1 /*
2
3 Entry point for the Windows NT DLL.
4
5 About the only reason for having this, is so initall() can automatically
6 be called, removing that burden (and possible source of frustration if
7 forgotten) from the programmer.
8
9 */
10
11 #include "Python.h"
12 #include "windows.h"
13
14 #ifdef Py_ENABLE_SHARED
15 char dllVersionBuffer[16] = ""; // a private buffer
16
17 // Python Globals
18 HMODULE PyWin_DLLhModule = NULL;
19 const char *PyWin_DLLVersionString = dllVersionBuffer;
20
21 // Windows "Activation Context" work:
22 // Our .pyd extension modules are generally built without a manifest (ie,
23 // those included with Python and those built with a default distutils.
24 // This requires we perform some "activation context" magic when loading our
25 // extensions. In summary:
26 // * As our DLL loads we save the context being used.
27 // * Before loading our extensions we re-activate our saved context.
28 // * After extension load is complete we restore the old context.
29 // As an added complication, this magic only works on XP or later - we simply
30 // use the existence (or not) of the relevant function pointers from kernel32.
31 // See bug 4566 (http://python.org/sf/4566) for more details.
32
33 typedef BOOL (WINAPI * PFN_GETCURRENTACTCTX)(HANDLE *);
34 typedef BOOL (WINAPI * PFN_ACTIVATEACTCTX)(HANDLE, ULONG_PTR *);
35 typedef BOOL (WINAPI * PFN_DEACTIVATEACTCTX)(DWORD, ULONG_PTR);
36 typedef BOOL (WINAPI * PFN_ADDREFACTCTX)(HANDLE);
37 typedef BOOL (WINAPI * PFN_RELEASEACTCTX)(HANDLE);
38
39 // locals and function pointers for this activation context magic.
40 static HANDLE PyWin_DLLhActivationContext = NULL; // one day it might be public
41 static PFN_GETCURRENTACTCTX pfnGetCurrentActCtx = NULL;
42 static PFN_ACTIVATEACTCTX pfnActivateActCtx = NULL;
43 static PFN_DEACTIVATEACTCTX pfnDeactivateActCtx = NULL;
44 static PFN_ADDREFACTCTX pfnAddRefActCtx = NULL;
45 static PFN_RELEASEACTCTX pfnReleaseActCtx = NULL;
46
_LoadActCtxPointers()47 void _LoadActCtxPointers()
48 {
49 HINSTANCE hKernel32 = GetModuleHandleW(L"kernel32.dll");
50 if (hKernel32)
51 pfnGetCurrentActCtx = (PFN_GETCURRENTACTCTX) GetProcAddress(hKernel32, "GetCurrentActCtx");
52 // If we can't load GetCurrentActCtx (ie, pre XP) , don't bother with the rest.
53 if (pfnGetCurrentActCtx) {
54 pfnActivateActCtx = (PFN_ACTIVATEACTCTX) GetProcAddress(hKernel32, "ActivateActCtx");
55 pfnDeactivateActCtx = (PFN_DEACTIVATEACTCTX) GetProcAddress(hKernel32, "DeactivateActCtx");
56 pfnAddRefActCtx = (PFN_ADDREFACTCTX) GetProcAddress(hKernel32, "AddRefActCtx");
57 pfnReleaseActCtx = (PFN_RELEASEACTCTX) GetProcAddress(hKernel32, "ReleaseActCtx");
58 }
59 }
60
_Py_ActivateActCtx()61 ULONG_PTR _Py_ActivateActCtx()
62 {
63 ULONG_PTR ret = 0;
64 if (PyWin_DLLhActivationContext && pfnActivateActCtx)
65 if (!(*pfnActivateActCtx)(PyWin_DLLhActivationContext, &ret)) {
66 OutputDebugString("Python failed to activate the activation context before loading a DLL\n");
67 ret = 0; // no promise the failing function didn't change it!
68 }
69 return ret;
70 }
71
_Py_DeactivateActCtx(ULONG_PTR cookie)72 void _Py_DeactivateActCtx(ULONG_PTR cookie)
73 {
74 if (cookie && pfnDeactivateActCtx)
75 if (!(*pfnDeactivateActCtx)(0, cookie))
76 OutputDebugString("Python failed to de-activate the activation context\n");
77 }
78
DllMain(HANDLE hInst,ULONG ul_reason_for_call,LPVOID lpReserved)79 BOOL WINAPI DllMain (HANDLE hInst,
80 ULONG ul_reason_for_call,
81 LPVOID lpReserved)
82 {
83 switch (ul_reason_for_call)
84 {
85 case DLL_PROCESS_ATTACH:
86 PyWin_DLLhModule = hInst;
87 // 1000 is a magic number I picked out of the air. Could do with a #define, I spose...
88 LoadString(hInst, 1000, dllVersionBuffer, sizeof(dllVersionBuffer));
89
90 // and capture our activation context for use when loading extensions.
91 _LoadActCtxPointers();
92 if (pfnGetCurrentActCtx && pfnAddRefActCtx)
93 if ((*pfnGetCurrentActCtx)(&PyWin_DLLhActivationContext))
94 if (!(*pfnAddRefActCtx)(PyWin_DLLhActivationContext))
95 OutputDebugString("Python failed to load the default activation context\n");
96 break;
97
98 case DLL_PROCESS_DETACH:
99 if (pfnReleaseActCtx)
100 (*pfnReleaseActCtx)(PyWin_DLLhActivationContext);
101 break;
102 }
103 return TRUE;
104 }
105
106 #endif /* Py_ENABLE_SHARED */
107