From aca0c9df4ef54f70a3fedb07f4faac463f88a331 Mon Sep 17 00:00:00 2001
From: Karolina Surma <ksurma@redhat.com>
Date: Mon, 10 May 2021 18:16:20 +0200
Subject: [PATCH] Prevent removing of the system packages installed under
 /usr/lib

when pip install -U is executed.

Resolves: rhbz#1550368

Co-Authored-By: Michal Cyprian <m.cyprian@gmail.com>
Co-Authored-By: Victor Stinner <vstinner@redhat.com>
Co-Authored-By: Petr Viktorin <pviktori@redhat.com>
Co-Authored-By: Lumir Balhar <lbalhar@redhat.com>
Co-Authored-By: Miro Hrončok <miro@hroncok.cz>
---
 src/pip/_internal/req/req_install.py               |  3 ++-
 src/pip/_internal/resolution/legacy/resolver.py    |  5 ++++-
 src/pip/_internal/resolution/resolvelib/factory.py | 10 ++++++++++
 src/pip/_internal/utils/misc.py                    | 11 +++++++++++
 4 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/src/pip/_internal/req/req_install.py b/src/pip/_internal/req/req_install.py
index 4c58cdb..3570e17 100644
--- a/src/pip/_internal/req/req_install.py
+++ b/src/pip/_internal/req/req_install.py
@@ -43,6 +43,7 @@ from pip._internal.utils.misc import (
     ask_path_exists,
     backup_dir,
     display_path,
+    dist_in_install_path,
     dist_in_site_packages,
     dist_in_usersite,
     get_distribution,
@@ -426,7 +427,7 @@ class InstallRequirement:
                         "lack sys.path precedence to {} in {}".format(
                             existing_dist.project_name, existing_dist.location)
                     )
-            else:
+            elif dist_in_install_path(existing_dist):
                 self.should_reinstall = True
         else:
             if self.editable:
diff --git a/src/pip/_internal/resolution/legacy/resolver.py b/src/pip/_internal/resolution/legacy/resolver.py
index 4df8f7e..dda2292 100644
--- a/src/pip/_internal/resolution/legacy/resolver.py
+++ b/src/pip/_internal/resolution/legacy/resolver.py
@@ -42,6 +42,7 @@ from pip._internal.resolution.base import BaseResolver, InstallRequirementProvid
 from pip._internal.utils.compatibility_tags import get_supported
 from pip._internal.utils.logging import indent_log
 from pip._internal.utils.misc import dist_in_usersite, normalize_version_info
+from pip._internal.utils.misc import dist_in_install_path
 from pip._internal.utils.packaging import check_requires_python, get_requires_python
 
 logger = logging.getLogger(__name__)
@@ -194,7 +195,9 @@ class Resolver(BaseResolver):
         """
         # Don't uninstall the conflict if doing a user install and the
         # conflict is not a user install.
-        if not self.use_user_site or dist_in_usersite(req.satisfied_by):
+        if ((not self.use_user_site
+                or dist_in_usersite(req.satisfied_by))
+                and dist_in_install_path(req.satisfied_by)):
             req.should_reinstall = True
         req.satisfied_by = None
 
diff --git a/src/pip/_internal/resolution/resolvelib/factory.py b/src/pip/_internal/resolution/resolvelib/factory.py
index e7fd344..555e657 100644
--- a/src/pip/_internal/resolution/resolvelib/factory.py
+++ b/src/pip/_internal/resolution/resolvelib/factory.py
@@ -1,6 +1,7 @@
 import contextlib
 import functools
 import logging
+import sys
 from typing import (
     TYPE_CHECKING,
     Dict,
@@ -34,6 +35,7 @@ from pip._internal.exceptions import (
     UnsupportedWheel,
 )
 from pip._internal.index.package_finder import PackageFinder
+from pip._internal.locations import get_scheme
 from pip._internal.metadata import BaseDistribution, get_default_environment
 from pip._internal.models.link import Link
 from pip._internal.models.wheel import Wheel
@@ -46,6 +48,7 @@ from pip._internal.req.req_install import (
 from pip._internal.resolution.base import InstallRequirementProvider
 from pip._internal.utils.compatibility_tags import get_supported
 from pip._internal.utils.hashes import Hashes
+from pip._internal.utils.misc import dist_location
 from pip._internal.utils.virtualenv import running_under_virtualenv
 
 from .base import Candidate, CandidateVersion, Constraint, Requirement
@@ -525,6 +528,13 @@ class Factory:
         if dist is None:  # Not installed, no uninstallation required.
             return None
 
+        # Prevent uninstalling packages from /usr
+        if dist_location(dist._dist) in (
+                get_scheme('', prefix=sys.base_prefix).purelib,
+                get_scheme('', prefix=sys.base_prefix).platlib,
+            ):
+            return None
+
         # We're installing into global site. The current installation must
         # be uninstalled, no matter it's in global or user site, because the
         # user site installation has precedence over global.
diff --git a/src/pip/_internal/utils/misc.py b/src/pip/_internal/utils/misc.py
index 99ebea3..5901687 100644
--- a/src/pip/_internal/utils/misc.py
+++ b/src/pip/_internal/utils/misc.py
@@ -40,6 +40,7 @@ from pip._vendor.tenacity import retry, stop_after_delay, wait_fixed
 from pip import __version__
 from pip._internal.exceptions import CommandError
 from pip._internal.locations import get_major_minor_version, site_packages, user_site
+from pip._internal.locations import get_scheme
 from pip._internal.utils.compat import WINDOWS, stdlib_pkgs
 from pip._internal.utils.virtualenv import (
     running_under_virtualenv,
@@ -382,6 +383,16 @@ def dist_in_site_packages(dist):
     return dist_location(dist).startswith(normalize_path(site_packages))
 
 
+def dist_in_install_path(dist):
+    """
+    Return True if given Distribution is installed in
+    path matching distutils_scheme layout.
+    """
+    norm_path = normalize_path(dist_location(dist))
+    return norm_path.startswith(normalize_path(
+        get_scheme("").purelib.split('python')[0]))
+
+
 def dist_is_editable(dist):
     # type: (Distribution) -> bool
     """
-- 
2.32.0