmt()
        return 1
    finally:
        os.setegid(gid)
        os.seteuid(uid) 
Example 2
Project: sslstrip-hsts-openwrt   Author: adde88   File: pamauth.py    (license) View Source Project 6 votes vote down vote up
def callIntoPAM(service, user, conv):
    """A testing hook.
    """
    pam = PAM.pam()
    pam.start(service)
    pam.set_item(PAM.PAM_USER, user)
    pam.set_item(PAM.PAM_CONV, conv)
    gid = os.getegid()
    uid = os.geteuid()
    os.setegid(0)
    os.seteuid(0)
    try:
        pam.authenticate() # these will raise
        pam.acct_mgmt()
        return 1
    finally:
        os.setegid(gid)
        os.seteuid(uid) 
Example 3
Project: darkc0de-old-stuff   Author: tuwid   File: daemon.py    (GNU General Public License v3.0) View Source Project 5 votes vote down vote up
def main():
    #change to data directory if needed
    os.chdir("/root/data")
    #redirect outputs to a logfile
    sys.stdout = sys.stderr = Log(open(LOGFILE, 'a+'))
    #ensure the that the daemon runs a normal user
    os.setegid(103)     #set group first "pydaemon"
    os.seteuid(103)     #set user "pydaemon"
    #start the user program here:
    USERPROG() 
Example 4
Project: hostapd-mana   Author: adde88   File: util.py    (license) View Source Project 5 votes vote down vote up
def switchUID(uid, gid, euid=False):
    if euid:
        setuid = os.seteuid
        setgid = os.setegid
    else:
        setuid = os.setuid
        setgid = os.setgid
    if gid is not None:
        setgid(gid)
    if uid is not None:
        initgroups(uid, gid)
        setuid(uid) 
Example 5
Project: hostapd-mana   Author: adde88   File: checkers.py    (license) View Source Project 5 votes vote down vote up
def requestAvatarId(self, credentials):
        if pwd:
            try:
                cryptedPass = pwd.getpwnam(credentials.username)[1]
            except KeyError:
                return defer.fail(UnauthorizedLogin())
            else:
                if cryptedPass not in ['*', 'x'] and \
                    verifyCryptedPassword(cryptedPass, credentials.password):
                    return defer.succeed(credentials.username)
        if shadow:
            gid = os.getegid()
            uid = os.geteuid()
            os.setegid(0)
            os.seteuid(0)
            try:
                shadowPass = shadow.getspnam(credentials.username)[1]
            except KeyError:
                os.setegid(gid)
                os.seteuid(uid)
                return defer.fail(UnauthorizedLogin())
            os.setegid(gid)
            os.seteuid(uid)
            if verifyCryptedPassword(shadowPass, credentials.password):
                return defer.succeed(credentials.username)
            return defer.fail(UnauthorizedLogin())
        
        return defer.fail(UnauthorizedLogin()) 
Example 6
Project: hostapd-mana   Author: adde88   File: checkers.py    (license) View Source Project 5 votes vote down vote up
def checkKey(self, credentials):
        sshDir = os.path.expanduser('~%s/.ssh/' % credentials.username)
        if sshDir.startswith('~'): # didn't expand
            return 0
        uid, gid = os.geteuid(), os.getegid()
        ouid, ogid = pwd.getpwnam(credentials.username)[2:4]
        os.setegid(0)
        os.seteuid(0)
        os.setegid(ogid)
        os.seteuid(ouid)
        for name in ['authorized_keys2', 'authorized_keys']:
            if not os.path.exists(sshDir+name):
                continue
            lines = open(sshDir+name).xreadlines()
            os.setegid(0)
            os.seteuid(0)
            os.setegid(gid)
            os.seteuid(uid)
            for l in lines:
                l2 = l.split()
                if len(l2) < 2:
                    continue
                try:
                    if base64.decodestring(l2[1]) == credentials.blob:
                        return 1
                except binascii.Error:
                    continue
        return 0 
Example 7
Project: hostapd-mana   Author: adde88   File: unix.py    (license) View Source Project 5 votes vote down vote up
def _runAsUser(self, f, *args, **kw):
        euid = os.geteuid()
        egid = os.getegid()
        groups = os.getgroups()
        uid, gid = self.getUserGroupId()
        os.setegid(0)
        os.seteuid(0)
        os.setgroups(self.getOtherGroups())
        os.setegid(gid)
        os.seteuid(uid)
        try:
            f = iter(f)
        except TypeError:
            f = [(f, args, kw)]
        try:
            for i in f:
                func = i[0]
                args = len(i)>1 and i[1] or ()
                kw = len(i)>2 and i[2] or {}
                r = func(*args, **kw)
        finally:
            os.setegid(0)
            os.seteuid(0)
            os.setgroups(groups)
            os.setegid(egid)
            os.seteuid(euid)
        return r 
Example 8
Project: hostapd-mana   Author: adde88   File: unix.py    (license) View Source Project 5 votes vote down vote up
def getPtyOwnership(self):
        ttyGid = os.stat(self.ptyTuple[2])[5]
        uid, gid = self.avatar.getUserGroupId()
        euid, egid = os.geteuid(), os.getegid()
        os.setegid(0)
        os.seteuid(0)
        try:
            os.chown(self.ptyTuple[2], uid, ttyGid)
        finally:
            os.setegid(egid)
            os.seteuid(euid) 
Example 9
Project: skilled-hammer   Author: r00m   File: utils.py    (license) View Source Project 5 votes vote down vote up
def pull(directory):
    """
    Pulls latest changes with the user rights that owns the folder
    """
    try:
        st = os.stat(directory)
        logger.info("Pulling as {0}:{1}...".format(st.st_uid, st.st_gid))

