Python os.O_TRUNC Examples

def store_config(self, config, global_only):
        """Persists locally or globally configuration object.

        Global configuration is updated only when :global_only: is True,
        otherwise, updates are written to local project configuration
        """
        filepath = self.global_config_path if global_only else \
            self.local_config_path

        if global_only:
            os.umask(0)
            fd = os.open(filepath, os.O_CREAT | os.O_RDWR | os.O_TRUNC, 0o600)
            with self.global_config_lock:
                with open(fd, 'w+') as file:
                    config.write(file)
        else:
            with open(filepath, 'w+') as file:
                config.write(file)

        return self.load_config(local_only=True, global_only=True) 

def upload_config(self):
        try:
            stream = flask.request.stream
            file_path = cfg.find_config_files(project=CONF.project,
                                              prog=CONF.prog)[0]
            flags = os.O_WRONLY | os.O_CREAT | os.O_TRUNC
            # mode 00600
            mode = stat.S_IRUSR | stat.S_IWUSR
            with os.fdopen(os.open(file_path, flags, mode), 'wb') as cfg_file:
                b = stream.read(BUFFER)
                while b:
                    cfg_file.write(b)
                    b = stream.read(BUFFER)

            CONF.mutate_config_files()
        except Exception as e:
            LOG.error("Unable to update amphora-agent configuration: "
                      "{}".format(str(e)))
            return webob.Response(json=dict(
                message="Unable to update amphora-agent configuration.",
                details=str(e)), status=500)

        return webob.Response(json={'message': 'OK'}, status=202) 

def test_write(self):
        test_filename = "tmp.write.test"
        
        # trivial write
        fd = os.open(test_filename, flags)
        self.assertEqual(os.write(fd, "42"), 2)
        os.close(fd)
        os.unlink(test_filename)

        # write to closed file
        fd = os.open(test_filename, flags)
        os.close(fd)
        self.assertRaisesMessage(OSError, "[Errno 9] Bad file descriptor", os.write, fd, "42")
        os.unlink(test_filename)
        
        # write to file with wrong permissions
        fd = os.open(test_filename, os.O_CREAT | os.O_TRUNC | os.O_RDONLY)
        self.assertRaisesMessage(OSError, "[Errno -2146232800] Can not write to " + test_filename,  os.write, fd, "42")
        os.close(fd)
        os.unlink(test_filename) 

def install_netns_systemd_service():
    os_utils = osutils.BaseOS.get_os_util()

    flags = os.O_WRONLY | os.O_CREAT | os.O_TRUNC
    # mode 00644
    mode = (stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP | stat.S_IROTH)

    # TODO(bcafarel): implement this for other init systems
    # netns handling depends on a separate unit file
    netns_path = os.path.join(consts.SYSTEMD_DIR,
                              consts.AMP_NETNS_SVC_PREFIX + '.service')

    jinja_env = jinja2.Environment(
        autoescape=True, loader=jinja2.FileSystemLoader(os.path.dirname(
            os.path.realpath(__file__)
        ) + consts.AGENT_API_TEMPLATES))

    if not os.path.exists(netns_path):
        with os.fdopen(os.open(netns_path, flags, mode), 'w') as text_file:
            text = jinja_env.get_template(
                consts.AMP_NETNS_SVC_PREFIX + '.systemd.j2').render(
                    amphora_nsname=consts.AMPHORA_NAMESPACE,
                    HasIFUPAll=os_utils.has_ifup_all())
            text_file.write(text) 

def __setitem__(self, key, message):
        """Replace the keyed message; raise KeyError if it doesn't exist."""
        path = os.path.join(self._path, str(key))
        try:
            f = open(path, 'rb+')
        except OSError as e:
            if e.errno == errno.ENOENT:
                raise KeyError('No message with key: %s' % key)
            else:
                raise
        try:
            if self._locked:
                _lock_file(f)
            try:
                os.close(os.open(path, os.O_WRONLY | os.O_TRUNC))
                self._dump_message(message, f)
                if isinstance(message, MHMessage):
                    self._dump_sequences(message, key)
            finally:
                if self._locked:
                    _unlock_file(f)
        finally:
            _sync_close(f) 

def is_write_flags(self, open_flags):
        for flag in [os.O_WRONLY, os.O_RDWR, os.O_TRUNC, os.O_CREAT, os.O_EXCL, os.O_TMPFILE]:
            # Strict equality is necessary here, since e.g. O_TMPFILE has multiple bits set,
            # and O_DIRECTORY & O_TMPFILE > 0.
            if open_flags & flag == flag:
                return True

        return False 

def write_port_interface_file(self, netns_interface, fixed_ips, mtu,
                                  interface_file_path, template_port):
        # write interface file

