New submission from STINNER Victor <vstin...@redhat.com>:
The read_pth_file() of PC/getpathp.c sets Py_IsolatedFlag and Py_NoSiteFlag to
1 in Python 3.6. calculate_path() checked if a file with a "._pth" extension
exists in "dllpath" or "progpath".
I refactored deeply the Python initialization in Python 3.7 and I'm not sure I
introduced a regression or not.
In Python 3.7, _PyCoreConfig_Read() calls config_init_path_config() which
indirectly calls read_pth_file(). pymain_read_conf_impl() detects if
Py_IsolatedFlag and Py_NoSiteFlag have been modified and store the new value in
cmdline->isolated and cmdline->no_site_import.
Later, cmdline_set_global_config() sets Py_IsolatedFlag and Py_NoSiteFlag; and
_PyCoreConfig_SetGlobalConfig() sets Py_IgnoreEnvironmentFlag.
The problem is the relationship between isolated/cmdline.Py_IsolatedFlag,
no_site_import/cmdline.Py_NoSiteFlag and
Py_IgnoreEnvironmentFlag/config.ignore_environment. The isolated mode must set
Py_NoSiteFlag to 1 and Py_IgnoreEnvironmentFlag to 1.
For example, pymain_read_conf_impl() uses:
/* Set Py_IgnoreEnvironmentFlag for Py_GETENV() */
Py_IgnoreEnvironmentFlag = config->ignore_environment || cmdline->isolated;
But it's done before calling _PyCoreConfig_Read().
Moreover, _PyCoreConfig_Read() reads PYTHONxxx environment variables before
calling indirectly read_pth_file(), and so PYTHONxxx env vars are read whereas
they are supposed to be ignored.
Calling read_pth_file() earlier is challenging since it depends on
configuration parameters which are before calling it.
At the end, I'm not sure if it's a real issue. I'm not sure if there is a
regression in Python 3.7.
--
But the code in Python 3.8 changed a lot again: _PyCoreConfig_Read() is now
responsible to read all environment variables.
In Python 3.8, read_pth_file() uses a _PyPathConfig structure to set isolated
and site_import parameters. These parameters are then copied to _PyCoreConfig
in _PyCoreConfig_CalculatePathConfig().
Moreover, _PyCoreConfig_Read() is more explicit with the relationship between
isolated, use_environment and user_site_directory. The function *starts* with:
if (config->isolated > 0) {
config->use_environment = 0;
config->user_site_directory = 0;
}
Problems (inconsistencies) arise if isolated is set from 0 to 1 after this code.
----------
components: Interpreter Core
messages: 336760
nosy: vstinner
priority: normal
severity: normal
status: open
title: Windows: python._pth sets isolated mode late during Python initialization
versions: Python 3.7, Python 3.8
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue36136>
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