        # order is important: after seteuid() call the effective UID isn't 0 anymore, so seteuid() will not be allowed
        os.setegid(st.st_uid)
        os.seteuid(st.st_gid)

        repo = git.Repo(directory)
        info = repo.remotes.origin.pull()[0]

        if info.flags & info.ERROR:
            logger.error("Pull failed: {0}".format(info.note))
            return False
        elif info.flags & info.REJECTED:
            logger.error("Could not merge after pull: {0}".format(info.note))
            return False
        elif info.flags & info.HEAD_UPTODATE:
            logger.info("Head is already up to date")
    except PermissionError:
        logger.error("Insufficient permissions to set uid/gid")
        return False
    finally:
        logger.info("Restoring root permissions")
        os.setegid(0)
        os.seteuid(0)

    return True 
Example 10
Project: skilled-hammer   Author: r00m   File: utils.py    (license) View Source Project 5 votes vote down vote up
def run(project, command, directory, slack_webhook_url):
    """
    Run the specified command as the user that owns the directory
    """
    try:
        st = os.stat(directory)

        # order is important: after seteuid() call the effective UID isn't 0 anymore, so seteuid() will not be allowed
        os.setegid(st.st_uid)
        os.seteuid(st.st_gid)

        logger.info("Changing working directory to '{0}'".format(directory))
        logger.info("Spawning background command '{0}' as {1}:{2} for '{3}'...".format(command, st.st_uid, st.st_gid, project))

        def background():
            """
            I don't care how long it takes to run the command, but Bitbucket gets angry when it takes longer
            than 10 seconds. My npm build takes around 15 secs, so I'd get 3 Webhooks from Bitbucket, because
            it thinks each Webhook timedout.

            Easy way out is to return response immediately and start a background thread that
            does all of the heavy lifting.
            """
            start_time = time.time()
            output = subprocess.check_output(command, shell=True, cwd=directory, stderr=subprocess.STDOUT)
            completed_in = time.time() - start_time

            logger.info("'{0}' background command finished in {1:.2f} seconds".format(project, completed_in))

            if slack_webhook_url:
                slack_notification(slack_webhook_url, "Deployed `{0}` in {1:.2f} seconds! :rocket:".format(project, completed_in), output)

