diff options
Diffstat (limited to 'Lib/multiprocessing/util.py')
| -rw-r--r-- | Lib/multiprocessing/util.py | 79 |
1 files changed, 77 insertions, 2 deletions
diff --git a/Lib/multiprocessing/util.py b/Lib/multiprocessing/util.py index b7192042b9c..a1a537dd48d 100644 --- a/Lib/multiprocessing/util.py +++ b/Lib/multiprocessing/util.py @@ -19,7 +19,7 @@ from subprocess import _args_from_interpreter_flags # noqa: F401 from . import process __all__ = [ - 'sub_debug', 'debug', 'info', 'sub_warning', 'get_logger', + 'sub_debug', 'debug', 'info', 'sub_warning', 'warn', 'get_logger', 'log_to_stderr', 'get_temp_dir', 'register_after_fork', 'is_exiting', 'Finalize', 'ForkAwareThreadLock', 'ForkAwareLocal', 'close_all_fds_except', 'SUBDEBUG', 'SUBWARNING', @@ -34,6 +34,7 @@ SUBDEBUG = 5 DEBUG = 10 INFO = 20 SUBWARNING = 25 +WARNING = 30 LOGGER_NAME = 'multiprocessing' DEFAULT_LOGGING_FORMAT = '[%(levelname)s/%(processName)s] %(message)s' @@ -53,6 +54,10 @@ def info(msg, *args): if _logger: _logger.log(INFO, msg, *args, stacklevel=2) +def warn(msg, *args): + if _logger: + _logger.log(WARNING, msg, *args, stacklevel=2) + def sub_warning(msg, *args): if _logger: _logger.log(SUBWARNING, msg, *args, stacklevel=2) @@ -121,6 +126,21 @@ abstract_sockets_supported = _platform_supports_abstract_sockets() # Function returning a temp directory which will be removed on exit # +# Maximum length of a socket file path is usually between 92 and 108 [1], +# but Linux is known to use a size of 108 [2]. BSD-based systems usually +# use a size of 104 or 108 and Windows does not create AF_UNIX sockets. +# +# [1]: https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/sys_un.h.html +# [2]: https://man7.org/linux/man-pages/man7/unix.7.html. + +if sys.platform == 'linux': + _SUN_PATH_MAX = 108 +elif sys.platform.startswith(('openbsd', 'freebsd')): + _SUN_PATH_MAX = 104 +else: + # On Windows platforms, we do not create AF_UNIX sockets. + _SUN_PATH_MAX = None if os.name == 'nt' else 92 + def _remove_temp_dir(rmtree, tempdir): rmtree(tempdir) @@ -130,12 +150,67 @@ def _remove_temp_dir(rmtree, tempdir): if current_process is not None: current_process._config['tempdir'] = None +def _get_base_temp_dir(tempfile): + """Get a temporary directory where socket files will be created. + + To prevent additional imports, pass a pre-imported 'tempfile' module. + """ + if os.name == 'nt': + return None + # Most of the time, the default temporary directory is /tmp. Thus, + # listener sockets files "$TMPDIR/pymp-XXXXXXXX/sock-XXXXXXXX" do + # not have a path length exceeding SUN_PATH_MAX. + # + # If users specify their own temporary directory, we may be unable + # to create those files. Therefore, we fall back to the system-wide + # temporary directory /tmp, assumed to exist on POSIX systems. + # + # See https://github.com/python/cpython/issues/132124. + base_tempdir = tempfile.gettempdir() + # Files created in a temporary directory are suffixed by a string + # generated by tempfile._RandomNameSequence, which, by design, + # is 8 characters long. + # + # Thus, the length of socket filename will be: + # + # len(base_tempdir + '/pymp-XXXXXXXX' + '/sock-XXXXXXXX') + sun_path_len = len(base_tempdir) + 14 + 14 + if sun_path_len <= _SUN_PATH_MAX: + return base_tempdir + # Fallback to the default system-wide temporary directory. + # This ignores user-defined environment variables. + # + # On POSIX systems, /tmp MUST be writable by any application [1]. + # We however emit a warning if this is not the case to prevent + # obscure errors later in the execution. + # + # On some legacy systems, /var/tmp and /usr/tmp can be present + # and will be used instead. + # + # [1]: https://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch03s18.html + dirlist = ['/tmp', '/var/tmp', '/usr/tmp'] + try: + base_system_tempdir = tempfile._get_default_tempdir(dirlist) + except FileNotFoundError: + warn("Process-wide temporary directory %s will not be usable for " + "creating socket files and no usable system-wide temporary " + "directory was found in %s", base_tempdir, dirlist) + # At this point, the system-wide temporary directory is not usable + # but we may assume that the user-defined one is, even if we will + # not be able to write socket files out there. + return base_tempdir + warn("Ignoring user-defined temporary directory: %s", base_tempdir) + # at most max(map(len, dirlist)) + 14 + 14 = 36 characters + assert len(base_system_tempdir) + 14 + 14 <= _SUN_PATH_MAX + return base_system_tempdir + def get_temp_dir(): # get name of a temp directory which will be automatically cleaned up tempdir = process.current_process()._config.get('tempdir') if tempdir is None: import shutil, tempfile - tempdir = tempfile.mkdtemp(prefix='pymp-') + base_tempdir = _get_base_temp_dir(tempfile) + tempdir = tempfile.mkdtemp(prefix='pymp-', dir=base_tempdir) info('created temp directory %s', tempdir) # keep a strong reference to shutil.rmtree(), since the finalizer # can be called late during Python shutdown |