        # If we are using a consolidated interfaces file, just append
        # otherwise clear the per interface file as we are rewriting it
        # TODO(johnsom): We need a way to clean out old interfaces records
        if CONF.amphora_agent.agent_server_network_file:
            flags = os.O_WRONLY | os.O_CREAT | os.O_APPEND
        else:
            flags = os.O_WRONLY | os.O_CREAT | os.O_TRUNC

        # mode 00644
        mode = stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP | stat.S_IROTH

        with os.fdopen(os.open(interface_file_path, flags, mode),
                       'w') as text_file:
            text = self._generate_network_file_text(
                netns_interface, fixed_ips, mtu, template_port)
            text_file.write(text) 

def store_acs_service_principal(subscription_id, client_secret, service_principal,
                                file_name='acsServicePrincipal.json'):
    obj = {}
    if client_secret:
        obj['client_secret'] = client_secret
    if service_principal:
        obj['service_principal'] = service_principal

    config_path = os.path.join(get_config_dir(), file_name)
    full_config = load_service_principals(config_path=config_path)
    if not full_config:
        full_config = {}
    full_config[subscription_id] = obj

    with os.fdopen(os.open(config_path, os.O_RDWR | os.O_CREAT | os.O_TRUNC, 0o600),
                   'w+') as spFile:
        json.dump(full_config, spFile) 

def __init__(self, name, mode):
        mode = {
            "r": os.O_RDONLY,
            "w": os.O_WRONLY | os.O_CREAT | os.O_TRUNC,
        }[mode]
        if hasattr(os, "O_BINARY"):
            mode |= os.O_BINARY
        self.fd = os.open(name, mode, 0o666) 

def new_handle(self, filename, flags=0, attrs=dict(), is_opendir=False):
        if is_opendir:
            handle = self.storage.opendir(filename)
        else:
            os_flags = 0x00000000
            if flags & SSH2_FXF_READ and flags & SSH2_FXF_WRITE:
                os_flags |= os.O_RDWR
            elif flags & SSH2_FXF_READ:
                os_flags |= os.O_RDONLY
            elif flags & SSH2_FXF_WRITE:
                os_flags |= os.O_WRONLY
            if flags & SSH2_FXF_APPEND:
                os_flags |= os.O_APPEND
            if flags & SSH2_FXF_CREAT:
                os_flags |= os.O_CREAT
            if flags & SSH2_FXF_TRUNC and flags & SSH2_FXF_CREAT:
                os_flags |= os.O_TRUNC
            if flags & SSH2_FXF_EXCL and flags & SSH2_FXF_CREAT:
                os_flags |= os.O_EXCL
            mode = attrs.get(b'perm', 0o666)
            handle = self.storage.open(filename, os_flags, mode)
        if self.handle_cnt == 0xffffffffffffffff:
            raise OverflowError()
        self.handle_cnt += 1
        handle_id = bytes(self.handle_cnt)
        self.handles[handle_id] = handle
        if is_opendir:
            self.dirs[handle_id] = filename
        else:
            self.files[handle_id] = filename
        return handle_id 

def flags_to_mode(flags, mode):
        """Convert:
            os module flags and mode -> Paramiko file open mode.
        Note: mode is ignored ATM.
        """
        paramiko_mode = ''
        if flags & os.O_WRONLY or (flags & os.O_WRONLY and flags & os.O_TRUNC):
            paramiko_mode = 'w'
        elif flags & os.O_RDWR and flags & os.O_APPEND:
            paramiko_mode = 'a+'
        elif flags & os.O_RDWR and flags & os.O_CREAT:
            paramiko_mode = 'w+'
        elif flags & os.O_APPEND:
            paramiko_mode = 'a'
        elif flags & os.O_RDWR and flags & os.O_TRUNC:
            paramiko_mode = 'w+'
        elif flags & os.O_RDWR:
            paramiko_mode = 'r+'
        elif flags & os.O_CREAT:
            paramiko_mode = 'w'
        else:  # OS.O_RDONLY fallback to read
            paramiko_mode = 'r'