        Thread(target=background).start()
    except PermissionError:
        logger.error("Insufficient permissions to set uid/gid")
    except subprocess.CalledProcessError as e:
        logger.error("Error: {0}".format(e.output))
    finally:
        logger.info("Restoring root permissions")
        os.setegid(0)
        os.seteuid(0) 
Example 11
Project: zippy   Author: securesystemslab   File: test_os.py    (license) View Source Project 5 votes vote down vote up
def test_setegid(self):
                if os.getuid() != 0:
                    self.assertRaises(os.error, os.setegid, 0)
                self.assertRaises(OverflowError, os.setegid, 1<<32) 
Example 12
Project: respeaker_virtualenv   Author: respeaker   File: test_process.py    (license) View Source Project 5 votes vote down vote up
def setUp(self):
            safe_rmpath(TESTFN)
            TestProcess.setUp(self)
            os.setegid(1000)
            os.seteuid(1000) 
Example 13
Project: respeaker_virtualenv   Author: respeaker   File: test_process.py    (license) View Source Project 5 votes vote down vote up
def tearDown(self):
            os.setegid(self.PROCESS_UID)
            os.seteuid(self.PROCESS_GID)
            TestProcess.tearDown(self) 
Example 14
Project: oil   Author: oilshell   File: test_os.py    (license) View Source Project 5 votes vote down vote up
def test_setegid(self):
        if os.getuid() != 0:
            self.assertRaises(os.error, os.setegid, 0)
        self.assertRaises(OverflowError, os.setegid, 1<<32) 
Example 15
Project: python2-tracer   Author: extremecoders-re   File: test_os.py    (license) View Source Project 5 votes vote down vote up
def test_setegid(self):
        if os.getuid() != 0:
            self.assertRaises(os.error, os.setegid, 0)
        self.assertRaises(OverflowError, os.setegid, 1<<32) 
Example 16
Project: sslstrip-hsts-openwrt   Author: adde88   File: util.py    (license) View Source Project 5 votes vote down vote up
def switchUID(uid, gid, euid=False):
    if euid:
        setuid = os.seteuid
        setgid = os.setegid
    else:
        setuid = os.setuid
        setgid = os.setgid
    if gid is not None:
        setgid(gid)
    if uid is not None:
        initgroups(uid, gid)
        setuid(uid) 
Example 17
Project: sslstrip-hsts-openwrt   Author: adde88   File: checkers.py    (license) View Source Project 5 votes vote down vote up
def requestAvatarId(self, credentials):
        if pwd:
            try:
                cryptedPass = pwd.getpwnam(credentials.username)[1]
            except KeyError:
                return defer.fail(UnauthorizedLogin())
            else:
                if cryptedPass not in ['*', 'x'] and \
                    verifyCryptedPassword(cryptedPass, credentials.password):
                    return defer.succeed(credentials.username)
        if shadow:
            gid = os.getegid()
            uid = os.geteuid()
            os.setegid(0)
            os.seteuid(0)
            try:
                shadowPass = shadow.getspnam(credentials.username)[1]
            except KeyError:
                os.setegid(gid)
                os.seteuid(uid)
                return defer.fail(UnauthorizedLogin())
            os.setegid(gid)
            os.seteuid(uid)
            if verifyCryptedPassword(shadowPass, credentials.password):
                return defer.succeed(credentials.username)
            return defer.fail(UnauthorizedLogin())
        
