xref: /third_party/python/PC/frozen_dllmain.c (revision 7db96d56) 
1/* FreezeDLLMain.cpp
2
3This is a DLLMain suitable for frozen applications/DLLs on
4a Windows platform.
5
6The general problem is that many Python extension modules may define
7DLL main functions, but when statically linked together to form
8a frozen application, this DLLMain symbol exists multiple times.
9
10The solution is:
11* Each module checks for a frozen build, and if so, defines its DLLMain
12  function as "__declspec(dllexport) DllMain%module%"
13  (eg, DllMainpythoncom, or DllMainpywintypes)
14
15* The frozen .EXE/.DLL links against this module, which provides
16  the single DllMain.
17
18* This DllMain attempts to locate and call the DllMain for each
19  of the extension modules.
20
21* This code also has hooks to "simulate" DllMain when used from
22  a frozen .EXE.
23
24At this stage, there is a static table of "possibly embedded modules".
25This should change to something better, but it will work OK for now.
26
27Note that this scheme does not handle dependencies in the order
28of DllMain calls - except it does call pywintypes first :-)
29
30As an example of how an extension module with a DllMain should be
31changed, here is a snippet from the pythoncom extension module.
32
33  // end of example code from pythoncom's DllMain.cpp
34  #ifndef BUILD_FREEZE
35  #define DLLMAIN DllMain
36  #define DLLMAIN_DECL
37  #else
38  #define DLLMAIN DllMainpythoncom
39  #define DLLMAIN_DECL __declspec(dllexport)
40  #endif
41
42  extern "C" DLLMAIN_DECL
43  BOOL WINAPI DLLMAIN(HINSTANCE hInstance, DWORD dwReason, LPVOID lpReserved)
44  // end of example code from pythoncom's DllMain.cpp
45
46***************************************************************************/
47#include "windows.h"
48
49static char *possibleModules[] = {
50    "pywintypes",
51    "pythoncom",
52    "win32ui",
53    NULL,
54};
55
56BOOL CallModuleDllMain(char *modName, DWORD dwReason);
57
58
59/*
60  Called by a frozen .EXE only, so that built-in extension
61  modules are initialized correctly
62*/
63void PyWinFreeze_ExeInit(void)
64{
65    char **modName;
66    for (modName = possibleModules;*modName;*modName++) {
67/*              printf("Initialising '%s'\n", *modName); */
68        CallModuleDllMain(*modName, DLL_PROCESS_ATTACH);
69    }
70}
71
72/*
73  Called by a frozen .EXE only, so that built-in extension
74  modules are cleaned up
75*/
76void PyWinFreeze_ExeTerm(void)
77{
78    // Must go backwards
79    char **modName;
80    for (modName = possibleModules+Py_ARRAY_LENGTH(possibleModules)-2;
81         modName >= possibleModules;
82         *modName--) {
83/*              printf("Terminating '%s'\n", *modName);*/
84        CallModuleDllMain(*modName, DLL_PROCESS_DETACH);
85    }
86}
87
88BOOL WINAPI DllMain(HINSTANCE hInstance, DWORD dwReason, LPVOID lpReserved)
89{
90    BOOL ret = TRUE;
91    switch (dwReason) {
92        case DLL_PROCESS_ATTACH:
93        {
94            char **modName;
95            for (modName = possibleModules;*modName;*modName++) {
96                BOOL ok = CallModuleDllMain(*modName, dwReason);
97                if (!ok)
98                    ret = FALSE;
99            }
100            break;
101        }
102        case DLL_PROCESS_DETACH:
103        {
104            // Must go backwards
105            char **modName;
106            for (modName = possibleModules+Py_ARRAY_LENGTH(possibleModules)-2;
107                 modName >= possibleModules;
108                 *modName--)
109                CallModuleDllMain(*modName, DLL_PROCESS_DETACH);
110            break;
111        }
112    }
113    return ret;
114}
115
116BOOL CallModuleDllMain(char *modName, DWORD dwReason)
117{
118    BOOL (WINAPI * pfndllmain)(HINSTANCE, DWORD, LPVOID);
119
120    char funcName[255];
121    HMODULE hmod = GetModuleHandleW(NULL);
122    strcpy(funcName, "_DllMain");
123    strcat(funcName, modName);
124    strcat(funcName, "@12"); // stdcall convention.
125    pfndllmain = (BOOL (WINAPI *)(HINSTANCE, DWORD, LPVOID))GetProcAddress(hmod, funcName);
126    if (pfndllmain==NULL) {
127        /* No function by that name exported - then that module does
128           not appear in our frozen program - return OK
129        */
130        return TRUE;
131    }
132    return (*pfndllmain)(hmod, dwReason, NULL);
133}
134
135