        if flags & os.O_CREAT and flags & os.O_EXCL:
            paramiko_mode += 'x'

        return paramiko_mode 

def __init__(self, name, mode):
        mode = {
            "r": os.O_RDONLY,
            "w": os.O_WRONLY | os.O_CREAT | os.O_TRUNC,
        }[mode]
        if hasattr(os, "O_BINARY"):
            mode |= os.O_BINARY
        self.fd = os.open(name, mode, 0o666) 

def __init__(self, name, mode):
        mode = {
            "r": os.O_RDONLY,
            "w": os.O_WRONLY | os.O_CREAT | os.O_TRUNC,
        }[mode]
        if hasattr(os, "O_BINARY"):
            mode |= os.O_BINARY
        self.fd = os.open(name, mode, 0o666) 

def open(self, path, flags):
        write_flags = os.O_WRONLY | os.O_RDWR | os.O_APPEND | os.O_TRUNC | os.O_CREAT

        if write_flags & flags:
            raise FuseOSError(EROFS)

        return 0 

def set_sequences(self, sequences):
        """Set sequences using the given name-to-key-list dictionary."""
        f = open(os.path.join(self._path, '.mh_sequences'), 'r+', encoding='ASCII')
        try:
            os.close(os.open(f.name, os.O_WRONLY | os.O_TRUNC))
            for name, keys in sequences.items():
                if len(keys) == 0:
                    continue
                f.write(name + ':')
                prev = None
                completing = False
                for key in sorted(set(keys)):
                    if key - 1 == prev:
                        if not completing:
                            completing = True
                            f.write('-')
                    elif completing:
                        completing = False
                        f.write('%s %s' % (prev, key))
                    else:
                        f.write(' %s' % key)
                    prev = key
                if completing:
                    f.write(str(prev) + '\n')
                else:
                    f.write('\n')
        finally:
            _sync_close(f) 

def __init__(self, name, mode):
        mode = {
            "r": os.O_RDONLY,
            "w": os.O_WRONLY | os.O_CREAT | os.O_TRUNC,
        }[mode]
        if hasattr(os, "O_BINARY"):
            mode |= os.O_BINARY
        self.fd = os.open(name, mode, 0o666) 

def create_empty_file(filename):
    """Create an empty file. If the file already exists, truncate it."""
    fd = os.open(filename, os.O_WRONLY | os.O_CREAT | os.O_TRUNC)
    os.close(fd) 

def flock_exclusive():
    ''' lock so only one snapshot of current config is running '''
    fd = os.open(cfg['lock_file'], os.O_CREAT | os.O_TRUNC | os.O_WRONLY, 0600)
    try:
        fcntl.lockf(fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
    except IOError:
        return False
    return fd 

def create_empty_file(filename):
    """Create an empty file. If the file already exists, truncate it."""
    fd = os.open(filename, os.O_WRONLY | os.O_CREAT | os.O_TRUNC)
    os.close(fd) 

def __init__(self, name, mode):
        mode = {
            "r": os.O_RDONLY,
            "w": os.O_WRONLY | os.O_CREAT | os.O_TRUNC,
        }[mode]
        if hasattr(os, "O_BINARY"):
            mode |= os.O_BINARY
        self.fd = os.open(name, mode, 0o666) 

def __init__(self, name, mode):
        mode = {
            "r": os.O_RDONLY,
            "w": os.O_WRONLY | os.O_CREAT | os.O_TRUNC,
        }[mode]
        if hasattr(os, "O_BINARY"):
            mode |= os.O_BINARY
        self.fd = os.open(name, mode, 0o666) 