        return defer.fail(UnauthorizedLogin()) 
Example 18
Project: sslstrip-hsts-openwrt   Author: adde88   File: checkers.py    (license) View Source Project 5 votes vote down vote up
def checkKey(self, credentials):
        sshDir = os.path.expanduser('~%s/.ssh/' % credentials.username)
        if sshDir.startswith('~'): # didn't expand
            return 0
        uid, gid = os.geteuid(), os.getegid()
        ouid, ogid = pwd.getpwnam(credentials.username)[2:4]
        os.setegid(0)
        os.seteuid(0)
        os.setegid(ogid)
        os.seteuid(ouid)
        for name in ['authorized_keys2', 'authorized_keys']:
            if not os.path.exists(sshDir+name):
                continue
            lines = open(sshDir+name).xreadlines()
            os.setegid(0)
            os.seteuid(0)
            os.setegid(gid)
            os.seteuid(uid)
            for l in lines:
                l2 = l.split()
                if len(l2) < 2:
                    continue
                try:
                    if base64.decodestring(l2[1]) == credentials.blob:
                        return 1
                except binascii.Error:
                    continue
        return 0 
Example 19
Project: sslstrip-hsts-openwrt   Author: adde88   File: unix.py    (license) View Source Project 5 votes vote down vote up
def _runAsUser(self, f, *args, **kw):
        euid = os.geteuid()
        egid = os.getegid()
        groups = os.getgroups()
        uid, gid = self.getUserGroupId()
        os.setegid(0)
        os.seteuid(0)
        os.setgroups(self.getOtherGroups())
        os.setegid(gid)
        os.seteuid(uid)
        try:
            f = iter(f)
        except TypeError:
            f = [(f, args, kw)]
        try:
            for i in f:
                func = i[0]
                args = len(i)>1 and i[1] or ()
                kw = len(i)>2 and i[2] or {}
                r = func(*args, **kw)
        finally:
            os.setegid(0)
            os.seteuid(0)
            os.setgroups(groups)
            os.setegid(egid)
            os.seteuid(euid)
        return r 
Example 20
Project: sslstrip-hsts-openwrt   Author: adde88   File: unix.py    (license) View Source Project 5 votes vote down vote up
def getPtyOwnership(self):
        ttyGid = os.stat(self.ptyTuple[2])[5]
        uid, gid = self.avatar.getUserGroupId()
        euid, egid = os.geteuid(), os.getegid()
        os.setegid(0)
        os.seteuid(0)
        try:
            os.chown(self.ptyTuple[2], uid, ttyGid)
        finally:
            os.setegid(egid)
            os.seteuid(euid) 
Example 21
Project: web_ctp   Author: molebot   File: test_os.py    (license) View Source Project 5 votes vote down vote up
def test_setegid(self):
                if os.getuid() != 0 and not HAVE_WHEEL_GROUP:
                    self.assertRaises(os.error, os.setegid, 0)
                self.assertRaises(OverflowError, os.setegid, 1<<32) 
Example 22
Project: pefile.pypy   Author: cloudtracer   File: test_os.py    (license) View Source Project 5 votes vote down vote up
def test_setegid(self):
        if os.getuid() != 0:
            self.assertRaises(os.error, os.setegid, 0)
        self.assertRaises(OverflowError, os.setegid, 1<<32) 
Example 23
Project: ouroboros   Author: pybee   File: test_os.py    (license) View Source Project 5 votes vote down vote up
def test_setegid(self):
        if os.getuid() != 0 and not HAVE_WHEEL_GROUP:
            self.assertRaises(OSError, os.setegid, 0)
        self.assertRaises(OverflowError, os.setegid, 1<<32) 
Example 24
Project: ndk-python   Author: gittor   File: test_os.py    (license) View Source Project 5 votes vote down vote up
def test_setegid(self):
                if os.getuid() != 0:
                    self.assertRaises(os.error, os.setegid, 0)
                self.assertRaises(OverflowError, os.setegid, 1<<32) 
Example 25
Project: sdk-samples   Author: cradlepoint   File: authorizers.py    (license) View Source Project 5 votes vote down vote up
def impersonate_user(self, username, password):
            """Change process effective user/group ids to reflect
            logged in user.
            """
            try:
                pwdstruct = pwd.getpwnam(username)
            except KeyError:
                raise AuthorizerError(self.msg_no_such_user)
            else:
                os.setegid(pwdstruct.pw_gid)
                os.seteuid(pwdstruct.pw_uid) 
Example 26
Project: sdk-samples   Author: cradlepoint   File: authorizers.py    (license) View Source Project 5 votes vote down vote up
def terminate_impersonation(self, username):
            """Revert process effective user/group IDs."""
            os.setegid(PROCESS_GID)
            os.seteuid(PROCESS_UID) 
Example 27
Project: navdoon   Author: farzadghanei   File: collector.py    (license) View Source Project 5 votes vote down vote up
def _change_process_user_group(self):
        # type: () -> None
        if self.user:
            self._log("changing process user to {}".format(self.user))
            os.seteuid(self.user)
        if self.group:
            self._log("changing process group to {}".format(self.group))
            os.setegid(self.group) 
Example 28
Project: zenchmarks   Author: squeaky-pl   File: util.py    (license) View Source Project 5 votes vote down vote up
def runAsEffectiveUser(euid, egid, function, *args, **kwargs):
    """
    Run the given function wrapped with seteuid/setegid calls.

