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1 /* FreezeDLLMain.cpp
2 
3 This is a DLLMain suitable for frozen applications/DLLs on
4 a Windows platform.
5 
6 The general problem is that many Python extension modules may define
7 DLL main functions, but when statically linked together to form
8 a frozen application, this DLLMain symbol exists multiple times.
9 
10 The 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 
24 At this stage, there is a static table of "possibly embedded modules".
25 This should change to something better, but it will work OK for now.
26 
27 Note that this scheme does not handle dependencies in the order
28 of DllMain calls - except it does call pywintypes first :-)
29 
30 As an example of how an extension module with a DllMain should be
31 changed, 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 
49 static char *possibleModules[] = {
50     "pywintypes",
51     "pythoncom",
52     "win32ui",
53     NULL,
54 };
55 
56 BOOL 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 */
PyWinFreeze_ExeInit(void)63 void 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 */
PyWinFreeze_ExeTerm(void)76 void 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 
DllMain(HINSTANCE hInstance,DWORD dwReason,LPVOID lpReserved)88 BOOL 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 
CallModuleDllMain(char * modName,DWORD dwReason)116 BOOL 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