def __init__(self, server, filename, flags, attrs):
        self.server = server
        openFlags = 0
        if flags & FXF_READ == FXF_READ and flags & FXF_WRITE == 0:
            openFlags = os.O_RDONLY
        if flags & FXF_WRITE == FXF_WRITE and flags & FXF_READ == 0:
            openFlags = os.O_WRONLY
        if flags & FXF_WRITE == FXF_WRITE and flags & FXF_READ == FXF_READ:
            openFlags = os.O_RDWR
        if flags & FXF_APPEND == FXF_APPEND:
            openFlags |= os.O_APPEND
        if flags & FXF_CREAT == FXF_CREAT:
            openFlags |= os.O_CREAT
        if flags & FXF_TRUNC == FXF_TRUNC:
            openFlags |= os.O_TRUNC
        if flags & FXF_EXCL == FXF_EXCL:
            openFlags |= os.O_EXCL
        if "permissions" in attrs:
            mode = attrs["permissions"]
            del attrs["permissions"]
        else:
            mode = 0o777
        fd = server.avatar._runAsUser(os.open, filename, openFlags, mode)
        if attrs:
            server.avatar._runAsUser(server._setAttrs, filename, attrs)
        self.fd = fd 

def __init__(self, name, mode):
        mode = {
            "r": os.O_RDONLY,
            "w": os.O_WRONLY | os.O_CREAT | os.O_TRUNC,
        }[mode]
        if hasattr(os, "O_BINARY"):
            mode |= os.O_BINARY
        self.fd = os.open(name, mode, 0o666) 

def __init__(self, name, mode):
        mode = {
            "r": os.O_RDONLY,
            "w": os.O_WRONLY | os.O_CREAT | os.O_TRUNC,
        }[mode]
        if hasattr(os, "O_BINARY"):
            mode |= os.O_BINARY
        self.fd = os.open(name, mode, 0o666) 

def __init__(self, name, mode):
        mode = {
            "r": os.O_RDONLY,
            "w": os.O_WRONLY | os.O_CREAT | os.O_TRUNC,
        }[mode]
        if hasattr(os, "O_BINARY"):
            mode |= os.O_BINARY
        self.fd = os.open(name, mode, 0o666) 

def __init__(self, name, mode):
        mode = {
            "r": os.O_RDONLY,
            "w": os.O_WRONLY | os.O_CREAT | os.O_TRUNC,
        }[mode]
        if hasattr(os, "O_BINARY"):
            mode |= os.O_BINARY
        self.fd = os.open(name, mode, 0o666) 

def _acquire(self):
        """
        Unix based locking using fcntl.flock(LOCK_EX | LOCK_NB)
        """
        flags = os.O_RDWR | os.O_CREAT | os.O_TRUNC
        fd = os.open(self._file, flags, 0644)
        try:
            fcntl.flock(fd, fcntl.LOCK_EX|fcntl.LOCK_NB)
            self._fd = fd
        except (IOError, OSError):
            os.close(fd) 

def set_sequences(self, sequences):
        """Set sequences using the given name-to-key-list dictionary."""
        f = open(os.path.join(self._path, '.mh_sequences'), 'r+')
        try:
            os.close(os.open(f.name, os.O_WRONLY | os.O_TRUNC))
            for name, keys in sequences.iteritems():
                if len(keys) == 0:
                    continue
                f.write('%s:' % name)
                prev = None
                completing = False
                for key in sorted(set(keys)):
                    if key - 1 == prev:
                        if not completing:
                            completing = True
                            f.write('-')
                    elif completing:
                        completing = False
                        f.write('%s %s' % (prev, key))
                    else:
                        f.write(' %s' % key)
                    prev = key
                if completing:
                    f.write(str(prev) + '\n')
                else:
                    f.write('\n')
        finally:
            _sync_close(f) 

def __init__(self, name, mode):
        mode = {
            "r": os.O_RDONLY,
            "w": os.O_WRONLY | os.O_CREAT | os.O_TRUNC,
        }[mode]
        if hasattr(os, "O_BINARY"):
            mode |= os.O_BINARY
        self.fd = os.open(name, mode, 0666) 

def __init__(self, name, mode):
        mode = {
            "r": os.O_RDONLY,
            "w": os.O_WRONLY | os.O_CREAT | os.O_TRUNC,
        }[mode]
        if hasattr(os, "O_BINARY"):
            mode |= os.O_BINARY
        self.fd = os.open(name, mode, 0o666)