    This will try to minimize the number of seteuid/setegid calls, comparing
    current and wanted permissions

    @param euid: effective UID used to call the function.
    @type euid: C{int}

    @type egid: effective GID used to call the function.
    @param egid: C{int}

    @param function: the function run with the specific permission.
    @type function: any callable

    @param *args: arguments passed to C{function}
    @param **kwargs: keyword arguments passed to C{function}
    """
    uid, gid = os.geteuid(), os.getegid()
    if uid == euid and gid == egid:
        return function(*args, **kwargs)
    else:
        if uid != 0 and (uid != euid or gid != egid):
            os.seteuid(0)
        if gid != egid:
            os.setegid(egid)
        if euid != 0 and (euid != uid or gid != egid):
            os.seteuid(euid)
        try:
            return function(*args, **kwargs)
        finally:
            if euid != 0 and (uid != euid or gid != egid):
                os.seteuid(0)
            if gid != egid:
                os.setegid(gid)
            if uid != 0 and (uid != euid or gid != egid):
                os.seteuid(uid) 
Example 29
Project: zenchmarks   Author: squeaky-pl   File: unix.py    (license) View Source Project 5 votes vote down vote up
def _runAsUser(self, f, *args, **kw):
        euid = os.geteuid()
        egid = os.getegid()
        groups = os.getgroups()
        uid, gid = self.getUserGroupId()
        os.setegid(0)
        os.seteuid(0)
        os.setgroups(self.getOtherGroups())
        os.setegid(gid)
        os.seteuid(uid)
        try:
            f = iter(f)
        except TypeError:
            f = [(f, args, kw)]
        try:
            for i in f:
                func = i[0]
                args = len(i) > 1 and i[1] or ()
                kw = len(i) > 2 and i[2] or {}
                r = func(*args, **kw)
        finally:
            os.setegid(0)
            os.seteuid(0)
            os.setgroups(groups)
            os.setegid(egid)
            os.seteuid(euid)
        return r 
Example 30
Project: zenchmarks   Author: squeaky-pl   File: unix.py    (license) View Source Project 5 votes vote down vote up
def getPtyOwnership(self):
        ttyGid = os.stat(self.ptyTuple[2])[5]
        uid, gid = self.avatar.getUserGroupId()
        euid, egid = os.geteuid(), os.getegid()
        os.setegid(0)
        os.seteuid(0)
        try:
            os.chown(self.ptyTuple[2], uid, ttyGid)
        finally:
            os.setegid(egid)
            os.seteuid(euid) 
Example 31
Project: zenchmarks   Author: squeaky-pl   File: test_process.py    (license) View Source Project 5 votes vote down vote up
def setegid(self, egid):
        """
        Mock C{os.setegid}, store result.
        """
        self.setegidCalls.append(egid) 
Example 32
Project: zenchmarks   Author: squeaky-pl   File: test_process.py    (license) View Source Project 5 votes vote down vote up
def tearDown(self):
            os.setegid(self.PROCESS_UID)
            os.seteuid(self.PROCESS_GID)
            TestProcess.tearDown(self) 
Example 33
Project: smart-realestate   Author: stevensshi   File: tortp.py    (license) View Source Project 5 votes vote down vote up
def tor_new_process():
    """
    Drops privileges to TOR_USER user and start a new Tor process
    """
    debian_tor_uid = getpwnam(TOR_USER).pw_uid
    debian_tor_gid = getpwnam(TOR_USER).pw_gid
    os.setgid(debian_tor_gid)
    os.setuid(debian_tor_uid)
    os.setegid(debian_tor_gid)
    os.seteuid(debian_tor_uid)
    os.environ['HOME'] = "/var/lib/tor"

    tor_process = stem.process.launch_tor_with_config(
      config = {
        'SocksPort': '6666',
        'ControlPort': '6969',
        'DNSPort': '9053',
        'DNSListenAddress': '127.0.0.1',
        'AutomapHostsOnResolve': '1',
        'AutomapHostsSuffixes': '.exit,.onion',
        'VirtualAddrNetwork': '10.192.0.0/10',
        'TransPort': '9040',
        'TransListenAddress': '127.0.0.1',
        'AvoidDiskWrites': '1',
        'WarnUnsafeSocks': '1',
      }) 
Example 34
Project: FancyWord   Author: EastonLee   File: test_process.py    (license) View Source Project 5 votes vote down vote up
def setUp(self):
            safe_rmpath(TESTFN)
            TestProcess.setUp(self)
            os.setegid(1000)
            os.seteuid(1000) 
Example 35
Project: FancyWord   Author: EastonLee   File: test_process.py    (license) View Source Project 5 votes vote down vote up
def tearDown(self):
            os.setegid(self.PROCESS_UID)
            os.seteuid(self.PROCESS_GID)
            TestProcess.tearDown(self) 
Example 36
Project: kbe_server   Author: xiaohaoppy   File: test_os.py    (license) View Source Project 5 votes vote down vote up
def test_setegid(self):
        if os.getuid() != 0 and not HAVE_WHEEL_GROUP:
            self.assertRaises(OSError, os.setegid, 0)
        self.assertRaises(OverflowError, os.setegid, 1<<32) 
Example 37
Project: ZServer   Author: zopefoundation   File: filesys.py    (license) View Source Project 5 votes vote down vote up
def become_persona(self):
            if self.persona is not (None, None):
                uid, gid = self.persona
                # the order of these is important!
                os.setegid(gid)
                os.seteuid(uid) 
Example 38
Project: ZServer   Author: zopefoundation   File: filesys.py    (license) View Source Project 5 votes vote down vote up
def become_nobody(self):
            if self.persona is not (None, None):
                os.seteuid(self.PROCESS_UID)
                os.setegid(self.PROCESS_GID)

