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| -rw-r--r-- | python/vyos/utils/file.py | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/python/vyos/utils/file.py b/python/vyos/utils/file.py new file mode 100644 index 000000000..2560a35be --- /dev/null +++ b/python/vyos/utils/file.py @@ -0,0 +1,171 @@ +# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io> +# +# This library is free software; you can redistribute it and/or +# modify it under the terms of the GNU Lesser General Public +# License as published by the Free Software Foundation; either +# version 2.1 of the License, or (at your option) any later version. +# +# This library is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +# Lesser General Public License for more details. +# +# You should have received a copy of the GNU Lesser General Public +# License along with this library. If not, see <http://www.gnu.org/licenses/>. + +import os + + +def read_file(fname, defaultonfailure=None): + """ + read the content of a file, stripping any end characters (space, newlines) + should defaultonfailure be not None, it is returned on failure to read + """ + try: + """ Read a file to string """ + with open(fname, 'r') as f: + data = f.read().strip() + return data + except Exception as e: + if defaultonfailure is not None: + return defaultonfailure + raise e + +def write_file(fname, data, defaultonfailure=None, user=None, group=None, mode=None, append=False): + """ + Write content of data to given fname, should defaultonfailure be not None, + it is returned on failure to read. + + If directory of file is not present, it is auto-created. + """ + dirname = os.path.dirname(fname) + if not os.path.isdir(dirname): + os.makedirs(dirname, mode=0o755, exist_ok=False) + chown(dirname, user, group) + + try: + """ Write a file to string """ + bytes = 0 + with open(fname, 'w' if not append else 'a') as f: + bytes = f.write(data) + chown(fname, user, group) + chmod(fname, mode) + return bytes + except Exception as e: + if defaultonfailure is not None: + return defaultonfailure + raise e + +def read_json(fname, defaultonfailure=None): + """ + read and json decode the content of a file + should defaultonfailure be not None, it is returned on failure to read + """ + import json + try: + with open(fname, 'r') as f: + data = json.load(f) + return data + except Exception as e: + if defaultonfailure is not None: + return defaultonfailure + raise e + +def chown(path, user, group): + """ change file/directory owner """ + from pwd import getpwnam + from grp import getgrnam + + if user is None or group is None: + return False + + # path may also be an open file descriptor + if not isinstance(path, int) and not os.path.exists(path): + return False + + uid = getpwnam(user).pw_uid + gid = getgrnam(group).gr_gid + os.chown(path, uid, gid) + return True + + +def chmod(path, bitmask): + # path may also be an open file descriptor + if not isinstance(path, int) and not os.path.exists(path): + return + if bitmask is None: + return + os.chmod(path, bitmask) + + +def chmod_600(path): + """ Make file only read/writable by owner """ + from stat import S_IRUSR, S_IWUSR + + bitmask = S_IRUSR | S_IWUSR + chmod(path, bitmask) + + +def chmod_750(path): + """ Make file/directory only executable to user and group """ + from stat import S_IRUSR, S_IWUSR, S_IXUSR, S_IRGRP, S_IXGRP + + bitmask = S_IRUSR | S_IWUSR | S_IXUSR | S_IRGRP | S_IXGRP + chmod(path, bitmask) + + +def chmod_755(path): + """ Make file executable by all """ + from stat import S_IRUSR, S_IWUSR, S_IXUSR, S_IRGRP, S_IXGRP, S_IROTH, S_IXOTH + + bitmask = S_IRUSR | S_IWUSR | S_IXUSR | S_IRGRP | S_IXGRP | \ + S_IROTH | S_IXOTH + chmod(path, bitmask) + + +def makedir(path, user=None, group=None): + if os.path.exists(path): + return + os.makedirs(path, mode=0o755) + chown(path, user, group) + +def wait_for_inotify(file_path, pre_hook=None, event_type=None, timeout=None, sleep_interval=0.1): + """ Waits for an inotify event to occur """ + if not os.path.dirname(file_path): + raise ValueError( + "File path {} does not have a directory part (required for inotify watching)".format(file_path)) + if not os.path.basename(file_path): + raise ValueError( + "File path {} does not have a file part, do not know what to watch for".format(file_path)) + + from inotify.adapters import Inotify + from time import time + from time import sleep + + time_start = time() + + i = Inotify() + i.add_watch(os.path.dirname(file_path)) + + if pre_hook: + pre_hook() + + for event in i.event_gen(yield_nones=True): + if (timeout is not None) and ((time() - time_start) > timeout): + # If the function didn't return until this point, + # the file failed to have been written to and closed within the timeout + raise OSError("Waiting for file {} to be written has failed".format(file_path)) + + # Most such events don't take much time, so it's better to check right away + # and sleep later. + if event is not None: + (_, type_names, path, filename) = event + if filename == os.path.basename(file_path): + if event_type in type_names: + return + sleep(sleep_interval) + +def wait_for_file_write_complete(file_path, pre_hook=None, timeout=None, sleep_interval=0.1): + """ Waits for a process to close a file after opening it in write mode. """ + wait_for_inotify(file_path, + event_type='IN_CLOSE_WRITE', pre_hook=pre_hook, timeout=timeout, sleep_interval=sleep_interval) |