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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 */
     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 */
     76 void PyWinFreeze_ExeTerm(void)
     77 {
     78     // Must go backwards
     79     char **modName;
     80     for (modName = possibleModules+(sizeof(possibleModules) / sizeof(char *))-2;
     81          modName >= possibleModules;
     82          *modName--) {
     83 /*              printf("Terminating '%s'\n", *modName);*/
     84         CallModuleDllMain(*modName, DLL_PROCESS_DETACH);
     85     }
     86 }
     87 
     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+(sizeof(possibleModules) / sizeof(char *))-2;
    107                  modName >= possibleModules;
    108                  *modName--)
    109                 CallModuleDllMain(*modName, DLL_PROCESS_DETACH);
    110             break;
    111         }
    112     }
    113     return ret;
    114 }
    115 
    116 BOOL CallModuleDllMain(char *modName, DWORD dwReason)
    117 {
    118     BOOL (WINAPI * pfndllmain)(HINSTANCE, DWORD, LPVOID);
    119 
    120     char funcName[255];
    121     HMODULE hmod = GetModuleHandle(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