        # cwd, cdup, open, listdir 
Example 39
Project: procszoo   Author: procszoo   File: mamaji.py    (license) View Source Project 4 votes vote down vote up
def change_users_and_groups(mamaji_data):
    current_users = mamaji_data['current_users']
    current_groups = mamaji_data['current_groups']
    pending_users = mamaji_data['pending_users']
    pending_groups = mamaji_data['pending_groups']
    groups = mamaji_data['supplementary_groups']

    if groups:
        os.setgroups(groups)

    group_types = [k for k in ['rgid', 'egid', 'sgid']
                      if pending_groups[k] is not None]
    group_types_len = len(group_types)
    if group_types_len == 3:
        setresgid(pending_groups['rgid'], pending_groups['egid'],
                      pending_groups['sgid'])
    elif group_types_len == 2:
        if 'rgid' in group_types and 'egid' in group_types:
            os.setregid(pending_groups['rgid'], pending_groups['egid'])
    elif group_types_len == 1:
        if 'egid' in group_types:
            os.setegid(pending_groups['egid'])

    user_types = [k for k in ['ruid', 'euid', 'suid']
                      if pending_users[k] is not None]
    user_types_len = len(user_types)
    if user_types_len == 3:
        setresuid(pending_users['ruid'], pending_users['euid'],
                      pending_users['suid'])
    elif user_types_len == 2:
        if 'ruid' in user_types and 'euid' in user_types:
            os.setreuid(pending_users['ruid'], pending_users['euid'])
    elif user_types_len == 1:
        if 'euid' in user_types:
            os.seteuid(pending_users['euid'])


    if pending_groups['gid'] is not None:
        os.setgid(pending_groups['gid'])

    if pending_users['uid'] is not None:
        os.setuid(pending_users['uid']) 
Example 40
Project: zenchmarks   Author: squeaky-pl   File: util.py    (license) View Source Project 4 votes vote down vote up
def switchUID(uid, gid, euid=False):
    """
    Attempts to switch the uid/euid and gid/egid for the current process.

    If C{uid} is the same value as L{os.getuid} (or L{os.geteuid}),
    this function will issue a L{UserWarning} and not raise an exception.

    @type uid: C{int} or L{None}
    @param uid: the UID (or EUID) to switch the current process to. This
                parameter will be ignored if the value is L{None}.

    @type gid: C{int} or L{None}
    @param gid: the GID (or EGID) to switch the current process to. This
                parameter will be ignored if the value is L{None}.

    @type euid: C{bool}
    @param euid: if True, set only effective user-id rather than real user-id.
                 (This option has no effect unless the process is running
                 as root, in which case it means not to shed all
                 privileges, retaining the option to regain privileges
                 in cases such as spawning processes. Use with caution.)
    """
    if euid:
        setuid = os.seteuid
        setgid = os.setegid
        getuid = os.geteuid
    else:
        setuid = os.setuid
        setgid = os.setgid
        getuid = os.getuid
    if gid is not None:
        setgid(gid)
    if uid is not None:
        if uid == getuid():
            uidText = (euid and "euid" or "uid")
            actionText = "tried to drop privileges and set%s %s" % (uidText, uid)
            problemText = "%s is already %s" % (uidText, getuid())
            warnings.warn("%s but %s; should we be root? Continuing."
                          % (actionText, problemText))
        else:
            initgroups(uid, gid)
            setuid(uid)