python · miss-islington · Feb 5, 2020 · Feb 5, 2020
diff --git a/Misc/NEWS.d/next/Windows/2020-02-04-19-50-53.bpo-39553._EnweA.rst b/Misc/NEWS.d/next/Windows/2020-02-04-19-50-53.bpo-39553._EnweA.rst
@@ -0,0 +1 @@
+Delete unused code related to SxS manifests.
diff --git a/PC/dl_nt.c b/PC/dl_nt.c
@@ -23,68 +23,6 @@ char dllVersionBuffer[16] = ""; // a private buffer
 HMODULE PyWin_DLLhModule = NULL;
 const char *PyWin_DLLVersionString = dllVersionBuffer;

-#if HAVE_SXS
-// Windows "Activation Context" work.
-// Our .pyd extension modules are generally built without a manifest (ie,
-// those included with Python and those built with a default distutils.
-// This requires we perform some "activation context" magic when loading our
-// extensions.  In summary:
-// * As our DLL loads we save the context being used.
-// * Before loading our extensions we re-activate our saved context.
-// * After extension load is complete we restore the old context.
-// As an added complication, this magic only works on XP or later - we simply
-// use the existence (or not) of the relevant function pointers from kernel32.
-// See bug 4566 (http://python.org/sf/4566) for more details.
-// In Visual Studio 2010, side by side assemblies are no longer used by
-// default.
-
-typedef BOOL (WINAPI * PFN_GETCURRENTACTCTX)(HANDLE *);
-typedef BOOL (WINAPI * PFN_ACTIVATEACTCTX)(HANDLE, ULONG_PTR *);
-typedef BOOL (WINAPI * PFN_DEACTIVATEACTCTX)(DWORD, ULONG_PTR);
-typedef BOOL (WINAPI * PFN_ADDREFACTCTX)(HANDLE);
-typedef BOOL (WINAPI * PFN_RELEASEACTCTX)(HANDLE);
-
-// locals and function pointers for this activation context magic.
-static HANDLE PyWin_DLLhActivationContext = NULL; // one day it might be public
-static PFN_GETCURRENTACTCTX pfnGetCurrentActCtx = NULL;
-static PFN_ACTIVATEACTCTX pfnActivateActCtx = NULL;
-static PFN_DEACTIVATEACTCTX pfnDeactivateActCtx = NULL;
-static PFN_ADDREFACTCTX pfnAddRefActCtx = NULL;
-static PFN_RELEASEACTCTX pfnReleaseActCtx = NULL;
-
-void _LoadActCtxPointers()
-{
-    HINSTANCE hKernel32 = GetModuleHandleW(L"kernel32.dll");
-    if (hKernel32)
-        pfnGetCurrentActCtx = (PFN_GETCURRENTACTCTX) GetProcAddress(hKernel32, "GetCurrentActCtx");
-    // If we can't load GetCurrentActCtx (ie, pre XP) , don't bother with the rest.
-    if (pfnGetCurrentActCtx) {
-        pfnActivateActCtx = (PFN_ACTIVATEACTCTX) GetProcAddress(hKernel32, "ActivateActCtx");
-        pfnDeactivateActCtx = (PFN_DEACTIVATEACTCTX) GetProcAddress(hKernel32, "DeactivateActCtx");
-        pfnAddRefActCtx = (PFN_ADDREFACTCTX) GetProcAddress(hKernel32, "AddRefActCtx");
-        pfnReleaseActCtx = (PFN_RELEASEACTCTX) GetProcAddress(hKernel32, "ReleaseActCtx");
-    }
-}
-
-ULONG_PTR _Py_ActivateActCtx()
-{
-    ULONG_PTR ret = 0;
-    if (PyWin_DLLhActivationContext && pfnActivateActCtx)
-        if (!(*pfnActivateActCtx)(PyWin_DLLhActivationContext, &ret)) {
-            OutputDebugString("Python failed to activate the activation context before loading a DLL\n");
-            ret = 0; // no promise the failing function didn't change it!
-        }
-    return ret;
-}
-
-void _Py_DeactivateActCtx(ULONG_PTR cookie)
-{
-    if (cookie && pfnDeactivateActCtx)
-        if (!(*pfnDeactivateActCtx)(0, cookie))
-            OutputDebugString("Python failed to de-activate the activation context\n");
-}
-#endif /* HAVE_SXS */
-
 BOOL    WINAPI  DllMain (HANDLE hInst,
                                                ULONG ul_reason_for_call,
                                                LPVOID lpReserved)
@@ -98,22 +36,9 @@ BOOL    WINAPI  DllMain (HANDLE hInst,
            // 1000 is a magic number I picked out of the air.  Could do with a #define, I spose...
            LoadString(hInst, 1000, dllVersionBuffer, sizeof(dllVersionBuffer));
 #endif
-
-#if HAVE_SXS
-            // and capture our activation context for use when loading extensions.
-            _LoadActCtxPointers();
-            if (pfnGetCurrentActCtx && pfnAddRefActCtx)
-                if ((*pfnGetCurrentActCtx)(&PyWin_DLLhActivationContext))
-                    if (!(*pfnAddRefActCtx)(PyWin_DLLhActivationContext))
-                        OutputDebugString("Python failed to load the default activation context\n");
-#endif
            break;

        case DLL_PROCESS_DETACH:
-#if HAVE_SXS
-            if (pfnReleaseActCtx)
-                (*pfnReleaseActCtx)(PyWin_DLLhActivationContext);
-#endif
            break;
    }
    return TRUE;

diff --git a/PC/pyconfig.h b/PC/pyconfig.h
@@ -195,11 +195,6 @@ typedef int pid_t;
 #define Py_IS_FINITE(X) _finite(X)
 #define copysign _copysign

-/* Side by Side assemblies supported in VS 2005 and VS 2008 but not 2010*/
-#if _MSC_VER >= 1400 && _MSC_VER < 1600
-#define HAVE_SXS 1
-#endif
-
 /* define some ANSI types that are not defined in earlier Win headers */
 #if _MSC_VER >= 1200
 /* This file only exists in VC 6.0 or higher */

diff --git a/Python/dynload_win.c b/Python/dynload_win.c
@@ -12,12 +12,6 @@
 #include "patchlevel.h"
 #include <windows.h>

-// "activation context" magic - see dl_nt.c...
-#if HAVE_SXS
-extern ULONG_PTR _Py_ActivateActCtx();
-void _Py_DeactivateActCtx(ULONG_PTR cookie);
-#endif
-
 #ifdef _DEBUG
 #define PYD_DEBUG_SUFFIX "_d"
 #else
@@ -187,16 +181,10 @@ dl_funcptr _PyImport_FindSharedFuncptrWindows(const char *prefix,
    {
        HINSTANCE hDLL = NULL;
        unsigned int old_mode;
-#if HAVE_SXS
-        ULONG_PTR cookie = 0;
-#endif

        /* Don't display a message box when Python can't load a DLL */
        old_mode = SetErrorMode(SEM_FAILCRITICALERRORS);

-#if HAVE_SXS
-        cookie = _Py_ActivateActCtx();
-#endif
        /* 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
@@ -206,9 +194,6 @@ dl_funcptr _PyImport_FindSharedFuncptrWindows(const char *prefix,
                              LOAD_LIBRARY_SEARCH_DEFAULT_DIRS |
                              LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR);
        Py_END_ALLOW_THREADS
-#if HAVE_SXS
-        _Py_DeactivateActCtx(cookie);
-#endif

        /* restore old error mode settings */
        SetErrorMode(old_mode);