PC/frozen_dllmain.c

   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