From 662ae51a961b06ec240edad988b5c776d04c65c8 Mon Sep 17 00:00:00 2001
From: Naveen M K <naveen521kk@gmail.com>
Date: Sat, 5 Aug 2023 14:10:27 +0530
Subject: [PATCH 099/N] Search DLLs only on paths added using
 `add_dll_directory()`.

This is the default behavior on upstream Python. We previously
reverted this behavior because it broke some use cases.

The old behavior can be restored by setting the environment variable
PYTHONLEGACYWINDOWSDLLLOADING to 1.

Fixes https://github.com/msys2-contrib/cpython-mingw/issues/48
Also fixes https://github.com/msys2-contrib/cpython-mingw/issues/141

Signed-off-by: Naveen M K <naveen521kk@gmail.com>
---
 .github/workflows/mingw.yml            | 10 +++++-----
 Lib/test/__main__.py                   |  8 ++++++++
 Python/dynload_win.c                   | 16 ++++++++++++++--
 Tools/build/check_extension_modules.py |  4 ++++
 mingw_smoketests.py                    |  3 +++
 5 files changed, 34 insertions(+), 7 deletions(-)

diff --git a/.github/workflows/mingw.yml b/.github/workflows/mingw.yml
index 2b606fb..0c9f644 100644
--- a/.github/workflows/mingw.yml
+++ b/.github/workflows/mingw.yml
@@ -124,15 +124,15 @@ jobs:
           cp "${pkgdir}${MINGW_PREFIX}"/bin/idle3 "${pkgdir}${MINGW_PREFIX}"/bin/idle
           cp "${pkgdir}${MINGW_PREFIX}"/bin/pydoc3 "${pkgdir}${MINGW_PREFIX}"/bin/pydoc
 
+          # copy to /
+          cp -rf "${pkgdir}"/* /
+
       - name: Run Smoke Test (installed)
         shell: msys2 {0}
         run: |
-          export PYTHONTZPATH="${MINGW_PREFIX}/share/zoneinfo"
           SMOKETESTS="$(pwd)/mingw_smoketests.py"
-          cd _build
-          cd python_pkgdir/${MINGW_PREFIX}/bin
-          ./python.exe "$SMOKETESTS"
-          MSYSTEM= ./python.exe "$SMOKETESTS"
+          ${MINGW_PREFIX}/bin/python.exe "$SMOKETESTS"
+          MSYSTEM= ${MINGW_PREFIX}/bin/python.exe "$SMOKETESTS"
 
       - name: Compress
         if: always()
diff --git a/Lib/test/__main__.py b/Lib/test/__main__.py
index 82b50ad..25bac39 100644
--- a/Lib/test/__main__.py
+++ b/Lib/test/__main__.py
@@ -1,2 +1,10 @@
+import os
+import sys
+
 from test.libregrtest.main import main
+
+if sys.platform == "win32":
+    # Enable DLL loading from PATH.
+    os.environ["PYTHONLEGACYWINDOWSDLLLOADING"] = "1"
+
 main(_add_python_opts=True)
diff --git a/Python/dynload_win.c b/Python/dynload_win.c
index 1f90e21..db79687 100644
--- a/Python/dynload_win.c
+++ b/Python/dynload_win.c
@@ -4,6 +4,7 @@
 #include "Python.h"
 #include "pycore_fileutils.h"     // _Py_add_relfile()
 #include "pycore_pystate.h"       // _PyInterpreterState_GET()
+#include "pycore_initconfig.h"
 
 #ifdef HAVE_DIRECT_H
 #include <direct.h>
@@ -225,6 +226,18 @@ dl_funcptr _PyImport_FindSharedFuncptrWindows(const char *prefix,
     dl_funcptr p;
     char funcname[258], *import_python;
 
+    int use_legacy = 0;
+    DWORD load_library_flags = 0;
+
+    _Py_get_env_flag(1, &use_legacy, "PYTHONLEGACYWINDOWSDLLLOADING");
+
+    if (use_legacy) {
+        load_library_flags = LOAD_WITH_ALTERED_SEARCH_PATH;
+    } else {
+        load_library_flags = LOAD_LIBRARY_SEARCH_DEFAULT_DIRS |
+                              LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR;
+    }
+
 #ifdef _MSC_VER
     _Py_CheckPython3(); 
 #endif /* _MSC_VER */
@@ -249,8 +262,7 @@ dl_funcptr _PyImport_FindSharedFuncptrWindows(const char *prefix,
            AddDllDirectory function. We add SEARCH_DLL_LOAD_DIR to
            ensure DLLs adjacent to the PYD are preferred. */
         Py_BEGIN_ALLOW_THREADS
-        hDLL = LoadLibraryExW(wpathname, NULL,
-                              LOAD_WITH_ALTERED_SEARCH_PATH);
+        hDLL = LoadLibraryExW(wpathname, NULL, load_library_flags);
         Py_END_ALLOW_THREADS
         PyMem_Free(wpathname);
 
diff --git a/Tools/build/check_extension_modules.py b/Tools/build/check_extension_modules.py
index aa1ade7..7ded0f4 100644
--- a/Tools/build/check_extension_modules.py
+++ b/Tools/build/check_extension_modules.py
@@ -61,6 +61,10 @@ WINDOWS_MODULES = {
     "winsound",
 }
 
+if sys.platform == "win32":
+    # Enable DLL loading from PATH.
+    os.environ["PYTHONLEGACYWINDOWSDLLLOADING"] = "1"
+
 
 logger = logging.getLogger(__name__)
 
diff --git a/mingw_smoketests.py b/mingw_smoketests.py
index 516005c..ca1f652 100644
--- a/mingw_smoketests.py
+++ b/mingw_smoketests.py
@@ -34,6 +34,9 @@ if os.environ.get("MSYSTEM", ""):
 else:
     SEP = "\\"
 
+if sysconfig.is_python_build():
+    os.environ["PYTHONLEGACYWINDOWSDLLLOADING"] = "1"
+
 _UCRT = sysconfig.get_platform() not in ('mingw_x86_64', 'mingw_i686')