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+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  
      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  
     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