https://github.com/python/cpython/commit/5172fa4cd9f7063b2d3b774dc4a5c0e9eceda612
commit: 5172fa4cd9f7063b2d3b774dc4a5c0e9eceda612
branch: main
author: thexai <[email protected]>
committer: chris-eibl <[email protected]>
date: 2026-09-11T15:35:34+02:00
summary:
gh-152433: Windows: make ``dynload_win.c`` UWP compatible (#152797)
files:
A Misc/NEWS.d/next/Windows/2026-07-01-17-31-05.gh-issue-152433.dod-DF.rst
M Python/dynload_win.c
diff --git
a/Misc/NEWS.d/next/Windows/2026-07-01-17-31-05.gh-issue-152433.dod-DF.rst
b/Misc/NEWS.d/next/Windows/2026-07-01-17-31-05.gh-issue-152433.dod-DF.rst
new file mode 100644
index 00000000000000..e948f5508396ea
--- /dev/null
+++ b/Misc/NEWS.d/next/Windows/2026-07-01-17-31-05.gh-issue-152433.dod-DF.rst
@@ -0,0 +1 @@
+make ``dynload_win.c`` UWP compatible.
diff --git a/Python/dynload_win.c b/Python/dynload_win.c
index 1c2544e94160ac..423a2d2ef21e90 100644
--- a/Python/dynload_win.c
+++ b/Python/dynload_win.c
@@ -164,12 +164,16 @@ _Py_CheckPython3(void)
static int python3_checked = 0;
static HANDLE hPython3;
#define MAXPATHLEN 512
- wchar_t py3path[MAXPATHLEN+1];
if (python3_checked) {
return hPython3 != NULL;
}
python3_checked = 1;
+#ifndef MS_WINDOWS_DESKTOP
+ // LoadPackagedLibrary doesn't accept absolute paths so load dll name from
current app dir
+ hPython3 = LoadPackagedLibrary(PY3_DLLNAME, 0);
+#else
+ wchar_t py3path[MAXPATHLEN + 1];
/* If there is a python3.dll next to the python3y.dll,
use that DLL */
if (PyWin_DLLhModule && GetModuleFileNameW(PyWin_DLLhModule, py3path,
MAXPATHLEN)) {
@@ -202,6 +206,8 @@ _Py_CheckPython3(void)
hPython3 = LoadLibraryExW(py3path, NULL,
LOAD_LIBRARY_SEARCH_DEFAULT_DIRS);
}
}
+#endif
+
return hPython3 != NULL;
#undef MAXPATHLEN
#endif /* PY3_DLLNAME */
@@ -272,6 +278,20 @@ _Py_CheckPython3t(void)
#endif /* Py_ENABLE_SHARED */
+static wchar_t* _Py_AbsolutePath_To_RelativePath(wchar_t* abs_path)
+{
+ wchar_t* rel_path = NULL;
+ wchar_t process_path[512] = { 0 };
+ if (GetModuleFileNameW(NULL, process_path, 512))
+ {
+ wchar_t* path = wcsrchr(process_path, L'\\');
+ path[1] = L'\0'; // strip process name
+ if (wcsstr(abs_path, process_path))
+ rel_path = &abs_path[wcslen(process_path)];
+ }
+ return rel_path;
+}
+
dl_funcptr _PyImport_FindSharedFuncptrWindows(const char *prefix,
const char *shortname,
PyObject *pathname, FILE *fp)
@@ -299,14 +319,24 @@ dl_funcptr _PyImport_FindSharedFuncptrWindows(const char
*prefix,
old_mode = SetErrorMode(SEM_FAILCRITICALERRORS);
#endif
+ Py_BEGIN_ALLOW_THREADS
+#ifndef MS_WINDOWS_DESKTOP
+ // UWP does not allow absolute paths due security restrictions.
+ // If path is contained inside process path (sub folder), use the
relative path instead.
+ wchar_t* rel_path = _Py_AbsolutePath_To_RelativePath(wpathname);
+ if (rel_path)
+ hDLL = LoadPackagedLibrary(rel_path, 0);
+ else
+ hDLL = LoadPackagedLibrary(wpathname, 0);
+#else
/* bpo-36085: We use LoadLibraryEx with restricted search paths
to avoid DLL preloading attacks and enable use of the
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_LIBRARY_SEARCH_DEFAULT_DIRS |
LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR);
+#endif
Py_END_ALLOW_THREADS
PyMem_Free(wpathname);
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